SIRT3-FOXO3a Isoforms Forge Nuclear–Mitochondrial Links to Combat Sepsis-Induced Cardiomyopathy Oxidative Stress in Mice

Abstract

Aims:

Sepsis-induced cardiomyopathy (SIC) is a serious complication of sepsis. The relationship between SIC and protein acetylation, particularly the balance between acetylation and deacetylation in cardiomyocyte subcellular structures, as well as how nuclear–mitochondrial coordination maintains standard antioxidant stress capacity, remains unclear. This study focused on exploring the nuclear–mitochondrial regulatory mechanisms formed by the interplay of Sirtuin 3 (SIRT3) and Forkhead box O3a (FOXO3a).

Results:

In vivo, SIC markers increased significantly in wild-type CLP (Cecal Ligation and Puncture) mice at 72 h (CLP72h) but were partially reversed in CLP72h+oeSIRT3 mice. CLP72h mice exhibited significantly reduced mitochondrial area, aspect ratio, and mtDNA copy number. Echocardiography revealed significantly impaired cardiac function. Western blotting showed significantly decreased nuclear and mitochondrial long-form SIRT3, nuclear long-form and mitochondrial short-form FOXO3a, and mitochondrial superoxide dismutase 2 (SOD2), with significantly increased acetylation in CLP72h mice. In vitro, oeSIRT3 preserved nuclear FOXO3a localization and mitochondrial membrane potential, with CLP72h+oeSIRT3 mice showing significantly reduced oxidative stress. The long form of SIRT3 plays a crucial deacetylation role in SIC and influences SOD2 partially through FOXO3a.

Innovation:

This study explored the roles of different SIRT3 and FOXO3a isoforms in combating oxidative stress in SIC through dynamic nucleus-mitochondrial regulation.

Conclusion:

This study underscores the critical role of the SIRT3-FOXO3a axis in enhancing mitochondrial antioxidant capacity through a nuclear–mitochondrial network during SIC, offering new insights into molecular mechanisms and potential therapeutic strategies for SIC. Antioxid. Redox Signal. 43, 805–818.