Autoregulation of mouse histone deacetylase 1 expression

Transcriptional regulation by the repressor of estrogen receptor activity via recruitment of histone deacetylases

Histone acetyltransferases and deacetylases are recruited by transcription factors and adapter proteins to regulate specific subsets of target genes. We were interested in identifying interaction partners of histone deacetylase 1 (HDAC1) that might be involved in conferring target or substrate specificity. Using the yeast two-hybrid system, we isolated the repressor of estrogen receptor activity (REA) as a novel HDAC1-associated protein. We demonstrated the in vivo interaction of REA with HDAC1 and characterized the respective domains required for their interaction in vitro. In addition, we found that REA also associates with the class II histone deacetylase HDAC5. In luciferase reporter assays, REA decreased transcription, and this repression was sensitive to the deacetylase inhibitor trichostatin A. Finally, we showed that REA specifically interacts with the chicken ovalbumin upstream binding transcription factors and II. The nuclear receptor chicken ovalbumin upstream binding transcription factor I was found to cooperate with REA and histone deacetylases in the repression of target genes. We, therefore, propose a novel function for REA as a mediator of transcriptional repression by nuclear hormone receptors via recruitment of histone deacetylases.

Regulation of histone deacetylase activities

Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from lysine residues in both histone and non-histone proteins. They play a key role in the regulation of gene transcription and many other biological processes involving chromatin. Significantly, recent studies suggest that HDACs are critically involved in cell-cycle regulation, cell proliferation, differentiation, and in the development of human cancer. HDAC inhibitors currently are being exploited as potential anti-cancer agents. As expected for vital regulators of many cellular processes, the activities of HDACs are tightly controlled and precisely regulated by multiple mechanisms. The activities of most if not all HDACs are regulated by protein-protein interactions. In addition, many HDACs are regulated by post-translational modifications as well as by subcellular localization. Less studied, but perhaps equally important, is the regulation of some HDACs by control of expression, availability of cofactors, and by proteolytic processing. A complete understanding of how HDACs are regulated will contribute not only to our overall knowledge of chromatin structure and gene control, but will offer tremendous insight into approaches for developing therapeutic HDAC inhibitors with improved specificity.