Role of a Chloride Conductance Associated with Vesicular Glutamate Transport

 描述(申请人提供)：突触传递是一个高度调控的过程，调节大脑中的信息处理。突触传递障碍与许多神经精神疾病有关，从帕金森氏病、癫痫到自闭症谱系障碍和精神分裂症。有许多相对较好的特征因子来调节突触强度。其中许多集中在神经递质释放的概率和对单个突触小泡释放的递质的突触后反应的幅度(量子大小)。这个项目的目的是探索一个潜在的基本但知之甚少的突触前因子--每个突触小泡包装的谷氨酸的量。本项目主要研究与囊泡谷氨酸转运体(VGLUT)相关的一种新的氯电导的作用。这个项目的目标是确定这种电导在量子大小和兴奋性传递的调节中的作用。策略是确定这种电导的结构基础，并利用这一信息来测试其生理作用。利用注射了编码内化缺陷VGLUT的mRNA构建体的非洲爪哇卵母细胞，我将鉴定负责这种氯离子电导及其变构激活的序列。然后，我将从野生型VGLUT2和氯离子电导改变的突变形式的VGLUT1/2双基因敲除小鼠中拯救海马神经元。利用这一策略，我将确定氯离子电导对自发和诱发释放的影响。这些结果将为量子大小的调节提供基本的新见解，并对兴奋性神经传递具有重要意义。

 DESCRIPTION (provided by applicant): Synaptic transmission is a highly regulated process that mediates information processing in the brain. Disturbances in synaptic transmission are associated with numerous neuropsychiatric disorders from Parkinson's disease and epilepsy to autism spectrum disorders and schizophrenia. There are a number of relatively well-characterized factors that regulate synaptic strength. Many of these converge on the probability of neurotransmitter release and the amplitude of the postsynaptic response to the transmitter released by a single synaptic vesicle (quantal size). The purpose of this program is to explore a potentially fundamental but less well understood presynaptic factor-the amount of glutamate packaged per synaptic vesicle. This program focuses on the role of a novel Cl- conductance associated with the vesicular glutamate transporters (VGLUTs). The goal of this project is to determine the role of this conductance in the regulation of quantal size and excitatory transmission. The strategy is to determine the structural basis for this conductance and use this information to test its physiological role. Using Xenopus oocytes injected with mRNA constructs encoding internalization-defective VGLUTs, I will identify sequences responsible for this Cl- conductance and its allosteric activation. I will then rescue hippocampal neurons from VGLUT1/2 double knockout mice with wild type VGLUT2 and mutant forms with altered Cl- conductance. Using this strategy, I will determine the effects of the Cl- conductance on spontaneous and evoked release. The results will provide fundamental new insight into the regulation of quantal size, with important implications for excitatory neurotransmission.