title: Combined effect of insulin and high glucose concentration on albumin permeability in cultured rat podocytes.
abstract: Podocytes play a fundamental role in regulating glomerular permeability to albumin. This mechanism is disrupted in the course of diabetes. Both insulin and high glucose concentrations enhance the permeability of podocytes to albumin by stimulating oxygen free radical production, primarily by NAD(P)H oxidase-4 (NOX4), and by activating protein kinase G, isoform Iα (PKGIα). However, no study has investigated the combined effects of insulin and high glucose concentration. Here, we investigated the effects of applying insulin (INS, 300 nM) and high glucose (HG, 30 mM), both separately and combined, for 5 days, on cultured rat podocyte permeability to albumin. We measured podocyte permeability with a transmembrane albumin flux assay. We measured NOX4 and PKGIα mRNA expression with real-time PCR. We used Western blots to evaluate protein expression levels of NOX4, PKGIα, the myosin-binding subunit of myosin phosphatase 1, and myosin light chain. We found that INS and HG had a synergistic effect on podocyte permeability to albumin, and this synergy was not dependent on NOX4 or PKGIα. These results suggested that the combined action of INS and HG may exacerbate glomerular dysfunction in diabetes.
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
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: 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; Department of Clinical Chemistry, Medical University of Gdańsk, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Jankowski
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism; D010539:Permeability; D050199:Podocytes / Q000378:metabolism*; D055503:Protein Multimerization; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D007328:Insulin; D012709:Serum Albumin; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498911:Nox4 protein, rat; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D005947:Glucose
keywords: Contraction apparatus; Filtration barrier permeability; High glucose concentration; Insulin; Podocytes; Protein kinase G, type Iα