136. PROGESTERONE RECEPTOR-REGULATED GENES IN THE PREOVULATORY OVARIAN FOLLICLE AND OVIDUCT

Abstract

Ovulation is a highly regulated and precisely timed reproductive process but the underlying molecular mechanisms are not well understood. Progesterone receptor (PGR) is a transcription factor highly yet transiently expressed in granulosa cells (GCs) of preovulatory follicles; has low expression in cumulus-oocyte-complexes (COCs); and is abundantly expressed in the oviduct. PR–/– mice validate its essential role in ovulation as they are anovulatory, despite normal growth and development of ovarian follicles and oocytes. Our aim was to use microarray to identify differentially expressed genes in GCs, COCs and oviducts from PR–/– and PR+/– mice, specifically genes potentially involved in oocyte release and transport. GCs, COCs and oviducts were collected from 21d-old mice (n = 5; 3 mice/replicate) at 8h post-hCG/44h post-eCG. Extracted RNA samples were hybridized to Affymetrix Mouse Gene 1.0 ST Arrays and post-experiment processing/analysis performed using Partek Genomics Suite. Gene ontology analysis was performed using Ingenuity Pathway Analysis (IPA). In GCs, 296 genes were differentially expressed (P < 0.05); 78% down-regulated in PR–/–. IPA identified genes involved in cancer migration/invasion, chemotaxis, and adhesion; the chemokine receptor Cxcr4, was >3-fold down-regulated in PR–/–. Proteases were also decreased; Adam8 (3.5-fold) and Adamts1 (2.6-fold) in PR–/–. In oviducts, 1003 genes were differentially expressed at P < 0.05 and 266 genes at P < 0.01; 93% were down-regulated in PR–/–. IPA identified genes involved in cell adhesion, movement/migration, invasion and chemotaxis as well as muscle contraction and vasoconstriction. The most highly down-regulated was Itga8 (>9-fold), one of 11 integrins, well known cellular adhesion receptors, differentially expressed. In COCs, 44 genes were differentially expressed (P < 0.05); 52% down-regulated in PR–/–. IPA identified 18 genes (41%) involved in cancer invasion/migration or adhesion. Thus, this study has identified novel gene targets for PGR regulation, which may have essential roles in the molecular control of oocyte release into the oviduct at ovulation.