#Sir2 reverb rar Activator

Here we focus on components of the co-repressor machinery that depend, at least in part, on the actions of histone deacetylases, discussing primarily the nuclear receptor co-repressor (N-CoR) and silencing mediator of retinoic and thyroid hormone receptors (SMRT)( Fig.

#Sir2 reverb rar Activator

Repressive factors use several distinct mechanisms, including competition with activator proteins for DNA binding, sequestration of such activators, interaction with the core transcriptional machinery, DNA methylation and recruitment of complexes that have histone deacetylase activity. Although activation of transcription has long been recognized as an essential component of gene regulation, the realization that repression of transcription also plays a fundamental role has been appreciated only recently. In eukaryotes, these proteins number in the thousands and include sequence-specific DNA-binding factors, the basal transcriptional machinary,chromatin-remodeling factors, enzymes responsible for covalent modifications of histones and other proteins and cofactors that bridge DNA-binding factors and enzymes. The essential nature of such control is highlighted by the large number of proteins devoted to regulation of transcription by RNA polymerase II. The regulation of gene expression by transcriptional control is required for many cellular events and for the proper development of an organism. Recently, the biological importance of these proteins has been revealed by studies of genetically engineered mice and human diseases such as acute promyelocytic leukemia (APL) and resistance to thyroid hormone(RTH). Both N-CoR and SMRT are important targets for cell signaling pathways, which influence their expression levels, subcellular localization and association with other proteins. This association with histone deacetylase activity provides an important component of the mechanism that allows DNA-binding proteins interacting with N-CoR or SMRT to repress transcription of specific target genes. The closely related co-repressor proteins N-CoR and SMRT, although originally identified on the basis of their ability to associate with and confer transcriptional repression through nuclear receptors, have been shown to be recruited to many classes of transcription factor and are in fact components of multiple protein complexes containing histone deacetylase proteins. Transcriptional repression, which plays a crucial role in diverse biological processes, is mediated in part by non-DNA-binding co-repressors.