GCN5L1-Mediated Lysine Acetylation Regulates Mitochondrial Bioenergetics and Redox Homeostasis in the Aged Heart

Precise control of mitochondrial electron transport is essential to maintain mitochondrial coupling and efficiency in ATP production. Furthermore, disruptions to ETC complex function can drive increased oxidant production, resulting in oxidative damage to the mitochondrion and bioenergetic inefficiency. This is highly relevant in the aging heart, as increased cardiac oxidative stress and mitochondrial dysfunction(definition) are hallmarks of age-related cardiovascular disease. Lysine acetylation has recently been characterized as a novel regulator of mitochondrial metabolic and bioenergetic function in the aging heart. In the present study, we investigated how lysine acetylation regulates oxidant production and redox milieu through mitochondrial acetyltransferase GCN5L1. Using a cardiac-specific GCN5L1 knockout mouse model, we observed that age-associated lipid peroxidation and semiquinone radicals were decreased with GCN5L1 KO. RNA sequencing analysis identified mitochondrial bioenergetic and respiratory pathways revolving around the respiratory chain to be enriched in the old KO group. Further, we showed the old KO group to exhibit reduced acetylation of ETC complex and antioxidant proteins, improved ETC complex and antioxidant protein activity. Overall, GCN5L1 regulates redox homeostasis in the aged heart by regulating mitochondrial ETC complex activity, oxidative stress, and mitochondrial bioenergetics. These findings identify GCN5L1 and acetylation as potential therapeutic targets in aging and age-related diseases.