Astragaloside IV Protects against Diabetic Nephropathy by Inhibiting FUNDC1-Dependent Mitochondria-Associated Endoplasmic Reticulum Membranes

Studies have demonstrated the potential therapeutic effects of Astragaloside IV (AS-IV) in various diseases. However, its effect on diabetic nephropathy (DN) and the underlying mechanisms are not clear. The expression of FUNDC1 in DN patients and high glucose-induced human renal tubular epithelial cell line (HK-2) with or without AS-IV was analyzed using quantitative real-time polymerase chain reaction and Western blot. Cell Counting Kit-8 (CCK-8) assay was used to quantify cell viability. The intracellular oxygen consumption rate was measured by using the seahorse energy analyzer, and the mitochondrial reactive oxygen species and mitochondrial Ca²⁺ levels were determined by flow cytometry. A mice model of diabetes was constructed and treated with different doses of AS-IV. Hematoxylin-eosin and Masson staining were used to examine the pathological changes in renal tissue. Creatinine, blood urea nitrogen, and urinary protein were detected by the biochemical method. The results demonstrated increased FUNDC1 expression in patients with DN and high glucose-cultured HK-2 cells. FUNDC1 silencing inhibited high glucose-induced mitochondria-associated endoplasmic reticulum (ER) membrane formation and mitochondrial dysfunction in HK-2 cells. Importantly, AS-IV treatment inhibited FUNDC1-induced mitochondria-associated ER membrane formation and mitochondrial dysfunction in HK-2 cells. AS-IV treatment also protected against renal injury and improved renal function in mice. AS-IV alleviates the progression of DN by inhibiting FUNDC1-dependent mitochondria-associated ER membrane.