Repression by Ikaros and Aiolos is mediated through histone deacetylase complexes

Here we show that the lymphoid lineage-determining factors Ikaros and Aiolo s can function as strong transcriptional repressors. This function is media ted through two repression domains and is dependent upon the promoter conte xt and cell type, Repression by Ikaros proteins correlates with hypo-acetyl ation of core histones at promoter sites and is relieved by histone deacety lase inhibitors. Consistent with these findings, Ikaros and its repression domains can interact in vivo and in vitro with the mSin3 family of co-repre ssors which bind to histone deacetylases. Based on these and our recent fin dings of associations between Ikaros and Mi-2-HDAC, we propose that Ikaros family members modulate gene expression during lymphocyte development by re cruiting distinct histone deacetylase complexes to specific promoters.