Cloning and characterization of a novel human histone deacetylase, HDAC8

Histone deacetylases (HDACs) are a growing family of enzymes implicated in transcriptional regulation by affecting the acetylation state of core histo nes in the nucleus of cells. HDACs are known to have key roles in the regul ation of cell proliferation [Brehm, Miska, McCance, Reid, Bannister and Kou zarides (1998) Nature (London) 391, 597-600], and aberrant recruitment of a n HDAC complex has been shown to be a key step in the mechanism of cell tra nsformation in acute promyelocytic leukaemia [Grignani, De Matteis, Nervi, Tomassoni, Gelmetti, Cioce, Fanelli, Ruthardt, Ferrara, Zamir et al. (1998) Nature (London) 391, 815-818; Lin, Nagy, Inoue, Shao, Miller and Evans (19 98), Nature (London) 391, 811-814]. Here we present the complete nucleotide sequence of a cDNA clone, termed HDAC8, that encodes a protein product wit h similarity to the RPD3 class (I) of HDACs. The predicted 377-residue HDAC 8 product contains a shorter C-terminal extension relative to other members of its class. After expression in two cell systems, immunopurified HDAC8 i s shown to possess trichostatin A- and sodium butyrate-inhititable HDAC act ivity on histone H4 peptide substrates as well as on core histones. Express ion profiling reveals the expression of HDACs to various degrees in every t issue tested and also in several tumour lines. Mutation of two adjacent his tidine residues within the predicted active site severely decreases activit y, confirming these residues as important for HDAC8 enzyme activity. Finall y, linkage analysis after radiation hybrid mapping has localized HDAC8 to c hromosomal position Xq21.2-Xq21.3. These results confirm HDAC8 as a new mem ber of the HDAC family.