Molecular effects of SUMOylation on influenza virus infection: SUMO and NS1

描述（由申请人提供）：流感病毒仍然是对全球人类健康的主要威胁。高致病性禽流感毒株向人类直接传播的持续事件，H1N1人类毒株中对当前抗流感药物的耐药毒株的高流行率，以及猪源H1N1与高致病性H5N1禽流感毒株之间的高度遗传相容性，表明人类面临致命的耐药大流行毒株出现的可能性仍然很高。开发广谱抗流感疗法的一个可行的新策略是针对病毒所需的细胞成分。在我们之前的研究中，我们评估了细胞SUMOylation系统与流感感染的相关性。我们的数据确定了几种流感蛋白作为真正的SUMO靶点，揭示了病毒触发细胞SUMO化的两倍全球增长的能力，并证明了细胞SUMO化的大规模全球变化影响病毒蛋白表达和病毒增殖。因此，细胞SUMOylation系统似乎在流感病毒感染中起重要作用。重要的是，在所确定的所有病毒SUMO靶点中，非结构蛋白NS1是最有效的SUMO修饰。考虑到这一事实，NS1在病毒感染过程中发挥的众多作用，以及通常与SUMOylation相关的功能，我们假设SUMOylation通过影响NS1与其他病毒和细胞蛋白建立特异性蛋白-蛋白相互作用的能力来调节NS1的功能，从而解释其与流感感染的相关性。为了验证这一假设，我们将评估NS1 SUMOylation对两个主要参数的影响：i) NS1与其他病毒和细胞蛋白相互作用的能力。ii) NS1的主要功能和生化特征，即其中和i型干扰素反应的能力、细胞定位和半衰期。这些研究将使用蛋白质突变体、病毒突变体、稳定转导的细胞系和NS1 SUMOylation的人工调节剂的组合来进行。所产生的数据将为流感病毒感染过程中NS1功能的翻译后调控和SUMOylation介导的分子效应提供重要见解，并有可能为开发广谱抗流感疗法提供新的靶点。此外，这些研究也将扩大我们对病毒与细胞SUMOylation系统之间相互作用的理解。

DESCRIPTION (provided by applicant): Influenza virus continues to be a major threat to global human health. The persistent episodes of direct transmission of highly pathogenic avian influenza strains to humans, the high prevalence of resistant strains to current anti-influenza drugs among H1N1 human strains, and the high genetic compatibility between swine- origin H1N1 and highly pathogenic avian H5N1 strains, suggest that the odds of humanity facing the emergence of a deadly drug-resistant pandemic strain remain high. A plausible new strategy to develop broad- spectrum anti-influenza therapies is to target cellular components required by the virus. In our previous studies, we evaluated the relevance of the cellular SUMOylation system for influenza infection. Our data identified several influenza proteins as bona fide SUMO targets, revealed the ability of the virus to trigger a two-fold global increase in cellular SUMOylation, and demonstrated that large global changes in cellular SUMOylation affect viral protein expression and virus multiplication. Therefore, the cellular SUMOylation system appears to play an important role for influenza virus infections. Importantly, out of all viral SUMO targets identified, the non-structural protein NS1 was the most efficiently SUMOylated. Considering this fact, the numerous roles played by NS1 during viral infection, and the functions normally associated to SUMOylation, we hypothesize that SUMOylation regulates NS1 function by affecting its ability to establish specific protein-protein interactions with other viral and cellular proteins, thus explaining its relevance for influenza infection. To test this hypothesis, we will evaluate the effects exerted by NS1 SUMOylation on two main parameters: i) NS1's ability to interact with other viral and cellular proteins. ii) The main functional and biochemical characteristics of NS1, namely its ability to neutralize type-I interferon responses, its cellular localization, and its half-life. These studies will be pursued using a combination of protein mutants, viral mutants, stably transduced cell lines, and an artificial modulator of NS1 SUMOylation. The data generated will provide critical insights on the post- translational regulation of NS1 function and the molecular effects mediated by SUMOylation during influenza virus infection, and potentially lead to the identification of novel targets for the development of broad-spectrum anti-influenza therapies. Additionally, these studies will also expand our understanding of the interactions established between viruses and the cellular SUMOylation system.