Regulation of Axon Guidance by Second Messengers

描述(逐字摘自申请者摘要)：的长期目标 这项研究是为了更好地了解信号转导级联和 引导轴突延伸所必需的细胞骨架重排 活着。将生长锥体引导到其目标需要具体和 多个细胞外配体与细胞表面受体的相互作用 生长锥体的表面。而可扩散的大家族，细胞表面和 细胞外基质(ECM)结合的配体及其受体已被 经鉴定，对细胞内信号系统的了解相对较少。 以及受体-配体相互作用下游的细胞骨架重排。 在发育中的胚胎中尤其如此，在那里生长锥体必须 通过与以下各项的动态组合交互而生成的积分信号 神经系统中的分子梯度、指南针和边界。 细胞内钙和cAMP是两个关键的第二信使系统，它们具有 已被证明可以调节轴突的生长和引导。肌动蛋白细丝和 微管是细胞骨架的两个关键元件，它们是 生长锥运动和细胞外线索的检测。这项研究提出 研究钙瞬变、cAMP信号和细胞骨架的作用 非洲爪哇脊椎发育过程中特定选择点的重排 脐带和/或在体外创建的人工选择点处使用特定的 荧光探针、笼状化合物、药理剂和分子 微扰。具体地说，我们建议：1)确定钙的作用 运动神经元(MN)和连合在发散选择中的暂时性 脊髓腹侧束选择点处的中间神经元(CI)生长锥 脊髓。2)研究cAMP依赖的蛋白激酶信号转导功能 在CI的引导下穿过地板。3)评估地方和地方的作用 在衬底边界处转动的生长锥体中的全局钙瞬变 体外培养。4)描述自发性和外加性钙的影响 生长锥体细胞骨架动力学的瞬变。这些研究将提供新的 关于第二信使变化在引导 在活体内的选择点处生长锥体。这是重要和必要的一步。 在我们对生长锥体定位的机制的理解中 在发育中的胚胎的复杂环境中的靶标。此外，这一点 研究将确定瞬变的全球和局部高程如何 信使调节细胞骨架的动态组装和拆卸 控制生长锥体运动的组件。

DESCRIPTION (Verbatim from the Applicant's Abstract): The long range goal of this research is to better understand the signal transduction cascades and cytoskeletal rearrangements that are necessary for guided axon extension in vivo. Guidance of growth cones to their targets requires specific and interactions between multiple extracellular ligands with receptors on the surface of growth cones. While large families of diffusible, cell surface and extracellular matrix (ECM) bound ligands and their receptors have been identified, relatively little is known of the intracellular signaling systems and cytoskeletal rearrangements downstream of receptor-ligand interactions. This is especially true within the developing embryo, where growth cones must integrate signals generated by interactions with dynamic combinations of molecular gradients, guideposts and boundaries in the nervous system. Intracellular calcium and cAMP are two key second messenger systems that have been shown to regulate axon growth and guidance. Actin filaments and microtubules are two key cytoskeletal elements that are required for proper growth cone motility and detection of extracellular cues. This study proposes to investigate the role of calcium transients, cAMP signaling and cytoskeletal rearrangements at specific choice points within the developing Xenopus spinal cord and/or at artificial choice points created in vitro using specific fluorescent probes, caged-compounds, pharmacological agents and molecular perturbations. Specifically, we propose to: 1)Determine the role of calcium transients in the divergent choice made by motoneuron (MN) and commissural interneuron (CI) growth cones at the ventral fascicle choice point in the spinal cord. 2) Examine the function of cAMP-dependent protein kinase signaling in the guidance of CI's through the floorplate. 3)Assess the role of local and global calcium transients in growth cone turning at a substrate boundary in vitro. 4)Characterize the effects of spontaneous and imposed calcium transients on growth cone cytoskeletal dynamics. These studies will provide new information about the role of second messenger changes in the guidance of growth cones at choice points in vivo. This is an important and necessary step in our understanding of the mechanisms by which growth cones locate their targets in the complex environment of a developing embryo. In addition, this study will identify how transient global and local elevations of second messengers regulate the dynamic assembly and disassembly of cytoskeletal components that control growth cone motility.