Reactivation of lytic replication from B cells latently infected with Epstein-Barr virus occurs with high S-phase cyclin-dependent kinase activity while inhibiting cellular DNA replication
Reactivation of lytic replication from B cells latently infected with Epstein-Barr virus occurs with high S-phase cyclin-dependent kinase activity while inhibiting cellular DNA replication
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DOI：
10.1128/jvi.77.2.851-861.2003
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发表时间：
2003-01-01
影响因子：
5.4
通讯作者：
Tsurumi, T
中科院分区：
文献类型：
--
作者：
Kudoh, A;Fujita, M;Tsurumi, T
疱疹病毒的生产性感染和复制通常发生在生长停滞的细胞中，但在EB病毒（EBV）的情况下没有直接的证据，因为不存在没有外部刺激的有效裂解复制系统。然而，已知在EBV阴性上皮肿瘤细胞系中表达EBV裂解开关反式激活因子BZLF 1蛋白，通过诱导肿瘤抑制蛋白p53和细胞周期蛋白依赖性激酶（CDK）抑制剂p21（WAF-1/CIP-1）和p27（KIP-1），随后Rb蛋白低磷酸化形式的积累，将细胞周期阻滞在G（0）/G（1）。为了确定裂解性病毒复制的开始对潜伏性EBV感染的B LCL中的细胞事件的影响，在B 95 -8细胞中建立了通过诱导型BZLF 1蛋白表达的EBV裂解性复制程序的严格控制的诱导系统。裂解复制的诱导完全阻止了细胞周期进程和细胞DNA复制。令人惊讶的是，p53、p21（WAF-1/CIP-1）和p27 KIP（-1）的水平在诱导裂解程序之前和之后是恒定的，表明由裂解程序诱导的细胞周期停滞不是通过p53和CDK抑制剂介导的。此外，尽管细胞DNA复制被阻断，但观察到细胞周期蛋白E/A表达升高和Rb蛋白过度磷酸化形式的积累，这是细胞的后G（1）/S期特征。因此，虽然EBV裂解程序促进了参与从G（1）期到S期进展的特定细胞周期相关活动，但它抑制了细胞DNA合成。这样的细胞条件似乎特别有利于病毒裂解复制。
Productive infection and replication of herpesviruses usually occurs in growth-arrested cells, but there has been no direct evidence in the case of Epstein-Barr virus (EBV), since an efficient lytic replication system without external stimuli does not exist for the virus. Expression of the EBV lytic-switch transactivator BZLF1 protein in EBV-negative epithelial tumor cell lines, however, is known to arrest the cell cycle in G(0)/G(1) by induction of the tumor suppressor protein p53 and the cyclin-dependent kinase (CDK) inhibitors p21(WAF-1/CIP-1) and p27(KIP-1), followed by the accumulation of a hypophosphorylated form of the Rb protein. In order to determine the effect of the onset of lytic viral replication on cellular events in latently EBV-infected B LCLs, a tightly controlled induction system of the EBV lytic-replication program by inducible BZLF1 protein expression was established in B95-8 cells. The induction of lytic replication completely arrested cell cycle progression and cellular DNA replication. Surprisingly, the levels of p53, p21(WAF-1/CIP-1), and p27KIP(-1) were constant before and after induction of the lytic program, indicating that the cell cycle arrest induced by the lytic program is not mediated through p53 and the CDK inhibitors. Furthermore, although cellular DNA replication was blocked, elevation of cyclin E/A expression and accumulation of hyperphosphorylated forms of Rb protein were observed, a post-G(1)/S phase characteristic of cells. Thus, while the EBV lytic program promoted specific cell cycle-associated activities involved in the progression from G(1) to S phase, it inhibited cellular DNA synthesis. Such cellular conditions appear to especially favor viral lytic replication.