| Research Abstract |
Steroid hormones exert their actons through cognate nuclear receptors, which act ligand-inducible transcriptional factors. For this ligand-induced transactivation, ligand-bound nuclear receptors, nuclear receptors depend on ligand binding, but it Is induced only by agonist, but not antgonist. In the present study, we searched novel coactivators for nuclear receptors for estrogen, androgen mineralcorticoid, vitamin D by biochemical approaches and yeast two-hybrid systen, and found several candidate cDNAs. Especially, we found that Smad3, TGF-beta signal inducers, acts as coactivator for VDR.Moreover, we developed an assay system based on the interactions of coactivators with nuclear receptors in yeast to evaluate agonistic/antagonistid activity of related compounds.
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