Identification of a genetically high-risk group for cadmium toxicity

镉中毒遗传高危人群的鉴定

基本信息

批准号：
13557215
负责人：
NAGANUMA Akira
金额：
$ 8.9万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Metallothionein (MT), the synthesis of which is induced by heavy metals such as cadmium (Cd), binds tightly with these heavy metals and suppress their toxicity. In healthy people, Cd mainly accumulates in the kidney, which is the primary target of Cd toxicity, and is present as MT-bound non-toxic forms. However, the possibility of the presence of a group of people with abnormalities of MT synthesis (high-risk group) cannot be excluded. In this study, therefore, we directed attention to gene mutations as possible causes of abnormal MT synthesis, and evaluated the relationship between abnormal base sequences in the promoter region of MT gene and MT synthesis. When we examined mutations of the promoter region using DNA isolated from white blood cells of 119 healthy Japanese people by the SSCP method, only the one-base substitution from adenine (A) to guanine (G) at the 5th base upstream (-5) of the starting point of transcription (+1), which we detected before, was observed again. Concerning the frequency of its occurrence, the homozygote of adenine, which is the wild type, was observed in 98 subjects (82.4%), heterozygotes of adenine and guanine were observed in 20(16.8%), and the homozygote of guanine was observed in 1(0.8%). This mutant site was present in the core promoter region between TATA box and the starting point of transcription, and the mutant promoter (-5G) had significantly less transcription activating efficiency by Zn and Cd than the wild type (-5A). We also evaluated a simple method for identification of people with a mutation in the promoter and established the fragment length measurement method based on the disappearance of the site that is cut by the restriction enzyme BsgI due to mutation. This identification of a high-risk group for Cd toxicity by this method may allow early prevention of Cd poisoning.

金属硫蛋白（MT）是由镉（CD）等重金属诱导的合成，与这些重金属紧密结合并抑制其毒性。在健康的人中，CD主要积聚在CD毒性的主要目标中，并以MT结合的无毒形式存在。但是，不能排除一群患有MT合成异常（高风险群体）的人的可能性。因此，在这项研究中，我们将注意力集中在基因突变上是异常MT合成的可能原因，并评估了MT基因和MT合成的启动子区域中异常碱基序列之间的关系。当我们使用SSCP方法从119位健康日本人的白细胞中分离出启动子区域的突变，仅在转录（+1）的上游（-5）上游（-5）上从腺嘌呤（a）到鸟嘌呤（g）的一基碱基替代（a），我们之前又经过了我们之前检测到的。关于其发生的频率，在98名受试者（82.4％）中观察到了腺嘌呤的纯合子，在20名受试者中观察到腺嘌呤和鸟嘌呤的杂合子，在20（16.8％）中观察到腺嘌呤和鸟嘌呤的纯合子，在1（0.8％）中观察到鸟嘌呤的纯合子。该突变位点存在于塔塔盒和转录起点之间的核心启动子区域中，而突变体启动子（-5G）的转录激活效率明显少于野生型（-5a）。我们还评估了一种鉴定启动子中突变的人的简单方法，并根据位点的消失建立了片段长度测量方法，该方法是由于突变引起的限制酶BSGI所切割的。通过这种方法对高危组的CD毒性识别可能会允许尽早预防CD中毒。