Repression by Ikaros and Aiolos is mediated through histone deacetylase complexes.

Here we show that the lymphoid lineage-determining factors Ikaros and Aiolos can function as strong transcriptional repressors. This function is mediated through two repression domains and is dependent upon the promoter context and cell type. Repression by Ikaros proteins correlates with hypo-acetylation of core histones at promoter sites and is relieved by histone deacetylase inhibitors. Consistent with these findings, Ikaros and its repression domains can interact in vivo and in vitro with the mSin3 family of co-repressors which bind to histone deacetylases. Based on these and our recent findings of associations between Ikaros and Mi-2-HDAC, we propose that Ikaros family members modulate gene expression during lymphocyte development by recruiting distinct histone deacetylase complexes to specific promoters.