Purpose: Aging is a complex biological process that begins at the cellular level, disrupting energy homeostasis. This study investigated the role of Sirt3, major mitochondrial deacetylase involved in metabolic pathways, in sex-dependent changes in energy homeostasis during aging in kidney of Sirt3 WT and KO mice.

Methods: Enzymatic activity, lipid peroxidation, protein carbonylation with Western blot and metabolomic analyses were performed to assess physiological and metabolic parameters

Results: Higher Sirt3 expression in male WT mice leads to increased vulnerability to its deficiency, as reflected in the shorter lifespan of male KO mice. This is further supported by distinct metabolomic clustering in male KO mice, highlighting significant metabolic disruptions. Male-specific declines in metabolites such as creatine, phosphorylcholine, trimethylamine-N-oxide, and L-carnitine, along with reduced trifunctional multienzyme complex subunit β (HADHB) expression, point to impaired fatty acid metabolism and mitochondrial dysfunction.

Conclusions: The findings emphasize the sex-specific function of Sirt3 in regulating mitochondrial activity, energy metabolism, and oxidative stress in the murine kidney, with male mice exhibiting a greater reliance on Sirt3 for metabolic stability.

Ageing is a complex process characterised by the gradual deterioration of physiological functions and increased susceptibility to various age-related diseases. Mitochondrial dysfunction is an important factor contributing to ageing. Sirtuin 3 (Sirt3), a mitochondrial protein essential for energy homeostasis, plays a critical role in maintaining mitochondrial function, as loss of Sirt3 reduces energy and impairs cellular repair, which accelerates ageing. The aim of this study was to investigate the role of Sirt3 in male and female mouse embryonic fibroblasts (MEF) exposed to etoposide-induced DNA damage. We employed state-of-the-art genetic, molecular, and imaging technologies as well as metabolomic analyses to provide insights into the molecular mechanisms underlying these responses. We found that the loss of Sirt3 affected metabolic responses differently depending on sex: while male MEF showed minimal damage, possibly due to earlier stress adaptation, female MEF lacking Sirt3 were more vulnerable, suggesting that Sirt3 plays a critical role in enhancing their ability to withstand such challenges. By focusing on Sirt3 and sex-specific signalling pathways it modulates, this study has a potential for developing new strategies to combat diseases associated with DNA damage — a cornerstone of the ageing process.