Timing of establishment of paternal methylation imprints in the mouse.
Imprinted genes are characterized by predominant expression from one parental allele and differential DNA methylation. Few imprinted genes have been found to acquire a methylation mark in the male germ line, however, and only one of these, H19, has been studied in detail. We examined methylation of the Rasgrf1 and Gtl2 differentially methylated regions (DMR) to determine whether methylation is erased in male germ cells at e12.5 and when the paternal allele acquires methylation. We also compared their methylation dynamics with those of H19 and the maternally methylated gene Snrpn. Our results show that methylation is erased on Rasgrf1, H19, and Snrpn at e12.5, but that Gtl2 retains substantial methylation at this stage. Erasure of methylation marks on Gtl2 appears to occur later in female germ cells to give the unmethylated profile seen in mature MII oocytes. In the male germ line, de novo methylation of Rasgrf1, Gtl2, and H19 occurs in parallel between e12.5 and e17.5, but the DMR are not completely methylated until the mature sperm stage, suggesting a methylation dynamic different from that of IAP, L1, and minor satellite sequences, which have been shown to become fully methylated by e17.5 in male germ cells. This study also indicates important differences between different imprinted DMR in timing and extent of methylation in the germ cells.
Li
Jing-Yu
JY
Laboratory for Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
Lees-Murdock
Diane J
DJ
Xu
Guo-Liang
GL
Walsh
Colum P
CP
D000483:Alleles; D000818:Animals; D019175:DNA Methylation; D004622:Embryo, Mammalian / Q000166:cytology; D005260:Female; D005718:Gametogenesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting; D005854:Germ Cells / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D009865:Oocytes / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011506:Proteins / Q000235:genetics; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics; D013094:Spermatozoa / Q000502:physiology*; D013997:Time Factors; D020666:ras-GRF1 / Q000235:genetics
C094335:H19 long non-coding RNA; C422882:MEG3 non-coding RNA, mouse; D011506:Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D017411:Ribonucleoproteins, Small Nuclear; D020666:ras-GRF1