Promoting ubiquitin-dependent Drp1 degradation contributes to the protective effect of Astragalin against diabetic renal fibrosis

Diabetic kidney disease (DKD) is a severe complication of diabetes. Fibrosis is an irreversible pathological change closely associated with the development of disease. Disrupted mitochondrial dynamics involved in the progression of fibrosis. Astragalin (AG) exhibits therapeutic potential for DKD. However, the effects of AG on renal fibrosis, as well as precise target and underlying mechanisms, remain largely unexplored. Here, we report the alleviation of diabetes-induced renal fibrosis by AG and the mechanism of regulating dynamin-related protein1 (Drp1)-mediated mitochondrial dynamics. A diabetic mouse model was induced by streptozotocin and treated with AG for 8 weeks. In vitro, HK2 cells were treated with high glucose and lipids. Mitochondrial morphology and function were assessed to explore the mechanisms. The results demonstrated that AG significantly alleviated renal fibrosis, mitochondrial damage and inhibited renal tubular cell Apoptosis in diabetic mice. In vitro, AG reduced Drp1 protein levels, inhibited excessive mitochondrial fission and restored mitochondrial function. Mechanistically, knockdown of Drp1 with siRNA and Drp1 overexpression further verified the effects of AG. Additionally, Cellular thermal shift assay (CETSA) and immunoprecipitation (IP) results confirmed the interaction between AG and Drp1. These findings suggested that Drp1 may serve as a key target for AG to exhibit the benefits. Furthermore, the Proteasome Inhibitor MG132 abolished the effects of AG, indicating that AG reduced Drp1 expression by enhancing its degradation via the ubiquitin-proteasome pathway. In conclusion, our data suggest that AG may be a potential therapeutic agent for diabetic renal fibrosis by inhibiting mitochondrial excessive fission through promoting ubiquitin-dependent Drp1 degradation.

Astragalin; Diabetic kidney disease; Drp1; Kidney fibrosis; Mitochondrial dynamic.