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）等重金属诱导合成的，与这些重金属紧密结合并抑制其毒性。在健康人中，Cd 主要积聚在肾脏中，肾脏是 Cd 毒性的主要目标，并以 MT 结合的无毒形式存在。但不能排除存在MT合成异常人群（高危人群）的可能性。因此，在本研究中，我们将注意力集中在导致MT合成异常的可能原因的基因突变上，并评估了MT基因启动子区的异常碱基序列与MT合成之间的关系。当我们使用从 119 名健康日本人的白细胞中通过 SSCP 方法分离的 DNA 检测启动子区域的突变时，仅在上游第 5 个碱基 (-5) 处从腺嘌呤 (A) 变为鸟嘌呤 (G) 的一碱基替换我们之前检测到的转录起始点（+1）再次被观察到。关于其出现频率，腺嘌呤纯合子（野生型）在98名受试者（82.4％）中观察到，腺嘌呤和鸟嘌呤杂合子在20名受试者（16.8％）中观察到，鸟嘌呤纯合子在20名受试者中观察到。 1（0.8%）。该突变位点存在于TATA盒和转录起始点之间的核心启动子区域，并且突变启动子(-5G)的Zn和Cd转录激活效率显着低于野生型(-5A)。我们还评估了一种识别启动子突变者的简单方法，并建立了基于因突变而被限制性酶 BsgI 切割的位点消失的片段长度测量方法。通过这种方法识别镉中毒的高危人群可能有助于早期预防镉中毒。