Thompson E M, Legouy E, Christians E, Renard J P
Unité de Biologie du Développement, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Development. 1995 Oct;121(10):3425-37. doi: 10.1242/dev.121.10.3425.
In the widely studied model organisms, Drosophila and Xenopus, early embryogenesis involves an extended series of nuclear divisions prior to activation of the zygotic genome. The mammalian embryo differs in that the early cleavage phase is already characterized by regulated cell cycles with specific zygotic gene expression. In the mouse, where major activation of the zygotic genome occurs at the 2-cell stage, the HSP70.1 gene is among the earliest genes to be expressed. We investigated the developmentally regulated expression of this gene during the preimplantation period, using a luciferase transgene, with or without flanking scaffold attachment regions (SARs). Cleavage stage-specific modifications in expression profiles were examined in terms of histone H4 acetylation status, topoisomerase II activity, and the localisation of HMG-I/Y, a nuclear protein with known affinity for the AT-tracts of SARs. We demonstrate that HSP70.1-associated transcription factors are not limiting, and that instead, there is a progressive maturation of chromatin structure that is directly involved in HSP70.1 regulation during early mouse development.
在广泛研究的模式生物果蝇和非洲爪蟾中，早期胚胎发生在合子基因组激活之前涉及一系列连续的核分裂。哺乳动物胚胎的不同之处在于，早期卵裂阶段已经以具有特定合子基因表达的受调控细胞周期为特征。在小鼠中，合子基因组的主要激活发生在二细胞阶段，HSP70.1基因是最早表达的基因之一。我们使用带有或不带有侧翼支架附着区域（SARs）的荧光素酶转基因，研究了该基因在植入前阶段的发育调控表达。根据组蛋白H4乙酰化状态、拓扑异构酶II活性以及HMG-I/Y（一种对SARs的AT序列具有已知亲和力的核蛋白）的定位，研究了卵裂阶段特异性的表达谱修饰。我们证明，与HSP70.1相关的转录因子不是限制因素，相反，染色质结构在小鼠早期发育过程中直接参与HSP70.1调控，且存在渐进性成熟。
