Mechanisms of Slit-Roundabout Mediated Axon Repulsion

发育中的神经系统中的轴突如何成功地导航到其 正确的靶点是神经生物学中的一个基本问题。轴突由两者引导 吸引和排斥的提示，这是进化保守蛋白质的成员 家人。我们建议研究在排斥中起作用的信号机制。 轴突引导。果蝇胚胎中枢神经系统的中线 为解决这些问题提供了一个理想的系统。就像它的结构模拟一样， 脊椎动物的底板，苍蝇中线是许多类别的中间目标 导航轴突，这必须决定是否交叉。在果蝇中枢神经系统中， 保守的引导线索狭缝及其神经元感受器环形交叉路口(ROBO)， 在形成中线轴突连接的模式中扮演多种角色，主要起到 轴突驱避剂。这项提议的主要目的是：1)检验假设 蛋白质降解处理直接导致ROBO排斥和信号终止，2) 为了调查识别出的Robo信号组件Seven less的儿子Abelson 和CrossGAP一起协调ROBO和3)下游的信令 剖析这三种不同的排斥功能背后的机制 果蝇Robo家族成员。我们已经建立了遗传和直接生化 一种特定的金属蛋白酶与ROBO排斥力的调节之间的联系 必要的遗传、生化和细胞生物学检测以研究其发病机制 蛋白分解过程通过其影响排斥力。类似的方法也很好 将使我们能够继续研究信号是如何 ROBO下游的分子协调调节轴突排斥力。一个 以前成功的嵌合受体方法中，Robo1的不同部分， ROBO2和Robo3受体相互交换，然后检测 转基因果蝇的功能将被用来理解不同的Robo受体如何导致 到不同的令人厌恶的事件。总之，这些研究有望丰富我们的理解 Sit-Robo信号在正常发育过程中的作用，并可能提供新的治疗方法 针对各种人类健康问题的目标，从儿童的发育障碍 神经系统到脊髓损伤和中风。

How axons in the developing nervous system successfully navigate to their correct targets is a fundamental problem in neurobiology. Axons are guided by both attractive and repulsive cues, which are members of evolutionary conserved protein families. We propose to study the signaling mechanisms that function during repulsive axon guidance. The midline of the Drosophila embryonic central nervous system (CNS) provides an ideal system to address these questions. Like its structural analog, the vertebrate floor plate, the fly midline is an intermediate target for many classes of navigating axons, which must decide whether or not to cross. In the Drosophila CNS, the conserved guidance cue Slit and its neuronal receptors the Roundabouts (Robo), play multiple roles in patterning axonal connections at the midline, acting primarily as axonal repellants. The primary aims of this proposal are to 1) test the hypothesis that proteolytic processing directly contributes to Robo repulsion and to signal termination, 2) to investigate how the identified Robo signaling components Abelson, Son of Sevenless and CrossGAP function together to coordinate signaling downstream of Robo and 3) to dissect the mechanisms underlying the distinct repulsive functions of the three Drosophila Robo family members. We have established genetic and direct biochemical links between a specific metalloprotease and regulation of Robo repulsion and have the necessary genetic, biochemical and cell biological assays to investigate the mechanism by which proteolytic processing influences repulsion. Similar kinds of approaches well established in our laboratory will allow for our continued investigation of how signaling molecules that function downstream of Robo coordinately regulate axon repulsion. A previously successful chimeric receptor approach where different portions of the Robo1, Robo2 and Robo3 receptors are exchanged with each other and then assayed for function in transgenic flies will be used to understand how different Robo receptors lead to distinct repulsive events. Together these studies promise to enrich our understanding of Slit-Robo signaling during normal development and may provide new therapeutic targets for diverse human health problems, ranging from developmental disorders of the nervous system to spinal cord injury and stroke.