THE ENHANCER OF HUMAN PAPILLOMAVIRUS TYPE-16 - BINDING-SITES FOR THE UBIQUITOUS TRANSCRIPTION FACTOR-OCT-1, FACTOR-NFA, FACTOR-TEF-2, FACTOR-NF1, AND FACTOR-AP-1 PARTICIPATE IN EPITHELIAL CELL-SPECIFIC TRANSCRIPTION
THE ENHANCER OF HUMAN PAPILLOMAVIRUS TYPE-16 - BINDING-SITES FOR THE UBIQUITOUS TRANSCRIPTION FACTOR-OCT-1, FACTOR-NFA, FACTOR-TEF-2, FACTOR-NF1, AND FACTOR-AP-1 PARTICIPATE IN EPITHELIAL CELL-SPECIFIC TRANSCRIPTION
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DOI：
10.1128/jvi.65.11.5933-5943.1991
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发表时间：
1991-11-01
影响因子：
5.4
通讯作者：
BERNARD, HU
中科院分区：
文献类型：
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作者：
CHONG, T;APT, D;BERNARD, HU
人乳头瘤病毒 16 型 (HPV-16) 的增强子被认为对上皮细胞具有特异性，特别是对宫颈癌衍生的细胞系。 我们用完整的增强子以及非重叠的亚克隆重新检验了这一假设，发现所有克隆在源自表皮以及宫颈癌、乳腺癌和结肠癌的上皮细胞系中均具有活性，但在成纤维细胞、淋巴瘤和胚胎癌细胞中均无活性。 尽管该病毒仅感染人粘膜上皮细胞，但增强子活性与转染的上皮细胞的确切类型或来源物种无关。 尽管存在上皮细胞特异性，但我们发现 HPV-16 增强子的活性与巨细胞病毒增强子和猿猴病毒 40 增强子的活性存在很大差异，且具有细胞系依赖性。 这表明增强子元件的数量贡献不同，而不是通过全有或全无开关进行调节。 400 bp 增强子的 91 bp 亚克隆维持了细胞类型特异性。 该片段的大部分增强子活性被普遍存在的因子 AP-1、核因子 1 (NF1) 或 TEF-2 结合位点的替代突变消除。 这三种类型的因子在不合作的情况下结合这个 91 bp 增强子，尽管激活似乎是协同的。 在 91 bp 片段之外，乳头瘤病毒增强子的典型基序，即侧翼有 NF1 结合位点的八聚体序列，有助于增强子功能，因为其删除后活性大大降低。 在 HPV-16 中，该基序与 oct-1 因子以及可能的新因子 NFA 结合，而 HPV-11 的相关基序仅被 NFA 识别。 经检查，参与 HPV 增强子激活的五种转录因子均不限于上皮细胞，但 NF1、AP-1 和 oct-1 在 HeLa 细胞中的浓度高于成纤维细胞。 只有 NF1 显示出一些细胞类型特异性的定性差异。 我们认为 HPV-16 增强子的上皮特异性是通过假定普遍存在的转录因子的结合位点实现的。 这种激活的机制显然涉及浓度不同的因子之间的协同作用，并且可能包括存在于这些因子的 DNA 结合域之外的细胞特异性功能差异。
The enhancer of human papillomavirus type 16 (HPV-16) is considered to be specific for epithelial cells, in particular for cervical carcinoma-derived cell lines. We reexamined this hypothesis with the complete enhancer as well as nonoverlapping subclones and found all clones to be active in epithelial cell lines derived from the epidermis and from carcinomas of the cervix, mammary gland, and colon, but inactive in fibroblast, lymphoma, and embryonal carcinoma cells. Although the virus infects only human mucosal epithelia, enhancer activity was independent of the exact type or of the species of origin of the transfected epithelial cell. In spite of epithelial cell specificity, we found that the activity of the HPV-16 enhancer varied strongly from a cytomegalovirus enhancer and the simian virus 40 enhancer in a cell line-dependent manner. This suggests varying quantitative contributions of enhancer elements rather than regulation by an all-or-none switch. Cell type specificity was maintained by a 91-bp subclone of the 400-bp enhancer. Most of the enhancer activity of this fragment was eliminated by alternative mutations in binding sites for the ubiquitous factors AP-1, nuclear factor 1 (NF1), or TEF-2. These three types of factors bind this 91-bp enhancer without cooperation, although activation appears to be synergistic. Outside the 91-bp fragment, a motif typical for papillomavirus enhancers, namely an octamerlike sequence flanked by an NF1-binding site, contributes to enhancer function, as the activity was strongly reduced upon its deletion. In HPV-16, this motif is bound by the oct-1 factor as well as by a probably novel factor, NFA, whereas a related motif of HPV-11 is recognized only by NFA. On examination, none of the five types of transcription factors involved in HPV enhancer activation was restricted to epithelial cells, but NF1, AP-1, and oct-1 were present in higher concentration in HeLa cells than in fibroblasts. Only NF1 showed some qualitative cell type-specific differences. We propose that the epithelial specificity of the HPV-16 enhancer is brought about via binding sites for supposed ubiquitous transcription factors. The mechanism of this activation apparently involves synergism between factors that vary in concentration and may include cell-specific functional differences residing outside the DNA-binding domain of these factors.