| Scope and method of study. During the establishment of pregnancy in the pig a significant percentage of littermates fail to survive past Day 18 of gestation. Imperative biological processes in both the developing conceptus and uterine endometrium regulate attachment, implantation, and the prevention of luteolysis. Improvement in swine reproduction efficiency through reducing early embryonic mortality is achievable and will dramatically affect this important agriculture sector in the United States. Through the utilization of molecular techniques including; microarray hybridization, in situ hybridization, and quantitative reverse transcription polymerase chain reaction (QT-PCR), we sought to identify the molecular mechanisms that are associated with rapid trophoblastic elongation, endometrial response to estrogen stimulation and the roles of nuclear factor kappa B (NFkappaB) in regulating uterine receptivity and the prevention of luteolysis.; Findings and conclusions. The utilization of the Affymetrix GeneChipRTM Porcine Genome Array allowed the identification of over 1400 genes that are differentially expressed by the developing conceptus during Days 11 to 14 of gestation. The expression patterns for several of these genes; including angiomotin, B-cell linker and chemokine ligand 14, were analyzed through QT-PCR, confirming the array data. A 15 K cDNA arrayed identified uterine endometrial genes that are estrogen regulated and associated with estrogen induced implantation failure. In situ hybridization demonstrated estrogen disrupted expression of aldose reductase, secreted phosphoprotein 1, CD24 antigen, and neuromedin B was localized to endometrial luminal epithelium during failed conceptus attachment and implantation. DNA binding experiments coupled with gene expression profiling of NFkappaB related genes; receptor activator of NFkappaB, toll-like receptor 4, inhibitor of NFkappaB alpha and beta, and NFkappaB subunits, p50 and RelA, suggest NFkappaB activation during uterine receptivity and the instigation of luteolytic mechanisms during the estrous cycle. The regulation of NFkappaB activation is closely correlated to expression patterns of progesterone receptor and estrogen receptor alpha in the uterine luminal epithelium. Collectively, these three studies have each identified and characterized interrelated molecular mechanisms in both the developing conceptuses and uterine endometrium whose expression patterns provide insight into the molecular factors that are involved with the establishment of pregnancy in the pig. |
