Dynamic Molecular Mechanisms of Neurotransmitter Release

描述（由申请人提供）：神经递质在 突触是由突触囊泡的数量控制的， 响应钙流入而与质膜融合。的目的 建议是确定这种容易释放的囊泡的数量是如何被释放的。 调节和什么样的影响，这和其他池的囊泡可以有释放。 在整个神经系统的突触中，超微结构信息显示 不同的囊泡池。一部分囊泡停靠在血浆上 在活跃区的膜，准备融合。在胞吐作用之后， 容易释放的囊泡池必须从不同的储备中补充 聚集在活性区附近的囊泡池。慢 补充将导致突触抑制，而过度补充将 导致发射器释放增加。改变的大小和速率 因此，囊泡池的补充提供了一种强有力的调节机制， 突触的强度虽然我们相当详细地了解了 对接囊泡的融合，更少的是知道是什么控制了 这些不同的囊泡池的动力学。 急性分离的感觉毛细胞是进行这些研究的一个极好的系统 因为它们的囊泡池在解剖学上很好地表征。另外，释放 发生在细胞体的基底端，提供容易进入的部位， 递质释放和胞吐作用可以直接通过测量 囊泡融合时细胞膜电容增加。具体 目的1建立毛细胞的基本释放特性，并测试 假设递质释放在特定刺激下最有效 频率，即，发射器的释放已经调好了具体目标2测试 假设池的大小和它们之间的相互作用控制 胞吐作用它测试钙和/或蛋白激酶是否调节交通 在囊泡池之间。具体目标3检验了谷氨酸 通过突触前调节池动力学来增强其自身的释放 代谢型受体这些发现将大大推动我们的 了解突触传递。通过揭示新的机制， 调节神经递质的释放，他们可以确定目标 神经系统疾病的治疗干预。

DESCRIPTION (provided by applicant): The release of neurotransmitter at synapses is controlled by the number of synaptic vesicles that are ready for fusion with the plasma membrane in response to calcium influx. The aim of this proposal is to determine how the number of such readily-releasable vesicles is regulated and what effect this and other pools of vesicles can have on release. At synapses throughout the nervous system, ultrastructural information shows distinct pools of vesicles. A subset of vesicles is docked to the plasma membrane at the active zone, primed for fusion. Following exocytosis, this readily-releasable pool of vesicles must be replenished from a distinct reserve pool of vesicles clustered in the vicinity of the active zone. Slow replenishment will cause synaptic depression, while over-replenishment will lead to augmentation of transmitter release. Changing the size and rate of replenishment of vesicle pools thus offers a powerful mechanism for modulation of synaptic strength. While we understand in considerable detail what governs the fusion of docked vesicles, much less is known about what controls the dynamics of these distinct vesicle pools. Acutely isolated sensory hair cells are an excellent system for these studies since their vesicle pools are well characterized anatomically. Also, release occurs at the basal end of the cell body, offering easy access to the sites of transmitter release and exocytosis can be monitored directly by measuring the increase in cell membrane capacitance that occurs when vesicles fuse. Specific Aim 1 establishes the basic release properties of hair cells and tests the hypothesis that transmitter release is most efficient at a certain stimulation frequency, i.e., that transmitter release is tuned. Specific Aim 2 tests the hypothesis that the size of pools and the interaction between them control exocytosis. It tests whether calcium and/or protein kinases regulate traffic between vesicle pools. Specific Aim 3 tests the hypothesis that glutamate enhances its own release by modulating pool dynamics via presynaptic metabotropic receptors. The findings will significantly advance our understanding of synaptic transmission. By revealing novel mechanisms for the modulation of neurotransmitter release they may identify targets for therapeutic intervention in neurological diseases.