Daibata M, Speck S H, Mulder C, Sairenji T
Department of Pharmacology, University of Massachusetts Medical School, Worcester 01655.
Virology. 1994 Feb;198(2):446-54. doi: 10.1006/viro.1994.1056.
Initiation of the Epstein-Barr virus (EBV) lytic cycle is dependent on the transcription of the BZLF1 gene. The BZLF1 gene promoter (Zp) was activated by crosslinking of cell surface immunoglobulin (Ig) with anti-Ig antibody in B cells, even in the absence of other viral genes. We identified several anti-Ig response elements within Zp, which were originally defined as 12-O-tetradecanoylphorbol-13-acetate (TPA) response elements (ZI repeats and ZII, an AP-1-like domain). Since anti-Ig crosslinking leads to activation of protein kinase C (PKC) and an increase in intracellular calcium level, Zp was tested for the response to these cellular factors. Treatment with calcium ionophore A23187 increased Zp activity. When the calcium ionophore was used in conjunction with TPA, a PKC activator, the Zp induction was synergistically enhanced. 1-(5-Isoquinolinyl sulfonyl)-2-methylpiperazine, an inhibitor of PKC, inhibited the anti-Ig inducibility of Zp. Calmodulin antagonists, compound R24571 and trifluoperazine, blocked the Zp activation with anti-Ig. These findings suggest that Zp responds directly to changes in the activity of both PKC and calcium/calmodulin-dependent protein kinase. Requirement of tyrosine kinase activation for the anti-Ig-mediated Zp activation was also demonstrated through the use of the tyrosine kinase inhibitor herbimycin. These cellular gene regulatory molecules induced with anti-Ig may cooperatively play an important part in achieving efficient EBV activation as seen with anti-Ig treatment in B cells.
爱泼斯坦-巴尔病毒（EBV）裂解周期的启动依赖于BZLF1基因的转录。即使在没有其他病毒基因的情况下，B细胞表面免疫球蛋白（Ig）与抗Ig抗体交联也能激活BZLF1基因启动子（Zp）。我们在Zp中鉴定出了几个抗Ig反应元件，它们最初被定义为十四烷酰佛波醇-13-乙酸酯（TPA）反应元件（ZI重复序列和ZII，一个类似AP-1的结构域）。由于抗Ig交联会导致蛋白激酶C（PKC）激活和细胞内钙水平升高，因此对Zp进行了对这些细胞因子反应的测试。用钙离子载体A23187处理可增加Zp活性。当钙离子载体与PKC激活剂TPA联合使用时，Zp的诱导作用协同增强。PKC抑制剂1-（5-异喹啉磺酰基）-2-甲基哌嗪可抑制Zp的抗Ig诱导性。钙调蛋白拮抗剂R24571和三氟拉嗪可阻断抗Ig对Zp的激活。这些发现表明，Zp直接响应PKC以及钙/钙调蛋白依赖性蛋白激酶活性的变化。通过使用酪氨酸激酶抑制剂赫曲霉素，也证明了酪氨酸激酶激活对抗Ig介导的Zp激活的必要性。这些由抗Ig诱导的细胞基因调节分子可能在实现高效的EBV激活中协同发挥重要作用，就像在B细胞中用抗Ig处理时所看到的那样。
