Sema3D Role in Retinal Axon Guidance and Cell Migration

描述（由申请人提供）：信号蛋白参与轴突寻路的调节，有时作为抑制性指导分子，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。信号蛋白也被认为在发育、转移和侵袭性生长过程中控制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迁移错误是颅面结构中许多出生缺陷的基础。对信号素控制神经嵴迁移的机制的研究将有助于了解颅面发育，也许也有助于了解癌症进展中浸润性生长的一般机制。本应用程序的目的是了解一个信号蛋白Sema3D在斑马鱼发育过程中指导视网膜顶轴突寻路和神经嵴细胞迁移的体内功能。Sema3D在引导视网膜轴突穿过中线和在顶盖上进行地形测绘中的作用将被研究。此外，Sema3D在控制细胞运动中的作用将被研究，以验证Sema3D诱导神经嵴迁移的开始，和/或维持迁移的神经嵴流分离的假设。我们的策略是研究Sema3D异位表达和Sema3D功能缺失对这些系统发育的影响，以及对活体生长锥和体内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。在转基因斑马鱼中，Sema3D可以在任何所需发育阶段的选定细胞中错误表达。此外，Sema3D功能可以被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，所提出的实验可能会为信号素如何调节视网膜轴突发育和神经嵴细胞在复杂的体内环境中的迁移提供新的见解。

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.