Crotonylation of ACAT1 K181 contributes to radioresistance by impacting lactate metabolism.

Ionizing radiation (IR)-induced alterations in glucose metabolism are closely associated with radioresistance, yet the underlying mechanisms remain incompletely understood. Here, we identify a post-translational modification axis in which IR induces general control non-repressible protein 5 (GCN5/KAT2A)-mediated crotonylation of acetyl-CoA acetyltransferase 1 (ACAT1) at lysine 181 (K181), thereby enhancing ACAT1 activity and promoting increased acetylation of pyruvate dehydrogenase E1 subunit alpha (PDHA1) along with its phosphorylation at S293.These changes led to inhibition of PDHA1, impaired pyruvate metabolism, and increased lactate accumulation. Functional studies demonstrated that ACAT1 K181R (a decrotonylation-mimicking mutant) increased radiosensitivity and significantly attenuated IR-induced lactate production. Collectively, these findings reveal an unrecognized mechanism by which radiotherapy reprograms cellular metabolism through the GCN5-ACAT1-PDHA1 axis, linking ACAT1 crotonylation to altered pyruvate metabolism, enhanced lactate production, and subsequent radioresistance. These findings suggest that targeting ACAT1 K181 crotonylation represents a potential therapeutic strategy to improve tumor radiosensitivity.