Diploid parthenogenetic embryos adopt a maternal-type methylation pattern on both sets of maternal chromosomes.
Epigenetic modifications are closely associated with embryo developmental potential. One of the epigenetic modifications thought to be involved in genomic imprinting is DNA methylation. Here we show that the maternally imprinted genes Snrpn and Peg1/Mest were nearly unmethylated or heavily methylated, respectively, in their differentially methylated regions (DMRs) at the two-cell stage in parthenogenetic embryos. However, both genes were gradually de novo methylated, with almost complete methylation of all CpG sites by the morula stage in parthenogenetic embryos. Unexpectedly, another maternally imprinted gene, Peg3, showed distinct dynamics of methylation during preimplantation development of diploid parthenogenetic embryos. Peg3 showed seemingly normal methylation patterns at the two-cell and morula stages, but was also strongly de novo methylated in parthenogenetic blastocysts. In contrast, the paternally imprinted genes H19 and Rasgrf1 showed complete unmethylation of their DMRs at the morula stage in parthenogenetic embryos. These results indicate that diploid parthenogenetic embryos adopt a maternal-type methylation pattern on both sets of maternal chromosomes and that the aberrantly homogeneous status of methylation imprints may partially account for developmental failure.
Liu
Jing-He
JH
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
Zhu
Jia-Qiao
JQ
Liang
Xing-Wei
XW
Yin
Shen
S
Ola
Safiriyu Idowu
SI
Hou
Yi
Y
Chen
Da-Yuan
DY
Schatten
Heide
H
Sun
Qing-Yuan
QY
D000818:Animals; D001324:Autoantigens / Q000235:genetics; D002875:Chromosomes; D019175:DNA Methylation; D004171:Diploidy; D004622:Embryo, Mammalian; D005260:Female; D018392:Genomic Imprinting; D051741:Kruppel-Like Transcription Factors; D008297:Male; D051379:Mice; D010312:Parthenogenesis; D011506:Proteins; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics; D020666:ras-GRF1; D055517:snRNP Core Proteins
D001324:Autoantigens; D051741:Kruppel-Like Transcription Factors; C097901:Peg3 protein, mouse; D011506:Proteins; C513037:Rasgrf1 protein, mouse; D017411:Ribonucleoproteins, Small Nuclear; C103637:mesoderm specific transcript protein; D020666:ras-GRF1; D055517:snRNP Core Proteins