MiR-199b-3p prevent the epithelial-mesenchymal transition (EMT) and fibrosis of renal tubule by regulating E-cadherin through targeting KDM6A in Diabetic nephropathy (DN)

Abstract Background Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Although dysfunction of renal tubule, also exhibited as epithelial-mesenchymal transition (EMT) and fibrosis, is closely associated with DN, the mechanism underlying renal tubule dysfunction still remains obscure. Methods Here, we identify that miR-199b-3p protect renal tubule from diabetic- induced injury by repressing KDM6A, a histone lysine demethylase reinforcing diabetic renal tubule dysfunction through regulating E-cadherin expression. We investigated the relationship between KDM6A, E-cadherin and miR-199b-3p with a series of gain- and loss- function assay in different cell models and animal models. The expression of KDM6A, E-cadherin and miR-199b-3p was tested by qPCR, western bolt or IHC. The EMT was measured by wound healing assay. The dysfunction of renal tubule were observed through HE and PAS stain and the kidney functions were monitored through several pathological signs detection assay, such as albumin to creatinine ratio (ACR), blood urea nitrogen (BUN), creatinine (Cr), proteinuria. Results Lower expression of E-cadherin was related to a higher level of KDM6A, while E-cadherin was increased with KDM6A-inhibitor GSK-J4 treatment both in HG-induced HK-2 cells and STZ-induced kidney. However, the variable expression of E-cadherin caused by overexpression or silence RNA was failed to alter the KDM6A expression. The target prediction and dual-luciferase assay results showed miR-199b-3p is a new miRNA targeting KDM6A. Overexpression of miR-199b-3p increased E-cadherin expression and prevented EMT through repressing KDM6A expression in HG-induced HK-2 cells, whereas miR-199b-3p knockdown by inhibitor displayed opposite results with lower E-cadherin and worse EMT accompanying with higher level of KDM6A. In addition, the miR-199b-3p knockout mice exhibited more dysfunctional renal tubule and more serious damage in kidney tissue treated with STZ. Conclusions These results demonstrate that miR-199b-3p improve E-cadherin expression and prevent the progression of DN through targeting KDM6A. MiR-199b-3p could be a potential biomarker or target for the diagnosis and treatment of diabetic nephropathy in the future.