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Inflammation is a key contributor to diabetic kidney disease pathogenesis, including reactive oxidation stress (ROS)‐mediated nuclear factor‐κB (NF‐κB) signaling pathway. In this study, we examined the effect of Astragaloside IV (AS‐IV) on anti‐inflammatory and anti‐oxidative properties under high glucose (HG) condition and the potential mechanism in glomerular mesangial cells (GMCs). We showed that AS‐IV concentration‐dependently reduced GMCs proliferation, restrained ROS release and hydrogen peroxide content, and suppressed pro‐inflammatory cytokines as well as pro‐fibrotic factors expression, which were associated with the inhibition of NF‐κB and nuclear factor‐erythroid 2‐related factor 2 (Nrf2) signaling activation. Accordingly, both NF‐κB overexpression by using RNA plasmid and Nrf2 gene silencing by using RNA interference weakened the ability of AS‐IV to ameliorate HG‐induced oxidative stress, inflammation, and cell proliferation. Furthermore, phosphatidylinositide 3‐kinases (PI3K)/serine/threonine protein kinase (Akt) and extracellular regulated protein kinases (ERK) signaling pathway regulated the process of AS‐IV‐induced Nrf2 activation and antioxidant capacity, which evidenced by using PI3K inhibitor LY294002 or ERK inhibitor PD98059 that largely abolished the AS‐IV efficacy. Taken together, these results indicated that AS‐IV protected against HG‐induced GMCs damage by inhibiting ROS/NF‐kB‐induced increases of inflammatory cytokines, fibrosis biomarkers, and cell proliferation via up‐regulation of Nrf2‐dependent antioxidant enzyme expression, which were mediated by PI3K/Akt and ERK signaling pathway activation. [ABSTRACT FROM AUTHOR]

Retention of metabolic end-products in the bodily fluids of patients with chronic kidney disease (CKD) may lead to uremia. The uremic toxin indoxyl sulfate (IS), a tryptophan metabolite, is an endogenous ligand of aryl hydrocarbon receptor (AhR). It is clarified that the upregulation and activation of AhR by IS in tubular epithelial cells (TECs) promote renal senescence and fibrosis. Renal TEC-specific knockout of AhR attenuates renal senescence and fibrosis, as well as the suppression of PGC1α-mediated mitochondrial biogenesis in ischemia reperfusion (IR)- or IS-treated CKD mice kidneys. Overexpression of peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC1α) attenuates IS-induced cell senescence and extracellular matrix production in cultured TECs. Mechanistically, AhR is able to interact with PGC1α and promotes the ubiquitin degradation of PGC1α via its E3 ubiquitin ligase activity. In summary, the elevation and activation of AhR by the accumulated uremic toxins in the progression of CKD accelerate renal senescence and fibrosis by suppressing mitochondrial biogenesis via promoting ubiquitination and proteasomal degradation of PGC1α., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA) plays a central role in the pathogenesis of diabetes. This protein has been recognized as a potential target for diabetic therapy. In this study, we identified astragaloside IV (AS-IV) as a potent modulator of SERCA inhibiting renal injury in diabetic status. Increasing doses of AS-IV (2, 6, and 18 mg kg -1 day -1 ) were administered intragastrically to db/db mice for 8 weeks. Biochemical and histopathological approaches were conducted to evaluate the therapeutic effects of AS-IV. Cultured mouse podocytes were used to further explore the underlying mechanism in vitro . AS-IV dose-dependently increased SERCA activity and SERCA2 expression, and suppressed ER stress-mediated and mitochondria-mediated apoptosis in db/db mouse kidney. AS-IV also normalized glucose tolerance and insulin sensitivity, improved renal function, and ameliorated glomerulosclerosis and renal inflammation in db/db mice. In palmitate stimulated podocytes, AS-IV markedly improved inhibitions of SERCA activity and SERCA2 expression, restored intracellular Ca 2+ homeostasis, and attenuated podocyte apoptosis in a dose-dependent manner with a concomitant abrogation of ER stress as evidenced by the downregulation of GRP78, cleaved ATF6, phospho-IRE1α and phospho-PERK, and the inactivation of both ER stress-mediated and mitochondria-mediated apoptotic pathways. Furthermore, SERCA2b knockdown eliminated the effect of AS-IV on ER stress and ER stress-mediated apoptotic pathway, whereas its overexpression exhibited an anti-apoptotic effect. Our data obtained from in vivo and in vitro studies demonstrate that AS-IV attenuates renal injury in diabetes subsequent to inhibiting ER stress-induced podocyte apoptosis through restoring SERCA activity and SERCA2 expression.