Roles of the E6 and E7 proteins in the life cycle of low-risk human papillomavirus type 11
Roles of the E6 and E7 proteins in the life cycle of low-risk human papillomavirus type 11
复制标题
DOI：
10.1128/jvi.78.5.2620-2626.2004
复制
发表时间：
2004-03-01
影响因子：
5.4
通讯作者：
Laimins, LA
中科院分区：
文献类型：
--
作者：
Oh, ST;Longworth, MS;Laimins, LA
高危型人乳头瘤病毒（HPV）E6和E7蛋白具有许多重要功能，包括与p53的结合和降解以及与Rb蛋白的相互作用。相反，低风险E6和E7蛋白的生理作用仍不清楚。先前的研究表明，高风险的E6和E7蛋白也通过促进病毒附加体的维持而在生产性生命周期中发挥作用（J. T.托马斯，W. G.休伯特，M. N. Ruesch和L. A. Laimins，Proc. Natl. Acad. Sci. USA 96：8449-8454，1999）。为了确定低风险E6或E7是否同样是稳定维持游离体所必需的，构建了在E6或E7中含有翻译终止突变的HPV 11型（HPV-11）基因组。在转染到正常人角质形成细胞中后，E6功能被取消的基因组不能以附加体方式维持。在高危型和低危型HPV中保守的氨基酸中含有取代突变的基因组的转染表明，多个蛋白质结构域参与了这一过程。检查转染HPV-11基因组的细胞，其中E7功能被抑制，发现表现出更复杂的表型。在转染后的第二次传代中，突变体基因组保持为游离体，但水平显著低于用野生型HPV-11基因组转染的细胞。然而，在培养物中进一步传代后，这些E7突变体基因组的附加体形式迅速消失。这些发现确定了低风险E6和E7蛋白在低风险HPV-11基因组的附加型维持中的重要新功能，并表明它们可能以与观察到的高风险蛋白相似的方式起作用。
Many important functions have been attributed to the high-risk human papillomavirus (HPV) E6 and E7 proteins, including binding and degradation of p53 as well as interacting with Rb proteins. In contrast, the physiological roles of the low-risk E6 and E7 proteins remain unclear. Previous studies demonstrated that the high-risk E6 and E7 proteins also play roles in the productive life cycle by facilitating the maintenance of viral episomes (J. T. Thomas, W. G. Hubert, M. N. Ruesch, and L. A. Laimins, Proc. Natl. Acad. Sci. USA 96:8449-8454, 1999). In order to determine whether low-risk E6 or E7 is similarly necessary for the stable maintenance of episomes, HPV type 11 (HPV-11) genomes that contained translation termination mutations in E6 or E7 were constructed. Upon transfection into normal human keratinocytes, genomes in which E6 function was abolished were unable to be maintained episomally. Transfection of genomes containing substitution mutations in amino acids conserved in high- and low-risk HPV types suggested that multiple protein domains are involved in this process. Examination of cells transfected with HPV-11 genomes in which E7 function was inhibited were found to exhibit a more complex phenotype. At the second passage following transfection, mutant genomes were maintained as episomes but at significantly reduced levels than in cells transfected with the wild-type HPV-11 genome. Upon further passage in culture, however, the episomal forms of these E7 mutant genomes quickly disappeared. These findings identify important new functions for the low-risk E6 and E7 proteins in the episomal maintenance of low-risk HPV-11 genomes and suggest that they may act in a manner similar to that observed for the high-risk proteins.