Quercetin-4'-O-β-D-glucopyranoside inhibits ferroptosis though SIRT5-mediated desuccinylation of TFR1 in diabetic nephropathy.

Diabetic nephropathy (DN) is a severe complication of diabetes, marked by podocyte injury and renal dysfunction. Quercetin-4'-O-β-D-glucopyranoside (QODG), a flavonoid glycoside, has demonstrated renal protective effects. Succinylation, a post-translational modification, plays a critical role in cellular metabolism and disease progression. This study aimed to explore whether QODG alleviates DN by modulating SIRT5-mediated desuccinylation. Mouse podocyte clone-5 (MPC5) cells were exposed to high glucose (HG) with or without QODG treatment. Cell viability was measured using the cell counting kit-8 assay. Ferroptosis was assessed via commercial kits detecting lipid peroxidation and iron accumulation. Protein expression of ferroptosis- and succinylation-related markers was evaluated by Western blot. Immunoprecipitation combined with Western blot was used to detect succinylation levels of ferroptosis-related proteins. The interaction between SIRT5 and transferrin receptor 1 (TFR1) was examined by co-immunoprecipitation and proximity ligation assay assays. Additionally, an in vivo DN model was established in mice using high-fat diet and streptozotocin administration. High glucose induced ferroptosis in MPC5 cells, as indicated by increased lipid peroxidation, iron accumulation, and dysregulation of ferroptosis-related proteins. These effects were mitigated by QODG treatment. Mechanistically, QODG upregulated SIRT5 expression, which promoted desuccinylation of TFR1 at lysine 626 site, reducing its protein stability and inhibiting ferroptosis. Moreover, knockdown of SIRT5 aggravated ferroptosis and enhanced TFR1 succinylation, whereas overexpression of TFR1 counteracted the antiferroptotic effects of SIRT5. In DN mice, QODG ameliorated renal injury, oxidative stress, and ferroptosis. QODG inhibited ferroptosis by promoting SIRT5-mediated desuccinylation of TFR1, thereby attenuating DN. These findings highlight the potential of QODG as a therapeutic agent for DN.