Role of Semaphorins in axonal guidance

描述(申请人提供)：信号语是一个很大的家族 排斥生长锥的分子，但在某些情况下也会吸引它们。这个 对信号素及其神经粘连蛋白/丛蛋白受体进行了分析 我们对生长锥体如何被引导到它们的 目标。然而，我们对信号素的功能的理解仍然是 不完整。首先，对脊椎动物信号素的功能进行了分析 主要是分泌的3类信号素。我们对功能的理解 在大跨膜蛋白中，4类信号素仅限于Sema4D/CD100 在免疫系统中起着至关重要的作用，但神经系统功能却不是 以任何4类信号量而闻名。这个应用程序将检查Sema4E是如何 本实验室新近克隆的一种新的4类信号素，它引导生长锥体的生长 斑马鱼胚胎。其次，大多数脊椎动物的信号素会影响神经元 表现出对轴突的排斥作用，尽管在某些情况下 在体外，信号素可以吸引生长锥。尽管如此，没有 脊椎动物体内信号素对轴突的吸引作用的例子。 此应用程序将检查其功能未知的Sema3d是否在任何 生物体，通过体内轴突吸引和/或诱导斑马鱼的分支 胚胎。 胚胎的可及性、可操控性和透明度导致了 对特定生长锥体如何找到它们的高分辨率细胞分析 斑马鱼的目标。此外，我们的实验室已经产生了转基因 斑马鱼可以诱导几种信号素，表明转基因 可以通过将激光微束聚焦到细胞上在单个细胞中激活， 通过注射吗啡反义寡核苷酸和 运用显性消极策略。初步证据表明，Sema4E 而Sema3Al可能会将分支运动性轴突限制在其正常路径上，而 Sema3d可吸引或诱导咽弓靶点内的分支 这些轴突。这个应用程序将使用这些转基因株系并生成新的 为了分析Sema4E的功能增强型和失调型， Sema3Al和Sema3d阐明它们在指导分支运动方面的作用 生长锥体位于它们支配的咽弓和咽弓内。

DESCRIPTION (provided by applicant): Semaphorins are a large family of molecules that repulse growth cones, but in some cases also attract them. The analyses of semaphorins and their neuropilin/plexin receptors have made important advances in our understanding of how growth cones are guided to their targets. However, our understanding of the function of semaphorins is still incomplete. First, the functional analysis of vertebrate semaphorins has been mostly of the secreted, Class 3 semaphorins. Our understanding of the function of the large transmembrane, Class 4 semaphorins is limited to Sema4D/CD100which plays a vital role in the immune system, but no nervous system function is known for any Class 4 semaphorin. This application will examine how Sema4E, a novel Class 4 semaphorin recently cloned by our lab, guides growth cones in the zebrafish embryo. Second, most vertebrate semaphorins that affect neurons exhibit a repulsive effect on axons, although in certain circumstances semaphorins can attract growth cones in vitro. Nevertheless, there are no examples of attractive actions on axons by a vertebrate semaphorin in vivo. This application will examine whether Sema3D, whose function is unknown in any organism, attracts and/or induces branching by axons in vivo in zebrafish embryos. The accessibility, manipulability, and transparency of the embryo have led to high resolution, cellular analyses of how specific growth cones find their targets in zebrafish. Furthermore, our laboratory has generated transgenic zebrafish in which several semaphorins can be induced, shown that transgenes can be activated in individual cells by focusing a laser microbeam onto cells, "knocked down" semaphorins by injection of morpholino antisense oligos and applied dominant negative strategies. Preliminary evidence suggests that Sema4E and Sema3Al may restrict branchiomotor axons to their normal pathway, while Sema3D may attract or induce branching within the pharyngeal arch targets of these axons. This application will use these transgenic lines and generate new ones in order to assay both gain- and loss-of-function phenotypes for Sema4E, Sema3Al, and Sema3D to clarify their roles for guidance of the branchiomotor growth cones to and within the pharyngeal arches that they innervate.