Membrane Trafficking of Vesicular Monoamine Transporter

突触传递依赖于神经递质的有效包装 变成专门的分泌囊泡对于合成的单胺， 在细胞质中，该包装需要穿过囊泡膜的主动运输。 干扰囊泡胺转运的药物具有深刻的精神 影响，表明这种活动在精神疾病中的重要性。 有趣的是，单胺储存在两个不同的分泌囊泡中： 突触囊泡（SV）和大致密核心囊泡（LDCV）。SV快速介导 突触传递，而LDCV具有神经调节作用。而 特定的运输活性定义了分泌囊泡的内容物， 转运蛋白在不同囊泡上的定位将决定 单胺释放的方式和部位。这项建议的长远目标是 了解神经递质储存和释放的变化如何影响 突触传递，以及行为。策略是研究排序 将单胺包装成不同分泌形式的转运蛋白 囊泡使用PC 12细胞作为模型系统，我们已经发现， 单胺转运蛋白（VMAT）优先定位于LDCV，而 密切相关的囊泡乙酰胆碱转运蛋白（VAChT），优先于 SV。我们将重点关注神经元VMAT 2在本研究中的作用机制 参与VMAT 2到LDCV的分类，具有以下特定目的：1） 研究VMAT2分类为分泌囊泡的途径。2)到 鉴定将VMAT 2靶向LDCV的分选序列。3)以识别 调节VMAT2分选的相互作用蛋白。拟议的研究将 确定参与的途径，排序序列和调节蛋白， VMAT2在神经内分泌细胞和神经元中的分泌囊泡的分选。 这一信息将有助于我们了解单胺能神经元 神经传递在储存和释放水平上受到调节。这项工作 也将允许我们在未来从基因上改变VMAT 2的定位， 并确定单胺释放的生物学意义 LDCV和SV，这可能会导致更好地理解功能 由胺能途径调节，例如那些潜在的药物寻求和 精神病行为。

Synaptic transmission depends on the efficient packaging of neurotransmitters into specialized secretory vesicles. For monoamines that are synthesized in the cytoplasm, this package requires active transport across the vesicle membrane. Drugs that interfere with vesicular amine transport have profound psychotropic effects, indicating the importance of this activity in psychiatric diseases. Interestingly, monoamines are stored in two distinct secretory vesicles: synaptic vesicles (SVs) and large dense core vesicles (LDCVs). SVs mediate fast synaptic transmission, while LDCVs have a neuromodulatory role. Whereas the specific transport activity defines the content of secretory vesicles, the localization of the transport protein on distinct vesicles will determine the mode and site of monoamine release. The long-term objective of this proposal is to understand how changes in neurotransmitter storage and release influence synaptic transmission, and hence behavior. The strategy is to study the sorting of the transport proteins that package monoamines into distinct secretory vesicles. Using PC 12 cells as a model system, we have found that vesicular monoamine transporters (VMATs) preferentially localize to LDCVs whereas the close related vesicular acetylcholine transporter (VAChT), preferentially to SVs. We will focus on neuronal VMAT2 in this proposal to explore the mechanisms involved in the sorting of VMAT2 to LDCVs with the following Specific Aims: 1) To examine the routes by which VMAT2 sorts to secretory vesicles. 2) To identify the sorting sequences that target VMAT2 to LDCVs. 3) To identify interacting proteins that regulate VMAT2 sorting. The proposed studies will identify the routes, sorting sequences, and the regulatory proteins involved in the sorting of VMAT2 to secretory vesicles in neuroendocrine cells and neurons. This information will facilitate our understanding of how the monoaminergic neural transmission is regulated at the level of storage and release. This work will also allow us in the future to genetically alter the localization of VMAT2 in vivo and determine the biological significance of monoamine release from LDCVs as well as SVs, which could lead to better understanding of the functions regulated by aminergic pathways, such as those underlying drug seeking and psychotic behaviors.