MiR-133b Improve Renal Interstitial Fibrosis By Regulation Of CTGF Expression In The Elderly Mice

Objective: Renal interstitial fibrosis is the pathological basis of renal aging and progression to end-stage renal disease. Renal epithelial mesenchymal transition(EMT) is an important step in the development of renal interstitial fibrosis.In our previous studies,we found that there was a difference in the expression of miR-133b in mesenchymal stem cells derived from bone marrow in young and aged rats, and miR-133b inhibited EMT in renal tubular epithelial cells induced by transforming growth factor beta 1(TGF-?1). This study was to investigate the role and mechanism of miR-133b in the regulation of renal interstitial fibrosis.Methods: The expression of miR-133b was detected by RT-PCR in different concentrations (0?6?8?10ng/ml) and different time (0?24?48?72h) of TGF-1in HK2 cells. Using dual-luciferase reporter gene to detect the miR-133b target.TGF-(31 and miR-133b combined treatment of HK2,Western blot and PCR detection of EMT sign factor expression of E-cadherin,a-SMA,Fn,Col3Al and miR-133's target. Build CTGF expression vectors,and HK2 cells transfected by miR-141 common Western blot detection of miR-133 target expression. Construct the UUO model of aged mice, and use the transfection reagent to inject miR-133b into aged mice, and the miR-133b, miR-133 target and protein expression and mRNA level of EMT sign factor were detected on seventh and fourteenth days.Result: The expression of miR-133b decreased gradually with the increase of the concentration of TGF- 1 1 and the prolongation of the intervention time. The expression of miR-133b was down regulated (p<0.01) when the concentration of TGF- was about 8 ng/ml. Transfection of miR-133b mimic could down regulate the expression of CTGF(p<0.05), but the transfection of miRNA mimic control had no effect on the expression of CTGF, and the double luciferase reporter gene assay confirmed that CTGF was a direct target of miR-133b. Transfection of miR-133b mimic inhibited the down-regulation of E-cadherin and the up-regulation of a-SMA, FN and Col3Al (p<0.05) in HK2 cells induced by TGF- beta cells. Overexpression of CTGF can reverse the inhibitory effect of miR-133b on EMT. The expression of miRNA-133b in the kidney of mice was significantly higher (about 70-100 times) through intravenous injection of miR-133b.Pathological staining and Western blot results showed that transfection of miR-133b could significantly improve the renal tubular atrophy and interstitial fibrosis in aged UUO mice.Conclusion: MiR-133b can inhibit the expression of CTGF,and inhibit the EMT in HK2 cells induced by TGF- 1, and alleviate the renal interstitial fibrosis in aged UUO mice.