Identification of Axon and Dendrite Regeneration Antagonists in Drosophila

描述（由申请人提供）：对中枢神经系统的损害是毁灭性的，使人衰弱。对于严重的中枢神经系统损伤，目前尚无有效的临床治疗方法。根据2008年的一项研究（里夫基金会，“一度分离”），瘫痪影响了大约550万美国人。对神经元为什么不能在损伤部位再生的研究已经产生了一些见解。然而，迄今为止发现的阻止再生的因素只能解释为什么没有恢复的一小部分原因。为了开发有效的治疗方法，我们需要更全面地了解外在和内在的再生拮抗剂。我们的实验室最近开发了一种系统，它使用双光子激光来切割苍蝇神经元的轴突或树突投影。损伤后，我们观察到这些突起的退变和随后的再生。果蝇树突树突（da）神经元的再生与哺乳动物系统的再生具有许多重要特征，并允许公正地发现影响这一过程的基因。我的目标是用这个系统来提出关于轴突和树突再生的基本问题。(1)即使在同样的环境中，某些神经元具有再生能力，而其他细胞却没有，这其中的内在差异是什么？类似种类的数据神经元表现出不同的再生能力。我们知道转录因子定义了这些细胞类型的特征，包括树突树突化、轴突靶向和受体表达的模式。这些转录因子是否也决定了再生能力的差异，通过什么机制？(2)神经胶质细胞的外部信号如何调节轴突再生的发生？神经胶质细胞在损伤后变性过程中吞噬神经突碎片。我们将描述胶质细胞在再生中的作用，并检查可能调节底物是否允许轴突生长的胶质信号。神经元内部和周围组织的信号在多大程度上共同调节再生？(3)我们可以识别和验证哪些新的再生拮抗剂？在筛选新的再生调节因子后，我们将研究确定的拮抗剂是否是已知或独特途径的组成部分。有了这些问题的答案，我们将能够更好地解释为什么神经元再生失败，并更有效地设计治疗损伤的方法。我的研究生经历为使用遗传学和影像学检查神经系统提供了坚实的基础，这里提出的实验代表了在激励和支持的环境中进行个人训练和发现的重要机会。

DESCRIPTION (provided by applicant): Damage to the central nervous system is devastating and debilitating. There are no effective clinical treatments for serious central nervous system damage. Paralysis affects ~5.5 million Americans, according to a study in 2008 (Reeve Foundation, "One Degree of Separation"). Research into why neurons can't regrow across injury sites has yielded some insight. Yet the regeneration-preventing factors identified thus far only explain a small part of why there is no recovery. To develop effective therapies, we need a more comprehensive understanding of extrinsic and intrinsic regeneration antagonists. Our lab has recently developed a system that uses a two-photon laser to cut either the axon or dendrite projections of neurons in flies. After injury, we observe the degeneration of these projections and any subsequent regeneration. Regeneration in the dendritic arborization (da) neurons in flies shares a number of important characteristics with regeneration in mammalian systems, and allows unbiased discovery of genes that influence this process. I aim to use this system to ask fundamental questions about axonal and dendritic regeneration. (1) What are the intrinsic differences that allow some neurons to have the capacity to regenerate when other cells do not, even in the same permissive environment? Similar classes of well-described da neurons show distinct regenerative capacities. We know transcription factors that define the characteristics of these cell types, including the pattern of dendritic arborization, axonal targeting, and receptor expression. Do these transcription factors also define regenerative ability differences, and by what mechanism? (2) How do external cues from glial cells regulate whether axon regeneration occurs? Glial cells engulf neurite fragments during degeneration after damage. We will characterize the role of glia in regeneration, and examine glial signals that may regulate whether a substrate is permissive for axon growth. To what extent do signals inside the neuron and in the surrounding tissue combine to regulate regeneration? (3) What novel antagonists of regeneration can we identify and validate? After screening for novel regulators of regeneration, we will investigate whether identified antagonists are components of known or unique pathways. With answers to these questions, we will be able to better explain why neuron regeneration fails and more effectively design ways to treat injury. My graduate experience provides a solid foundation for examining the nervous system using genetics and imaging, and the experiments proposed here represent significant opportunities for personal training and discovery in a stimulating and supportive environment.