Mechanisms of the recognition of degenerating dendrites

退化树突的识别机制

• 批准号: 9213943
• 负责人: Chun Han
• 金额: $ 34.48万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9213943
• 关键词: Address; Afferent Neurons; Anabolism; Apoptotic; Autoimmunity; Binding Proteins; Biological Assay; Biological Models; Candidate Disease Gene; Caspase; Cell membrane; Cells; Clustered Regularly Interspaced Short Palindromic Repeats; Color; Data; Dendrites; Development; Drosophila genus; Eating; Epithelial Cells; Extracellular Domain; Failure; Family; Family member; Future; Gene Deletion; Genetic; Human; Image; In Vitro; Inflammation; Injury; Insecta; Investigation; Larva; Lead; Life; Maintenance; Mammals; Masks; Mediating; Methodology; Monitor; Nerve Degeneration; Nervous system structure; Neurites; Neurodegenerative Disorders; Neuronal Injury; Neurons; Pathway interactions; Phagocytes; Phosphatidylserines; Process; Proteins; Reagent; Regulation; Reporter; Role; Sensory; Signal Transduction; Surface; System; Testing; Tissues; Vertebrates; Work; abstracting; in vivo; in vivo Model; innovation; loss of function; macrophage; membrane activity; neural circuit; neuroinflammation; novel; overexpression; prevent; receptor; repaired; sensor; spatiotemporal; wasting

Project Summary/Abstract Local degeneration of neuronal processes is an important mechanism in neural circuit remodeling and neuronal injury. The neuronal debris resulting from degeneration must be promptly cleared by phagocytes to prevent inflammation and to facilitate the subsequent neuronal regrowth. Although aberrant recognition and clearance of neuronal debris are implicated in neuroinflammation, autoimmunity, and neurodegenerative diseases, it is unknown how phagocytes distinguish degenerative neurites from surrounding healthy ones. In particular, three important questions remain unanswered: what is the signal on degenerating neurites that allows the recognition by phagocytes? What is the receptor for the recognition signal of degenerating neurites? How is the recognition signal specifically exposed on degenerating neurites? Our new in vivo data provided important clues that will help us to solve these puzzles. Using our new in vivo probes, we discovered that the ‘eat-me’ signal phosphatidylserine (PS) is absent on the surface of healthy dendrites but is exposed on degenerating dendrites in both developmental remodeling and physical injury. Building on these observations, this project aims to elucidate the in vivo mechanisms of PS exposure and recognition in dendrite degeneration using Drosophila sensory neurons as a model system. Our long term objective is to uncover autonomous and non-autonomous mechanisms of dendrite degeneration and repair. For this project, we propose the following three aims: 1) Determine the role of PS exposure in the recognition and engulfment of degenerating dendrites. The necessity of PS exposure in engulfment of dendrites after injury will be determined by (i) masking PS on the dendrite surface with PS-binding proteins, and (ii) blocking the biosynthesis of PS in specific neurons. The sufficiency of PS in triggering dendrite engulfment and degeneration will be tested by ectopically inducing PS exposure in neurons. 2) Investigate how the CED-1 family member Draper recognizes degenerating dendrites. Our results suggest that Draper recognizes degenerating dendrites. Two complementary in vivo competition assays will be performed to determine if Draper directly interacts with PS. 3) Determine how PS exposure is regulated in neurons and degenerating dendrites. By conducting loss-of-function studies of candidate genes, the identities of PS flippases and scramblases that regulate PS exposure during dendrite degeneration will be determined. The role of caspases in PS exposure will be investigated by examining caspase activity after dendrite injury and by disrupting the caspase pathway in neurons. Together, these aims will reveal in vivo mechanisms of neuronal debris sensing. As the clearance of neuronal debris in both mammals and insects requires the same CED-1 family of engulfment receptor, this study will reveal conserved mechanisms that may be relevant to neurodegenerative disorders.

项目摘要/摘要 神经元过程的局部变性是神经元回路重塑和 神经元损伤。吞噬细胞必须立即清除因变性而产生的神经元调试 防止炎症并促进随后的神经元改革。虽然认可和 神经元碎屑的清除含量在神经炎症，自身免疫性和神经退行性中隐含 疾病，未知吞噬细胞如何将退化性神经与周围健康的神经区分开。 特别是，三个重要的问题仍未得到解答：变性神经的信号是什么？ 允许吞噬细胞识别？识别神经变性的识别信号的受体是什么？ 识别信号如何专门暴露于退化的神经运动中？我们提供的新的体内数据 重要的线索将帮助我们解决这些难题。使用我们的新体内问题，我们发现 “饮食”信号磷脂酰丝氨酸（PS）在健康的树突表面不存在，但暴露在 在发育重塑和身体损伤中退化的树突。以这些观察为基础 该项目旨在阐明Dendrite中PS暴露和识别的体内机制 使用果蝇感觉神经元作为模型系统的退化。我们的长期目标是发现 树突变性和修复的自主和非自主机制。对于这个项目，我们 提案以下三个目标：1）确定PS暴露在识别和吞噬中的作用 退化的树突。受伤后吞没在树突中的PS暴露的必要条件是 通过（i）用PS结合蛋白在树突表面掩盖PS，以及（ii）阻止 特定神经元中PS的生物合成。 PS在触发树突吞没和 退化将通过生态诱导神经元的PS暴露来测试。 2）研究CED-1如何 家庭成员Draper识别退化的树突。我们的结果表明，德雷珀认识 退化的树突。将执行两次完整的体内竞赛测定法，以确定是否是否 Draper直接与PS相互作用。 3）确定如何在神经元中调节PS暴露 退化的树突。通过进行候选基因的功能丧失研究，PS的身份 将确定调节在树突变性过程中调节PS暴露的Flippase和Scyblase。这 胱天蛋白酶在PS暴露中的作用将通过检查树突损伤后的caspase活动和 破坏神经元中的caspase途径。这些目标在一起将揭示神经元的体内机制 碎片感应。由于哺乳动物和昆虫中神经元碎片的清除均需要相同的CED-1 吞噬受体家族，这项研究将揭示可能与 神经退行性疾病。