RELATIONSHIP OF AMPLIFIED DIHYDROFOLATE-REDUCTASE GENES TO DOUBLE MINUTE CHROMOSOMES IN UNSTABLY RESISTANT MOUSE FIBROBLAST CELL-LINES
RELATIONSHIP OF AMPLIFIED DIHYDROFOLATE-REDUCTASE GENES TO DOUBLE MINUTE CHROMOSOMES IN UNSTABLY RESISTANT MOUSE FIBROBLAST CELL-LINES
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DOI：
10.1128/mcb.1.12.1077
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发表时间：
1981-01-01
影响因子：
5.3
通讯作者：
SCHIMKE, RT
中科院分区：
文献类型：
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作者：
BROWN, PC;BEVERLEY, SM;SCHIMKE, RT
当在不存在甲氨蝶呤的情况下培养时，在增加浓度的甲氨蝶呤中选择的小鼠3T6细胞在二氢叶酸还原酶过量产生和甲氨蝶呤抗性方面不稳定。对这些耐药细胞的核型分析揭示了许多双微小染色体的存在。在恢复甲氨蝶呤敏感性过程中，总DNA、富含双小染色体的级分DNA以及每个细胞的双小染色体数量中二氢叶酸还原酶基因序列的丢失观察到基本上相同的动力学。这表明不稳定扩增的基因序列位于双微小染色体上。根据二氢叶酸还原酶含量分类的细胞群分析表明，相对基因扩增和双微小染色体含量成比例相关。
Murine 3T6 cells selected in increasing concentrations of methotrexate were unstable with respect to dihydrofolate reductase overproduction and methotrexate resistance when cultured in the absence of methotrexate. An analysis of the karyotypes of these resistant cells revealed the presence of numerous double minute chromosomes. Essentially identical kinetics were observed for loss of dihydrofolate reductase gene sequences in total DNA, in DNA from fractions enriched in double minute chromosomes and in the numbers of double minute chromosomes per cell during reversion to methotrexate sensitivity. This suggested that unstably amplified gene sequences were localized on double minute chromosomes. An analysis of cell populations sorted according to dihydrofolate reductase enzyme contents showed that relative gene amplification and double minute chromosome content were related proportionally.