Role of Semaphorins in axonal guidance

信号蛋白在轴突引导中的作用

• 批准号: 6471379
• 负责人: JOHN Y KUWADA
• 金额: $ 35.38万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6471379
• 关键词: chemoattractants; developmental neurobiology; embryo /fetus; gene expression; genetically modified animals; growth cones; lasers; macromolecule; neurogenesis; neuronal guidance; protein structure function; recombinant proteins; zebrafish

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.

描述（由申请人提供）：信号蛋白是一个大家族 排斥生长锥的分子，但在某些情况下也会吸引它们。这 对信号蛋白及其神经毡蛋白/丛蛋白受体的分析表明 我们对生长锥如何被引导到其生长的理解取得了重要进展 目标。然而，我们对信号蛋白功能的认识仍然不够深入。 不完整。首先，对脊椎动物信号蛋白进行了功能分析。 大部分是分泌的 3 类信号蛋白。我们对函数的理解 大跨膜中，4 类信号蛋白仅限于 Sema4D/CD100， 在免疫系统中起着至关重要的作用，但没有神经系统功能 以任何 4 类信号素而闻名。该应用程序将检查 Sema4E（一个 我们的实验室最近克隆了新型 4 类信号蛋白，可引导生长锥 斑马鱼胚胎。其次，大多数影响神经元的脊椎动物信号蛋白 尽管在某些情况下，但对轴突表现出排斥作用 信号蛋白可以在体外吸引生长锥。尽管如此，没有 体内脊椎动物信号蛋白对轴突有吸引力作用的例子。 此应用程序将检查 Sema3D 是否在任何功能中未知 生物体，在斑马鱼体内通过轴突吸引和/或诱导分支 胚胎。 胚胎的可接近性、可操作性和透明度导致 高分辨率、细胞分析特定生长锥如何找到它们的 斑马鱼的目标。此外，我们的实验室已经产生了转基因 斑马鱼中可以诱导多种信号蛋白，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”信号蛋白 应用显性消极策略。初步证据表明 Sema4E 和 Sema3Al 可能会限制鳃运动轴突的正常通路，而 Sema3D 可能会吸引或诱导咽弓目标内的分支 这些轴突。该应用程序将使用这些转基因品系并产生新的 为了测定 Sema4E 的功能获得和丧失表型， Sema3Al 和 Sema3D 阐明它们在指导鳃运动方面的作用 生长锥到达它们所支配的咽弓并在其内。