Translation Regulation by Enterovirus Proteinase

描述（由申请人提供）：本研究的长期目标是了解肠道病毒（如脊髓灰质炎病毒（PV）和柯萨奇病毒（CVB 3））控制感染细胞中细胞和病毒翻译的机制，进而了解如何正常调节翻译和基因表达。翻译调控机制现在包括翻译沉默（例如microRNA），并延伸到RNA颗粒的动态组装/拆卸，称为应激颗粒（SG）和P体（PB），其含有抑制沉默的mRNP。这些结构在应激期间协助细胞稳态，并作为mRNP的临时储存/分类位点，并且在PB的情况下，作为mRNA衰变的位点。我们已经发现，G3 BP，一个关键的因素，核形成的压力颗粒，被切割在PV感染的细胞由病毒3C蛋白酶，导致损失的SG在细胞中。实验提出辨别G3 BP与mRNP复合物中的起始因子的相互作用，调节翻译和G3 BP裂解如何废除这一功能。实验还将确定柯萨奇病毒用于阻断SG形成的替代机制和所需的最小病毒蛋白。我们还表明，G3 BP表达组装SG，诱导抗病毒状态，并阻止PV复制。第二个目标将阐明这种有效的抗病毒活性的机制，并发现它是否源于病毒所需的B因子的隔离，或者SG组装本身是否发出JNK信号或激活先天免疫的其他途径。我们新出现的证据表明，压力反应与先天免疫反应在几个层面上联系在一起，形成一个综合的压力/先天免疫反应。我们还确定了PV在细胞中分散PB，并在此过程中降解/切割mRNA衰变途径的三个关键组分，Xrn 1，Dcp 1a和Pan 3。我们将阐明PB分散的机制，并确定感染过程中这些因子的丢失是否能稳定病毒RNA。总的来说，拟议的研究是重要的，因为病毒攻击的翻译/mRNP调节装置在一个新的水平的RNA颗粒，这是知之甚少，但在维持细胞稳态和应力生存发挥关键作用。SG和PB可能可以强烈抑制病毒复制，这项研究的新见解可能会导致新的抗病毒策略。

DESCRIPTION (provided by applicant): The long term goal of this research is to understand the mechanism by which enteroviruses such as poliovirus (PV) and Coxsackievirus (CVB3) control cellular and viral translation in infected cells and in turn, discern how translation and gene expression are regulated normally. Translation regulation mechanisms now encompass translation silencing (e.g. microRNAs) and extend to dynamic assembly/disassembly of RNA granules, called stress granules (SG) and P-bodies (PB) that contain translationally-silenced mRNPs. These structures assist cell homeostasis during stress and serve as temporary storage/triage sites for mRNPs, and in the case of PBs, sites for mRNA decay. We have discovered that G3BP, a key factor that nucleates formation of stress granules, is cleaved in PV-infected cells by virus 3C protease, resulting in loss of SG in cells. Experiments are proposed to discern interactions of G3BP with initiation factors in mRNP complexes that regulate translation and how G3BP cleavage abrogates this function. Experiments will also define alternate mechanism(s) employed by Coxsackievirus to block SG formation and the minimal viral proteins required. We have also shown that G3BP expression assembles SGs that induce antiviral states, and block PV replication. The second aim will elucidate the mechanism of this potent antiviral activity and discover if it stems from sequestration of factors required b the virus or if SG assembly itself signals JNK or other pathways that activate innate immunity. Our emerging evidence suggests stress responses are linked to innate immune responses at several levels to form an integrated stress/innate immune response. We have also determined that PV disperses PB in cells and in the process, degrades/cleaves three critical components of the mRNA decay pathway, Xrn1, Dcp1a and Pan3. We will elucidate the mechanism of PB dispersal and determine if loss of these factors during infection stabilizes viral RNA. Overall, proposed studies are significant since the virus is attacking the translation/mRNP regulatory apparatus at a novel level of RNA granules, which are poorly understood but play key roles in maintaining cell homeostasis and stress survival. SG and perhaps PBs can strongly inhibit virus replication and new insights from this study may lead to novel antiviral strategies.