Transcription factor p53 can regulate proliferation, apoptosis and secretory activity of luteinizing porcine ovarian granulosa cell cultured with and without ghrelin and FSH

Abstract

The aim of our in vitro experiments was to examine the role of transcription factor p53 in controlling the basic functions of ovarian cells and their response to hormonal treatments. Porcine ovarian granulosa cells, transfected and non-transfected with a gene construct encoding p53, were cultured with ghrelin and FSH (all at concentrations of 0, 1, 10, or 100 ng/ml). Accumulation of p53, of apoptosisrelated (MAP3K5) and proliferation-related (cyclin B1) substances was evaluated by immunocytochemistry. The secretion of progesterone (P 4 ), oxytocin (OT), prostaglandin F (PGF), and E (PGE) was measured by RIA. Transfection with the p53 gene construct promoted accumulation of this transcription factor within cells. It also stimulated the expression of a marker of apoptosis (MAP3K5). Over-expression of p53 resulted in reduced accumulation of a marker of proliferation (cyclin B1), P 4 , and PGF secretion and increased OT and PGE secretion. Ghrelin, when added alone, did not affect p53 or P 4 , but reduced MAP3K5 and increased PGF and PGE secretion. Over-expression of p53 reversed the effect of ghrelin on OT, caused it to be inhibitory to P 4 secretion, but did not modify its action on MAP3K5, PGF, or PGE. FSH promoted the accumulation of p53, MAP3K5, and cyclin B1; these effects were unaffected by p53 transfection. These multiple effects of the p53 gene construct on luteinizing granulosa cells, cultured with and without hormones 1) demonstrate the effects of ghrelin and FSH on porcine ovarian cell apoptosis and secretory activity, 2) confirm the involvement of p53 in promoting apoptosis and inhibiting P 4 secretion in these cells, 3) provide the first evidence that p53 suppress proliferation of ovarian cells, 4) provide the first evidence that p53 is involved in the control of ovarian peptide hormone (OT) and prostaglandin (PGF and PGE) secretion, and 5) suggest that p53 can modulate, but probably not mediate, the effects of ghrelin and FSH on the ovary. Reproduction (2008) 136 611-618

Involvement of the transcription factor STAT1 in the regulation of porcine ovarian granulosa cell functions treated and not treated with ghrelin

“…The stimulatory action on PGF and nonapeptide hormone secretion correspond generally with data obtained using cultured chicken (Sirotkin & Grossmann 2006) and porcine (Sirotkin et al 2008a) ovarian cells, but not with previous reports of the stimulatory action of ghrelin on P 4 and IGF1 release in rabbit ovarian cells (Sirotkin et al 2008b) and on lack of effect of ghrelin on P 4 release in porcine granulosa cells (Sirotkin et al 2008a). Therefore, ghrelin controls ovarian functions in a species-specific manner.…”

“…Therefore, ghrelin controls ovarian functions in a species-specific manner. Furthermore, comparison results of our previous (Sirotkin et al 2008a) and present studies suggest that some effects of ghrelin on porcine granulosa cells in a different series of experiments can be different. Such alterations in ghrelin action could be due to the initial state of ovarian cells affected by season, nutrition and other environmental factors.…”

“…Reporter plasmid pEGFP-N1 for enhanced green fluorescent protein (EGFP) and resistance to kanamycin was provided by Clontech. Plasmids were multiplied as previously described (Sirotkin et al 2008a(Sirotkin et al , 2008b). …”

“…Ghrelin can inhibit secretory activity (Barreiro & Tena-Sempere 2004, Tena-Sempere 2005, 2008 of rat testicular cells and proliferation of rat prostatic cells (Yeh et al 2005), and may be involved in the control of cell proliferation in ovarian and testicular tumours. Recently it was demonstrated that it can directly control the function of ovarian cells by stimulating proliferation; inhibiting apoptosis; promoting steroid hormone, insulin-like growth factor-I (IGF1) and vasotocin secretion (chicken, Sirotkin & Grossmann 2006;pig, Rak & Gregoraszczuk 2008); and stimulating prostaglandins F (PGF) and PGE (pig, Sirotkin et al 2008a), progesterone (P 4 ) and IGF1 (rabbit, Sirotkin et al 2008b) release.…”

Ο ρόλος της ghrelin στην έκκριση της προλακτίνης και των γοναδοτροφινών ορμονών σε γυναίκες

“…Σε καλλιέργεια ωχρινοποιηµένων κοκκωδών κυτάρων χοίρων, η γκρελίνη δεν επηρέασε την παραγωγή του p53 ή της προγεστερόνης, αλλά ελάττωσε την έκκριση της MAP3K5 και αύξησε την έκκριση των προσταγλανδινών F και E (Sirotkin et al, 2008b). Aπό την άλλη µεριά, η υπερέκφραση του p53 µετέτρεψε σε ανασταλτική τη δράση της γκρελίνης στην έκκριση της προγεστερόνης (Sirotkin et al, 2008b). H παρουσία της γκρελίνης και του υποδοχέα της έχει επίσης διαπιστωθεί και σε ορχικό ιστό του προβάτου .…”