Nakahara Tomomi, Peh Woei Ling, Doorbar John, Lee Denis, Lambert Paul F
McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, 53706, USA.
J Virol. 2005 Oct;79(20):13150-65. doi: 10.1128/JVI.79.20.13150-13165.2005.
The life cycle of human papillomaviruses (HPVs) is tightly linked to the differentiation program of the host's stratified epithelia that it infects. E1(circumflex)E4 is a viral protein that has been ascribed multiple biochemical properties of potential biological relevance to the viral life cycle. To identify the role(s) of the viral E1(circumflex)E4 protein in the HPV life cycle, we characterized the properties of HPV type 16 (HPV16) genomes harboring mutations in the E4 gene in NIKS cells, a spontaneously immortalized keratinocyte cell line that when grown in organotypic raft cultures supports the HPV life cycle. We learned that E1(circumflex)E4 contributes to the replication of the viral plasmid genome as a nuclear plasmid in basal cells, in which we also found E1(circumflex)E4 protein to be expressed at low levels. In the suprabasal compartment of organotypic raft cultures harboring E1(circumflex)E4 mutant HPV16 genomes there were alterations in the frequency of suprabasal cells supporting DNA synthesis, the levels of viral DNA amplification, and the degree to which the virus perturbs differentiation. Interestingly, the comparison of the phenotypes of various mutations in E4 indicated that the E1(circumflex)E4 protein-encoding requirements for these various processes differed. These data support the hypothesis that E1(circumflex)E4 is a multifunctional protein and that the different properties of E1(circumflex)E4 contribute to different processes in both the early and late stages of the virus life cycle.
人乳头瘤病毒（HPV）的生命周期与它所感染的宿主复层上皮的分化程序紧密相连。E1（上标）E4是一种病毒蛋白，它具有多种与病毒生命周期潜在生物学相关性的生化特性。为了确定病毒E1（上标）E4蛋白在HPV生命周期中的作用，我们在NIKS细胞中对E4基因携带突变的16型HPV（HPV16）基因组的特性进行了表征，NIKS细胞是一种自发永生化的角质形成细胞系，当在器官型筏式培养物中生长时，它支持HPV的生命周期。我们了解到，E1（上标）E4作为核质粒在基底细胞中有助于病毒质粒基因组的复制，在基底细胞中我们还发现E1（上标）E4蛋白表达水平较低。在携带E1（上标）E4突变型HPV16基因组的器官型筏式培养物的棘层上部隔室中，支持DNA合成的棘层上部细胞的频率、病毒DNA扩增水平以及病毒干扰分化的程度都发生了改变。有趣的是，对E4中各种突变的表型进行比较表明，这些不同过程对E1（上标）E4蛋白的编码要求有所不同。这些数据支持了这样一种假设，即E1（上标）E4是一种多功能蛋白，并且E1（上标）E4的不同特性在病毒生命周期的早期和晚期都对不同过程有贡献。
