The human papillomavirus type 16 E7 oncogene is required for the productive stage of the viral life cycle
The human papillomavirus type 16 E7 oncogene is required for the productive stage of the viral life cycle
复制标题
DOI：
10.1128/jvi.74.14.6622-6631.2000
复制
发表时间：
2000-07-01
影响因子：
5.4
通讯作者：
Lambert, PF
中科院分区：
文献类型：
--
作者：
Flores, ER;Allen-Hoffmann, BL;Lambert, PF
人乳头瘤病毒16型（HPV-16）的产生与其感染的宿主上皮细胞的分化密切相关。感染发生在创伤部位的上皮基底层，其中病毒利用宿主DNA复制机制将其自身建立为低拷贝数附加体。HPV-16生命周期的生产阶段发生在上皮细胞的有丝分裂后基底上层，在那里病毒将其DNA扩增到高拷贝数，合成衣壳蛋白（L1和L2），使HPV-16基因组衣壳化，并随着上皮细胞上层脱落而释放病毒粒子颗粒。假设乳头瘤病毒具有克服发生在分化的上皮细胞中的DNA合成阻滞的机制，并且HPV-16 E7癌蛋白已被认为在该过程中发挥作用。为了确定E7是否在HPV-16生命周期中起作用，通过在完整HPV-16基因组的E7基因中插入翻译终止接头（TTL）来创建E7缺陷型HPV-16基因组。将该DNA转染到之前显示支持HPV-16生命周期的永生化人包皮角质形成细胞系中，并获得稳定的细胞系，其具有E7缺陷型HPV-16基因组附加体，正常感染中发现的基因组状态。通过在促进上皮细胞分化的条件下培养这些细胞，我们发现E7是HPV-16生命周期的生产阶段所必需的。缺乏E7的HPV-16无法扩增其DNA，并且表达了病毒生产所需的衣壳蛋白L1的量减少。E7似乎通过干扰角质形成细胞分化程序和诱导宿主DNA复制机制来为HPV-16 DNA合成创造有利环境。这些数据表明，E7在乳头瘤病毒的生命周期中起着重要作用。
The production of the human papillomavirus type 16 (HPV-16) is intimately tied to the differentiation of the host epithelium that it infects. Infection occurs in the basal layer of the epithelium at a site of wounding, where the virus utilizes the host DNA replication machinery to establish itself as a low copy number episome. The productive stage of the HPV-16 life cycle occurs in the postmitotic suprabasal layers of the epithelium, where the virus amplifies its DNA to high copy number, synthesizes the capsid proteins (L1 and L2), encapsidates the HPV-16 genome, and releases virion particles as the upper layer of the epithelium is shed. Papillomaviruses are hypothesized to possess a mechanism to overcome the block in DNA synthesis that occurs in the differentiated epithelial cells, and the HPV-16 E7 oncoprotein has been suggested to play a role in this process. To determine whether E7 plays a role in the HPV-16 life cycle, an E7-deficient HPV-16 genome was created by inserting a translational termination linker (TTL) in the E7 gene of the full HPV-16 genome. This DNA was transfected into an immortalized human foreskin keratinocyte cell line shown previously to support the HPV-16 life cycle, and stable cell lines were obtained that harbored the E7-deficient HPV-16 genome episomally, the state of the genome found in normal infections. By culturing these cells under conditions which promote the differentiation of epithelial cells, we found E7 to be necessary for the productive stage of the HPV-16 life cycle. HPV-16 lacking E7 failed to amplify its DNA and expressed reduced amounts of the capsid protein L1, which is required for virus production. E7 appears to create a favorable environment far HPV-16 DNA synthesis by perturbing the keratinocyte differentiation program and inducing the host DNA replication machinery. These data demonstrate that E7 plays an essential role in the papillomavirus life cycle.