Glycolysis and Glutamate Storage into Synaptic Vesicles

糖酵解和谷氨酸储存到突触小泡中

• 批准号: 7455875
• 负责人: TETSUFUMI UEDA
• 金额: $ 22.68万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7455875
• 关键词: 3-phosphoglycerate; ATP Synthesis Pathway; ATP phosphohydrolase; Acute; Binding; Blood; Brain; Classical phenylketonuria; Clinical; Communication; Coupled; Dependence; Enzyme Activation; Enzymes; Generations; Glutamates; Glyceraldehyde; Glyceraldehyde 3-Phosphate; Glycolysis; Goals; Hypoglycemia; Knowledge; Learning; Mediating; Membrane; Memory; Mental Retardation; Mental disorders; Mitochondria; Molecular; Nerve Endings; Neuraxis; Neurologic; Neurons; Neurotransmitters; Numbers; Oxidoreductase; Phenylalanine; Phosphoglycerate Kinase; Play; Preparation; Process; Production; Proton Pump; Protons; Pyruvate; Pyruvate Kinase; Pyruvates; Rattus; Research; Role; Staging; Surface; Synaptic Transmission; Synaptic Vesicles; Synaptosomes; Vesicle; base; driving force; glucose metabolism; inorganic phosphate; insight; interest; kinase inhibitor; neurotransmitter uptake; novel strategies; phenylpyruvate; transmission process; uptake

DESCRIPTION (provided by applicant): Glucose metabolism is of vital importance in maintaining proper synaptic transmission and brain function. Acute glycemia induces aberrant synaptic transmission and brain function without a significant reduction in global cellular ATP levels. The mechanism is not well understood at the molecular level. We have recently provided evidence that glyceraldehyde phosphate dehydrogenase and 3-phosphoglycerate kinase, glycolytic enzymes responsible for production of ATP, are associated with synaptic vesicles and that activation of these enzymes is sufficient to support glutamate uptake into synaptic vesicles. Additional evidence suggests that glycolytically and locally produced ATP on the surface of synaptic vesicles, rather than ATP synthesized in mitochondria, plays an important role in accumulating glutamate into synaptic vesicles in the nerve ending. More recently we have obtained preliminary evidence that pyruvate kinase (PK), another glycolytic enzyme capable of ATP synthesis, is also bound to synaptic vesicles, and that activation of this enzyme leads to marked glutamate uptake into synaptic vesicles. Glutamate is a major excitatory neurotransmitter in the vertebrate central nervous system, and proper glutamate transmission is essential for neuronal communication, learning and memory function. Of interest, phenylpyruvate, whose blood levels are high in phenylketonuria, was found to inhibit PK-mediated vesicular glutamate uptake, suggesting some clinical implication for this vesicle-bound enzyme. We postulate that the synaptic vesicle-bound glycolytic enzyme PK is functionally coupled to V-type proton pump ATPase, which generates an electrochemical proton gradient (the driving force for glutamate uptake into synaptic vesicles) and thereby plays a critical role in setting the stage for glutamate transmission. We plan to provide sufficient evidence to support the hypothesis mentioned above, with the following aims: (1) to characterize vesicle-bound PK-mediated glutamate uptake into synaptic vesicles, and (2) to demonstrate that PK and phenylpyruvate play important roles in vesicular accumulation of glutamate in synaptosomes. To achieve aim 1, we will study phosphoenol pyruvate plus ADP-dependent uptake in a number of respects, using isolated rat brain synaptic vesicles. To achieve 2, we will determine the effect of membrane-permeant PK inhibitors on vesicular glutamate content in and release from synaptosomes. This study is expected to contribute to better understanding of the relation between glucose metabolism and synaptic transmission/brain function. It is hoped that knowledge gained from this research will be of use in creating a new approach to treatment of certain neurological and mental disorders.

描述（由申请人提供）：葡萄糖代谢对维持适当的突触传递和脑功能至关重要。急性脑梗死诱导异常的突触传递和脑功能，而不显著降低整体细胞ATP水平。其机制在分子水平上还没有很好的理解。我们最近提供的证据表明，甘油醛磷酸脱氢酶和3-磷酸甘油酸激酶，负责生产ATP的糖酵解酶，与突触囊泡和这些酶的激活足以支持谷氨酸摄取到突触囊泡。额外的证据表明，糖酵解和局部产生的ATP的突触囊泡表面上，而不是在线粒体中合成的ATP，在积累谷氨酸到突触囊泡在神经末梢中发挥重要作用。最近，我们已经获得了初步的证据，丙酮酸激酶（PK），另一种能够合成ATP的糖酵解酶，也结合到突触囊泡，这种酶的激活导致显着的谷氨酸摄取到突触囊泡。谷氨酸是脊椎动物中枢神经系统中主要的兴奋性神经递质，适当的谷氨酸传递对神经元的通讯、学习和记忆功能至关重要。感兴趣的是，苯丙酮酸，其血液水平高苯丙酮尿症，被发现抑制PK介导的囊泡谷氨酸摄取，这表明这种囊泡结合酶的一些临床意义。我们假设突触囊泡结合的糖酵解酶PK在功能上与V型质子泵ATP酶偶联，V型质子泵ATP酶产生电化学质子梯度（谷氨酸摄取到突触囊泡中的驱动力），从而在设定谷氨酸传输阶段中发挥关键作用。我们计划提供足够的证据来支持上述假设，目的如下：（1）表征囊泡结合的PK介导的谷氨酸摄取到突触囊泡中，以及（2）证明PK和苯丙酮酸在突触体中谷氨酸的囊泡积累中起重要作用。为了实现目标1，我们将研究磷酸烯醇丙酮酸加上ADP依赖的摄取在许多方面，使用分离的大鼠脑突触囊泡。为了实现2，我们将确定膜渗透性PK抑制剂对突触体中囊泡谷氨酸含量和释放的影响。本研究有助于更好地了解葡萄糖代谢与突触传递/脑功能之间的关系。希望从这项研究中获得的知识将有助于创造一种治疗某些神经和精神疾病的新方法。