Understanding the interplay between coxsackievirus and the host ubiquitin-proteasome system

正RNA病毒，其所有遗传信息都包含在一条正RNA链中，占所有病毒属的三分之一以上，并在植物、动物和人类中引起各种疾病。为了确保成功感染，这个家族的病毒已经进化到利用宿主细胞机制，如泛素-蛋白酶体系统（UPS）来支持它们的生命周期。蛋白酶体是一个大的细胞复合体，它可以分解被称为泛素的小蛋白质标记的不需要的或受损的蛋白质。除了影响靶蛋白的稳定性外，泛素的附着也可以改变底物蛋白的功能/活性，而不会使底物蛋白降解。在本研究项目中，我们将使用柯萨奇病毒作为模型生物来了解正链RNA病毒如何与宿主UPS相互作用以实现成功的生产。我们的假设是柯萨奇病毒破坏了这个系统，通过调节宿主和病毒蛋白的丰度和功能来支持其感染。我们之前发现，泛素的消耗或蛋白酶体活性的抑制显着减少病毒复制，提示UPS在柯萨奇病毒感染中的重要作用。此外，我们发现柯萨奇病毒也利用泛素非依赖性蛋白酶体介导的降解来促进病毒生长。然而，确切的作用机制尚未阐明。在这里，我们建议研究由于柯萨奇病毒感染而导致UPS失调的分子基础和控制病毒复制的潜在机制。具体来说，我们将结合使用尖端的蛋白质组学方法与传统的分子和细胞技术来研究病毒蛋白如何操纵UPS，并确定UPS中调节病毒感染性的关键酶和靶蛋白。我们还将剖析泛素介导的病毒蛋白修饰的功能意义。这项研究探索了一种新的基于蛋白酶体的机制，它将改变我们对病毒如何破坏宿主细胞机制的理解。从这个项目中获得的知识也将对同一家族中其他病毒的宿主-病原体相互作用的研究具有更广泛的意义。

Positive RNA viruses, which have all their genetic information in a single positive-strand of RNA, encompass more than one-third of all virus genera and cause various diseases in plants, animals, and humans. To ensure successful infection, viruses in this family have evolved to exploit the host cellular machinery, such as the ubiquitin-proteasome system (UPS), to support their lifecycle. The proteasome is a large cellular complex that breaks down unwanted or damaged proteins that have been marked with a small protein called ubiquitin. Apart from influencing the stability of the target proteins, attachment of ubiquitin can also change the function/activity of substrate proteins without targeting them for degradation. In this research program, we will use coxsackievirus as a model organism to understand how positive-strand RNA viruses interact with the host UPS to achieve successful production. Our hypothesis is that coxsackievirus subverts this system to support its infection by regulating the abundance and function of host and viral proteins. We previously discovered that depletion of ubiquitin or inhibition of the proteasome activity markedly reduces viral replication, suggesting an important role for the UPS in coxsackieviral infection. In addition, we found that ubiquitin-independent proteasome-mediated degradation is also utilized by coxsackievirus to promote viral growth. However, the exact mechanism of action has not been elucidated. Here we propose to study the molecular basis responsible for the dysregulation of the UPS as a consequence of coxsackievirus infection and the underlying mechanisms by that control viral replication. Specifically, we will combine the use of cutting-edge proteomics approaches with conventional molecular and cellular technologies to investigate how viral proteins manipulate the UPS and to identify the critical enzymes and target proteins within the UPS that regulate viral infectivity. We will also dissect out the functional significance of ubiquitin-mediated modification of viral proteins. This research explores a novel proteasome-based mechanism that will change our understanding of how viruses subvert the host cellular machinery. Knowledge gained from this program will also have broader implications for the study of host-pathogen interaction of other viruses in the same family.