miR-1225-3p regulates fibrosis in mesangial cells via SMURF2-mediated ubiquitination of ChREBP in diabetic kidney disease.

Background: Diabetic kidney disease (DKD), characterized by mesangial fibrosis and renal dysfunction, is a major microvascular complication of diabetes. Studies have shown that miRNAs are closely related to the progression of DKD. Therefore, in this study, we aimed to explore whether miR-1225-3p can regulate Smad ubiquitin regulatory factor 2 (SMURF2)-mediated carbohydrate response element binding protein (ChREBP) ubiquitination through Rho GTPase-activating protein 5 (ARHGAP5) to affect fibrosis in DKD.

Methods: DKD mice were established by intraperitoneally injecting streptozocin (STZ), and a DKD cell model was generated by culturing in media supplemented with 25 mmol/L glucose (high glucose, HG). StarBase was used to predict the target binding sites between miR-1225-3p and ARHGAP5, and a dual-luciferase reporter gene assay was used to verify this relationship. Western blotting, RT-qPCR, flow cytometry, immunoprecipitation, ELISAs, HE staining, and Masson staining were used to detect relevant indicators.

Results: ARHGAP5 and SMURF2 expression was decreased, but ChREBP was highly expressed in the renal tissue of DKD mice and HG-induced mouse mesangial cells (MMCs). miR-1225-3p could target and regulate the transcription of ARHGAP5, and an association between ARHGAP5 and SMURF2 was revealed. miR-1225-3p facilitated fibrosis and oxidative stress in MCCs by inhibiting ARHGAP5. In addition, SMURF2 promoted the ubiquitination of HA-ChREBP, and miR-1225-3p facilitated fibrosis and oxidative stress by mediating the ARHGAP5/SMURF2-mediated ubiquitination of ChREBP in MCCs. Furthermore, the miR-1225-3p inhibitor inhibited fibrosis and inflammation in the renal tissues of DKD mice.

Conclusion: miR-1225-3p facilitates fibrosis and oxidative stress by mediating ARHGAP5/SMURF2-mediated ubiquitination of ChREBP.