Interaction of nuclear receptor zinc finger DNA binding domains with histone deacetylase

A direct interaction between the nuclear receptor TR2 and histone deacetylases (HDACs) 3 and 4 is mediated by the DNA binding domain (DBD) of TR2. To test if this interaction is common to members of the nuclear receptor family, the Cys2-Cys2 type zinc finger (ZF) DBDs were subcloned from several nuclear receptors (mRARα, mRXRβ, mTR2, mTR4, RAR, mPPARδ, and mPPARγ2). Using GST pull-downs, both HDACs 3 and 4 were found to interact directly with the core DBD from each receptor. The three-dimensional structure of the ZF domains was essential for this interaction as disruption by zinc chelation precluded interaction with HDACs. The results suggest that the ZFs of nuclear receptors provide a general interaction interface for HDACs 3 and 4. Functional significance of this interaction was demonstrated using ChIP assays where a truncated TR2 protein (lacking the LBD) recruited HDACs 3 and 4 to the target DNA causing demonstrable histone deacetylation. GST pull-downs and mammalian two-hybrid interaction tests were then used to define the interaction domains of HDAC3 with TR2. Both the N- and C-terminal portions of HDAC3 showed interaction with the TR2 DBD. Thus, multiple domains of HDAC3 form the interaction surface for the DBD of nuclear receptors.