miR-200a Prevents Renal Fibrogenesis Through Repression of TGF-β2 Expression

  1. Phillip Kantharidis1
  1. 1Diabetes Division, JDRF Danielle Alberti Memorial Centre for Diabetes Complications, Melbourne, Australia;
  2. 2Muscle Biology and Therapeutics, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
  1. Corresponding author: Phillip Kantharidis, phillip.kantharidis{at}bakeridi.edu.au.

Abstract

OBJECTIVE Progressive fibrosis in the diabetic kidney is driven and sustained by a diverse range of profibrotic factors. This study examines the critical role of microRNAs (miRNAs) in the regulation of the key fibrotic mediators, TGF-β1 and TGF-β2.

RESEARCH DESIGN AND METHODS Rat proximal-tubular epithelial cells (NRK52E) were treated with TGF-β1 and TGF-β2 for 3 days, and expression of markers of epithelial-to-mesenchymal transition (EMT) and fibrogenesis were assessed by RT-PCR and Western blotting. The expression of miR-141 and miR-200a was also assessed, as was their role as translational repressors of TGF-β signaling. Finally, these pathways were explored in two different mouse models, representing early and advanced diabetic nephropathy.

RESULTS Both TGF-β1 and TGF-β2 induced EMT and fibrogenesis in NRK52E cells. TGF-β1 and TGF-β2 also downregulated expression of miR-200a. The importance of these changes was demonstrated by the finding that ectopic expression miR-200a downregulated smad-3 activity and the expression of matrix proteins and prevented TGF-β–dependent EMT. miR-200a also downregulated the expression of TGF-β2, via direct interaction with the 3′ untranslated region of TGF-β2. The renal expression of miR-141 and miR-200a was also reduced in mouse models representing early and advanced kidney disease.

CONCLUSIONS miR-200a and miR-141 significantly impact on the development and progression of TGF-β–dependent EMT and fibrosis in vitro and in vivo. These miRNAs appear to be intricately involved in fibrogenesis, both as downstream mediators of TGF-β signaling and as components of feedback regulation, and as such represent important new targets for the prevention of progressive kidney disease in the context of diabetes.

Footnotes

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  • Received June 28, 2010.
  • Accepted October 1, 2010.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

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  1. Diabetes vol. 60 no. 1 280-287
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