Regulatory and Mechanistic Understanding of ADAR-Mediated RNA Editing

项目概要/摘要 先天免疫控制良好，能够及时、灵敏地应对病原感染，同时 容忍细胞中的“自我”分子。先天免疫调节的缺陷会导致各种疾病， 例如自身免疫性疾病或更容易受到感染。我们和其他人之前的研究重新 vealed ADAR1，一种 RNA 编辑酶，可催化 dsRNA 上的腺苷到肌苷 (A-to-I) 编辑，作为 双链RNA（dsRNA）先天免疫反应调节中的关键角色。 ADAR1 RNA 编辑 结合活性已被证明可以防止内源性（“自身”）dsRNA 激活胞质 dsRNA 传感器 MDA5 和 PKR，但其潜在的分子机制尚不清楚。此外， ADAR1 p150 同种型对至少一些 dsRNA 的细胞质编辑对于抑制 dsRNA 至关重要 介导的自身免疫，尽管细胞核中的 ADAR1 p110 亚型通常要丰富得多。如何 这些 dsRNA 是在细胞质中编辑的，而不是在细胞核中编辑的吗？ 在此 MIRA 应用程序中，我们重点关注两个项目来解决这些知识差距。首先，我们将阐明 ADAR1 与 dsRNA 先天免疫途径中其他参与者之间的相互作用。具体来说，我们将投资—— 揭示 ADAR1 调节 dsRNA 传感的 MDA5 和 PKR 通路的机制。我们建议 ADAR1 在 RNA 编辑依赖性和非依赖性 fash 中调节 dsRNA 介导的先天免疫 离子。我们将研究这两种作用模式如何在体外发挥作用，并测试它们在小鼠体内的影响 模型。其次，我们将揭示细胞质与核编辑的调控机制。具体来说，我们 将进行遗传筛选和生化测定，以识别和表征导致疾病的因素 编辑中的空间差异。总而言之，这些创新研究将提供对 先天免疫中 dsRNA 编辑和 dsRNA 传感界面的分子机制。

PROJECT SUMMARY/ABSTRACT The innate immunity is well-controlled to respond to pathogenic infection in a timely and sensitive manner, while tolerating “self” molecules in the cell. Defects in the regulation of innate immunity result in various disorders, such as autoimmune diseases or heightened vulnerability to infections. Previous studies by us and others re- vealed ADAR1, an RNA editing enzyme that catalyzes Adenosine to Inosine (A-to-I) editing on dsRNAs, as a key player in the regulation of innate immune response to double-stranded RNAs (dsRNAs). ADAR1 RNA editing and binding activities have been shown to prevent endogenous (“self”) dsRNAs from activating the cytosolic dsRNA sensors MDA5 and PKR, but the underlying molecular mechanisms are not well understood. In addition, the cytoplasmic editing of at least some dsRNAs by the ADAR1 p150 isoform is crucial to suppress the dsRNA- mediated autoimmunity, although the ADAR1 p110 isoform in the nucleus is generally a lot more abundant. How are these dsRNAs edited in the cytoplasm but not in the nucleus? In this MIRA application, we focus on two projects to address these knowledge gaps. First, we will elucidate the interplay between ADAR1 and other players in the dsRNA innate immunity pathways. Specifically, we will inves- tigate the mechanisms by which ADAR1 regulates the MDA5 and PKR pathways of dsRNA sensing. We propose that ADAR1 regulates dsRNA-mediated innate immunity in both RNA editing-dependent and -independent fash- ion. We will study how these two modes of action operate in vitro and test their in vivo implications in mouse models. Second, we will uncover the regulatory mechanisms for cytoplasmic vs. nuclear editing. Specifically, we will perform genetic screens and biochemical assays to identify and characterize the factors responsible for spatial differences in editing. Taken together, these innovative studies will provide a deep understanding of the molecular mechanisms operating at the interface of dsRNA editing and dsRNA sensing in innate immunity.