title: Insulin increases filtration barrier permeability via TRPC6-dependent activation of PKGIα signaling pathways.
abstract: Podocytes are dynamic polarized cells on the surface of glomerular capillaries and an essential component of the glomerular filtration barrier. Insulin increases the activation of protein kinase G type Iα (PKGIα) subunits, leading to podocyte dysfunction. In addition, accumulating evidence suggests that TRPC6 channels are crucial mediators of podocyte calcium handling and involved in the regulation of glomerular filtration. Therefore, we investigated whether TRPC6 is involved in the regulation of filtration barrier permeability by insulin via the PKGIα-dependent manner. TRPC channel inhibitor SKF96365 abolished insulin-dependent glomerular albumin permeability and transepithelial albumin flux in cultured rat podocytes. Insulin-evoked albumin permeability across podocyte monolayers was also blocked using TRPC6 siRNA. The effect of insulin on albumin permeability was mimicked by treating podocytes with TRPC channel activator (oleolyl-2-acetyl-sn-glycerol, OAG). Insulin or OAG treatment rapidly increased the superoxide generation through activation of NADH oxidase. TRPC inhibitor SKF96365 or siRNA knockdown of TRPC6 attenuated insulin-dependent increase of ROS production. Furthermore, TRPC inhibitor or downregulation of TRPC6 blocked insulin-induced rearrangement of the actin cytoskeleton and attenuated oxidative activation of PKGIα and changes in the phosphorylation of PKG target proteins MYPT1 and MLC. Moreover insulin regulated the PKGIα interaction with TRPC6 in cultured rat podocytes. Taken together, our data suggest a key role of TRPC6 channels in the mediation of insulin-dependent activation of PKGIα signaling pathways. Overall, we have identified a potentially important mechanism that may explain disturbances in filtration barrier permeability in many diseases with increased expression of TRPC6 and chronic Ca2+overload.
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Rogacka
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Irena
authors.initials: I
authors.lastname: Audzeyenka
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Patrycja
authors.initials: P
authors.lastname: Rachubik
authors.affiliation: University of Gdańsk - Medical University of Gdańsk, Intercollegiate Faculty of Biotechnology, Laboratory of Virus Molecular Biology, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Rychłowski
authors.affiliation: University of Alabama at Birmingham, Department of Medicine, Cardio-Renal Physiology and Medicine, Birmingham, AL, USA.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Kasztan
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Jankowski
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Angielski
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland. Electronic address: apiwkowska@imdik.pan.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Piwkowska
mesh_terms: D000818:Animals; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D060730:Glomerular Filtration Barrier / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects*; D050052:TRPC Cation Channels / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D007328:Insulin; D050052:TRPC Cation Channels; C492145:Trpc6 protein, rat; D062965:Cyclic GMP-Dependent Protein Kinase Type I; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
keywords: Filtration barrier permeability; Insulin; NADPH oxidase; Podocyte; Protein kinase G type I alpha; TRPC6