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它们的 正确的靶点是神经生物学中的一个基本问题。轴突受两者的引导 吸引和排斥的线索，这是进化保守蛋白质的成员 家庭我们建议研究在排斥过程中起作用的信号机制， 轴突导向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。与其结构类似， 脊椎动物底板，蝇中线是许多类别的中间目标， 导航轴突，它必须决定是否交叉。在果蝇中枢神经系统中， 保守的引导因子Slit及其神经元受体Roundarium（Robo）， 在中线的轴突连接模式中发挥多种作用，主要作为 轴突排斥剂本提案的主要目的是：1）检验以下假设： 蛋白水解加工直接有助于Robo排斥和信号终止，2） 为了研究确定的机器人信号组件Abelson，Son of Sevenless 和CrossGAP一起起作用以协调Robo下游的信令，以及3） 剖析这三个不同的排斥功能背后的机制 Drosophila Robo家族成员我们已经建立了遗传和直接生化 之间的联系，一个特定的金属蛋白酶和调节机器人排斥，并有 必要的遗传、生物化学和细胞生物学分析，以研究其机制 蛋白水解过程通过其影响排斥。类似的方法 建立在我们的实验室将允许我们继续调查如何信号 在Robo下游起作用的分子协调调节轴突排斥。一 先前成功的嵌合受体方法，其中Robo1的不同部分， 将Robo2和Robo3受体彼此交换，然后测定 转基因果蝇的功能将用于了解不同的Robo受体如何导致 不同的排斥事件。这些研究一起保证丰富我们的理解 Slit-Robo信号在正常发育过程中的作用，并可能提供新的治疗 目标的各种人类健康问题，从发展障碍的 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.