METALLOTHIONEIN AND CELLULAR PROTECTION

金属硫蛋白和细胞保护

• 批准号: 2155146
• 负责人: ARLAN G. RICHARDSON
• 金额: $ 14.24万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-01-01 至 1995-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2155146
• 关键词: brain metabolism; cadmium; chemical carcinogenesis; cytotoxicity; fusion gene; gene expression; genetic promoter element; genetically modified animals; glutathione; hepatotoxin; laboratory mouse; liver neoplasms; metal poisoning; metallothionein; methylnitrosourea; transferrin

The metallothioneins (MTs) are a group of small, ubiquitous, cysteine- rich proteins that avidly bind heavy metal ions. Because MT binds to and is induced by heavy metal ions, it is generally believed that MT evolved to protect living organisms against the toxicity of heavy metals. However, investigators have argued persuasively that it is unlikely that the primary function of MT is to protect cells against heavy metals. Thus the exact function of MT remains an enigma. Gene transfer studies with mammalian cell lines demonstrate that the over-expression of MT results in the cells becoming resistant to the toxicity of heavy metals and alkylating agents. The latter observation is of interest because alkylating agents are known to be carcinogenic in mammals. Although some correlative data suggests that increased levels of MT also protect tissues in vivo against the toxicity of heavy metals, this association is not always observed. At the present time, there is not information about the potential role MT might play in protecting tissues against the toxic and carcinogenic action of alkylating agents. The objective of this project is to produce transgenic mice that over- express MT and to use these mice to test the following hypothesis: Increased expression of MT will protect an organism from the cytotoxic and carcinogenic action of heavy metals and alkylating agents. The specific aims of this project are as follows: 1. To produce and characterize transgenic mice that carry the human- transferrin promoter fused to the human MT-II(Alpha) gene (phTF/hMT- II(alpha). These transgenic mice will over-express the MT-II(Alpha) gene in liver and brain. 2. To determine if the over-expression of MT protects an organism from the toxicity of heavy metals. The hepatotoxicity of Cd will be compared in phTF/hMT-II(Alpha) transgenic mice and mice without the transgene, and the mechanism responsible for the reduced hepatotoxicity will be studied. 3. To determine if the over-expression of MT protects an organism from carcinogenesis induced by alkylating agents. The ability of N-nitroso-N- methylurea(NMU) to induce liver tumors in phTF/hMT-II(Alpha) transgenic mice and mice without the transgene will be compared, and the mechanism responsible for the reduced hepatocarcinogenesis will be studied.

金属硫蛋白（MT）是一组小的，普遍存在的，半胱氨酸- 丰富的蛋白质，能与重金属离子结合。 因为MT与 由于MT是由重金属离子诱导的，因此一般认为MT是由 保护生物体免受重金属的毒害。 然而，调查人员令人信服地认为， MT的主要功能是保护细胞免受重金属的侵害。 因此，MT的确切功能仍然是一个谜。 基因转移研究 与哺乳动物细胞系的研究表明， 导致细胞对重金属的毒性产生抵抗力 和烷基化剂。 后一种观察是有意义的，因为 已知烷化剂在哺乳动物中是致癌的。 尽管一些 相关数据表明，MT水平的增加也可以保护 组织在体内对抗重金属的毒性，这种关联 并不总是遵守。 目前，没有任何信息 关于MT在保护组织免受 烷化剂的毒性和致癌作用。 该项目的目标是生产出能够过度生长的转基因小鼠。 表达MT，并使用这些小鼠来测试以下假设： MT的表达增加将保护生物体免受细胞毒性的影响。 以及重金属和烷化剂的致癌作用。 的 该项目的具体目标如下： 1. 生产和鉴定携带人类- 转铁蛋白启动子与人MT-II（α）基因融合（phTF/hMT-1）。 II（alpha）. 这些转基因小鼠将过度表达MT-II（Alpha）基因 在肝脏和大脑中。 2. 为了确定MT的过表达是否能保护生物体免受 重金属的毒性。 比较镉的肝毒性 在phTF/hMT-II（α）转基因小鼠和没有转基因的小鼠中，和 将研究导致肝毒性降低的机制。 3. 为了确定MT的过表达是否能保护生物体免受 由烷化剂诱发的致癌作用。 N-亚硝基-N- 甲基脲（NMU）诱导phTF/hMT-II（α）转基因小鼠肝肿瘤 小鼠和没有转基因的小鼠将进行比较， 将研究减少肝癌发生的原因。