Expression And Function Of NPM1 In Mouse Ovary During Follicular Development And Corpus Luteum Formation

NPM1(Nucleophosmin) is a multifunctional protein. NPM1 participates in the ribosome biogenesis; It maintains genetic stability through the regulation of centrosome duplication; It constantly shuttles between the nucleus and cytoplasm; It has function as molecular chaperone; It is involved in cellular activities related to both proliferation and growth suppression pathways.In this study, we used in situ hybridization to examine the expression of NPM1 in mouse ovary during sexual maturation, follicular development induced by PMSG, ovulation and corpus luteum formation induced by PMSG/hCG. We found that during sexual maturation, from born to 40 days after birth, NPM1mRNA expressed in granulosa cells of folliculars at every stage. NPM1mRNA expressed in granulosa cells of primordial folliculars and primary folliculars, the expression of NPM1 in granulosa cells was enhanced in secondry folliculars and antral folliculars. In mature folliculars, NPM1 expressed highly in cumulus cells, and decreased in granulosa cells. During follicular development induced by PMSG,the expression of NPM1 in granulosa cells was up-regulated after 6 hours of PMSG injection and achieve summit 12 hours later, granulosa cells proliferated at this time. The expression of NPM1 declined significantly 36 hours and 48 hours after PMSG injection. We injected hCG 48 hours after PMSG injection to induce ovulation, 4 hours and 8 hours later, high level NPM1mRNA was found in cumulus cells when GVBD and cumulus expansion occurred before ovulation. 16 hours and 18 hours later, a weak signal was detected in granulosa cells after ovulation. 48 hours after PMSG injection and two days and three days after hCG treatment, there was a high level of NPM1 expression in newly formed corpus luteum.In vitro,we cultured mice primary granulosa cells, treated with different concentrations of NPM1 specific inhibitor NSC348884(0μM,0.5μM,1μM,2μM) for 24 hours, NPM1,StAR and P450sccmRNA were determinated by RT-PCR. The results showed that with the concentrations of NSC348884 increased, the expression of P450sccmRNA was declined, however, the expression of StARmRNA had no significant changing tendency, suggest that NPM1 may stimulate steroidogenic through interaction with P450scc.Our data suggest that NPM1 may play a role in granulose cell proliferation during follicular development , corpus luteum formation and stimulate steroidogenic.