Sinclair A J, Palmero I, Peters G, Farrell P J
Ludwig Institute for Cancer Research, St. Mary's Hospital Medical School, London, UK.
EMBO J. 1994 Jul 15;13(14):3321-8. doi: 10.1002/j.1460-2075.1994.tb06634.x.
Epstein-Barr virus (EBV) is unusual among DNA tumour viruses in that the virus particle is able to infect and immortalize resting cells with very high efficiency. Mutation of the viral genome has indicated that at least six viral genes (LMP-1 and EBNAs 1, 2, 3A, 3C and LP) are essential for immortalization. We demonstrate that the activation of a G1 cyclin, cyclin D2, is an early event following infection with EBV and that cyclin D2 activation is dependent on the expression of viral genes. The different levels of cyclin D2 transcripts in Burkitt's lymphoma cell lines expressing different subsets of EBV immortalizing genes suggest an involvement of EBNA-2 or EBNA-LP in cyclin D2 regulation. By exposing resting primary B cells to a purified preparation of the EBV surface glycoprotein gp340, we have been able to achieve efficient expression of plasmid DNAs introduced by electroporation. Vectors encoding two viral genes, EBNA-2 and EBNA-LP, are sufficient to activate the expression of cyclin D2 in this system. Thus, the progression of resting B lymphocytes into the G1 phase of the cell cycle can be reconstituted in the absence of virus by the cooperation of two of the six viral genes required for immortalization.
爱泼斯坦-巴尔病毒（EBV）在DNA肿瘤病毒中较为特殊，因为病毒颗粒能够高效感染静止细胞并使其永生化。病毒基因组的突变表明，至少六个病毒基因（LMP-1以及EBNAs 1、2、3A、3C和LP）对于永生化至关重要。我们证明，G1期细胞周期蛋白cyclin D2的激活是EBV感染后的早期事件，且cyclin D2的激活依赖于病毒基因的表达。在表达EBV永生化基因不同亚群的伯基特淋巴瘤细胞系中，cyclin D2转录本的不同水平表明EBNA-2或EBNA-LP参与了cyclin D2的调控。通过将静止的原代B细胞暴露于纯化的EBV表面糖蛋白gp340制剂中，我们得以实现通过电穿孔导入的质粒DNA的高效表达。在该系统中，编码两个病毒基因EBNA-2和EBNA-LP的载体足以激活cyclin D2的表达。因此，在没有病毒的情况下，通过永生化所需的六个病毒基因中的两个基因的协同作用，可以重建静止B淋巴细胞进入细胞周期G1期的过程。
