Targets of a cytidine deaminase required for left-right axis in Xenopus

描述(由申请人提供)：基因组信息的表观遗传修饰是生物学中一个日益重要的领域。胞苷脱氨酶家族的RNA/DNA修饰酶与成人的重要过程有关，但与胚胎发育无关。研究人员在非洲爪哇胚胎基因组筛查中发现了胞苷脱氨酶XAPOBEC-2(非洲爪哇载脂蛋白B编辑催化亚基2，XA2)，以寻找受结节型转化生长因子-β信号调节的因子。在没有结节信号的情况下，不对称的内脏，如心脏和肠道，是随机定向的(随机的左右轴)。初步数据表明，非洲爪哇中的XA2和C2C12成肌细胞中的小鼠同系物A2抑制结节型转化生长因子-β信号转导。在非洲爪哇缺乏XA2的情况下，左右轴不对称是异常的，而C2C12细胞中A2的缺乏会降低肌肉分化。此应用程序的目标是确定与左右轴确定和肌肉分化相关的XA2/A2靶点。利用非洲爪哇和C2C12细胞中可用的生化(大量胚胎材料)、基因组(基因阵列)和分子(吗啉寡核苷酸，MO)工具，这一目标将在两个目标上完成：1.A2对转化生长因子-β信号的分子作用。研究人员将结合现有的功能丧失和功能获得的试剂来建立XA2和节点通路之间的上位关系。2.确定A2的目标。他将结合生化和基因组技术来检索和识别XA2和A2靶标。候选基因将被测试与蛋白质的直接生化相互作用，由其编辑活性引起的突变，以及对左右轴和肌肉分化的影响。 该项目将证实第一个RNA/DNA编辑参与信号转导和两个主要发育过程的案例，并将扩大我们对RNA/DNA编辑酶如何调节生物过程的理解。 PEOJECT简介：胞苷脱氨酶是一种RNA和DNA修饰酶，在人类病理学中越来越重要，从脂代谢及其并发症(动脉粥样硬化)到抗逆转录病毒(艾滋病毒和相关病毒)防御，以及抗体生成的缺陷。研究人员发现，APOBEC2是一种在脊椎动物中保守的胞苷脱氨酶，以前没有已知的功能，它是心脏、肠道、肝脏和胰腺等不对称内脏(左右不对称)正确定位所必需的，这表明了一种重要发育过程的新的分子机制。此外，APOBEC2刺激多能细胞系分化为肌肉纤维。许多先天性心脏缺陷是由左向右向缺陷引起的，退行性肌肉疾病是人类病理的重要组成部分。因此，理解左右不对称和肌肉分化的潜在分子机制与人类病理学有关。找到APOBEC2靶向的基因将大大提高我们对在人类病理学中日益重要的蛋白质家族的了解。

DESCRIPTION (Provided by Applicant): Epigenetic modification of genomic information is an increasingly important field in biology. RNA/DNA modifying enzymes of the cytidine deaminase family have been connected to important processes in adults, but not to embryonic development. The investigator found the cytidine deaminase XAPOBEC-2 (Xenopus apoB editing catalytic subunit 2, XA2) in a genomic screen for factors regulated by nodal-type TGF-¿ signaling in Xenopus laevis embryos. In the absence of nodal signaling asymmetric internal organs, such as the heart and gut, are randomly oriented (randomized left-right axis). Preliminary data indicate that XA2 in Xenopus and the mouse homologue A2 in C2C12 myoblasts inhibit nodal-type TGF-¿ signaling. In the absence of XA2 in Xenopus, left-right axis asymmetry is abnormal, and A2 absence in C2C12 cells reduces muscle differentiation. The goal of this application is to identify targets of XA2/A2 relevant for left-right axis determination and muscle differentiation. Taking advantage of the biochemical (large amounts of embryonic material), genomic (gene arrays), and molecular (morpholino oligonucleotides, MO) tools available in Xenopus and C2C12 cells, the goal will be completed in two aims: 1. molecular effects of A2 on TGF-¿ signaling. The investigator will combine existing loss- and gain-of-function reagents to establish the epistatic relation between XA2 and the nodal pathway. 2. identify targets of A2. He will combine biochemical and genomic techniques to retrieve and identify XA2 and A2 targets. Candidate genes will be tested for direct biochemical interaction with the protein, mutations induced by its editing activity, and effect on the left-right axis and muscle differentiation. This project will substantiate the first case of RNA/DNA editing involvement in signal transduction and two major developmental processes, and will expand our understanding of how RNA/DNA editing enzymes regulate biological processes. PEOJECT NARRATIVE: Cytidine deaminases are RNA and DNA modifying enzymes of increasing importance in human pathology, from lipid metabolism and its complications (atherosclerosis), to antiretroviral (HIV and related viruses) defense, and defects in the generation of antibodies. The investigator found that APOBEC2, a cytidine deaminase conserved in vertebrates with no previously known function, is required for correct orientation of asymmetric internal organs (left-right asymmetry), such as the heart, gut, liver, and pancreas, suggesting a novel molecular mechanism for an essential developmental process. In addition, APOBEC2 stimulates the differentiation of a multipotent cell line into muscle fibers. Many congenital heart defects are caused by defects in left-right orientation in humans, and degenerative muscle diseases are an important part of human pathology. Understanding the underlying molecular mechanisms of left-right asymmetry and muscle differentiation is therefore relevant for human pathology. Finding the genes targeted by APOBEC2 will significantly improve our knowledge of a family of proteins increasingly important in human pathology.