Sodium aescinate induces renal cell ferroptosis through the ATF4/CTH/SQOR axis

Sodium aescinate (SA), derived from seeds of the Chinese herb Suoluozi ( Aesculus wilsonii Rehd.), has been linked to severe kidney injury during clinical use. We previously found that SA induces nephrocyte ferroptosis, and upregulation of glutathione peroxidase 4 (GPX4) or ferroptosis suppressor protein 1 (FSP1) expression only partially attenuates this toxic effect. In this study, we demonstrated that SA reduced cellular levels of hydrogen sulfide (H 2 S) and reduced coenzyme Q10 (CoQ10H 2 ), leading to impaired antioxidant defense and lipid peroxidation (LPO) in renal cells. Mechanistically, SA suppressed the expression of activating transcription factor 4 (ATF4), cystathionine γ-lyase (CTH) and sulfide: quinone oxidoreductase (SQOR). The SA-induced downregulation of CTH expression was attributed to the decreased recruitment of ATF4 to the cis -regulatory element (CRE) of the CTH promoter. ATF4 overexpression in SA-treated cells upregulated CTH expression, which elevated H 2 S and CoQ10H 2 levels, improved antioxidant defense, and reduced ferroptosis. Critically, CTH silencing completely abrogated these protective effects. Conversely, CTH or SQOR overexpression, or H 2 S supplementation restored CoQ10H 2 levels and protected against SA-induced ferroptosis. However, in SQOR-deficient cells, neither intervention rescued CoQ10H 2 nor alleviated nephrotoxicity despite increased H 2 S levels. Additionally, alternative oxidase (AOX) overexpression abolished the protective effect of the ATF4/CTH/SQOR axis by oxidizing CoQ10H 2 back to its inactive form. In conclusion, SA induced ferroptosis-mediated kidney injury by disrupting the ATF4/CTH/SQOR axis, leading to reduced CoQ10H 2 levels and impaired redox homeostasis. This study introduces this pathway as a novel therapeutic target for SA-induced nephrotoxicity.