miR-192 prevents renal tubulointerstitial fibrosis in diabetic nephropathy by targeting Egr1

Diabetic nephropathy (DN), as the most common and serious diabetic microvascular complication, has become the first cause of end-stage renal disease (ESRD) in many countries and regions. However, the pathogenesis of renal fibrosis during the development of DN remains unknown.

The expression levels of miR-192 and early growth response factor 1 (Egr1) were determined by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and Western blotting in the renal tissues of Otsuka-Long-Evans-Tokushima-Fatty (OLETF) and Long-Evans-Tokushima-Otsuka (LETO) rats. The diabetic kidney environment was simulated by a high-sugar medium. The expression levels of miR-192 and Egr1 were further measured in the HK-2 cell line. Egr1 was verified as a potential target of miR-192 by using bioinformatics analysis and luciferase activity assay. The expression level of Egr1 was determined by overexpressing and knocking down the expression of miR-192. In addition, Western blotting was used to determine changes in Transforming growth factor-beta 1 (TGF-β1) and fibronectin (FN).

Compared with the kidney tissue of LETO rats, the expression of miR-192 was decreased in OLETF rats, whereas the expression of Egr1 was increased. We found the same phenomenon in the HK-2 cell line cultured in the high-glucose medium. Next, miR-192 can act on Egr1 through 3'-UTR to reduce the expression of Egr1 verified by luciferase assay. In addition, the expression levels of TGF-β1 and FN changed significantly, as the expression level of Egr1 increased or decreased.

MiR-192 causes degradation of TGF-β1 and FN through targeting Egr1 and affects the progression of TIF and even DN.