ADAR1 Limits RIG-I RNA Detection and Suppresses IFN Production Responding to Viral and Endogenous RNAs

By Shengyong Yang, P. Deng, Zhaowei Zhu, Jianzhong Zhu, Guoliang Wang, Liyong Zhang, Alex F. Chen, Tony Wang, Saumendra N. Sarkar, Timothy R. Billiar and 1 more. 2014

80 citations recorded by the source corpus.

Type I IFNs play central roles in innate immunity; however, overproduction of IFN can lead to immunopathology. In this study, we demonstrate that adenosine deaminase acting on RNA 1 (ADAR1), an RNA-editing enzyme induced by IFN, is essential for cells to avoid inappropriate sensing of cytosolic RNA in an inducible knockout cell model—the primary mouse embryo fibroblast derived from ADAR1 lox/lox and Cre-ER mice as well as in HEK293 cells. ADAR1 suppresses viral and cellular RNA detection by retinoic acid–inducible gene I (RIG-I) through its RNA binding rather than its RNA editing activity. dsRNA binds to both ADAR1 and RIG-I, but ADAR1 reduces RIG-I RNA binding. In the absence of ADAR1, cellular RNA stimulates type I IFN production without viral infection or exogenous RNA stimulation. Moreover, we showed in the ADAR1-inducible knockout mice that ADAR1 gene disruption results in high-level IFN production in neuronal tissues—the hallmark of Aicardi–Goutières syndrome, a heritable autoimmune disease recently found to be associated with ADAR1 gene mutations. In summary, this study found that ADAR1 limits cytosolic RNA sensing by RIG-I through its RNA binding activity; therefore, ADAR1 suppresses type I IFN production stimulated by viral and cellular RNAs. These results explain why loss of ADARA1 causes IFN induction and also indicates a mechanism for the involvement of ADAR1 in autoimmune diseases such as Aicardi–Goutières syndrome.

Subfields: Immunology, Molecular Biology

Citations in the corpus