Sema3D Role in Retinal Axon Guidance and Cell Migration

描述(申请人提供)：信号素涉及轴突寻路的调节，有时作为抑制性引导分子，有时吸引人。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以及损伤后轴突再生的条件都是至关重要的。信号素也被认为在发育、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。颅神经脊细胞从神经管中迁移，形成颅面结构和周围神经系统。发育过程中颅神经脊移移错误是许多颅面结构先天缺陷的基础。研究信号素控制神经脊迁移的机制将有助于深入了解颅面发育，也可能是参与癌症进展的侵袭性生长的一般机制。本应用的目的是了解信号素Sema3d在体内的功能，指导斑马鱼发育中的视网膜轴突轴突路径和神经脊细胞迁移。将研究Sema3d在引导视网膜轴突穿过中线以及在顶盖上的地形图中的作用。此外，将研究Sema3d在控制细胞运动中的作用，以检验Sema3d诱导神经峰迁移的开始和/或维持迁移的神经峰流分离的假设。我们的策略是研究Sema3d异位表达和Sema3d功能丧失对这些系统的发育以及体内活的生长锥和迁移的神经脊细胞的动态行为的影响。斑马鱼胚胎非常适合我们开发的各种方法的组合。利用转基因斑马鱼，Sema3d可以在任何所需的发育阶段在选定的细胞中错误表达。此外，Sema3d功能可以用反义或显性否定方法破坏。时间推移显微镜可以直接显示胚胎中活的生长锥体或迁移细胞的反应。因此，拟议的实验可能会为信号素如何在复杂的体内环境中调节视网膜轴突发育和神经脊细胞迁移提供新的见解。

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.