MiR-455-3p suppresses renal fibrosis through repression of ROCK2 expression in diabetic nephropathy

Highlights: • Downregulation of miR-455-3p expression in DN. • ROCK2 as a target of miR-455-3p. • Re-introduction of ROCK2 attenuated the effect of miR-455-3p on cell proliferation, ECM accumulation and EMT in vitro. • Reductions in proinflammatory levels and renal fibrosis by miR-455-3p usages, in vivo. Emerging evidence has shown that microRNAs (miRNAs) play a mediatory role in the pathogenesis of diabetic nephropathy (DN), but the function of the involved miRNAs is still incomplete. Here, we found that miR-455-3p was down-regulated in the human mesangial cells (HMC) and human proximal tubule epithelial cells (HK-2) stimulated with high glucose (HG) or transforming growth factor beta 1 (TGF-β1). Rho-associated coiled coil-containing protein kinase 2 (ROCK2) was identified as a directed target of miR-455-3p. Overexpression of ROCK2 significantly attenuated the inhibitory effects of miR-455-3p on cell proliferation, extracellular matrix (ECM) synthesis and epithelial-mesenchymal transition (EMT) in HG-treated cells. Furthermore, the DN model was prepared by using high-fat feeding combined with Streptozotocin (STZ) induced rats, and the DN group was treated by injecting miR-455-3p agomir. The results of periodic acid-Schiff (PAS) and Masson staining showed that miR-455-3p overexpression improved the pathological changes of glomerular hypertrophy, mesangial amplification, and renal fibrosis. Additionally, miR-455-3p overexpression decreased ROCK2, proliferating cell nuclear antigen (PCNA) and Collagen I levels, and also reduced inflammatory cytokines TNF-α, MCP-1 and IL-1β levels in vivo. Altogether, these results suggest that miR-455-3p plays an essential role in the treatment of renal fibrosis through repressing ROCK2 expression; and miR-455-3p might be an effective therapy for DN.