Rowe M, Peng-Pilon M, Huen D S, Hardy R, Croom-Carter D, Lundgren E, Rickinson A B
Institute of Cancer Studies, University of Birmingham Medical School, United Kingdom.
J Virol. 1994 Sep;68(9):5602-12. doi: 10.1128/JVI.68.9.5602-5612.1994.
An ability of the Epstein-Barr virus latent membrane protein LMP1 to enhance the survival of infected B cells through upregulation of the bcl-2 oncogene was first suggested by experiments involving gene transfection and the selection of stable LMP1+ clones (S. Henderson, M. Rowe, C. Gregory, F. Wang, E. Kieff, and A. Rickinson, Cell 65:1107-1115, 1991). However, it was not possible to ascertain whether Bcl-2 upregulation was a specific consequence of LMP1 expression or an artifact of the selection procedure whereby rare Bcl-2+ cells already present in the starting population might best be able to tolerate the potentially toxic effects of LMP1. We therefore reexamined this issue by using two different experimental approaches that allowed LMP1-induced effects to be monitored immediately following expression of the viral protein and in the absence of selective pressures; activation of the NF-kappa B transcription factor and upregulation of the cell adhesion molecule ICAM-1 were used as early indices of LMP1 function. In the first approach, stable clones of two B-cell lines carrying an LMP1 gene under the control of an inducible metallothionein promoter were induced to express LMP1 in all cells. Activation of NK-kappa B and upregulation of ICAM-1 occurred within 24 h and were followed at 48 to 72 h by upregulation of Bcl-2. In the second approach, we tested the generality of this phenomenon by transiently expressing LMP1 from a strong constitutively active promoter in a range of different cell types. All six B-cell lines tested showed NF-kappa B activation in response to LMP1 expression, and this was followed in five of six lines by expression of ICAM-1 and Bcl-2. In the same experiments, all three non-B-cell lines showed NF-kappa B activation and ICAM-1 upregulation but never any effect upon Bcl-2. We therefore conclude that Bcl-2 upregulation is part of the panoply of cellular changes induced by LMP1 but that the effect is cell type specific. Our data also suggest that whilst NF-kappa B may be an essential component of LMP1 signal transduction, other cell-specific factors may be required to effect some functions of the viral protein.
爱泼斯坦-巴尔病毒潜伏膜蛋白LMP1通过上调bcl-2癌基因来增强受感染B细胞存活的能力，这一观点最初是由涉及基因转染和稳定LMP1+克隆筛选的实验提出的（S. 亨德森、M. 罗、C. 格雷戈里、F. 王、E. 基夫和A. 里金森，《细胞》65:1107 - 1115，1991年）。然而，无法确定Bcl-2上调是LMP1表达的特定结果，还是筛选过程中的人为因素导致的，即起始群体中已经存在的罕见Bcl-2+细胞可能最能耐受LMP1的潜在毒性作用。因此，我们通过使用两种不同的实验方法重新审视了这个问题，这两种方法能够在病毒蛋白表达后立即且在没有选择压力的情况下监测LMP1诱导的效应；NF-κB转录因子的激活和细胞黏附分子ICAM-1的上调被用作LMP1功能的早期指标。在第一种方法中，将两个携带在可诱导金属硫蛋白启动子控制下的LMP1基因的B细胞系的稳定克隆诱导在所有细胞中表达LMP1。NF-κB的激活和ICAM-1的上调在24小时内发生，在48至72小时后Bcl-2上调。在第二种方法中，我们通过在一系列不同细胞类型中从强组成型活性启动子瞬时表达LMP1来测试这一现象的普遍性。所有六个测试的B细胞系都显示出对LMP1表达的NF-κB激活，并且在六个细胞系中的五个中随后出现了ICAM-1和Bcl-2的表达。在相同的实验中，所有三个非B细胞系都显示出NF-κB激活和ICAM-1上调，但对Bcl-2从未有任何影响。因此，我们得出结论，Bcl-2上调是LMP1诱导的一系列细胞变化的一部分，但这种效应具有细胞类型特异性。我们的数据还表明，虽然NF-κB可能是LMP1信号转导的重要组成部分，但可能需要其他细胞特异性因子来实现病毒蛋白的某些功能。
