PDF(Pubmed)
Abstract：
Chicken embryos serve as an important model for investigating germ cells due to their ease of accessibility and manipulation within the egg. Understanding the development of germ cells is particularly crucial, as they are the only cell types capable of transmitting genetic information to the next generation. Therefore, gene expression regulation in germ cells is important for genomic function. Epigenetic programming is a crucial biological process for the regulation of gene expression without altering the genome sequence. Although epigenetic programming is evolutionarily conserved, several differences between chickens and mammals have been revealed. In this review, we compared the epigenetic regulation of germ cells in chickens and mammals (mainly mice as a representative species). In mammals, migrating primordial germ cells (precursors for germ cells [PGCs]) undergo global DNA demethylation and persist until sexual differentiation, while in chickens, DNA is demethylated until reaching the gonad but remethylated when sexually differentiated. Prospermatogonia is methylated at the onset of mitotic arrest in mammals, while DNA is demethylated at mitotic arrest in chickens. Furthermore, genomic imprinting and inactivation of sex chromosomes are differentially regulated through DNA methylation in chickens and mammals. Chickens and mammals exhibit different patterns of histone modifications during germ cell development, and non-coding RNA, which is not involved in PGC differentiation in mice, plays an important role in chicken PGC development. Additionally, several chicken-specific non-coding RNAs have been identified. In conclusion, we summarized current knowledge of epigenetic gene regulation of chicken germ cells, comparing that of mammals, and highlighted notable differences between them.
摘要：
鸡胚胎是研究生殖细胞的重要模型，因为它们易于在卵中获取和操作。了解生殖细胞的发育尤为重要,因为它们是唯一能够将遗传信息传递给下一代的细胞类型。因此,生殖细胞的基因表达调控对基因组功能具有重要意义。表观遗传编程是调节基因表达而不改变基因组序列的关键生物学过程。尽管表观遗传编程在进化上是保守的，已经揭示了鸡和哺乳动物之间的一些差异。在这次审查中,我们比较了鸡和哺乳动物(以小鼠为代表种)生殖细胞的表观遗传调控。在哺乳动物中,迁移原始生殖细胞（生殖细胞的前体[PGCs]）经历全球DNA去甲基化并持续到性分化，在鸡身上，DNA去甲基化直到到达性腺，但在性分化时再甲基化。精原细胞在哺乳动物的有丝分裂停滞开始时被甲基化，而DNA在鸡的有丝分裂停止时被去甲基化。此外，鸡和哺乳动物的基因组印记和性染色体失活是通过DNA甲基化进行差异调节的。鸡和哺乳动物在生殖细胞发育过程中表现出不同的组蛋白修饰模式，和非编码RNA，它不参与小鼠的PGC分化，在鸡PGC的发育中起着重要作用。此外,已经鉴定了几种鸡特异性非编码RNA。总之,我们总结了鸡生殖细胞表观遗传基因调控的最新知识，比较哺乳动物，并强调了它们之间的显著差异。
