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Lepa C, Hoppe S, Stöber A, Skryabin BV, Sievers LK, Heitplatz B, Ciarimboli G, Neugebauer U, Lindenmeyer MT, Cohen CD, Drexler HC, Boor P, Weide T, Pavenstädt H, George B. TrkC Is Essential for Nephron Function and Trans-Activates Igf1R Signaling. J Am Soc Nephrol 2021; 32:357-374. [PMID: 33380522 PMCID: PMC8054883 DOI: 10.1681/asn.2020040424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 11/03/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Injury to kidney podocytes often results in chronic glomerular disease and consecutive nephron malfunction. For most glomerular diseases, targeted therapies are lacking. Thus, it is important to identify novel signaling pathways contributing to glomerular disease. Neurotrophic tyrosine kinase receptor 3 (TrkC) is expressed in podocytes and the protein transmits signals to the podocyte actin cytoskeleton. METHODS Nephron-specific TrkC knockout (TrkC-KO) and nephron-specific TrkC-overexpressing (TrkC-OE) mice were generated to dissect the role of TrkC in nephron development and maintenance. RESULTS Both TrkC-KO and TrkC-OE mice exhibited enlarged glomeruli, mesangial proliferation, basement membrane thickening, albuminuria, podocyte loss, and aspects of FSGS during aging. Igf1 receptor (Igf1R)-associated gene expression was dysregulated in TrkC-KO mouse glomeruli. Phosphoproteins associated with insulin, erb-b2 receptor tyrosine kinase (Erbb), and Toll-like receptor signaling were enriched in lysates of podocytes treated with the TrkC ligand neurotrophin-3 (Nt-3). Activation of TrkC by Nt-3 resulted in phosphorylation of the Igf1R on activating tyrosine residues in podocytes. Igf1R phosphorylation was increased in TrkC-OE mouse kidneys while it was decreased in TrkC-KO kidneys. Furthermore, TrkC expression was elevated in glomerular tissue of patients with diabetic kidney disease compared with control glomerular tissue. CONCLUSIONS Our results show that TrkC is essential for maintaining glomerular integrity. Furthermore, TrkC modulates Igf-related signaling in podocytes.
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Affiliation(s)
- Carolin Lepa
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Sascha Hoppe
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Antje Stöber
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Boris V. Skryabin
- Medical Faculty, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), Westfälische-Wilhelms-University, Münster, Germany
| | | | - Barbara Heitplatz
- Gerhard-Domagk Institute for Pathology, University Hospital Münster, Münster, Germany
| | | | - Ute Neugebauer
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Maja T. Lindenmeyer
- III. Medizinische Klinik und Poliklinik, University Hospital Hamburg-Eppendorf, Germany
| | - Clemens D. Cohen
- Klinik für Nieren-, Hochdruck- und Rheumaerkrankungen, München Klinik Harlaching, Germany
| | - Hannes C.A. Drexler
- Mass Spectrometry Unit, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Peter Boor
- Institute of Pathology and Department of Nephrology, University Hospital Aachen, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany
| | - Thomas Weide
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | | | - Britta George
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
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Dlugos CP, Picciotto C, Lepa C, Krakow M, Stöber A, Eddy ML, Weide T, Jeibmann A, P Krahn M, Van Marck V, Klingauf J, Ricker A, Wedlich-Söldner R, Pavenstädt H, Klämbt C, George B. Nephrin Signaling Results in Integrin β1 Activation. J Am Soc Nephrol 2019; 30:1006-1019. [PMID: 31097607 DOI: 10.1681/asn.2018040362] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 03/18/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with certain mutations in the gene encoding the slit diaphragm protein Nephrin fail to develop functional slit diaphragms and display severe proteinuria. Many adult-onset glomerulopathies also feature alterations in Nephrin expression and function. Nephrin signals from the podocyte slit diaphragm to the Actin cytoskeleton by recruiting proteins that can interact with C3G, a guanine nucleotide exchange factor of the small GTPase Rap1. Because Rap activity affects formation of focal adhesions, we hypothesized that Nephrin transmits signals to the Integrin receptor complex, which mediates podocyte adhesion to the extracellular matrix. METHODS To investigate Nephrin's role in transmitting signals to the Integrin receptor complex, we conducted genetic studies in Drosophila nephrocytes and validated findings from Drosophila in a cultured human podocyte model. RESULTS Drosophila nephrocytes form a slit diaphragm-like filtration barrier and express the Nephrin ortholog Sticks and stones (Sns). A genetic screen identified c3g as necessary for nephrocyte function. In vivo, nephrocyte-specific gene silencing of sns or c3g compromised nephrocyte filtration and caused nephrocyte diaphragm defects. Nephrocytes with impaired Sns or C3G expression displayed an altered localization of Integrin and the Integrin-associated protein Talin. Furthermore, gene silencing of c3g partly rescued nephrocyte diaphragm defects of an sns overexpression phenotype, pointing to genetic interaction of sns and c3g in nephrocytes. We also found that activated Nephrin recruited phosphorylated C3G and resulted in activation of Integrin β1 in cultured podocytes. CONCLUSIONS Our findings suggest that Nephrin can mediate a signaling pathway that results in activation of Integrin β1 at focal adhesions, which may affect podocyte attachment to the extracellular matrix.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Christian Klämbt
- Neurobiology, Westfälische-Wilhelms University Münster, Münster, Germany
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Schilling M, Strecker J, Müller M, Stöber A, Ringelstein E, Kiefer R. Untersuchung der Migration hämatogener Makrophagen in das Gehirn nach ischämischem Schlaganfall in Abhängigkeit von der Bestrahlungsintensität bei der Produktion knochenmarkchimärer Mäuse. Akt Neurol 2005. [DOI: 10.1055/s-2005-919702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Strecker J, Schilling M, Müller M, Stöber A, Ringelstein E, Kiefer R. Der Einfluss von Chemokinen auf den Austausch perivaskulärer und meningealer Makrophagen des Gehirns: eine Studie an genetisch defizienten knochenmarkchimären Mäusen. Akt Neurol 2005. [DOI: 10.1055/s-2005-919703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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