Histone deacetylases: salesmen and customers in the post-translational modification market.

HDACs (histone deacetylases) are enzymes that remove the acetyl moiety from N-epsilon-acetylated lysine residues in histones and non-histone proteins. In recent years, it has turned out that HDACs themselves are also subject to post-translational modification. Such structural alterations can determine the stability, localization, activity and protein-protein interactions of HDACs. This subsequently affects the modification of their substrates and the co-ordination of cellular signalling networks. Intriguingly, physiologically relevant non-histone proteins are increasingly found to be deacetylated by HDACs, and aberrant deacetylase activity contributes to several severe human diseases. Targeting the catalytic activity of these enzymes and their post-translational modifications are therefore attractive targets for therapeutical intervention strategies. To achieve this ambitious goal, details on the molecular mechanisms regulating post-translational modifications of HDACs are required. This review summarizes aspects of the current knowledge on the biological role and enzymology of the phosphorylation, acetylation, ubiquitylation and sumoylation of HDACs.