Rochford R, Villarreal L P
Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.
J Virol. 1991 Apr;65(4):2108-12. doi: 10.1128/JVI.65.4.2108-2112.1991.
The regulatory DNA (enhancer) of polyomavirus (Py) is a major determinant of tissue-specific DNA replication during acute infection of newborn mice. Previously, we reported that the combination of one of the two Py enhancers (A enhancer) and the repeated Moloney murine leukemia virus (Mo-MuLV) enhancer gave a chimeric Py genome (Py-MuLV) that replicates predominantly in the acinar cells of the pancreas, a tissue not permissive for wild-type PyA2 replication (R. Rochford, B. A. Campbell, and L. P. Villareal. Proc. Nat. Acad. Sci. USA 84:449-453,1987). In this report, we further examine the combined enhancer requirements for acinar cell-specific Py replication. We also compare enhancer requirements for Py replication in the acinar cells of the pancreas with those of a transformed acinar cell line (266-6 cells). The deletion of sequences within the A enhancer of Py-MuLV (nucleotides 5098 to 5132) results in a virus with 10-fold-reduced levels of pancreas-specific replication. The deletion, however, of one of the 72-bp repeated Mo-MuLV enhancer sequences from Py-MuLV results in a complete loss of pancreas-specific DNA replication. Thus, the Py A enhancer is required for efficient replication of Py in the pancreas without otherwise altering organ specificity, but both of the repeated copies of the Mo-MuLV enhancer are essential for pancreas-specific Py replication. In contrast to the enhancer requirements for in vivo pancreas replication, in transformed acinar cells (266-6), PyA2 wild-type replicated efficiently and the Py-MuLV recombinant replicated inefficiently. These data suggest that the cell-specific control of DNA replication is different between normal pancreas cells and their transformed cell line counterparts and that this difference is apparent in the enhancer requirement of cell-specific Py DNA replication.
多瘤病毒（Py）的调控DNA（增强子）是新生小鼠急性感染期间组织特异性DNA复制的主要决定因素。此前，我们报道过，两个Py增强子之一（A增强子）与重复的莫洛尼鼠白血病病毒（Mo-MuLV）增强子相结合，产生了一种嵌合Py基因组（Py-MuLV），其主要在胰腺腺泡细胞中复制，而胰腺是野生型PyA2复制不允许的组织（R. 罗奇福德、B. A. 坎贝尔和L. P. 比利亚雷亚尔。《美国国家科学院院刊》84:449 - 453，1987年）。在本报告中，我们进一步研究了腺泡细胞特异性Py复制对增强子的联合需求。我们还比较了胰腺腺泡细胞中Py复制对增强子的需求与转化腺泡细胞系（266 - 6细胞）中Py复制对增强子的需求。Py-MuLV的A增强子内序列缺失（核苷酸5098至5132）导致一种病毒，其胰腺特异性复制水平降低10倍。然而，从Py-MuLV中删除72碱基对重复的Mo-MuLV增强子序列之一会导致胰腺特异性DNA复制完全丧失。因此，Py A增强子是Py在胰腺中高效复制所必需的，且不会改变器官特异性，但Mo-MuLV增强子的两个重复拷贝对于胰腺特异性Py复制都是必不可少的。与体内胰腺复制对增强子的需求相反，在转化的腺泡细胞（266 - 6）中，PyA2野生型能高效复制，而Py-MuLV重组体复制效率低下。这些数据表明，正常胰腺细胞与其转化细胞系对应物之间DNA复制的细胞特异性控制是不同的，并且这种差异在细胞特异性Py DNA复制对增强子的需求中很明显。
