RNA editing in islet function and inflammation

RNA 编辑是一个基本的细胞过程，涉及细胞中某些腺苷的脱氨基作用。 RNA 通过腺苷脱氨酶 Adar1 (ADAR) 和 Adar2 (ADARB1) 转化为肌苷。 最近的研究表明，RNA 编辑的一个关键作用是破坏双链 RNA (dsRNA) 结构，由反向插入基因组中的逆转录元件生成 表达基因内的方向。由这样的序列构型形成的dsRNA是 古老的抗病毒干扰素反应的强大而危险的激活剂，可能会导致 致病性炎症。虽然RNA编辑已经在一些器官的背景下进行了研究 在癌症中，人们对 ADAR 酶在胰岛细胞功能和功能中的作用知之甚少。 健康。我们的目标是阐明 RNA 编辑在胰岛中的作用，特别是在 α 和 β细胞。引人注目的是，1 型糖尿病 (T1D) 的 GWAS 研究揭示了保护性变异 IFIH1/MDA5 是一种胞质受体，可识别来自任一来源的双链 RNA (dsRNA) 病毒或内源性起源，并引起炎症反应。因此，有缺陷的RNA编辑 原则上可以促进先于自身免疫的胰岛抗病毒反应。我们 假设β细胞中的RNA编辑和内源dsRNA的积累受损 触发 IFIH1 依赖性干扰素反应，导致胰岛炎症，从而导致 β 细胞功能障碍并可能导致自身免疫。在我们的初步调查结果中，我们发现 成年小鼠体内或人胰岛β细胞中A-to-I RNA编辑的破坏会引发 干扰素反应。在 Adar1 缺陷型 β 细胞小鼠中，这会导致大量免疫 反应局限于胰岛，包括先天免疫细胞和 T 细胞。阿尔法细胞出现 抵抗因 β 细胞中 Adar1 缺陷而导致的 Adar1 破坏或胰岛炎症。 我们建议 1) 在 RNA 遗传破坏后表征小鼠和人类胰岛细胞 通过敲除或敲低关键 RNA 编辑酶 Adar1 进行编辑； 2）检查 Adar1 缺陷对 β 和 α 细胞功能和活力以及胰岛的影响 炎症和自身免疫； 3）研究差异的分子基础 α 和其他胰岛细胞类型对 Adart1 的依赖性。拟议的研究是一项接近 三个具有互补专业知识的团队之间的合作：Al Powers（人类胰岛生物学 和功能）、Yuval Dor（小鼠模型、分子生物学）和 Erez Levanon（计算 RNA 编辑分析）。这项工作将阐明 RNA 编辑的作用，这是一个关键 胰岛细胞中的表观转录组修饰。它还将反驳或提供临床前支持 RNA 编辑缺陷可能与 1 型糖尿病的某些方面有关的挑衅性假设 发病机制，特别是早期的抗病毒炎症反应。 1

RNA editing, a fundamental cellular process, involves the deamination of some adenosines in RNA to inosines, by the adenosine deaminases Adar1 (ADAR) and Adar2 (ADARB1). Recent studies have shown that a critical role of RNA editing is to disrupt double-stranded RNA (dsRNA) structures that are generated by retroelements inserted in the genome in an inverted orientation within expressed genes. The dsRNA formed by such sequence configurations is a powerful and dangerous activator of the ancient antiviral interferon response, which may lead to pathogenic inflammation. While RNA editing has been studied in the context of some organs and in cancer, very little is known about the role of ADAR enzymes in islet cell function and health. Our goal is to elucidate the role of RNA editing in islets, and particularly in alpha and beta cells. Strikingly, GWAS studies of type 1 diabetes (T1D) have revealed protective variants of IFIH1/MDA5, a cytosolic receptor that recognizes double-stranded RNA (dsRNA) from either viral or endogenous origins, and elicits an inflammatory response. Thus, defective RNA editing can in principle contribute to the islet anti-viral response which precedes autoimmunity. We hypothesize that impaired RNA editing and accumulation of endogenous dsRNA in beta cells trigger an IFIH1-dependent interferon response causing islet inflammation, which leads to beta cell dysfunction and potentially to autoimmunity. In our preliminary findings, we found that disruption of A-to-I RNA editing in adult mouse beta-cells in vivo or in human islets triggers an interferon response. In mice with Adar1-deficient beta cells, this leads to massive immune response localized to islets, including both innate immune cells and T cells. Alpha cells appear to resist Adar1 disruption or islet inflammation brought about by Adar1 deficiency in beta cells. We propose to 1) characterize mouse and human islet cells following genetic disruption of RNA editing, via knockout or knockdown of the key RNA editing enzyme Adar1; 2) examine the effects of Adar1 deficiency on beta and alpha cell function and viability, as well as islet inflammation and autoimmunity; and 3) investigate the molecular basis for the differential dependence of alpha and other islet cell types on Adart1. The proposed research is a close collaboration between 3 teams with complementary expertise: Al Powers (human islet biology and function), Yuval Dor (mouse models, molecular biology) and Erez Levanon (computational analysis of RNA editing). This work will shed light on the role of RNA editing, a key epitranscriptomic modification, in islet cells. It will also refute or provide pre-clinical support for the provocative hypothesis that defective RNA editing may contribute to aspects of T1D pathogenesis, particularly the early, anti-viral inflammatory response. 1