Viral manipulation of DBC1: a novel strategy to promote cell survival and suppress inflammation

人类和动物的细胞都有非常复杂的网络来沟通和应对压力。病毒感染是一种压力，可以导致细胞死亡。因此，细胞对病毒感染反应强烈，目的是阻止病毒繁殖，并提醒身体的免疫系统正在进行感染。只有有能力避免这种敌对细胞反应的病毒才能存活。病毒是如何做到这一点的并不总是很清楚。然而，如果这些病毒策略中的一种被发现，就会出现开发抗病毒干预措施的机会。这个项目涉及发现一组被称为痘病毒的病毒所采用的策略之一，其中一种病毒导致了毁灭性的疾病天花。在有记载的历史中，天花病毒导致的死亡人数超过了所有其他传染病的总和，但幸运的是，由于使用痘病毒家族的另一成员牛痘病毒（VACV）的全球疫苗接种运动，天花病毒被根除了。目前正在研究VACV作为另一种被称为猴痘的天花样疾病以及其他几种重要的人类和动物疾病（如结核病、艾滋病或狂犬病）的疫苗。这个项目将研究痘病毒如何操纵一种叫做DBC1的细胞蛋白的活性。DBC1属于细胞用来应对外部压力的通讯网络之一。它的主要作用是阻断另一种被称为SIRT1的蛋白质的作用。DBC1和SIRT1都是大约10年前才被发现的，所以我们对它们如何工作的理解仍处于起步阶段。然而，现在清楚的是，DBC1和SIRT1在衰老过程和与年龄相关的疾病（如癌症和慢性炎症）中都非常重要。该项目表明，痘病毒特异性结合并重新定位SIRT1的负调节因子DBC1，在SIRT1通常不存在的细胞部分。这表明痘病毒破坏了DBC1-SIRT1连接，并以许多尚未完全了解的方式从中受益。因此，该项目将确定1)痘病毒如何将DBC1从SIRT1中分离出来，2)这对病毒有什么好处，以及3)这种病毒行为在疾病和疫苗接种中有什么后果。为了解决这一问题，将开展详细的分子生物学和蛋白质定位研究。为了解决其中的原因，我们将在先前修改为缺乏DBC1， SIRT1或两种基因的细胞中进行一系列功能测试。这些细胞对感染的反应将被研究，并与正常细胞进行比较。这些研究的结论将首次确定DBC1- sirt1轴在病毒感染过程中的作用，并将不仅为新出现的痘病毒（如猴痘病毒）提供有价值的信息，而且可能也为具有类似生物学的其他病毒（如非洲猪瘟病毒）提供有价值的信息。非洲猪瘟病毒是一种新兴的、具有重要经济意义的猪病原体，也可能隔离DBC1。最后，考虑到VACV作为疫苗的重要性，该项目将研究DBC1- sirt1轴在疫苗接种中的影响，使用实验室修饰的病毒来重新定位DBC1或不定位DBC1。对疫苗接种的反应是复杂的，并且随着年龄的增长而变化。如果不破坏DBC1-SIRT1连接的修饰病毒引发更好的免疫反应，则可以将这种修饰引入目前正在开发的基于vacv的疫苗中。因此，这个项目有可能对疫苗的设计产生影响，并提高我们对衰老及其生物学的理解。

Human and animal cells have very sophisticated networks to communicate and respond to stress. Infection by a virus is a stress that can lead to the death of the cell. Accordingly cells respond vigorously to viral infection with the aim of blocking viral multiplication and alerting the body's immune system to the ongoing infection. Only viruses that have the capacity to avoid this hostile cell response survive. How viruses achieve this is not always clear. However, if and when one of these viral strategies is discovered, an opportunity for the development of antiviral interventions emerges. This project concerns the discovery of one of those strategies employed by a group of viruses named poxviruses, a member of which was responsible for the devastating disease smallpox. The smallpox virus killed more people in recorded history than all other infectious diseases combined, but fortunately was eradicated thanks to a worldwide vaccination campaign that used vaccinia virus (VACV), another member of the poxvirus family. VACV is currently being studied as a vaccine against another smallpox-like disease known as monkeypox as well as other several important human and animal diseases such as tuberculosis, AIDS, or rabies. This project will study how poxviruses manipulate the activity of a cellular protein termed DBC1. DBC1 belongs to one of those communication networks that cells use to respond to external stress. Its main role is to block the action of another protein known as SIRT1. Both DBC1 and SIRT1 were only discovered ~10 years ago, so our understanding of how they work is still in its infancy. However, it is now clear that both DBC1 and SIRT1 are very important in the process of ageing and in age-related diseases such as cancer and chronic inflammation. This project demonstrates that poxviruses specifically bind and relocalise DBC1, the negative regulator of SIRT1, in a part of the cell where SIRT1 is not normally present. This suggests that poxviruses break the DBC1-SIRT1 connection and benefit from this in a number of ways that are not fully understood yet. This project will therefore determine 1) how poxviruses sequester DBC1 away from SIRT1, 2) what advantage this has for the virus, and 3) what consequences this viral action has in disease and vaccination. To address how, detailed molecular biology and protein localisation studies will be developed. To address why, we will conduct a series of functional tests in cells previously modified to lack DBC1, SIRT1 or both genes. The response of these cells to infection will be studied and compared to that of normal cells. The conclusions from these studies will establish for the first time the role of the DBC1-SIRT1 axis during infection with viruses, and will provide valuable information not only for emerging poxviruses such as the monkeypox virus, but perhaps also for other viruses with similar biology such the African Swine Fever virus - an emerging, economically important pig pathogen that might also sequester DBC1.Finally, given the importance of VACV as a vaccine, the project will study the impact of the DBC1-SIRT1 axis in vaccination using viruses modified in the laboratory to relocate DBC1 or not. The response to vaccination is known to be complex and to change with age. If the modified virus that does not break the DBC1-SIRT1 connection triggers a better immune response, this modification can be introduced into VACV-based vaccines that are currently being developed. Therefore this project has the potential to impact on the design of vaccines and to improve our understanding of ageing and its biology.