Molecular Events Within the Neuronal Growth Cone

神经元生长锥内的分子事件

• 批准号: 0544710
• 负责人: Daniel Goldberg
• 金额: --
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0544710&HistoricalAwards=false
• 关键词: Molecular; Events; Within; Neuronal; Growth

During development of the nervous system, as well as regeneration after injury, the axons of many neurons must grow long distances through complicated terrain to make synaptic connection with appropriate targets. Growth of an axon is controlled by activities of its motile ending, the growth cone. Thus, elucidating the molecular machinery within the growth cone that causes axonal elongation and the molecular mechanisms whereby external cues affect that machinery are very important goals of the study of development and regeneration of the nervous system. Work in this project is designed to help understand how microtubules, major components of the cytoskeleton of the growth cone, are regulated to affect the rate and direction of axonal growth. There is little molecular understanding of this regulation of microtubules, though its importance is becoming evident. Experiments will focus on changes in microtubule behavior in the growth cone that underlie rapid, streamlined growth of differentiated axons. Recent work points to the molecular motor, cytoplasmic dynein, as playing an important role in regulating aspects of this behavior. In particular, experiments in this project will test the hypothesis that dynein functions at the interface of the ends of microtubules and the subplasmalemmal actin cortex to capture microtubules and facilitate their bundling and the coordinated streamlining of the axon. Experiments will determine how the elongation of axons is affected by inactivation of dynein. Which specific aspects of microtubule behavior in the growth cone are sensitive to inactivation of dynein will then be determined so as to understand how the regulation of axonal elongation is achieved. The potential involvement of dynein in the turning of growth cones towards environmental cues will also be examined. High resolution fluorescence microscopy will be a major experimental technique for this project. This will include observations of microtubules within living growth cones after transfection of XFP-protein constructs. Function-blocking antibodies introduced by microinjection or RNAi will be used to inactivate specific proteins within growth cones. This project addresses basic issues in neuronal development involving the growth and guidance of the axon, the long projecting process of the neuron. The work is also relevant to the design of strategies to foster nerve regeneration after spinal cord injury and stroke, when the stimulation of long distance axonal growth is important. These are potential benefits to society at large. In addition, this project will integrate research and education in two ways. Undergraduate science majors will participate in the research during the summer and, probably, the academic year as well. Also, secondary school science teachers may participate in the research during the summer in a program designed to enrich their teaching. The productive incorporation of the undergraduates and teachers in the research is facilitated by the pervasive use of video microscopy, a technique both engaging to do and relatively easy to learn. The work could explore the possibility of incorporating video microscopy as a tool into the secondary school biology curriculum. Lastly, it is expected that one of the undergraduates employed during the summer will be a minority student, as part of a program to enhance the participation of underrepresented groups in research science.

在神经系统的发育以及损伤后的再生过程中，许多神经元的轴突必须通过复杂的地形长距离生长，以便与适当的目标建立突触连接。 轴突的生长由其运动末端（生长锥）的活动控制。 因此，阐明生长​​锥内导致轴突伸长的分子机制以及外部线索影响该机制的分子机制是神经系统发育和再生研究的非常重要的目标。 该项目的工作旨在帮助了解微管（生长锥细胞骨架的主要组成部分）如何被调节以影响轴突生长的速率和方向。 尽管其重要性正变得越来越明显，但对微管这种调节的分子了解还很少。 实验将重点关注生长锥中微管行为的变化，这是分化轴突快速、流线型生长的基础。 最近的工作指出分子马达、细胞质动力蛋白在调节这种行为方面发挥着重要作用。 特别是，该项目的实验将测试以下假设：动力蛋白在微管末端和质膜下肌动蛋白皮层的界面上发挥作用，以捕获微管并促进其捆绑和轴突的协调流线型化。 实验将确定动力蛋白失活如何影响轴突的伸长。 然后将确定生长锥中微管行为的哪些具体方面对动力蛋白失活敏感，以便了解如何实现轴突伸长的调节。 动力蛋白在生长锥转向环境线索中的潜在参与也将被研究。 高分辨率荧光显微镜将是该项目的主要实验技术。 这将包括 XFP 蛋白构建体转染后活生长锥内微管的观察。 通过显微注射或 RNAi 引入的功能阻断抗体将用于灭活生长锥内的特定蛋白质。 该项目解决了神经元发育中的基本问题，涉及轴突的生长和引导，即神经元的长期投射过程。 这项工作还与脊髓损伤和中风后促进神经再生的策略设计相关，此时长距离轴突生长的刺激很重要。 这些都是对整个社会的潜在好处。 此外，该项目还将通过两种方式整合研究和教育。 理科专业的本科生将在夏季甚至整个学年参与研究。 此外，中学科学教师可以在暑假期间参与一项旨在丰富其教学的项目的研究。 视频显微镜的普遍使用促进了本科生和教师富有成效地参与研究，这种技术既有趣又相对容易学习。 这项工作可以探索将视频显微镜作为一种工具纳入中学生物课程的可能性。 最后，预计夏季受聘的一名本科生将是少数族裔学生，作为加强代表性不足群体参与研究科学研究计划的一部分。