Chromosomal and extrachromosomal localization of amplified dihydrofolate reductase genes in cultured mammalian cells.
Chromosomal and extrachromosomal localization of amplified dihydrofolate reductase genes in cultured mammalian cells.
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培养的哺乳动物细胞中扩增的二氢叶酸还原酶基因的染色体和染色体外定位。
DOI：
10.1101/sqb.1981.045.01.097
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Slate,DL
中科院分区：
文献类型：
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作者：
Schimke,RT;Brown,PC;Kaufman,RJ;McGrogan,M;Slate,DL
先前的报告（Alt等人，1976年；Schimke等人，1978年，1979年）和其他实验室（Fisher，1961年；Hakala等人，1961年；Friedkin等人，1962年；Nakamura和Littlefield，1972年；Biedler和Spengler，1976年；Flintoff等人，1976年；Bostock等人，1976年）的报告。 1979）表明，逐步选择培养的小鼠和仓鼠细胞对叶酸的 4-氨基类似物甲氨蝶呤 (MTX) 的抗性，会导致二氢叶酸还原酶 (DHFR) 水平升高。我们已经证明，DHFR 酶水平升高是由 dhfr 基因数量相应增加所致（即基因扩增；Altet al. 1978；Schimke et al. 1979），并且出现在小鼠和仓鼠来源的许多不同细胞系中，无论核型是否为严重非整倍体或相对正常。当细胞在没有 MTX 的情况下生长时，扩增的 dhfr 基因可以以稳定或不稳定的状态存在（Alt 等人，1978）。基因扩增的发生作为培养动物细胞中获得耐药性的机制并不限于 MTX，因为对天冬氨酰转氨甲酰酶的高度特异性抑制剂 PALA（N-[膦乙酰基-L-天冬氨酸）的耐药性也是由编码该酶的 DNA 序列的扩增引起的（Wahl 等人）等，1979b）。此外，还有各种其他例子，逐步选择高耐药性，无论是稳定的还是不稳定的，导致特定酶的增加；这些现象中的某些现象很可能也是选择性基因扩增的结果（例如，Meuth 和 Green 1974；Baskin 等人 1975；Sinensky 1977）。
Previous reports from this (Alt et al. 1976; Schimke et al. 1978, 1979) and other laboratories (Fisher 1961; Hakala et al. 1961; Friedkin et al. 1962; Nakamura and Littlefield 1972; Biedler and Spengler 1976; Flintoff et al. 1976; Bostock et al. 1979) have shown that stepwise selection of cultured mouse and hamster cells for resistance to the 4-amino analog of folic acid, methotrexate (MTX), results in elevated levels of dihydrofolate reductase (DHFR). We have shown that the elevated DHFR enzyme levels result from a corresponding increase in the number of dhfr genes (ie, gene amplification; Altet al. 1978; Schimke et al. 1979) and occur in a number of different cell lines of both mouse and hamster origin irrespective of whether the karyotype is grossly aneuploid or is relatively normal. The amplified dhfr genes can exist in either a stable or an unstable state when cells are grown in the absence of MTX (Alt et al. 1978).The occurrence of gene amplification as a mechanism for the acquisition of drug resistance in cultured animal cells is not limited to MTX, since resistance to PALA (N-[phosphonacetyll-L-aspartate), a highly specific inhibitor of aspartyltranscarbamylase, also results from amplification of a DNA sequence coding for this enzyme (Wahl et al. 1979b). In addition, there are various other examples of stepwise selection for high drug resistance, either stable or unstable, resulting in increases of specific enzymes; it is likely that certain of these phenomenona are the result of selective gene amplification as well (eg, Meuth and Green 1974; Baskin et al. 1975; Sinensky 1977).