Molecular cloning of the gene for cancer-prone syndrome characterized by abnormal mitotic spindle checkpoint.

以异常有丝分裂纺锤体检查点为特征的易癌综合征基因的分子克隆。

基本信息

批准号：
14370776
负责人：
MATSUURA Shinya
金额：
$ 8.83万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Cancer-prone syndrome of premature chromatid separation with mosaic variegated aneuploidy (PCS syndrome) is a rare autosomal recessive disorder characterised by growth retardation, microcephaly, childhood cancer, premature chromatid separation of all chromosomes and mosaicism for various trisomies and monosomies. Biallelic BUB1B mutations were recently reported in five of eight families with MVA syndrome (probably identical to the PCS syndrome). We here describe molecular analysis of BUB1B (encoding BubR1) in seven Japanese families with the PCS syndrome. Monoallelic BUB1B mutations were found in all seven families studied : a single base deletion (1833delT) in four families ; and a splice site mutation, a nonsense mutation, and a missense mutation in one family each. Transcripts derived from the patients with the 1833delT mutation and the splice site mutation were significantly reduced due to nonsense-mediated mRNA decay. No mutation was found in the second alleles in the seven families studied, but RT-PCR of BUB1B and Western blot and haplotype analysis of BubR1 indicated a modest decrease of their transcripts. BubR1 in the cells from two patients showed both reduced protein expression and diminished kinetochore localization. Their expression level of p55cdc, a specific activator of anaphase-promoting complex, was normal but its kinetochore association was abolished. Microcell-mediated transfer of chromosome 15 (containing BUB1B) into the cells restored normal BubR1 levels, kinetochore localization of p55cdc, and the normal responses to colcemid treatment. These findings indicate the involvement of BubR1 in p55cdc-mediated mitotic checkpoint signaling, and suggest that >50% decrease in expression (or activity) of BubR1 is involved in the PCS syndrome.

与马赛克杂色的非整倍性（PCS综合征）的早产染色质素分离的癌症综合征是一种罕见的常染色体隐性膜疾病，其特征是生长迟缓，小头畸形，儿童癌，早期的染色体分离所有染色体和各种软骨粒和单子层的所有染色体和种植体的分离。最近在八个患有MVA综合征的家族中有五个（可能与PCS综合征相同）中有五个Bub1b突变。我们在这里描述了七个患有PCS综合征的日本家庭中BUB1B（编码BUBR1）的分子分析。在所有研究的七个家庭中都发现了单相关的Bub1b突变：四个家庭中的一个基本缺失（1833delt）；以及一个剪接部位突变，胡说八道的突变和一个家庭中的错义突变。由于胡说八道介导的mRNA衰变，源自1833DELT突变和剪接部位突变的患者的转录本显着降低。在所研究的七个家族的第二个等位基因中未发现突变，但是BUB1B和Western blot的RT-PCR和BUBR1的单倍型分析表明其转录本的减少适度。来自两名患者的细胞中的BUBR1均显示蛋白质表达降低和动力学定位降低。它们的表达水平是p55CDC的表达水平，这是一种促成后期的复合物的特定活化剂，但其动力学的关联被废除了。 Microcell介导的15染色体（包含BUB1B）转移到细胞中，恢复了正常BUBR1水平，p55CDC的动力学定位以及对Colcemid治疗的正常反应。这些发现表明BUBR1参与p55CDC介导的有丝分裂检查点信号传导，并表明PCS综合征涉及BUBR1的表达（或活性）降低> 50％。