Mechanism and Function of ISG15

ISG15的机制和功能

• 批准号: 9176962
• 负责人: JON HUIBREGTSE
• 金额: $ 38.41万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9176962
• 关键词: Address; Affect; Attenuated; BCG Vaccine; Biochemical; Biochemistry; Capsid Proteins; Cell Surface Receptors; Cells; Child; DNA Viruses; Disease; Dominant-Negative Mutation; Ebola virus; Enzymes; Event; Extracellular Protein; HIV; Herpesviridae; Human; Human Herpesvirus 8; Human Papillomavirus; Immune response; Individual; Infection; Influenza; Interferon Type II; Interferon-alpha; Interferons; Interleukin-12; Investigation; Kaposi Sarcoma; Life; Ligase; Mediating; Modification; Molecular; Mutation; Mycobacterium Infections; Mycobacterium bovis; Natural Immunity; Natural Killer Cells; Paper; Pathway interactions; Patients; Peripheral Blood Mononuclear Cell; Population; Predisposition; Principal Investigator; Production; Proteins; RNA Viruses; Reporting; Retroviridae; Ribosomes; Role; Signal Transduction; Specificity; Stream; Structural Genes; Structure; System; Testing; Therapeutic; Translating; Ubiquitin; Ubiquitin Like Proteins; Viral; Viral Physiology; Viral Proteins; Virion; Virus; Virus Diseases; Virus Inhibitors; abstracting; antimicrobial; base; cytokine; effective therapy; extracellular; follow-up; gene product; improved; influenzavirus; insight; interferon therapy; microbial; microbial disease; mycobacterial; polypeptide; programs; protein function; receptor; response; stable cell line; synergism; tool; ubiquitin ligase; viral RNA; viral interferon regulatory factor-1

Project Summary/Abstract The Type 1-interferon (IFN-α/β) response is the first line of defense against viral infections. Hundreds of proteins, referred to as ISGs (Interferon-Stimulate Gene products) are synthesized in response to IFN-α or β stimulation, and these proteins mediate an extremely broad spectrum of anti- viral effects. ISG15 was one of the first ISGs to be identified and the first ubiquitin-like modifier (Ubl) to be discovered, however it is only recently that we begin to have an understanding of the remarkable biochemical functions of this protein. ISG15 has anti-viral activity against a wide range of human viruses, including Influenza, Herpesviruses, Retroviruses, Sindbis, and Ebola. ISG15 is conjugated to hundreds of cellular proteins in IFN-stimulated cells, and a single IFN-induced ligase, Herc5, mediates conjugation to these target proteins. Herc5 is ribosome-associated and “ISGylates” newly synthesized protiens in a co-translational manner, with little or no target protein specificity. We hypothesize that in the context of an interferon response, newly translated viral proteins, rather than cellular proteins, are the primary targets of this system, and that ISG15 acts by sterically interfering with the function of viral proteins, particularly those that form oligomeric structures (such as capsid proteins). Surprisingly, ISG15 has a second function as an extracellular protein that stimulates the production of Type 2 Interferon, IFN-γ. While this function was reported over two decades ago, there was little follow-up to the original studies. This function returned to the fore with the recent discovery of ISG15-deficient patients who were highly susceptible to mycobacterial infection as a result of being unable to mount an effect IFN-γ response. Further characterization of this activity has shown that ISG15 is highly synergistic with IL-12 in stimulating production of IFN-γ by Natural Killer (NK) cells. This project will address critical biochemical questions in both of the ISG15 functions described above – the intracellular conjugation of ISG15, and the extracellular IFN-γ signaling by ISG15. In the first aim we will characterize the factors that localize Herc5 to the ribosome, identify the determinants that confer ISG15 ligase activity to Herc5, and gain insights into Herc5 activities through characterization of an unusual viral inhibitor of ISGylation. In the second aim we will characterize the determinants within the ISG15 protein required for IFN-γ signaling, identify the putative cell surface receptor for ISG15 receptor, and characterize the down-stream ISG15 signaling events. We anticipate that these biochemical studies will provide important insights into the innate immune response to both human viral and microbial infections.

项目摘要/摘要 1型干扰素(干扰素-α/β)反应是抵御病毒感染的第一道防线。 数以百计的蛋白质，被称为ISGs(干扰素刺激基因产物)在 对干扰素-α或β刺激的反应，这些蛋白介导了非常广泛的抗- 病毒效应。ISG15是最早被发现的ISG之一，也是第一个泛素样修饰物(UbL) 被发现，然而，直到最近我们才开始了解 这种蛋白质的生化功能。 ISG15对多种人类病毒具有抗病毒活性，包括流感， 疱疹病毒、逆转录病毒、辛德比斯病毒和埃博拉病毒。ISG15与数百种细胞蛋白偶联 在干扰素刺激的细胞中，单个干扰素诱导的连接酶Herc5介导与这些靶点的结合 蛋白质。Herc5是核糖体相关的和“ISGylates”新合成的蛋白在共翻译 方式，几乎或没有目标蛋白的特异性。我们假设在干扰素的情况下 新翻译的病毒蛋白，而不是细胞蛋白，是这种反应的主要目标 ISG15通过立体干扰病毒蛋白的功能发挥作用，尤其是那些 形成寡聚体结构(如衣壳蛋白)。 令人惊讶的是，ISG15还有第二个功能，即作为细胞外蛋白刺激 2型干扰素-γ的生产虽然这一功能在20多年前就有报道，但有 对最初的研究几乎没有后续行动。该函数随着最近发现的 ISG15缺陷患者，因以下原因极易感染分枝杆菌感染 无法装载有效的干扰素-γ反应。对这一活动的进一步描述表明， 在刺激自然杀伤细胞(NK)产生干扰素-γ方面，ISG15与IL-12具有高度的协同作用。 该项目将解决所描述的ISG15功能中的关键生化问题 上图为ISG15的胞内结合和胞外干扰素-γ信号转导。在 首先，我们将确定将Herc5定位于核糖体的因素，确定决定因素 这将ISG15连接酶活性授予Herc5，并通过 一种不寻常的ISG化病毒抑制因子的特征。在第二个目标中，我们将描述 干扰素-γ信号转导所需的ISG15蛋白中的决定因素，识别可能的细胞表面 ISG15受体，并鉴定下游的ISG15信号事件。我们期待着 这些生化研究将提供对这两种疾病的先天免疫反应的重要见解 人类病毒和微生物感染。