Transcription nuclear receptor coregulators

A Large Number of Nuclear Receptor Coregulators Also Participate in Regulating Transcription... 

NUCLEAR RECEPTOR COREGULATORS AND EPIGENETIC REGULATION OF GENE TRANSCRIPTION... 

Figure 43-11. The hormone response transcription unit. The hormone response transcription unit is an assembly of DNA elements and bound proteins that interact, through protein-protein interactions, with a number of coactivator or corepressor molecules. An essential component is the hormone response element which binds the ligand (A)-bound receptor (R). Also Important are the accessory factor elements (AFEs) with bound transcription factors. More than two dozen of these accessory factors (AFs), which are often members of the nuclear receptor superfamily, have been linked to hormone effects on transcription. The AFs can interact with each other, with the liganded nuclear receptors, or with coregulators. These components communicate with the basal transcription complex through a coregulator complex that can consist of one or more members of the pi 60, corepressor, mediator-related, or CBP/p300 families (see Table 43-6).

Chromatin remodeling, transcription factor modification by various enzyme activities, and the communication between the nuclear receptors and the basal transcription apparatus are accomplished by protein-protein interactions with one or more of a class of coregulator molecules. The number of these coregulator molecules now exceeds 100, not counting species variations and splice variants. The first of these to be described was the CREB-binding protein, CBP. CBP, through an amino terminal domain, binds to phosphorylated serine 137 of CREB and mediates transactivation in response to cAMP. It thus is described as a coactivator. CBP and... 

Another large family of coregulator proteins remodel chromatin, modify other transcription factots, and bridge the nuclear receptors to the basal ttanscription apparatus. 

Glass, C. and Rosenfeld, M. The coregulator exchange in transcriptional functions of nuclear receptors. Genes Dev. 14 121-141,2000. 

Rosenfeld MG, Glass CK (2001) Coregulator codes of transcriptional regulation by nuclear receptors. J Biol Chem 276 36865-36868... 

The interaction of glucocorticoid receptors with GREs or other transcription factors is facilitated or inhibited by several families of proteins called steroid receptor coregulators, divided into coactivators and corepressors. The coregulators do this by serving as bridges between the receptors and other nuclear proteins and by expressing enzymatic activities such as histone acetylase or deacetylase, which alter the... 

---