MTORC1 Activation in Podocytes is a Critical Step in the Development of Diabetic Nephropathy in Mice

Overview

Journal J Clin Invest

Specialty General Medicine

Date 2011 May 25

PMID 21606597

Citations 294

Authors

Ken Inoki

Hiroyuki Mori

Junying Wang

Tsukasa Suzuki

Sungki Hong

Sei Yoshida

Simone M Blattner

Tsuneo Ikenoue

Markus A Ruegg

Michael N Hall

David J Kwiatkowski

Maria P Rastaldi

Tobias B Huber

Matthias Kretzler

Lawrence B Holzman

Roger C Wiggins

Kun-Liang Guan

Affiliations

Soon will be listed here.

Abstract

Diabetic nephropathy (DN) is among the most lethal complications that occur in type 1 and type 2 diabetics. Podocyte dysfunction is postulated to be a critical event associated with proteinuria and glomerulosclerosis in glomerular diseases including DN. However, molecular mechanisms of podocyte dysfunction in the development of DN are not well understood. Here we have shown that activity of mTOR complex 1 (mTORC1), a kinase that senses nutrient availability, was enhanced in the podocytes of diabetic animals. Further, podocyte-specific mTORC1 activation induced by ablation of an upstream negative regulator (PcKOTsc1) recapitulated many DN features, including podocyte loss, glomerular basement membrane thickening, mesangial expansion, and proteinuria in nondiabetic young and adult mice. Abnormal mTORC1 activation caused mislocalization of slit diaphragm proteins and induced an epithelial-mesenchymal transition-like phenotypic switch with enhanced ER stress in podocytes. Conversely, reduction of ER stress with a chemical chaperone significantly protected against both the podocyte phenotypic switch and podocyte loss in PcKOTsc1 mice. Finally, genetic reduction of podocyte-specific mTORC1 in diabetic animals suppressed the development of DN. These results indicate that mTORC1 activation in podocytes is a critical event in inducing DN and suggest that reduction of podocyte mTORC1 activity is a potential therapeutic strategy to prevent DN.

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