Role of protein methylation in chromatin remodeling and transcriptional regulation

Recent findings suggest that lysine and arginine-specific methylation of hi stones may cooperate with other types of post-translational histone modific ation to regulate chromatin structure and gene transcription. Proteins that methylate histones on arginine residues can collaborate with other coactiv ators to enhance the activity of specific transcriptional activators such a s nuclear receptors, Lysine methylation of histones is associated with tran scriptionally active nuclei, regulates other types of histone modifications , and is necessary for proper mitotic cell divisions. The fact that some tr anscription factors and proteins involved in RNA processing can also be met hylated suggests that protein methylation may also contribute in other ways to regulation of transcription and post-transcriptional steps in gene regu lation. In future work, it will be important to develop methods for evaluat ing the precise roles of protein methylation in the regulation of native ge nes in physiological settings, e.g. by using chromatin immunoprecipitation assays, differentiating cell culture systems, and genetically altered cells and animals. It will also be important to isolate additional protein methy ltransferases by molecular cloning and to characterize new methyltransferas e substrates, the regulation of methyltransferase activities, and the roles of new methyltransferases and substrates.