Disruption of transition metal homeostasis by Cd: Implications for aging

镉对过渡金属稳态的破坏：对衰老的影响

• 批准号: 8056614
• 负责人: CAROL A FIERKE
• 金额: $ 18.8万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-06 至 2012-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8056614
• 关键词: Aging; Aging-Related Process; Biological; Biological Assay; Biological Models; Cadmium; Carcinogens; Castor; Cell Line; Cell physiology; Cells; Chemistry; Complex; Copper; Coupled; Culture Media; DNA Damage; Data; Environment; Enzymes; Eukaryota; Fibroblasts; Fluorescence; Gene Silencing; Genes; Growth; Heavy Metals; Homeostasis; House mice; Human; Image; Industrial Product; Investigation; Ions; Iron; Kidney; Life; Light; Link; Longevity; Lung; Malignant neoplasm of lung; Malignant neoplasm of prostate; Malignant neoplasm of testis; Mammalian Cell; Mammals; Maps; Mass Spectrum Analysis; Measures; Metabolism; Metalloproteins; Metals; Molecular; Molecular Chaperones; Molecular and Cellular Biology; Organism; Oxidation-Reduction; Oxidative Stress; Peromyscus; Physiological; Plasma; Play; Production; Property; Proteins; RNA Interference; Rattus norvegicus; Reactive Oxygen Species; Renal carcinoma; Resistance; Rodent; Roentgen Rays; Role; Saccharomyces cerevisiae; Saccharomycetales; Series; Side; Skin; Source; Stream; Stress; Synchrotrons; System; Testing; Testis; Toxic effect; Transition Elements; Yeasts; Zinc; bone; cadmium-binding protein; cancer risk; carcinogenesis; cigarette smoking; cofactor; demineralization; fluorescence imaging; metal metabolism; novel; public health relevance; research study; response; toxic metal; uptake

DESCRIPTION (provided by applicant): Cadmium (Cd) is a toxic heavy metal found in the environment as a product of industrial contamination, and is classified as a human carcinogen. Cd is a significant contributor to the cancer risk associated with cigarette smoke, and has been linked to lung, renal, prostate and testicular cancer. Within cells, Cd toxicity results in DNA damage, and oxidative stress, including the production of reactive oxygen species (ROS); however, cadmium is not redox active under biological conditions and cannot directly catalyze ROS production. Data recently obtained using Saccharomyces cerevisiae indicates that a significant contributor to Cd toxicity is the disruption of copper (Cu) metabolism within the cell. Cu is an essential transition metal that serves as a catalytic cofactor in numerous enzymes, but is tightly regulated within cells and is toxic at high concentrations. Both Cu and Cd have also been linked to aging in mammals. Changes in Cu metabolism accompany the aging process, and increased Cd resistance correlates with increased species lifespan. One possible explanation for this correlation is that long-lived species have developed more efficient cellular metabolism for responding to increases in Cu and other transition metals associated with Cd toxicity. This hypothesis would be consistent with the results from S. cerevisiae. However, differences in the Cd response mechanisms preclude direct extrapolation of results obtained in yeast to more complex, mammalian systems. We therefore propose a directed series of experiments to test the potential for a mechanistic linkage between Cu metabolism in mammalian cells and Cd toxicity. Specifically, we aim to: (1) Examine the impact of Cd on transition metal homeostasis in mammalian fibroblast cells, by assaying changes in total metal content and by mapping the subcellular distributions of Cu and other transition metals in normal and Cd-exposed cells using synchrotron X-ray fluorescence microprobe imaging; (2) Analyze the involvement of specific transition metal transporters and chaperones in the origins of Cd toxicity using RNAi gene silencing and metal depletion experiments; and (3) Compare the metal content and distributions in untreated and Cd-treated fibroblasts derived from the skin of short-lived, Cd-sensitive and long-lived, Cd-tolerant rodents. Together, these experiments will establish if large-scale disruption of transition metal homeostasis contributes to the molecular origins of Cd toxicity in mammals, as it does in yeast, and shed light on differences in metal homeostasis associated with increased lifespan. PUBLIC HEALTH RELEVANCE: Cadmium (Cd) is a toxic metal ion, a human carcinogen and a major contributor to the cancer risk associated with cigarette smoke. In yeast, Cd toxicity is linked to disruption of copper (Cu) metabolism; however, it is unknown if the same is true in mammals. The experiments proposed here will establish whether disrupting the homeostasis of Cu or other transition metals contributes to Cd toxicity in mammals, and examine the possibility that differences in metal metabolism contribute to the Cd tolerance of long-lived species.

描述（由申请人提供）：镉（Cd）是一种在环境中发现的有毒重金属，是工业污染的产物，被列为人类致癌物。Cd是与吸烟有关的癌症风险的一个重要因素，并且与肺癌、肾癌、前列腺癌和睾丸癌有关。在细胞内，镉毒性导致DNA损伤和氧化应激，包括产生活性氧（ROS）；然而，镉在生物条件下不具有氧化还原活性，不能直接催化ROS的产生。最近使用酿酒酵母获得的数据表明，镉毒性的一个重要因素是细胞内铜（Cu）代谢的破坏。铜是一种重要的过渡金属，在许多酶中起催化辅助因子的作用，但在细胞内受到严格调节，高浓度时有毒。铜和镉也与哺乳动物的衰老有关。铜代谢的变化伴随着衰老过程，而镉抗性的增加与物种寿命的延长有关。对这种相关性的一种可能解释是，长寿物种已经发展出更有效的细胞代谢，以应对与镉毒性相关的Cu和其他过渡金属的增加。这一假设与酿酒葡萄球菌的结果是一致的。然而，Cd反应机制的差异排除了将酵母中获得的结果直接外推到更复杂的哺乳动物系统的可能性。因此，我们提出了一系列定向实验，以测试哺乳动物细胞中铜代谢与镉毒性之间的机制联系。具体来说，我们的目标是：(1)研究Cd对哺乳动物成纤维细胞过渡金属稳态的影响，通过分析总金属含量的变化，并利用同步x射线荧光微探针成像绘制正常和Cd暴露细胞中Cu和其他过渡金属的亚细胞分布；(2)利用RNAi基因沉默和金属耗竭实验，分析特定过渡金属转运体和伴侣体在Cd毒性起源中的作用；(3)比较短寿命、cd敏感和长寿命、cd耐受啮齿动物皮肤成纤维细胞中金属的含量和分布。总之，这些实验将确定过渡金属稳态的大规模破坏是否与哺乳动物中镉毒性的分子起源有关，就像在酵母中一样，并阐明与寿命延长相关的金属稳态差异。