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Lima ÉDA, Cavalcante-Silva LHA, Carvalho DCM, Soares MM, Medeiros ABA, Netto CD, Costa PRR, Rodrigues-Mascarenhas S. Immunomodulatory Effects of Pterocarpanquinone LQB-118 in Murine Peritoneal Macrophages. Immunol Invest 2025; 54:494-505. [PMID: 39780421 DOI: 10.1080/08820139.2025.2449949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2025]
Abstract
BACKGROUND Phagocytosis is an important function of macrophages. However, when it's dysregulated, it could compromise homeostasis. Thus, this study aimed to assess the inhibitory activity of pterocarpanquinone LQB 118 on murine macrophage phagocytosis. METHODS We used peritoneal macrophages isolated from mice to evaluate the impact of LQB 118 (5 μM) on the modulation of phagocytic activity and possible action mechanism related: IL-12 (by ELISA), NO (by Griess reaction),ROS production (by flow cytometry), and intracellular signaling proteins (iNOS, P-Akt, P-mTOR, NF-κB, and P-NF-κB) (by flow cytometry).The macrophages were stimulated with zymosan to assess both phagocytic activity and flow cytometry assays. RESULTS Treatment with LQB 118 resulted in a reduction in the phagocytosis of zymosan particles by macrophages. This effect could potentially be attributed to LQB's inhibition of IL-12 production and mTOR/NF-κB signaling. Furthermore, LQB 118 decreased the levels of ROS and NO without interfering with iNOS and Akt activation. CONCLUSION These findings show the anti-phagocytic activity of LQB 118 on macrophage, highlighting the potential of this compound as a candidate for modulating macrophage-driven inflammation.
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Affiliation(s)
| | - Luiz Henrique Agra Cavalcante-Silva
- Biotechnology Center, Federal University of Paraíba, João Pessoa, Brazil
- Medical Sciences and Nursing Complex, Federal University of Alagoas, Arapiraca, Brazil
| | | | | | | | - Chaquip Daher Netto
- Laboratory of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paulo Roberto Ribeiro Costa
- Laboratory of Bioorganic Chemistry, Natural Products Research Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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2
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Festuccia WT. mTORC1 and 2 Adrenergic Regulation and Function in Brown Adipose Tissue. Physiology (Bethesda) 2025; 40:0. [PMID: 39470603 DOI: 10.1152/physiol.00023.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 10/22/2024] [Accepted: 10/24/2024] [Indexed: 10/30/2024] Open
Abstract
Brown adipose tissue (BAT) thermogenesis results from the uncoupling of mitochondrial inner membrane proton gradient mediated by uncoupling protein 1 (UCP-1), which is activated by lipolysis-derived fatty acids. Norepinephrine (NE) secreted by sympathetic innervation not only activates BAT lipolysis and UCP-1 but, uniquely in brown adipocytes, promotes "futile" metabolic cycles and enhances BAT thermogenic capacity by increasing UCP-1 content, mitochondrial biogenesis, and brown adipocyte hyperplasia. NE exerts these actions by triggering signaling in the canonical G protein-coupled β-adrenergic receptors, cAMP, and protein kinase A (PKA) pathway, which in brown adipocytes is under a complex and intricate cross talk with important growth-promoting signaling pathways such as those of mechanistic target of rapamycin (mTOR) complexes 1 (mTORC1) and 2 (mTORC2). This article reviews evidence suggesting that mTOR complexes are modulated by and participate in the thermogenic, metabolic, and growth-promoting effects elicited by NE in BAT and discusses current gaps and future directions in this field of research.
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Gong GQ, Anandapadamanaban M, Islam MS, Hay IM, Bourguet M, Špokaitė S, Dessus AN, Ohashi Y, Perisic O, Williams RL. Making PI3K superfamily enzymes run faster. Adv Biol Regul 2025; 95:101060. [PMID: 39592347 DOI: 10.1016/j.jbior.2024.101060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2024] [Accepted: 11/16/2024] [Indexed: 11/28/2024]
Abstract
The phosphoinositide 3-kinase (PI3K) superfamily includes lipid kinases (PI3Ks and type III PI4Ks) and a group of PI3K-like Ser/Thr protein kinases (PIKKs: mTOR, ATM, ATR, DNA-PKcs, SMG1 and TRRAP) that have a conserved C-terminal kinase domain. A common feature of the superfamily is that they have very low basal activity that can be greatly increased by a range of regulatory factors. Activators reconfigure the active site, causing a subtle realignment of the N-lobe of the kinase domain relative to the C-lobe. This realignment brings the ATP-binding loop in the N-lobe closer to the catalytic residues in the C-lobe. In addition, a conserved C-lobe feature known as the PIKK regulatory domain (PRD) also can change conformation, and PI3K activators can alter an analogous PRD-like region. Recent structures have shown that diverse activating influences can trigger these conformational changes, and a helical region clamping onto the kinase domain transmits regulatory interactions to bring about the active site realignment for more efficient catalysis. A recent report of a small-molecule activator of PI3Kα for application in nerve regeneration suggests that flexibility of these regulatory elements might be exploited to develop specific activators of all PI3K superfamily members. These activators could have roles in wound healing, anti-stroke therapy and treating neurodegeneration. We review common structural features of the PI3K superfamily that may make them amenable to activation.
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Affiliation(s)
- Grace Q Gong
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK; University College London Cancer Institute, University College London, London, UK
| | | | - Md Saiful Islam
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Iain M Hay
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Maxime Bourguet
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Saulė Špokaitė
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Antoine N Dessus
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Yohei Ohashi
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Olga Perisic
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Roger L Williams
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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4
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Xu W, Chen H, Xiao H. mTORC2: A neglected player in aging regulation. J Cell Physiol 2024; 239:e31363. [PMID: 38982866 DOI: 10.1002/jcp.31363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/21/2024] [Accepted: 06/19/2024] [Indexed: 07/11/2024]
Abstract
Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a pivotal role in various biological processes, through integrating external and internal signals, facilitating gene transcription and protein translation, as well as by regulating mitochondria and autophagy functions. mTOR kinase operates within two distinct protein complexes known as mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which engage separate downstream signaling pathways impacting diverse cellular processes. Although mTORC1 has been extensively studied as a pro-proliferative factor and a pro-aging hub if activated aberrantly, mTORC2 received less attention, particularly regarding its implication in aging regulation. However, recent studies brought increasing evidence or clues for us, which implies the associations of mTORC2 with aging, as the genetic elimination of unique subunits of mTORC2, such as RICTOR, has been shown to alleviate aging progression in comparison to mTORC1 inhibition. In this review, we first summarized the basic characteristics of mTORC2, including its protein architecture and signaling network. We then focused on reviewing the molecular signaling regulation of mTORC2 in cellular senescence and organismal aging, and proposed the multifaceted regulatory characteristics under senescent and nonsenescent contexts. Next, we outlined the research progress of mTOR inhibitors in the field of antiaging and discussed future prospects and challenges. It is our pleasure if this review article could provide meaningful information for our readers and call forth more investigations working on this topic.
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Affiliation(s)
- Weitong Xu
- The Lab of Aging Research, National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Honghan Chen
- The Lab of Aging Research, National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Hengyi Xiao
- The Lab of Aging Research, National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
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5
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Yue L, Li J, Yao M, Song S, Zhang X, Wang Y. Cutting edge of immune response and immunosuppressants in allogeneic and xenogeneic islet transplantation. Front Immunol 2024; 15:1455691. [PMID: 39346923 PMCID: PMC11427288 DOI: 10.3389/fimmu.2024.1455691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Accepted: 08/27/2024] [Indexed: 10/01/2024] Open
Abstract
As an effective treatment for diabetes, islet transplantation has garnered significant attention and research in recent years. However, immune rejection and the toxicity of immunosuppressive drugs remain critical factors influencing the success of islet transplantation. While immunosuppressants are essential in reducing immune rejection reactions and can significantly improve the survival rate of islet transplants, improper use of these drugs can markedly increase mortality rates following transplantation. Additionally, the current availability of islet organ donations fails to meet the demand for organ transplants, making xenotransplantation a crucial method for addressing organ shortages. This review will cover the following three aspects: 1) the immune responses occurring during allogeneic islet transplantation, including three stages: inflammation and IBMIR, allogeneic immune response, and autoimmune recurrence; 2) commonly used immunosuppressants in allogeneic islet transplantation, including calcineurin inhibitors (Cyclosporine A, Tacrolimus), mycophenolate mofetil, glucocorticoids, and Bortezomib; and 3) early and late immune responses in xenogeneic islet transplantation and the immune effects of triple therapy (ECDI-fixed donor spleen cells (ECDI-SP) + anti-CD20 + Sirolimus) on xenotransplantation.
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Affiliation(s)
- Liting Yue
- Center of Critical Care Medicine, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Jisong Li
- Department of Gastrointestinal Surgery, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Mingjun Yao
- Center of Critical Care Medicine, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Siyuan Song
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Xiaoqin Zhang
- Center of Critical Care Medicine, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Yi Wang
- Center of Critical Care Medicine, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Clinical Immunology Translational Medicine Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, Chengdu, China
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6
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Allegrini S, Camici M, Garcia-Gil M, Pesi R, Tozzi MG. Interplay between mTOR and Purine Metabolism Enzymes and Its Relevant Role in Cancer. Int J Mol Sci 2024; 25:6735. [PMID: 38928439 PMCID: PMC11203890 DOI: 10.3390/ijms25126735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/14/2024] [Accepted: 06/16/2024] [Indexed: 06/28/2024] Open
Abstract
Tumor cells reprogram their metabolism to meet the increased demand for nucleotides and other molecules necessary for growth and proliferation. In fact, cancer cells are characterized by an increased "de novo" synthesis of purine nucleotides. Therefore, it is not surprising that specific enzymes of purine metabolism are the targets of drugs as antineoplastic agents, and a better knowledge of the mechanisms underlying their regulation would be of great help in finding new therapeutic approaches. The mammalian target of the rapamycin (mTOR) signaling pathway, which is often activated in cancer cells, promotes anabolic processes and is a major regulator of cell growth and division. Among the numerous effects exerted by mTOR, noteworthy is its empowerment of the "de novo" synthesis of nucleotides, accomplished by supporting the formation of purinosomes, and by increasing the availability of necessary precursors, such as one-carbon formyl group, bicarbonate and 5-phosphoribosyl-1-pyrophosphate. In this review, we highlight the connection between purine and mitochondrial metabolism, and the bidirectional relation between mTOR signaling and purine synthesis pathways.
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Affiliation(s)
- Simone Allegrini
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy; (M.C.); (R.P.); (M.G.T.)
- Centro di Ricerca Interdipartimentale Nutrafood “Nutraceuticals and Food for Health”, Università di Pisa, 56126 Pisa, Italy;
- CISUP, Centro per l’Integrazione Della Strumentazione Dell’Università di Pisa, 56127 Pisa, Italy
| | - Marcella Camici
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy; (M.C.); (R.P.); (M.G.T.)
| | - Mercedes Garcia-Gil
- Centro di Ricerca Interdipartimentale Nutrafood “Nutraceuticals and Food for Health”, Università di Pisa, 56126 Pisa, Italy;
- CISUP, Centro per l’Integrazione Della Strumentazione Dell’Università di Pisa, 56127 Pisa, Italy
- Unità di Fisiologia Generale, Dipartimento di Biologia, Università di Pisa, Via San Zeno 31, 56127 Pisa, Italy
| | - Rossana Pesi
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy; (M.C.); (R.P.); (M.G.T.)
| | - Maria Grazia Tozzi
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy; (M.C.); (R.P.); (M.G.T.)
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7
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Emery B, Wood TL. Regulators of Oligodendrocyte Differentiation. Cold Spring Harb Perspect Biol 2024; 16:a041358. [PMID: 38503504 PMCID: PMC11146316 DOI: 10.1101/cshperspect.a041358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Myelination has evolved as a mechanism to ensure fast and efficient propagation of nerve impulses along axons. Within the central nervous system (CNS), myelination is carried out by highly specialized glial cells, oligodendrocytes. The formation of myelin is a prolonged aspect of CNS development that occurs well into adulthood in humans, continuing throughout life in response to injury or as a component of neuroplasticity. The timing of myelination is tightly tied to the generation of oligodendrocytes through the differentiation of their committed progenitors, oligodendrocyte precursor cells (OPCs), which reside throughout the developing and adult CNS. In this article, we summarize our current understanding of some of the signals and pathways that regulate the differentiation of OPCs, and thus the myelination of CNS axons.
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Affiliation(s)
- Ben Emery
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Teresa L Wood
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103, USA
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8
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Ragupathi A, Kim C, Jacinto E. The mTORC2 signaling network: targets and cross-talks. Biochem J 2024; 481:45-91. [PMID: 38270460 PMCID: PMC10903481 DOI: 10.1042/bcj20220325] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/29/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024]
Abstract
The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.
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Affiliation(s)
- Aparna Ragupathi
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
| | - Christian Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
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9
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Werner AN, Kumar AI, Charest PG. CRISPR-mediated reversion of oncogenic KRAS mutation results in increased proliferation and reveals independent roles of Ras and mTORC2 in the migration of A549 lung cancer cells. Mol Biol Cell 2023; 34:ar128. [PMID: 37729017 PMCID: PMC10848948 DOI: 10.1091/mbc.e23-05-0152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/22/2023] Open
Abstract
Although the RAS oncogene has been extensively studied, new aspects concerning its role and regulation in normal biology and cancer continue to be discovered. Recently, others and we have shown that the mechanistic Target of Rapamycin Complex 2 (mTORC2) is a Ras effector in Dictyostelium and mammalian cells. mTORC2 plays evolutionarily conserved roles in cell survival and migration and has been linked to tumorigenesis. Because RAS is often mutated in lung cancer, we investigated whether a Ras-mTORC2 pathway contributes to enhancing the migration of lung cancer cells expressing oncogenic Ras. We used A549 cells and CRISPR/Cas9 to revert the cells' KRAS G12S mutation to wild-type and establish A549 revertant (REV) cell lines, which we then used to evaluate the Ras-mediated regulation of mTORC2 and cell migration. Interestingly, our results suggest that K-Ras and mTORC2 promote A549 cell migration but as part of different pathways and independently of Ras's mutational status. Moreover, further characterization of the A549REV cells revealed that loss of mutant K-Ras expression for the wild-type protein leads to an increase in cell growth and proliferation, suggesting that the A549 cells have low KRAS-mutant dependency and that recovering expression of wild-type K-Ras protein increases these cells tumorigenic potential.
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Affiliation(s)
- Alyssa N. Werner
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721
| | - Avani I. Kumar
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721
| | - Pascale G. Charest
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721
- University of Arizona Cancer Center, Tucson, AZ 85721
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10
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Perpiñán E, Sanchez-Fueyo A, Safinia N. Immunoregulation: the interplay between metabolism and redox homeostasis. FRONTIERS IN TRANSPLANTATION 2023; 2:1283275. [PMID: 38993920 PMCID: PMC11235320 DOI: 10.3389/frtra.2023.1283275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 11/13/2023] [Indexed: 07/13/2024]
Abstract
Regulatory T cells are fundamental for the induction and maintenance of immune homeostasis, with their dysfunction resulting in uncontrolled immune responses and tissue destruction predisposing to autoimmunity, transplant rejection and several inflammatory and metabolic disorders. Recent discoveries have demonstrated that metabolic processes and mitochondrial function are critical for the appropriate functioning of these cells in health, with their metabolic adaptation, influenced by microenvironmental factors, seen in several pathological processes. Upon activation regulatory T cells rearrange their oxidation-reduction (redox) system, which in turn supports their metabolic reprogramming, adding a layer of complexity to our understanding of cellular metabolism. Here we review the literature surrounding redox homeostasis and metabolism of regulatory T cells to highlight new mechanistic insights of these interlinked pathways in immune regulation.
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Affiliation(s)
| | | | - N. Safinia
- Department of Inflammation Biology, School of Immunology and Microbial Sciences, Institute of Liver Studies, James Black Centre, King’s College London, London, United Kingdom
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11
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Rida R, Kreydiyyeh S. Effect of FTY720P on lipid accumulation in HEPG2 cells. Sci Rep 2023; 13:19716. [PMID: 37953311 PMCID: PMC10641067 DOI: 10.1038/s41598-023-46011-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 10/26/2023] [Indexed: 11/14/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is characterized by an increase in hepatic lipid accumulation due to impaired lipid metabolism. Although a correlation was found between NAFLD and sphingosine-1-phosphate (S1P), the role of the sphingolipid remains controversial. The aim of this study was to investigate any involvement of S1P in steatosis using its analog FTY720P and HepG2 cells. Lipid accumulation was induced by incubating the cells in a mixture of oleic and palmitic acid, and was quantified using Oil Red O. The involvement of signaling mediators was studied using pharmacological inhibitors and western blot analysis. FTY720P increased lipid accumulation, but this increase wasn't maintained in the presence of inhibitors of S1PR3, Gq, SREBP, mTOR, PI3K, and PPARγ indicating their involvement in the process. The results revealed that FTY720P binds to S1PR3 which activates sequentially Gq, PI3K, and mTOR leading to an increase in SREBP expression and PPARγ activation. It was concluded that in presence of a high level of fatty acids, lipid accumulation is increased in hepatocytes by the exogenously added FTY720P.
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Affiliation(s)
- Reem Rida
- Department of Biology, Faculty of Arts & Sciences, American University of Beirut, Beirut, Lebanon
| | - Sawsan Kreydiyyeh
- Department of Biology, Faculty of Arts & Sciences, American University of Beirut, Beirut, Lebanon.
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12
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Tserunyan V, Finley SD. A systems and computational biology perspective on advancing CAR therapy. Semin Cancer Biol 2023; 94:34-49. [PMID: 37263529 PMCID: PMC10529846 DOI: 10.1016/j.semcancer.2023.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 04/24/2023] [Accepted: 05/28/2023] [Indexed: 06/03/2023]
Abstract
In the recent decades, chimeric antigen receptor (CAR) therapy signaled a new revolutionary approach to cancer treatment. This method seeks to engineer immune cells expressing an artificially designed receptor, which would endue those cells with the ability to recognize and eliminate tumor cells. While some CAR therapies received FDA approval and others are subject to clinical trials, many aspects of their workings remain elusive. Techniques of systems and computational biology have been frequently employed to explain the operating principles of CAR therapy and suggest further design improvements. In this review, we sought to provide a comprehensive account of those efforts. Specifically, we discuss various computational models of CAR therapy ranging in scale from organismal to molecular. Then, we describe the molecular and functional properties of costimulatory domains frequently incorporated in CAR structure. Finally, we describe the signaling cascades by which those costimulatory domains elicit cellular response against the target. We hope that this comprehensive summary of computational and experimental studies will further motivate the use of systems approaches in advancing CAR therapy.
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Affiliation(s)
- Vardges Tserunyan
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Stacey D Finley
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA; Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA; Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA.
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13
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Wang LJ, Feng F, Li JC, Chen TT, Liu LP. Role of heparanase in pulmonary hypertension. Front Pharmacol 2023; 14:1202676. [PMID: 37637421 PMCID: PMC10450954 DOI: 10.3389/fphar.2023.1202676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 07/26/2023] [Indexed: 08/29/2023] Open
Abstract
Pulmonary hypertension (PH) is a pathophysiological condition of increased pulmonary circulation vascular resistance due to various reasons, which mainly leads to right heart dysfunction and even death, especially in critically ill patients. Although drug interventions have shown some efficacy in improving the hemodynamics of PH patients, the mortality rate remains high. Hence, the identification of new targets and treatment strategies for PH is imperative. Heparanase (HPA) is an enzyme that specifically cleaves the heparan sulfate (HS) side chains in the extracellular matrix, playing critical roles in inflammation and tumorigenesis. Recent studies have indicated a close association between HPA and PH, suggesting HPA as a potential therapeutic target. This review examines the involvement of HPA in PH pathogenesis, including its effects on endothelial cells, inflammation, and coagulation. Furthermore, HPA may serve as a biomarker for diagnosing PH, and the development of HPA inhibitors holds promise as a targeted therapy for PH treatment.
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Affiliation(s)
- Lin-Jun Wang
- The First Clinical Medical School of Lanzhou University, Lanzhou, Gansu, China
| | - Fei Feng
- The First Clinical Medical School of Lanzhou University, Lanzhou, Gansu, China
| | - Jian-Chun Li
- The First Clinical Medical School of Lanzhou University, Lanzhou, Gansu, China
| | - Ting-Ting Chen
- The First Clinical Medical School of Lanzhou University, Lanzhou, Gansu, China
| | - Li-Ping Liu
- The First Clinical Medical School of Lanzhou University, Lanzhou, Gansu, China
- Departments of Emergency Critical Care Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
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Gargalionis AN, Papavassiliou KA, Papavassiliou AG. Implication of mTOR Signaling in NSCLC: Mechanisms and Therapeutic Perspectives. Cells 2023; 12:2014. [PMID: 37566093 PMCID: PMC10416991 DOI: 10.3390/cells12152014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/28/2023] [Accepted: 08/06/2023] [Indexed: 08/12/2023] Open
Abstract
Mechanistic target of the rapamycin (mTOR) signaling pathway represents a central cellular kinase that controls cell survival and metabolism. Increased mTOR activation, along with upregulation of respective upstream and downstream signaling components, have been established as oncogenic features in cancer cells in various tumor types. Nevertheless, mTOR pathway therapeutic targeting has been proven to be quite challenging in various clinical settings. Non-small cell lung cancer (NSCLC) is a frequent type of solid tumor in both genders, where aberrant regulation of the mTOR pathway contributes to the development of oncogenesis, apoptosis resistance, angiogenesis, cancer progression, and metastasis. In this context, the outcome of mTOR pathway targeting in clinical trials still demonstrates unsatisfactory results. Herewith, we discuss recent findings regarding the mechanisms and therapeutic targeting of mTOR signaling networks in NSCLC, as well as future perspectives for the efficient application of treatments against mTOR and related protein molecules.
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Affiliation(s)
- Antonios N. Gargalionis
- Department of Biopathology, ‘Eginition’ Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece;
| | - Kostas A. Papavassiliou
- First University Department of Respiratory Medicine, ‘Sotiria’ Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece;
| | - Athanasios G. Papavassiliou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
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15
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Shi F, Collins S. Regulation of mTOR Signaling: Emerging Role of Cyclic Nucleotide-Dependent Protein Kinases and Implications for Cardiometabolic Disease. Int J Mol Sci 2023; 24:11497. [PMID: 37511253 PMCID: PMC10380887 DOI: 10.3390/ijms241411497] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/07/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
The mechanistic target of rapamycin (mTOR) kinase is a central regulator of cell growth and metabolism. It is the catalytic subunit of two distinct large protein complexes, mTOR complex 1 (mTORC1) and mTORC2. mTOR activity is subjected to tight regulation in response to external nutrition and growth factor stimulation. As an important mechanism of signaling transduction, the 'second messenger' cyclic nucleotides including cAMP and cGMP and their associated cyclic nucleotide-dependent kinases, including protein kinase A (PKA) and protein kinase G (PKG), play essential roles in mediating the intracellular action of a variety of hormones and neurotransmitters. They have also emerged as important regulators of mTOR signaling in various physiological and disease conditions. However, the mechanism by which cAMP and cGMP regulate mTOR activity is not completely understood. In this review, we will summarize the earlier work establishing the ability of cAMP to dampen mTORC1 activation in response to insulin and growth factors and then discuss our recent findings demonstrating the regulation of mTOR signaling by the PKA- and PKG-dependent signaling pathways. This signaling framework represents a new non-canonical regulation of mTOR activity that is independent of AKT and could be a novel mechanism underpinning the action of a variety of G protein-coupled receptors that are linked to the mTOR signaling network. We will further review the implications of these signaling events in the context of cardiometabolic disease, such as obesity, non-alcoholic fatty liver disease, and cardiac remodeling. The metabolic and cardiac phenotypes of mouse models with targeted deletion of Raptor and Rictor, the two essential components for mTORC1 and mTORC2, will be summarized and discussed.
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Affiliation(s)
- Fubiao Shi
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sheila Collins
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
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16
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Mir SA, Dar A, Alshehri SA, Wahab S, Hamid L, Almoyad MAA, Ali T, Bader GN. Exploring the mTOR Signalling Pathway and Its Inhibitory Scope in Cancer. Pharmaceuticals (Basel) 2023; 16:1004. [PMID: 37513916 PMCID: PMC10384750 DOI: 10.3390/ph16071004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
Mechanistic target of rapamycin (mTOR) is a protein kinase that regulates cellular growth, development, survival, and metabolism through integration of diverse extracellular and intracellular stimuli. Additionally, mTOR is involved in interplay of signalling pathways that regulate apoptosis and autophagy. In cells, mTOR is assembled into two complexes, mTORC1 and mTORC2. While mTORC1 is regulated by energy consumption, protein intake, mechanical stimuli, and growth factors, mTORC2 is regulated by insulin-like growth factor-1 receptor (IGF-1R), and epidermal growth factor receptor (EGFR). mTOR signalling pathways are considered the hallmark in cancer due to their dysregulation in approximately 70% of cancers. Through downstream regulators, ribosomal protein S6 kinase β-1 (S6K1) and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1), mTORC1 influences various anabolic and catabolic processes in the cell. In recent years, several mTOR inhibitors have been developed with the aim of treating different cancers. In this review, we will explore the current developments in the mTOR signalling pathway and its importance for being targeted by various inhibitors in anti-cancer therapeutics.
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Affiliation(s)
- Suhail Ahmad Mir
- Department of Pharmaceutical Sciences, University of Kashmir, Hazratbal, Srinagar 190006, Jammu and Kashmir, India
| | - Ashraf Dar
- Department of Biochemistry, University of Kashmir, Hazratbal, Srinagar 190006, Jammu and Kashmir, India
| | - Saad Ali Alshehri
- Department of Pharmacognosy, College of Pharmacy, King Khalid University, Abha 62529, Saudi Arabia
| | - Shadma Wahab
- Department of Pharmacognosy, College of Pharmacy, King Khalid University, Abha 62529, Saudi Arabia
| | - Laraibah Hamid
- Department of Zoology, University of Kashmir, Hazratbal, Srinagar 190006, Jammu and Kashmir, India
| | - Mohammad Ali Abdullah Almoyad
- Department of Basic Medical Sciences, College of Applied Medical Sciences in Khamis Mushyt, King Khalid University, Abha 61412, Saudi Arabia
| | - Tabasum Ali
- Department of Pharmaceutical Sciences, University of Kashmir, Hazratbal, Srinagar 190006, Jammu and Kashmir, India
| | - Ghulam Nabi Bader
- Department of Pharmaceutical Sciences, University of Kashmir, Hazratbal, Srinagar 190006, Jammu and Kashmir, India
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17
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Unali G, Crivicich G, Pagani I, Abou‐Alezz M, Folchini F, Valeri E, Matafora V, Reisz JA, Giordano AMS, Cuccovillo I, Butta GM, Donnici L, D'Alessandro A, De Francesco R, Manganaro L, Cittaro D, Merelli I, Petrillo C, Bachi A, Vicenzi E, Kajaste‐Rudnitski A. Interferon-inducible phospholipids govern IFITM3-dependent endosomal antiviral immunity. EMBO J 2023; 42:e112234. [PMID: 36970857 PMCID: PMC10183820 DOI: 10.15252/embj.2022112234] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 02/27/2023] [Accepted: 03/06/2023] [Indexed: 03/29/2023] Open
Abstract
The interferon-induced transmembrane proteins (IFITM) are implicated in several biological processes, including antiviral defense, but their modes of action remain debated. Here, taking advantage of pseudotyped viral entry assays and replicating viruses, we uncover the requirement of host co-factors for endosomal antiviral inhibition through high-throughput proteomics and lipidomics in cellular models of IFITM restriction. Unlike plasma membrane (PM)-localized IFITM restriction that targets infectious SARS-CoV2 and other PM-fusing viral envelopes, inhibition of endosomal viral entry depends on lysines within the conserved IFITM intracellular loop. These residues recruit Phosphatidylinositol 3,4,5-trisphosphate (PIP3) that we show here to be required for endosomal IFITM activity. We identify PIP3 as an interferon-inducible phospholipid that acts as a rheostat for endosomal antiviral immunity. PIP3 levels correlated with the potency of endosomal IFITM restriction and exogenous PIP3 enhanced inhibition of endocytic viruses, including the recent SARS-CoV2 Omicron variant. Together, our results identify PIP3 as a critical regulator of endosomal IFITM restriction linking it to the Pi3K/Akt/mTORC pathway and elucidate cell-compartment-specific antiviral mechanisms with potential relevance for the development of broadly acting antiviral strategies.
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Affiliation(s)
- Giulia Unali
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
- Vita‐Salute San Raffaele UniversityMilanItaly
| | - Giovanni Crivicich
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Isabel Pagani
- Viral Pathogenesis and Biosafety UnitIRCCS Ospedale San RaffaeleMilanItaly
| | - Monah Abou‐Alezz
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Filippo Folchini
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Erika Valeri
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
- Vita‐Salute San Raffaele UniversityMilanItaly
| | | | - Julie A Reisz
- Department of Biochemistry and Molecular GeneticsUniversity of Colorado Anschutz Medical CampusAuroraCOUSA
| | - Anna Maria Sole Giordano
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Ivan Cuccovillo
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Giacomo M Butta
- INGM, Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi"MilanItaly
- Department of Pharmacological and Biomolecular Sciences (DiSFeB)University of MilanMilanItaly
| | - Lorena Donnici
- INGM, Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi"MilanItaly
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular GeneticsUniversity of Colorado Anschutz Medical CampusAuroraCOUSA
| | - Raffaele De Francesco
- INGM, Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi"MilanItaly
- Department of Pharmacological and Biomolecular Sciences (DiSFeB)University of MilanMilanItaly
| | - Lara Manganaro
- INGM, Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi"MilanItaly
- Department of Pharmacological and Biomolecular Sciences (DiSFeB)University of MilanMilanItaly
| | - Davide Cittaro
- Center for Omics SciencesIRCCS Ospedale San RaffaeleMilanItaly
| | - Ivan Merelli
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Carolina Petrillo
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Angela Bachi
- FIRC Institute of Molecular Oncology (IFOM)MilanItaly
| | - Elisa Vicenzi
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
| | - Anna Kajaste‐Rudnitski
- San Raffaele Telethon Institute for Gene Therapy (SR‐TIGET), IRCCS Ospedale San RaffaeleMilanItaly
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18
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Chantaravisoot N, Wongkongkathep P, Kalpongnukul N, Pacharakullanon N, Kaewsapsak P, Ariyachet C, Loo JA, Tamanoi F, Pisitkun T. mTORC2 interactome and localization determine aggressiveness of high-grade glioma cells through association with gelsolin. Sci Rep 2023; 13:7037. [PMID: 37120454 PMCID: PMC10148843 DOI: 10.1038/s41598-023-33872-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 04/20/2023] [Indexed: 05/01/2023] Open
Abstract
mTOR complex 2 (mTORC2) has been implicated as a key regulator of glioblastoma cell migration. However, the roles of mTORC2 in the migrational control process have not been entirely elucidated. Here, we elaborate that active mTORC2 is crucial for GBM cell motility. Inhibition of mTORC2 impaired cell movement and negatively affected microfilament and microtubule functions. We also aimed to characterize important players involved in the regulation of cell migration and other mTORC2-mediated cellular processes in GBM cells. Therefore, we quantitatively characterized the alteration of the mTORC2 interactome under selective conditions using affinity purification-mass spectrometry in glioblastoma. We demonstrated that changes in cell migration ability specifically altered mTORC2-associated proteins. GSN was identified as one of the most dynamic proteins. The mTORC2-GSN linkage was mostly highlighted in high-grade glioma cells, connecting functional mTORC2 to multiple proteins responsible for directional cell movement in GBM. Loss of GSN disconnected mTORC2 from numerous cytoskeletal proteins and affected the membrane localization of mTORC2. In addition, we reported 86 stable mTORC2-interacting proteins involved in diverse molecular functions, predominantly cytoskeletal remodeling, in GBM. Our findings might help expand future opportunities for predicting the highly migratory phenotype of brain cancers in clinical investigations.
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Affiliation(s)
- Naphat Chantaravisoot
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand.
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
| | - Piriya Wongkongkathep
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
- Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Nuttiya Kalpongnukul
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Narawit Pacharakullanon
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand
| | - Pornchai Kaewsapsak
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand
- Research Unit of Systems Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Chaiyaboot Ariyachet
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand
- Center of Excellence in Hepatitis and Liver Cancer, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
- UCLA/DOE Institute of Genomics and Proteomics, University of California, Los Angeles, CA, 90095, USA
- Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Fuyuhiko Tamanoi
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
- Institute for Integrated Cell-Material Sciences, Institute for Advanced Study, Kyoto University, Kyoto, 606-8501, Japan
| | - Trairak Pisitkun
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
- Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
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19
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Das F, Ghosh-Choudhury N, Maity S, Kasinath BS, Ghosh Choudhury G. TGFβ instructs mTORC2 to activate PKCβII for increased TWIST1 expression in proximal tubular epithelial cell injury. FEBS Lett 2023; 597:1300-1316. [PMID: 36775967 DOI: 10.1002/1873-3468.14599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/13/2023] [Accepted: 02/02/2023] [Indexed: 02/14/2023]
Abstract
The plasticity of proximal tubular epithelial cells in response to TGFβ contributes to the expression of TWIST1 to drive renal fibrosis. The mechanism of TWIST1 expression is not known. We show that both PI3 kinase and its target mTORC2 increase TGFβ-induced TWIST1 expression. TGFβ enhances phosphorylation on Ser-660 in the protein kinase C βII (PKCβII) hydrophobic motif site. Remarkably, phosphorylation-deficient PKCβIIS660A, kinase-dead PKCβII, and PKCβII knockdown blocked TWIST1 expression by TGFβ. Inhibition of TWIST1 arrested TGFβ-induced tubular cell hypertrophy and the expression of fibronectin, collagen I (α2), and α-smooth muscle actin. By contrast, TWIST1 overexpression induced these pathologies. Interestingly, the inhibition of PKCβII reduced these phenomena, which were countered by the expression of TWIST1. These results provide the first evidence for the involvement of the mTORC2-PKCβII axis in TWIST1 expression to promote tubular cell pathology.
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Affiliation(s)
- Falguni Das
- 1VA Research and 4Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, TX, 78229, USA.,Department of Medicine, UT Health San Antonio, TX, USA
| | | | - Soumya Maity
- Department of Medicine, UT Health San Antonio, TX, USA
| | | | - Goutam Ghosh Choudhury
- 1VA Research and 4Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, TX, 78229, USA.,Department of Medicine, UT Health San Antonio, TX, USA.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA
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20
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Abou Daher A, Alkhansa S, Azar WS, Rafeh R, Ghadieh HE, Eid AA. Translational Aspects of the Mammalian Target of Rapamycin Complexes in Diabetic Nephropathy. Antioxid Redox Signal 2022; 37:802-819. [PMID: 34544257 DOI: 10.1089/ars.2021.0217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Significance: Despite the many efforts put into understanding diabetic nephropathy (DN), direct treatments for DN have yet to be discovered. Understanding the mechanisms behind DN is an essential step in the development of novel therapeutic regimens. The mammalian target of rapamycin (mTOR) pathway has emerged as an important candidate in the quest for drug discovery because of its role in regulating growth, proliferation, as well as protein and lipid metabolism. Recent Advances: Kidney cells have been found to rely on basal autophagy for survival and for conserving kidney integrity. Recent studies have shown that diabetes induces renal autophagy deregulation, leading to kidney injury. Hyper-activation of the mTOR pathway and oxidative stress have been suggested to play a role in diabetes-induced autophagy imbalance. Critical Issues: A detailed understanding of the role of mTOR signaling in diabetes-associated complications is of major importance in the search for a cure. In this review, we provide evidence that mTOR is heavily implicated in diabetes-induced kidney injury. We suggest possible mechanisms through which mTOR exerts its negative effects by increasing insulin resistance, upregulating oxidative stress, and inhibiting autophagy. Future Directions: Both increased oxidative stress and autophagy deregulation are deeply embedded in DN. However, the mechanisms controlling oxidative stress and autophagy are not well understood. Although Akt/mTOR signaling seems to play an important role in oxidative stress and autophagy, further investigation is required to uncover the details of this signaling pathway. Antioxid. Redox Signal. 37, 802-819.
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Affiliation(s)
- Alaa Abou Daher
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Sahar Alkhansa
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - William S Azar
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,Department of Physiology and Biophysics, Georgetown University Medical School, Washington, District of Columbia, USA
| | - Rim Rafeh
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Hilda E Ghadieh
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Assaad A Eid
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
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21
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Wang Z, Ye M, Zhang XJ, Zhang P, Cai J, Li H, She ZG. Impact of NAFLD and its pharmacotherapy on lipid profile and CVD. Atherosclerosis 2022; 355:30-44. [PMID: 35872444 DOI: 10.1016/j.atherosclerosis.2022.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 06/16/2022] [Accepted: 07/13/2022] [Indexed: 11/21/2022]
Abstract
Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death worldwide. Increasing evidence suggests that, in addition to traditional metabolic risk factors such as obesity, hypercholesterolemia, hypertension, diabetes mellitus, and insulin resistance (IR), nonalcoholic fatty liver disease (NAFLD) is an emerging driver of ASCVD via multiple mechanisms, mainly by disrupting lipid metabolism. The lack of pharmaceutical treatment has spurred substantial investment in the research and development of NAFLD drugs. However, many reagents with promising therapeutic potential for NAFLD also have considerable impacts on the circulating lipid profile. In this review, we first summarize the mechanisms linking lipid dysregulation in NAFLD to the progression of ASCVD. Importantly, we highlight the potential risks of/benefits to ASCVD conferred by NAFLD pharmaceutical treatments and discuss potential strategies and next-generation drugs for treating NAFLD without the unwanted side effects.
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Affiliation(s)
- Zhenya Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China; Institute of Model Animal, Wuhan University, Wuhan, China
| | - Mao Ye
- Department of Cardiology, Huanggang Central Hospital, HuBei Province, China; Huanggang Institute of Translational Medicine, Huanggang, China
| | - Xiao-Jing Zhang
- Institute of Model Animal, Wuhan University, Wuhan, China; School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Peng Zhang
- Institute of Model Animal, Wuhan University, Wuhan, China; School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Jingjing Cai
- Institute of Model Animal, Wuhan University, Wuhan, China; Department of Cardiology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Hongliang Li
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China; Institute of Model Animal, Wuhan University, Wuhan, China; Huanggang Institute of Translational Medicine, Huanggang, China.
| | - Zhi-Gang She
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China; Institute of Model Animal, Wuhan University, Wuhan, China.
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22
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Bandyopadhyay G, Tang K, Webster NJG, van den Bogaart G, Mahata SK. Catestatin induces glycogenesis by stimulating the phosphoinositide 3-kinase-AKT pathway. Acta Physiol (Oxf) 2022; 235:e13775. [PMID: 34985191 PMCID: PMC10754386 DOI: 10.1111/apha.13775] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 10/19/2021] [Accepted: 01/01/2022] [Indexed: 12/12/2022]
Abstract
AIM Defects in hepatic glycogen synthesis contribute to post-prandial hyperglycaemia in type 2 diabetic patients. Chromogranin A (CgA) peptide Catestatin (CST: hCgA352-372 ) improves glucose tolerance in insulin-resistant mice. Here, we seek to determine whether CST induces hepatic glycogen synthesis. METHODS We determined liver glycogen, glucose-6-phosphate (G6P), uridine diphosphate glucose (UDPG) and glycogen synthase (GYS2) activities; plasma insulin, glucagon, noradrenaline and adrenaline levels in wild-type (WT) as well as in CST knockout (CST-KO) mice; glycogen synthesis and glycogenolysis in primary hepatocytes. We also analysed phosphorylation signals of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phosphatidylinositol-dependent kinase-1 (PDK-1), GYS2, glycogen synthase kinase-3β (GSK-3β), AKT (a kinase in AKR mouse that produces Thymoma)/PKB (protein kinase B) and mammalian/mechanistic target of rapamycin (mTOR) by immunoblotting. RESULTS CST stimulated glycogen accumulation in fed and fasted liver and in primary hepatocytes. CST reduced plasma noradrenaline and adrenaline levels. CST also directly stimulated glycogenesis and inhibited noradrenaline and adrenaline-induced glycogenolysis in hepatocytes. In addition, CST elevated the levels of UDPG and increased GYS2 activity. CST-KO mice had decreased liver glycogen that was restored by treatment with CST, reinforcing the crucial role of CST in hepatic glycogenesis. CST improved insulin signals downstream of IR and IRS-1 by enhancing phospho-AKT signals through the stimulation of PDK-1 and mTORC2 (mTOR Complex 2, rapamycin-insensitive complex) activities. CONCLUSIONS CST directly promotes the glycogenic pathway by (a) reducing glucose production, (b) increasing glycogen synthesis from UDPG, (c) reducing glycogenolysis and (d) enhancing downstream insulin signalling.
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Affiliation(s)
- Gautam Bandyopadhyay
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Kechun Tang
- VA San Diego Healthcare System, San Diego, California, USA
| | - Nicholas J. G. Webster
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- VA San Diego Healthcare System, San Diego, California, USA
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Sushil K. Mahata
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- VA San Diego Healthcare System, San Diego, California, USA
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23
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Huan J, Grivas P, Birch J, Hansel DE. Emerging Roles for Mammalian Target of Rapamycin (mTOR) Complexes in Bladder Cancer Progression and Therapy. Cancers (Basel) 2022; 14:1555. [PMID: 35326708 PMCID: PMC8946148 DOI: 10.3390/cancers14061555] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/03/2022] [Accepted: 03/15/2022] [Indexed: 12/15/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) pathway regulates important cellular functions. Aberrant activation of this pathway, either through upstream activation by growth factors, loss of inhibitory controls, or molecular alterations, can enhance cancer growth and progression. Bladder cancer shows high levels of mTOR activity in approximately 70% of urothelial carcinomas, suggesting a key role for this pathway in this cancer. mTOR signaling initiates through upstream activation of phosphatidylinositol 3 kinase (PI3K) and protein kinase B (AKT) and results in activation of either mTOR complex 1 (mTORC1) or mTOR complex 2 (mTORC2). While these complexes share several key protein components, unique differences in their complex composition dramatically alter the function and downstream cellular targets of mTOR activity. While significant work has gone into analysis of molecular alterations of the mTOR pathway in bladder cancer, this has not yielded significant benefit in mTOR-targeted therapy approaches in urothelial carcinoma to date. New discoveries regarding signaling convergence onto mTOR complexes in bladder cancer could yield unique insights the biology and targeting of this aggressive disease. In this review, we highlight the functional significance of mTOR signaling in urothelial carcinoma and its potential impact on future therapy implications.
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Affiliation(s)
- Jianya Huan
- Department of Pathology & Laboratory Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (J.H.); (J.B.)
| | - Petros Grivas
- Division of Medical Oncology, Department of Medicine, University of Washington School of Medicine, Fred Hutchinson Cancer Research Center, Seattle Cancer Care Alliance, Seattle, WA 98195, USA;
| | - Jasmine Birch
- Department of Pathology & Laboratory Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (J.H.); (J.B.)
| | - Donna E. Hansel
- Department of Pathology & Laboratory Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (J.H.); (J.B.)
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Gargalionis AN, Papavassiliou KA, Basdra EK, Papavassiliou AG. mTOR Signaling Components in Tumor Mechanobiology. Int J Mol Sci 2022; 23:1825. [PMID: 35163745 PMCID: PMC8837098 DOI: 10.3390/ijms23031825] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 11/17/2022] Open
Abstract
Mechanistic target of rapamycin (mTOR) is a central signaling hub that integrates networks of nutrient availability, cellular metabolism, and autophagy in eukaryotic cells. mTOR kinase, along with its upstream regulators and downstream substrates, is upregulated in most human malignancies. At the same time, mechanical forces from the tumor microenvironment and mechanotransduction promote cancer cells' proliferation, motility, and invasion. mTOR signaling pathway has been recently found on the crossroads of mechanoresponsive-induced signaling cascades to regulate cell growth, invasion, and metastasis in cancer cells. In this review, we examine the emerging association of mTOR signaling components with certain protein tools of tumor mechanobiology. Thereby, we highlight novel mechanisms of mechanotransduction, which regulate tumor progression and invasion, as well as mechanisms related to the therapeutic efficacy of antitumor drugs.
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Affiliation(s)
- Antonios N. Gargalionis
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (K.A.P.); (E.K.B.)
- Department of Biopathology, Aeginition Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Kostas A. Papavassiliou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (K.A.P.); (E.K.B.)
| | - Efthimia K. Basdra
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (K.A.P.); (E.K.B.)
| | - Athanasios G. Papavassiliou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (K.A.P.); (E.K.B.)
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25
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Bhat N, Narayanan A, Fathzadeh M, Kahn M, Zhang D, Goedeke L, Neogi A, Cardone RL, Kibbey RG, Fernandez-Hernando C, Ginsberg HN, Jain D, Shulman GI, Mani A. Dyrk1b promotes hepatic lipogenesis by bypassing canonical insulin signaling and directly activating mTORC2 in mice. J Clin Invest 2022; 132:e153724. [PMID: 34855620 PMCID: PMC8803348 DOI: 10.1172/jci153724] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/24/2021] [Indexed: 11/24/2022] Open
Abstract
Mutations in Dyrk1b are associated with metabolic syndrome and nonalcoholic fatty liver disease in humans. Our investigations showed that DYRK1B levels are increased in the liver of patients with nonalcoholic steatohepatitis (NASH) and in mice fed with a high-fat, high-sucrose diet. Increasing Dyrk1b levels in the mouse liver enhanced de novo lipogenesis (DNL), fatty acid uptake, and triacylglycerol secretion and caused NASH and hyperlipidemia. Conversely, knockdown of Dyrk1b was protective against high-calorie-induced hepatic steatosis and fibrosis and hyperlipidemia. Mechanistically, Dyrk1b increased DNL by activating mTORC2 in a kinase-independent fashion. Accordingly, the Dyrk1b-induced NASH was fully rescued when mTORC2 was genetically disrupted. The elevated DNL was associated with increased plasma membrane sn-1,2-diacylglyerol levels and increased PKCε-mediated IRKT1150 phosphorylation, which resulted in impaired activation of hepatic insulin signaling and reduced hepatic glycogen storage. These findings provide insights into the mechanisms that underlie Dyrk1b-induced hepatic lipogenesis and hepatic insulin resistance and identify Dyrk1b as a therapeutic target for NASH and insulin resistance in the liver.
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Affiliation(s)
- Neha Bhat
- Cardiovascular Research Center, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Anand Narayanan
- Cardiovascular Research Center, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Mohsen Fathzadeh
- Department of Pediatrics, Stanford University, Palo Alto, California, USA
| | - Mario Kahn
- Yale Diabetes Research Center, Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Dongyan Zhang
- Yale Diabetes Research Center, Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Leigh Goedeke
- Yale Diabetes Research Center, Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Arpita Neogi
- Cardiovascular Research Center, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Rebecca L. Cardone
- Yale Diabetes Research Center, Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Richard G. Kibbey
- Yale Diabetes Research Center, Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | | | - Henry N. Ginsberg
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | | | - Gerald I. Shulman
- Yale Diabetes Research Center, Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Arya Mani
- Cardiovascular Research Center, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
- Department of Genetics, Yale School of Medicine, New Haven, Connecticut, USA
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Vallée A, Lecarpentier Y, Vallée JN. The Key Role of the WNT/β-Catenin Pathway in Metabolic Reprogramming in Cancers under Normoxic Conditions. Cancers (Basel) 2021; 13:cancers13215557. [PMID: 34771718 PMCID: PMC8582658 DOI: 10.3390/cancers13215557] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary The canonical WNT/β-catenin pathway is upregulated in cancers and plays a major role in proliferation, invasion, apoptosis and angiogenesis. Recent studies have shown that cancer processes are involved under normoxic conditions. These findings completely change the way of approaching the study of the cancer process. In this review, we focus on the fact that, under normoxic conditions, the overstimulation of the WNT/β-catenin pathway leads to modifications in the tumor micro-environment and the activation of the Warburg effect, i.e., aerobic glycolysis, autophagy and glutaminolysis, which in turn participate in tumor growth. Abstract The canonical WNT/β-catenin pathway is upregulated in cancers and plays a major role in proliferation, invasion, apoptosis and angiogenesis. Nuclear β-catenin accumulation is associated with cancer. Hypoxic mechanisms lead to the activation of the hypoxia-inducible factor (HIF)-1α, promoting glycolytic and energetic metabolism and angiogenesis. However, HIF-1α is degraded by the HIF prolyl hydroxylase under normoxia, conditions under which the WNT/β-catenin pathway can activate HIF-1α. This review is therefore focused on the interaction between the upregulated WNT/β-catenin pathway and the metabolic processes underlying cancer mechanisms under normoxic conditions. The WNT pathway stimulates the PI3K/Akt pathway, the STAT3 pathway and the transduction of WNT/β-catenin target genes (such as c-Myc) to activate HIF-1α activity in a hypoxia-independent manner. In cancers, stimulation of the WNT/β-catenin pathway induces many glycolytic enzymes, which in turn induce metabolic reprogramming, known as the Warburg effect or aerobic glycolysis, leading to lactate overproduction. The activation of the Wnt/β-catenin pathway induces gene transactivation via WNT target genes, c-Myc and cyclin D1, or via HIF-1α. This in turn encodes aerobic glycolysis enzymes, including glucose transporter, hexokinase 2, pyruvate kinase M2, pyruvate dehydrogenase kinase 1 and lactate dehydrogenase-A, leading to lactate production. The increase in lactate production is associated with modifications to the tumor microenvironment and tumor growth under normoxic conditions. Moreover, increased lactate production is associated with overexpression of VEGF, a key inducer of angiogenesis. Thus, under normoxic conditions, overstimulation of the WNT/β-catenin pathway leads to modifications of the tumor microenvironment and activation of the Warburg effect, autophagy and glutaminolysis, which in turn participate in tumor growth.
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Affiliation(s)
- Alexandre Vallée
- Department of Clinical Research and Innovation (DRCI), Foch Hospital, 92150 Suresnes, France
- Correspondence:
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l’Est Francilien (GHEF), 6-8 Rue Saint-Fiacre, 77100 Meaux, France;
| | - Jean-Noël Vallée
- Centre Hospitalier Universitaire (CHU) Amiens Picardie, Université Picardie Jules Verne (UPJV), 80054 Amiens, France;
- Laboratoire de Mathématiques et Applications (LMA), UMR, CNRS 7348, Université de Poitiers, 86000 Poitiers, France
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Implications of Phosphoinositide 3-Kinase-Akt (PI3K-Akt) Pathway in the Pathogenesis of Alzheimer's Disease. Mol Neurobiol 2021; 59:354-385. [PMID: 34699027 DOI: 10.1007/s12035-021-02611-7] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/19/2021] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is the foremost type of dementia that afflicts considerable morbidity and mortality in aged population. Several transcription molecules, pathways, and molecular mechanisms such as oxidative stress, inflammation, autophagy, and immune system interact in a multifaceted way that disrupt physiological processes (cell growth, differentiation, survival, lipid and energy metabolism, endocytosis) leading to apoptosis, tauopathy, β-amyloidopathy, neuron, and synapse loss, which play an important role in AD pathophysiology. Despite of stupendous advancements in pathogenic mechanisms, treatment of AD is still a nightmare in the field of medicine. There is compelling urgency to find not only symptomatic but effective disease-modifying therapies. Recently, phosphoinositide 3-kinase (PI3K) and Akt are identified as a pathway triggered by diverse stimuli, including insulin, growth factors, cytokines, and cellular stress, that link amyloid-β, neurofibrillary tangles, and brain atrophy. The present review aims to explore and analyze the role of PI3K-Akt pathway in AD and agents which may modulate Akt and have therapeutic prospects in AD. The literature was researched using keywords "PI3K-Akt" and "Alzheimer's disease" from PubMed, Web of Science, Bentham, Science Direct, Springer Nature, Scopus, and Google Scholar databases including books. Articles published from 1992 to 2021 were prioritized and analyzed for their strengths and limitations, and most appropriate ones were selected for the purpose of review. PI3K-Akt pathway regulates various biological processes such as cell proliferation, motility, growth, survival, and metabolic functions, and inhibits many neurotoxic mechanisms. Furthermore, experimental data indicate that PI3K-Akt signaling might be an important therapeutic target in treatment of AD.
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28
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Tago K, Ohta S, Aoki-Ohmura C, Funakoshi-Tago M, Sashikawa M, Matsui T, Miyamoto Y, Wada T, Oshio T, Komine M, Matsugi J, Furukawa Y, Ohtsuki M, Yamauchi J, Yanagisawa K. K15 promoter-driven enforced expression of NKIRAS exhibits tumor suppressive activity against the development of DMBA/TPA-induced skin tumors. Sci Rep 2021; 11:20658. [PMID: 34667224 PMCID: PMC8526694 DOI: 10.1038/s41598-021-00200-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/01/2021] [Indexed: 12/17/2022] Open
Abstract
NKIRAS1 and NKIRAS2 (also called as κB-Ras) were identified as members of the atypical RAS family that suppress the transcription factor NF-κB. However, their function in carcinogenesis is still controversial. To clarify how NKIRAS acts on cellular transformation, we generated transgenic mice in which NKIRAS2 was forcibly expressed using a cytokeratin 15 (K15) promoter, which is mainly activated in follicle bulge cells. The ectopic expression of NKIRAS2 was mainly detected in follicle bulges of transgenic mice with NKIRAS2 but not in wild type mice. K15 promoter-driven expression of NKIRAS2 failed to affect the development of epidermis, which was evaluated using the expression of K10, K14, K15 and filaggrin. However, K15 promoter-driven expression of NKIRAS2 effectively suppressed the development of skin tumors induced by treatment with 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol 13-acetate (TPA). This observation suggested that NKIRAS seemed to function as a tumor suppressor in follicle bulges. However, in the case of oncogenic HRAS-driven cellular transformation of murine fibroblasts, knockdown of NKIRAS2 expression drastically suppressed HRAS-mutant-provoked cellular transformation, suggesting that NKIRAS2 was required for the cellular transformation of murine fibroblasts. Furthermore, moderate enforced expression of NKIRAS2 augmented oncogenic HRAS-provoked cellular transformation, whereas an excess NKIRAS2 expression converted its functional role into a tumor suppressive phenotype, suggesting that NKIRAS seemed to exhibit a biphasic bell-shaped enhancing effect on HRAS-mutant-provoked oncogenic activity. Taken together, the functional role of NKIRAS in carcinogenesis is most likely determined by not only cellular context but also its expression level.
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Affiliation(s)
- Kenji Tago
- Division of Structural Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan.
| | - Satoshi Ohta
- Division of Structural Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Chihiro Aoki-Ohmura
- Division of Structural Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Megumi Funakoshi-Tago
- Division of Hygienic Chemistry, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo, 105-8512, Japan
| | - Miho Sashikawa
- Department of Dermatology, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Takeshi Matsui
- Laboratory for Evolutionary Cell Biology of the Skin, School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo, 192-0982, Japan
| | - Yuki Miyamoto
- Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, 157-8535, Japan
| | - Taeko Wada
- Division of Stem Cell Regulation, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Tomoyuki Oshio
- Department of Dermatology, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Mayumi Komine
- Department of Dermatology, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Jitsuhiro Matsugi
- Division of Structural Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yusuke Furukawa
- Division of Stem Cell Regulation, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Mamitaro Ohtsuki
- Department of Dermatology, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Junji Yamauchi
- Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, 157-8535, Japan.,Laboratory of Molecular Neuroscience and Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan
| | - Ken Yanagisawa
- Division of Structural Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
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O'Reilly CL, Uranga S, Fluckey JD. Culprits or consequences: Understanding the metabolic dysregulation of muscle in diabetes. World J Biol Chem 2021; 12:70-86. [PMID: 34630911 PMCID: PMC8473417 DOI: 10.4331/wjbc.v12.i5.70] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/21/2021] [Accepted: 08/03/2021] [Indexed: 02/06/2023] Open
Abstract
The prevalence of type 2 diabetes (T2D) continues to rise despite the amount of research dedicated to finding the culprits of this debilitating disease. Skeletal muscle is arguably the most important contributor to glucose disposal making it a clear target in insulin resistance and T2D research. Within skeletal muscle there is a clear link to metabolic dysregulation during the progression of T2D but the determination of culprits vs consequences of the disease has been elusive. Emerging evidence in skeletal muscle implicates influential cross talk between a key anabolic regulatory protein, the mammalian target of rapamycin (mTOR) and its associated complexes (mTORC1 and mTORC2), and the well-described canonical signaling for insulin-stimulated glucose uptake. This new understanding of cellular signaling crosstalk has blurred the lines of what is a culprit and what is a consequence with regard to insulin resistance. Here, we briefly review the most recent understanding of insulin signaling in skeletal muscle, and how anabolic responses favoring anabolism directly impact cellular glucose disposal. This review highlights key cross-over interactions between protein and glucose regulatory pathways and the implications this may have for the design of new therapeutic targets for the control of glucoregulatory function in skeletal muscle.
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Affiliation(s)
| | - Selina Uranga
- Health and Kinesiology, Texas A&M University, TX 77843, United States
| | - James D Fluckey
- Health and Kinesiology, Texas A&M University, TX 77843, United States
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30
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Sanvee GM, Hitzfeld L, Bouitbir J, Krähenbühl S. mTORC2 is an important target for simvastatin-associated toxicity in C2C12 cells and mouse skeletal muscle - Roles of Rap1 geranylgeranylation and mitochondrial dysfunction. Biochem Pharmacol 2021; 192:114750. [PMID: 34461118 DOI: 10.1016/j.bcp.2021.114750] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 12/25/2022]
Abstract
Statins decrease the serum LDL-cholesterol concentration and reduce the risk for cardiovascular diseases but can cause myopathy, which may be related to mTORC inhibition. In the current study, we investigated which mTORC is inhibited by simvastatin and by which mechanisms. In C2C12 myoblasts and myotubes and mouse gastrocnemius, simvastatin was cytotoxic and inhibited S6rp and Akt Ser473 phosphorylation, indicating inhibition of mTORC1 and mTORC2, respectively. In contrast to simvastatin, the mTORC1 inhibitor rapamycin did not inhibit mTORC2 activity and was not cytotoxic. Like simvastatin, knock-down of Rictor, an essential component of mTORC2, impaired Akt Ser473 and S6rp phosphorylation and was cytotoxic for C2C12 myoblasts, suggesting that mTORC2 inhibition is an important myotoxic mechanism. The investigation of the mechanism of mTORC2 inhibition showed that simvastatin impaired Ras farnesylation, which was prevented by farnesol but without restoring mTORC2 activity. In comparison, Rap1 knock-down reduced mTORC2 activity and was cytotoxic for C2C12 myoblasts. Simvastatin impaired Rap1 geranylgeranylation and function, which was prevented by geranylgeraniol. In addition, simvastatin and the complex III inhibitor antimycin A caused mitochondrial superoxide accumulation and impaired the activity of mTORC2, which could partially be prevented by the antioxidant MitoTEMPO. In conclusion, mTORC2 inhibition is an important mechanism of simvastatin-induced myotoxicity. Simvastatin inhibits mTORC2 by impairing geranylgeranylation of Rap1 and by inducing mitochondrial dysfunction.
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Affiliation(s)
- Gerda M Sanvee
- Division of Clinical Pharmacology & Toxicology, University Hospital, Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland
| | - Leonie Hitzfeld
- Division of Clinical Pharmacology & Toxicology, University Hospital, Basel, Switzerland
| | - Jamal Bouitbir
- Division of Clinical Pharmacology & Toxicology, University Hospital, Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Division of Molecular and Systemic Toxicology, Department of Pharmaceutical Sciences, University of Basel, Switzerland; Swiss Centre for Applied Human Research (SCAHT), Switzerland
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology & Toxicology, University Hospital, Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Swiss Centre for Applied Human Research (SCAHT), Switzerland.
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31
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Madhivanan K, Ramadesikan S, Hsieh WC, Aguilar MC, Hanna CB, Bacallao RL, Aguilar RC. Lowe syndrome patient cells display mTOR- and RhoGTPase-dependent phenotypes alleviated by rapamycin and statins. Hum Mol Genet 2021; 29:1700-1715. [PMID: 32391547 DOI: 10.1093/hmg/ddaa086] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/20/2020] [Accepted: 05/04/2020] [Indexed: 12/25/2022] Open
Abstract
Lowe syndrome (LS) is an X-linked developmental disease characterized by cognitive deficiencies, bilateral congenital cataracts and renal dysfunction. Unfortunately, this disease leads to the early death of affected children often due to kidney failure. Although this condition was first described in the early 1950s and the affected gene (OCRL1) was identified in the early 1990s, its pathophysiological mechanism is not fully understood and there is no LS-specific cure available to patients. Here we report two important signaling pathways affected in LS patient cells. While RhoGTPase signaling abnormalities led to adhesion and spreading defects as compared to normal controls, PI3K/mTOR hyperactivation interfered with primary cilia assembly (scenario also observed in other ciliopathies with compromised kidney function). Importantly, we identified two FDA-approved drugs able to ameliorate these phenotypes. Specifically, statins mitigated adhesion and spreading abnormalities while rapamycin facilitated ciliogenesis in LS patient cells. However, no single drug was able to alleviate both phenotypes. Based on these and other observations, we speculate that Ocrl1 has dual, independent functions supporting proper RhoGTPase and PI3K/mTOR signaling. Therefore, this study suggest that Ocrl1-deficiency leads to signaling defects likely to require combinatorial drug treatment to suppress patient phenotypes and symptoms.
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Affiliation(s)
- Kayalvizhi Madhivanan
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Swetha Ramadesikan
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Wen-Chieh Hsieh
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Mariana C Aguilar
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Claudia B Hanna
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Robert L Bacallao
- Division of Nephrology, Indiana University School of Medicine, 340 W 10th St #6200, Indianapolis, IN 46202, USA
| | - R Claudio Aguilar
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
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32
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Ghomlaghi M, Hart A, Hoang N, Shin S, Nguyen LK. Feedback, Crosstalk and Competition: Ingredients for Emergent Non-Linear Behaviour in the PI3K/mTOR Signalling Network. Int J Mol Sci 2021; 22:6944. [PMID: 34203293 PMCID: PMC8267830 DOI: 10.3390/ijms22136944] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/20/2021] [Accepted: 06/23/2021] [Indexed: 12/15/2022] Open
Abstract
The PI3K/mTOR signalling pathway plays a central role in the governing of cell growth, survival and metabolism. As such, it must integrate and decode information from both external and internal sources to guide efficient decision-making by the cell. To facilitate this, the pathway has evolved an intricate web of complex regulatory mechanisms and elaborate crosstalk with neighbouring signalling pathways, making it a highly non-linear system. Here, we describe the mechanistic biological details that underpin these regulatory mechanisms, covering a multitude of negative and positive feedback loops, feed-forward loops, competing protein interactions, and crosstalk with major signalling pathways. Further, we highlight the non-linear and dynamic network behaviours that arise from these regulations, uncovered through computational and experimental studies. Given the pivotal role of the PI3K/mTOR network in cellular homeostasis and its frequent dysregulation in pathologies including cancer and diabetes, a coherent and systems-level understanding of the complex regulation and consequential dynamic signalling behaviours within this network is imperative for advancing biology and development of new therapeutic approaches.
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Affiliation(s)
- Milad Ghomlaghi
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia; (M.G.); (A.H.); (N.H.); (S.S.)
- Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Anthony Hart
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia; (M.G.); (A.H.); (N.H.); (S.S.)
- Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Nhan Hoang
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia; (M.G.); (A.H.); (N.H.); (S.S.)
| | - Sungyoung Shin
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia; (M.G.); (A.H.); (N.H.); (S.S.)
- Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Lan K. Nguyen
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia; (M.G.); (A.H.); (N.H.); (S.S.)
- Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
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Cortada M, Levano S, Bodmer D. mTOR Signaling in the Inner Ear as Potential Target to Treat Hearing Loss. Int J Mol Sci 2021; 22:ijms22126368. [PMID: 34198685 PMCID: PMC8232255 DOI: 10.3390/ijms22126368] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 12/14/2022] Open
Abstract
Hearing loss affects many people worldwide and occurs often as a result of age, ototoxic drugs and/or excessive noise exposure. With a growing number of elderly people, the number of people suffering from hearing loss will also increase in the future. Despite the high number of affected people, for most patients there is no curative therapy for hearing loss and hearing aids or cochlea implants remain the only option. Important treatment approaches for hearing loss include the development of regenerative therapies or the inhibition of cell death/promotion of cell survival pathways. The mammalian target of rapamycin (mTOR) pathway is a central regulator of cell growth, is involved in cell survival, and has been shown to be implicated in many age-related diseases. In the inner ear, mTOR signaling has also started to gain attention recently. In this review, we will emphasize recent discoveries of mTOR signaling in the inner ear and discuss implications for possible treatments for hearing restoration.
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Affiliation(s)
- Maurizio Cortada
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland; (M.C.); (S.L.)
| | - Soledad Levano
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland; (M.C.); (S.L.)
| | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland; (M.C.); (S.L.)
- Clinic for Otorhinolaryngology, Head and Neck Surgery, University of Basel Hospital, Petersgraben 4, 4031 Basel, Switzerland
- Correspondence: ; Tel.: +41-61-328-76-03
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Vallée A, Lecarpentier Y, Vallée JN. Opposed Interplay between IDH1 Mutations and the WNT/β-Catenin Pathway: Added Information for Glioma Classification. Biomedicines 2021; 9:biomedicines9060619. [PMID: 34070746 PMCID: PMC8229353 DOI: 10.3390/biomedicines9060619] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 12/23/2022] Open
Abstract
Gliomas are the main common primary intraparenchymal brain tumor in the central nervous system (CNS), with approximately 7% of the death caused by cancers. In the WHO 2016 classification, molecular dysregulations are part of the definition of particular brain tumor entities for the first time. Nevertheless, the underlying molecular mechanisms remain unclear. Several studies have shown that 75% to 80% of secondary glioblastoma (GBM) showed IDH1 mutations, whereas only 5% of primary GBM have IDH1 mutations. IDH1 mutations lead to better overall survival in gliomas patients. IDH1 mutations are associated with lower stimulation of the HIF-1α a, aerobic glycolysis and angiogenesis. The stimulation of HIF-1α and the process of angiogenesis appears to be activated only when hypoxia occurs in IDH1-mutated gliomas. In contrast, the observed upregulation of the canonical WNT/β-catenin pathway in gliomas is associated with proliferation, invasion, aggressive-ness and angiogenesis.. Molecular pathways of the malignancy process are involved in early stages of WNT/β-catenin pathway-activated-gliomas, and this even under normoxic conditions. IDH1 mutations lead to decreased activity of the WNT/β-catenin pathway and its enzymatic targets. The opposed interplay between IDH1 mutations and the canonical WNT/β-catenin pathway in gliomas could participate in better understanding of the observed evolution of different tumors and could reinforce the glioma classification.
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Affiliation(s)
- Alexandre Vallée
- Department of Clinical Research and Innovation, Foch Hospital, 92150 Suresnes, France
- Correspondence:
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l’Est Francilien (GHEF), 77100 Meaux, France;
| | - Jean-Noël Vallée
- Centre Hospitalier Universitaire (CHU) Amiens Picardie, Université Picardie Jules Verne (UPJV), 80000 Amiens, France;
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, 86000 Poitiers, France
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Werlen G, Jain R, Jacinto E. MTOR Signaling and Metabolism in Early T Cell Development. Genes (Basel) 2021; 12:genes12050728. [PMID: 34068092 PMCID: PMC8152735 DOI: 10.3390/genes12050728] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/10/2021] [Accepted: 05/10/2021] [Indexed: 12/12/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) controls cell fate and responses via its functions in regulating metabolism. Its role in controlling immunity was unraveled by early studies on the immunosuppressive properties of rapamycin. Recent studies have provided insights on how metabolic reprogramming and mTOR signaling impact peripheral T cell activation and fate. The contribution of mTOR and metabolism during early T-cell development in the thymus is also emerging and is the subject of this review. Two major T lineages with distinct immune functions and peripheral homing organs diverge during early thymic development; the αβ- and γδ-T cells, which are defined by their respective TCR subunits. Thymic T-regulatory cells, which have immunosuppressive functions, also develop in the thymus from positively selected αβ-T cells. Here, we review recent findings on how the two mTOR protein complexes, mTORC1 and mTORC2, and the signaling molecules involved in the mTOR pathway are involved in thymocyte differentiation. We discuss emerging views on how metabolic remodeling impacts early T cell development and how this can be mediated via mTOR signaling.
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Lee EJ, Neppl RL. Influence of Age on Skeletal Muscle Hypertrophy and Atrophy Signaling: Established Paradigms and Unexpected Links. Genes (Basel) 2021; 12:genes12050688. [PMID: 34063658 PMCID: PMC8147613 DOI: 10.3390/genes12050688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/16/2022] Open
Abstract
Skeletal muscle atrophy in an inevitable occurrence with advancing age, and a consequence of disease including cancer. Muscle atrophy in the elderly is managed by a regimen of resistance exercise and increased protein intake. Understanding the signaling that regulates muscle mass may identify potential therapeutic targets for the prevention and reversal of muscle atrophy in metabolic and neuromuscular diseases. This review covers the major anabolic and catabolic pathways that regulate skeletal muscle mass, with a focus on recent progress and potential new players.
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Lv Z, Yue Z, Shao Y, Li C, Zhao X, Guo M. mTORC2/Rictor is essential for coelomocyte endocytosis in Apostichopus japonicus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 118:104000. [PMID: 33444645 DOI: 10.1016/j.dci.2021.104000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Endocytosis plays an important role in the immune defence systems of invertebrates through the interaction between the mechanical target of rapamycin complex 2 (mTORC2) and the AGC kinase family. Rictor is the most important unique subunit protein of mTORC2 and is thought to regulate almost all functions of mTORC2, including endocytosis. In the present study, a novel invertebrate Rictor homologue was identified from Apostichopus japonicus (designated as AjRictor) via the rapid amplification of cDNA ends (RACE). Spatial expression analysis indicated that AjRictor is ubiquitously expressed in all the examined tissues and has the highest transcript level in coelomocytes. Vibrio splendidus challenge in vivo and lipopolysaccharide (LPS) exposure in vitro could remarkably up-regulate the messenger RNA (mRNA) expression of AjRictor compared with the control group. AjRictor knockdown by 0.49- and 0.69-fold resulted in the significant decrease in endocytosis rate by 0.53- (P < 0.01) and 0.59-fold (P < 0.01) in vivo and in vitro compared with the control group, respectively. Similarly, the treatment of coelomocytes with rapamycin for 24 h and the destruction of the assembly of mTORC2 markedly decreased the endocytosis rate of the coelomocytes by 35.92% (P < 0.05). We detected the expression levels of endocytosis-related molecular markers after AjRictor knockdown and rapamycin treatment to further study the molecular mechanism between mTORC2 and endocytosis. Our results showed that AGC kinase family members (PKCα and Pan1) and the phosphorylation level of AktS473 were remarkably decreased after reducing mTORC2 activity; thus, mTORC2/Rictor plays a key role in the immune regulation of endocytosis in coelomocytes. Our current study indicates that mTORC2/Rictor is involved in the coelomocyte endocytosis of sea cucumber and plays an essential regulation role in defending pathogen invasion.
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Affiliation(s)
- Zhimeng Lv
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Zongxu Yue
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Yina Shao
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China.
| | - Chenghua Li
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
| | - Xuelin Zhao
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Ming Guo
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
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Glucagon transiently stimulates mTORC1 by activation of an EPAC/Rap1 signaling axis. Cell Signal 2021; 84:110010. [PMID: 33872697 PMCID: PMC8169602 DOI: 10.1016/j.cellsig.2021.110010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/22/2022]
Abstract
Activation of the protein kinase mechanistic target of rapamycin (mTOR) in both complexes 1 and 2 (mTORC1/2) in the liver is repressed during fasting and rapidly stimulated in response to a meal. The effect of feeding on hepatic mTORC1/2 is attributed to an increase in plasma levels of nutrients, such as amino acids, and insulin. By contrast, fasting is associated with elevated plasma levels of glucagon, which is conventionally viewed as having a counter-regulatory role to insulin. More recently an expanded role for glucagon action in post-prandial metabolism has been demonstrated. Herein we investigated the impact of insulin and glucagon on mTORC1/2 activation. In H4IIE and HepG2 cultures, insulin enhanced phosphorylation of the mTORC1 substrates S6K1 and 4E-BP1. Surprisingly, the effect of glucagon on mTORC1 was biphasic, wherein there was an acute increase in phosphorylation of S6K1 and 4E-BP1 over the first hour of exposure, followed by latent suppression. The transient stimulatory effect of glucagon on mTORC1 was not additive with insulin, suggesting convergent signaling. Glucagon enhanced cAMP levels and mTORC1 stimulation required activation of the glucagon receptor, PI3K/Akt, and exchange protein activated by cAMP (EPAC). EPAC acts as the guanine nucleotide exchange factor for the small GTPase Rap1. Rap1 expression enhanced S6K1 phosphorylation and glucagon addition to culture medium promoted Rap1-GTP loading. Signaling through mTORC1 acts to regulate protein synthesis and we found that glucagon promoted an EPAC-dependent increase in protein synthesis. Overall, the findings support that glucagon elicits acute activation of mTORC1/2 by an EPAC-dependent increase in Rap1-GTP.
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Adefemi F, Fruman DA, Marshall AJ. A Case for Phosphoinositide 3-Kinase-Targeted Therapy for Infectious Disease. THE JOURNAL OF IMMUNOLOGY 2021; 205:3237-3245. [PMID: 33288538 DOI: 10.4049/jimmunol.2000599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/22/2020] [Indexed: 12/19/2022]
Abstract
PI3Ks activate critical signaling cascades and have multifaceted regulatory functions in the immune system. Loss-of-function and gain-of-function mutations in the PI3Kδ isoform have revealed that this enzyme can substantially impact immune responses to infectious agents and their products. Moreover, reports garnered from decades of infectious disease studies indicate that pharmacologic inhibition of the PI3K pathway could potentially be effective in limiting the growth of certain microbes via modulation of the immune system. In this review, we briefly highlight the development and applications of PI3K inhibitors and summarize data supporting the concept that PI3Kδ inhibitors initially developed for oncology have immune regulatory potential that could be exploited to improve the control of some infectious diseases. This repurposing of existing kinase inhibitors could lay the foundation for alternative infectious disease therapy using available therapeutic agents.
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Affiliation(s)
- Folayemi Adefemi
- Department of Immunology, Rady Faculty of Health Sciences, University of Manitoba, R3E-0T5 Winnipeg, Manitoba, Canada
| | - David A Fruman
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; and.,Institute for Immunology, University of California, Irvine, CA 92697
| | - Aaron J Marshall
- Department of Immunology, Rady Faculty of Health Sciences, University of Manitoba, R3E-0T5 Winnipeg, Manitoba, Canada;
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Abstract
Cells metabolize nutrients for biosynthetic and bioenergetic needs to fuel growth and proliferation. The uptake of nutrients from the environment and their intracellular metabolism is a highly controlled process that involves cross talk between growth signaling and metabolic pathways. Despite constant fluctuations in nutrient availability and environmental signals, normal cells restore metabolic homeostasis to maintain cellular functions and prevent disease. A central signaling molecule that integrates growth with metabolism is the mechanistic target of rapamycin (mTOR). mTOR is a protein kinase that responds to levels of nutrients and growth signals. mTOR forms two protein complexes, mTORC1, which is sensitive to rapamycin, and mTORC2, which is not directly inhibited by this drug. Rapamycin has facilitated the discovery of the various functions of mTORC1 in metabolism. Genetic models that disrupt either mTORC1 or mTORC2 have expanded our knowledge of their cellular, tissue, as well as systemic functions in metabolism. Nevertheless, our knowledge of the regulation and functions of mTORC2, particularly in metabolism, has lagged behind. Since mTOR is an important target for cancer, aging, and other metabolism-related pathologies, understanding the distinct and overlapping regulation and functions of the two mTOR complexes is vital for the development of more effective therapeutic strategies. This review discusses the key discoveries and recent findings on the regulation and metabolic functions of the mTOR complexes. We highlight findings from cancer models but also discuss other examples of the mTOR-mediated metabolic reprogramming occurring in stem and immune cells, type 2 diabetes/obesity, neurodegenerative disorders, and aging.
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Affiliation(s)
- Angelia Szwed
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Eugene Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
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Finding new edges: systems approaches to MTOR signaling. Biochem Soc Trans 2021; 49:41-54. [PMID: 33544134 PMCID: PMC7924996 DOI: 10.1042/bst20190730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 12/23/2020] [Accepted: 01/05/2021] [Indexed: 11/17/2022]
Abstract
Cells have evolved highly intertwined kinase networks to finely tune cellular homeostasis to the environment. The network converging on the mechanistic target of rapamycin (MTOR) kinase constitutes a central hub that integrates metabolic signals and adapts cellular metabolism and functions to nutritional changes and stress. Feedforward and feedback loops, crosstalks and a plethora of modulators finely balance MTOR-driven anabolic and catabolic processes. This complexity renders it difficult — if not impossible — to intuitively decipher signaling dynamics and network topology. Over the last two decades, systems approaches have emerged as powerful tools to simulate signaling network dynamics and responses. In this review, we discuss the contribution of systems studies to the discovery of novel edges and modulators in the MTOR network in healthy cells and in disease.
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Sciarretta S, Forte M, Frati G, Sadoshima J. The complex network of mTOR signaling in the heart. Cardiovasc Res 2021; 118:424-439. [PMID: 33512477 DOI: 10.1093/cvr/cvab033] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/13/2020] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) integrates several intracellular and extracellular signals involved in the regulation of anabolic and catabolic processes. mTOR assembles into two macromolecular complexes, named mTORC1 and mTORC2, which have different regulators, substrates and functions. Studies of gain- and loss-of-function animal models of mTOR signaling revealed that mTORC1/2 elicit both adaptive and maladaptive functions in the cardiovascular system. Both mTORC1 and mTORC2 are indispensable for driving cardiac development and cardiac adaption to stress, such as pressure overload. However, persistent and deregulated mTORC1 activation in the heart is detrimental during stress and contributes to the development and progression of cardiac remodeling and genetic and metabolic cardiomyopathies. In this review, we discuss the latest findings regarding the role of mTOR in the cardiovascular system, both under basal conditions and during stress, such as pressure overload, ischemia and metabolic stress. Current data suggest that mTOR modulation may represent a potential therapeutic strategy for the treatment of cardiac diseases.
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Affiliation(s)
- Sebastiano Sciarretta
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.,IRCCS Neuromed, Pozzilli (IS), Italy
| | | | - Giacomo Frati
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.,IRCCS Neuromed, Pozzilli (IS), Italy
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA
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Kang W, Zhang K, Tong T, Park T. Improved Glucose Intolerance through a Distinct Mouse Olfactory Receptor 23-Induced Signaling Pathway Mediating Glucose Uptake in Myotubes and Adipocytes. Mol Nutr Food Res 2020; 64:e1901329. [PMID: 32918394 DOI: 10.1002/mnfr.201901329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
SCOPE It is aimed to determine the role of mouse olfactory receptor 23 (MOR23) in regulation of glucose uptake in myotubes and adipocytes and investigate whether administration of a possible MOR23 ligand, α-cedrene, attenuates the high fat diet (HFD)-induced glucose intolerance by enhancing the OR-mediated signaling pathway in mice. METHODS AND RESULTS MOR23 is genetically inactivated by specific small interfering RNA in C2C12 myotubes and 3T3-L1 adipocytes and stimulated with α-cedrene under both basal and insulin-stimulated conditions. In addition, Male C57BL/6N mice are fed a normal diet, HFD, or HFD supplemented with 0.2% α-cedrene. In C2C12 myotubes and 3T3-L1 adipocytes, genetic inactivation of MOR23 significantly decrease glucose uptake and MOR23 downstream signaling under both basal and insulin-stimulated conditions. On the other hand, α-cedrene-mediated MOR23 stimulation results in increased glucose uptake and upregulation of MOR23 signaling molecules, absent in MOR23-depleted myotubes and adipocytes. Moreover, in mice, α-cedrene administration ameliorates HFD-induced glucose intolerance. Activation of MOR23 signaling cascade is also confirmed in basal and insulin stimulated skeletal muscles and adipose tissues of α-cedrene-treated mice. CONCLUSIONS These findings suggest that MOR23 is a novel factor for the regulation of glucose uptake and whole-body glucose homeostasis and has therapeutic potential for diabetes treatment.
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Affiliation(s)
- Wesuk Kang
- Department of Food and Nutrition, Brain Korea 21 PLUS Project, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Kelun Zhang
- Department of Food and Nutrition, Brain Korea 21 PLUS Project, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Tao Tong
- Department of Food and Nutrition, Brain Korea 21 PLUS Project, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Taesun Park
- Department of Food and Nutrition, Brain Korea 21 PLUS Project, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
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Koganti R, Suryawanshi R, Shukla D. Heparanase, cell signaling, and viral infections. Cell Mol Life Sci 2020; 77:5059-5077. [PMID: 32462405 PMCID: PMC7252873 DOI: 10.1007/s00018-020-03559-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/17/2020] [Accepted: 05/22/2020] [Indexed: 12/13/2022]
Abstract
Heparanase (HPSE) is a multifunctional protein endowed with many non-enzymatic functions and a unique enzymatic activity as an endo-β-D-glucuronidase. The latter allows it to serve as a key modulator of extracellular matrix (ECM) via a well-regulated cleavage of heparan sulfate side chains of proteoglycans at cell surfaces. The cleavage and associated changes at the ECM cause release of multiple signaling molecules with important cellular and pathological functions. New and emerging data suggest that both enzymatic as well as non-enzymatic functions of HPSE are important for health and illnesses including viral infections and virally induced cancers. This review summarizes recent findings on the roles of HPSE in activation, inhibition, or bioavailability of key signaling molecules such as AKT, VEGF, MAPK-ERK, and EGFR, which are known regulators of common viral infections in immune and non-immune cell types. Altogether, our review provides a unique overview of HPSE in cell-survival signaling pathways and how they relate to viral infections.
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Affiliation(s)
- Raghuram Koganti
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St, Chicago, IL, 60612, USA
| | - Rahul Suryawanshi
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St, Chicago, IL, 60612, USA
| | - Deepak Shukla
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St, Chicago, IL, 60612, USA.
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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mTORC2 Assembly Is Regulated by USP9X-Mediated Deubiquitination of RICTOR. Cell Rep 2020; 33:108564. [PMID: 33378666 DOI: 10.1016/j.celrep.2020.108564] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 10/14/2020] [Accepted: 12/07/2020] [Indexed: 11/23/2022] Open
Abstract
The mechanistic target of rapamycin complex 2 (mTORC2) controls cell metabolism and survival in response to environmental inputs. Dysregulation of mTORC2 signaling has been linked to diverse human diseases, including cancer and metabolic disorders, highlighting the importance of a tightly controlled mTORC2. While mTORC2 assembly is a critical determinant of its activity, the factors regulating this event are not well understood, and it is unclear whether this process is regulated by growth factors. Here, we present data, from human cell lines and mice, describing a mechanism by which growth factors regulate ubiquitin-specific protease 9X (USP9X) deubiquitinase to stimulate mTORC2 assembly and activity. USP9X removes Lys63-linked ubiquitin from RICTOR to promote its interaction with mTOR, thereby facilitating mTORC2 signaling. As mTORC2 is central for cellular homeostasis, understanding the mechanisms regulating mTORC2 activation toward its downstream targets is vital for our understanding of physiological processes and for developing new therapeutic strategies in pathology.
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46
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Gui Y, Dai C. mTOR Signaling in Kidney Diseases. KIDNEY360 2020; 1:1319-1327. [PMID: 35372878 PMCID: PMC8815517 DOI: 10.34067/kid.0003782020] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/02/2020] [Indexed: 04/27/2023]
Abstract
The mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, is crucial in regulating cell growth, metabolism, proliferation, and survival. Under physiologic conditions, mTOR signaling maintains podocyte and tubular cell homeostasis. In AKI, activation of mTOR signaling in tubular cells and interstitial fibroblasts promotes renal regeneration and repair. However, constitutive activation of mTOR signaling in kidneys results in the initiation and progression of glomerular hypertrophy, interstitial fibrosis, polycystic kidney disease, and renal cell carcinoma. Here, we summarize the recent studies about mTOR signaling in renal physiology and injury, and discuss the possibility of its use as a therapeutic target for kidney diseases.
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Affiliation(s)
- Yuan Gui
- Department of Nephrology, University of Connecticut Health Center, Farmington, Connecticut
| | - Chunsun Dai
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
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Abstract
The Ras oncogene is notoriously difficult to target with specific therapeutics. Consequently, there is interest to better understand the Ras signaling pathways to identify potential targetable effectors. Recently, the mechanistic target of rapamycin complex 2 (mTORC2) was identified as an evolutionarily conserved Ras effector. mTORC2 regulates essential cellular processes, including metabolism, survival, growth, proliferation and migration. Moreover, increasing evidence implicate mTORC2 in oncogenesis. Little is known about the regulation of mTORC2 activity, but proposed mechanisms include a role for phosphatidylinositol (3,4,5)-trisphosphate - which is produced by class I phosphatidylinositol 3-kinases (PI3Ks), well-characterized Ras effectors. Therefore, the relationship between Ras, PI3K and mTORC2, in both normal physiology and cancer is unclear; moreover, seemingly conflicting observations have been reported. Here, we review the evidence on potential links between Ras, PI3K and mTORC2. Interestingly, data suggest that Ras and PI3K are both direct regulators of mTORC2 but that they act on distinct pools of mTORC2: Ras activates mTORC2 at the plasma membrane, whereas PI3K activates mTORC2 at intracellular compartments. Consequently, we propose a model to explain how Ras and PI3K can differentially regulate mTORC2, and highlight the diversity in the mechanisms of mTORC2 regulation, which appear to be determined by the stimulus, cell type, and the molecularly and spatially distinct mTORC2 pools.
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Fu W, Hall MN. Regulation of mTORC2 Signaling. Genes (Basel) 2020; 11:E1045. [PMID: 32899613 PMCID: PMC7564249 DOI: 10.3390/genes11091045] [Citation(s) in RCA: 137] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian target of rapamycin (mTOR), a serine/threonine protein kinase and a master regulator of cell growth and metabolism, forms two structurally and functionally distinct complexes, mTOR complex 1 (mTORC1) and mTORC2. While mTORC1 signaling is well characterized, mTORC2 is relatively poorly understood. mTORC2 appears to exist in functionally distinct pools, but few mTORC2 effectors/substrates have been identified. Here, we review recent advances in our understanding of mTORC2 signaling, with particular emphasis on factors that control mTORC2 activity.
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Affiliation(s)
- Wenxiang Fu
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming 650500, China
- Biozentrum, University of Basel, CH4056 Basel, Switzerland;
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Chou PC, Rajput S, Zhao X, Patel C, Albaciete D, Oh WJ, Daguplo HQ, Patel N, Su B, Werlen G, Jacinto E. mTORC2 Is Involved in the Induction of RSK Phosphorylation by Serum or Nutrient Starvation. Cells 2020; 9:E1567. [PMID: 32605013 PMCID: PMC7408474 DOI: 10.3390/cells9071567] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 12/26/2022] Open
Abstract
Cells adjust to nutrient fluctuations to restore metabolic homeostasis. The mechanistic target of rapamycin (mTOR) complex 2 responds to nutrient levels and growth signals to phosphorylate protein kinases belonging to the AGC (Protein Kinases A,G,C) family such as Akt and PKC. Phosphorylation of these AGC kinases at their conserved hydrophobic motif (HM) site by mTORC2 enhances their activation and mediates the functions of mTORC2 in cell growth and metabolism. Another AGC kinase family member that is known to undergo increased phosphorylation at the homologous HM site (Ser380) is the p90 ribosomal S6 kinase (RSK). Phosphorylation at Ser380 is facilitated by the activation of the mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) in response to growth factor stimulation. Here, we demonstrate that optimal phosphorylation of RSK at this site requires an intact mTORC2. We also found that RSK is robustly phosphorylated at Ser380 upon nutrient withdrawal or inhibition of glycolysis, conditions that increase mTORC2 activation. However, pharmacological inhibition of mTOR did not abolish RSK phosphorylation at Ser380, indicating that mTOR catalytic activity is not required for this phosphorylation. Since RSK and SIN1β colocalize at the membrane during serum restimulation and acute glutamine withdrawal, mTORC2 could act as a scaffold to enhance RSK HM site phosphorylation. Among the known RSK substrates, the CCTβ subunit of the chaperonin containing TCP-1 (CCT) complex had defective phosphorylation in the absence of mTORC2. Our findings indicate that the mTORC2-mediated phosphorylation of the RSK HM site could confer RSK substrate specificity and reveal that RSK responds to nutrient fluctuations.
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Affiliation(s)
- Po-Chien Chou
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Swati Rajput
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Xiaoyun Zhao
- Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China; (X.Z.); (B.S.)
| | - Chadni Patel
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Danielle Albaciete
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Won Jun Oh
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Heineken Queen Daguplo
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Nikhil Patel
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Bing Su
- Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China; (X.Z.); (B.S.)
| | - Guy Werlen
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
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Bao HR, Chen JL, Li F, Zeng XL, Liu XJ. Relationship between PI3K/mTOR/RhoA pathway-regulated cytoskeletal rearrangements and phagocytic capacity of macrophages. ACTA ACUST UNITED AC 2020; 53:e9207. [PMID: 32520207 PMCID: PMC7279697 DOI: 10.1590/1414-431x20209207] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 03/26/2020] [Indexed: 12/02/2022]
Abstract
The objective of this study was to investigate the relationship between PI3K/mTOR/RhoA signaling regulated cytoskeletal rearrangements and phagocytic capacity of macrophages. RAW264.7 macrophages were divided into four groups; blank control, negative control, PI3K-RNAi, and mTOR-RNAi. The cytoskeletal changes in the macrophages were observed. Furthermore, the phagocytic capacity of macrophages against Escherichia coli is reported as mean fluorescence intensity (MFI) and percent phagocytosis. Transfection yielded 82.1 and 81.5% gene-silencing efficiencies against PI3K and mTOR, respectively. The PI3K-RNAi group had lower mRNA and protein expression levels of PI3K, mTOR, and RhoA than the blank and negative control groups (Р<0.01). The mTOR-RNAi group had lower mRNA and protein levels of mTOR and RhoA than the blank and the negative control groups (Р<0.01). Macrophages in the PI3K-RNAi group exhibited stiff and inflexible morphology with short, disorganized filopodia and reduced number of stress fibers. Macrophages in the mTOR-RNAi group displayed pronounced cellular deformations with long, dense filopodia and an increased number of stress fibers. The PI3K-RNAi group exhibited lower MFI and percent phagocytosis than blank and negative control groups, whereas the mTOR-RNAi group displayed higher MFI and percent phagocytosis than the blank and negative controls (Р<0.01). Before and after transfection, the mRNA and protein levels of PI3K were both positively correlated with mTOR and RhoA (Р<0.05), but the mRNA and protein levels of mTOR were negatively correlated with those of RhoA (Р<0.05). Changes in the phagocytic capacity of macrophages were associated with cytoskeletal rearrangements and were regulated by the PI3K/mTOR/RhoA signaling pathway.
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Affiliation(s)
- H R Bao
- Department of Gerontal Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
| | - J L Chen
- Department of Gerontal Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
| | - F Li
- Department of Gerontal Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
| | - X L Zeng
- Department of Gerontal Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
| | - X J Liu
- Department of Gerontal Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
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