Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM U964, Université de Strasbourg, Illkirch, France.
Curr Top Dev Biol. 2013;104:1-45. doi: 10.1016/B978-0-12-416027-9.00001-2.
Early embryonic development in mammals is characterized by major changes in the components of the chromatin and its remodeling. The embryonic chromatin and the nuclear organization in the mouse preimplantation embryo display particular features that are dramatically different from somatic cells. These include the highly specific organization of the pericentromeric heterochromatin within the nucleus and the suggested lack of conventional heterochromatin. We postulate that the plasticity of the cells in the early embryo relies on the distinctive heterochromatin features that prevail during early embryogenesis. Here, we review some of these features and discuss recent findings on the mechanisms driving heterochromatin formation after fertilization, in particular, the emerging role of RNA as a regulator of heterochromatic loci also in mammals. Finally, we believe that there are at least three major avenues that should be addressed in the coming years: (i) Is heterochromatin a driving force in development? (ii) Does it have a role in lineage allocation? (iii) How can heterochromatin "regulate" epigenetic reprogramming?
哺乳动物的早期胚胎发育以染色质及其重塑成分的重大变化为特征。小鼠植入前胚胎中的胚胎染色质和核组织显示出与体细胞明显不同的特殊特征。这些特征包括核内着丝粒异染色质的高度特异性组织以及缺乏常规异染色质的建议。我们假设早期胚胎中细胞的可塑性依赖于早期胚胎发生过程中普遍存在的独特异染色质特征。在这里，我们回顾了其中的一些特征，并讨论了最近关于受精后异染色质形成机制的发现，特别是 RNA 作为哺乳动物中异染色质位点调节剂的新兴作用。最后，我们认为在未来几年至少应该解决三个主要问题：(i) 异染色质是发育的驱动力吗？(ii) 它在谱系分配中起作用吗？(iii) 异染色质如何“调节”表观遗传重编程？
