Abstract
Tubular injury and oxidative stress are involved in the pathogenesis of diabetic kidney disease (DKD). Astragaloside IV (ASIV) is a natural antioxidant. The effects and underlying molecular mechanisms of ASIV on DKD have not been elucidated. The db/db mice and high-glucose-stimulated HK2 cells were used to evaluate the beneficial effects of ASIV in vivo and in vitro. Succinylated proteomics was used to identify novel mechanisms of ASIV against DKD and experimentally further validated. ASIV alleviated renal dysfunction and proteinuria, downregulated fasting blood glucose, and upregulated insulin sensitivity in db/db mice. Meanwhile, ASIV alleviated tubular injury, oxidative stress, and mitochondrial dysfunction in vivo and in vitro. Mechanistically, ASIV reversed downregulated 17beta-hydroxysteroid dehydrogenase type 10 (HSD17B10) lysine succinylation by restoring carnitine palmitoyl-transferase1alpha (Cpt1a or CPT1A) activity in vivo and in vitro. Molecular docking and cell thermal shift assay revealed that ASIV may bind to CPT1A. Molecular dynamics simulations demonstrated K99 succinylation of HSD17B10 maintained mitochondrial RNA ribonuclease P (RNase P) stability. The K99R mutation of HSD17B10 induced oxidative stress and disrupted its binding to CPT1A or mitochondrial ribonuclease P protein 1 (MRPP1). Importantly, ASIV restored the interaction between HSD17B10 and MRPP1 in vivo and in vitro. We also demonstrated that ASIV reversed high-glucose-induced impaired RNase P activity in HK2 cells, which was suppressed upon K99R mutation of HSD17B10. These findings suggest that ASIV ameliorates oxidative stress-associated proximal tubular injury by upregulating CPT1A-mediated K99 succinylation of HSD17B10 to maintain RNase P activity.