Membrane Trafficking of Vesicular Neurotransmitter Transporters

谷氨酸能神经传递功能障碍与许多神经精神障碍有关，包括 精神分裂症、癫痫和自闭症。尽管突触后受体受到了最多的关注， 控制谷氨酸释放的突触前机制也是有希望的治疗靶点，但 不那么容易学习。突触囊泡胞吐释放谷氨酸依赖于谷氨酸包装 和囊泡谷氨酸转运体(VGLUT)介导的循环。VGLUT1和2亚型 成人大脑区分皮质(VGLUT1)和皮质下(VGLUT2)的互补表达 关系。使用遗传编码的谷氨酸传递光学记者VGLUT1和2-PHluorins， 我们已经确定了调节差异的异构体特定的分选信号和蛋白质相互作用的特征 VGLUT1和2贩运。先前与突触小泡蛋白无关的蛋白质的参与 可能会为囊泡回收提供新的机制。突触前信号网络上游的异构体- 特异的VGLUT转运为差异调节离散脑中谷氨酸的释放提供了机会 途径，并确定新的治疗靶点，使神经精神疾病的大脑回路正常化。这些 机制也可能不同地取决于神经元的放电率，从而提供了抑制过度放电的可能性。 活动，同时允许正常的生理传输进行。建议的长期目标是 研究是为了了解单个泡囊蛋白的膜运输如何影响蛋白质 突触小泡的组成、突触小泡池的维持和递质的释放 特定的电路。这项建议的策略是研究异构体特异性上游的信号通路 VGLUT突触小泡回收。这项提案的具体目的是为了研究对 囊泡谷氨酸转运体的运输1)表征VGLUT1循环的调控 泛素连接酶相互作用，2)六烷基磷酸肌醇对VGLUT2循环的调控 以及3)表征了同工型运输如何在突触发育过程中发生变化。作为关键字 突触传递的媒介，这些囊泡蛋白和调节它们表达的因素， 定位和活动可以极大地影响神经递质的释放，使它们变得有希望。 治疗靶点。调节神经递质的释放可能是治疗的重要途径 干预。分子机制为开发更好的治疗方法提供了新的靶点。 神经精神障碍。

Dysfunction of glutamatergic neurotransmission is implicated in many neuropsychiatric disorders, including schizophrenia, epilepsy and autism. Although postsynaptic receptors have received the most attention, presynaptic mechanisms controlling glutamate release are also promising therapeutic targets, but have been less amenable to study. Glutamate release by synaptic vesicle exocytosis depends on glutamate packaging and recycling mediated by vesicular glutamate transporters (VGLUTs). VGLUT1 and 2 isoforms exhibit complementary expression in adult brain that distinguishes cortical (VGLUT1) and subcortical (VGLUT2) connections. Using genetically encoded optical reporters of glutamate transmission, VGLUT1 and 2-pHluorins, we have characterized the isoform-specific sorting signals and protein interactions that mediate differences in VGLUT1 and 2 trafficking. The involvement of proteins previously not associated with synaptic vesicle proteins may suggest novel mechanisms for vesicle recycling. Presynaptic signaling networks upstream of isoform- specific VGLUT trafficking present an opportunity to differentially modulate glutamate release in discrete brain pathways, and identify novel therapeutic targets to normalize brain circuits in neuropsychiatric disease. These mechanisms may also differentially depend on neuronal firing rate, offering the possibility of dampening excess activity while allowing normal physiological transmission to proceed. The long-term goal of the proposed research is to understand how membrane trafficking of individual vesicular proteins influences the protein composition of synaptic vesicles, the maintenance of synaptic vesicle pools, and the release of transmitter by specific circuits. The strategy of this proposal is to study signaling pathways upstream from isoform-specific VGLUT synaptic vesicle recycling. The specific aims of this proposal are designed to study the regulation of trafficking of vesicular glutamate transporters by 1) characterizing the modulation of VGLUT1 recycling by ubiquitin ligase interactions, 2) characterizing modulation of VGLUT2 recycling by inositol hexakisphosphate kinases, and 3) characterizing how isoform-specific trafficking changes over synapse development. As key mediators of synaptic transmission, these vesicular proteins and the factors that modulate their expression, localization and activity can dramatically influence neurotransmitter release, making them promising therapeutic targets. Regulation of neurotransmitter release may be an important approach to therapeutic intervention. The molecular machinery offers new targets for the development of better treatments for neuropsychiatric disorders.