Translation Regulation by Enterovirus Proteinase

这项研究的长期目标是了解肠道病毒， 脊髓灰质炎病毒（PV）和柯萨奇病毒（CVB 3）在刺激细胞增殖的同时， 病毒mRNA在感染细胞中的高效翻译。我们和其他人已经表明，分裂的 翻译起始因子eIF 4G将阻断新的加帽mRNA在核糖体上的组装， 的PABP需要与e！F4 G会导致严重的翻译抑制。PABP裂解影响晚期 翻译中的步骤目前还不确定，然而切割可能通过5 '- 3'端相互作用。核糖体再循环的机制及其生化要求是 未知此外，肠道病毒和可能大多数其他正链RNA病毒必须突然关闭 在病毒RNA合成开始之前，感染病毒基因组的向下翻译。我们假设 PABP裂解也是抑制病毒翻译所必需的，沿着关键IRES的裂解 反式激活因子 涉及eIF 4 E、eIF 4G和PABP的翻译调节机制现在被认为与eIF 4 E、eIF 4G和PABP相互作用。 在几个水平上的mRNA衰变机制。此外，与靶向的RNA的3' UTR结合的microRNA， 细胞内的mRNAs也通过未知的机制沉默翻译，以某种方式导致mRNAs的转运 从多聚核糖体到称为P体和应激颗粒的其他细胞区室。我们发现 G3 BP是一个重要的应激颗粒形成的核因子，在PV感染的细胞中被3C切割 蛋白酶因此，病毒正在一个新的水平上攻击整个翻译调节装置。 该建议的目的将确定PABP切割在从病毒翻译到转录的转换中的作用。 RNA复制，将确定核糖体再循环在这一开关中的作用，并将研究其功能。 G3 BP切割的病毒复制周期和microRNA翻译沉默。 这些结果将提供新的基本信息，细胞如何调节基因表达， 翻译水平。我们将更多地了解翻译起始因素之间的密切相互作用， mRNA沉默/衰变途径。我们将阐明为什么RNA病毒需要控制mRNA的流动， 多聚核糖体对应激颗粒的影响。这一新的信息将是有用的，在广泛的领域的研究， 基因表达的调节，miRNA介导的翻译沉默，以及细胞应激反应， 癌症和细胞凋亡。

The long term goal of this research is to understand the mechanism by which enteroviruses such as poliovirus (PV) and Coxsackievirus (CVB3) inactivate translation of nearly all cellular mRNA while stimulating efficient translation of viral mRNA in infected cells. We and others have shown that cleavage of the translation initiation factor elF4G will block assembly of new capped mRNA on ribosomes, and that cleavage of PABP is required in concert with e!F4G to cause drastic translation inhibition. PABP cleavage affects late steps in translation that are presently undefined, however cleavage likely interupts ribosome recycling via 5'- 3' interactions on mRNA. The mechanism of ribosome recycling and its biochemical requirements are unknown. In addition, enteroviruses and probably most other plus strand RNA viruses must abruptly shut down translation of the infecting viral genome before viral RNA synthesis can begin. We hypothesize that PABP cleavage is also required for inhibition of viral translation along with cleavage of key IRES transactivating factors. Translation regulation mechanisms involving elF4E, elF4G and PABP are now thought to interface with mRNA decay mechanisms on several levels. In addition, microRNAs, which bind to 3' UTR of targeted cellular mRNAs, also silence translation by unknown mechanisms that somehow result in transit of mRNAs from polysomes to other cell compartments called P-bodies and stress granules. We have discovered that G3BP, a key factor that nucleates formation of stress granules, is cleaved in PV-infected cells by 3C protease. Thus, the virus is attacking the overall translation regulatory apparatus at a new level. The aims in this proposal will determine the role of PABP cleavage in the switch from viral translation to RNA replication, will determine the role of ribosome recycling in this switch, and will investigate the function of G3BP cleavage on the viral replication cycle and microRNA-translation silencing. These results will provide new fundamental information how cells regulate gene expression at the translation level. We will learn more about the close interplay between translation initiation factors and mRNA silencing/decay pathways. We will elucidate why RNA viruses need to control the flow of mRNA from polysomes to stress granules. This new information will be useful in the broad areas of studies of viral regulation of gene expression, miRNA-mediated translation silencing, and cellular stress responses in cancer and apoptosis.