The Role of Gap Junctions in the Progressive Loss of Retinal Neurons in Glaucoma

间隙连接在青光眼视网膜神经元逐渐丧失中的作用

• 批准号: 9212812
• 负责人: Stewart Allen Bloomfield
• 金额: $ 40.5万
• 依托单位: STATE COLLEGE OF OPTOMETRY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-01 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9212812
• 关键词: Ablation; Amacrine Cells; Antibodies; Apoptosis; Behavioral; Biological Preservation; Blindness; Brain; Bystander Effect; Cell Death; Cells; Central Nervous System Diseases; Cessation of life; Connexins; Coupled; Data; Electrophysiology (science); Electroretinography; Elements; Experimental Models; Eye; Frequencies; Gap Junctions; Genetic; Glaucoma; Glycine; Glycyrrhetinic Acid; Goals; Injection of therapeutic agent; Injury; Ischemia; Knockout Mice; Label; Measures; Meclofenamic Acid; Mediating; Microelectrodes; Microspheres; Modeling; Movement; Mus; Necrosis; Neurodegenerative Disorders; Neurons; Optic Nerve; Pathway interactions; Permeability; Pharmacology; Physiologic Intraocular Pressure; Physiological; Physiology; Play; Property; Research; Retina; Retinal; Retinal Diseases; Retinal Ganglion Cells; Role; Secondary to; Signal Transduction; Supporting Cell; Synapses; Techniques; Testing; Therapeutic; Therapeutic Intervention; Tracer; Trauma; Vision; Visual evoked cortical potential; Visual impairment; Work; base; calretinin; cell type; cohort; connexin 36; excitotoxicity; experimental study; gamma-Aminobutyric Acid; intercellular communication; intravitreal injection; lucifer yellow; mouse model; multi-electrode arrays; neurobiotin; neuron loss; neuropathology; neuroprotection; novel; novel therapeutics; patch clamp; programs; public health relevance; receptive field; response; retinal neuron; targeted treatment; therapeutic target

 DESCRIPTION (provided by applicant): Glaucoma, the second leading cause of blindness worldwide, is a neurodegenerative disease often associated with elevated intraocular pressure (IOP) and characterized by the progressive loss of retinal ganglion cells (RGCs) leading to visual loss. Among the various types of cell death associated with neuropathologies, the major cellular pathways underlying apoptosis and necrosis have been well characterized. However, in addition to these intrinsic mechanisms underlying primary cell death, intercellular communication via gap junctions (GJs) appear to play a major, yet poorly understand, role in secondary or `bystander' cell death. GJs, proteins that form cytoplasmic bridges between neighboring cells, act as conduits by which toxic materials are passed from dying cells to their neighbors leading to their death. Studies in CNS suggest that progressive secondary cell death mediated by GJs may, in fact, account for the majority of cell death associated with a number of insults, including ischemia, excitotoxicity, and trauma. Consistent with these findings, our preliminary data in retina show that blockade or ablation of GJs can significantly reduce the loss of RGCs and amacrine cells (ACs) in experimental glaucoma. We therefore posit that GJ-mediated secondary cell death is a crucial mechanistic element of glaucomatous injury, resulting in the majority of RGC and amacrine cell (AC) loss, and thereby offers a novel target for neuroprotective treatment. To test this hypothesis, we propose to use mouse models of experimental glaucoma to show directly that pharmacological blockade of GJs or genetic ablation of their constituent connexin subunits results in a significant reduction in in the loss o RGCs and the ACs to which they are coupled. Different GJs, based on the composition of their connexins, can have selective permeabilities, suggesting that the makeup of a GJ may determine whether it promotes cell death following injury. We will therefore use knockout mice in which selective connexins are ablated to determine which GJ cohorts support cell loss in glaucoma and should thus be targeted to promote neuroprotection. Finally, we will carry out electrophysiological and behavioral experiments to assess whether increasing RGC and AC survivability in glaucoma by blocking GJs results in preservation of visual function. In these experiments, we will record the electroretinogram (ERG), and use patch-clamp and microelectrode array recording techniques to assess retinal function. We will also record visual evoked potentials (VEP) and measure the optokinetic response (OKR) to assess central visual function. The results of this study should elucidate a new and important mechanism of RGC degeneration associated with glaucoma and, in so doing, reveal a novel target for neuroprotective treatment. While the proposed work will be directed at glaucoma, the therapeutic strategies that emerge should be applicable to the treatment of neurodegenerative diseases seen in other parts of the CNS.

 描述（由申请人提供）：青光眼是全球第二大致盲原因，是一种神经退行性疾病，通常与眼内压（IOP）升高相关，特征为视网膜神经节细胞（RGC）进行性丧失，导致视力丧失。在与神经病理学相关的各种类型的细胞死亡中，细胞凋亡和坏死的主要细胞途径已经得到很好的表征。然而，除了这些内在机制的基础上的主要细胞死亡，通过间隙连接（GJs）的细胞间通信似乎发挥了重要的，但知之甚少，在继发性或“旁观者”细胞死亡的作用。GJ是在相邻细胞之间形成细胞质桥梁的蛋白质，它作为管道将有毒物质从垂死细胞传递到相邻细胞，导致它们死亡。CNS的研究表明，GJ介导的进行性继发性细胞死亡实际上可能是与许多损伤相关的大多数细胞死亡的原因，包括缺血、兴奋性毒性和创伤。与这些发现一致，我们在视网膜中的初步数据显示，GJ的阻断或消融可以显著减少实验性青光眼中RGC和无长突细胞（AC）的损失。因此，我们认为，GJ介导的继发性细胞死亡是一个至关重要的机械因素，导致大多数RGC和无长突细胞（AC）的损失，从而为神经保护治疗提供了一个新的目标。为了验证这一假设，我们建议使用实验性青光眼的小鼠模型来直接显示GJ的药理学阻断或其组成连接蛋白亚基的基因消融导致RGC和它们所偶联的AC的损失显著减少。基于其连接蛋白的组成，不同的GJ可以具有选择性渗透性，这表明GJ的组成可以决定它是否促进损伤后的细胞死亡。因此，我们将使用选择性连接蛋白被消融的基因敲除小鼠来确定哪些GJ队列支持青光眼中的细胞丢失，因此应该靶向促进神经保护。最后，我们将进行电生理学和行为学实验，以评估通过阻断GJ来增加青光眼中RGC和AC的存活率是否会导致视觉功能的保留。在这些实验中，我们将记录视网膜电图（ERG），并使用膜片钳和微电极阵列记录技术来评估视网膜功能。我们还将记录视觉诱发电位（VEP）和测量视动反应（OKR），以评估中枢视觉功能。这项研究的结果应该阐明与青光眼相关的RGC变性的一个新的和重要的机制，并在这样做，揭示了一个新的神经保护治疗的目标。虽然拟议的工作将针对青光眼，出现的治疗策略应适用于治疗中枢神经系统其他部位的神经退行性疾病。