MiR-192-5p targets cell cycle regulation in diabetic kidney disease via cyclin-dependent kinase inhibitor 3.

Diabetic kidney disease (DKD), a.k.a diabetic nephropathy, is a leading cause of end-stage renal disease. However, in a fair percentage of patients with type-2 diabetes, renal involvement also occurs due to non-diabetic reasons (non-diabetic kidney disease, NDKD). In this study, we identified miRNA-mRNA regulatory networks specific to human DKD pathogenesis. miRNA profiling of the renal biopsy from cases (DKD, n = 5), disease controls (T2DM with NDKD, n = 6), and non-diabetic, non-CKD controls (patients undergoing nephrectomy for renal cancer, n = 3) revealed 68 DKD-specific miRNA regulation. Sixteen target mRNAs of these DKD-miRNAs were found to have a negative association with the estimated glomerular filtration rate (eGFR) in patients with DKD. The renal gene expression and eGFR data of DKD patients (n = 10-18) in the NephroSeq database were used. Based on these findings, 11 miRNA-mRNA regulatory networks were constructed for human DKD pathogenesis. Of these, in-vitro validation of miR-192-5p- CDKN3 (Cell cycle-dependent kinase inhibitor 3) network was done as miR-192-5p exhibited a maximum number of target genes in the identified DKD regulatory networks, and CDKN3 appeared as a novel target of miR-192-5p in our study. We demonstrated that miR-192-5p overexpression or knockdown of CDKN3 attenuated high glucose-induced apoptosis, fibrotic gene expression, cell hypertrophy, and cell cycle dysregulation and improved viability of proximal tubular cells. Moreover, miR-192-5p overexpression significantly inhibited CDKN3 mRNA and protein expression in proximal tubular cells. Overall, 11 miRNA-mRNA regulatory networks were predicted for human DKD pathogenesis; among these, the association of miR-192-5p- CDKN3 network DKD pathogenesis was confirmed in proximal tubular cell culture.