Tan S H, Bartsch D, Schwarz E, Bernard H U
Institute of Molecular and Cell Biology, National University of Singapore, Republic of Singapore.
J Virol. 1998 May;72(5):3610-22. doi: 10.1128/JVI.72.5.3610-3622.1998.
The gene functions, transcriptional regulation, and genome replication of human papillomaviruses (HPVs) have been extensively studied. Thus far, however, there has been little research on the organization of HPV genomes in the nuclei of infected cells. As a first step to understand how chromatin and suprachromatin structures may modulate the life cycles of these viruses, we have identified and mapped interactions of HPV DNAs with the nuclear matrix. The endogenous genomes of HPV type 16 (HPV-16) which are present in SiHa, HPKI, and HPKII cells, adhere in vivo to the nuclear matrixes of these cell lines. A tight association with the nuclear matrix in vivo may be common to all genital HPV types, as the genomes of HPV-11, HPV-16, HPV-18, and HPV-33 showed high affinity in vitro to preparations of the nuclear matrix of C33A cells, as did the well-known nuclear matrix attachment region (MAR) of the cellular beta interferon gene. Affinity to the nuclear matrix is not evenly spread over the HPV-16 genome. Five genomic segments have strong MAR properties, while the other parts of the genome have low or no affinity. Some of the five MARs correlate with known cis-responsive elements: a strong MAR lies in the 5' segment of the long control region (LCR), and another one lies in the E6 gene, flanking the HPV enhancer, the replication origin, and the E6 promoter. The strongest MAR coincides with the E5 gene and the early-late intergenic region. Weak MAR activity is present in the E1 and E2 genes and in the 3' part of L2. The in vitro map of MAR activity appears to reflect MAR properties in vivo, as we found for two selected fragments with and without MAR activity. As is typical for many MARs, the two segments with highest affinity, namely, the 5' LCR and the early-late intergenic region, have an extraordinarily high A-T content (up to 85%). It is likely that these MARs have specific functions in the viral life cycle, as MARs predicted by nucleotide sequence analysis, patterns of A-T content, transcription factor YY1 binding sites, and likely topoisomerase II cleavage sites are conserved in similar positions throughout all genital HPVs.
人乳头瘤病毒（HPV）的基因功能、转录调控及基因组复制已得到广泛研究。然而，迄今为止，关于HPV基因组在受感染细胞核内的组织形式的研究却很少。作为了解染色质和超染色质结构如何调节这些病毒生命周期的第一步，我们已鉴定并绘制了HPV DNA与核基质的相互作用。SiHa、HPKI和HPKII细胞中存在的16型HPV（HPV - 16）内源性基因组在体内与这些细胞系的核基质黏附。体内与核基质的紧密关联可能是所有生殖道HPV类型共有的特征，因为HPV - 11、HPV - 16、HPV - 18和HPV - 33的基因组在体外对C33A细胞核基质制剂表现出高亲和力，细胞β干扰素基因的著名核基质附着区域（MAR）也是如此。对核基质的亲和力在HPV - 16基因组上分布不均。五个基因组片段具有很强的MAR特性，而基因组的其他部分亲和力较低或没有亲和力。五个MAR中的一些与已知的顺式反应元件相关：一个强MAR位于长控制区（LCR）的5'片段，另一个位于E6基因，位于HPV增强子、复制起点和E6启动子两侧。最强的MAR与E5基因和早晚期基因间隔区重合。E1和E2基因以及L2的3'部分存在弱MAR活性。MAR活性的体外图谱似乎反映了体内的MAR特性，正如我们对两个具有和不具有MAR活性的选定片段所发现的那样。正如许多MAR的典型情况一样，亲和力最高的两个片段，即5' LCR和早晚期基因间隔区，具有极高的A - T含量（高达85%）。这些MAR很可能在病毒生命周期中具有特定功能，因为通过核苷酸序列分析、A - T含量模式、转录因子YY1结合位点以及可能的拓扑异构酶II切割位点预测的MAR在所有生殖道HPV的相似位置都是保守的。
