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Naito S, Tanaka H, Jiang JJ, Tarumi M, Hashimoto A, Tanaka Y, Murakami K, Kubota SI, Hojyo S, Hashimoto S, Murakami M. DDX6 is involved in the pathogenesis of inflammatory diseases via NF-κB activation. Biochem Biophys Res Commun 2024; 703:149666. [PMID: 38377944 DOI: 10.1016/j.bbrc.2024.149666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 02/06/2024] [Accepted: 02/09/2024] [Indexed: 02/22/2024]
Abstract
The IL-6 amplifier was originally discovered as a mechanism for the enhanced activation of NF-κB in non-immune cells. In the IL-6 amplifier, IL-6-STAT3 and NF-κB stimulation is followed by an excessive production of IL-6, chemokines, and growth factors to develop chronic inflammation preceding the development of inflammatory diseases. Previously, using a shRNA-mediated genome-wide screening, we found that DEAD-Box Helicase 6 (DDX6) is a candidate positive regulator of the amplifier. Here, we investigate whether DDX6 is involved in the pathogenesis of inflammatory diseases via the IL-6 amplifier. We found that DDX6-silencing in non-immune cells suppressed the NF-κB pathway and inhibited activation of the IL-6 amplifier, while the forced expression of DDX6 enhanced NF-κB promoter activity independent of the RNA helicase activity of DDX6. The imiquimod-mediated dermatitis model was suppressed by the siRNA-mediated gene downregulation of DDX6. Furthermore, silencing DDX6 significantly reduced the TNF-α-induced phosphorylation of p65/RelA and IκBα, nuclear localization of p65, and the protein levels of IκBα. Mechanistically, DDX6 is strongly associated with p65 and IκBα, but not TRADD, RIP, or TRAF2, suggesting a novel function of DDX6 as an adaptor protein in the NF-κB pathway. Thus, our findings demonstrate a possible role of DDX6 beyond RNA metabolism and suggest DDX6 is a therapeutic target for inflammatory diseases.
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Affiliation(s)
- Seiichiro Naito
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan; Department of Cardiovascular Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hiroki Tanaka
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Jing-Jing Jiang
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Masato Tarumi
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Ari Hashimoto
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yuki Tanaka
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan; Group of Quantum Immunology, Institute for Quantum Life Science, National Institute for Quantum and Radiological Science and Technology (QST), Chiba, Japan
| | - Kaoru Murakami
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Shimpei I Kubota
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Shintaro Hojyo
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Shigeru Hashimoto
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
| | - Masaaki Murakami
- Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan; Group of Quantum Immunology, Institute for Quantum Life Science, National Institute for Quantum and Radiological Science and Technology (QST), Chiba, Japan; Division of Molecular Neuroimmunology, Department of Homeostatic Regulation, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Aichi, Japan; Institute for Vaccine Research and Development (HU-IVReD), Hokkaido University, Sapporo, Japan.
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