• Excitotoxicity
• Glaucoma
• Ophthalmology
• Optic neuropathy
• Proteomics
• Retina

• Retinal Ganglion Cells/metabolism
• Retinal Ganglion Cells/pathology
• Animals
• Mice, Inbred C57BL
• Proteomics/methods
• Mice
• Optic Nerve Injuries/metabolism
• Optic Nerve Injuries/pathology
• Disease Models, Animal
• Nerve Crush
• Eye Proteins/metabolism
• Chromatography, Liquid
• Proteome/metabolism
• N-Methylaspartate/toxicity

• Excitotoxicity
• Glaucoma
• Ophthalmology
• Optic Neuropathy
• Proteomics
• Retina

• R01 EY027763 NEI NIH HHS

• Biological sciences
• Molecular biology
• Physiology
• Zoology

• cell death in the nervous system
• astrocyte

• Animals
• Astrocytes/metabolism
• Ischemia/metabolism
• Lipocalin-2/genetics
• Lipocalin-2/metabolism
• Mice
• NADPH Oxidases/metabolism
• Sodium-Hydrogen Exchangers/genetics
• Sodium-Hydrogen Exchangers/metabolism
• Stroke/metabolism

• R01 NS110755 NINDS NIH HHS
• RF1 AG059610 NIA NIH HHS
• R01 NS118747 NINDS NIH HHS
• S10 OD016236 NIH HHS
• R01 NS125490 NINDS NIH HHS
• R01 AG078728 NIA NIH HHS
• RF1 AG057882 NIA NIH HHS
• U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and Stroke (NINDS)

• Endoplasmic reticulum
• Glycolysis
• Metabolism
• Mitochondria
• Pluripotent stem cells

• GRP78
• GRP78 autoantibodies
• GRP78 signaling
• cancer
• heat shock protein
• neurological disorders

• BiP
• Cancer-targeting
• GRP78
• Natural compounds
• Peptide inhibitors
• SARS-CoV-2

Promoting axonal growth is essential for repairing damaged neuronal connections and motor function in spinal cord injury (SCI). Neuroleukin (NLK) exerts axonal growth activity in vitro and in vivo, but the mechanism remains unclear. This study reveals that the 78-kDa glucose-regulated protein (GRP78) is a NLK neuronal receptor that contributes to recovery from SCI. Binding and immunoprecipitation assays indicated that NLK binds to GRP78. Pretreatment to cultured neurons with a GRP78-neutralizing antibody suppressed NLK-induced axonal growth. Blocking cell surface GRP78 inhibited neuronal NLK-induced Akt activation. Treatment with an Akt inhibitor suppressed NLK-induced axonal growth. Continuous administration of NLK into the lateral ventricle of SCI mice increased axonal density in the injured region and restored motor function, which was not observed when NLK was simultaneously administered with a GRP78-neutralizing antibody. These results indicate that GRP78 regulates the NLK-induced axonal growth activity; NLK-GRP78 signaling promotes motor function recovery in SCI, presenting as a potential therapeutic target.

• 78 kDa glucose regulated protein
• axonal growth
• neuroleukin
• recovery of motor function
• spinal cord injury

Increased endoplasmic reticulum (ER) stress is one of the earliest subcellular changes in neuro-ophthalmic diseases. In this study, we investigated the expression of key molecules in the ER stress pathways following nonarteritic anterior ischemic optic neuropathy (AION), the most common acute optic neuropathy in adults over 50, and assessed the impact of chemical chaperon 4-phenylbutyric acid (4-PBA) in vivo.

We induced AION using photochemical thrombosis in adult mice and performed histologic analyses of key molecules in the ER stress pathway in the retina and optic nerve. We also assessed the effects of daily intraperitoneal injections of 4-PBA after AION.

In the retina at baseline, there was low proapoptotic transcriptional regulator C/EBP homologous protein (CHOP) and high prosurvival chaperon glucose-regulated protein 78 (GRP78) expression in retinal ganglion cells (RGCs). One day after AION, there was significantly increased CHOP and reduced GRP78 expressions in the ganglion cell layer. In the optic nerve at baseline, there was little CHOP and high GRP78 expression. One day after AION, there was significantly increased CHOP and no change in GRP78 expression. Treatment immediately after AION using daily intraperitoneal injection of chemical chaperone 4-PBA for 19 days significantly rescued Brn3A⁺ RGCs and Olig2⁺ optic nerve oligodendrocytes.

We showed for the first time that acute AION resulted in increased ER stress and differential expression of ER stress markers CHOP and GRP78 in the retina and optic nerve. Rescue of RGCs and oligodendrocytes with 4-PBA provides support for ER stress reduction as possible treatment for AION.

• Animals
• Apoptosis/drug effects
• Chondrocytes/cytology
• Chondrocytes/drug effects
• Cigarette Smoking/adverse effects
• Extracellular Matrix/drug effects
• Extracellular Matrix/metabolism
• Intervertebral Disc/cytology
• Male
• Rats
• Rats, Sprague-Dawley
• Tobacco Smoke Pollution/adverse effects

• Ono Pharmaceutical
• Stryker Japan K.K.
• Nakashima Medical Co., Ltd.

Cerebral ischemia is a complex pathology involving a cascade of cellular mechanisms, which deregulate proteostasis and lead to neuronal death. Proteostasis refers to the equilibrium between protein synthesis, folding, transport, and protein degradation. Within the brain proteostasis plays key roles in learning and memory by controlling protein synthesis and degradation. Two important pathways are implicated in the regulation of proteostasis: the unfolded protein response (UPR) and macroautophagy (called hereafter autophagy). Both are necessary for cell survival, however, their over-activation in duration or intensity can lead to cell death. Moreover, UPR and autophagy can activate and potentiate each other to worsen the issue of cerebral ischemia. A better understanding of autophagy and ER stress will allow the development of therapeutic strategies for stroke, both at the acute phase and during recovery. This review summarizes the latest therapeutic advances implicating ER stress or autophagy in cerebral ischemia. We argue that the processes governing proteostasis should be considered together in stroke, rather than focusing either on ER stress or autophagy in isolation.

• ER stress
• autophagy
• mTOR
• proteostasis
• stroke

The purpose of this study was to determine the value of the endoplasmic reticulum (ER) stress markers glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and PERK in predicting the success of cardiopulmonary resuscitation (CPR) or post-CPR survival.

Non-traumatic out-of-hospital CA patients were included in this prospective, nested case-control study. Standard CPR and post-resuscitative care were applied. Levels of ER stress markers were measured at presentation and were investigated to determine whether they might constitute a marker predicting return of spontaneous circulation (ROSC) or sustained ROSC, and of 24-h, and 1 and 3-month survival.

Fifty-two out of 99 non-traumatic CA patients were enrolled. ROSC was determined at a level of 25%, sustained ROSC at 23%, 24-h survival at 7%, and 1- and 3-month survival at 4.6%. No difference was determined in terms of ER stress markers between patients with and without ROSC or sustained ROSC. Only PERK levels were higher in surviving patients than non-surviving subjects in terms of 24-h survival (p = 0.01). Otherwise, no stress markers differed between surviving and non-surviving patients at any survival time point.

ER stress markers are of no value in determining establishment of ROSC or sustained ROSC, success of CPR, or survival. Only PERK levels may be valuable in terms of 24-h survival.

• CHOP
• Cardiac arrest
• Cardiopulmonary resuscitation
• Endoplasmic reticulum stress
• GRP78
• PERK
• Survival

Under pathological conditions in the central nervous system (CNS), including spinal cord injury, astrocytes show detrimental effects against neurons. It is also known that astrocytes sometimes exert beneficial effects, such as neuroprotection and secretion of axonal growth factors. If beneficial effects of astrocytes after injury could be induced, dysfunction of the injured CNS may improve. However, a way of promoting beneficial functions in astrocytes has not been elucidated. In the current study, we focused on neuroleukin (NLK), which is known to have axonal growth activities in neurons. Although NLK is secreted from astrocytes, the function of NLK in astrocytes is poorly understood. We aimed to clarify the mechanism of NLK secretion in astrocytes and the functional significance of secreted NLK from astrocytes. Stimulation of cultured astrocytes with recombinant NLK significantly elevated the secretion of NLK from astrocytes. Furthermore, astrocyte conditioned medium treated with NLK increased axonal density in cultured cortical neurons. Recombinant NLK itself directly increased axonal density in cultured neurons. These results indicated that NLK secreted from astrocytes acted as an axonal growth factor and that secretion was stimulated by extracellular NLK. To elucidate a direct binding molecule of NLK on astrocytes, drug affinity responsive target stability (DARTS) analysis was performed. A 78 kDa glucose regulated protein (GRP78) was identified as a receptor for NLK, which was related to the secretion of NLK from astrocytes. When NLK was injected into the lesion site of spinal cord injured mice, axonal density in the injured region was significantly increased and hindlimb motor function improved. These results suggested that NLK-GRP78 signalling was important for the beneficial effects of astrocytes. This study strengthens the potential of astrocytes for use as therapeutic targets in CNS traumatic injury.

• 78 kDa glucose regulated protein
• astrocytes
• axonal growth
• neuroleukin
• spinal cord injury

• Apoptosis
• Cardiomyocyte
• Oxidative stress
• Propofol

• Animals
• Animals, Newborn
• Apoptosis/drug effects
• Caspases/genetics
• Cell Survival/drug effects
• Endoplasmic Reticulum Chaperone BiP
• Endoplasmic Reticulum Stress/drug effects
• Gene Expression Regulation/drug effects
• Glutathione/genetics
• Humans
• Hydrogen Peroxide/toxicity
• Membrane Potential, Mitochondrial/drug effects
• Mitochondria/drug effects
• Mitochondria/genetics
• Oxidative Stress/drug effects
• Propofol/administration & dosage
• Rats
• Reactive Oxygen Species/metabolism
• Signal Transduction/drug effects
• Superoxide Dismutase/genetics

• Amyloid aggregation
• Antibiotic
• Drug repurposing
• Neuroprotection

• 78-kDa glucose-regulated protein
• cell survival
• hypoxia
• ischemic injury
• mesenchymal stem cell
• proliferation

AIM: To investigate the role of activating transcription factor 4 (ATF4) in glucose deprivation (GD) induced colorectal cancer (CRC) drug resistance and the mechanism involved.

METHODS: Chemosensitivity and apoptosis were measured under the GD condition. Inhibition of ATF4 using short hairpin RNA in CRC cells under the GD condition and in ATF4-overexpressing CRC cells was performed to identify the role of ATF4 in the GD induced chemoresistance. Quantitative real-time RT-PCR and Western blot were used to detect the mRNA and protein expression of drug resistance gene 1 (MDR1), respectively.

RESULTS: GD protected CRC cells from drug-induced apoptosis (oxaliplatin and 5-fluorouracil) and induced the expression of ATF4, a key gene of the unfolded protein response. Depletion of ATF4 in CRC cells under the GD condition can induce apoptosis and drug re-sensitization. Similarly, inhibition of ATF4 in the ATF4-overexpressing CRC cells reintroduced therapeutic sensitivity and apoptosis. In addition, increased MDR1 expression was observed in GD-treated CRC cells.

CONCLUSION: These data indicate that GD promotes chemoresistance in CRC cells through up-regulating ATF4 expression.

• Glucose deprivation
• ATF4
• Oxaliplatin
• 5-Fluorouracil
• Chemoresistance

• ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
• Activating Transcription Factor 4/genetics
• Activating Transcription Factor 4/metabolism
• Antineoplastic Combined Chemotherapy Protocols/pharmacology
• Apoptosis/genetics
• Blotting, Western
• Cell Line, Tumor
• Cell Proliferation/drug effects
• Colorectal Neoplasms/metabolism
• Drug Resistance, Neoplasm/genetics
• Endoplasmic Reticulum Chaperone BiP
• Fluorouracil/administration & dosage
• Gene Knockdown Techniques
• Glucose/deficiency
• Glucose/metabolism
• HCT116 Cells
• Heat-Shock Proteins/genetics
• Heat-Shock Proteins/metabolism
• Humans
• Organoplatinum Compounds/administration & dosage
• Oxaliplatin
• Real-Time Polymerase Chain Reaction
• Reverse Transcriptase Polymerase Chain Reaction
• Tumor Microenvironment
• eIF-2 Kinase/genetics
• eIF-2 Kinase/metabolism

Physiological stress takes place in the endoplasmic reticulum (ER) of cells where activation and up-regulation of genes and proteins are primarily induced to enhance pro-survival mechanisms such as the unfolded protein response (UPR). A dominant protein in the UPR response is the heat shock GRP78 protein. Although GRP78 is primarily located in the ER, under certain conditions it is transported to the cell surface, where it acts as a receptor inducing pathways of cell signaling such as proliferation or apoptosis. In the prolonged chronic stress transportation of the GRP78 from the ER to the cell membrane is a major event where in addition to the presentation of the GRP78 as a receptor to various ligands, it also marks the cells that will proceed to apoptotic pathways. In the normal cell that under stress acquires cell surface GRP78 and in the tumor cell that already presents cell surface GRP78, cell surface GRP78 is an apoptotic flag. The internalization of GRP78 from the cell surface in normal cells by ligands such as peptides will enhance cell survival and alleviate cardiovascular ischemic diseases. The absence of cell surface GRP78 in the tumor cells portends proliferative and metastatic tumors. Pharmacological induction of cell surface GRP78 will induce the process of apoptosis and might be used as a therapeutic modality for cancer treatment.

• Cell surface GRP78
• Apoptosis
• Endoplasmic reticulum stress
• Tumor cells
• Cancer
• Cardiovascular ischemia
• Hypoxia

• triple negative breast cancer cells
• drug induced cell surface grp78
• apoptosis

• Animals
• Apoptosis
• Cell Line, Tumor
• Cell Membrane/metabolism
• Cell Separation
• Doxorubicin/therapeutic use
• Endoplasmic Reticulum Chaperone BiP
• Female
• Flow Cytometry
• Gene Expression Regulation, Neoplastic
• Heat-Shock Proteins/metabolism
• Humans
• Mammary Neoplasms, Experimental/metabolism
• Mice
• Signal Transduction
• Transcription Factor CHOP/metabolism
• Triple Negative Breast Neoplasms/metabolism
• Tunicamycin/therapeutic use
• Unfolded Protein Response

• Aged
• Aged, 80 and over
• Aging/genetics
• Aging/pathology
• Apoptosis/genetics
• Autopsy
• Dopaminergic Neurons/metabolism
• Dopaminergic Neurons/pathology
• Female
• Gene Expression Regulation/genetics
• Gene Regulatory Networks/genetics
• Genomics
• Humans
• Locus Coeruleus/metabolism
• Locus Coeruleus/pathology
• Male
• Middle Aged
• Nerve Degeneration/genetics
• Nerve Degeneration/pathology
• Parkinson Disease/genetics
• Parkinson Disease/pathology
• Substantia Nigra/metabolism
• Substantia Nigra/pathology

• R01 AG040311 NIA NIH HHS

• Brain
• Brain Physiology
• Cell Proliferation
• GRP78
• Kinetics
• Neurochemistry
• Pg Activation
• Protein Folding
• t-PA

Rifampicin has been proposed as a therapeutic candidate for Parkinson's disease (PD). We previously showed that rifampicin was neuroprotective in PD models in vivo and in vitro. However, the molecular mechanisms underlying are not fully elucidated. In this study, using the comprehensive proteomic analysis, we identified that the 78 kDa glucose-regulated protein (GRP78), a hallmark of the unfolded protein response (UPR), was upregulated in rifampicin-treated PC12 cells. Western blot analysis confirmed GRP78 activation. GRP78 functions cytoprotectively in stressed cells, therefore, we hypothesized that GRP78 mediated rifampicin-induced neuroprotection. Using RNA interference, we found that GRP78 gene knockdown significantly attenuated the neuroprotective effects of rifampicin. Next, we examined three UPR transducers, namely, protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol requiring kinase α (IREα) and activating transcription factor 6 (ATF 6), and how they regulated rifampicin-stimulated GRP78 expression. Our results showed that PERK, eukaryotic initiation factor 2α (eIF2α), and activating transcription factor 4 (ATF4) were activated in rifampicin-treated PC12 cells. Silencing the ATF4 gene using RNAi inhibited GRP78 stimulation. Interestingly, we did not detect significant IREα activation, X-box binding protein 1 mRNA splicing, or ATF6 cleavage up to 24 h after rifampicin treatment. Taken together, our data suggested that rifampicin induced GRP78 via the PERK-eIF2α-ATF4 pathway to protect neurons against rotenone-induced cell damage. Targeting molecules in this pathway could be a novel therapeutic approach for PD treatment.

• Activating Transcription Factor 4/metabolism
• Activating Transcription Factor 6/metabolism
• Animals
• Cell Death/drug effects
• DNA-Binding Proteins/metabolism
• Electrophoresis, Gel, Two-Dimensional
• Endoplasmic Reticulum Chaperone BiP
• Endoribonucleases/metabolism
• Eukaryotic Initiation Factor-2/metabolism
• Heat-Shock Proteins/metabolism
• Neuroprotective Agents/pharmacology
• PC12 Cells
• Rats
• Regulatory Factor X Transcription Factors
• Rifampin/pharmacology
• Rotenone/pharmacology
• Signal Transduction/drug effects
• Time Factors
• Transcription Factors/metabolism
• eIF-2 Kinase/metabolism

Parkinson disease is mainly characterized by the degeneration of dopaminergic neurons in the central nervous system, including the retina. Different interrelated molecular mechanisms underlying Parkinson disease-associated neuronal death have been put forward in the brain, including oxidative stress and mitochondrial dysfunction. Systemic injection of the proneurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to monkeys elicits the appearance of a parkinsonian syndrome, including morphological and functional impairments in the retina. However, the intracellular events leading to derangement of dopaminergic and other retinal neurons in MPTP-treated animal models have not been so far investigated. Here we have used a comparative proteomics approach to identify proteins differentially expressed in the retina of MPTP-treated monkeys. Proteins were solubilized from the neural retinas of control and MPTP-treated animals, labelled separately with two different cyanine fluorophores and run pairwise on 2D DIGE gels. Out of >700 protein spots resolved and quantified, 36 were found to exhibit statistically significant differences in their expression levels, of at least ±1.4-fold, in the parkinsonian monkey retina compared with controls. Most of these spots were excised from preparative 2D gels, trypsinized and subjected to MALDI-TOF MS and LC-MS/MS analyses. Data obtained were used for protein sequence database interrogation, and 15 different proteins were successfully identified, of which 13 were underexpressed and 2 overexpressed. These proteins were involved in key cellular functional pathways such as glycolysis and mitochondrial electron transport, neuronal protection against stress and survival, and phototransduction processes. These functional categories underscore that alterations in energy metabolism, neuroprotective mechanisms and signal transduction are involved in MPTP-induced neuronal degeneration in the retina, in similarity to mechanisms thought to underlie neuronal death in the Parkinson’s diseased brain and neurodegenerative diseases of the retina proper.