Department of Molecular Sciences, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
J Biol Chem. 2010 Feb 26;285(9):6080-90. doi: 10.1074/jbc.M109.054486. Epub 2010 Jan 4.
The zinc finger antiviral protein (ZAP) is an interferon-stimulated gene that restricts the replication of retroviruses, alphaviruses, and filoviruses. Relatively little is known, however, regarding the detailed mechanism of ZAP induction during viral infections. We show that, although being inducible by either interferon or virus, expression of ZAP is more efficiently activated by virus than are several other classical interferon-stimulated genes and that viral induction of ZAP occurs under the direct control of interferon regulatory factor 3 (IRF3) independent of interferon paracrine/autocrine signaling. ZAP was up-regulated in cells unresponsive to type I and III interferons upon engagement of TLR3, retinoic inducible gene I/melanoma differentiation-associated gene 5 pathways, or ectopic expression of a constitutively active IRF3 mutant. Conversely, induction of ZAP by virus or dsRNA was severely impaired in cells expressing a dominant-negative mutant IRF3 and completely abrogated in cells lacking IRF3. In contrast to IRF3, ZAP induction was independent of NF-kappaB activity. Mutational analysis of the human ZAP promoter revealed that multiple interferon-stimulated response elements far distal to the transcription start site serve redundantly to control IRF3-dependent induction of ZAP transcription. Chromatin immunoprecipitation assays demonstrated that IRF3 selectively binds the distal interferon-stimulated response elements in human ZAP promoter following viral infection. Collectively, these data suggest that ZAP is a direct target gene of IRF3 action in cellular antiviral responses.
锌指抗病毒蛋白（ZAP）是一种干扰素刺激基因，可限制逆转录病毒、甲病毒和丝状病毒的复制。然而，关于病毒感染过程中 ZAP 诱导的详细机制，人们知之甚少。我们发现，尽管 ZAP 可被干扰素或病毒诱导，但与其他几种经典的干扰素刺激基因相比，ZAP 的表达被病毒更有效地激活，并且 ZAP 的病毒诱导是在干扰素调节因子 3（IRF3）的直接控制下发生的，与干扰素旁分泌/自分泌信号无关。在 TLR3、视黄酸诱导基因 I/黑色素瘤分化相关基因 5 途径或组成型激活的 IRF3 突变体的异位表达作用下，未对 I 型和 III 型干扰素产生反应的细胞中，ZAP 的表达上调。相反，在表达显性负突变体 IRF3 的细胞中，病毒或 dsRNA 诱导 ZAP 的能力严重受损，在缺乏 IRF3 的细胞中完全消除。与 IRF3 不同，ZAP 的诱导不依赖于 NF-κB 活性。对人 ZAP 启动子的突变分析表明，转录起始位点远侧的多个干扰素刺激反应元件冗余地控制 ZAP 转录的 IRF3 依赖性诱导。染色质免疫沉淀分析表明，病毒感染后，IRF3 选择性地结合人 ZAP 启动子中的远端干扰素刺激反应元件。总的来说，这些数据表明 ZAP 是细胞抗病毒反应中 IRF3 作用的直接靶基因。
