Rhinovirus-Induced Shutoff of Cellular Responses

RNA小核糖核酸病毒已经进化出非常强大和有效的机制来表达它们的功能。 蛋白质和推翻宿主防御。新的内部核糖体进入位点（IRES）允许这些基因组 绕过5'帽结构的正常翻译要求，并有效地将核糖体引诱到病毒中， 而不是细胞通路。捕获的核糖体向下传递单个长的开放阅读框（ORF）， 产生的多聚蛋白实际上是所有结构和酶单位的串联连接， 快速和致命的感染。单个蛋白质片段在协同和后协同释放 在一个精心设计的蛋白水解级联中，这是这个家族的一个定义特征。分子 小核糖核酸病毒，特别是脊髓灰质炎病毒和密切相关的人鼻病毒的生物学， 也许是生物学中最容易理解和最容易接近的实验系统之一。 IRES翻译、蛋白质加工或基因组复制的基本机制已经被研究。 研究了几十年，有极好的分子和重组工具可用于研究 病毒生命周期的各个方面该项目的重点是人类鼻病毒如何 煽动性地破坏细胞的先天免疫陷阱，削弱该细胞触发警报的能力， 从而改变警报本身的性质。第一个感染细胞的分子战场， 蛋白酶，2Apro和3Cpro，通过进化策略性地磨练用于此特定目的的酶， 根据细胞类型、细胞周期、宿主遗传学、免疫史， 和当前的医学倾向我们认为，可以通过基因突变来改变疾病表型， 由这些蛋白酶的能力或不能关闭关键的细胞转录的能力在它们的核心触发 和翻译过程。随后的每一次免疫和疾病反应都是由此产生的 结果。在最终的分子水平上，这些蛋白酶的活性引发了一系列事件 引发或阻止疾病发作。这个项目的实验将检查卵裂 鼻病毒感染使细胞质-核失活的过程和分子结果 这会导致细胞转运，从而削弱细胞进行mRNA转录或帽依赖性翻译的能力。 他们将决定是否有必要无条件地关闭病毒引起的核运输， 病毒复制和细胞裂解。或者，在这些过程仅部分有效的条件下， 宿主诱导的先天触发因子的上调然后迅速升级为全面的免疫反应， 可能不适合实际感染的范围和严重程度。该项目还将审查 宿主关闭活性在多种人类细胞类型中是普遍存在的和相似的，或者由细胞因子调节。 培养物的遗传学和/或先天免疫状态以及病毒的基因型。

The RNA picornaviruses have evolved wonderfully robust and effective mechanisms to express their proteins and override host defenses. Novel internal ribosomal entry sites (IRESs) allow these genomes to bypass normal translational requirements for 5' cap structures and efficiently lure the ribosomes into viral instead of cellular pathways. The captured ribosomes pass down a single, long open reading frame (ORF), creating polyproteins that are in reality, tandem linkages of all structural and enzymatic units necessary for rapid and virulent infection. Individual protein fragments are liberated co-translationally and posttranslationally in an elaborate proteolytic cascade that is a defining feature of this family. The molecular biology of picornaviruses, and in particular that of poliovirus and the closely related human rhinovirus, is perhaps one of the best understood and most thoroughly accessible experimental systems in all of biology. Basic mechanisms of IRES translation, protein processing or genome replication have been under investigation for decades and there are superb molecular and recombinant tools available for the study of every aspect of the virus lifecycle. The focus of this project is the way in which the human rhinoviruses can seditiously subvert a cell's innate immunity traps, crippling the capacity of that cell to trigger an alarm or altering the nature of the alarm itself. The molecular battleground in that first infected cell, pits two key viral proteases, 2Apro and 3Cpro, enzymes strategically honed by evolution for this particular purpose, against cellular defenses that may vary significantly according to cell-type, cell-cycle, host genetics, immune history and current medical predisposition. We propose that substantially different disease phenotypes can be triggered at their core, by the ability or inability of these proteases to shutoff of crucial cellular transcription and translational processes. Every subsequent immune and disease response is consequent to this outcome. At the ultimate molecular level, the activities of these proteases instigate the cascade of events that set off or prevent an episode of disease. The experiments in this project will examine the cleavage processes and molecular consequences by which rhinovirus infection inactivates cytoplasmic-nuclear transport, thus crippling the ability of the cell to carry out mRNA transcription, or cap-dependent translation. They will determine whether an unconditional viral-induced shutoff of nuclear transport is necessary to allow viral replication and cell lysis. Or, under conditions when these processes are only partially effective, whether a host-induced up-regulation of innate triggers then quickly escalates into a full-blown immune response, that may or may not be inappropriate for the extent and severity of actual infection. The project will also examine host shutoff activities are ubiquitous and similar in multiple human cell types, or are modulated by the genetics and/or innate immunity status of the cultures and the genotype of virus.