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Honda K, Kajino A, Tsutsumi T. Comparative genomic profiling of SLC26A4-expressing cells in the inner ear and other organs. PLoS One 2025; 20:e0318972. [PMID: 39932986 PMCID: PMC11813142 DOI: 10.1371/journal.pone.0318972] [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: 11/29/2024] [Accepted: 01/25/2025] [Indexed: 02/13/2025] Open
Abstract
Pendred syndrome and autosomal recessive non-syndromic hearing loss, type 4 (DFNB4), are associated with mutations in SLC26A4 that encodes the anion transporter SLC26A4 (pendrin). SLC26A4 is expressed in mitochondria-rich cells of the endolymphatic sac, spindle and root cells in the cochlear lateral wall, transitional cells in the vestibular organs, follicular cells in the thyroid, and type B intercalated cells in the kidney. This study aimed to assess the gene profiles of murine Slc26a4-expressing cells to better understand the regulatory mechanisms and functions of SLC26A4. Publicly available murine single-cell or single-nucleus RNA-sequencing (RNA-seq) datasets from the endolymphatic sac, cochlear lateral wall, utricle, kidney, airway, epididymis, and salivary glands were collected. After quality control, principal component analysis and clustering, distinct cell populations were identified, and differentially expressed genes (DEGs) were analyzed. The datasets were integrated for comparison across multiple tissues and organs. The results revealed no shared genetic profile among inner ear Slc26a4-expressing cells, with Slc26a4 being the only shared DEG, suggesting that regulatory genes may include low expression transcripts, splicing variants, or long non-coding RNAs undetectable by single-cell analysis. Comparative analysis within the ionocyte family identified distinct DEGs such as Insrr and Hmx2 in Slc26a4-expressing cells from the endolymphatic sac and kidneys, potentially significant in ion homeostasis and SLC26A4 regulation. This study highlights the specificity and complexity of SLC26A4 expression and highlights the challenges and limitations of single-cell analysis. Future research should address regulatory elements such as low-expression genes, splicing variants, and non-coding RNAs to enhance our understanding of SLC26A4 regulation across various cellular contexts.
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Affiliation(s)
- Keiji Honda
- Department of Otorhinolaryngology, Institute of Science Tokyo, Tokyo, Japan
| | - Akimasa Kajino
- Department of Otorhinolaryngology, Institute of Science Tokyo, Tokyo, Japan
| | - Takeshi Tsutsumi
- Department of Otorhinolaryngology, Institute of Science Tokyo, Tokyo, Japan
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Tahaei E, Pham TD, Al-Qusairi L, Grimm R, Wall SM, Welling PA. Pendrin regulation is prioritized by anion in high-potassium diets. Am J Physiol Renal Physiol 2023; 324:F256-F266. [PMID: 36656986 PMCID: PMC9942896 DOI: 10.1152/ajprenal.00128.2022] [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: 05/03/2022] [Revised: 12/21/2022] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
The Cl-/[Formula: see text] exchanger pendrin in the kidney maintains acid-base balance and intravascular volume. Pendrin is upregulated in models associated with high circulating aldosterone concentration, such as dietary NaCl restriction or an aldosterone infusion. However, it has not been established if pendrin is similarly regulated by aldosterone with a high-K+ diet because the effects of accompanying anions have not been considered. Here, we explored how pendrin is modulated by different dietary potassium salts. Wild-type (WT) and aldosterone synthase (AS) knockout (KO) mice were randomized to control, high-KHCO3, or high-KCl diets. Dietary KCl and KHCO3 loading increased aldosterone in WT mice to the same extent but had opposite effects on pendrin abundance. KHCO3 loading increased pendrin protein and transcript abundance. Conversely, high-KCl diet feeding caused pendrin to decrease within 8 h of switching from the high-KHCO3 diet, coincident with an increase in plasma Cl- and a decrease in [Formula: see text]. In contrast, switching the high-KCl diet to the high-KHCO3 diet caused pendrin to increase in WT mice. Experiments in AS KO mice revealed that aldosterone is necessary to optimally upregulate pendrin protein in response to the high-KHCO3 diet but not to increase pendrin mRNA. We conclude that pendrin is differentially regulated by different dietary potassium salts and that its regulation is prioritized by the dietary anion, providing a mechanism to prevent metabolic alkalosis with high-K+ base diets and safeguard against hyperchloremic acidosis with consumption of high-KCl diets.NEW & NOTEWORTHY Regulation of the Cl-/[Formula: see text] exchanger pendrin has been suggested to explain the aldosterone paradox. A high-K+ diet has been proposed to downregulate a pendrin-mediated K+-sparing NaCl reabsorption pathway to maximize urinary K+ excretion. Here, we challenged the hypothesis, revealing that the accompanying anion, not K+, drives pendrin expression. Pendrin is downregulated with a high-KCl diet, preventing acidosis, and upregulated with an alkaline-rich high-K+ diet, preventing metabolic alkalosis. Pendrin regulation is prioritized for acid-base balance.
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Affiliation(s)
- Ebrahim Tahaei
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Truyen D Pham
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Lama Al-Qusairi
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Rick Grimm
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Paul A Welling
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
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Singh S, Sharma R, Kumari M, Tiwari S. Insulin receptors in the kidneys in health and disease. World J Nephrol 2019; 8:11-22. [PMID: 30705868 PMCID: PMC6354081 DOI: 10.5527/wjn.v8.i1.11] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/15/2018] [Accepted: 12/10/2018] [Indexed: 02/06/2023] Open
Abstract
Insulin is an important hormone that affects various metabolic processes, including kidney function. Impairment in insulin’s action leads to insulin resistance in the target tissue. Besides defects in post-receptor insulin signaling, impairment at the receptor level could significantly affect insulin sensitivity of the target tissue. The kidney is a known target of insulin; however, whether the kidney develops “insulin resistance” is debatable. Regulation of the insulin receptor (IR) expression and its function is very well studied in major metabolic tissues like liver, skeletal muscles, and adipose tissue. The physiological relevance of IRs in the kidney has recently begun to be clarified. The credit goes to studies that showed a wide distribution of IR throughout the nephron segments and their reduced expression in the insulin resistance state. Moreover, altered renal and systemic metabolism observed in mice with targeted deletion of the IR from various epithelial cells of the kidney has strengthened this proposition. In this review, we recapitulate the crucial findings from literature that have expanded our knowledge regarding the significance of the renal IR in normal- and insulin-resistance states.
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Affiliation(s)
- Sarojini Singh
- Department of Molecular Medicine and Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
| | - Rajni Sharma
- Department of Molecular Medicine and Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
| | - Manju Kumari
- Department of Molecular Medicine and Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
| | - Swasti Tiwari
- Department of Molecular Medicine and Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
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Deyev IE, Shayahmetova DM, Zhenilo SV, Radionov NV, Petrenko AG. Profile of Gene Expression in the Kidneys of Mice with the insrr Gene Knockout. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2018. [DOI: 10.1134/s1068162018020115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Alkaline pH induces IRR-mediated phosphorylation of IRS-1 and actin cytoskeleton remodeling in a pancreatic beta cell line. Biochimie 2017; 138:62-69. [PMID: 28438671 DOI: 10.1016/j.biochi.2017.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/22/2017] [Accepted: 04/03/2017] [Indexed: 11/22/2022]
Abstract
Secretion of mildly alkaline (pH 8.0-8.5) juice to intestines is one of the key functions of the pancreas. Recent reports indicate that the pancreatic duct system containing the alkaline juice may adjoin the endocrine cells of pancreatic islets. We have previously identified the insulin receptor-related receptor (IRR) that is expressed in islets as a sensor of mildly alkaline extracellular media. In this study, we show that those islet cells that are in contact with the excretory ducts are also IRR-expressing cells. We further analyzed the effects of alkaline media on pancreatic beta cell line MIN6. Activation of endogenous IRR but not of the insulin receptor was detected that could be inhibited with linsitinib. The IRR autophosphorylation correlated with pH-dependent linsitinib-sensitive activation of insulin receptor substrate 1 (IRS-1), the primary adaptor in the insulin signaling pathway. However, in contrast with insulin stimulation, no protein kinase B (Akt/PKB) phosphorylation was detected as a result of alkali treatment. We observed overexpression of several early response genes (EGR2, IER2, FOSB, EGR1 and NPAS4) upon alkali treatment of MIN6 cells but those were IRR-independent. The alkaline medium but not insulin also triggered actin cytoskeleton remodeling that was blocked by pre-incubation with linsitinib. We propose that the activation of IRR by alkali might be part of a local loop of signaling between the exocrine and endocrine parts of the pancreas where alkalinization of the juice facilitate insulin release that increases the volume of secreted juice to control its pH and bicabonate content.
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Six2creFrs2α knockout mice are a novel model of renal cystogenesis. Sci Rep 2016; 6:36736. [PMID: 27853247 PMCID: PMC5113122 DOI: 10.1038/srep36736] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/14/2016] [Indexed: 01/06/2023] Open
Abstract
Six2cre-mediated deletion of Frs2α (Six2creFrs2αKO), a major fibroblast growth factor receptor (Fgfr) docking protein in mouse nephron progenitors results in perinatal renal hypoplasia; however, postnatal Six2creFrs2αKO kidneys develop cysts. We sought to determine the pathogenesis of Six2creFrs2αKO cyst formation. We performed histological assays, Western blots, and quantitative PCR (qPCR). While embryonic day (E) 18.5 Six2Frs2αKO kidneys were hypoplastic and not cystic, postnatal day (P) 7 mutants had proximal tubular-derived cysts that nearly replaced the renal parenchyma by P21. Mutants had high proximal tubular proliferation rates and interstitial fibrosis, similar to known polycystic kidney disease (PKD) models. Six2creFrs2αKO kidneys also had upregulation of Wnt/βcatenin signaling, macrophage infiltration and chemokine production (e.g. ectopic Ccl2 in non-dilated proximal tubules), and augmented hedgehog signaling, features also seen in other PKD models. We saw increased Gli1 (hedgehog readout) in postnatal Six2creFrs2αKO interstitium and ectopic sonic hedgehog (Shh) in subsets of non-dilated P7 mutant proximal tubules (likely driving the stromal Gli expression). As ectopic tubular Shh and Ccl2 expression is seen after acute kidney injury (AKI), we interrogated another bone fide AKI marker, Kim1 and noted ectopic expression in P7 non-dilated proximal tubules. These observations suggest that aberrantly activated “AKI” pathways may drive pathogenesis in PKD.
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Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
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Petrenko AG, Zozulya SA, Deyev IE, Eladari D. Insulin receptor-related receptor as an extracellular pH sensor involved in the regulation of acid–base balance. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2170-5. [DOI: 10.1016/j.bbapap.2012.11.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/16/2012] [Accepted: 11/19/2012] [Indexed: 12/25/2022]
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Li L, Garikepati RM, Tsukerman S, Kohan D, Wade JB, Tiwari S, Ecelbarger CM. Reduced ENaC activity and blood pressure in mice with genetic knockout of the insulin receptor in the renal collecting duct. Am J Physiol Renal Physiol 2012. [PMID: 23195676 DOI: 10.1152/ajprenal.00161.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
To elucidate the role of the insulin receptor (IR) in collecting duct (CD), we bred mice with IR selectively deleted from CD principal cells using an aquaporin-2 promoter to drive Cre-recombinase expression. Young, adult male knockout (KO) mice had altered plasma and electrolyte homeostasis under high- (HS) and low-sodium (LS) diets, relative to wild-type (WT) littermates. One week of LS feeding led to a significant reduction in urine potassium (K(+)) and sodium (Na(+)) excretion in KO, and a reduction in the ratio of Na(+) to chloride (Cl(-)) in plasma, relative to WT. HS diet (1 wk) increased plasma K(+) and reduced urine Na(+) to Cl(-) ratio in the KO. Furthermore, KO mice had a significantly (P = 0.025) blunted natriuretic response to benzamil, an epithelial sodium channel (ENaC) antagonist. Western blotting of cortex homogenates revealed modestly, but significantly (∼15%), lower band density for the β-subunit of ENaC in the KO vs. WT mice, with no differences for the α- or γ-subunits. Moreover, blood pressure (BP), measured by radiotelemetry, was significantly lower in KO vs. WT mice under basal conditions (mmHg): 112 ± 5 (WT), 104 ± 2 (KO), P = 0.023. Chronic insulin infusion reduced heart rate in the WT, but not in the KO, and modestly reduced BP in the WT only. Overall, these results support a fundamental role for insulin through its classic receptor in the modulation of electrolyte homeostasis and BP.
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Affiliation(s)
- Lijun Li
- Department of Medicine, Georgetown University, Washington, DC 20007, USA
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11
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Brown D, Wagner CA. Molecular mechanisms of acid-base sensing by the kidney. J Am Soc Nephrol 2012; 23:774-80. [PMID: 22362904 DOI: 10.1681/asn.2012010029] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A major function of the kidney is to collaborate with the respiratory system to maintain systemic acid-base status within limits compatible with normal cell and organ function. It achieves this by regulating the excretion and recovery of bicarbonate (mainly in the proximal tubule) and the secretion of buffered protons (mainly in the distal tubule and collecting duct). How proximal tubular cells and distal professional proton transporting (intercalated) cells sense and respond to changes in pH, bicarbonate, and CO(2) status is a question that has intrigued many generations of renal physiologists. Over the past few years, however, some candidate molecular pH sensors have been identified, including acid/alkali-sensing receptors (GPR4, InsR-RR), kinases (Pyk2, ErbB1/2), pH-sensitive ion channels (ASICs, TASK, ROMK), and the bicarbonate-stimulated adenylyl cyclase (sAC). Some acid-sensing mechanisms in other tissues, such as CAII-PDK2L1 in taste buds, might also have similar roles to play in the kidney. Finally, the function of a variety of additional membrane channels and transporters is altered by pH variations both within and outside the cell, and the expression of several metabolic enzymes are altered by acid-base status in parts of the nephron. Thus, it is possible that a master pH sensor will never be identified. Rather, the kidney seems equipped with a battery of molecules that scan the epithelial cell environment to mount a coordinated physiologic response that maintains acid-base homeostasis. This review collates current knowledge on renal acid-base sensing in the context of a whole organ sensing and response process.
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Affiliation(s)
- Dennis Brown
- MGH Center for Systems Biology, Program in Membrane Biology, Boston, MA, USA.
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12
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Deyev IE, Sohet F, Vassilenko KP, Serova OV, Popova NV, Zozulya SA, Burova EB, Houillier P, Rzhevsky DI, Berchatova AA, Murashev AN, Chugunov AO, Efremov RG, Nikol'sky NN, Bertelli E, Eladari D, Petrenko AG. Insulin receptor-related receptor as an extracellular alkali sensor. Cell Metab 2011; 13:679-89. [PMID: 21641549 PMCID: PMC3119365 DOI: 10.1016/j.cmet.2011.03.022] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 12/18/2010] [Accepted: 03/23/2011] [Indexed: 11/29/2022]
Abstract
The insulin receptor-related receptor (IRR), an orphan receptor tyrosine kinase of the insulin receptor family, can be activated by alkaline media both in vitro and in vivo at pH >7.9. The alkali-sensing property of IRR is conserved in frog, mouse, and human. IRR activation is specific, dose-dependent and quickly reversible and demonstrates positive cooperativity. It also triggers receptor conformational changes and elicits intracellular signaling. The pH sensitivity of IRR is primarily defined by its L1F extracellular domains. IRR is predominantly expressed in organs that come in contact with mildly alkaline media. In particular, IRR is expressed in the cell subsets of the kidney that secrete bicarbonate into urine. Disruption of IRR in mice impairs the renal response to alkali loading attested by development of metabolic alkalosis and decreased urinary bicarbonate excretion in response to this challenge. We therefore postulate that IRR is an alkali sensor that functions in the kidney to manage metabolic bicarbonate excess.
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Affiliation(s)
- Igor E Deyev
- Laboratory of Receptor Cell Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
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Tiwari S, Riazi S, Ecelbarger CA. Insulin's impact on renal sodium transport and blood pressure in health, obesity, and diabetes. Am J Physiol Renal Physiol 2007; 293:F974-84. [PMID: 17686957 DOI: 10.1152/ajprenal.00149.2007] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Insulin has been shown to have antinatriuretic actions in humans and animal models. Moreover, endogenous hyperinsulinemia and insulin infusion have been correlated to increased blood pressure in some models. In this review, we present the current state of understanding with regard to the regulation of the major renal sodium transporters by insulin in the kidney. Several groups, using primarily cell culture, have demonstrated that insulin can directly increase activity of the epithelial sodium channel, the sodium-phosphate cotransporter, the sodium-hydrogen exchanger type III, and Na-K-ATPase. We and others have demonstrated alterations in the expression at the protein level of many of these same proteins with insulin infusion or in hyperinsulinemic models. We also discuss how this regulation is perturbed in type I and type II diabetes mellitus. Finally, we discuss a potential role for regulation of insulin receptor signaling in the kidney in contributing to sodium balance and blood pressure.
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Affiliation(s)
- Swasti Tiwari
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, District of Columbia 20007, USA
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14
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Deev IE, Vasilenko KP, Kurmangaliev EZ, Serova OV, Popova NV, Galagan YS, Burova EB, Zozulya SA, Nikol'skii NN, Petrenko AG. Effect of changes in ambient pH on phosphorylation of cellular proteins. DOKL BIOCHEM BIOPHYS 2006; 408:184-7. [PMID: 16913425 DOI: 10.1134/s1607672906030203] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- I E Deev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow 117997, Russia
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Poladia DP, Kish K, Kutay B, Hains D, Kegg H, Zhao H, Bates CM. Role of fibroblast growth factor receptors 1 and 2 in the metanephric mesenchyme. Dev Biol 2006; 291:325-39. [PMID: 16442091 DOI: 10.1016/j.ydbio.2005.12.034] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 11/21/2005] [Accepted: 12/16/2005] [Indexed: 10/25/2022]
Abstract
To determine the importance of fibroblast growth factor receptors (fgfrs) 1 and 2 in the metanephric mesenchyme, we generated conditional knockout mice (fgfr(Mes-/-)). Fgfr1(Mes-/-) and fgfr2(Mes-/-) mice develop normal-appearing kidneys. Deletion of both receptors (fgfr1/2(Mes-/-)) results in renal aplasia. Fgfr1/2(Mes-/-) mice develop a ureteric bud (and occasionally an ectopic bud) that does not elongate or branch, and the mice do not develop an obvious metanephric mesenchyme. By in situ hybridization, regions of mutant mesenchyme near the ureteric bud(s) express Eya1 and Six1, but not Six2, Sall1, or Pax2, while the ureteric bud expresses Ret and Pax2 normally. Abnormally high rates of apoptosis and relatively low rates of proliferation are present in mutant mesenchyme dorsal to the mutant ureteric bud at embryonic day (E) 10.5, while mutant ureteric bud tissues undergo high rates of apoptosis by E11.5. Thus, fgfr1 and fgfr2 together are critical for normal formation of metanephric mesenchyme. While the ureteric bud(s) initiates, it does not elongate or branch infgfr1/2(Mes-/-) mice. In metanephric mesenchymal rudiments, fgfr1 and fgfr2 appear to function downstream of Eya1 and Six1, but upstream of Six2, Sall1, and Pax2. Finally, this is the first example of renal aplasia in a conditional knockout model.
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Affiliation(s)
- Deepali Pitre Poladia
- Center for Cell and Vascular Biology, Columbus Children's Research Institute, 700 Children's Drive, Columbus, OH 43205, USA
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16
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Dissen GA, Garcia-Rudaz C, Tapia V, Parada LF, Hsu SYT, Ojeda SR. Expression of the insulin receptor-related receptor is induced by the preovulatory surge of luteinizing hormone in thecal-interstitial cells of the rat ovary. Endocrinology 2006; 147:155-65. [PMID: 16195402 DOI: 10.1210/en.2005-0386] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The insulin receptor-related receptor (IRR) is a member of the insulin receptor family that, on its own, recognizes neither insulin nor any of the identified insulin-related peptides. In both the nervous system and peripheral tissues, IRR mRNA is detected in cells that also express trkA, the nerve growth factor tyrosine kinase receptor. In the ovary, the trkA gene is transiently activated in thecal-interstitial cells of large antral follicles at the time of the preovulatory surge of gonadotropins. The present study shows that the IRR gene is expressed in the same ovarian compartment, that IRR mRNA content increases strikingly in these cells in the afternoon of the first proestrus, and that--as in the case of trkA mRNA--the increase is caused by gonadotropins. The IRR mRNA species primarily affected is that encoding the full-length receptor; its increased abundance was accompanied by a corresponding change in IRR protein content. An extensive molecular search using several approaches, including the screening of cDNA libraries and PCR amplification with degenerate primers, did not yield an IRR ligand. Phylogenetic analysis of 20 insulin-related sequences and 15 relaxin family peptides from selected vertebrates indicated that the mammalian genome is unlikely to contain an additional ligand expressed from a distinct gene that is closely related to the insulin family. Although the functional nature of the relationship between IRR and trkA receptors is unknown, the remarkable temporal and spatial specificities of their coordinated expression in the ovary before ovulation suggests that they target a functionally related set of downstream events associated with the ovulatory process.
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Affiliation(s)
- Gregory A Dissen
- Division of Neuroscience, Oregon Regional Primate Research Center, 505 N.W. 185th Avenue, Beaverton, Oregon 97006-3448, USA.
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Zhao H, Kegg H, Grady S, Truong HT, Robinson ML, Baum M, Bates CM. Role of fibroblast growth factor receptors 1 and 2 in the ureteric bud. Dev Biol 2005; 276:403-15. [PMID: 15581874 PMCID: PMC4131686 DOI: 10.1016/j.ydbio.2004.09.002] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 08/20/2004] [Accepted: 09/01/2004] [Indexed: 10/26/2022]
Abstract
Fibroblast growth receptors (FGFRs) consist of four signaling family members. Mice with deletions of fgfr1 or fgfr2 are embryonic lethal prior to the onset of kidney development. To determine roles of FGFR1 and FGFR2 in the ureteric bud, we used a conditional targeting approach. First, we generated transgenic mice using the Hoxb7 promoter to drive cre recombinase and green fluorescent protein expression throughout ureteric bud tissue. We crossed Hoxb7creEGFP mice with mice carrying lox-p sites flanking critical regions of fgfr1 and/or fgfr2. Absence of fgfr1 from the ureteric bud (fgfr1(UB-/-)) results in no apparent renal abnormalities. In contrast, fgfr2(UB-/-) mice have very aberrant ureteric bud branching, thin ureteric bud stalks, and fewer ureteric bud tips. Fgfr2(UB-/-) ureteric bud tips also demonstrate inappropriate regions of apoptosis and reduced proliferation. The nephrogenic mesenchymal lineage in fgfr2(UB-/-) mice develops normal-appearing glomeruli and tubules, and only slightly fewer nephrons than controls. In contrast, fgfr2(UB-/-) kidneys have abnormally thickened subcapsular cortical stromal mesenchyme. Ultimately, fgfr2(UB-/-) adult kidneys are small and abnormally shaped or are hydronephrotic. Finally, there are no additional abnormalities in the fgfr1/2(UB-/-) kidneys versus the fgfr2(UB-/-) kidneys. In conclusion, FGFR2, but not FGFR1, appears crucial for ureteric bud branching morphogenesis and stromal mesenchyme patterning.
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Affiliation(s)
- Haotian Zhao
- Center for Human and Molecular Genetics, Columbus Children’s Research Institute, Columbus, OH 43205, United States
| | - Heather Kegg
- Center for Human and Molecular Genetics, Columbus Children’s Research Institute, Columbus, OH 43205, United States
| | - Sandy Grady
- Center for Human and Molecular Genetics, Columbus Children’s Research Institute, Columbus, OH 43205, United States
| | - Hoang-Trang Truong
- Department of Pediatrics, Division of Nephrology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75235, United States
| | - Michael L. Robinson
- Center for Human and Molecular Genetics, Columbus Children’s Research Institute, Columbus, OH 43205, United States
| | - Michel Baum
- Department of Pediatrics, Division of Nephrology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75235, United States
| | - Carlton M. Bates
- Center for Human and Molecular Genetics, Columbus Children’s Research Institute, Columbus, OH 43205, United States
- Department of Pediatrics, Division of Nephrology, College of Medicine and Public Health, The Ohio State University, Columbus, OH 43210, United States
- Corresponding author. Center for Human and Molecular Genetics, Columbus Children’s Research Institute, 700 Children’s Drive Columbus, Ohio 43205. Fax: +1 614 722 2817. (C.M. Bates)
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Abstract
Targeted gene mutations have established distinct, yet overlapping, developmental roles for receptors of the insulin/IGF family. IGF-I receptor mediates IGF-I and IGF-II action on prenatal growth and IGF-I action on postnatal growth. Insulin receptor mediates prenatal growth in response to IGF-II and postnatal metabolism in response to insulin. In rodents, unlike humans, insulin does not participate in embryonic growth until late gestation. The ability of the insulin receptor to act as a bona fide IGF-II-dependent growth promoter is underscored by its rescue of double knockout Igf1r/Igf2r mice. Thus, IGF-II is a true bifunctional ligand that is able to stimulate both insulin and IGF-I receptor signaling, although with different potencies. In contrast, the IGF-II/cation-independent mannose-6-phosphate receptor regulates IGF-II clearance. The growth retardation of mice lacking IGF-I and/or insulin receptors is due to reduced cell number, resulting from decreased proliferation. Evidence from genetically engineered mice does not support the view that insulin and IGF receptors promote cellular differentiation in vivo or that they are required for early embryonic development. The phenotypes of insulin receptor gene mutations in humans and in mice indicate important differences between the developmental roles of insulin and its receptor in the two species.
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Affiliation(s)
- J Nakae
- Naomi Berrie Diabetes Center, Department of Medicine, College of Physicians & Surgeons of Columbia University, New York, New York 10032, USA
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19
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Kitamura T, Kido Y, Nef S, Merenmies J, Parada LF, Accili D. Preserved pancreatic beta-cell development and function in mice lacking the insulin receptor-related receptor. Mol Cell Biol 2001; 21:5624-30. [PMID: 11463843 PMCID: PMC87283 DOI: 10.1128/mcb.21.16.5624-5630.2001] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Receptors of the insulin/insulinlike growth factor (IGF) family have been implicated in the regulation of pancreatic beta-cell growth and insulin secretion. The insulin receptor-related receptor (IRR) is an orphan receptor of the insulin receptor gene (Ir) subfamily. It is expressed at considerably higher levels in beta cells than either insulin or IGF-1 receptors, and it has been shown to engage in heterodimer formation with insulin or IGF-1 receptors. To address whether IRR plays a physiologic role in beta-cell development and regulation of insulin secretion, we have characterized mice lacking IRR and generated a combined knockout of Ir and Irr. We report that islet morphology, beta-cell mass, and secretory function are not affected in IRR-deficient mice. Moreover, lack of IRR does not impair compensatory beta-cell hyperplasia in insulin-resistant Ir(+/-) mice, nor does it affect beta-cell development and function in Ir(-/-) mice. We conclude that glucose-stimulated insulin secretion and embryonic beta-cell development occur normally in mice lacking Irr.
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Affiliation(s)
- T Kitamura
- Naomi Berrie Diabetes Center and Department of Medicine, College of Physicians & Surgeons of Columbia University, New York, New York 10032, USA
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20
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Ma L, Merenmies J, Parada LF. Molecular characterization of the TrkA/NGF receptor minimal enhancer reveals regulation by multiple cis elements to drive embryonic neuron expression. Development 2000; 127:3777-88. [PMID: 10934022 DOI: 10.1242/dev.127.17.3777] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Neural development relies on stringent regulation of key genes that mediate specialized function. TrkA is primarily expressed in neural crest-derived sensory and sympathetic neurons where it transmits critical survival information. We have identified a 457 base pair sequence upstream of the murine first TrkA coding exon that is conserved in human and in chick, and is sufficient for expression in the correct cells with appropriate timing. Mutation analysis of consensus transcription factor binding domains within the minimal enhancer reveals a complex positive regulation that includes sites required for global expression and sites that are specifically required for DRG, trigeminal or sympathetic expression. These results provide a foundation for identification of the transcriptional machinery that specifies neurotrophin receptor expression.
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Affiliation(s)
- L Ma
- Center for Developmental Biology, UT Southwestern Medical Center, Dallas, TX 75390-9133, USA
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21
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Abstract
N-myc is a transcription factor expressed in the developing metanephric kidney and other organs. In mice, complete disruption of the N-myc gene results in fetal death on the first day of renal organogenesis. In addition to the null N-myc allele, others have generated a hypomorphic N-myc allele. In this study, combinations of these mutant genes were used to demonstrate that reduction in N-myc protein levels correlate with fewer developing glomeruli and collecting ducts in embryonic kidney explants. Histological sections revealed that the mutant kidneys were hypoplastic with normal developing structures. The data indicate that the hypoplasia is due to a reduction in proliferation rather than an increase in apoptosis. Thus, N-myc loss causes a decrease in numbers of ureteric bud tips and developing glomeruli in explants and hypoplastic kidneys in vivo, in a dose-dependent manner.
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Affiliation(s)
- C M Bates
- Children's Research Institute, Children's Hospital, Columbus, Ohio, 43205, USA
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