C. elegans model for mammalian lesion-conditioned axon regeneration

描述（由申请人提供）：在美国，中枢神经系统（CNS）损伤每年折磨数百万人，缺乏有效的治疗方法。这类损伤后功能恢复的一个基本障碍是中枢神经系统再生能力弱。神经治疗学中最令人兴奋的发现之一是，如果外周感觉轴突发生条件反射损伤，哺乳动物神经元可以强烈地将其中央轴突再生到损伤部位内外。确定病变条件反射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难驾驭性阻碍了理解病变条件的进展，但在更简单的、遗传易处理的生物体中建立病变条件模型可能会取得快速突破。小蛔虫秀丽隐杆线虫是一种非常有用的模式生物，具有无与伦比的遗传可操作性。在20世纪90年代末，秀丽隐杆线虫的研究人员注意到，几个神经元的电活动因突变而停止，它们长出了异位轴突。利用先进的激光手术技术解剖完整的成年秀丽隐杆线虫的单个神经元，我们观察到这些相同的感觉神经元中存在强烈的病变调节效应。最近发表的数据表明，在哺乳动物损伤调节中抑制电活动，以及我们的再生实验与之前秀丽隐杆线虫异位生长的研究之间的相似性表明，所有这些过程都是高度相关的，并且共享遗传途径。本研究的目的是建立秀丽隐杆线虫的异位生长，作为哺乳动物病变调节的遗传可处理模型。目的1的实验将进一步证明和表征我们在秀丽隐杆线虫中观察到的刺激异位生长和病变调节效应的神经元活动的减少。结果有望将活性降低与轴突再生联系起来，并进一步确定活性在异位生长中的作用。目的2的实验旨在开发一种正向筛选，以鉴定介导异位轴突生长和病变条件再生的基因。该筛选将鉴定出在秀丽隐杆线虫中抑制异位轴突生长和轴突再生的新基因，以及在高等动物中介导病变调节的同源哺乳动物基因。通过开发病变调节的遗传可处理模型，这些研究将为加速和变革性研究奠定基础，这些研究具有巨大的潜力，可以阐明这一显著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。

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.