Regulation of Vesicular Glutamate Transport

描述（由申请人提供）：作为学习、记忆和成瘾等行为现象基础的突触强度的变化通常归因于受体敏感性的突触后变化，但它们也可能反映了释放的递质量的突触前调节。可用于胞吐释放的每个囊泡的谷氨酸的量取决于其通过囊泡谷氨酸转运蛋白VGLUT家族从细胞质转运到囊泡中。VGLUT 1和2，占谷氨酸的胞吐释放基本上所有完善的兴奋性神经元，表现出相互排斥的模式在成人大脑中的表达，与发射机释放的概率和可塑性的潜力。VGLUT 1还含有几个在VGLUT 2中未发现的蛋白质-蛋白质相互作用结构域。这个K 08指导临床科学家发展奖提案的长期目标是了解VGLUT亚型运输的差异如何导致在不同突触处观察到的谷氨酸盐释放的差异。该策略是研究C-末端序列在不同VGLUT亚型的活性和运输中的作用。我们已经发现，在VGLUT 1的C-末端的聚脯氨酸基序之一与参与突触囊泡回收的蛋白质相互作用。我们将描述这些相互作用，并确定它们是否通过影响囊泡填充，贩运或囊泡周期的其他方面来调节谷氨酸转运。此外，我们将表征和鉴定蛋白质与VGLUT 1中其他两个内化基序的相互作用。总之，这些基序可能有助于在谷氨酸信号转导的囊泡填充，胞吐和胞吞作用的速度的差异。越来越多的证据表明，谷氨酸功能减退在精神分裂症的病理生理学，这可能涉及谷氨酸释放的变化。因此，了解谷氨酸储存和释放的调节可能对精神分裂症治疗药物的靶向治疗很重要

DESCRIPTION (provided by applicant): The changes in synaptic strength that underlie behavioral phenomena such as learning, memory and addiction, are usually attributed to postsynaptic changes in receptor sensitivity, but they may also reflect presynaptic regulation of the amount of transmitter released. The amount of glutamate per vesicle available for exocytotic release depends on its transport from the cytoplasm into vesicles by a family of vesicular glutamate transporter proteins, VGLUTs. VGLUT1 and 2, which account for the exocytotic release of glutamate by essentially all well-established excitatory neurons, exhibit a mutually exclusive pattern of expression in adult brain that correlates with the probability of transmitter release and the potential for plasticity. VGLUT1 also contains several protein-protein interaction domains not found in VGLUT2. The long-term goal of this K08 Mentored Clinical Scientist Development Award proposal is to understand how differences in the trafficking of VGLUT isoforms contribute to the differences in glutamate release observed at different synapses. The strategy is to study the role of C-terminal sequences in activity and trafficking of the different VGLUT isoforms. We have found that one of the polyproline motifs in the C-terminus of VGLUT1 interacts with proteins involved in synaptic vesicle recycling. We will characterize these interactions and determine whether they regulate glutamate transport by influencing vesicle filling, trafficking, or other aspects of the vesicle cycle. In addition, we will characterize and identify protein interactions with two other internalization motifs in VGLUT1. Together, these motifs may contribute to differences in the speed of vesicle filling, exocytosis and endocytosis in glutamate signaling. Increasing evidence implicates glutamate hypofunction in the pathophysiology of schizophrenia, which may involve changes in glutamate release. Thus, an understanding of the regulation of glutamate storage and release may be important in the targeting of therapeutic agents for schizophrenia