Effects of vitrification on the imprinted gene Snrpn in neonatal placental tissue

Objective: To investigate the effects of vitrification on the expression of the imprinted gene Snrpn in neonatal placental tissue. Methods: Neonatal placental tissue was collected from women with natural pregnancy (control group) and from women in assisted reproductive technology (ART) pregnancy group, following fresh and vitrified embryo transfer (fresh group and vitrified group, respectively). Snrpn mRNA expression and SNRPN protein levels in placental tissue from these three groups were assessed by real-time reverse transcription polymerase chain reaction and Western blot, respectively. DNA methylation in the Snrpn promoter region was analyzed by bisulfite-pyrosequencing. Results: The expression of Snrpn mRNA and SNRPN protein was found to be higher in placental tissue from the fresh and vitrified ART groups, compared to the control group. There was no significant difference in SNRPN gene or protein expression between the fresh and vitrified groups. DNA methylation at the Snrpn promoter region was not significantly different between these three groups. Conclusions: Human ART may alter the transcriptional expression and protein levels of the imprinted gene Snrpn. However, compared to other ART methods, vitrification may not aggravate or reduce this effect. Moreover, the altered expression of Snrpn is likely not directly related to DNA methylation of the Snrpn promoter region. Key words: Assisted Reproductive Technology; Polymerase Chain Reaction; Snrpn; Vitrification; Western Blot