The paternal methylation imprint of the mouse H19 locus is acquired in the gonocyte stage during foetal testis development.
BACKGROUND
Germline-specific differential DNA methylation that persists through fertilization and embryonic development is thought to be the 'imprint' distinguishing the parental alleles of imprinted genes. If such methylation is to work as the imprinting mechanism, however, it has to be reprogrammed following each passage through the germline. Previous studies on maternally methylated genes have shown that their methylation imprints are first erased in primordial germ cells (PGCs) and then re-established during oocyte growth.


RESULTS
We have examined the timing of the reprogramming of the paternal methylation imprint of the mouse H19 gene during germ cell development. In both male and female PGCs, the paternal allele is partially methylated whereas the maternal allele is unmethylated. This partial methylation is completely erased in the female germline by entry into meiosis, establishing the oocyte methylation pattern. In the male germline, both alleles become methylated, mainly during the gonocyte stage, establishing the sperm methylation pattern.


CONCLUSIONS
The paternal methylation imprint of H19 is established in the male germline and erased in the female germline at specific developmental stages. The identification of the timings of the methylation and demethylation should help to identify and characterize the biochemical basis of the reprogramming of imprinting.
Ueda
T
T
Research Laboratory for Molecular Genetics, Niigata University, Niigata 951-8510, Japan.
Abe
K
K
Miura
A
A
Yuzuriha
M
M
Zubair
M
M
Noguchi
M
M
Niwa
K
K
Kawase
Y
Y
Kono
T
T
Matsuda
Y
Y
Fujimoto
H
H
Shibata
H
H
Hayashizaki
Y
Y
Sasaki
H
H
D000818:Animals; D019175:DNA Methylation; D005260:Female; D018392:Genomic Imprinting; D008297:Male; D051379:Mice; D008957:Models, Genetic; D009124:Muscle Proteins / Q000235:genetics*; D018807:Polymorphism, Single-Stranded Conformational; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D017422:Sequence Analysis, DNA; D012737:Sex Factors; D013447:Sulfites; D013737:Testis / Q000196:embryology*
C094335:H19 long non-coding RNA; D009124:Muscle Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D013447:Sulfites; C042345:hydrogen sulfite