Dynamic CpG and non-CpG methylation of the Peg1/Mest gene in the mouse oocyte and preimplantation embryo.
In somatic tissues, the CpG island of the imprinted Peg1/Mest gene is methylated on the maternal allele. We have examined the methylation of CpG and non-CpG sites of this differentially methylated CpG island in freshly ovulated oocytes, in vitro aged oocytes, and preimplantation embryos. The CpG methylation pattern was heterogeneous in freshly ovulated oocytes, despite the fact that they all were arrested in metaphase II. After short in vitro culture, Peg1/Mest became hypermethylated, whereas prolonged in vitro culture resulted in demethylation in a fraction of oocytes. Non-CpG methylation also occurred in a stage-specific manner. On alleles that were fully methylated at CpG sites, this modification was found, and it became reduced in two-cell stage embryos and blastocysts. These observations suggest that the process of establishment of the methylation imprint at this locus is more dynamic than previously thought.
Imamura
Takuya
T
INSERM E367, Epigénétique, Pathologies et Développement, Institut Jacques Monod, Paris, France.
Kerjean
Antoine
A
Heams
Thomas
T
Kupiec
Jean-Jacques
JJ
Thenevin
Catherine
C
Pàldi
Andràs
A
D000818:Animals; D001483:Base Sequence; D001755:Blastocyst / Q000378:metabolism*; D016922:Cellular Senescence; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000378:metabolism; D018899:CpG Islands; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D066298:In Vitro Techniques; D008677:Metaphase; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D011506:Proteins / Q000235:genetics*
D011506:Proteins; C103637:mesoderm specific transcript protein; D004247:DNA