Subversion of cGAS DNA sensing by KSHV: Roles of ORF52/KicGAS

KSHV 颠覆 cGAS DNA 传感：ORF52/KicGAS 的作用

• 批准号: 9204145
• 负责人: FANXIU ZHU
• 金额: $ 37.13万
• 依托单位: FLORIDA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9204145
• 关键词: AIDS related cancer; Acquired Immunodeficiency Syndrome; Adaptor Signaling Protein; Agonist; Amino Acids; Antiviral Agents; Antiviral Response; Autoimmune Diseases; Autoimmunity; Binding; Cells; Complex; Cyclic GMP; DNA; DNA Tumor Viruses; Development; Dinucleoside Phosphates; Disease; Dissection; Endothelial Cells; Genes; Goals; Health; Herpesviridae Infections; Human; Human Herpesvirus 8; Immune; Immune response; Immunity; Infection; Inflammatory; Interferon Type I; Interferons; Intervention; Kaposi Sarcoma; Knowledge; Lead; Learning; Lesion; Life Cycle Stages; Ligands; Malignant Neoplasms; Maps; Mediating; Molecular; Multicentric Angiofollicular Lymphoid Hyperplasia; Names; Oncogenic Viruses; Oral cavity; Outcome; Pathogenesis; Pathway interactions; Pattern; Play; Prevention strategy; Primary Infection; Production; Proteins; Reporting; Research; Role; Saliva; Second Messenger Systems; Signal Transduction; Site; Structure; T-Lymphocyte; Testing; Therapeutic Intervention; Viral; Virion; Virus; Virus Diseases; Virus Inhibitors; Work; antitumor effect; infectious disease treatment; inhibitor/antagonist; insight; lytic replication; novel therapeutics; pathogen; prevent; primary effusion lymphoma; response; second messenger; sensor; transmission process; tumor; viral DNA

1. ABSTRACT Kaposi's sarcoma–associated herpesvirus (KSHV) is a large DNA tumor virus that is the causative agent of Kaposi sarcoma (KS), the most prevalent AIDS-associated malignancy. KS is an angiogenic and inflammatory tumor of endothelial cell origin. It often manifests in the oral cavity, the major site for KSHV shedding and transmission via saliva. KSHV persistently infects the spindle cells of endothelial cell origin in KS tumors. In order to persist, the virus must overcome the host antiviral response. The host cells initiate antiviral response upon recognition of virus-derived moieties, including viral DNA, through innate immune sensors. Cyclic GMP- AMP synthase (cGAS) is the major sensor responsible for the recognition of cytosolic DNA. Upon binding to DNA, cGAS catalyzes the synthesis of cyclic GMP-AMP (cGAMP). This cyclic dinucleotide molecule acts as second messenger to activate the adaptor STING (stimulator of interferon genes) leading to induction of interferon (IFN) antiviral responses. Although herpesviral DNA constitutes a significant PAMP (pathogen- associated molecular pattern) within incoming virions, recurring episodes of lytic replication in KS lesions cause negligible IFN antiviral responses. This observation suggests that KSHV must have evolved an effective mechanism to subvert cGAS DNA-sensing. Emerging evidence indicates that cGAS-STING pathway is not only crucial for antiviral responses but also for antitumor immunity. Therefore, elucidating the underlying mechanisms by which KSHV subverts cGAS DNA sensing is crucial for understanding KS pathobiology. We recently found that KSHV can elicit cGAS-dependent DNA sensing responses. More importantly, we revealed that a KSHV virion protein, ORF52, subverts cytosolic DNA sensing by inhibiting cGAS enzymatic activity. This is the first viral inhibitor of cGAS to be reported and we rename it KicGAS (KSHV inhibitor of cGAS). Our long- term goal is to understand how KSHV evades the host innate antiviral responses, with an emphasis on the roles of virion-contained tegument proteins. The objective here is to define the molecular mechanisms by which KicGAS inhibits cGAS, and to determine the roles of KicGAS throughout the KSHV life cycle. Our central hypothesis is that KicGAS, as a virion-contained cGAS antagonist, plays crucial roles during KSHV primary infection and lytic replication. We will test our hypothesis by pursuing the following specific aims: 1) To elucidate the molecular mechanisms by which KicGAS inhibits cGAS DNA sensing. 2) To reveal the roles of KicGAS in KSHV lytic replication. 3) To determine the roles of cGAS and KicGAS during KSHV infection of KS- relevant cells. The work proposed here is expected to offer new insights into the molecular mechanisms by which viruses subvert cGAS DNA sensing, and to reveal the roles of KicGAS in the KSHV life cycle. Such results are expected to have an important positive impact, because the identified mechanisms can aid in the development of agonists or antagonists of the cGAS-cGAMP pathway, which can then be used for therapeutic intervention to treat or prevent KSHV-associated diseases.

1。摘要 卡波西（Kaposi）的肉瘤相关疱疹病毒（KSHV）是一种大型DNA肿瘤病毒 Kaposi肉瘤（KS），最普遍的艾滋病相关性恶性肿瘤。 KS是一种血管生成和炎症 内皮细胞起源的肿瘤。它经常在口腔中表现出来，这是KSHV脱落的主要地点 通过唾液传播。 KSHV持续感染KS肿瘤中内皮细胞起源的纺锤体细胞。在 为了持久，病毒必须克服宿主抗病毒药反应。宿主细胞启动抗病毒反应 通过识别病毒衍生的部分，包括病毒DNA，通过先天免疫传感器。循环GMP- AMP合酶（CGAS）是负责识别胞质DNA的主要传感器。结合到 DNA，CGA催化环状GMP-AMP（CGAMP）的合成。这种环状二核苷酸分子充当 第二使者激活辅助刺激器（干扰素基因的刺激剂），导致诱导 干扰素（IFN）抗病毒反应。尽管疱疹病毒DNA构成显着的症状（病原体 - 在传入病毒中的相关分子模式），ks病变中裂解复制的反复发作 导致可忽略的IFN抗病毒反应。该观察结果表明，KSHV必须发展有效 颠覆CGAS DNA感应的机制。新兴的证据表明CGAS刺道途径不是 仅对抗病毒反应至关重要，也对抗肿瘤免疫力至关重要。因此，阐明了基础 KSHV颠覆CGAS DNA感应的机制对于理解KS病理生物学至关重要。我们 最近发现，KSHV可以引起CGAS依赖性DNA感应反应。更重要的是，我们揭示了 KSHV病毒素蛋白ORF52通过抑制CGAS酶活性来颠覆胞质DNA感测。这 是第一个要报告的CGA的病毒抑制剂，我们将其重命名为Kicgas（CGAS的KSHV抑制剂）。我们的长期 术语目标是了解KSHV如何逃避宿主先天的抗病毒反应，并重点是 含病毒体的Tegument蛋白的作用。这里的目的是通过 Kicgas抑制了CGA，并确定Kicgas在整个KSHV生命周期中的作用。我们的中心 假设是Kicgas作为具有病毒体的CGA拮抗剂，在KSHV初级中起着至关重要的作用 感染和裂解复制。我们将通过追求以下特定目的来检验我们的假设：1） 阐明了Kicgas抑制CGAS DNA敏感性的分子机制。 2）揭示角色 KSHV裂解复制中的Kicgas。 3）确定CGA和KICGA在KS- KSHV感染中的作用 相关细胞。预计此处提出的工作将提供有关分子机制的新见解 该病毒颠覆了CGAS DNA感应，并揭示了Kicgas在KSHV生命周期中的作用。这样的 预计结果将产生重要的积极影响，因为确定的机制可以帮助 CGAS-CGAMP途径的激动剂或拮抗剂的发展，然后可以用于治疗 干预以治疗或预防KSHV相关疾病。