title: Sildenafil Prevents Podocyte InjuryviaPPAR-γ-Mediated TRPC6 Inhibition.
abstract: Transient receptor potential channel C6 (TRPC6) gain-of-function mutations and increased TRPC6 expression in podocytes induce glomerular injury and proteinuria. Sildenafil reduces TRPC6 expression and activity in nonrenal cell types, although the mechanism is unknown. Peroxisome proliferator-activated receptorγ(PPAR-γ) is a downstream target of sildenafil in the cyclic guanosine monophosphate (cGMP)-activated protein kinase G (PKG) axis. PPAR-γagonists, like pioglitazone, appear antiproteinuric. We hypothesized that sildenafil inhibits TRPC6 expression in podocytes through PPAR-γ-dependent mechanisms, thereby counteracting podocyte injury and proteinuria. Treatment with sildenafil, the cGMP derivative 8-bromoguanosine 3',5'-cyclic monophosphate sodium salt (8-Br-cGMP), or pioglitazone dose-dependently downregulated podocyte injury-induced TRPC6 expressionin vitroKnockdown or application of antagonists of PKG or PPAR-γenhanced TRPC6 expression in podocytes and counteracted effects of sildenafil and 8-Br-cGMP. We observed similar effects on TRPC6 promoter activity and TRPC6-dependent calcium influx. Chromatin immunoprecipitation showed PPAR-γbinding to the TRPC6 promoter. Sildenafil or pioglitazone treatment prevented proteinuria and the increased TRPC6 expression in rats with adriamycin-induced nephropathy and mice with hyperglycemia-induced renal injury. Rats receiving PPAR-γantagonists displayed proteinuria and increased podocyte TRPC6 expression, as did podocyte-specific PPAR-γknockout mice, which were more sensitive to adriamycin and not protected by sildenafil. Thus, sildenafil ameliorates podocyte injury and prevents proteinuria through cGMP- and PKG-dependent binding of PPAR-γto the TRPC6 promoter, which inhibits TRPC6 promoter activity, expression, and activity. Because sildenafil is approved for clinical use, our results suggest that additional clinical study of its antiproteinuric effect in glomerular disease is warranted.
authors.affiliation: Departments of Nephrology.
authors.forename: Ramon
authors.initials: R
authors.lastname: Sonneveld
authors.affiliation: Physiology, and.
authors.forename: Joost G
authors.initials: JG
authors.lastname: Hoenderop
authors.affiliation: Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Isidori
authors.affiliation: Paris Cardiovascular Centre, Institut National de la Santé et de la Recherche Médicale, Paris, France.|Sorbonne Paris Cité, Université Paris Descartes, Paris, France; and.
authors.forename: Carole
authors.initials: C
authors.lastname: Henique
authors.affiliation: Pathology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Henry B
authors.initials: HB
authors.lastname: Dijkman
authors.affiliation: Departments of Nephrology.
authors.forename: Jo H
authors.initials: JH
authors.lastname: Berden
authors.affiliation: Paris Cardiovascular Centre, Institut National de la Santé et de la Recherche Médicale, Paris, France.|Sorbonne Paris Cité, Université Paris Descartes, Paris, France; and.|Service de Néphrologie, Hôpital Européen Georges Pompidou, Paris, France.
authors.forename: Pierre-Louis
authors.initials: PL
authors.lastname: Tharaux
authors.affiliation: Departments of Nephrology.
authors.forename: Johan
authors.initials: J
authors.lastname: van der Vlag
authors.affiliation: Departments of Nephrology, Tom.Nijenhuis@Radboudumc.nl.
authors.forename: Tom
authors.initials: T
authors.lastname: Nijenhuis
mesh_terms: D000818:Animals; D015536:Down-Regulation; D051379:Mice; D047495:PPAR gamma / Q000502:physiology*; D050199:Podocytes / Q000187:drug effects*; D011507:Proteinuria / Q000517:prevention & control*; D051381:Rats; D000068677:Sildenafil Citrate / Q000627:therapeutic use*; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors*; D000074287:TRPC6 Cation Channel
chemical_list: D047495:PPAR gamma; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C492146:Trpc6 protein, mouse; D000068677:Sildenafil Citrate
keywords: albuminuria; focal segmental glomerulosclerosis; glomerulosclerosis; ion channel; podocyte; signaling