Structure‐guided design of immunomodulatory RNAs specifically targeting the cytoplasmic viral RNA sensor RIG‐I

• Published in: FEBS letters 2019-11, Vol.593 (21), p.3003-3014
• Main Authors: Yong, Hui Yee, Zheng, Jie, Ho, Victor Chin Yong, Nguyen, Mai Trinh, Fink, Katja, Griffin, Patrick R., Luo, Dahai
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Cytosine - metabolism; DEAD Box Protein 58 - chemistry; DEAD Box Protein 58 - metabolism; HEK293 Cells; Humans; Immunity, Innate; immunomodulatory RNAs; Protein Binding; Protein Domains; Receptors, Immunologic; RIG‐I; RNA ligands; RNA, Small Interfering - chemistry; RNA, Small Interfering - genetics; RNA, Small Interfering - pharmacology; RNA, Viral - immunology; Signal Transduction; Structure-Activity Relationship
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1002/1873-3468.13564

The cytoplasmic immune sensor RIG‐I detects viral RNA and initiates an antiviral immune response upon activation. It has become a potential target for vaccination and immunotherapies. To develop the smallest but potent immunomodulatory RNA (immRNAs) species, we performed structure‐guided RNA design and used biochemical, structural, and cell‐based methods to select and characterize the immRNAs. We demonstrated that inserting guanosine at position 9 to the 10mer RNA hairpin (3p10LG9) activates RIG‐I more robustly than the parental RNA. 3p10LG9 interacts strongly with the RIG‐I helicase‐CTD RNA sensing module and disrupts the auto‐inhibitory interaction between the HEL2i and CARDs domains. We further showed that 3p10LA9 has a stronger cellular activity than 3p10LG9. Collectively, purine insertion at position 9 of the immRNA species triggered more robust activation of RIG‐1.