Fig. 3. Thyroid hormone-induced CAII activation induces cofactor exchange at the HS2 enhancer region. (A) Northern blot showing activation of CAII transcription in HD3-V3 cells treated with T3 (300 nM), AZAdC (500 nM) or both. Band 4.1 served as a control. (B) DNA-affinity pull-down experiment with oligomerized VRE oligonucleotides in extracts from HD3-V3 cells either untreated or stimulated for 24 h with 300 nM T3. Western blot analysis shows the association/release of indicated corepressor/coactivator subunits with respect to c-/v-ErbA bound to the VRE. (C) HS2 enhancer ChIP experiment with soluble chromatin isolated from untreated and T3-treated (24 h, 300 nM) HD3-V3 cells using antibodies directed against the indicated proteins. HS2 PCR-signals were quantified as in Figure 1D. (D) as (C), but primer sets that amplify the promoter region were used to quantify the recovered DNA.