Evidence for expression of estrogen receptor cofactor messenger ribonucleic acid in the ovary and uterus of domesticated animals (sheep, cow and pig)

Expression levels of estrogen receptor cofactors (coactivators or corepress ors) in specific tissue compartments and cells are thought to influence the expression of estrogen responsive genes and thereby influence overall horm onal responsiveness of target tissues. To date, the presence of cofactors h as been reported in tissues from humans, rats and mice. We analyzed the pre sence and distribution of messenger ribonucleic acids (mRNAs) encoding seve ral transcriptional cofactors in the ovary and uterus of three domestic ani mal species, the sheep, cow and pig. Northern analysis for cofactors SRC-I, GRIP1, RAC3, p300, RIP140, and SPA showed expression in ovaries from all t hree species. In addition, lower expression of SRC-1, GRIP1, RAC3, p300, an d RIP140 mRNAs was observed during the luteal phase (day 10-12 of the estro us cycle) than at estrus (day 0): however, SPA transcript levels remained u nchanged. We then examined expression of mRNAs for changing (SRC-I, RIP140) and constitutively expressed (SPA) cofactors in ovine ovaries; SRC-I and R IP140 transcripts in corpus luteum were lower compared to the surrounding o varian tissue. SPA mRNA expression, however, was similar in corpus luteum a nd surrounding tissues. To determine which ovarian cell types express SRC-1 , RIP140, and SPA, in situ hybridization was performed on sheep ovaries. Si lver grains corresponding to these cofactors were seen in ovarian granulosa , theca and stromal cells, but appeared to be most abundant in the granulos a cells. Expression of SRC-1 and RIP140 in corpus luteum, however, was redu ced compared to expression in follicular cells. Finally, we examined cofact or expression in ovine, bovine, and porcine uterus. Northern blot analysis for SRC-1, GRIP1, RAC3, p300, and RIP140 mRNAs showed higher expression in extracts of the endometrium compared to whole uterus. We provide the first evidence for the presence of estrogen receptor cofactor mRNAs in the ovary and uterus of three domestic animal species. We suggest that coactivators a re conserved among species and associated with hormonal responsiveness of r eproductive tract tissues in sheep, cow and pig. (C) 2001 Elsevier Science Inc. All rights reserved.