FIG. 6.
The dnTR retains corepressors at the T3 response genes even in the presence of T3 and prevents T3-induced histone acetylation at the target genes. Wild-type tadpoles (wt, lanes 1 and 2) or transgenic tadpoles carrying the GFP-TR fusion gene dnTR (Tg, lanes 3) were treated with (lanes 2 and 3) or without (lanes 1) 50 nM (for acetylated H4 [AcH4]) or 5 nM (for all others) T3 for 1 day. ChIP assay was carried out as in Fig. 5 except that different antibodies were used as indicated. Note that T3 induced the release of corepressors in wild-type animals but, in transgenic animals expressing dnTR, this release was inhibited significantly if not completely (the extent of the inhibition appeared to vary slightly in different tissues for the two genes but this does not affect the conclusion), and as a result, histone acetylation levels at the target genes in the transgenic animals were lower compared to wild-type animals even though both were treated with T3. The INPUT control shows the DNA level prior to immunoprecipitation with the antibodies.