GRX2-Mediated Deglutathionylation of SIRT3 Alleviates Intestinal Ischemia/Reperfusion-Induced Mitochondrial Oxidative Damage.

Aims: Mitochondrial oxidative damage is one of the factors that contributes to the pathological process of intestinal ischemia/reperfusion (II/R) injury. Glutaredoxin (GRX2), which serves as a crucial protein in maintaining mitochondrial redox homeostasis, affects the activity of downstream proteins through its deglutathionylation effect. Silent information regulator (SIRT3), a crucial deacetylase in mitochondria, has regulatory effects on the activity of various mitochondrial antioxidant enzymes. However, the precise regulatory mechanism underlying SIRT3 enzymatic activity is unknown. Our research is designed to explore GRX2-mediated SIRT3 deglutathionylation's role and mechanism in II/R injury.

Results: GRX2 levels decreased after II/R injury, and GRX2 overexpression alleviated II/R-induced intestinal mucosal injury, mitochondrial oxidative damage, damage to mitochondrial structure and function, remote organ injury, and the systemic inflammatory response. GRX2 overexpression substantially decreased the S-glutathionylation of SIRT3 and increased its activity. The results of the incubation of recombinant SIRT3 with glutathione and H₂O₂ indicated that the S-glutathionylation of SIRT3 inhibited SIRT3 activity. Subsequently, SIRT3 mutant plasmids with cysteine-to-serine substitutions were constructed to screen for the S-glutathionylation sites of SIRT3 among the four cysteine residues in its amino acid sequence. The results demonstrated that C280 and C283 are the SIRT3 S-glutathionylation sites. The results of experiments using ischemic intestines from clinical cases confirmed the relationship between GRX2 and SIRT3.

Innovation: This study demonstrates that GRX2 alleviates mitochondrial oxidative damage following II/R by reversing the S-glutathionylation of SIRT3.

Conclusion: GRX2 is an important protective factor against II/R injury, and GRX2-mediated deglutathionylation of SIRT3 alleviates II/R-induced mitochondrial injury and intestinal damage. Antioxid. Redox Signal. 45, 721-738.