Developmental regulation of nuclear domains

总结 在后生动物胚胎中，母体和合子因子合作建立基因调控域， 参与基因被协调调节的细胞核，这些区域被维持 在整个发展中。为了成功地建立结构域，转录因子必须有效地定位结构域。 适当的区域的核，执行正确的功能范围内的域，并有助于 在受精卵发育过程中主动维持该结构域。我们的总体目标是确定核武器 在整个发展过程中，各领域都受到管制。定义直接域定位的信号将使我们能够 进一步破译顺式调控密码：蛋白质如何与细胞中的同源序列相互作用， 分化与疾病 我们将使用果蝇组蛋白基因座来实现这一目标，这是一个由超过100个基因组成的高度重复区域。 100个串联基因阵列，吸引一般和独特的转录因子，形成组蛋白基因座 体（HLB）结构域。我们最近描述了组蛋白基因座cis 启动结构域形成的序列和转录因子，但转录因子如何合作， 建立和维护域没有很好地定义。此外，DNA序列不足以确定 转录因子在结构域中的功能。相反，因子必须整合多种信息源 序列外，包括基因组背景，染色质线索，如组蛋白标记，和三维 场所组织，以执行正确的上下文特定的功能。 捕获导致核结构域起始的步骤是具有挑战性的，原因有三个：1）许多关键步骤， 事件发生在非常早期的胚胎中，胚胎具有很少的细胞，因此具有很少的生物材料， 2）母体沉积的转录因子被装载到卵中并且难以耗尽;以及3） 在合子基因组活化之前不可能使用报告转基因。然而，通过使用 异位组蛋白基因阵列，它仍然是结构域形成的目标，我们可以操纵信号驻留在 导致转录因子募集的基因座。在我的新实验室里，我们正在使用这个系统， 广泛的遗传工具库在果蝇，和创造性的方法来克服这些 挑战和解决我们在胚胎发生过程中的核结构域形成的理解的重要差距。 我们将定义启动核结构域的表观遗传机制，并确定转录因子 整合多个级别的基因组信息以执行特定于域的功能。我们的工作意义重大 因为我们的观察将提供对其他重复区域的调节和组织的洞察， 如核糖体RNA基因，以及非基因区域如端粒和着丝粒。

SUMMARY In metazoan embryos, maternal and zygotic factors collaborate to establish gene regulatory domains, regions of the nucleus in which participating genes are coordinately regulated, and these domains are maintained throughout development. To successfully establish domains, transcription factors must effectively locate the appropriate region of the nucleus, perform the correct function within the context of the domain, and contribute to the active maintenance of the domain as the zygote develops. Our overall goal is to determine how nuclear domains are regulated throughout development. Defining the signals that direct domain targeting will allow us to further decipher the cis regulatory code: how proteins interact with cognate sequences in a cell, leading to differentiation and disease. We will pursue this goal using the Drosophila histone locus, a highly repetitive region composed of over 100 tandem gene arrays that attract both general and unique transcription factors, forming the histone locus body (HLB) domain. We recently described some of the earliest interactions between histone locus cis sequences and transcription factors that initiate domain formation, but how transcription factors collaborate to establish and maintain a domain is not well defined. In addition, DNA sequence is not sufficient to determine transcription factor function within a domain. Rather, factors must integrate multiple sources of information outside of sequence, including genomic context, chromatin cues such as histone marks, and three dimensional locus organization, to perform correct context-specific functions. It is challenging to capture the steps that lead to nuclear domain initiation for three reasons: 1) Many key events take place in the very early embryo which has few cells and therefore little biological material with which to work; 2) Maternally deposited transcription factors are loaded into the egg and are difficult to deplete; and 3) It is not possible to use reporter transgenes before activation of the zygotic genome. However, by using an ectopic histone gene array, which is still targeted for domain formation, we can manipulate signals residing in the locus that lead to transcription factor recruitment. In my new laboratory, we are using this system, the extensive repertoire of genetic tools in Drosophila melanogaster, and creative approaches to overcome these challenges and address important gaps in our understanding of nuclear domain formation during embryogenesis. We will define the epigenetic mechanisms that initiate nuclear domains and determine how transcription factors integrate multiple levels of genomic information to perform domain-specific functions. Our work is significant because our observations will provide insight into the regulation and organization of other repetitive regions, such as the ribosomal RNA genes, as well as for non-genic regions such as telomeres and centromeres.