SIRT3 regulates GLS1 K311 acetylation to restrain glutamate-driven ferroptosis in renal fibrosis.

Abstract

Renal tubulointerstitial fibrosis is a final common pathway of chronic kidney disease (CKD), but the metabolic mechanisms linking mitochondrial dysfunction to ferroptotic tubular injury remain incompletely defined. We found that a SIRT3-GLS1-glutamate-p53/SLC7A11 pathway links mitochondrial deacetylation to ferroptosis and renal fibrosis. SIRT3 expression was reduced in human CKD kidneys and UUO-induced fibrotic mouse kidneys and correlated positively with eGFR and negatively with albuminuria. Sirt3 deletion aggravated renal dysfunction, mitochondrial injury, lipid peroxidation and fibrotic remodeling, whereas AAV-mediated Sirt3 restoration was protective. In HK-2 cells, SIRT3 loss increased susceptibility to TGF-β1-induced ferroptosis. Transcriptomic and functional analyses identified GLS1-dependent glutamate accumulation as a major downstream consequence of SIRT3 loss. LC-MS/MS confirmed dynamic acetylation of GLS1 at K311, while mutagenesis, cycloheximide-chase and ubiquitination assays showed that K311 status regulated GLS1 ubiquitination and protein stability. Pharmacological GLS1 inhibition attenuated glutamate accumulation and ferroptotic injury. Glutamate activated p53 signaling, reduced SLC7A11/GPX4, and increased lipid peroxidation; p53 inhibition and ChIP-qPCR supported p53-dependent repression of SLC7A11. SLC7A11 restoration rescued SIRT3-deficiency-induced ferroptosis in vitro and in vivo. Finally, candesartan preferentially bound SIRT3 over comparator ARBs and suppressed ferroptosis in a SIRT3-dependent manner. SIRT3-dependent regulation of GLS1 therefore links glutamate stress to ferroptosis during renal fibrosis.