miR-200a Prevents Renal Fibrogenesis Through Repression of TGF-(52 Expression

摘要

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-βl and tgf-β2 for 3 days, and expression of markers of epithelial-to-mesenchy-mal 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-p 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-pl and tgf-β2 also downregu-lated 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-p 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. Diabetes 60:280-287, 2011