Irurzun A, Sánchez-Palomino S, Novoa I, Carrasco L
Centro de Biología Molecular, Universidad Autónoma de Madrid-CSIC, Spain.
J Virol. 1995 Dec;69(12):7453-60. doi: 10.1128/JVI.69.12.7453-7460.1995.
Addition of monensin or nigericin after poliovirus entry into HeLa cells prevents the inhibition of host protein synthesis by poliovirus. The infected cells continue to synthesize cellular proteins at control levels for at least 8 h after infection in the presence of the ionophore. Cleavage of p220 (gamma subunit of eukaryotic initiation factor 4 [eIF-4 gamma]), a component of the translation initiation factor eIF-4F, occurs to the same extent in poliovirus-infected cells whether or not they are treated with monensin. Two hours after infection there is no detectable intact p220, but the cells continue to translate cellular mRNAs for several hours at levels similar to those in uninfected cells. Nigericin or monensin prevented the arrest of host translation at all the multiplicities of poliovirus infection tested. At high multiplicities of infection, an unprecedented situation was found: cells synthesized poliovirus and cellular proteins simultaneously. Superinfection of vesicular stomatitis virus-infected HeLa cells with poliovirus led to a profound inhibition of vesicular stomatitis virus protein synthesis, while nigericin partially prevented this blockade. Drastic inhibition of translation also took place in influenza virus-infected Vero cells treated with nigericin and infected with poliovirus. These findings suggest that the translation of newly synthesized mRNAs is dependent on the integrity of p220, while ongoing cellular protein synthesis does not require an intact p220. The target of ionophore action during the poliovirus life cycle was also investigated. Addition of nigericin at any time postinfection profoundly blocked the synthesis of virus RNA, whereas viral protein synthesis was not affected if nigericin was added at 4 h postinfection. These results agree well with previous findings indicating that inhibitors of phospholipid synthesis or vesicular traffic interfere with poliovirus genome replication. Therefore, the action of nigericin on the vesicular system may affect poliovirus RNA synthesis. In conclusion, monensin and nigericin are potent inhibitors of poliovirus genome replication that prevent the shutoff of host translation by poliovirus while still permitting cleavage of p220.
脊髓灰质炎病毒进入HeLa细胞后添加莫能菌素或尼日利亚菌素可防止脊髓灰质炎病毒对宿主蛋白质合成的抑制。在离子载体存在的情况下，感染后的细胞在至少8小时内以对照水平继续合成细胞蛋白质。翻译起始因子eIF-4F的一个组分p220（真核起始因子4的γ亚基）的切割，在脊髓灰质炎病毒感染的细胞中，无论是否用莫能菌素处理，其发生程度相同。感染后两小时，未检测到完整的p220，但细胞继续以与未感染细胞相似的水平翻译细胞mRNA数小时。尼日利亚菌素或莫能菌素在所有测试的脊髓灰质炎病毒感染复数下均能防止宿主翻译的停滞。在高感染复数时，发现了一种前所未有的情况：细胞同时合成脊髓灰质炎病毒和细胞蛋白质。用脊髓灰质炎病毒对水泡性口炎病毒感染的HeLa细胞进行超感染导致水泡性口炎病毒蛋白质合成受到严重抑制，而尼日利亚菌素可部分防止这种阻断。在用尼日利亚菌素处理并感染脊髓灰质炎病毒的流感病毒感染的Vero细胞中也发生了对翻译的剧烈抑制。这些发现表明，新合成mRNA的翻译依赖于p220的完整性，而正在进行的细胞蛋白质合成不需要完整的p220。还研究了脊髓灰质炎病毒生命周期中离子载体作用的靶点。感染后任何时间添加尼日利亚菌素都会严重阻断病毒RNA的合成，而如果在感染后4小时添加尼日利亚菌素，则病毒蛋白质合成不受影响。这些结果与先前的发现非常吻合，即磷脂合成或囊泡运输抑制剂会干扰脊髓灰质炎病毒基因组复制。因此，尼日利亚菌素对囊泡系统的作用可能会影响脊髓灰质炎病毒RNA的合成。总之，莫能菌素和尼日利亚菌素是脊髓灰质炎病毒基因组复制的有效抑制剂，它们可防止脊髓灰质炎病毒关闭宿主翻译，同时仍允许p220的切割。
