Glutaredoxin 1 promotes intestinal epithelial cell copper toxicity in inflammatory bowel disease

Protein S-glutathionylation (PSSG), a redox-sensitive post-translational modification, regulates protein conformation and activity, potentially resulting in cell death. PSSG is dynamically reversed by glutaredoxin 1 (GRX1), a critical oxidoreductase. Here, we observed elevated PSSG levels in colonic tissues of ulcerative colitis (UC) patients and experimental mouse models. Quantitative redox proteomics revealed glutathione disulfide oxidoreductase activity as the most significantly altered pathway in UC patients compared to controls. Interestingly, GRX1 undergoes site-specific S-glutathionylation at its catalytic Cys8 residue in UC patients, resulting in enzymatic inactivation. Grx1 deficiency exacerbated colonic PSSG accumulation and increased susceptibility to dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis, whereas Grx1 overexpression attenuated PSSG and ameliorated disease severity. Transcriptomic profiling identified GRX1 as a regulator of metal ion transmembrane transport, with Grx1 loss inducing copper overload and cuproptosis in vitro. Copper chelation therapy rescued colitis progression in Grx1^-/- mice. Mechanistically, GRX1 associates with ATPase copper-transporting beta (ATP7B), a key regulator of cellular copper export and homeostasis, thereby stabilizing the protein by suppressing ubiquitin-mediated degradation. Therapeutic upregulation of GRX1 via pirfenidone administration mitigated DSS-induced colitis. Our findings establish GRX1 as a guardian against copper toxicity and cell death in colitis and propose GRX1 activation as a novel therapeutic strategy for UC. Directly visualizing cuproptosis in vivo would represent a critical direction for future research.