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

The aim of our in vitro experiments was to study the role of the transcription factor and the hormone ghrelin in controlling porcine ovarian function. The effects of treatment with ghrelin (0, 1, 10, 100 ng/ml), transfection-induced overexpression of transcription factor and their combination on apoptosis (expression of apoptosis-related peptides caspase-3, BAX and anti-apoptotic peptide BCL2), proliferation (expression of proliferating cell nuclear antigene PCNA, proliferation-associated protein kinase MAPK/ERK1,2) and release of the hormones progesterone (P(4)), prostaglandin F (PGF) and oxytocin (OXT) in cultured porcine ovarian granulosa cells was evaluated using RIA, immunocytochemistry and SDS-PAGE-western immunoblotting. It was found that ghrelin, when given alone, increased the expression of proliferation-associated PCNA and MAPK/ERK1,2, decreased the accumulation of apoptosis-related substances caspase-3, BAX, BCL2, decreased P(4), and increased PGF and OXT release. Ghrelin tended to promote accumulation of duanyu18131 in both control and transfected cells, although in transfected cells ghrelin at 1 ng/ml decreased duanyu18131 accumulation. Transfection of porcine granulosa cells by a gene construct encoding duanyu18131 promoted the expression of duanyu18131 and apoptosis-related-BAX but the expression of BCL2 did not, and decreased the accumulation of proliferation-associated MAPK/ERK1,2 but not that of PCNA. It also promoted PGF and OXT but not P(4) release. Overexpression of duanyu18131 reversed the effect of ghrelin on duanyu18131, PCNA, PGF, OXT (from stimulatory to inhibitory), BCL2, P(4) (from inhibitory to stimulatory), prevented ghrelin effect on caspase-3 and BAX, but did not affect ghrelin's effect on MAPK/ERK1,2 expression. These results suggest that ghrelin directly affects porcine ovarian cells function - stimulates proliferation, inhibits apoptosis and affects secretory activity. Furthermore, they demonstrated the involvement of the transcription factor duanyu18131 in controlling these functions, the promotion of some markers of apoptosis (BAX), inhibition of some markers of proliferation (MAPK/ERK1,2) and stimulation of PGF release. Finally, the obtained data failed to demonstrate that duanyu18131 is involved in mediating the action of ghrelin on ovarian cell functions.

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