Trans‐activation of an upstream early gene promoter of bovine papilloma virus‐1 by a product of the viral E2 gene.
Trans‐activation of an upstream early gene promoter of bovine papilloma virus‐1 by a product of the viral E2 gene.
复制标题
病毒 E2 基因产物对牛乳头状瘤病毒-1 上游早期基因启动子的反式激活。
作者：
T. Haugen;T. Cripe;Gordon;D. Ginder;M. Karin;L. Turek
牛乳头瘤病毒-1 (BPV-1) 大约 1000 个核苷酸长的上游调节区 (URR) 包含一个顺式元件，该元件可响应病毒 E2 开放阅读框 (ORF) 中编码的扩散因子的反式激活。一系列 URR DNA 片段已与两个异源基因、细菌氯霉素乙酰转移酶 (cat) 或单纯疱疹病毒-1 胸苷激酶 (tk) 连接，并在瞬时转染试验中测试了在真正的上游早期病毒启动子 P89 处启动的转录。当 E2 反式激活基因产物存在时，P89 启动子的转录活性大大提高。 P89 的 E2 响应顺式元件 (E2R) 已被定位到转录起始位点（BPV 核苷酸 89）上游的序列 ‐277 至 ‐131 核苷酸。在E2基因产物存在但不存在的情况下，E2R元件与SV40早期或tk启动子顺式发挥作为强转录增强子的作用。然而，一些缺乏与 E2R 元件相关序列的异源启动子在瞬时共转染中也被 BPV-1 E2 ORF 中编码的功能反式激活，尽管程度要小得多。因此，除了激活早期病毒基因转录之外，E2 调控基因还可能具有改变细胞基因表达的潜力。
The approximately 1000 nucleotide long upstream regulatory region (URR) of bovine papilloma virus‐1 (BPV‐1) contains a cis element which responds to trans‐activation by a diffusible factor encoded in the viral E2 open reading frame (ORF). A series of URR DNA fragments have been linked to two heterologous genes, bacterial chloramphenicol acetyl transferase (cat) or herpes simplex virus‐1 thymidine kinase (tk), and tested in transient transfection assays for transcription initiating at the authentic upstream early viral promoter, P89. Transcriptional activity of the P89 promoter was greatly elevated in the presence of the E2 trans‐activator gene product. The E2‐responsive cis element (E2R) of P89 has been mapped to sequences ‐277 to ‐131 nucleotides upstream from the transcription start site (BPV nucleotide 89). The E2R element functioned as a strong transcriptional enhancer in cis with the SV40 early or the tk promoter in the presence, but not in the absence, of the E2 gene product. However, several heterologous promoters which lack sequences related to the E2R element were also trans‐activated in transient cotransfections by a function encoded in the E2 ORF of BPV‐1, albeit to a much lesser extent. In addition to activation of early viral gene transcription, the E2 regulatory gene(s) may therefore have the potential to alter cellular gene expression.