Hypoxia and Epigenetic Mechanisms for Toxicity

缺氧和毒性的表观遗传机制

• 批准号: 7097467
• 负责人: JOHN J LAPRES
• 金额: $ 27.28万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-19 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7097467
• 关键词: RNA interference; biological signal transduction; cell line; cytotoxicity; environmental exposure; environmental toxicology; enzyme inhibitors; flow cytometry; gene deletion mutation; gene environment interaction; gene expression; genetic transcription; genetically modified animals; histopathology; hydroxylation; hypoxia; hypoxia inducible factor 1; laboratory mouse; lung disorder; membrane transport proteins; metal poisoning; oxygenases; recombinase; transcription factor; transfection

DESCRIPTION (provided by applicant): Exposure to ferrous-like metals lead to multiple toxic endpoints, including lung and erythropoietic abnormalities, and cancer. Many different mechanisms have been proposed to explain the toxicity of ferrous-like metals. Our preliminary data and recent publications suggest that the hypoxia signaling system may play a role in metal induced injury. The ability to sense and cope with low oxygen tension, or hypoxia, is critical to normal physiology and several pathological conditions. Organisms have developed a mechanism of coping with hypoxia and central to this process are the hypoxia inducible factors (HIFs). HIFs are inducible transcription factors that regulate the expression of a battery of genes essential to dealing with a hypoxic environment. These hypoxia responsive genes are also affected by ferrous-like metals, such as cobalt and nickel. Recently, a family of prolyl hydroxylases was identified that act as oxygen sensors for the HIF proteins. These enzymes can be inhibited by ferrous-like metals and offer a link between hypoxia and metal exposure. This intersection has led us to the following hypothesis: HIF mediated transcription is necessary for cellular damage and lung toxicity caused by exposure to ferrous-like metals. To address this hypothesis five specific aims are proposed: 1) Create and characterize ARNT deficient cells. 2) Characterize the role of HIF signaling in metal induced toxicity with HIF deficient cell lines. 3) Determine whether metal induced toxicity is dependent upon stabilization of the HIFs through inhibition of prolyl. hydroxylation. 4) Determine the role of HIF regulated genes in mediating metal induced toxicity using RNAi. 5) Determine whether HIF mediated signaling is necessary for metal induced lung toxicity using HIF1 n and ARNT conditional null mice. The completion of the proposed research will increase our understanding of the signaling mechanism used by ferrous-like metals. The studies will link ferrous-like metals to the hypoxia response pathway and its down-stream target genes. The proposal will create a set of cell lines that will have broad interest in several fields, including oncology, toxicology, and pharmacology. In addition, the understanding we gain about hypoxia and HIF mediated signaling will have benefits to developmental and cancer biology. Finally, these studies will elucidate the role of hypoxia signaling in metal induced toxicity in vitro and in vivo.

描述（由申请人提供）：接触类铁金属会导致多种毒性终点，包括肺和红细胞生成异常以及癌症。 人们提出了许多不同的机制来解释类铁金属的毒性。 我们的初步数据和最近的出版物表明缺氧信号系统可能在金属诱导的损伤中发挥作用。感知和应对低氧张力或缺氧的能力对于正常生理和多种病理状况至关重要。生物体已经形成了应对缺氧的机制，而这一过程的核心是缺氧诱导因子（HIF）。 HIF 是诱导性转录因子，可调节应对缺氧环境所必需的一系列基因的表达。这些缺氧反应基因也受到钴和镍等铁类金属的影响。最近，一个脯氨酰羟化酶家族被鉴定为 HIF 蛋白的氧传感器。这些酶可以被亚铁类金属抑制，并提供缺氧和金属暴露之间的联系。 这种交叉使我们得出以下假设：HIF 介导的转录对于接触亚铁类金属引起的细胞损伤和肺毒性是必要的。 为了解决这一假设，提出了五个具体目标：1）创建并表征 ARNT 缺陷细胞。 2) 表征 HIF 信号在金属诱导的 HIF 缺陷细胞系毒性中的作用。 3) 确定金属诱导的毒性是否依赖于通过抑制脯氨酰来稳定 HIF。羟基化。 4) 使用 RNAi 确定 HIF 调节基因在介导金属诱导毒性中的作用。 5) 使用 HIF1 n 和 ARNT 条件无效小鼠确定 HIF 介导的信号传导对于金属诱导的肺毒性是否是必需的。 拟议研究的完成将增加我们对类黑色金属所使用的信号机制的理解。 这些研究将把类亚铁金属与缺氧反应途径及其下游靶基因联系起来。 该提案将创建一组细胞系，这些细胞系将在肿瘤学、毒理学和药理学等多个领域引起广泛关注。 此外，我们对缺氧和 HIF 介导的信号传导的了解将有利于发育和癌症生物学。 最后，这些研究将阐明缺氧信号在金属诱导的体外和体内毒性中的作用。