Connexins and electrical synapses in the retina

视网膜中的连接蛋白和电突触

• 批准号: 8038927
• 负责人: DAVID L PAUL
• 金额: $ 42.25万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8038927
• 关键词: Address; Amacrine Cells; Antibodies; Blindness; Cells; Connexins; Coupling; Darkness; Data; Detection; Disease; Dyes; Electrical Synapse; Gap Junctions; Genetic; Glycine; Human; Injection of therapeutic agent; Knock-out; Life; Light; Measurement; Methods; Microelectrodes; Modeling; Monkeys; Movement; Mus; Neural Retina; Oryctolagus cuniculus; Pathway interactions; Physiological; Proteins; Recombinant adeno-associated virus (rAAV); Retina; Retinal; Retinal Cone; Signal Pathway; Signal Transduction; Synapses; Testing; Therapeutic; Tissues; Tracer; Transgenic Mice; Transgenic Organisms; Vertebrate Photoreceptors; base; ganglion cell; glycine transporter; neural circuit; neurobiotin; novel; prevent; research study; response; retinal rods; segregation; subretinal injection

DESCRIPTION (provided by applicant): A compelling body of evidence indicates that signals from rod photoreceptors use multiple pathways to reach ganglion cells. In the canonical primary pathway, rod signals gain access to downstream cone circuitry through the AII amacrines which form electrical synapses (gap junctions) with ON cone bipolar and glycinergic synapses with OFF cone bipolar. In the secondary pathway, electrical synapses between rods and cones provide a direct entry for rod signals into cone circuits. However, a credible direct demonstration of rod-cone coupling has been made only in monkey. Because technical issues prevent a conventional approach to measurement of rod-cone coupling in the mouse (i.e. injections of junction-permeant tracers using microelectrodes), we developed a novel method to evaluated coupling. The method is based on transgenic, cell-specific expression of a transporter, the movement of the transported molecule through gap junctions to neighboring cells and the detection of that molecule with specific antibodies. This method eliminates the need for any physical manipulation of the live cells. Despite the widely held assumption that rod-cone coupling underlies the secondary pathway, we found no evidence of rod-cone coupling in the mouse. Thus, we propose a set of experiments to determine the generality of the canonical secondary pathway model by testing rod-cone coupling in the rabbit and to evaluate cone-cone and possible rod-rod coupling in mouse and rabbit retinas. In contrast, our data strongly support the basic tenets of the rod primary pathway. However, while the prevailing model postulates that AII amacrines express Cx36 and cone ON bipolar express Cx45, forming a 'heterotypic' electrical synapse, our data indicate more complexity. We propose there are two types of glycinergic amacrine cells, those expressing Cx45 and those expressing Cx36 and that each forms homotypic junctions with a subset of cone bipolar cells expressing the same connexin. We hypothesize that the expression of incompatible connexins is mechanism to allow segregation of amacrine- cone bipolar interactions according to cell subtype. We will determine the types of cone bipolar involved in rod primary pathway signaling and which connexins they employ. In addition, we will determine if different retinal connexins can functionally interact. PUBLIC HEALTH RELEVANCE: Our studies address fundamental questions about the neural circuitry employed by rod photoreceptors, which contribute to retinal responses over a range of light inputs from near total darkness to bright moonlight. Disorders of the neural retina are a primary cause of human blindness and a rational pursuit of therapeutic strategies requires a full understand of mammalian retinal circuitry.

描述（由申请人提供）：令人信服的证据表明，来自Rod光感受器的信号使用多个途径到达神经节细胞。在规范初级途径中，杆信号通过AII amacrine访问下游锥电路，并在锥双极性和糖胶质突触上形成电气突触（间隙连接），并带有OFF锥双极性。在次级途径中，杆和锥之间的电气突触为杆信号直接进入锥电路。但是，仅在猴子中进行了可靠的直接演示。由于技术问题阻止了一种常规的方法来测量小鼠中的杆孔耦合（即使用微电极对接线 - 佩里特示踪剂的注射），因此我们开发了一种新的方法来评估耦合。该方法基于转运蛋白的转基因，细胞特异性表达，转运分子通过间隙连接到相邻细胞的运动以及用特定抗体检测该分子。这种方法消除了对活细胞进行任何物理操作的需求。尽管人们普遍认为，杆孔耦合是次级途径的基础，但我们没有发现小鼠中杆孔耦合的证据。因此，我们提出了一组实验，以通过测试兔子中的杆孔耦合并评估小鼠和兔视网膜中的锥形杆孔和可能的杆rod耦合来确定规范次级途径模型的通用性。相比之下，我们的数据强烈支持杆主要途径的基本原则。但是，尽管流行的模型假设AII Amacrines在双极快递CX45上表达CX36和锥形，形成了“异型”电气突触，但我们的数据表明更复杂。我们提出有两种类型的甘氨酸链氨酸酯细胞，即表达CX45和表达CX36的甘霉素细胞，并且每种甘氨酸细胞都形成同型连接，并具有表达相同连接素的锥双极细胞的子集。我们假设不兼容连接素的表达是允许根据细胞亚型分离枝糖锥双极相互作用的机制。我们将确定参与Rod主途径信号传导以及它们采用哪些连接素的锥双极的类型。另外，我们将确定不同的视网膜连接素是否可以在功能上相互作用。 公共卫生相关性：我们的研究涉及有关Rod光感受器使用的神经回路的基本问题，这些问题有助于视网膜反应，从近乎完全黑暗到明亮的月光下的一系列光输入。神经视网膜的疾病是人类失明的主要原因，对治疗策略的合理追求需要充分了解哺乳动物视网膜电路。