Sema3D Role in Retinal Axon Guidance and Cell Migration

描述（由申请人提供）：脑信号蛋白与轴突寻路的调节有关，有时作为抑制性引导分子，有时具有吸引力。了解促进和抑制轴突生长的复杂过程对于理解神经发育疾病和损伤后轴突再生的条件至关重要。脑信号蛋白也被认为在控制发育、转移和侵袭性生长期间的细胞迁移的相关过程中发挥作用。颅神经嵴细胞从神经管迁移形成颅面结构和周围神经系统。颅神经嵴在发育过程中的移位错误是许多颅面结构出生缺陷的基础。semaphorins控制神经嵴迁移的机制的调查将提供深入了解颅面发育，也可能是一般机制的侵入性生长参与癌症progression. This应用程序的目的是了解在体内功能的一个semaphorin，Sema 3D，在指导retinotectal轴突寻路和神经嵴细胞迁移在发展中的斑马鱼。Sema 3D在引导视网膜轴突穿过中线和地形图映射到顶盖上的作用将被研究。此外，Sema 3D在控制细胞运动性的作用将进行调查，以测试的假设，Sema 3D诱导神经嵴迁移的发病，和/或保持分离的迁移神经嵴流。我们的策略是研究Sema 3D异位表达和Sema 3D功能丧失对这些系统发展的影响，以及对活体生长锥和迁移神经嵴细胞的动态行为的影响。斑马鱼胚胎非常适合我们开发的方法组合。对于转基因斑马鱼，Sema 3D可以在任何期望的发育阶段在选择的细胞中错误表达。此外，Sema 3D功能可以用反义或显性阴性方法破坏。延时显微镜可以直接观察胚胎中活的生长锥或迁移细胞的反应。因此，拟议的实验可能会提供新的见解semaphorins如何调节视网膜轴突的发展和神经嵴细胞迁移在复杂的体内环境。

DESCRIPTION (provided by applicant): Semaphorins have been implicated in the regulation of axon pathfinding, sometimes acting as inhibitory guidance molecules, and other times attractive. An understanding of the complex processes involved in promoting and inhibiting axon growth will be crucial for understanding both diseases of neural development, and the conditions under which axon regeneration after injury can occur. Semaphorins also are thought to play a role in controlling the related processes of cell migration during development, metastasis and invasive growth. Cranial neural crest cells migrate from the neural tube to form craniofacial structures and peripheral nervous system. Errors in migration of cranial neural crest during development underlies many birth defects in craniofacial structure. An investigation of the mechanisms by which semaphorins control neural crest migration will provide insight into craniofacial development, and perhaps also general mechanisms of invasive growth involved in cancer progression.The aim of this application is to understand the in vivo function of one semaphorin, Sema3D, in guiding retinotectal axon pathfinding and neural crest cell migration in the developing zebrafish. Sema3D's role in guiding retinal axons across the midline and in topographic mapping onto the tectum will be investigated. In addition, Sema3D's role in controlling cell motility will be investigated to test the hypotheses that Sema3D induces the onset of neural crest migration, and/or maintains separation of migrating neural crest streams. Our strategy is to examine effects of both Sema3D ectopic expression and Sema3D loss-of-function on the development of these systems, and on dynamic behaviors of living growth cones and migrating neural crest cells in vivo. The zebrafish embryo is ideally suited to the combination of approaches we have developed. With transgenic zebrafish, Sema3D can be misexpressed in select cells at any desired developmental stage. In addition, Sema3D function can be disrupted with antisense or dominant negative methods. Time-lapse microscopy allows direct visualization of the responses of living growth cones or migrating cells in the embryo. Thus the proposed experiments will likely provide novel insights into how semaphorins regulate retinal axon development and neural crest cell migration within the complex in vivo environment.