C. elegans model for mammalian lesion-conditioned axon regeneration

描述(申请人提供)：中枢神经系统(CNS)损伤在美国每年折磨着数百万人，缺乏有效的治疗方法。这种损伤后恢复丧失的功能的一个基本障碍是中枢神经系统再生能力较弱。神经治疗学中最令人兴奋的发现之一是，如果对哺乳动物的外周感觉轴突进行条件性损伤，哺乳动物神经元可以强烈地再生进入或超出损伤部位的中枢轴突。确定参与损伤条件作用的通路的关键组成部分将是成功治疗中枢神经系统损伤的关键一步。哺乳动物系统对基因操作的相对困难阻碍了理解病变条件作用的进展，但在一个更简单、基因易处理的生物体中模拟病变条件作用可能会带来快速突破。小蛔虫线虫是一种极其有用的模式生物，具有无与伦比的遗传可操作性。20世纪90年代末，线虫的研究人员注意到，异位轴突是从几个神经元中长出来的，这些神经元的电活动因突变而沉默。使用先进的激光手术技术解剖完整的成年线虫的单个神经元，我们在这些感觉神经元中观察到强烈的损伤条件化效应。最近发表的数据表明，哺乳动物病变条件反射中的电活动受到抑制，以及我们的再生实验与以前对线虫异位生长的研究之间的相似性，表明所有这些过程都高度相关，并共享遗传路径。这项拟议的研究的目标是建立线虫异位生长作为哺乳动物损伤条件作用的遗传易处理模型。目标1的实验将进一步证明和表征刺激异位生长的神经元活动的减少，以及我们在线虫中观察到的损伤条件效应。这些结果有望将活动减少与轴突再生联系起来，并进一步确定活动在异位生长中的作用。Aim 2的实验试图开发一种正向筛选，以确定介导异位轴突生长和损伤条件性再生的基因。该筛选将识别抑制线虫异位轴突生长和轴突再生的新基因，其中同源哺乳动物基因介导高等动物的损伤条件反射。通过开发一个遗传上可处理的病变条件作用模型，这些研究将为快速和变革性的研究奠定基础，这些研究具有巨大的潜力来阐明这一非凡的再生途径的关键组成部分。所获得的知识将为利用神经系统固有的再生能力治疗中枢神经系统损伤提供新的治疗途径。 与公共卫生相关：识别参与损伤条件作用的通路的关键组成部分，刺激中枢神经系统的强大再生，是成功治疗脊髓损伤的关键一步。基于我们的初步发现，这项拟议的研究旨在建立线虫秀丽线虫作为研究病变条件作用的遗传易处理的模式系统。因此，它将促进在这些非凡的途径中发现新的基因和分子成分，为利用神经系统内在再生能力的治疗铺平道路。

DESCRIPTION (provided by applicant): Injuries to the central nervous system (CNS) afflict millions of people in the United States each year and lack an effective therapy. A fundamental barrier to recovering lost function after such injuries is weak CNS regeneration. One of the most exciting discoveries in neurotherapeutics is that mammalian neurons can strongly regenerate their central axons into and beyond an injury site if a conditioning lesion is made on their peripheral sensory axons. Identifying critical components of the pathways involved in lesion conditioning would represent a key step toward successfully treating CNS injuries. The relative intractability of mammalian systems to genetic manipulation has hampered progress toward understanding lesion conditioning, but rapid breakthroughs could result from modeling lesion conditioning in a simpler, genetically-tractable organism. The small roundworm C. elegans is an extremely useful model organism with unparalleled genetic manipulability. In the late 1990s C. elegans researchers noted ectopic axons outgrowing from several neurons whose electrical activity was silenced by mutation. Using advanced laser surgery techniques to dissect individual neurons within intact adult C. elegans, we observe a strong lesion conditioning effect in these same sensory neurons. Recently-published data implicating suppression of electrical activity in mammalian lesion conditioning, as well as similarities between our regeneration experiments and previous studies on ectopic outgrowth in C. elegans, indicate that all these processes are highly related and share genetic pathways. The goal of the proposed research is to establish ectopic outgrowth in C. elegans as a genetically tractable model for mammalian lesion conditioning. Experiments for aim 1 will further demonstrate and characterize the reduction of neuronal activity that stimulates ectopic outgrowth and the lesion conditioning effect we observe in C. elegans. Results are expected to correlate reduced activity with axon regeneration and further ascertain the role of activity in ectopic outgrowth. Experiments for aim 2 seek to develop a forward screen to identify genes mediating ectopic axon outgrowth and lesion conditioned regeneration. The screen will identify novel genes that suppress both ectopic axon outgrowth and axon regeneration in C. elegans, with homologous mammalian genes mediating lesion conditioning in higher animals. By developing a genetically tractable model for lesion conditioning, these studies will lay the foundation for expedited and transformative research that has tremendous potential to illuminate critical components of this remarkable regeneration pathway. The knowledge gained will suggest new therapeutic avenues for treating CNS injuries by exploiting the nervous system's intrinsic regenerative capability. PUBLIC HEALTH RELEVANCE: Identifying critical components of the pathways involved in lesion conditioning, which stimulates strong regeneration in the central nervous system, represents a key step toward successfully treating spinal cord injuries. Motivated by our preliminary findings, the proposed research aims to establish the roundworm Caenorhabditis elegans as a genetically tractable model system for the study of lesion conditioning. As such, it will facilitate the discovery of novel genetic and molecular components within these remarkable pathways, paving the way for therapies that exploit the nervous system's intrinsic regenerative capability.