Aebp2 as an epigenetic regulator for neural crest cell

描述(申请人提供)：神经脊细胞以其迁移到脊椎动物发育中的胚胎中不同位置的能力而闻名。这种迁移是通过几条信号通路来调节的。在这些途径中，RET和EDNRB途径的突变通常表现为人类遗传病，如先天性巨结肠(HSCR)和瓦登堡综合征(WS)。根据我们的初步数据，进化上保守的锌指基因Aebp2(脂肪细胞增强器结合蛋白2)可能在神经脊细胞的迁移中发挥关键作用。Aebp2已被鉴定为控制果蝇卵中边缘细胞迁移过程的调节因子，也是一种与哺乳动物Polycomb Repression Complex 2(PRC2)共纯化的锌指蛋白。我们最近的研究一致地表明，Aebp2的S全基因组靶点中的很大一部分与已知的PcG靶点重叠，支持Aebp2可能参与靶向哺乳动物PrC2的观点。有趣的是，Aebp2主要表达于神经脊起源的细胞，如背根神经节和面部软骨和骨骼。此外，根据来自破坏Aebp2的突变小鼠系的结果，许多杂合子表现出一组在患有先天性巨结肠和Waardenburg综合征的人类患者中常见的表型，例如巨结肠和色素减退。这些表型提示Aebp2可能是神经脊细胞迁移和发育所必需的。鉴于这些观察，我们假设Aebp2可能是通过PcG介导的机制对神经脊细胞进行表观遗传调节。在目前的提议中，我们将以以下目标来检验这一假说：Aim1将进一步表征从Aebp2杂合子观察到的表型的分子基础，AIM2将测试PRC2介导的机制在WS和HSCR发病机制中的潜在参与，最后Aim3将产生Aebp2基因的条件KO等位基因，以进一步描述Aebp2在神经脊细胞迁移中的作用。从这些实验中获得的信息将有助于解开Aebp2在体内的作用，特别是它在神经脊细胞迁移中的潜在作用。这一信息也应该为人类神经病变、先天性巨结肠和瓦登堡综合征的发病机制提供一个基于表观遗传学的新范式。

DESCRIPTION (provided by applicant): The neural crest cell is well known for its migration capability to various locations within the developing embryo of vertebrates. This migration is mediated through several signaling pathways. Among these pathways, mutations in the RET and EDNRB pathways often manifest as human genetic diseases, such as Hirschsprung's disease (HSCR) and Waardenburg syndrome (WS). According to our preliminary data, one evolutionarily conserved zinc finger gene, Aebp2 (Adipocyte Enhancer Binding protein 2), may play a critical role in the migration of the neural crest cell. Aebp2 previously has been identifie as a regulator controlling the migration process of the border cell in Drosophila eggs, and also as a zinc finger protein co-purified with the mammalian Polycomb Repression Complex 2 (PRC2). Consistently, our recent studies reveal that a large fraction of Aebp2's genome-wide target loci overlap with the known PcG target loci, supporting the idea that Aebp2 is likely involved in targeting the mammalian PRC2. Interestingly, Aebp2 is mainly expressed within cells of neural crest origin, such as dorsal root ganglia, and facial cartilages and bones. Furthermore, according to the results derived from a mutant mouse line disrupting Aebp2, many heterozygotes display a set of phenotypes that are usually seen in human patients with Hirschsprung's disease and Waardenburg syndrome, for example megacolon and hypopigmentation. These phenotypes suggest that Aebp2 may be required for the migration and development of the neural crest cell. Given these observations, we hypothesie that Aebp2 may be an epigenetic regulator for the neural crest cell through PcG-mediated mechanisms. In the current proposal, we will test this hypothesis with the following aims: Aim1 will further characterize the molecular basis of the phenotypes observed from the Aebp2 heterozygotes, Aim2 will test potential involvement of the PRC2-mediated mechanism in the pathogenesis of WS and HSCR, and finally Aim3 will generate a conditional KO allele of the Aebp2 locus to further delineate Aebp2 roles in neural crest cell migration. The information derived from these experiments will be helpful in unraveling the in vivo roles of Aebp2 with a special focus on its potential roles in neural crest cell migration. This information should also provide a new epigenetic-based paradigm for the pathogenesis of the human neurocristopathies, Hirschsprung's disease and Waardenburg syndrome.