Involvement of histone acetylation in ovarian steroid-induced decidualization of human endometrial stromal cells

Histone acetyltransferases and histone deacetylases (HDACs) determine the acetylation status of histones, regulating gene transcription. Decidualization is the progestin-induced differentiation of estrogen-primed endometrial stromal cells (ESCs), which is crucial for implantation and maintenance of pregnancy. We here show that trichostatin A (TSA), a specific HDAC inhibitor, enhances the up-regulation of decidualization markers such as insulin-like growth factor binding protein-1 (IGFBP-1) and prolactin in a dose-dependent manner that is directed by 17beta-estradiol (E-2) plus progesterone (P-4) in cultured ESCs, but not glandular cells, both isolated from human endometrium. Morphological changes resembling decidual transformation were also augmented by co-addition of TSA. Acid urea triton gel analysis and immunoblot using acetylated histone type-specific antibodies demonstrated that treatment with E-2 plus P-4 significantly increased the levels of acetylated H3 and H4 whose increment was augmented by co-treatment with TSA. Chromatin immunoprecipitation assay revealed that treatment with E-2 plus P-4 increased the amount of proximal progesterone-responsive region of IGFBP-1 promoter associated with acetylated H4, which was dramatically enhanced by co-addition of TSA. Taken together, our results suggest that histone acetylation is deeply involved in differentiation of human ESCs and that TSA has a potential as an enhancer of decidualization through promotion of progesterone action.