Lysine lactylation improves boar sperm energy metabolism and quality by enhancing aldolase C enzyme activity.

Sperm quality is a critical determinant of sow reproductive efficiency. As transcriptionally silent terminally differentiated cells, mature spermatozoa rely substantially on post-translational modifications (PTMs) to maintain functionality. Lysine lactylation (Kla), an emerging PTM driven by the metabolic substrate lactate, plays important roles in gene expression and metabolic regulation. However, its function in sperm has not yet been fully elucidated. This study investigated the distribution, function, and regulatory mechanisms of Kla in Duroc boar sperm. Kla was found to be widely distributed in the sperm head and tail, with its level showing a significant positive correlation with sperm motility. Moreover, elevated Kla levels enhanced sperm kinematic parameters, ATP content, mitochondrial membrane potential, and DNA integrity, with concomitant improvement in redox homeostasis. These improvements were reversed by sodium oxalate treatment. Mechanistically, Kla levels were modulated by enzymes including P300, AARS1 and Sirtuins, with sodium lactate acting as an acyl donor. Notably, proteomic analysis identified 212 putative Kla-targeted proteins enriched primarily in metabolic pathways including glycolysis and oxidative phosphorylation. Importantly, Kla modification of aldolase C (ALDOC) enhanced its enzymatic activity, thereby promoting sperm energy metabolism and functional competence. This study reveals a novel mechanism whereby Kla maintains porcine sperm quality by regulating ALDOC enzyme activity, providing a theoretical foundation for developing Kla-targeted semen preservation strategies.