Insulin increases glomerular filtration barrier permeability through dimerization of protein kinase G type Iα subunits

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1832

Article

Piwkowska, Agnieszka¹  Rogacka, Dorota¹  Kasztan, Malgorzata²  Angielski, Stefan¹  Jankowski, Maciej^1,2 

[1] Polish Acad Sci, Lab Mol & Cellular Nephrol, Mossakowski Med Res Ctr, PL-80211 Gdansk, Poland

[2] Med Univ Gdansk, Dept Therapy Monitoring & Pharmacogenet, Gdansk, Poland

关键词: Filtration barrier permeability;    Insulin;    NAD(P)H oxidase;    Protein kinase G type I alpha;    Podocyte;    Hyperinsulinemia;   

DOI  :  10.1016/j.bbadis.2013.02.011

来源: Elsevier

【 摘 要 】

The increase in the permeability of the glomerular barrier filtration to albumin is a well-known feature of diabetic microvasculature and a negative prognostic factor for vascular complications. However, the underlying mechanisms are incompletely understood. We demonstrated recently that superoxide anion generation increases dimerization of protein kinase G type la (PKGI alpha) subunits, leading to podocyte dysfunction. Here we investigated whether high insulin concentration is involved in PKGI-dependent hyperpermeability of the diabetic glomerular filtration barrier. We assessed changes in insulin-induced glomerular permeability by measuring glomerular capillary permeability to albumin in isolated glomeruli from Wistar and obese and lean Zucker rats and transmembrane albumin flux in cultured rat podocytes. Expression of PKGI alpha and upstream proteins was confirmed in the podocytes using Western blotting and immunofluorescence. Insulin (300 nM, 5 mm) increased NAD(P)H-dependent glomerular albumin permeability in Wistar rats and PKGI-dependent transmembrane albumin flux in cultured podocytes. Podocyte exposure to insulin in non-reducing conditions increased PKGI alpha interprotein disulfide bond formation, altered the phosphorylation of the PKG target proteins MYPT1 and MLC, and disrupted the actin cytoskeleton. The role of NADPH oxidase (NOX) in insulin-induced reactive oxygen species (ROS) generation and insulin-evoked increases in albumin permeability in podocytes was confirmed with NOX2 and NOX4 siRNA. Glomerular albumin permeability was increased in hyperinsulinemic Zucker obese rats with isolated glomeruli showing increased expression of PKGIa and NOX4. Taken together, these data demonstrate that insulin increases glomerular barrier albumin permeability via a PKGI-dependent mechanism involving NAD(P)H-dependent generation of superoxide anion. These findings reveal a role for insulin in the pathophysiology of diabetic glomerular nephropathy. (C) 2013 Elsevier B.V. All rights reserved.

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