TRPC6 G757D Loss-of-Function Mutation Associates with FSGS : Journal of the American Society of Nephrology (original) (raw)

Basic Research

Riehle, Marc*; Büscher, Anja K.†; Gohlke, Björn-Oliver‡,§; Kaßmann, Mario‖; Kolatsi-Joannou, Maria¶; Bräsen, Jan H.**; Nagel, Mato††; Becker, Jan U.‡‡; Winyard, Paul¶; Hoyer, Peter F.†; Preissner, Robert‡,§; Krautwurst, Dietmar§§; Gollasch, Maik‖; Weber, Stefanie†; Harteneck, Christian*

*Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany;

†Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany;

‡German Cancer Consortium, Heidelberg, Germany;

‖Nephrology/Intensive Care, Experimental and Clinical Research Center and Max Delbrück Center for Molecular Medicine, Charité University Medicine Berlin, Berlin, Germany;

§Charité University Medicine Berlin, Structural Bioinformatics Group, Institute of Physiology and Experimental Clinical Research Center, Berlin, Germany;

¶Nephro-Urology Unit, University College London Institute of Child Health, London, United Kingdom;

**Institute of Pathology, University Hospital of Hannover, Hannover, Germany;

††Center of Nephrology and Metabolism, Weisswasser, Germany;

‡‡Institute of Pathology, University Hospital of Cologne, Cologne, Germany; and

§§Deutsche Forschungsanstalt für Lebensmittelchemie, Molekulare Zellphysiologie und Chemorezeption, Freising, Germany

Correspondence: Dr. Stefanie Weber, Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Hufelandstrasse 55, Essen 45147, Germany, or Dr. Christian Harteneck, Institute of Pharmacology and Toxicology, Eberhard-Karls-Universität, Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany. Email: [email protected] or [email protected]

Abstract

FSGS is a CKD with heavy proteinuria that eventually progresses to ESRD. Hereditary forms of FSGS have been linked to mutations in the transient receptor potential cation channel, subfamily C, member 6 (TRPC6) gene encoding a nonselective cation channel. Most of these TRPC6 mutations cause a gain-of-function phenotype, leading to calcium–triggered podocyte cell death, but the underlying molecular mechanisms are unclear. We studied the molecular effect of disease-related mutations using tridimensional in silico modeling of tetrameric TRPC6. Our results indicated that G757 is localized in a domain forming a TRPC6-TRPC6 interface and predicted that the amino acid exchange G757D causes local steric hindrance and disruption of the channel complex. Notably, functional characterization of model interface domain mutants suggested a loss-of-function phenotype. We then characterized 19 human FSGS–related TRPC6 mutations, the majority of which caused gain-of-function mutations. However, five mutations (N125S, L395A, G757D, L780P, and R895L) caused a loss-of-function phenotype. Coexpression of wild-type TRPC6 and TRPC6 G757D, mimicking heterozygosity observed in patients, revealed a dominant negative effect of TRPC6 G757D. Our comprehensive analysis of human disease–causing TRPC6 mutations reveals loss of TRPC6 function as an additional concept of hereditary FSGS and provides molecular insights into the mechanism responsible for the loss-of-function phenotype of TRPC6 G757D in humans.