Control of histone modifications

A role for histone modifications in transcription processes and the remodel ing of chromatin structure has been established. This review highlights the recent advances made in studies on histone acetyltransferases, histone dea cetylases, histone kinases, and protein phosphatases, as well as their role s in transcriptional activation and repression. Coactivators with histone a cetyltransferase activity stimulate transcription, whereas corepressors wit h histone deacetylase activity repress transcription. Families of histone a cetyltransferases and deacetylases have been identified. We have learned th at their substrates are not limited to histones but also include transcript ion factors and architectural proteins. Studies on the composition of multi protein complexes with histone acetyltransferase or histone deacetylase hav e revealed mechanisms by which these complexes are recruited to specific ge nomic sites that are transcriptionally active, silenced, or being repaired. A new and exciting development, presented in this review, is the role of s ignal transduction pathways in the phosphorylation of histone H3 and the ex pression of immediate-early genes. (C) 1999 Wiley-Liss, Inc.