Expression, Regulation, and Function of Progesterone Receptors in Bovine Cumulus Oocyte Complexes During In Vitro Maturation1

Abstract

Progesterone (P4) exerts its effects by binding to specific genomic (nPR-A/B) and non-genomic (mPRalpha/beta, PGRMC1/2) receptors. P4 has a role in the regulation of the ovulatory cycle, but its participation in oocyte maturation in mammals has not yet been clarified. Therefore, the aim of the present study was to characterize the protein expression of P4 receptors (PRs) in bovine oocytes and cumulus cells during in vitro maturation (IVM) and to study the effect of P4 and its receptors on oocyte developmental competence. Cumulus-oocyte complexes (COCs) were subjected to IVM, in vitro fertilization, and in vitro culture. IVM was performed for 24 h in the presence or absence of P4, luteinizing hormone (LH), follicle-stimulating hormone (FSH), trilostane, promegestone (R5020), mifepristone (RU 486), or antibodies against mPRalpha or mPRbeta. Protein expression of PRs was studied by Western blotting and immunofluorescence. The results demonstrate the presence of both genomic and nongenomic PRs in bovine COCs. The dynamic changes observed in the protein expression of PRs following IVM or in response to supplementation with LH, FSH, or P4 suggest an important role during bovine oocyte maturation. Inhibition of P4 synthesis by cumulus cells or blocking of nPR and mPR alpha activity produced a decrease in bovine embryo development, indicating that P4 intracellular signaling is mediated by its interaction with nuclear and membrane PRs and is important for oocyte developmental competence.

Heat stress effects on the cumulus cells surrounding the bovine oocyte during maturation: altered matrix metallopeptidase 9 and progesterone production

“…Heat-induced increases in the production of progesterone attest to the notion that the cumulus cells originating from the heat-stressed oocytes are functionally different from their non-heat-stressed counterparts. Because of the importance of these two cumulus-derived components (Regassa et al 2011) in the developmental competence of the oocyte (Dubois et al 2000, Silva & Knight 2000, Robert et al 2001, Yamashita et al 2003, Lee et al 2005, Aparicio et al 2011, collectively these findings support the notion for some of the negative consequences of heat stress on the cumulus-oocyte complex are mediated through the cumulus. During IVM, MMP9 is expressed exclusively by the cumulus surrounding the oocyte (Regassa et al 2011).…”

PGRMC1 participates in late events of bovine granulosa cells mitosis and oocyte meiosis

“…4,43,44 The observation that AG205 was more effective on DOs than COCs confirms PGRMC1s specific role within the oocyte. AG205 is a small aromatic compound that acts as a PGRMC1 ligand.…”

Three-step in vitro maturation culture of bovine oocytes imitating temporal changes of estradiol-17<i>β</i> and progesterone concentrations in preovulatory follicular fluid

“…Although neither anterior pituitary hormones nor growth factors were considered in the present three-step IVM culture system of bovine oocytes, both culture systems showed effectiveness of sequential stimulation of steroid hormones during IVM. Various concentrations of P 4 (50-5000 ng mL −1 ) were added to bovine IVM medium (Silva and Knight, 2000;Aparicio et al, 2011;Syoji et al, 2014). IVM culture of bovine oocytes with 50 or 100 ng mL −1 P 4 did not affect development to the blastocyst (Aparicio et al, 2011), while that with 94 ng mL −1 P 4 decreased the blastocyst formation rate (Silva and Knight, 2000).…”

“…P 4 was added to the IVM medium for bovine oocytes at a concentration of 50-5000 ng mL −1 , and various results were reported on embryo production (Silva and Knight, 2000;Aparicio et al, 2011;Syoji et al, 2014). Concentration of P 4 in the IVM medium was fixed during the culture except with Syoji et al (2014), and E 2 and P 4 concentrations in preovulatory follicular fluid were not considered for medium preparation in the previous studies.…”