HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 295/6/F1705    most recent 00043.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Xia, L. Articles by Whiteside, C. I. Search for Related Content PubMed PubMed Citation Articles by Xia, L. Articles by Whiteside, C. I.

High glucose activates PKC- and NADPH oxidase through autocrine TGF-β₁ signaling in mesangial cells

¹University Health Network, ²Mt. Sinai Hospital, and ³Department of Medicine, University of Toronto, Toronto, Ontario, Canada

Submitted 25 January 2008 ; accepted in final form 17 September 2008

Conversion of normally quiescent mesangial cells into extracellular matrix-overproducing myofibroblasts in response to high ambient glucose and transforming growth factor (TGF)-β₁ is central to the pathogenesis of diabetic nephropathy. Previously, we reported that mesangial cells respond to high glucose by generating reactive oxygen species (ROS) from NADPH oxidase dependent on protein kinase C (PKC) - activation. We investigated the role of TGF-β₁ in this action of high glucose on primary rat mesangial cells within 1–48 h. Both high glucose and exogenous TGF-β₁ stimulated PKC- kinase activity, as measured by an immune complex kinase assay and immunofluorescence confocal cellular imaging. In high glucose, Akt Ser473 phosphorylation appeared within 1 h and Smad2/3 nuclear translocation was prevented with neutralizing TGF-β₁ antibodies. Neutralizing TGF-β₁ antibodies, or a TGF-β receptor kinase inhibitor (LY364947), or a phosphatidylinositol 3,4,5-trisphosphate (PI3) kinase inhibitor (wortmannin), prevented PKC- activation by high glucose. TGF-β₁ also stimulated cellular membrane translocation of PKC-, -β₁, -, and -, similar to high glucose. High glucose and TGF-β₁ enhanced ROS generation by mesangial cell NADPH oxidase, as detected by 2,7-dichlorofluorescein immunofluorescence. This response was abrogated by neutralizing TGF-β₁ antibodies, LY364947, or a specific PKC- pseudosubstrate peptide inhibitor. Expression of constitutively active PKC- in normal glucose caused upregulation of p22^phox, a likely mechanism of NADPH oxidase activation. We conclude that very early responses of mesangial cells to high glucose include autocrine TGF-β₁ stimulation of PKC isozymes including PI3 kinase activation of PKC- and consequent generation of ROS by NADPH oxidase.

reactive oxygen species; transforming growth factor-β₁; PI3 kinase

This article has been cited by other articles:

				J. Ren, V. C. Hascall, and A. Wang Cyclin D3 Mediates Synthesis of a Hyaluronan Matrix That Is Adhesive for Monocytes in Mesangial Cells Stimulated to Divide in Hyperglycemic Medium J. Biol. Chem., June 12, 2009; 284(24): 16621 - 16632. [Abstract] [Full Text] [PDF]

				X. F. Wei, Q. G. Zhou, F. F. Hou, B. Y. Liu, and M. Liang Advanced oxidation protein products induce mesangial cell perturbation through PKC-dependent activation of NADPH oxidase Am J Physiol Renal Physiol, February 1, 2009; 296(2): F427 - F437. [Abstract] [Full Text] [PDF]