Role of Semaphorins in axonal guidance

描述（由申请人提供）：信号蛋白是一个大家族 这些分子排斥生长锥，但在某些情况下也吸引它们。的 对脑信号蛋白和它们的神经纤毛蛋白/丛蛋白受体的分析已经使得 重要的进展，我们的理解如何生长锥引导他们的 目标的然而，我们对信号蛋白功能的理解仍然是 不完整首先，脊椎动物脑信号蛋白的功能分析已经被 大部分是分泌的第三类信号蛋白我们对功能的理解 在大跨膜蛋白中，4类信号蛋白仅限于Sema 4D/CD 100， 在免疫系统中起着至关重要的作用，但没有神经系统的功能， 以4类信号蛋白而闻名这个应用程序将研究Sema 4 E，一个 我们实验室最近克隆了一种新的4类信号蛋白， 斑马鱼胚胎其次，大多数影响神经元的脊椎动物信号蛋白 对轴突有排斥作用，尽管在某些情况下 semaphorins可以吸引生长锥在体外。然而，没有 脊椎动物脑信号蛋白在体内对轴突的吸引作用的例子。 这个应用程序将检查Sema 3D，其功能是未知的， 生物体，吸引和/或诱导分支的轴突在体内斑马鱼 胚胎 胚胎的可接近性、可操作性和透明度导致了 高分辨率，细胞分析如何特定的生长锥找到他们的 斑马鱼中的目标。此外，我们的实验室已经产生了转基因 斑马鱼，其中几个信号蛋白可以诱导，表明转基因， 可以通过将激光微束聚焦到细胞上来激活单个细胞， 通过注射吗啉代反义寡核苷酸“敲低”的信号蛋白， 采用显性消极策略。初步证据表明Sema 4 E 和Sema 3Al可能限制鳃纤维轴突的正常通路，而 Sema 3D可以吸引或诱导咽弓内的分支， 这些轴突本申请将使用这些转基因品系并产生新的 一种是为了测定Sema 4 E的功能获得和丧失表型， Sema 3Al和Sema 3D，以澄清其在指导分支机构方面的作用 生长锥和咽弓内，他们支配。

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.