Silvia Pavlová, Dušan Vašícek, Ján Kotwica and Alexander V. Sirotkin
Protein p21, member of the Cip/Kip family of cyclin kinase inhibitors, is a physiological regulator of cell cycle, differentiation and apoptosis in various cell types. Its role in regulation of secretory activity of both non-ovarian and ovarian tissues is unknown. The aim of our in-vitro experiments was to examine possible involvement of p21 in regulation of porcine ovarian granulosa cells secretory activity. Monolayer of primary granulosa cells was transfected with plasmid vector encoding human p21 cDNA, and cultured with or without addition of follicle-stimulating hormone (FSH) or insulin-like growth factor I (IGF-I) (both at 0, 1, 10 or 100 ng/ml). Release of IGF-I, progesterone (P4), oxytocin (OT), prostaglandins E2 (PGE2) and F2? (PGF2?) was assayed by using RIA. We observed, that (1) p21 promoted the release of P4, OT, PGE2 and had no impact on IGF-I and PGF2? output, (2) FSH stimulated the release of IGF-I and P4, (3) IGF-I enhanced the release of OT, P4 and PGE2 , but it inhibited the release of PGF2?, (4) overexpression of 21 was able to modify the effects of IGF-I, but not of FSH. Our observations (1) demonstrate for a first time the involvement of p21 in regulation of hormones release P4, OT and PGE2 by ovarian granulosa cells, (2) confirm the regulation of porcine ovarian hormone release by FSH and IGF-I and (3) suggest, that p21 is not a mediator of FSH action on porcine ovarian P4 and IGF-I; involvement of p21 in mediating IGF-I action on some porcine ovarian hormones is not to be excluded, but it requires further confirmation.