Virus Wars: Are E3-Targeted Therapies A New Hope?

病毒感染在世界各地造成了无法量化的疾病、死亡和社会经济负担。一些病毒似乎太难以预防，抗病毒药物最终也会失败，因为它们会对病毒靶标产生抗药性。现在迫切需要新的抗病毒药物。我的研究计划的主要目标是加快开发“宿主导向疗法”，这是一种有前途的针对病毒蛋白的抗病毒药物的替代品。要做到这一点，我首先想知道哪些是宿主细胞对病毒感染做出反应的相关参与者。一种常见的假设是，细胞仅仅通过改变它们的相对丰度来调节它们的酶。我们了解到(并普遍同意)翻译后控制是重要的，但测量这一点比评估基因表达或蛋白质丰度要棘手得多，随着时间的推移，这已成为“活性”的替代品。邓迪大学的一个实验室设计了一种巧妙的方法，专门测量一种特定类型的酶的活性(而不是丰度)，这种酶在细胞生物学的方方面面都具有深远的重要性--E3泛素连接酶(E3)。E3的作用就像“粘贴枪”，通过一种名为泛素的小蛋白质修饰来标记其他蛋白质。泛素标记的蛋白质通常被送到细胞的分子废物处理系统进行回收利用。众所周知，一些E3有助于病毒感染的进展(有利于病毒)，而另一些则阻碍感染的进展(抗病毒)。操纵这些活动可能会带来控制病毒感染的新的创新疗法。这项技术被称为“基于活动的探针”(ABP)，它通过模仿E3的主要生命伴侣--E2泛素结合酶(E2)来工作。E2S与细胞中的活性E3s瞬时结合；基于E2的ABP不可逆转地与E3s结合，捕获它并泄露其先前的激活状态。因此，使用总部基地让我能够从“小麦和谷壳中挑选出”，并发现当我们谈论“宿主导向疗法”时，我们应该关注哪些E3。三种特别有害的感染几乎没有减弱的迹象，它们是人类免疫缺陷病毒(HIV)和甲型流感病毒(IAV)。艾滋病毒是一种大流行感染；IAV有可能大流行。使用这两种病毒感染模型，我将在宿主的E3活动反应中寻找共同和不同的“分子特征”，这可能标志着新疗法的道路。我会用病毒感染细胞，然后派总部基地组织的侦察员进入受感染的细胞，在那里他们揭示感染过程中E3活动变化的全景。在我们的细胞中识别趋同的分子特征甚至可能标志着广谱宿主导向疗法的道路。

Viral infections are responsible for an unquantifiable amount of disease, death and socioeconomic burden around the world. Some viruses seem too evasive to vaccinate against and antiviral drugs ultimately fail because they cause resistance in their viral targets. There is an urgent need for new classes of antiviral medicines.The main objective of my research proposal is to fast-track the development of 'host-directed therapies', a promising alternative to antiviral drugs that target viral proteins.To do this, I first want to understand which are the relevant participants of a host cell's response to viral infection. A frequently held assumption is that cells regulate their enzymes simply by changing their relative abundance. We learn (and generally agree) that post-translational control is important, but measuring this has been much trickier than assessing gene expression or protein abundance, which have over time become a surrogate for 'activity'. A lab at the University of Dundee have designed an ingenious way to specifically measure the activity (rather than the abundance) of a particular class of enzyme that has profound importance in all aspects of cell biology - the 'E3 ubiquitin ligase' (E3).E3s act like 'sticker-guns', labelling other proteins with a small protein modification called ubiquitin. Ubiquitin-labelled proteins are most commonly sent to the cell's molecular waste disposal system for recycling. Some E3s are known to help viral infections progress (pro-viral) while others hinder the progression of infection (antiviral). Manipulating these activities could lead to new innovative therapies to control viral infections.The technology - called an 'Activity-based probe' (ABP) - works by mimicking the E3s main partner in life, the E2 ubiquitin conjugating (E2) enzyme. E2s bind transiently to active E3s in cells; an E2-based ABP binds irreversibly to E3s, trapping it and divulging its prior state of activation. So, using the ABP allows me to sort the 'wheat from the chaff' and discover which E3s we should be focusing on when we talk about 'host-directed therapy'.Three particularly pernicious infections which show few signs of abating are human immunodeficiency virus (HIV) and influenza A virus (IAV). HIV is a pandemic infection; IAV has the potential for pandemics. Using these two virus infections models, I will look for common and divergent 'molecular signatures' in the host's E3 activity response that might signpost the way to novel therapies. I will infect cells with a virus, and then send the ABP scouts inside the infected cell, where they reveal a panorama of E3 activity change during the course of infection. Identifying convergent molecular signatures in our cells might even signpost the way to broad-spectrum host-directed therapies.