Overexpression of Pde4d in rat granulosa cells inhibits maturation and atresia of antral follicles to induce polycystic ovary.

Background: Follicle dysplasia can cause polycystic ovary syndrome, which can lead to anovulatory infertility. This study explored gene(s) that may contribute to polycystic ovary syndrome.

Methods: Three animal models of polycystic ovary syndrome were created by treating 3-week-old rats respectively with estradiol valerate, testosterone propionate, or constant illumination for 8 weeks. Granulosa cells from the three disease groups and from healthy controls were transcriptionally profiled to identify differentially expressed genes. The phosphodiesterase-4d (Pde4d) was screened as the most promising candidate pathogenic gene. The Pde4d was overexpressed in rats via intrabursal infection with recombinant lentivirus to see the effect of Pde4d on ovarian morphology. The potential roles of the candidate gene and interactors of the encoded protein were explored using polymerase chain reaction, western blotting, transfection and co-immunoprecipitation.

Results: All three rat models of polycystic ovary syndrome showed polycystic ovary phenotype. Seven promising candidate genes were obtained by transcriptomics and verifications. Pde4d was further investigated because it could trigger downstream signaling pathways. The Pde4d overexpression in rat ovary induced cystic follicles. It inhibited follicle maturation through a mechanism involving inhibition of cAMP-PKA-CREB signaling. The Pde4d also inhibited phosphorylation of c-Jun N-terminal kinase to reduce apoptosis in the ovary, through a mechanism involving interaction of its poly-proline domain with the protein POSH.

Conclusion: Upregulation of Pde4d may contribute to polycystic ovary syndrome by impeding follicle maturation and preventing apoptotic atresia.