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.

在神经系统的发育和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，才能与合适的靶点建立突触连接。轴突的生长受其活动末端——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重要目标。该项目的工作旨在帮助理解微管（生长锥细胞骨架的主要组成部分）是如何被调节以影响轴突生长的速度和方向的。虽然微管的重要性越来越明显，但对微管调控的分子理解却很少。实验将集中在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，在调节这种行为的各个方面起着重要作用。特别是，本项目的实验将验证动力蛋白在微管末端和质下肌动蛋白皮层的界面上起作用的假设，以捕获微管并促进它们的捆绑和轴突的协调流线型。实验将确定动力蛋白失活如何影响轴突的伸长。生长锥中微管行为的哪些特定方面对动力蛋白失活敏感，然后将确定，以便了解轴突伸长的调节是如何实现的。动力蛋白在生长锥转向环境线索的潜在参与也将被检查。高分辨率荧光显微镜将是本项目的主要实验技术。这将包括在转染xfp蛋白构建物后观察活生长锥内的微管。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。该项目涉及神经元发育的基本问题，包括轴突的生长和引导，神经元的长投射过程。这项工作也与脊髓损伤和中风后促进神经再生的策略设计有关，当长距离轴突生长的刺激是重要的。这些都是对整个社会的潜在好处。此外，该项目将以两种方式整合研究和教育。本科理科专业的学生将在夏季参与这项研究，可能在学年也会参与。此外，中学科学教师也可以在夏季参加一个旨在丰富其教学的项目的研究。视频显微镜的广泛使用促进了本科生和教师在研究中的有效结合，这是一种既吸引人又相对容易学习的技术。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，预计在夏季雇用的本科生中有一名是少数民族学生，作为提高代表性不足的群体参与研究科学的计划的一部分。