Stress granules in virus infections

应激颗粒(SG)是由停滞的信使核糖核酸、翻译因子组成的无膜性、相分离的复合体。 以及在细胞质中瞬时形成的RNA结合蛋白，以响应不同的胁迫信号， 包括病毒感染。在病毒感染过程中形成的SG，抗病毒应激颗粒(AvSG)，与 典型的SG因为它们招募抗病毒蛋白和信号通路的组件来发挥作用 安装有效的抗病毒反应的平台。然而，它的组成、时间变化和功能 病毒感染期间的avSG仍然知之甚少。SG的动态性质表明宿主细胞使用 AvSG作为抗病毒防御的信号中枢。另一方面，病毒已经进化出一种机制来 拮抗SG的形成和调整SG的用途以促进复制突出了在病毒中的重要作用 发病机制。SG的组成、组装和动力学方面的压力特定差异如何影响 病毒感染的结果仍然不清楚，这是我们对 信号事件和宿主与病毒的相互作用。我们最近的工作突出了avSG作为平台的作用 通过dsRNA病原体相关分子模式激活模式识别受体(PRR) 病毒感染期间的PAMPS和随后的干扰素(干扰素)反应。病毒过程中产生的dsRNA 感染作为PAMP通过结合胞浆Rig样解旋酶来刺激干扰素(IFN)的产生 (RLHs)、内体Toll样受体(TLRs)、dsRNA依赖的蛋白激酶(PKR)或2‘-5’寡腺苷 合成酶(OAS)。此外，病毒感染导致病毒和细胞RNA的降解，其作用机制是 干扰素诱导的核糖核酸酶，核糖核酸酶。我们最近发现核糖核酸酶L的双链RNA产物。 PAMP激活蛋白激酶受体，磷酸化真核细胞翻译起始因子-2(eIF2) 抑制翻译并诱导avSG的形成。我们的结果表明，avSG组件提供了 为RNA配体与PRRs的有效相互作用提供平台，以增强干扰素的产生和抗病毒效果。 我们对这一提议的总体假设是avSG的组成、组装和拆卸 在病毒感染期间发生变化，以允许宿主细胞做出反应，并通过限制损害来清除感染。在……里面 我们的初步研究表明，核糖核酸酶L的激活诱导了以SG蛋白G3BP1为标记的avSG的形成 含有抗病毒蛋白RIG-I、PKR、OAS和RNaseL。 以及将在本提案中使用的avSG中的蛋白质-蛋白质相互作用的生化表征。我们会 用以下具体目标测试我们的中心假设。目标1：确定应激特异性差异 在规范SG和avSG中的SG组成，目标2：确定动态变化在 病毒感染中的avSG组成。完成这些目标将使我们能够在以下方面取得进展 纯化avSG，通过遵循组装和拆解的动力学来剖析SG的抗病毒作用 分析avSG的组成，以提供应激反应途径和固有信号之间的关联。

Stress granules (SG) are non-membranous, phase-separated complexes of stalled mRNA, translation factors and RNA binding proteins that are formed transiently in the cytoplasm in response to diverse stress signals, including viral infections. SG formed during viral infection, antiviral stress granules (avSG), are distinct from canonical SG in that they recruit antiviral proteins and components of signaling pathways to function as a platform to mount an effective antiviral response. However, the composition, temporal changes and function of avSG during viral infections are still poorly understood. The dynamic nature of SG suggest that host cells use avSG as a signaling hub for antiviral defense. On the other hand, viruses have evolved mechanisms to antagonize SG formation and repurpose SG to facilitate replication highlighting an important role in viral pathogenesis. How the stress-specific differences in SG composition, assembly and dynamics impact the outcome of viral infections remains unclear and represents a critical gap in our understanding of signaling events and host-virus interactions. Our recent work has highlighted a role for avSG as a platform for the activation of pattern recognition receptors (PRRs) by dsRNA pathogen associated molecular patterns (PAMPs) and subsequent interferon (IFN) response during viral infections. DsRNAs produced during viral infections serve as PAMPs to stimulate interferon (IFN) production by binding the cytosolic Rig-like helicases (RLHs), endosomal Toll-like receptors (TLRs), dsRNA-dependent protein kinase (PKR) or 2’-5’oligoadenylate synthetase (OAS). Furthermore, virus infection induces degradation of viral and cellular RNAs by the activity of interferon-induced endoribonuclease, RNase L. We have recently shown that dsRNA products of RNase L activity function as PAMPs and activate PKR, phosphorylate eukaryotic translation initiation factor-2 (eIF2) to suppress translation and induce avSG formation. Our results demonstrate that avSG assembly provides a platform for efficient interaction of RNA ligands with PRRs to enhance interferon production and antiviral effect. Our overarching hypothesis for this proposal is that composition, assembly and disassembly of avSG change during viral infection to allow host cells to respond and clear infection by limiting damage. In preliminary studies we show that activation of RNase L induces avSG formation marked by SG protein, G3BP1 and contain antiviral proteins Rig-I, PKR, OAS and RNase L. We developed a novel method to purify avSG and biochemically characterized protein-protein interactions in avSG that will be used in this proposal. We will test our central hypothesis with the following specific aims. Aim 1: To determine stress-specific differences in SG composition in canonical SG and avSG, Aim 2: To determine the physiological role of dynamic change in avSG composition in virus infections. Completion of these aims will allow us to build on the advances in purifying avSG to dissect the antiviral role of SG by following the dynamics of assembly or disassembly and analyzing the avSG composition to provide correlation of stress response pathways and innate signaling.