miR302a-3p May Modulate Renal Epithelial-Mesenchymal Transition in Diabetic Kidney Disease by Targeting ZEB1

Recent study found that microRNA (miRNA) are involved in diabetic kidney disease (DKD). The objective of this study is to determine the role of miR302a-3p in the process of renal epithelial-mesenchymal transition (EMT) in DKD.

The miRNA expression profiling of the cell line stimulated by high glucose was performed by a microarray analysis. Then real-time polymerase chain reaction (PCR) were used to determine the expression of one of the miRNAs significantly upregulated in cell line stimulated by high glucose, miR302a-3p. miR302a-3p mimics and inhibitor were transfected to HK-2 cells following exposure to high glucose and normal glucose, respectively. The expressions of E-cadherin, vimentin, and Zinc finger E-box-binding protein 1 (ZEB-1) were determined by real-time PCR and Western blot. Finally, the levels of miR302a-3p in the plasma of DKD patients were detected by real-time PCR, and then the relationship of miR302a-3p and urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) was analyzed.

The expression of miR-302a-3p, 513a-5p, 1291 and the other 17 miRNA were increased significantly in HK-2 cell line after high glucose stimulation; on the other hand, miRNA490-3p, 638, 3203 and the other 19 miRNA were decreased significantly. In vitro, miR-302a-3p expression in HG group increased at 6 h and ascended to the highest level at 12 and 24 h and then gradually decreased from 48 to 72 h. More interesting, ZEB1 protein expression had an opposite change, which gradually decreased from 6 to 24 h and then gradually increased from 48 to 72 h. Moreover, overexpression of miR-302a-3p suppressed expression of ZEB1 in the post-transcriptional level and reversed high glucose-mediated downregulation of E-cadherin and upregulation of vimentin. Meanwhile, loss of miR-302a-3p expression can lead to EMT of HK-2 cells just as high glucose stimulation. Further study demonstrated that the expression of circulating miR-302a-3p was significantly increased in the diabetes mellitus (DM) with normoalbuminuria (DM group, n = 22) compared with control (healthy persons, n = 30) and then decreased in DM with microalbuminuria (DNE group, n = 20). Furthermore, its expression in DM with macroalbuminuria (DNC group, n = 18) was decreased significantly compared with DM group. Circulating miR-302a-3p had negative relevance with UAE in DNE group (r = -0.649, p = 0.002) and DNC group (r = -0.681, p = 0.006). Circulating miR-302a-3p had positive relevance with eGFR in DNC group (r = 0.486, p = 0.041).

These findings suggest that miR-302a-3p may play a protective role by targeting ZEB1 in renal EMT in DKD. In view of these findings, it is conceivable that miR-302a-3p may serve as a potential novel target in pre-EMT states for the amelioration renal fibrosis seen in DKD.