Chromosomal destabilization during gene amplification.
Chromosomal destabilization during gene amplification.
复制标题
基因扩增过程中染色体不稳定。
DOI：
10.1128/mcb.10.6.3056-3066.1990
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发表时间：
1990
影响因子：
5.3
通讯作者：
Wahl,GM
中科院分区：
文献类型：
--
作者：
Ruiz,JC;Wahl,GM
无着丝粒染色体外元件，例如亚微观自主复制环状分子（附加体）和双微小染色体，是许多耐药细胞系和肿瘤细胞系中常见的早期（在某些情况下是初始）基因扩增中间体。为了获得一个更完整的理解的扩增过程中，我们研究了这样的染色体外元素产生的分子机制，我们跟踪这些扩增中间体随着时间的推移的命运。该模型系统由通过基因转移产生的中国仓鼠细胞系（L46）组成，其中最初的扩增产物先前显示为不稳定的染色体外元件，其含有跨越超过160个酶的反向复制（J.C. Ruiz和G. M.沃尔，莫尔。Cell. 8：4302-4313，1988）。在这项研究中，我们表明，这些分子是通过涉及染色体缺失的过程形成的。在多个时间点对具有扩增序列的细胞进行荧光原位杂交。这些研究表明，染色体外分子迅速整合到染色体中，通常在端粒附近或端粒处，并且一旦整合，扩增的序列本身就不稳定。这些数据提供了一个分子和细胞遗传学年表基因扩增在这个模型系统中，早期事件涉及删除产生染色体外元素，这些元素的后续整合沉淀级联的染色体不稳定性。
Acentric extrachromosomal elements, such as submicroscopic autonomously replicating circular molecules (episomes) and double minute chromosomes, are common early, and in some cases initial, intermediates of gene amplification in many drug-resistant and tumor cell lines. In order to gain a more complete understanding of the amplification process, we investigated the molecular mechanisms by which such extrachromosomal elements are generated and we traced the fate of these amplification intermediates over time. The model system consists of a Chinese hamster cell line (L46) created by gene transfer in which the initial amplification product was shown previously to be an unstable extrachromosomal element containing an inverted duplication spanning more than 160 kilobases (J. C. Ruiz and G. M. Wahl, Mol. Cell. Biol. 8:4302-4313, 1988). In this study, we show that these molecules were formed by a process involving chromosomal deletion. Fluorescence in situ hybridization was performed at multiple time points on cells with amplified sequences. These studies reveal that the extrachromosomal molecules rapidly integrate into chromosomes, often near or at telomeres, and once integrated, the amplified sequences are themselves unstable. These data provide a molecular and cytogenetic chronology for gene amplification in this model system; an early event involves deletion to generate extrachromosomal elements, and subsequent integration of these elements precipitates a cascade of chromosome instability.