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

当前的新冠肺炎危机鲜明地表明，有必要为 致病性单链RNA病毒的治疗，包括针对 尚未出现的新病毒。人类氧固醇结合蛋白(OSBP)最近 被确定为复制广谱单链RNA病毒的关键媒介 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是一种内质网定位的非酶蛋白，据报道具有功能 作为真核细胞中重要的脂质感受器和脂质转运体。已发表的研究成果，包括 我们自己的最新出版物，已经确定了结构多样化的OSBP的抗病毒活性- 靶向小分子对抗多种RNA致病病毒。这些发现展示了 抗病毒药物开发范式转变的机会：潜在的药物靶向 人类宿主蛋白，OSBP，是病毒增殖广谱RNA所必需的 病毒，而不是针对存在于单个病毒中的病毒蛋白。我们发现 OSBP靶向化合物OSW-1化合物的短暂、低剂量治疗诱导 OSBP的长期、多代抑制，OSBP抑制的细胞显示 明显抑制单链RNA病毒复制。我们的初步结果显示，OSW-1- 化合物在低纳米分子浓度下对几种病毒具有预防性抗病毒活性 单链RNA病毒，包括针对一种被测试的冠状病毒。对OSBP的长期压制， 由OSW-1触发，对细胞分裂、活性或形态没有影响。 这项建议的目的是了解OSBP在先天抗病毒中的细胞作用。 回应。我们的初步结果表明，OSBP：1)调节mTORC1活性，2)诱导 自噬；3)减缓全球蛋白质翻译；4)激活替代剪接胡说八道- 介导的衰变(AS-NMD)过程，这是一个RNA调节过程。所有这些OSBP- 涉及的细胞过程会限制单链RNA病毒的复制，但几乎没有洞察力 组织这些系统，以建立协调的抗病毒反应。我们的总体 假说是OSBP起着重要的调节作用，以协调多方面的先天 对单链RNA感染的抗病毒反应。我们提出了一个完整的OSBP早期感觉模型- 病毒感染阶段，然后触发多系统反应，阻止病毒在细胞内复制， 包括通过调节mTOR1C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.