The Dynamics of Synaptic Component at the Neuromuscular Junction of Living Animal

描述（由申请人提供）：我们的长期目标是更好地了解神经递质受体密度如何在体内成熟和发育中的突触中维持和调节。我们使用神经肌肉接头（NMJ），运动神经元和肌肉纤维之间的兴奋性胆碱能突触作为我们的模型系统，因为在这个突触的疾病对人类健康的重大影响，因为它提供了最容易的模型系统来研究体内神经递质受体再循环的过程。直到最近，受体再循环被认为是中枢神经系统中神经递质受体的独有特性，但我们发现，大量的乙酰胆碱受体（AChR）在内化后再循环回到突触后膜上，有助于维持成熟突触的突触后受体密度。我们将追求两个目标，以评估在突触发育和成熟过程中回收的潜在作用，两个目标，以测试分子的作用，这些分子是参与回收过程的强有力的候选者。我们一直专注于α-肌萎缩短蛋白和α-突触营养蛋白在调节AChR在突触后膜上的再循环中的作用，因为这些蛋白质的突变显然与人类神经肌肉传递障碍有关，并且这些基因在小鼠中的突变已被证明可以显著改变成熟突触处AChR的数量，如果受体再循环异常，则可能会出现这种情况。了解受体再循环的分子基础可能会导致更有效的干预和治疗，可以通过增加神经肌肉疾病中AChR的数量或密度来增加突触传递。此外，受体再循环的某些方面似乎对所有细胞都是共同的，因此我们期望这些结果不仅有助于理解神经肌肉接头的发育，而且将为受体再循环在突触发生和突触可塑性中的长期作用提供见解。 公共卫生相关性：神经递质受体直接在神经末梢下方的积累对于神经冲动向肌肉的健康传输是必不可少的。这项提议的目的是帮助我们更好地了解这些受体在成熟突触上聚集的方式，以及在突触连接的正常发育过程中形成的方式，并开发出在疾病削弱这些连接时加强这些连接的方法。

DESCRIPTION (provided by applicant): Our long term goal is to better understand how neurotransmitter receptor density is maintained and regulated at mature and developing synapses in vivo. We are using the neuromuscular junction (NMJ), an excitatory cholinergic synapse between motor neurons and muscle fibers as our model system, because of the significant impact on human health of disorders at this synapse and because it provides the most accessible model system to study the process of neurotransmitter receptor recycling in vivo. Until recently receptor recycling was thought to be an exclusive property of neurotransmitter receptors in the central nervous system, but we discovered that significant numbers of acetylcholine receptors (AChRs) are recycled back onto the postsynaptic membrane after internalization, contributing to the maintenance of the postsynaptic density of receptors at mature synapses. We will pursue two goals to assess potential roles for recycling during synaptic development and in maturity and two goals to test the roles of molecules that are strong candidates for participation in the recycling process. We have focused on the roles of alpha-dystrobrevin and alpha-syntrophin in regulating the recycling of AChR onto the postsynaptic membrane because mutations in these proteins are clearly associated with human disorders of neuromuscular transmission, and mutations of these genes in mice have been demonstrated to dramatically alter the number of AChR at mature synapses, as might be expected if receptor recycling was aberrant. Understanding the molecular basis of receptor recycling could lead to more effective intervention and therapy that could increase synaptic transmission by increasing AChR number or density in neuromuscular diseases. Furthermore, it seems likely that some aspects of receptor recycling will be common to all cells, so we expect that these results will be useful not only in understanding the development of the neuromuscular junction, but will provide insights into the long-term role of receptor recycling in synaptogenesis and synaptic plasticity at less accessible central synapses. PUBLIC HEALTH RELEVANCE: The accumulation of neurotransmitter receptors directly underneath nerve terminals is essential for healthy transmission of nerve impulses to muscle. The goal of this proposal is to help us better understand the ways by which these receptors are clustered at mature synapses and shaped during the normal development of synaptic connections and develop ways to strengthen these connections when they are weakened by disease.