The Role of TRIM23 in Autophagy Mediated Antiviral Defenses

项目概要 自噬是细胞处理细胞内容物的过程，已被 作为抗病毒宿主防御的重要途径越来越受到重视。有趣的是，最近 研究表明，自噬和抗病毒 I 型 IFN 反应错综复杂 连接，并且已知在 IFN 介导的免疫中发挥关键作用的几种分子也 自噬的重要调节因子。在这些具有自噬和自噬双重作用的分子中 IFN 介导的免疫是 TRIM（三联基序）蛋白家族的几个成员。然而， 而 TRIM 蛋白作为抗病毒限制因子的分子机制或 调节 IFN 反应已经得到很好的表征，我们对 TRIM 作用的了解 响应病毒感染的自噬蛋白仍处于初级阶段。 拟议的研究建立在 Gack 实验室最近的一项发现的基础上，该发现确定了 TRIM23 作为自噬介导的宿主防御多种疾病的关键调节因子 病毒。 TRIM23 与先天免疫分子 TBK1 相互作用并激活，促进 TBK1 介导的选择性自噬受体 p62 磷酸化，最终 触发病毒清除和宿主抵抗。从机制上讲，N 端 RING E3 连接酶 TRIM23 诱导 C 端 ARF 的非典型非降解 K27 连接自动泛素化 GTPase 结构域，TRIM23 所特有。 ARF 泛素化导致 ARF 活性增强 TRIM23 水解 GTP、激活 TBK1 并介导病毒抵抗力。 TRIM23 耗尽或 多种细胞类型的基因靶向表明 TRIM23 介导的自噬具有抗病毒作用 对包括 HSV-1 在内的多种病毒具有活性。 使用分子、生化、细胞生物学和结构方法相结合 病毒感染研究中，我们将详细定义 TRIM23 在病毒感染过程中如何介导自噬 病毒感染。这项研究将通过以下方式深入了解 TRIM23 激活机制 病毒感染期间的上游调节因子（目标 1）。我们将进一步确定分子 TRIM23 如何激活 TBK1 以及 TRIM23 酶活性的作用的详细信息 – E3 连接酶和 GTPase – 在 TBK1 激活中发挥作用。最后，我们将确定生理 使用体外细胞研究 TRIM23 与抗病毒宿主耐药性和病毒发病机制的相关性 TRIM23 敲除小鼠的培养系统和感染研究（目标 2）。我们的研究将提供 对自噬介导的宿主防御中关键途径的分子理解， 可以指导新型抗病毒药物的合理设计。

PROJECT SUMMARY Autophagy, the process by which cells dispose of cellular contents, has been increasingly appreciated as an important pathway in antiviral host defenses. Intriguingly, recent studies demonstrated that autophagy and the antiviral type I IFN response are intricately connected, and several molecules known to play key roles in IFN-mediated immunity are also important regulators of autophagy. Among these molecules with dual roles in autophagy and IFN-mediated immunity are several TRIM (tripartite motif) protein family members. However, whereas the molecular mechanisms by which TRIM proteins act as antiviral restriction factors or regulate IFN responses have been well characterized, our knowledge about the role of TRIM proteins in autophagy in response to viral infection is still rudimentary. The proposed study builds on a recent discovery by the Gack laboratory that identified TRIM23 as a critical regulator of autophagy-mediated host defense against a broad range of viruses. TRIM23 interacts with and activates the innate immune molecule TBK1, promoting TBK1-mediated phosphorylation of the selective autophagy receptor p62, which ultimately triggers viral clearance and host resistance. Mechanistically, the N-terminal RING E3 ligase of TRIM23 induces atypical non-degradative K27-linked auto-ubiquitination of the C-terminal ARF GTPase domain, which is unique to TRIM23. ARF ubiquitination results in enhanced activity of TRIM23 to hydrolyze GTP, activate TBK1, and mediate virus resistance. TRIM23 depletion or gene-targeting in various cell types showed that TRIM23-mediated autophagy confers antiviral activity against several viruses including HSV-1. Using molecular, biochemical, cell biological and structural approaches combined with virus infection studies, we will define in precise detail how TRIM23 mediates autophagy during viral infection. This study will yield insight into the mechanisms of TRIM23 activation by upstream regulators during viral infection (Aim 1). We will further determine the molecular details of how TRIM23 activates TBK1 and the role the enzymatic activities of TRIM23 – E3 ligase and GTPase – play in TBK1 activation. Finally, we will determine the physiological relevance of TRIM23 for antiviral host resistance and viral pathogenesis using in vitro cell culture systems and infection studies in TRIM23 knockout mice (Aim 2). Our studies will provide a molecular understanding of a key pathway in the autophagy-mediated host defense, which may guide the rational design of new antivirals.