SIGNAL TRANSDUCTION IN THE NEURONAL GROWTH CONE

神经元生长锥在脑血管畸形形成中的意义 神经系统发育过程中的特定联系 已经得到了很好的证实。这份提案描述了实验 旨在调查增长的主要组成部分之一 生长相关蛋白GAP-43的锥体膜是受调控的 在增长锥体中，最终目标是了解 生长锥能够对细胞外信号做出反应， 将它们转化为细胞内事件。GAP-43蛋白是 以两种方式进行监管；其数量受到监管，从而使其 在发育过程中生长轴突的神经元中诱导 再生，但有趣的是，它不能在 受损的神经元轴突不能再生，这意味着 它可能执行与轴突密切相关的功能 成长。其次，它的磷酸化受其他激酶的调节。 并通过自身磷酸化。这些实验使用两个主要的 神经细胞组织培养及分离生长锥体的制备 提出以下问题。首先，GAP-43是磷酸化的 通过不止一个的激酶，以及这种磷酸化是否仅限于 神经元的特定区域？第二，什么是细胞外 刺激这些激酶并使其磷酸化的信号 GAP-43调控其亚细胞分布？最后，GAP-43是 能够自动磷酸化；这一能力是否调节其 亚细胞分布或与其他蛋白质的联系？或 GAP-43是否能够磷酸化其他生长锥蛋白，因此 规范他们的行为。GAP-43与 膜，即使它不疏水。这些实验 GAP-43与膜的结合性质以及 由三种膜蛋白组成的一小群的性质 是密切相关的。最后，GAP-43是膜的一种成分 与肌动蛋白微丝交配。这件事的性质是 将对相互作用及其调节进行研究。回答 这些问题将增加我们对GAP作用的理解-- 43在生长锥体中，但也因为实验将 开发一个模型系统，将使我们能够进行更一般的调查 关于信号转导在生长锥中的作用的问题， 最终目标是利用这些知识来设计战略 它绕过了一些神经元(如哺乳动物)的故障 Cns)以成功再生。

The significance of the neuronal growth cone in the formation of specific, connections during the development of the nervous system has been well established. This proposal describes experiments designed to investigate how one of the major components of growth cone membranes, the growth-associated 'protein GAP-43, is regulated in the growth cone, with the eventual goal of understanding how the growth cone is able to respond to extracellular signals and transduce them into intracellular events. The protein GAP-43 is regulated in two ways; its amount is regulated so that it is induced in neurons that are growing axons during development or regeneration, but interestingly it cannot be re-induced in the injured axons of neurons which are unable to regenerate, implying that it may perform a function intimately connected with axon growth. Second, its phosphorylation is regulated by other kinases and by autophosphorylation. These experiments use both primary neuronal tissue culture and a preparation of isolated growth cones to ask the following questions. Firstly, is GAP-43 phosphorylated by more than one kinase, and is that phosphorylation restricted to particular areas of the neuron? Second what are the extracellular signals that stimulate these kinases and does phosphorylation of GAP-43 regulate its subcellular distribution? Finally, GAP-43 is able to autophosphorylate; does this ability regulate its subcellular distribution or association with other proteins? or is GAP-43 able to phosphorylate other growth cone proteins, and so regulate their behavior. GAP-43 is associated with membranes even though it is not hydrophobic. These experiments will the nature of GAP-43 association with membranes and also the nature of a small group of three membrane proteins with which it is closely associated. Finally GAP-43 is a component of membrane that copurifies with actin microfilaments. The nature of this interaction and its regulation will be investigated. Answers to these questions will increase our understanding of the role of GAP- 43 in the growth cone, but also, because the experiments will develop a model system, will enable us to investigate more general questions about the role of signal transduction in the growth cone, with the eventual goal of using this knowledge to design strategies which circumvent the failure of some neurons (such as mammalian CNS) to regenerate successfully.