The role of vesicle recycling in synaptic depression

囊泡回收在突触抑制中的作用

• 批准号: 7023868
• 负责人: Ege T Kavalali
• 金额: $ 27.42万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-12 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7023868
• 关键词: action potentials; calcium flux; diacylglycerols; electron microscopy; hippocampus; laboratory mouse; laboratory rat; neural plasticity; neural transmission; neuroregulation; neurotransmitter transport; protein structure function; second messengers; synaptic vesicles; synaptotagmin; tissue /cell culture; transfection

DESCRIPTION (provided by applicant): In response to high frequency action potential firing synapses exhibit extensive depression. This common form of synaptic plasticity brings computational advantage to synaptic circuits by increasing the sensitivity of neurons to subtle temporal changes in synaptic inputs. This depression is thought to be a direct outcome of the dynamics of vesicle recycling and vesicle depletion in presynaptic terminals. However, a clear mechanistic link between the dynamics of synaptic vesicle cycle and phases of synaptic depression is still lacking. The main goal of this project is to bridge this gap using a powerful combination of electrophysiology, optical imaging, electron microscopy and molecular biology in hippocampal synapses. Our studies have recently shown that synaptotagmin7 forms a molecular switch controlling the rate of vesicle recycling in a bi-directional manner through its alternative splice variants. This observation sets the stage for studies aimed at understanding the exact relationship between synaptic vesicle recycling and synaptic output. To fulfill this goal three specific aims are proposed. In the first specific aim, the regulation of vesicle recycling and synaptic depression by activity and second messengers, such as calcium and diacylglycerol, will be studied using fluorescent measurement of vesicle recycling and electrophysiology. In the second specific aim, the fast and slow recycling will be molecularly dissected through overexpression of synaptotagmin7 splice variants to examine their respective roles in regulation of presynaptic dynamics and neurotransmitter release. These functional experiments will be complemented by morphological analysis of synapse structure using electron microscopy. In the third specific aim, structural elements within synaptotagmin7 that control synaptic vesicle recycling will be identified through structure-function analysis in transfected synapses. These concerted investigations will enable us to understand with increasing precision the mechanistic link between recycling of synaptic vesicles and short-term synaptic plasticity. This information will also be critical for a better understanding of the pathologies underlying several neurological and psychiatric illnesses ranging from epilepsy to schizophrenia.

描述（由申请人提供）：响应高频动作电势射击突触表现出广泛的抑郁症。这种常见的突触可塑性形式通过增加神经元对突触输入的微妙时间变化的敏感性来带来突触电路。这种抑郁被认为是突触前末端中囊泡回收和囊泡耗竭动力学的直接结果。然而，仍然缺乏突触囊泡周期和突触抑郁阶段的动力学之间的明确机械联系。该项目的主要目的是使用电生理学，光学成像，电子显微镜和海马突触中的分子生物学的强大组合弥合这一差距。我们的研究最近表明，突触触摸符7通过其替代剪接变体以双向方式形成分子开关，以双向方式控制囊泡回收的速率。该观察结果为研究阶段奠定了旨在理解突触囊泡回收与突触输出之间的确切关系的阶段。为了实现这一目标，提出了三个具体目标。在第一个特定目的中，将通过荧光测量囊泡回收和电生理学来研究囊泡回收和突触抑制的囊泡回收和突触抑制。在第二个特定目标中，快速和缓慢的回收利用将通过过度表达突触的剪接变体来分子解剖，以检查它们在调节突触前动力学和神经递质释放中的各自作用。这些功能实验将通过电子显微镜对突触结构的形态分析进行补充。在第三个特定目的中，将通过转染的突触中的结构 - 功能分析来识别突触囊泡回收的突触构成囊泡回收的结构元素。这些协同的研究将使我们能够以越来越高的精度理解突触囊泡的回收与短期突触可塑性之间的机械联系。这些信息对于更好地理解从癫痫到精神分裂症的几种神经系统和精神病疾病的病理学也至关重要。