Characterization of Genes Differentially Expressed in Placenta of Yorkshire and Meishan Pigs During Pregnancy

The placental efficiency is one of the major determinants of litter size in pigs. We examined gene expression profiles of placenta from Meishan and Yorkshire pigs collected at days 26 and 50 of gestation. We found that the expression pattern of HPSE, an endoglycosidase that specifically degrades heparan sulfate, was significant different in Yorkshire and Meishan placentas on days 26, 50 and 95 of gestation by q-PCR, immunohistochemistry and in situ hybridization. During later gestation, the mRNA and protein levels were higher in placentas from Meishan compared to Yorkshire pigs. The HPSE mRNA was expressed by all the trophoblast and the protein was located at all the trophoblas cells in Meishan pigs during later gestation, while in Yorkshire pigs the HPSE mRNA and protein were only identified in trophoblast cells which were located at the bottom and side of the folds. In addition, we also found that the E-cadherin, â-Catenin and ZO1 were expressed by trophoblast cells located at the top of the placental folds in Yorkshire pigs, while in Meishan pigs all of the trophoblast cells didn't express these genes. Our findings suggested that the mechanisms of migration, invasion and proliferation of trophoblast cells were different between Yorkshire and Meishan pigs during later gestation.