Development and Plasticity of a Retinotectal System

视网膜顶盖系统的发育和可塑性

基本信息

批准号：
8215691
负责人：
MU-MING POO
金额：
$ 31.33万
依托单位：
UNIVERSITY OF CALIFORNIA BERKELEY
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-08-01 至 2012-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8215691
关键词：
Acute Address Affect Axon Binding Biological Models Brain Cell surface Cells Chimeric Proteins Code Dendrites Development Dynamin Electroporation Endocytosis EphB2 Receptor Ephrin-B1 Exhibits Genetic Programming Glutamate Receptor Health Imaging Techniques Individual Lateral Light Long-Term Depression Long-Term Potentiation Medial Mediating Methods Molecular Monitor Mutate N-Methylaspartate Nervous system structure Neurons Perfusion Process Property Proteins Protocols documentation Recruitment Activity Recycling Regulation Relative (related person)Retinal Ganglion Cells Role Sensory Signal Transduction Stimulus Synapses Synaptic Vesicles System Tadpoles Tectum Mesencephali Testing Tetracyclines Time Transgenic Organisms Visual Whole-Cell Recordings Work Xenopus Xenopus laevis axon guidance base conditioning experience in vivo malformation mutant neural circuit optical imaging postsynaptic presynaptic protein expression receptive field relating to nervous system response retinotectal superior colliculus Corpora quadrigemina synaptic function visual stimulus

项目摘要

DESCRIPTION (provided by applicant): The retinotectal system of Xenopus laevis is used as a model system for studying the development of topographically ordered projections in the nervous system. Using in vivo electrophysiological recording and optical imaging techniques, together with molecular manipulations of cellular signaling, we propose to examine the role of cell surface-bound axon guidance molecules ephrin-B1 and EphB2 in regulating the maturation and plasticity of retinotectal synapses after the axons of retinal ganglion cells (RGCs) have made functional synaptic contacts with their targeted tectal cells. The proposed studies are based on our preliminary findings that perturbation of ephrin-B1 reverse signaling in the RGCs affects the maturation of synaptic functions, the dynamics of RGC axon arbors, and the magnitude of activity-induced long-term potentiation (LTP) of retinotectal synapses. In the present project, we propose to further examine the contribution of both ephrin-B1 reverse signaling and EphB2 forward signaling in regulating the maturation and plasticity of retinotectal connections and to determine how this regulation contributes to developmental and visual experience-driven refinement of the receptive field (RF) properties of tectal cells. Selective manipulations of ephrin-B1 and EphB2 signaling will be performed to dissect the modulatory effects of ephrin-B1 vs. EphB2 signaling, by using three different methods, either alone or in combination: (1) acute perfusion of the tectum with the ectodomain fusion protein EphB2-Fc or ephrin-B1-Fc, (2) expression of wild-type or mutated forms of Ephrin-B1 or EphB2 in a few RGCs or tectal cells by electroporation, and (3) global tetracycline-induced transgenic expression of these proteins in either all presynaptic RGCs or all postsynaptic tectal cells. In Aim 1, we will examine the relative contribution of ephrin-B1 reverse signaling and EphB2 forward signaling to the maturation of synaptic functions, identify the pre- and postsynaptic loci of modulation by ephrin-B1/EphB2 signaling, and test the involvement of dynamin-dependent endocytosis and glutamate receptor recruitment in pre- and postsynaptic modulation, respectively. In Aim 2, we will examine the contribution of ephrin-B1/EphB2 signaling to the modulation of LTP and long-term depression (LTD), the postsynaptic mechanisms underlying such modulation, and the role of ephrin-B1/EphB2 signaling in modulating the arbor dynamics of both RGC axons and tectal cell dendrites. In Aim 3, we will examine whether ephrin-B1/EphB2 signaling contributes to the developmental reduction of the RF size, the progressive matching of excitatory and inhibitory RFs, and visual experience- induced direction selectivity in the tectal cell responses to visual stimuli. Together, these in vivo studies offer unique opportunities to address the function of an important set of axon guidance molecules in regulating synapse maturation and plasticity, and to understand the role of trans-synaptic molecular signaling in developmental and experience-driven refinement of neural circuits. PUBLIC HEALTH RELEVANCE: Brain development depends critically on the timely maturation of synaptic connections, a process known to be regulated by both molecular factors coded by the genetic program and neural activities triggered by sensory experience. This project focuses on the function of an important set of molecular factors, ephrin-B1 and EphB2 receptor, in regulating the maturation of neural circuits. Results from the proposed studies will shed light on the mechanisms underlying normal neural circuit development and the potential causes of malformation of neural circuits during development.

描述（由申请人提供）：非洲爪蟾的视网膜顶盖系统被用作研究神经系统中拓扑有序投射的发展的模型系统。利用体内电生理记录和光学成像技术，结合细胞信号传导的分子操作，我们建议检查细胞表面结合的轴突引导分子 ephrin-B1 和 EphB2 在调节视网膜顶盖突触的成熟和可塑性中的作用。视网膜神经节细胞（RGC）已与其目标顶盖细胞建立功能性突触接触。拟议的研究基于我们的初步发现，即 RGC 中 ephrin-B1 反向信号传导的扰动会影响突触功能的成熟、RGC 轴突乔木的动态以及活动诱导的视网膜顶盖长期增强 (LTP) 的程度突触。在本项目中，我们建议进一步研究 ephrin-B1 反向信号传导和 EphB2 正向信号传导在调节视网膜顶盖连接的成熟和可塑性中的贡献，并确定这种调节如何有助于接受性的发育和视觉体验驱动的细化。顶盖细胞的场（RF）特性。将通过单独或组合使用三种不同的方法，对 ephrin-B1 和 EphB2 信号传导进行选择性操作，以剖析 ephrin-B1 与 EphB2 信号传导的调节作用：(1) 使用胞外域融合对顶盖进行急性灌注蛋白 EphB2-Fc 或 ephrin-B1-Fc，(2) Ephrin-B1 的野生型或突变形式的表达或通过电穿孔在一些 RGC 或顶盖细胞中表达 EphB2，以及 (3) 在所有突触前 RGC 或所有突触后顶盖细胞中全面四环素诱导这些蛋白质的转基因表达。在目标 1 中，我们将检查 ephrin-B1 反向信号传导和 EphB2 正向信号传导对突触功能成熟的相对贡献，确定 ephrin-B1/EphB2 信号传导调节的突触前和突触后位点，并测试动力蛋白的参与分别在突触前和突触后调节中依赖于内吞作用和谷氨酸受体募集。在目标 2 中，我们将研究 ephrin-B1/EphB2 信号传导对 LTP 和长期抑郁 (LTD) 调节的贡献、这种调节背后的突触后机制，以及 ephrin-B1/EphB2 信号传导在调节 LTP 和长期抑郁 (LTD) 中的作用。 RGC 轴突和顶盖细胞树突的乔木动力学。在目标 3 中，我们将检查 ephrin-B1/EphB2 信号传导是否有助于 RF 大小的发育减小、兴奋性和抑制性 RF 的逐步匹配，以及顶盖细胞对视觉刺激反应中视觉体验诱导的方向选择性。总之，这些体内研究提供了独特的机会来解决一组重要的轴突引导分子在调节突触成熟和可塑性方面的功能，并了解跨突触分子信号传导在神经回路的发育和经验驱动的细化中的作用。公共健康相关性：大脑发育关键取决于突触连接的及时成熟，这一过程已知受到遗传程序编码的分子因素和感官体验触发的神经活动的调节。该项目重点研究一组重要分子因子（ephrin-B1 和 EphB2 受体）在调节神经回路成熟中的功能。拟议研究的结果将揭示正常神经回路发育的机制以及发育过程中神经回路畸形的潜在原因。