Dynamic Molecular Mechanisms of Neurotransmitter Release

描述(申请人提供)：神经递质在 突触由准备好的突触小泡的数量控制 与质膜融合以响应钙内流。这样做的目的是 建议是确定这种容易释放的囊泡的数量是多少 以及这个囊泡池和其他囊泡池对释放有什么影响。 在整个神经系统的突触处，超微结构信息显示 明显的水泡池。囊泡的一个子集与血浆对接 活动区的膜，为融合做好准备。在胞吐之后，这是 可随时释放的囊泡池必须从不同的储备中补充 活动区附近聚集的小泡池。慢的 补充会导致突触抑制，而过度补充则会 导致发射机释放量增大。更改的大小和速率 因此，囊泡池的补充提供了一种强大的调制机制 突触的力量。虽然我们相当详细地了解什么是治理 停靠的小泡的融合，更不知道是什么控制了 这些不同的水泡池的动态。 对于这些研究来说，急性分离的感觉毛细胞是一个很好的系统 因为它们的水泡池在解剖学上有很好的特征。另外，发布 发生在细胞体的基端，提供了对 递质释放和胞吐作用可以通过测量 囊泡融合时细胞膜电容的增加。特定的 目标1建立毛细胞的基本释放特性并测试 递质释放在特定刺激下最有效的假说 频率，即发射机释放被调谐。《特定目标2》测试 池的大小和池之间的相互作用控制的假设 胞吐。它测试钙和/或蛋白激酶是否调节交通 在水泡池之间。《特定目标3》验证了谷氨酸 通过突触前调节池动态来增强自身的释放 代谢性受体。这些发现将极大地推动我们的 对突触传递的理解。通过揭示新的机制来实现 神经递质释放的调节，他们可能确定目标 神经疾病的治疗干预。

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.