Kirschner L S
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Nucleic Acids Res. 1996 Jul 15;24(14):2829-34. doi: 10.1093/nar/24.14.2829.
Mammalian cells that have undergone gene amplification and/or gene rearrangement have been used as resources to gain insight into the questions of chromosome structure and dynamics. The multidrug resistant murine cell line J7.V2-1 has been shown previously to contain two distinct forms of the highly amplified mdr2 gene, a member of the mouse gene family responsible for the multidrug resistant (MDR) phenotype [Kirschner, L. S. (1995) DNA Cell Biol. 14, 47-59]. Characterization of both forms of the gene revealed that one form corresponded to the wild-type structure of the gene, whereas the other represented a rearrangement. Investigation of this altered gene demonstrated a deletion of 1.6 kb of the wild-type sequence, and replacement of this region with a poly(AT) tract that appears to have been generated de novo. Analysis of the native sequence in this region demonstrated the absence of repetitive elements, but was notable for the presence of two long stretches of polypurine: polypyrimidine strand asymmetry. Analysis of mdr2 transcripts in this cell line revealed that nearly all of the mRNA is transcribed from the rearranged form of the gene. This message is unable to code for a functional mdr2 gene product, owing to a deletion of the fourth exon during this event. Mechanisms of the rearrangement, as well as the significance of this curious effect on transcription, are discussed.
已经将经历基因扩增和/或基因重排的哺乳动物细胞用作资源，以深入了解染色体结构和动力学问题。先前已证明多药耐药小鼠细胞系J7.V2-1含有两种不同形式的高度扩增的mdr2基因，该基因是负责多药耐药（MDR）表型的小鼠基因家族的成员[Kirschner, L. S. (1995) DNA Cell Biol. 14, 47-59]。对该基因的两种形式进行表征后发现，一种形式对应于该基因的野生型结构，而另一种则代表重排。对这种改变的基因进行研究表明，野生型序列缺失了1.6 kb，并被一个似乎是从头产生的聚（AT）序列取代。对该区域的天然序列进行分析表明不存在重复元件，但值得注意的是存在两个长的聚嘌呤：聚嘧啶链不对称序列。对该细胞系中mdr2转录本的分析表明，几乎所有的mRNA都是从该基因的重排形式转录而来的。由于在此过程中第四个外显子缺失，这条信息无法编码功能性的mdr2基因产物。本文讨论了重排的机制以及这种奇特的转录效应的意义。
