The Induction of Interferon Regulatory Factor 7 Sumoylation by EBV LMP1

EBV LMP1 诱导干扰素调节因子 7 苏酰化

• 批准号: 7908237
• 负责人: Gretchen L Bentz
• 金额: $ 5.22万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-24 至 2011-09-23
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7908237
• 关键词: Affect; Arginine; C-terminal; Cell Nucleus; Enzymes; Epstein-Barr Virus latency; Human Herpesvirus 4; Immune response; Interferon Type I; LMP1; Lysine; Membrane Proteins; Modification; Mutate; Oncogene Proteins; Phosphorylation; Post-Translational Protein Processing; Proteins; Public Health; Regulation; Reporting; Role; Signal Transduction; Testing; Treatment-Related Cancer; Tumor Necrosis Factor Receptor; Ubiquitin Like Proteins; Ubiquitination; Viral; Viral Proteins; Virus; Work; cancer therapy; cancer type; insight; interferon regulatory factor-7; mutant; public health relevance; transcription factor; tumor

DESCRIPTION (provided by applicant): Epstein-Barr virus (EBV) is a tumor causing virus that is associated with several types of cancer, and the main EBV oncoprotein is latent membrane protein (LMP) 1, a constitutively active membrane protein that mimics the signaling induced by the tumor necrosis factor receptor family. We have reported that LMP1 induces the expression of interferon regulatory factor (IRF)-7, a transcription factor that is a key regulator of Type I interferons in innate immune responses. LMP1 regulates the transcriptional activity of IRF7 via post-translational modifications, including phosphorylation and ubiquitination. Therefore, we investigated if LMP1 induces other modifications of IRF7, specifically that by the small ubiquitin-like protein modifier (SUMO)-1, in order to regulates its function. We found that LMP1 interacts with Ubc9, the only reported SUMO-conjugating enzyme, possibly via the understudied C-terminal activating region (CTAR3). LMP1 also induced the interaction of Ubc9 with IRF7 leading to the sumoylation of IRF7, which resulted in decreased IRF7 turnover. Sumoylated IRF7 accumulated in the nucleus where its transcriptional activity is modestly increased. Therefore, we hypothesize that the induction of the sumoylation of IRF7 by LMP1 moderates the activation of the immune response, and we propose two aims to test this hypothesis. First, we will determine the requirements for IRF7 sumoylation. Several IRF7 deletion and point mutants, where lysines are mutated to arginines, will be examined to determine which lysine residue(s) is/are sumoylated. In addition, a LMP1 CTAR3 deletion mutant will be examined for its ability to sumoylate IRF7. Finally, we will examine the role IRF7 sumoylation has on the induction of innate immune responses. The results will provide insight into how IRF7 is sumoylated and implicate a new function for understudied LMP1 CTAR3. Second, we will investigate competition between sumoylation and ubiquitination of IRF7. Each post- translational modification can alter IRF7 function in a distinct manner, so we will investigate the role sumoylation has on IRF7 ubiquitination, and vice-versa. The effect these modifications have on IRF7 transcriptional activity will also be examined to decipher how the different modifications alter IRF7's function as a central transcription factor for innate immune responses. Relevance to public health: Regulating protein sumoylation is a new target for anti-cancer therapies. This work will further our understanding of protein sumoylation during EBV latency, by defining a new role for LMP1 CTAR3 and deciphering how sumoylation affected the function of IRF7. Together, this project will provide insight into new role for LMP1 and IRF7 during EBV latency as well as potential targets for the regulation of anti-viral immune responses.

描述（由申请人提供）：EB病毒（EBV）是一种与几种类型的癌症相关的致瘤病毒，主要的EBV癌蛋白是潜伏膜蛋白（LMP）1，一种组成型活性膜蛋白，模拟肿瘤坏死因子受体家族诱导的信号传导。我们已经报道了LMP 1诱导干扰素调节因子（IRF）-7的表达，IRF-7是一种转录因子，是先天免疫应答中I型干扰素的关键调节因子。LMP 1通过翻译后修饰（包括磷酸化和泛素化）调节IRF 7的转录活性。因此，我们研究了LMP 1是否诱导IRF 7的其他修饰，特别是通过小泛素样蛋白修饰物（SUMO）-1，以调节其功能。我们发现LMP 1与Ubc 9相互作用，Ubc 9是唯一报道的SUMO结合酶，可能是通过研究不足的C-末端激活区（CTAR 3）。LMP 1还诱导Ubc 9与IRF 7的相互作用，导致IRF 7的SUMO化，这导致IRF 7周转减少。类小泛素化的IRF 7在细胞核中积累，在那里其转录活性适度增加。因此，我们假设LMP 1诱导IRF 7的SUMO化可以调节免疫反应的激活，并且我们提出了两个目的来验证这一假设。 首先，我们将确定IRF 7类泛素化的要求。将检查几种IRF 7缺失和点突变体，其中赖氨酸突变为丝氨酸，以确定哪些赖氨酸残基被苏莫酰化。此外，将检查LMP 1 CTAR 3缺失突变体使IRF 7类小泛素化的能力。最后，我们将研究IRF 7类小泛素化在诱导先天免疫应答中的作用。这些结果将提供对IRF 7如何被sumoylated的深入了解，并暗示了未充分研究的LMP 1 CTAR 3的新功能。 其次，我们将研究IRF 7的sumoylation和泛素化之间的竞争。每个翻译后修饰可以以不同的方式改变IRF 7功能，因此我们将研究类小泛素化对IRF 7泛素化的作用，反之亦然。这些修饰对IRF 7转录活性的影响也将被检查，以破译不同的修饰如何改变IRF 7作为先天免疫应答的中心转录因子的功能。 与公共卫生的相关性：调节蛋白质类小泛素化是抗癌治疗的新靶点。这项工作将通过定义LMP 1 CTAR 3的新作用和破译sumoylation如何影响IRF 7的功能，进一步了解EBV潜伏期期间蛋白质的sumoylation。总之，该项目将为LMP 1和IRF 7在EBV潜伏期的新作用以及调节抗病毒免疫反应的潜在靶点提供深入了解。