How Do Muller Glia Control Circuit-Specific Retinal Synaptogenesis?

穆勒胶质细胞如何控制特定电路的视网膜突触发生？

• 批准号: 9328930
• 负责人: Sehwon Koh
• 金额: $ 6.1万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9328930
• 关键词: Age related macular degeneration; Astrocytes; Binding; Biological Models; Blocking Antibodies; Brain; CARTPT gene; Calcium Channel; Cell Culture Techniques; Cells; Development; Doctor of Philosophy; Electron Microscopy; Enterobacteria phage P1 Cre recombinase; Excitatory Synapse; Eye diseases; Functional disorder; Glaucoma; Goals; Impairment; In Vitro; Inner Plexiform Layer; Integrins; Knock-out; Knockout Mice; LoxP-flanked allele; Maintenance; Methods; Molecular; Muller' s cell; Mus; Natural regeneration; Neuraxis; Neurodegenerative Disorders; Neuroglia; Neurons; Outcome; Pathway interactions; Pharmaceutical Preparations; Protein Family; Rattus; Retina; Retinal; Retinal Degeneration; Retinal Diseases; Retinal Ganglion Cells; Rodent; Role; Signal Transduction; Specificity; Subgroup; Sum; Synapses; Testing; Thrombospondin 1; Thrombospondins; Time; Transgenic Mice; Viral; Vision; Work; base; brain cell; cell type; cellular targeting; effective therapy; experimental study; gabapentin; gene therapy; insight; molecular targeted therapies; nervous system disorder; neural circuit; novel; novel therapeutics; promoter; receptor; repaired; small hairpin RNA; synaptogenesis; therapeutic target; thrombospondin 2

Synapses are the basic functional units of the central nervous system (CNS). Synaptic dysfunction and synapse loss are hallmarks of neurological disorders including retinal degeneration. However, there currently are no effective therapies that can repair or regenerate these synaptic impairments. Therefore, my long- term goal is to develop cell- and gene-based therapies to repair and/or regenerate these impaired synaptic circuits. In particular, I aim to identify novel cellular and molecular targets for the treatment of retinal degenerative diseases such as age-related macular degeneration and glaucoma. Recent studies have shown that glial cells are important regulators of synapse formation, maintenance and function in the brain. Particularly, astrocytes, major glia cell type in brain, secrete thrombospondin (TSP) family proteins that induce excitatory synapse formation. Unlike brain, Muller glia (MG) are the major glial cell type of the retina, however, how MG regulate neuronal connectivity in the retina remains unclear. In my preliminary experiments, I found that MG secretes TSP1 and TSP2 during early development of the retinal circuitry. TSP1, TSP2 and their synaptogenic receptor α2δ-1 are enriched in the outer and inner plexiform synaptic layers (OPL and IPL, respectively) of the retina. Transgenic mice lacking α2δ-1 (α2δ-1 KO) have dramatically decreased number of synapses in the IPL further supporting their involvements in retinal circuitry development. Particularly, TSP1 is specifically localized at two synaptic sublaminae within the IPL. In vitro studies using purified Retinal Ganglion Cell (RGC) cultures demonstrated that TSP1 specifically promotes synapse formation of On-Off Direction-Selective RGCs (ooDSGCs). TSP1-induced synaptogenesis is inhibited by a function-blocking antibody against Integrin β1, another known receptor of TSP1 that is enriched in ooDSGCs. On the other hand, TSP2 induces formation of synapses onto all RGCs. Based on these findings, I hypothesize that, in the retina, MG-secreted TSPs control different aspects of retinal excitatory synapse development through their common receptor α2δ-1. I further postulate that TSP1 regulates formation of ooDSGCs connectivity through an interaction with Integrin β1 which confers circuit specificity. To test these hypotheses, here I propose two specific aims; 1) To determine the requirement of MG-secreted TSP1 and 2 and their common synaptogenic receptor α2δ-1 for retinal synapse development and function. 2) To determine the role of TSP1/Integrin β1 interaction for the formation of On-Off DSGC specific circuitry. The proposed studies would provide a significant step forward in our understanding of how MG control retinal synaptic development in a circuit specific manner and also would facilitate development of novel therapeutic strategy to repair impaired synaptic circuits. !

突触是中枢神经系统的基本功能单位。突触功能障碍和 突触丧失是包括视网膜变性在内的神经系统疾病的标志。然而，目前 目前还没有有效的治疗方法可以修复或再生这些突触损伤。因此，我的长期- 长期目标是开发基于细胞和基因的疗法来修复和/或再生这些受损的突触， 电路.特别是，我的目标是确定新的细胞和分子靶点，用于治疗视网膜病变。 老年性黄斑变性和青光眼等退行性疾病。 最近的研究表明，神经胶质细胞是突触形成、维持和分化的重要调节因子。 在大脑中的功能。特别地，星形胶质细胞，脑中的主要神经胶质细胞类型，分泌血小板反应蛋白（TSP）家族 诱导兴奋性突触形成的蛋白质。与脑不同，Muller胶质细胞（MG）是主要的神经胶质细胞类型。 然而，MG如何调节视网膜中的神经元连接仍然不清楚。在我 初步的实验，我发现MG分泌TSP 1和TSP 2在早期发展的视网膜 电路TSP 1、TSP 2和它们的突触受体α2δ-1在外丛状和内丛状中富集 视网膜的突触层（分别为OPL和IPL）。缺乏α2δ-1（α2δ-1 KO）的转基因小鼠具有 IPL中的突触数量急剧减少，进一步支持它们参与视网膜回路 发展特别地，TSP 1特异性地定位于IPL内的两个突触亚板层。体外 使用纯化的视网膜神经节细胞（RGC）培养物的研究表明，TSP 1特异性地促进 开-关方向选择性RGCs（ooDSGCs）的突触形成。TSP 1诱导的突触发生被抑制 通过针对整合素β1的功能阻断抗体，整合素β1是另一种已知的富含 ooDSGCs。另一方面，TSP 2诱导在所有RGC上形成突触。 基于这些发现，我假设，在视网膜中，MG分泌的TSP控制视网膜的不同方面， 兴奋性突触通过它们共同的受体α2δ-1发育。我进一步假设TSP 1调节 通过与整合素β1的相互作用形成ooDSGCs连接，整合素β1赋予回路特异性。到 为了验证这些假设，我提出了两个具体目标：1）确定MG分泌的需求 TSP 1和TSP 2及其共同的突触发生受体α2δ-1在视网膜突触发育中的作用， 功能2)确定TSP 1/整合素β1相互作用在形成On-Off DSGC中的作用 具体电路。拟议中的研究将为我们理解如何实现这一目标迈出重要一步。 MG以回路特异性方式控制视网膜突触发育，并且还将促进 新的治疗策略来修复受损的突触回路。 !