Regulation of PIP2 Metabolism in Nerve Terminals

神经末梢 PIP2 代谢的调节

• 批准号: 7682085
• 负责人: Belle Chang
• 金额: $ 4.1万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7682085
• 关键词: Affect; Biochemical; Biological Assay; Brain; Calcium; Caliber; Cell Line; Cell membrane; Cells; Clathrin; Cytosol; Data; Defect; Endocytosis; Ensure; Enzymes; Fluorescent Dyes; Hippocampus (Brain); Hydrolysis; Impairment; Intracellular Membranes; Lead; Lipids; Liposomes; Measurement; Measures; Mediating; Membrane; Metabolism; Molecular; Mus; Nerve; Neurons; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositol Phosphates; Phosphatidylinositols; Phospholipids; Phosphoric Monoester Hydrolases; Phosphotransferases; Presynaptic Terminals; Process; Protein Dephosphorylation; Proteins; Radiolabeled; Recycling; Regulation; Retrieval; Role; Running; Signal Transduction; Site; Staging; Synapses; Synaptic Vesicles; Technology; Testing; Thin Layer Chromatography; Vesicle; insight; lipid metabolism; nervous system disorder; neurotransmitter release; radiotracer; sensor; synaptic function; synaptojanin; trafficking; uptake

DESCRIPTION (provided by applicant): The synaptic vesicle cycle ensures the steady release of neurotransmitters at the nerve terminals from the presynaptic membrane through a sequence of steps from calcium-triggered vesicle fusion at active zones and release of neurotransmitters to the recycling and re-loading of the synaptic vesicles. The recycling of the synaptic vesicles is essential in order to replenish the neuron with new fusion-competent vesicles for subsequent rounds of neurotransmitter release. Various modes of retrieval of synaptic vesicles from the plasma membrane after synapse stimulation have been described, including clathrin-mediated endocytosis. Understanding the molecular mechanisms regulating synaptic vesicle trafficking will provide insight into synaptic function and why-certain neurological diseases arise when these mechanisms are not properly in place. Proteins involved in the synaptic vesicle cycle have been well described and recent identification of proteins involved in lipid metabolism has revealed a role for lipids and their metabolism in the synaptic vesicle cycle. In particular, studies have implicated a fundamental role of phosphatidylinositol-4,5-bisphosphate (PIP2)and other phosphoinositides in this process. Disruption of two main enzymes regulating the levels of PIP2 at the synapse, phosphatidylinositol phosphate kinase type 1 gamma and the phosphoinositide phosphatase synaptojanin 1 (Synjl), was shown to produce defects at multiple stages in the synaptic vesicle cycle, thereby reflecting the multifaceted role of PIP2 in signaling at the synapse. The phospholipid PIP2 is found to be enriched on the plasma membrane and at significantly lower levels in intracellular membranes. This proposal strives to study the mechanisms controlling the spatial restriction of PIP2 dephosphorylation at the plasma membrane that mediate endocytosis of synaptic vesicles. The hypothesis is that the PIP2 hydrolysis machinery utilizes membrane curvature generators/sensors, such as BAR proteins, to eliminate this lipid preferentially from curved membranes rather than flat ones. This idea suggests that PIP2 hydrolysis occurs on endocytic buds rather than the relatively flat plasma membrane. The tight interaction between a membrane curvature generator/sensor, endophilin, and Synj1 has been demonstrated. Our lab has preliminary biochemical data that suggests that PIP2 hydrolysis is affected by membrane curvature. Elucidation of the involvement of the PIP2 in the synaptic vesicle cycle and the mechanisms that control the levels of PIP2 will aid in the further understanding of synaptic function. Defects in the mechanisms that regulate PIP2 lead to impairment of synaptic function and can give rise to neurological disorders.

描述（由申请人提供）：突触囊泡周期确保神经递质在神经终端从突触前膜上稳定释放，通过一系列步骤，从钙触发的囊泡融合在活性区域和神经递质的释放中释放到恢复和重新加载consimim fistic fifie的囊泡融合。突触囊泡的回收对于为了用新的融合功能的囊泡补充神经元，以进行随后的神经递质释放。已经描述了突触刺激后从质膜中检索突触囊泡的各种模式，包括网格蛋白介导的内吞作用。了解调节突触囊泡运输的分子机制将提供有关突触功能的洞察力，以及当这些机制不正确时出现神经系统疾病的原因。参与突触囊泡周期的蛋白质已经得到很好的描述，最近鉴定出参与脂质代谢的蛋白质已经揭示了脂质及其代谢在突触囊泡循环中的作用。特别是，研究暗示了磷脂酰肌醇-4,5-双磷酸（PIP2）和其他磷酸肌醇在此过程中的基本作用。 Disruption of two main enzymes regulating the levels of PIP2 at the synapse, phosphatidylinositol phosphate kinase type 1 gamma and the phosphoinositide phosphatase synaptojanin 1 (Synjl), was shown to produce defects at multiple stages in the synaptic vesicle cycle, thereby reflecting the multifaceted role of PIP2 in signaling at the synapse.发现磷脂PIP2在质膜上富集，在细胞内膜中的水平明显较低。该提案旨在研究控制质膜上pIP2去磷酸化空间限制的机制，以介导突触囊泡的内吞作用。假设是，PIP2水解机械利用膜曲率发电机/传感器（例如BAR蛋白）从弯曲的膜而不是扁平的膜上优先消除这种脂质。这个想法表明，PIP2水解发生在内吞芽上，而不是相对平坦的质膜。已经证明了膜曲率发生器/传感器，内菲尔蛋白和Synj1之间的紧密相互作用。我们的实验室具有初步的生化数据，表明PIP2水解受膜曲率的影响。阐明PIP2参与突触囊泡循环和控制PIP2水平的机制将有助于进一步理解突触功能。调节PIP2的机制缺陷会导致突触功能受损，并可能导致神经系统疾病。