Membrane Trafficking of Vesicular Neurotransmitter Transporters

多巴胺能神经传递功能障碍与许多神经精神疾病有关，包括 精神分裂症、癫痫和自闭症。虽然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，但一直被认为是 不太适合研究。突触囊泡胞吐释放谷氨酸依赖于谷氨酸包装 以及由囊泡谷氨酸转运蛋白（VGLUT）介导的再循环。VGLUT 1和2亚型表现出 成人大脑中区分皮质（VGLUT 1）和皮质下（VGLUT 2）的互补表达 连接.使用遗传编码的谷氨酸传输光学报告基因，VGLUT 1和2-pHluorins， 我们已经表征了同种型特异性分选信号和介导差异的蛋白质相互作用， VGLUT 1和2贩卖。先前与突触囊泡蛋白无关的蛋白质的参与 可能提示囊泡循环的新机制。突触前信号网络上游的亚型- 特异性VGLUT运输提供了差异调节离散脑中谷氨酸释放的机会 通路，并确定新的治疗靶点，使神经精神疾病的脑回路正常化。这些 机制也可能不同地依赖于神经元放电率，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。拟议的长期目标 研究的目的是了解单个囊泡蛋白的膜运输如何影响蛋白质 突触囊泡的组成，突触囊泡池的维持，以及通过突触囊泡释放递质。 具体电路。该建议的策略是研究异构体特异性的上游信号通路， VGLUT突触囊泡再循环。这项建议的具体目的是研究对 囊泡谷氨酸转运蛋白的运输：1）表征VGLUT 1再循环的调节， 泛素连接酶相互作用，2）表征肌醇六磷酸对VGLUT 2再循环的调节 激酶，和3）表征异构体特异性运输如何在突触发育中变化。作为关键 突触传递的介质，这些囊泡蛋白和调节其表达的因子， 定位和活动可以显著影响神经递质的释放， 治疗目标调节神经递质的释放可能是治疗抑郁症的重要途径。 干预分子机制为开发更好的治疗方法提供了新的目标， 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.