Ten Hagen K G, Ravnan J B, Cohen S N
Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305-5120, USA.
J Mol Biol. 1995 Nov 24;254(2):119-29. doi: 10.1006/jmbi.1995.0605.
Bovine papillomavirus (BPV) previously has been reported to exist in transformed rodent cell lines as both chromosomally integrated and extrachromosomal forms. In the BPV-transformed mouse cell line ID13, extrachromosomal BPV molecules replicate throughout S phase of the cell cycle in a random choice mode. We report here that these replication properties were altered for chromosomally integrated BPV DNA in five independent ID13 subclones. In all of the subclones, the integrated BPV sequences, which had no detectable deletions or mutations, existed in head-to-tail tandem arrays that replicated once per cell cycle, predominantly late in S phase. In contrast, extrachromosomal BPV molecules present in other subclones of the same cell line replicated in the random choice mode observed previously for non-integrated BPV. Our results indicate that the replication origin of integrated BPV either is inactivated as a consequence of chromosomal insertion, leading to the replication of BPV from origins in the flanking chromosomal DNA, or alternatively is reprogrammed to function in a once-per-cell cycle mode predominantly late in S phase.
牛乳头瘤病毒（BPV）此前已有报道称，其以染色体整合形式和染色体外形式存在于转化的啮齿动物细胞系中。在BPV转化的小鼠细胞系ID13中，染色体外BPV分子在细胞周期的整个S期以随机选择模式进行复制。我们在此报告，在五个独立的ID13亚克隆中，染色体整合的BPV DNA的这些复制特性发生了改变。在所有亚克隆中，整合的BPV序列没有可检测到的缺失或突变，以头对头串联阵列形式存在，每个细胞周期复制一次，主要在S期后期。相比之下，同一细胞系其他亚克隆中存在的染色体外BPV分子以先前观察到的非整合BPV的随机选择模式进行复制。我们的结果表明，整合BPV的复制起点要么由于染色体插入而失活，导致BPV从侧翼染色体DNA中的起点进行复制，要么被重新编程以在每个细胞周期一次的模式下发挥作用，主要在S期后期。
