Cell-Specific PRC1 Accessory Proteins and the Regulation of Mammalian Neurodevelopment

哺乳动物胚胎发育是一个单一的幼稚细胞被扩增并连续特化的过程，以产生成年身体的所有功能细胞类型。这一复杂的过程由蛋白质控制，蛋白质与调控的DNA序列结合，建立适当的基因表达的时间和空间模式。其中一个蛋白质效应器家族形成了被称为多梳抑制复合体(PRCs)的多个亚单位组件，它通过化学和物理修饰DNA的包装形式染色质来阻止基因的表达。在发育中的大脑中，随着祖细胞的增殖、迁移和特化，细胞状态会发生变化，而原癌细胞已被证明在这些步骤中起着重要作用。因此，在这种情况下，PRC功能的丧失会导致细胞和结构的异常。韦弗综合征是一种以认知障碍为特征的疾病，通常是大脑过度生长，由PRC功能丧失引起。此外，阻断PRC活性的突变发生在大多数弥漫性固有桥脑胶质瘤(DIPG)病例中，在这些病例中，它们促进肿瘤的形成。原癌基因还需要调节细胞的增殖、特化和保护，防止成年大脑中的神经退化。然而，缺乏对原癌基因如何调节神经发育基因表达模式的理解，阻碍了对这些细胞和结构异常的机械性解释。填补这一知识空白不仅是理解大脑发育的分子基础的关键，也是确定发育性大脑疾病的潜在缺陷的关键。为此，在神经发育过程中确定PRC功能和靶向的分子力学是很重要的。我的主要目标是：1)。确定在神经发育过程中PRC复合体成分改变的程度和功能重要性。2)。识别和操纵直接作用于或与染色质修饰协同作用的蛋白质，以在神经发育过程中将原癌细胞招募到其目标基因。为了达到这些目标，我将利用人工分化和原代培养的神经前体细胞(NPC)，结合高通量染色质状态分析、PRC结合染色质的蛋白质组成的定量分析、基因组工程和合成蛋白质靶向方法。完全了解PRC功能障碍引起的脑部疾病的分子基础将是建立有效和安全的治疗方法、预后和诊断测试以及为临床支持提供信息的关键一步。

Mammalian embryonic development is the process whereby a single naïve cell is expanded, and serially specialised, to produce all of the functional cell types of the adult body. This intricate process is governed by proteins, which bind to regulatory DNA sequences and establish the appropriate temporal and spatial patterns of gene expression. One such family of protein effectors form multi-subunit-assemblies termed polycomb repressive complexes (PRCs), which function to block gene expression by chemically and physically modifying chromatin - the packaged form of DNA. In the developing brain, changes in cell state occur as progenitor cells proliferate, migrate and specialise, and PRCs have been shown to be important for these steps. Consequently, loss of PRC function in this context leads to cellular and structural abnormalities. Weaver syndrome, a disorder characterised by cognitive impairment and often brain overgrowth, is caused by the loss of PRC function. Moreover, mutations that block PRC activity occur in the majority of cases of diffuse intrinsic pontine glioma (DIPG) in which they promote tumour formation. PRCs are also required for the regulation of cell proliferation, specialisation and protection against neurodegeneration in the adult brain. Mechanistic interpretation of these cellular and structural abnormalities, however, is hindered by the lack of understanding of how PRCs regulate neurodevelopmental gene expression patterns. Filling this knowledge gap is key to understanding not only the molecular basis of brain development, but also in determining the underlying deficits in developmental brain disorders. To this end, it is important to determine the molecular mechanics of PRC function and targeting during neurodevelopment. My key aims are: 1). Determine the extent and functional importance of alterations in PRC complex composition during neurodevelopment. 2). Identify and manipulate proteins which act either directly, or in collaboration with chromatin modifications, to recruit PRCs to their target genes during neurodevelopment. To address these aims I will utilise artificially differentiated and primary cultured neural progenitor cells (NPCs) in conjunction with high-throughput analysis of chromatin state, quantitative analysis of protein composition of PRC bound chromatin, genome-engineering and synthetic protein targeting approaches. A complete understanding of the molecular basis of disorders of the brain which arise from PRC dysfunction will be critical as a step towards establishing effective and safe therapeutic approaches, prognostic and diagnostic tests and to inform clinical support.