miR-382 Contributes to Renal Tubulointerstitial Fibrosis by Downregulating HSPD1.

Redox imbalance plays an important role in the pathogenesis of CKD progression. Previously, we demonstrated that microRNA-382 (miR-382) contributed to TGF-β1-induced loss of epithelial polarity in human kidney epithelial cells, but its role in the development of renal tubulointerstitial fibrosis remains unknown. In this study, we found that with 7 days of unilateral ureteral obstruction (UUO) in mice, the abundance of miR-382 in the obstructed kidney was significantly increased. Meanwhile, the protein expression of heat shock protein 60 (HSPD1), a predicted target of miR-382, was reduced after 7 days of UUO. Expression of 3-nitrotyrosine (3-NT) was upregulated, but expression of thioredoxin (Trx) was downregulated. Anti-miR-382 treatment suppressed the upregulation of miR-382, attenuated renal interstitial fibrosis in the obstructed kidney, and reversed the downregulation of HSPD1/Trx and upregulation of 3-NT after UUO. Furthermore, in vitro study revealed that overexpression of HSPD1 significantly restored Trx expression and reversed TGF-β1-induced loss of E-cadherin, while in vivo study found that direct siRNA-mediated suppression of HSPD1 in the UUO kidney promoted oxidative stress despite miR-382 blockade. Our clinical data showed that upregulation of miR-382/3-NT and downregulation of HSPD1/Trx were also observed in IgA nephropathy patients with renal interstitial fibrosis. These data supported a novel mechanism in which miR-382 targets HSPD1 and contributes to the redox imbalance in the development of renal fibrosis.