Disruption of imprinted gene expression and DNA methylation status in porcine parthenogenetic fetuses and placentas

• Maternally expressed genes were over-expressed in porcine PA samples.
• Paternally expressed genes were significantly reduced in porcine PA samples.
• Maintained methylation status of PRE-1 and Satellite in PA fetuses and placentas
• Abnormal XIST and aberrant XCI may contribute to failed PA fetal development.

Parthenogenetically activated oocytes cannot develop to term in mammals due to the lack of paternal gene expression and failed X chromosome inactivation (XCI). To further characterize porcine parthenogenesis, the expression of 18 imprinted genes was compared between parthenogenetic (PA) and normally fertilized embryos (Con) using quantitative real-time PCR (qRT-PCR). The results revealed that maternally expressed genes were over-expressed, whereas paternally expressed genes were significantly reduced in PA fetuses and placentas. The results of bisulfite sequencing PCR (BSP) demonstrated that PRE-1 and Satellite were hypermethylated in both Con and PA fetuses and placentas, while XIST DMRs were hypomethylated only in PA samples. Taken together, these results suggest that the aberrant methylation profile of XIST DMRs and abnormal imprinted gene expression may be responsible for developmental failure and impaired growth in porcine parthenogenesis.