Divalent Metal Transporter: Role in Manganese Toxicity

二价金属转运蛋白：在锰毒性中的作用

• 批准号: 6470013
• 负责人: JEROME Allan ROTH
• 金额: $ 26.86万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-26 至 2005-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6470013
• 关键词: PC12 cells; antisense nucleic acid; apoptosis; brain cell; brain metabolism; divalent metal; enzyme linked immunosorbent assay; gene expression; gene mutation; glycosylation; heavy metals; immunocytochemistry; immunofluorescence technique; intracellular transport; iron metabolism; laboratory rat; manganese; membrane transport proteins; messenger RNA; metal poisoning; neurons; neurotoxicology; nucleoproteins; phosphorylation; protein isoforms; protein localization; protein structure function

DESCRIPTION (provided by applicant): Chronic exposure to the divalent heavy metals, lead, manganese (Mn) and chromium, has all been linked to development of severe and irreversible neurological disorders as well as increased risk to develop Parkinson disease. Although the mechanisms by which these metals induce neuronal cell death are not well defined, neurotoxicity is regulated by a number of factors, one of which is the transport of these metals across the blood brain barrier and their subsequent uptake within targeted neuron. Once inside the neuron these heavy metals provoke a series of biochemical and molecular events leading to cell death induced by apoptosis and/or necrosis. In the case of Mn, chronic high level exposure provokes a syndrome resembling Parkinson?s disease, which at the latter stages consists of severe extrapyramidal dysfunction. Recent studies have indicated that Mn toxicity is integrally linked to transport and disposition of iron. Mn is predominantly taken up into cells via the same transporter responsible for iron uptake, i.e. the divalent metal transporter, DMT1. This transporter has a very broad specificity and is responsible for the cellular uptake of other divalent cations as well, including Cd+2, Zn+2, Co+2, Ni+2, Cu+2 and Pb+2. One of the two forms of DMT1, the form containing the iron-response element (+IRE) in the 3?-noncoding region of the message, is negatively regulated by iron status such that if iron levels are low, DMT1 expression is elevated resulting in increased transport and the potential for enhanced metal toxicity. The other form (-IRE) presumably is not regulated in this fashion. Recent studies have demonstrated that the two isoforms of DMT1 (+/-IRE) are distributed in different subcellular compartments with the -IRE species selectively present in the nucleus of neuronal and neuronal-like cells. However, the function and structure of this nuclear-based form of DMT1 have not been determined. Accordingly, we propose to examine the function of both the +IRE and -IRE forms of DMT1 and their contribution to the cellular uptake and subcellular distribution of Mn and their role in supporting heavy metal neurotoxicity. We have a unique ability to study the function of DMT1 in regulating Mn and other heavy metal toxicity since Dr. Michael Garrick, a coinvestigator in this grant, has an animal model, the Belgrade rat, with a mutation in DMT1 making it functionally inactive. Accordingly, the following studies are proposed: 1) determine the contribution of the +/-IRE forms of DMT1 in supporting iron and Mn transport and toxicity, 2) characterize factors regulating expression of +/-IRE forms of DMT1, 3) determine the structural features promoting nuclear localization of the -IRE form of DMT1, 4) determine the function of nuclear DMT1 and its contribution to Mn-induced toxicity, and 5) localization of the +/-IRE isoforms in rat brain.

描述（由申请人提供）： 长期接触二价重金属 铅、锰 (Mn) 和铬等金属都与发展有关 严重且不可逆的神经系统疾病以及增加的风险 发展帕金森病。尽管这些金属诱导的机制 神经元细胞死亡尚无明确定义，神经毒性受 许多因素，其中之一是这些金属在整个过程中的运输 血脑屏障及其随后在目标神经元内的摄取。一次 在神经元内部，这些重金属会引发一系列生化和 导致细胞凋亡和/或坏死诱导的细胞死亡的分子事件。在 就锰而言，长期高水平接触会引发类似的综合症 帕金森病，在后期阶段包括严重的 锥体外系功能障碍。最近的研究表明，锰的毒性是 与铁的运输和处置密切相关。 Mn主要是 通过负责铁吸收的同一转运蛋白被吸收到细胞中，即 二价金属转运蛋白 DMT1。该运输机具有非常广泛的 特异性并负责其他二价的细胞摄取 阳离子，包括 Cd+2、Zn+2、Co+2、Ni+2、Cu+2 和 Pb+2。中的一个 DMT1 的两种形式，其中含有铁反应元件 (+IRE) 的形式 3?-消息的非编码区域，受到铁状态的负调节，例如 如果铁水平较低，DMT1 表达就会升高，从而导致铁含量增加 运输和增强金属毒性的可能性。另一种形式（-IRE） 想必不受这种方式的监管。最近的研究表明 DMT1 (+/-IRE) 的两种亚型分布在不同的亚细胞中 具有-IRE物种选择性存在于细胞核中的区室 神经元和神经元样细胞。然而，这个功能和结构 DMT1 的核形式尚未确定。据此，我们建议 检查 DMT1 的 +IRE 和 -IRE 形式的功能及其 对 Mn 和 Mn 的细胞摄取和亚细胞分布的贡献 它们在支持重金属神经毒性方面的作用。我们拥有独特的能力 研究DMT1调节Mn和其他重金属毒性的功能 因为这项资助的共同研究员迈克尔·加里克博士有一个动物模型， 贝尔格莱德大鼠，DMT1 发生突变，使其功能失活。 因此，建议进行以下研究：1）确定贡献 DMT1 的 +/-IRE 形式支持铁和锰的转运和毒性， 2) 表征调节 DMT1 +/-IRE 形式表达的因素，3) 确定促进-IRE核定位的结构特征 DMT1 的形式，4) 确定核 DMT1 的功能及其对 Mn 诱导的毒性，以及 5) +/-IRE 同工型在大鼠脑中的定位。