Mammalian histonedeacetylase 1: Interacting proteins and target promoters

Reversible histone acetylation plays an important role for chromatin structure and gene expression. The acetylation state of core histones is controlled by histone acetyltransferases and histone deacetylases. We have previously identified and cloned mouse histone deacetylase 1 as a growth factor inducible gene in T cells (Bartl et al. (1997), Mol. Cell. Biol. 8:5033-5043). The enzyme can repress transcription of particular genes when recruited by specific transcription factors to the corresponding promoters. The affinity of HDACl -interacting proteins for specific DNA motifs within these promoters determines the cellular targets for repression via histone deacetylation. Thus HDAC1- recruiting proteins are the key players in this type of gene regulation. Here we intend to identify and characterize novel HDAC 1-associated factors by genetic and biochemical approaches. In preliminary experiments we have already isolated some candidate genes. Firstly, we will screen for additional HDAC1-interacting proteins by the yeast two-hybrid system and by co-immunoprecipitation from extracts of mammalian cells. Secondly, we will characterize the interaction between the histone deacetylase and the binding partners and the biological function of the respective association. Recently we have generated a panel of acetyl-specific antibodies directed against each of the four target lysine residues of histone H4 (Taplick et al. (1998) FEBS Letters 436:349-52). Using this set of specific antisera we will investigate the acetylation state of nucleosomes within specific target promoters. In this way we would be able to directly link the recruitment of HDAC1 by specific transcription factors to local changes in the chromatin structure of target promoters. This project should help to clarify the role of histone deacetylase 1 in the regulation of gene expression in mammalian cells.