Project 6: Regulation and Function of Extended 3' UTR Transcripts in the Nervous System

项目总结/摘要 神经系统中3 ′ UTR基因的转录调控及其功能 在不同的生物体中，超过50%的基因经历交替切割和聚腺苷酸化（阿帕）， 产生多种3 ′ UTR mRNA同种型。最近，成千上万的新的扩展的3 'UTR已经被 鉴定为优先在苍蝇、小鼠和人的神经系统中表达。这样一个无处不在的， 细胞特异性事件可能对神经系统产生广泛的生理相关后果 发育、维持和疾病。然而，到目前为止，很少有扩展的3 ′ UTR的功能角色 被识别。长期目标是揭示这些延伸的3 'UTR同种型在细胞中的功能。 神经系统，并阐明其生物发生和生物活性的机制。重点是一套 在轴突导向中扮演既定角色的基因。十多个基因在轴突导向中发挥作用 表达短和延长的3 ′ UTR亚型，表明阿帕是这个关键的重要调节因子。 神经发育事件其中一些基因与人类疾病直接相关。比如说， 钙调蛋白基因的突变与人类的多种心脏缺陷有关。调查延长3 ' 为了增强UTR功能，采用CRISPR基因组编辑来特异性地删除果蝇中的这些同种型。这 已经建立了一种方法，初步工作已经发现，延长的3 ′ UTR的损伤 在保持短的3 ′ UTR同种型完整的同时，可以损害神经系统发育。在Aim 1中， 方法扩展到CAM，果蝇钙调素基因。在目标2中，染色质修饰 对延长的3 ′ UTR的生物发生的影响。这是在目前关于该机制的工作的基础上进行的 ELAV通过其调控3 ′ UTR延伸。总的来说，这项工作将使阿帕成为一个至关重要的 控制轴突导向的多基因机制。

PROJECT SUMMARY/ABSTRACT Regulation and Function of Extended 3´ UTR Transcripts in the Nervous System More than 50% of genes in diverse organisms undergo Alternative Cleavage and PolyAdenylation (APA) to generate multiple 3´ UTR mRNA isoforms. Thousands of novel extended 3´ UTRs have been recently identified to be preferentially expressed in the nervous system of fly, mouse and human. Such a pervasive and cell-specific event is likely to have wide-ranging physiologically relevant consequences for nervous system development, maintenance and disease. However, to date, few functional roles for extended 3´ UTRs have been identified. The long-term objectives are to uncover functions for these extended 3´ UTR isoforms in the nervous system, and elucidate the mechanisms of their biogenesis and biological activity. The focus is on a set of genes that play established roles in axon guidance. More than ten genes with roles in axon guidance express short and extended 3´ UTR isoforms, suggesting that APA is an important regulator for this key neurodevelopmental event. Some of these genes have direct relevance to human disease. For instance, mutations in calmodulin genes are implicated in multiple cardiac defects in humans. To investigate extended 3´ UTR function, CRISPR genome editing is employed to specifically delete these isoforms in Drosophila. This approach has been established, and preliminary work has uncovered that impairment of an extended 3´ UTR isoform, while leaving the short 3´ UTR isoforms intact, can impair nervous system development. In Aim 1, this approach is expanded to cam, the Drosophila calmodulin gene. In Aim 2, the role that chromatin modifications have on the biogenesis of extended 3´ UTRs is investigated. This builds upon ongoing work on the mechanism through which the ELAV regulates 3´ UTR extension. Overall, this work will establish APA as a crucial mechanism governing multiple genes that control axon guidance.