title: Inhibition of TRPC6 by protein kinase C isoforms in cultured human podocytes.
abstract: Transient receptor potential canonical-6 (TRPC6) ion channels, expressed at high levels in podocytes of the filtration barrier, are recently implicated in the pathogenesis of various forms of proteinuric kidney diseases. Indeed, inherited or acquired up-regulation of TRPC6 activities are suggested to play a role in podocytopathies. Yet, we possess limited information about the regulation of TRPC6 in human podocytes. Therefore, in this study, we aimed at defining how the protein kinase C (PKC) system, one of the key intracellular signalling pathways, regulates TRPC6 function and expression. On human differentiated podocytes, we identified the molecular expressions of both TRPC6 and several PKC isoforms. We also showed that TRPC6 channels are functional since the TRPC6 activator 1-oleoyl-2-acetyl-sn-glycerol (OAG) induced Ca(2+) -influx to the cells. By assessing the regulatory roles of the PKCs, we found that inhibitors of the endogenous activities of classical and novel PKC isoforms markedly augmented TRPC6 activities. In contrast, activation of the PKC system by phorbol 12-myristate 13-acetate (PMA) exerted inhibitory actions on TRPC6 and suppressed its expression. Importantly, PMA treatment markedly down-regulated the expression levels of PKCα, PKCβ, and PKCη reflecting their activation. Taken together, these results indicate that the PKC system exhibits a 'tonic' inhibition on TRPC6 activity in human podocytes suggesting that pathological conditions altering the expression and/or activation patterns of podocyte-expressed PKCs may influence TRPC6 activity and hence podocyte functions. Therefore, it is proposed that targeted manipulation of certain PKC isoforms might be beneficial in certain proteinuric kidney diseases with altered TRPC6 functions.
authors.affiliation: DE-MTA "Lendület" Cellular Physiology Research Group, Department of Physiology, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: Lídia
authors.initials: L
authors.lastname: Ambrus
authors.affiliation: DE-MTA "Lendület" Cellular Physiology Research Group, Department of Physiology, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: Attila
authors.identifier: http://orcid.org/0000-0003-4122-5639
authors.initials: A
authors.lastname: Oláh
authors.affiliation: Department of Physiology, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Oláh
authors.affiliation: Department of Pediatrics, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: György
authors.initials: G
authors.lastname: Balla
authors.affiliation: Renal Academic Unit, University of Bristol, Bristol, UK.
authors.forename: Moin A
authors.initials: MA
authors.lastname: Saleem
authors.affiliation: Department of Pediatrics, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: Petronella
authors.initials: P
authors.lastname: Orosz
authors.affiliation: Department of Health Systems Management and Quality Management for Health Care, Faculty of Public Health, University of Debrecen, Debrecen, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Zsuga
authors.affiliation: Department of Health Systems Management and Quality Management for Health Care, Faculty of Public Health, University of Debrecen, Debrecen, Hungary.
authors.forename: Klára
authors.initials: K
authors.lastname: Bíró
authors.affiliation: Department of Physiology, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Csernoch
authors.affiliation: DE-MTA "Lendület" Cellular Physiology Research Group, Department of Physiology, Medical Faculty, University of Debrecen, Debrecen, Hungary.|Department of Immunology, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Bíró
authors.affiliation: Department of Pediatrics, Medical Faculty, University of Debrecen, Debrecen, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Szabó
mesh_terms: D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004075:Diglycerides / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D018613:Microscopy, Confocal; D050199:Podocytes / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta / Q000378:metabolism*; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*; D000074287:TRPC6 Cation Channel; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C038237:1-oleoyl-2-acetylglycerol; C081975:protein kinase C eta; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium
keywords: human podocytes; protein kinase C isoforms; proteinuria; transient receptor potential canonical-6