MECHANISTIC INSIGHTS INTO CADMIUM DETOXIFICATION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 非生理性金属的解毒和营养但有毒金属的稳态获取是基本的生物过程。镉是一种剧毒的环境污染物，会导致许多人类疾病，包括肾脏疾病、癌症和内分泌紊乱。细胞氧化损伤、营养金属动态平衡的紊乱、DNA修复的抑制和雌激素活性与镉的毒性有关。然而，真核生物中镉的解毒机制，特别是镉的排泄系统，在很大程度上还不清楚。该项目的长期目标是描述镉解毒的分子机制，并利用这一知识减少镉对人类的暴露。在寻找酿酒酵母抗重金属相关基因的过程中，我们发现了一个P型ATPase。从细菌到人类的所有生物体都依赖于这种转运蛋白家族来维持各种离子的跨膜梯度。我们的数据有力地表明，这个P型ATPase是一个镉选择性输出子。此外，当细胞生长在含镉的培养液中时，这种转运蛋白的表达水平通过镉介导的抑制活性周转而迅速上调。这一应用重点是对该镉转运蛋白的功能、作用机制和调控进行表征。中心假设是这种P型ATPase是第一个镉特异的外排泵，在结构、底物特异性和调节方式上都是独一无二的。这一假设将通过生化、细胞生物学和遗传学方法进行检验。首先，将阐明P型ATPase的金属特异性。这项研究将主要集中在体内金属抗性和蓄积性测定以及体外ATPase测定上。其次，结合酵母遗传学、细胞生物学和化学的多学科方法将识别参与这种P型ATPase的镉依赖翻译后控制的独特模式的调控元件。这些研究将揭示酵母中一种新的由P型ATPase介导的镉解毒机制，并最终提高我们对抗人类镉相关疾病的能力。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Detoxification of non-physiological metals and homeostatic acquisition of nutritional yet toxic metals are fundamental biological processes. Cadmium is a highly toxic environmental contaminant, which causes a number of human disorders, including kidney disease, cancer, and endocrine disruption. Oxidative cellular damage, perturbation of nutritional metal homeostasis, inhibition of DNA repair, and estrogenic activities are implicated with cadmium toxicity. However, the mechanisms of cadmium detoxification in eukaryotes, especially cadmium excretion systems, are largely unknown. The long-term goals of this project are the characterization of molecular mechanisms of cadmium detoxification and employing this knowledge to reduce cadmium exposure to humans. During the search for genes involved in heavy metal resistance in yeast Saccharomyces cerevisiae, we have identified a P-type ATPase. All organisms ranging from bacteria to humans rely on this family of transporters for maintaining a trans-membrane gradient of various ions. Our data strongly suggest that this P-type ATPase is a cadmium selective exporter. Moreover, when cells grow in cadmium-containing media, the expression levels of this transporter are rapidly up regulated through cadmium-mediated inhibition of active turnover. This application focuses on characterization of the function, mechanisms of action and regulation of this cadmium transporter. The central hypothesis is that this P-type ATPase is the first cadmium-specific efflux pump that is unique in structure, substrate specificity and mode of regulation. This hypothesis will be tested using biochemical, cell biological and genetic approaches. First, metal specificity of the P-type ATPase will be elucidated. This study will largely focus on in vivo metal resistant and accumulation assays and in vitro ATPase assays. Second, a multi-disciplinary approach combining yeast genetics, cell biology and chemistry will identify regulatory elements involved in the unique mode of cadmium-dependent post-translational control of this P-type ATPase. The proposed studies will reveal a novel cadmium detoxification mechanism mediated by a P-type ATPase in yeast, a model eukaryote, and ultimately advance our ability to combat cadmium related disorders in humans.