Pregnancy-associated genes contribute to antiluteolytic mechanisms in ovine coprus luteum

Ovine interferon-tau (IFNT) is released from the conceptus by Day 12 of pregnancy and disrupts pulsatile release of endometrial prostaglandin F2 alpha (PGF), thereby protecting the corpus luteum (CL). IFNT may also have endocrine action through inducing interferon stimulated genes (ISGs) in the CL. The hypothesis that gene expression differs in CL collected from pregnant (P) and non-pregnant (NP) ewes by Day 14 due to the lytic action of PGF during the estrous cycle or the presence of a conceptus was tested. RNA was isolated on Days 12 and 14 in NP or P ewes (n = 3 ewes/group) and analyzed using the Affymetrix bovine microarray (24,000 targets). Differential gene expression (>1.5 fold, P < 0.05) was confirmed using semi-quantitative real time PCR (RTPCR). Serum progesterone concentrations decreased (P < 0.05) from 1.7 ng/ml on Day 12 to 1.3 ng/ml by Day 14 in NP ewes suggesting initiation of luteolysis; and remained > 1.7 ng/ml in Day 12 and 14 P ewes indicating that the conceptus protected the CL from luteolysis. Early luteolysis from Day 12 to 14 NP was associated with differential expression of 683 genes, including SERPINE1 and THBS1. Presence of a conceptus from Day 12 to 14 also induced expression of 743 genes, i.e., ISGs (ISG15, MX1), PTX3, and IL-6 and stabilized expression of VEGF and LHR genes. In conclusion, pregnancy circumvents luteolytic pathways, and activates or stabilizes genes associated with interferon, chemokine, cell adhesion, cytoskeletal, angiogenic and epithelial to mesynchymal transition pathways in the CL.

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