Regulation of histone deacetylase 8 substrate specificity (768.14)

Lysine acetylation, catalyzed by lysine acetyltransferases (KATs or HATs), is an important post‐translational modification of proteins such as histones, transcription factors, nuclear regulators, and cytoplasmic proteins. The modification is reversible; hydrolysis is catalyzed by a group of enzymes called histone deacetylases (HDACs). Lysine deacetylation is important for regulating various cellular processes, and aberrant deacetylation is implicated in cancer. Histone deacetylase 8 (HDAC8) is one of the metal‐dependent HDACs, and initial studies identified Zn(II) as the catalytic metal ion in the active site. Recent in vitro studies have shown that HDAC8 is activated not only by Zn(II), but also by Co(II) and Fe(II). We propose that in vivo regulation of HDAC8 activity may be modulated by metal switching. Using pull‐downs of HDAC8 over‐expressed in tissue culture cells and mass spectrometry, we are developing methods to determine the in vivo metal ion cofactor(s) of HDAC8, and preliminary data indicates there is a mixture of iron and zinc present. We are also investigating the mechanism by which phosphorylation of Ser39 on HDAC8 regulates HDAC8 activity by exploring potential changes in substrate specificity compared to wild type HDAC8 using peptide libraries.Grant Funding Source: Supported by grants from the National Institutes of Health