Mechanisms of Genomic Instabilities Underlying Two Common Fragile-Site-Associated Loci, PARK2 and DMD, in Germ Cell and Cancer Cell Lines
Mechanisms of Genomic Instabilities Underlying Two Common Fragile-Site-Associated Loci, PARK2 and DMD, in Germ Cell and Cancer Cell Lines
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DOI：
10.1016/j.ajhg.2010.06.006
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发表时间：
2010-07-09
影响因子：
9.8
通讯作者：
Tsuji, Shoji
中科院分区：
文献类型：
--
作者：
Mitsui, Jun;Takahashi, Yuji;Tsuji, Shoji
常见的脆性位点（CFS）是特定的染色体区域，当细胞暴露于DNA复制抑制剂如阿非迪霉素时，这些区域表现出增加的断裂频率。PARK2和DMD分别是常染色体隐性遗传型青少年帕金森病和杜氏和贝克肌营养不良症的致病基因，是两个非常大的基因，位于aphidicolin诱导的CFS内。这两个基因内的总体重排经常被观察到作为这些疾病的致病突变，并且在癌细胞中经常观察到这些基因周围的大的脆性位点内的类似改变。为了阐明这种脆弱性背后的分子机制，我们进行了定制设计的高密度比较基因组杂交分析，以确定生殖细胞系和涉及PARK2或DMD的癌细胞系中约500个断点的连接序列。这些断裂点出现的序列特征在生殖细胞系和癌细胞系中都具有一些相似的特征。对这些结构的详细分析表明，微同源性主要参与重排过程。此外，断裂点聚集区域与最新复制区域和大的核纤层相关结构域相吻合，并且两侧是最高灵活性峰和RIG带边界，这表明影响复制时间的因素共同导致生殖细胞和体细胞系重排的脆弱性。
Common fragile sites (CFSs) are specific chromosome regions that exhibit an increased frequency of breaks when cells are exposed to a DNA-replication inhibitor such as aphidicolin. PARK2 and DMD, the causative genes for autosomal-recessive juvenile Parkinsonism and Duchenne and Becker muscular dystrophy, respectively, are two very large genes that are located within aphidicolin-induced CFSs. Gross rearrangements within these two genes are frequently observed as the causative mutations for these diseases, and similar alterations within the large fragile sites that surround these genes are frequently observed in cancer cells. To elucidate the molecular mechanisms underlying this fragility, we performed a custom-designed high-density comparative genomic hybridization analysis to determine the junction sequences of approximately 500 breakpoints in germ cell lines and cancer cell lines involving PARK2 or DMD. The sequence signatures where these breakpoints occur share some similar features both in germ cell lines and in cancer cell lines. Detailed analyses of these structures revealed that microhomologies are predominantly involved in rearrangement processes. Furthermore, breakpoint-clustering regions coincide with the latest-replicating region and with large nuclear-lamina-associated domains and are flanked by the highest-flexibility peaks and RIG band boundaries, suggesting that factors affecting replication timing collectively contribute to the vulnerability for rearrangement in both germ cell and somatic cell lines.