Cellular Mechanisms of Neuronal Metal Transport and Toxicity

神经元金属转运和毒性的细胞机制

• 批准号: 7086650
• 负责人: Victor Faundez
• 金额: $ 28.71万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7086650
• 关键词: cytotoxicity; intracellular transport; laboratory mouse; laboratory rat; metal metabolism; neuronal transport; protein localization; protein protein interaction; proteomics; synaptic vesicles; transport proteins; ubiquitin; vesicle /vacuole; zinc

DESCRIPTION (provided by applicant): Zinc plays fundamental and diverse roles in cells yet excess free zinc is associated with metal cytotoxicity. To balance these opposing effects, cells have evolved universal mechanisms controlling cytoplasmic metal concentration. Cells accomplish this goal by zinc extrusion into the extracellular space, chelation by cytosolic chaperones, or sequestration within intracellular compartments. This last mechanism is the less explored process and it constitutes the main focus of our proposal. Zinc plays fundamental roles in synaptic physiology as well as in acute and chronic pathological conditions, ranging from excitotoxicity to the formation of amyloid aggregates characteristic of neurodegenerative diseases. Despite these fundamental roles of zinc, our understanding of the contribution of intracellular compartment in metal sequestration and homoeostasis is limited. In neurons, organellar zinc is stored in synaptic vesicles (SVs) by the activity of a synaptic vesicle specific zinc transporter, ZnT3. We have isolated and characterized by proteomics a ZnT3- enriched vesicle population. In these vesicles, we have identified ~ 140 molecular targets, several of which either up- or down-regulate vesicular endosomal zinc stores. These molecules provide a unique set of tools to assess the role of intracellular organelles, en particular endosomes and SV, in normal and pathological metal homeostasis. Our studies suggest that ZnT3 transport function are regulated by the nature of the compartment in which the ZnT3 transporter resides. Consistent with this notion, we have identified three targeting mechanisms that control ZnT3 subcellular localization that have the potential to regulate ZnT3 zinc transport function. In this proposal, we will specifically explore these novel regulatory paradigms testing the hypothesis that endosome-specific zinc transporter interactions regulate zinc transporter activity and resistance to metal-induced cytotoxicity.

描述（由申请人提供）：锌在细胞中发挥着基本且多样化的作用，但过量的游离锌与金属细胞毒性有关。为了平衡这些相反的作用，细胞进化出了控制细胞质金属浓度的通用机制。细胞通过将锌挤出到细胞外空间、通过胞质伴侣螯合或隔离在细胞内隔室中来实现这一目标。最后一个机制是较少探索的过程，它构成了我们提案的主要焦点。锌在突触生理学以及急性和慢性病理状况中发挥着重要作用，从兴奋性毒性到神经退行性疾病特征的淀粉样蛋白聚集体的形成。尽管锌具有这些基本作用，但我们对细胞内区室在金属螯合和体内平衡中的贡献的理解仍然有限。在神经元中，细胞器锌通过突触小泡特异性锌转运蛋白 ZnT3 的活性储存在突触小泡 (SV) 中。我们通过蛋白质组学分离并表征了富含 ZnT3 的囊泡群体。在这些囊泡中，我们已经鉴定出约 140 个分子靶标，其中几个可以上调或下调囊泡内体锌的储存。这些分子提供了一套独特的工具来评估细胞内细胞器（特别是内体和 SV）在正常和病理性金属稳态中的作用。我们的研究表明，ZnT3 转运功能受 ZnT3 转运蛋白所在区室的性质调节。与这一概念一致，我们已经确定了三种控制 ZnT3 亚细胞定位的靶向机制，这些机制有可能调节 ZnT3 锌转运功能。在本提案中，我们将专门探索这些新颖的监管范式，测试内体特异性锌转运蛋白相互作用调节锌转运蛋白活性和对金属诱导的细胞毒性的抵抗力的假设。