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

哺乳动物胚胎发育是一个单独的naïve细胞被扩展，并连续特化，以产生成人身体的所有功能细胞类型的过程。这个复杂的过程是由蛋白质控制的，蛋白质结合调控DNA序列并建立适当的时间和空间基因表达模式。一个这样的蛋白质效应家族形成了称为多梳抑制复合物（PRCs）的多亚基组装体，其功能是通过化学和物理修饰染色质（DNA的包装形式）来阻断基因表达。在发育中的大脑中，随着祖细胞增殖、迁移和特化，细胞状态发生变化，而prc已被证明对这些步骤很重要。因此，在这种情况下，PRC功能的丧失会导致细胞和结构异常。韦弗综合征，一种以认知障碍和大脑过度生长为特征的疾病，是由PRC功能丧失引起的。此外，阻断PRC活性的突变发生在大多数弥漫性内禀脑桥胶质瘤（DIPG）病例中，它们促进肿瘤形成。在成人大脑中，也需要prc来调节细胞增殖、特化和防止神经退行性变。然而，由于缺乏对prc如何调节神经发育基因表达模式的理解，这些细胞和结构异常的机制解释受到阻碍。填补这一知识空白不仅是理解大脑发育分子基础的关键，也是确定发育性大脑疾病潜在缺陷的关键。为此，确定PRC在神经发育过程中的功能和靶向的分子机制是很重要的。我的主要目标是：1)。确定神经发育过程中PRC复合物组成改变的程度和功能重要性。2）. 鉴定并操纵在神经发育过程中直接或与染色质修饰合作将prc招募到其靶基因的蛋白质。为了实现这些目标，我将利用人工分化和原代培养的神经祖细胞（npc），结合染色质状态的高通量分析，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。全面了解由PRC功能障碍引起的脑障碍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.