Molecular mechanism of the high incidence of cancer of Bloom's syndrome

布卢姆综合征癌症高发的分子机制

基本信息

批准号：
11138207
负责人：
ENOMOTO Takemi
金额：
$ 4.8万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11138207/
关键词：
Bloom's syndrome BLM SCE yeast SGS1 SUMO-1 targeted integration

项目摘要

Bloom's syndrome (BS) is a rare genetic disorder and the cells from BS patients show genomic instability and an increased level of sister chromatid exchange (SCE). We analyzed the functions of yeast Sgs 1, which is the yeast homologue for BLM, as well as those of BLM in higher eukaryotic cells and obtained the following results.1. We made mutated SGS1 genes coding a protein having equivalent missense mutations of BS patients and found that none of the mutated genes could suppress the higher sensitivity to MMS and HU and the elevated SCE of sgs 1 disruptants. Analyses of Sgs 1 functions indicated that the two different mechanisms are operated in Sgs 1 functions, one requiring DNA helicase activity and one not. In addition, genetic analyses indicated that Sgs 1 functions in the down stream of Mec 1 and the upstream of Rad 51.2. We generated a monoclonal antibody specifically recognizing BLM protein and using this antibody, found that BLM is localized in speckled structures in the nucleus. We also obtained a piece of evidence indicating that BLM is associated with SUMO-1. Deletion experiments indicated that the amino acid region 238-586 of BLM is required for the localization in speckled structures.3. We generated BLM^<-/-> and BLM^<-/->/RAD54^<-/-> DT40 cells from the chicken B lymphocyte line DT40 and found that SCE and targeted integration frequencies were increased remarkably in BLM^<-/-> cells. The results obtained with BLM^<-/->/RAD54^<-/-> cells indicated that a large portion of the SCE in BLM^<-/-> cells occurs via homologous recombination and more double strand breaks occur during DNA replication in the absence of BLM and some of these breaks are repaired by homologous recombination.

Bloom综合征（BS）是一种罕见的遗传疾病，BS患者的细胞显示出基因组不稳定性和姊妹染色单体交换（SCE）的水平升高。我们分析了酵母SGS 1的功能，该功能是BLM的酵母同源物以及较高真核细胞中BLM的功能，并获得了以下结果。1。我们制作了编码具有BS患者等效错义突变的蛋白质的突变SGS1基因，发现突变基因都无法抑制对MMS和HU的更高敏感性以及SGS 1中断因子的SCE升高。 SGS 1函数的分析表明，这两种不同的机制在SGS 1功能中运行，一种需要DNA解旋酶活性，而一种不需要。此外，遗传分析表明，SGS 1在MEC 1的向下流和RAD 51.2的上游中的功能。我们产生了一种特异性识别BLM蛋白并使用该抗体的单克隆抗体，发现BLM位于核中的斑点结构中。我们还获得了一个证据，表明BLM与SUMO-1有关。缺失实验表明，BLM的氨基酸区域238-586是斑点结构中的定位。3。我们从鸡B淋巴细胞系DT40产生了BLM^< - / - >和BLM^< - >/ - >/ - >/ - >/ - >/ - >/ - >/ - >/ - > DT40细胞，发现SCE和靶向的积分频率在BLM^< - / - >细胞中显着增加。用BLM^< - / - >/rad54^< - / - >细胞获得的结果表明，BLM^< - / - >细胞中很大一部分SCE通过同源重组发生，并且在没有BLM的情况下进行DNA复制过程中发生了更多的双链断裂，并且这些断裂的某些断裂是由本质重组修复的。