title: Hydrogen peroxide induces dimerization of protein kinase G type Iα subunits and increases albumin permeability in cultured rat podocytes.
abstract: Podocytes help regulate filtration barrier permeability in the kidneys. They express contractile proteins that are characteristic of smooth muscle cells as well as receptors for vasoactive factors such as angiotensin II and atrial natriuretic peptide (ANP). The later one generates intracellular cGMP, with subsequent activation of cGMP-dependent protein kinase; PKG (isoform PKGIα and PKGIβ). In this study, we asked whether hydrogen peroxide (H(2)O(2)), a physiological vasorelaxing factor, affected podocyte permeability and the podoctye PKGIα signaling pathway. Expression of PKGIα was confirmed in cultured rat podocytes using RT-PCR, immunofluorescence, and Western blotting. Exposure of podocytes to exogenous H(2)O(2) (100 µM) in non-reducing conditions increased the formation of PKGIα interprotein disulfide bonds, affected the phosphorylation of PKG target proteins, namely MYPT1 (maximal increase of about 57% at 30 min) and MLC (maximal decrease of about 62% at 10 min). Furthermore, H(2)O(2) increased the permeability of a layer of podocytes to albumin: Transmembrane flux for albumin increased five-fold (106.6 ± 5.2 µg/ml vs. 20.2 ± 2.5 µg/ml, P < 0.05, n = 5), and the PKG inhibitor Rp-8-Br-cGMPS (100 µM) prevented the flux increase. These data suggest that oxidative modulation of PKGIα in podocytes plays an important
authors.affiliation: Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre Polish Academy of Sciences, Gdańsk, Poland. apiwkowska@cmdik.pan.pl
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Piwkowska
authors.forename: Dorota
authors.initials: D
authors.lastname: Rogacka
authors.forename: Maciej
authors.initials: M
authors.lastname: Jankowski
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kocbuch
authors.forename: Stefan
authors.initials: S
authors.lastname: Angielski
mesh_terms: D000418:Albumins / Q000493:pharmacokinetics*; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D060730:Glomerular Filtration Barrier / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D050199:Podocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D055503:Protein Multimerization / Q000187:drug effects / Q000502:physiology*; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: D000418:Albumins; D021122:Protein Subunits; D006861:Hydrogen Peroxide; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases