ACSS2 acts as a lactyl-CoA synthetase and couples KAT2A to function as a lactyltransferase for histone lactylation and tumor immune evasion.

Lactyl-coenzyme A (CoA)-dependent histone lysine lactylation impacts gene expression and plays fundamental roles in biological processes. However, mammalian lactyl-CoA synthetases and their regulation of histone lactylation have not yet been identified. Here, we demonstrate that epidermal growth factor receptor (EGFR) activation induces extracellular signal-regulated kinase (ERK)-mediated S267 phosphorylation of acetyl-CoA synthetase 2 (ACSS2) and its subsequent nuclear translocation and complex formation with lysine acetyltransferase 2A (KAT2A). Importantly, ACSS2 functions as a bona fide lactyl-CoA synthetase and converts lactate to lactyl-CoA, which binds to KAT2A as demonstrated by a co-crystal structure analysis. Consequently, KAT2A acts as a lactyltransferase to lactylate histone H3, leading to the expression of Wnt/β-catenin, NF-κB, and PD-L1 and brain tumor growth and immune evasion. A combination treatment with an ACSS2-KAT2A interaction-blocking peptide and an anti-PD-1 antibody induces an additive tumor-inhibitory effect. These findings uncover ACSS2 and KAT2A as hitherto unidentified lactyl-CoA synthetase and lactyltransferase, respectively, and the significance of the ACSS2-KAT2A coupling in gene expression and tumor development.