Cellular Mechanism of Oxysterol-Binding Protein (OSBP) in Viral Proliferation: A Chemical Biology Approach

当前的COVID-19危机清楚地表明，有必要开发新的模式， 病原性单链RNA（ssRNA）病毒的治疗性治疗，包括针对 尚未出现的新型病毒。人氧固醇结合蛋白（OSBP）最近 已被确定为广谱ssRNA病毒复制的关键介质 人类病原体，包括肠道病毒、鼻病毒、丙型肝炎、寨卡病毒、登革热 病毒和冠状病毒。OSBP是一种位于内质网的非酶蛋白， 作为真核细胞中重要的脂质感受器和脂质转运体。已发表的研究，包括 我们自己最近的出版物，已经建立了结构多样的OSBP的抗病毒活性， 靶向小分子对抗多种RNA致病病毒。这些发现表明， 抗病毒药物开发范式转变的机会：潜在的药物靶向 一种广谱RNA病毒增殖所需的人类宿主蛋白，OSBP 病毒，而不是针对存在于单个病毒中的病毒蛋白。我们已经发现 用靶向OSBP的化合物OSW-1-化合物的瞬时低剂量治疗诱导 OSBP的长期、多代抑制，并且具有抑制的OSBP的细胞显示出 显著抑制ssRNA病毒复制。我们的初步结果表明，OSW-1- 化合物在低纳摩尔浓度下具有预防性抗病毒活性 ssRNA病毒，包括测试的一种冠状病毒。OSBP的长期抑制， 由OSW-1触发，对细胞分裂、活力或形态没有影响。 本提案的目的是了解OSBP在先天性抗病毒治疗中的细胞作用。 反应我们的初步结果表明OSBP：1）调节mTORC 1活性，2）诱导 自噬; 3）减缓整体蛋白质翻译;和4）激活选择性剪接无义- 介导的衰变（AS-NMD）过程，其是RNA调节过程。所有这些OSBP- 参与的细胞过程会限制ssRNA病毒的复制，但目前还没有什么研究成果。 进入这些系统的组织，以建立一个协调的抗病毒反应。我们的整体 假设是OSBP在协调多方面先天性 抗病毒反应ssRNA感染。我们提出了一个完整的模型，OSBP如何感觉早期- 阶段性病毒感染，然后触发多系统反应以阻断病毒在细胞中复制， 包括通过调节mTOR 1C活性和AS-NMD系统。

The current COVID-19 crisis starkly illustrates the need to develop new modalities for the therapeutic treatment of pathogenic single-stranded RNA (ssRNA) viruses, including against novel viruses that have yet to emerge. Human oxysterol-binding protein (OSBP) has recently been determined to be a critical mediator in the replication of a broad spectrum of ssRNA viral human pathogens, including the enteroviruses, rhinovirus, hepatitis C, Zika virus, Dengue fever viruses, and coronaviruses. OSBP is an ER-located, non-enzymatic protein reported to function as an important lipid sensor and lipid transporter in eukaryotic cells. Published research, including our own recent publications, has established the antiviral activity of structurally-diverse OSBP- targeting small molecules against multiple RNA pathogenic viruses. These discoveries present the opportunity for a paradigm shift in antiviral drug development: potentially drug targeting a human host protein, OSBP, that is required for viral proliferation of a broad-spectrum of RNA viruses, as opposed to targeting viral proteins present in individual viruses. We have discovered that transient, low dose treatment with the OSBP-targeting compound OSW-1-compound induces a longterm, multigenerational repression of OSBP, and the cells with repressed OSBP show a pronounced inhibition of ssRNA viral replication. Our preliminary results show that the OSW-1- compound has prophylactic antiviral activity at low nanomolar concentrations against several ssRNA viruses, including against one coronavirus tested. The longterm repression of OSBP, triggered by OSW-1, has no effect on cellular division, viability, or morphology. The purpose of this proposal is to understand the cellular role of OSBP in innate antiviral response. Our preliminary results show that OSBP: 1) regulates mTORC1 activity, 2) induces autophagy; 3) slows global protein translation; and 4) activates alternative splicing nonsense- mediated decay (AS-NMD) process, which is an RNA regulatory process. All of these OSBP- involved cellular processes would limit ssRNA viral replication individually, but there is little insight into the organization of these systems to establish a coordinated antiviral response.Our overall hypothesis is that OSBP serves in a major regulatory role to coordinate a multifaceted innate antiviral response to ssRNA infection. We propose a complete model of how OSBP senses early- stage viral infection and then triggers a multisystem response to block viral replication in cells, including through modulating mTOR1C activity and the AS-NMD system.