Jinno Y, Ikeda Y, Yun K, Maw M, Masuzaki H, Fukuda H, Inuzuka K, Fujishita A, Ohtani Y, Okimoto T
Department of Human Genetics, Nagasaki University School of Medicine, Japan.
Nat Genet. 1995 Jul;10(3):318-24. doi: 10.1038/ng0795-318.
We have found that the imprinted H19 gene can be expressed either biallelically or monoallelically in the developing human placentae. H19 biallelic expression is confined to the placenta until 10 weeks of gestation, after which it becomes exclusively maternal, and does not affect allele-specificity or levels of IGF2 expression. The promoter region of H19 is hypomethylated at all stages of placental development, while the 3' portion shows progressive methylation of the paternal allele with gestation. Our observations demonstrate that the establishment of functional H19 imprinting occurs during the early development of the placenta and provide an opportunity to understand the mechanism by which the H19 primary imprint is manifested in somatic cells.
我们发现，印记基因H19在发育中的人类胎盘中可以双等位基因表达或单等位基因表达。H19双等位基因表达在妊娠10周前仅限于胎盘，之后则完全为母源表达，且不影响等位基因特异性或IGF2表达水平。H19的启动子区域在胎盘发育的各个阶段均处于低甲基化状态，而其3'部分随着妊娠进展父源等位基因呈现渐进性甲基化。我们的观察结果表明，功能性H19印记的建立发生在胎盘早期发育过程中，并为了解H19原始印记在体细胞中得以体现的机制提供了契机。
