miR-21 overexpression enhances TGF-β1-induced epithelial-to-mesenchymal transition by target smad7 and aggravates renal damage in diabetic nephropathy

• Published in: Molecular and cellular endocrinology 2014-07, Vol.392 (1-2), p.163-172
• Main Authors: Wang, Jin-Yang, Gao, Yan-Bin, Zhang, Na, Zou, Da-Wei, Wang, Peng, Zhu, Zhi-Yao, Li, Jiao-Yang, Zhou, Sheng-Nan, Wang, Shao-Cheng, Wang, Ying-Ying, Yang, Jin-Kui
• Format: Article
• Language: English
• Subjects: Actins - metabolism; Animals; Base Sequence; Biomarkers - metabolism; Cadherins - metabolism; Cell Line; Diabetic Nephropathies - genetics; Diabetic Nephropathies - pathology; Diabetic nephropathy; Down-Regulation - drug effects; Epithelial-Mesenchymal Transition - drug effects; Epithelial-Mesenchymal Transition - genetics; Epithelial-to-mesenchymal transition; Humans; Kidney - drug effects; Kidney - pathology; Kidney - ultrastructure; Male; Mice, Inbred C57BL; MicroRNA(miR); MicroRNAs - genetics; MicroRNAs - metabolism; Molecular Sequence Data; Phosphorylation - drug effects; Renal interstitial fibrosis; Smad3 Protein - genetics; Smad3 Protein - metabolism; Smad7 Protein - genetics; Smad7 Protein - metabolism; TGF-β1; Transforming Growth Factor beta1 - pharmacology; Up-Regulation - drug effects
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/j.mce.2014.05.018

[Display omitted] •miR-21 expression was upregulated by TGF-β1 in time- and concentration-dependent manner.•miR-21 over-expression enhanced TGF-β1-induced EMT by directly down-regulating smad7 and indirectly up-regulating smad3.•miR-21 inhibitor can not only inhibit EMT and fibrosis but also ameliorate renal structure and function.•Targeting miR-21 may be a better alternative to directly suppress TGF-β1-mediated fibrosis in DN. Epithelial-to-mesenchymal transition (EMT) plays an important role in renal interstitial fibrosis (RIF) with diabetic nephropathy (DN). Smad7 (a inhibitory smad), a downstream signaling molecules of TGF-β1, represses the EMT. The physiological function of miR-21 is closely linked to EMT and RIF. However, it remained unclear whether miR-21 over-expression affected TGF-β1-induced EMT by regulating smad7 in DN. In this study, real-time RT-PCR, cell transfection, luciferase reporter gene assays, western blot and confocal microscope were used, respectively. Here, we found that miR-21 expression was upregulated by TGF-β1 in time- and concentration -dependent manner. Moreover, miR-21 over-expression enhanced TGF-β1-induced EMT(upregulation of a-SMA and downregulation of E-cadherin) by directly down-regulating smad7/p-smad7 and indirectly up-regulating smad3/p-smad3, accompanied by the decrease of Ccr and the increase of col-IV, FN, the content of collagen fibers, RTBM, RTIAW and ACR. Meantime, the siRNA experiment showed that smad7 can directly regulate a-SMA and E-cadherin expression. More importantly, miR-21 inhibitor can not only inhibit EMT and fibrosis but also ameliorate renal structure and function. In conclusion, our results demonstrated that miR-21 overexpression can contribute to TGF-β1-induced EMT by inhibiting target smad7, and that targeting miR-21 may be a better alternative to directly suppress TGF-β1-mediated fibrosis in DN.