Half-lives of aspirin-mediated lysine acetylations

Aspirin, or acetylsalicylic acid is widely used to control pain, inflammation and fever. An important property of aspirin is its ability to acetylate multiple cellular proteins with some pharmacological functions explicable by the irreversible acetylation of cyclooxygenases at active site serine residues. We have used a labeled form of aspirin, aspirin-d3 to acetylate proteins in cultured human cells, and unambiguously identified over 12000 sites of acetylation, using acetylated lysine peptide enrichment combined with mass-spectrometry-based proteomics. Aspirin increases lysine acetylation occupancy of the majority of detected endogenous sites, but leaves almost unchanged a small group that are already highly acetylated. We show that cells are remarkably tolerant of this acetylation insult unless endogenous deacetylases are inhibited. This work raises the possibility that rather than single protein effects, some of the clinical features of aspirin may be the consequence of multiple concurrent protein modifications, and that combining aspirin with lysine deacetylase inhibitors may have important medical implications.