Maturation and Maintenance of the Postsynaptic Apparatus

突触后装置的成熟和维护

• 批准号: 7464227
• 负责人: JOSHUA R SANES
• 金额: $ 29.23万
• 依托单位: HARVARD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7464227
• 关键词: Acetylcholine; Actins; Adult; Agrin; Architecture; Autistic Disorder; Behavior Disorders; Birth; Brain; Cholinergic Receptors; Chromosome Pairing; Complex; Computer information processing; Condition; Defect; Development; Dystrophin; Elements; Embryo; Engineering; Environment; Event; Foundations; Genes; Glycoproteins; Homeostasis; Image; In Vitro; Intramuscular; Label; Life; Link; Lipids; Maintenance; Mediator of activation protein; Membrane; Metabolic; Microtubules; Molecular; Motor Neurons; Mus; Muscle Fibers; Mutagenesis; Mutant Strains Mice; Nerve; Nervous system structure; Neuraxis; Neurologic; Neuromuscular Junction; Neurons; Neurotransmitters; Pathway interactions; Phosphorylation; Postsynaptic Membrane; Preparation; Process; Property; Protein Isoforms; Proteins; Proteoglycan; Public Health; Role; Schwann Cells; Shapes; Signal Transduction; Signaling Molecule; Site; Skeletal system; Solid; Structure; Synapses; Synaptic Cleft; System; Testing; Time; Tyrosine Phosphorylation; Work; addiction; alpha-dystrobrevin; cell cortex; critical developmental period; dystrobrevin; fluorophore; in vivo; nerve supply; novel; peripheral membrane protein 43K; postnatal; postsynaptic; receptor; scaffold; size; synaptic function; synaptogenesis; trafficking

DESCRIPTION (provided by applicant): Pre- and postsynaptic elements exchange developmentally important signals as synapses form. The simplicity, size and accessibility of the skeletal neuromuscular junction (NMJ) make it an excellent preparation for studying these signals and the intracellular signal transduction mechanisms they use. We and others previously defined a rudimentary pathway for initial steps of postsynaptic differentiation at the NMJ in which the proteoglycan z-agrin is a nerve-derived signal, MuSK is its main receptor, and rapsyn is a critical intracellular effector leading to aggregation of acetylcholine receptors. We will now build on this foundation to analyze the dramatic alterations that transform the postsynaptic apparatus at the embryonic NMJ during early postnatal life. These include topological remodeling of the ovoid plaque to a complex pretzel-shaped array of branches; alterations in molecular architecture; subdivision of the membrane into distinct domains; and changes in biophysical properties and metabolic stability. Using a novel culture system in which the plaque to pretzel transition occurs aneurally, we will analyze ways in which two main nerve-derived signals, agrin and acetylcholine, shape the postsynaptic membrane. Using newly generated conditional mutant mice, we will determine whether agrin is required not only for the formation of NMJs but also for their maturation or maintenance. Using targeted mutagenesis in vivo and time-lapse imaging of cultured myotubes, we will analyze roles of lpha-dystrobrevin and LL5_, two synapse-associated proteins that we have already implicated in postsynaptic maturation. Together, these studies on key transsynaptic signals (agrin and neurotransmitter) and intracellular mediators (alpha-dystrobrevin and LL5_) will provide a framework for understanding how postsynaptic maturation occurs and how it is regulated. Importantly, all of these components are present at central synapses, so results will directly enhance our understanding of synaptic remodeling in the postnatal brain. Such remodeling has been studied intensively, because it underlies plasticity during the critical period and in adults, and because defects in processes that regulate it seem likely to underlie conditions as diverse as autism and addiction. Studies of early events in synapse formation at the NMJ have already informed our understanding of less accessible neuron-neuron synapses, and we believe that studies of synaptic maturation and maintenance will be equally broadly applicable. PUBLIC HEALTH RELEVANCE: Nerve cells communicate with each other at junctions called synapses. Synapses are the sites of information processing and plasticity in the normal nervous system, and the sites of defects believed to underlie many neurological and behavioral disorders. Many of the early steps in synapse formation have been described over the past several years, but less is known about how the initially-formed synapse is remodeled during postnatal maturation. We propose to study these processes at the skeletal neuromuscular junction (NMJ). The simplicity, size and accessibility of this synapse make it an excellent preparation for studying signals that regulate synaptic maturation and the intracellular signal transduction mechanisms they use. Moreover, dramatic alterations transform the postsynaptic apparatus at the embryonic NMJ during early postnatal life. These include topological remodeling of the ovoid plaque to a complex pretzel-shaped array of branches; alterations in molecular architecture; subdivision of the membrane into distinct domains; and changes in biophysical properties and metabolic stability. Specifically, we will use the NMJ to analyze roles of two nerve-derived signals, agrin and acetylcholine, and two intramuscular signaling molecules, alpha-dystrobrevin and LL5_, all of which have already been implicated in postsynaptic development. Using a novel culture system in which the plaque to pretzel transition occurs aneurally, we will analyze how these molecules shape the postsynaptic membrane. Hypotheses derived from these studies will be tested using genetically engineered mutant mice. Importantly, all of these components are present at central synapses, so results will directly enhance our understanding of synaptic remodeling in the postnatal brain. Such remodeling has been studied intensively, because it underlies plasticity during the critical period and in adults, and because defects in processes that regulate it seem likely to underlie conditions as diverse as autism and addiction. Studies of early events in synapse formation at the NMJ have already informed our understanding of less accessible neuron-neuron synapses, and we believe that studies of synaptic maturation and maintenance will be equally broadly applicable.

描述（由申请人提供）：突触前和后元素交换为突触形式发育重要的信号。骨骼神经肌肉连接（NMJ）的简单性，大小和可及性使其成为研究这些信号和它们使用的细胞内信号转导机制的绝佳准备。我们和其他人先前以前定义了一种基本途径，用于在NMJ处进行突触后分化的初始步骤，其中蛋白聚糖Z-Gagrin是神经衍生的信号，Musk是其主要受体，Rapsyn是一种关键的细胞内效应子，导致乙酰胆碱受体聚集。现在，我们将建立在这个基础的基础上，以分析产后早期生活期间胚胎NMJ的突触后仪器的戏剧性变化。这些包括将卵形斑块拓扑重塑为复杂的椒盐脆饼形阵列；分子体系结构的改变；将膜细分分为不同的领域；以及生物物理特性和代谢稳定性的变化。使用一种新型的培养系统，在该系统中，斑块向椒盐脆饼过渡发生动脉尿道，我们将分析两个主要神经源性信号Agrin和乙酰胆碱的方法，形成突触后膜。使用新生成的条件突变小鼠，我们将确定不仅需要形成NMJ，而且还需要其成熟或维持。我们将使用靶向诱变和培养的肌管的延时成像，我们将分析我们已经与突触后成熟有关的LPHA-Dystrobrevin和LL5_的作用，这是两个与突触相关的蛋白。共同，这些对关键的透射信号（Agrin和神经递质）和细胞内介体（alpha-dystrobrevin和ll5_）的研究将提供一个框架，以了解如何发生突触后成熟以及如何调节。重要的是，所有这些成分都存在于中央突触中，因此结果将直接增强我们对产后大脑突触重塑的理解。这种重塑已经进行了深入研究，因为它是在关键时期和成年人中可塑性的基础，并且因为调节过程中的缺陷似乎是自闭症和成瘾等各种条件的基础。对NMJ突触形成的早期事件的研究已经为我们对较不访问的神经元神经元突触的理解提供了信息，我们认为，突触成熟和维持的研究将同样广泛地适用。公共卫生相关性：神经细胞在称为突触的连接处相互通信。突触是正常神经系统中信息处理和可塑性的部位，并且被认为是许多神经系统和行为障碍的缺陷部位。在过去的几年中，已经描述了突触形成的许多早期步骤，但是关于在产后成熟期间如何重塑最初形成的突触。我们建议在骨骼神经肌肉连接（NMJ）上研究这些过程。这种突触的简单性，大小和可及性使其成为研究调节突触成熟和它们使用的细胞内信号转导机制的信号的绝佳准备。此外，戏剧性的改变会改变产后早期胚胎NMJ的突触后设备。这些包括将卵形斑块拓扑重塑为复杂的椒盐脆饼形阵列；分子体系结构的改变；将膜细分分为不同的领域；以及生物物理特性和代谢稳定性的变化。具体而言，我们将使用NMJ分析两个神经衍生信号的作用，即Agrin和乙酰胆碱，以及两个肌内信号分子，Alpha-Dystrobrevin和LL5_，它们已经与后突触后发育有关。使用一种新型的培养系统，在该系统中，斑块到椒盐脆饼过渡的发生，我们将分析这些分子如何塑造突触后膜。从这些研究中得出的假设将使用基因工程突变小鼠进行测试。重要的是，所有这些成分都存在于中央突触中，因此结果将直接增强我们对产后大脑突触重塑的理解。这种重塑已经进行了深入研究，因为它是在关键时期和成年人中可塑性的基础，并且因为调节过程中的缺陷似乎是自闭症和成瘾等各种条件的基础。对NMJ突触形成的早期事件的研究已经为我们对较不访问的神经元神经元突触的理解提供了信息，我们认为，突触成熟和维持的研究将同样广泛地适用。