Ito T, Kabuyama Y, Okazaki S, Kameda T, Murakami M, Iba H
Department of Gene Regulation, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Nucleic Acids Res. 1998 Nov 1;26(21):4868-73. doi: 10.1093/nar/26.21.4868.
We have previously reported that the non-transforming jun D (wild type) gene can acquire transforming activity through spontaneous mutations when it is replicated through avian replication-competent retrovirus vectors in chicken embryo fibroblasts. In two of these spontaneous mutants, T1 and T2, which were isolated from proviral DNA in the same transformed cell clone, a specific 48 bp polynucleotide segment of the jun D coding sequence was tandemly repeated three and five times, respectively. We report here that the number of direct repeats in these mutants rapidly changes (mostly decreases) in the context of either RSV-based replication-competent or MLV-based replication-defective retroviruses, most likely during the process of reverse transcription, while these mutations are stable in the cellular chromosome. We also show that the growth conditions of the infected culture modulate the proportions of polymorphic proviral populations in the infected culture. We finally discuss the possible molecular mechanisms that generate genetic diversity in these amplification mutants.
我们之前曾报道，非转化型Jun D（野生型）基因在通过禽复制能力强的逆转录病毒载体在鸡胚成纤维细胞中复制时，可通过自发突变获得转化活性。在从同一转化细胞克隆的前病毒DNA中分离出的两个自发突变体T1和T2中，Jun D编码序列的一个特定48 bp多核苷酸片段分别串联重复了三次和五次。我们在此报告，在基于劳氏肉瘤病毒（RSV）的复制能力强的逆转录病毒或基于莫洛尼鼠白血病病毒（MLV）的复制缺陷型逆转录病毒的背景下，这些突变体中的直接重复序列数量会迅速变化（大多减少），最有可能发生在逆转录过程中，而这些突变在细胞染色体中是稳定的。我们还表明，感染培养物的生长条件会调节感染培养物中多态性前病毒群体的比例。我们最后讨论了在这些扩增突变体中产生遗传多样性的可能分子机制。
