Approaches to studying axon fasciculation

描述(申请人提供)：了解轴突如何找到它们的突触目标是神经发育中的一个基本问题。虽然在阐明轴突引导的机制方面已经取得了很大进展，但关于轴突如何在神经束的特定区域内形成束状组织的了解还很少。我们建议在线虫中研究这个问题，重点是HSN轴突。在整个神经系统建立后，HSN轴突沿着腹神经索延伸。HSN生长锥沿PVQ和PVP轴突呈束状分布，该项目的短期目标是确定定义HSN在神经束中沿着其特定路径生长的线索。虽然对哺乳动物神经中的轴突如何成束知之甚少，但最近的发现表明，神经中嗅觉轴突的分类在它们瞄准嗅球的过程中很重要。HSN可能为哺乳动物这种神经的组织方式提供了一个模型。该提案有三个具体目标。在第一个目标中，不同轴突之间的界面将使用GRASH进行标记。在第二个目标中，将开发RNAi方法来识别参与HSN轴突分束的基因。这些方法应该绕过基本基因的RNAi造成的致命影响，以及其他轴突早期缺陷造成的间接影响。在第三个目标中，将测试这些方法以阐明神经递质乙酰胆碱在轴突颤动中的作用。 与公共健康相关：了解这些轴突如何找到它们的目标是神经发育中的一个基本问题。虽然在阐明轴突引导机制方面取得了很大进展，但关于轴突是如何沿着神经束的特定区域生长的还知之甚少。我们建议在秀丽线虫中研究这个问题，线虫是一种模式生物，它在确定具有轴突引导功能的保守分子方面发挥了重要作用。

DESCRIPTION (provided by applicant): Understanding how axons find their synaptic targets is a fundamental problem in neurodevelopment. While great progress has been made in elucidating the mechanisms of axon guidance, less is known about how axons fasciculate within specific regions of a nerve bundle. We propose to study this problem in C. elegans with a focus on the HSN axon. The HSN axon extends along the ventral nerve cord after the entire nervous system has been established. The HSN growth cone fasciculates along the PVQ and PVP axons, and the short-term goal of this project is to identify the cues that define the HSN's ability to grow along its specific path in the nerve bundle. While little is known about how axons fasciculate within mammalian nerves, recent findings suggest that sorting of olfactory axons within the nerve are important in their targeting at the olfactory bulb. The HSN may provide a model for how such nerves are organized in mammals. The proposal has three specific aims. In the first aim, the interface between the different axons will be labeled using GRASP. In the second aim, RNAi approaches to identify genes involved in HSN axon fasciculation will be developed. These approaches should bypass the lethal effects caused by RNAi of essential genes and indirect effects caused by earlier defects in the fasciculation of other axons. In the third aim, the approaches will be tested to elucidate the role of the neurotransmitter acetylcholine in axon fasciculation.. PUBLIC HEALTH RELEVANCE: Understanding how these axons find their targets is a fundamental problem in neurodevelopment. While great progress has been made in elucidating the mechanisms of axon guidance, less is known about how axons grow along specific regions of a nerve bundle. We propose to study this problem in C. elegans, a model organism that has been instrumental in defined conserved molecules that function axon guidance.