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Although nonclassical estrogen actions initiated at the cell surface have been described in many tissues, the identities of the membrane estrogen receptors (mERs) mediating these actions remain unclear. Here we show that GPR30, an orphan receptor unrelated to nuclear estrogen receptors, has all the binding and signaling characteristics of a mER. A(More)
Progestin withdrawal is a crucial event for the onset of labor in many mammalian species. However, in humans the mechanism of a functional progestin withdrawal is unclear, because progestin concentrations do not drop in maternal plasma preceding labor. We report the presence of two novel functional membrane progestin receptors (mPRs), mPR␣ and mPR␤, in(More)
Progesterone's (P4) negative feedback actions in the female reproductive axis are exerted in part by suppression of hypothalamic GnRH release. Here we show that P4 can inhibit GnRH release by a mechanism independent of a nuclear P4 receptor (PR(A/B)). Injections of P4, but not vehicle, allopregnanolone, or dexamethasone, acutely suppressed LH levels in both(More)
Membrane progesterone receptors (mPRs) are novel G protein-coupled receptors belonging to the progestin and adipoQ receptor family (PAQR) that mediate a variety of rapid cell surface-initiated progesterone actions in the reproductive system involving activation of intracellular signaling pathways (i.e. nonclassical actions). The mPRs are highly expressed in(More)
The identities of the membrane receptors mediating the majority of rapid, cell surface-initiated, nongenomic (i.e. nonclassical) steroid actions described to date are unclear. Two novel 7-transmembrane spanning proteins, representing two distinct classes of steroid membrane receptors, membrane progestin receptor alpha (mPRalpha) and a membrane estrogen(More)
Recently, a unique family of membrane progestin receptors (mPRalpha, mPRbeta, and mPRgamma) was identified, which may be responsible for mediating rapid, nongenomic actions of progestins in a variety of target tissues. In this study, the mPRalpha and mPRbeta isoforms from zebrafish were shown to be rapidly and specifically activated by the(More)
We have previously demonstrated that both activin and its receptors are expressed in the zebrafish ovary, suggesting paracrine roles for activin in the ovarian functions. Activin significantly stimulated zebrafish oocyte maturation in vitro, and this effect could be blocked by follistatin, an activin-binding protein. Interestingly, follistatin also blocked(More)
Progestin hormones exert rapid, nongenomic actions on a variety of target tissues in fish. The induction of oocyte maturation and the progestin membrane receptor (mPR) that mediates this action of progestins have been well characterized in fishes. Progestins also act on Atlantic croaker spermatozoa via an mPR to rapidly increase sperm motility. Preliminary(More)
The recent molecular cloning of membrane receptors for progesterone (mPRs) has tremendous implications for understanding the multiple actions of the hormone in the nervous system. The three isoforms which have been cloned from several species, mPRalpha, mPRbeta and mPRgamma, have seven-transmembrane domains, are G protein-coupled and may thus account for(More)
The functional characteristics of membrane progesterone receptors (mPRs) have been investigated using recombinant mPR proteins over-expressed in MDA-MB-231 breast cancer cells. Although these cells do not express the full-length progesterone receptor (PR), it is not known whether they express N-terminally truncated PR isoforms which could possibly account(More)