RNA editing in islet function and inflammation

RNA编辑是一个基本的细胞过程，涉及到体内某些腺苷的脱氨基 通过腺苷脱氨酶ADAR1(ADAR)和ADAR2(ADARB1)将RNA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)由反向插入基因组的逆转录元件所产生的结构 表达基因内的定位。由这种序列构型形成的dsRNA是 古老的抗病毒干扰素反应的强大而危险的激活剂，这可能导致 致病性炎症。虽然已经在一些器官的背景下研究了RNA编辑 而在癌症中，人们对ADAR酶在胰岛细胞功能和 健康。我们的目标是阐明RNA编辑在胰岛中的作用，特别是在阿尔法和 β细胞。引人注目的是，GWAS对1型糖尿病(T1D)的研究揭示了保护性变异 在IFIH1/MDA5中，一种胞质受体，识别来自 病毒或内源性来源，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编辑和内源性dsRNA积累受损 触发依赖IFIH1的干扰素反应，导致胰岛炎症，从而导致β 细胞功能障碍和潜在的自身免疫。在我们的初步调查结果中，我们发现 体内或人胰岛中成年小鼠β细胞中A-to-I RNA编辑的中断引发了 干扰素反应。在ADAR1缺乏β细胞的小鼠中，这会导致大量免疫 对胰岛的反应，包括先天免疫细胞和T细胞。出现Alpha单元格 以对抗ADAR1破坏或因ADAR1缺乏而导致的胰岛炎症。 我们建议1)描述小鼠和人类的胰岛细胞在RNA基因破坏后的特征 编辑，通过敲除或敲除关键的RNA编辑酶ADAR1；2)检查 ADAR1缺乏对胰岛和胰岛β、α细胞功能和活性的影响 炎症和自身免疫；以及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。拟议的研究是一个结束语。 3个具有互补专业知识的团队之间的合作：Al Power(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 对RNA编辑的分析)。这项工作将阐明RNA编辑的作用，这是一个关键 在胰岛细胞中，表位转录修饰。它还将驳斥或提供临床前支持 有争议的假设认为，有缺陷的RNA编辑可能导致T1D的某些方面 发病机制，尤其是早期、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