Crosstalk of steroid receptors and pERK in endometrial stromal cells.

SARAGUETA, PATRICIA; VALLEJO, GRISELDA; BALLARE, CECILIA; BEATO, MIGUEL

Florence, Italy

Congreso; 13th World Congress of Gynecological Endocrinology (ISGE); 2008

International Society of Gynecological Endocrinology

Decidualization is governed by ovarian steroid hormones and by embryonic signals. To date there is no in vitro system available for the molecular dissection of this transdifferentiation process. Proliferation of UIII rat endometrial stromal cells in response to progestins requires active progesterone receptor (PR) and estrogen receptor beta (ERbeta) and is mediated by a rapid and transient activation of Erk1/2 and Akt signaling. The optimal R5020 concentration for the proliferative response and the activation of the signaling cascades is between 10 and 100pm, both effects are inhibited by antagonists of either PR or ER. UIII cells are negative for ERalpha and have low levels of ERbeta and PR located mainly in the cytoplasm. A fraction of endogenous PR and ERbeta form a complex as demonstrated by co-immunoprecipitation. Neither progestins nor estradiol transactivate the corresponding transfected reporter genes, suggesting that the endogenous levels of PR and ERbeta are insufficient for transcriptional activation. Cyclin D1 (CCND1) mRNA, one of the genes involved in progestin-dependent cell proliferation, increase after 45 min of R5020 treatment. To define the global network of gene expression involved in progestin-dependent proliferation we analyzed the transcriptome using rat oligonucleotide microarrays (Agilent). Statistical analysis in cells treated for 45 min with R5020 shows 56 up-regulated genes, including two early immediate genes, JunD and Cyr61, and 146 down-regulated genes, including three repressors, CDKn1b p27KIP1 , Gfi 1 and Sox 15, as validated by real time PCR.  Pretreatments with steroid receptor antagonists, a PDK1 inhibitor, or a MEK inhibitor show that short-term progestin induction of target genes depends on crosstalk between PR, ERbeta and at least two different cytoplasmic kinase pathways.