Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea.
Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea.
Poult Sci. 2024 Sep;103(9):103977. doi: 10.1016/j.psj.2024.103977. Epub 2024 Jun 18.
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.
鸡胚胎是研究生殖细胞的重要模型，因为它们在鸡蛋内易于获取和操作。了解生殖细胞的发育非常重要，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，生殖细胞中的基因表达调控对于基因组功能至关重要。表观遗传编程是调节基因表达而不改变基因组序列的重要生物学过程。尽管表观遗传编程在进化上是保守的，但已经揭示了鸡和哺乳动物之间的一些差异。在这篇综述中，我们比较了鸡和哺乳动物（主要以小鼠作为代表物种）生殖细胞的表观遗传调控。在哺乳动物中，迁移的原始生殖细胞（生殖细胞[PGC]的前体）经历全局 DNA 去甲基化，并持续到性分化，而在鸡中，DNA 去甲基化直到到达性腺，但在性分化时重新甲基化。在哺乳动物中，生殖细胞有丝分裂停滞时 prospermatogonia 被甲基化，而鸡中 DNA 在有丝分裂停滞时去甲基化。此外，鸡和哺乳动物通过 DNA 甲基化差异调节基因组印记和性染色体失活。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，并且在小鼠中不参与 PGC 分化的非编码 RNA 在鸡 PGC 发育中发挥重要作用。此外，还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现有知识，比较了哺乳动物的情况，并强调了它们之间的显著差异。
