The University of Osaka · Biochemistry, Genetics and Molecular Biology
Professor Taisuke Nakahama's research lab focuses on the molecular mechanisms underlying immune system regulation, particularly the roles of RNA editing enzymes like ADAR1 and transcriptional regulators such as the aryl hydrocarbon receptor (AHR) in immune cell development and autoimmune diseases. The lab investigates how ADAR1 prevents innate immune activation by editing endogenous dsRNA to avoid MDA5-mediated type I interferon responses, and explores the distinct functions of its p110 and p150 isoforms in thymic development and central tolerance. Additionally, the lab examines how AHR and microRNAs such as the miR-132/212 cluster regulate T helper cell differentiation, especially Th17 and regulatory T cells, in the context of autoimmunity. These studies aim to uncover novel therapeutic targets for autoimmune and inflammatory disorders.
Figures are computed from collected data and may differ slightly.
Aryl hydrocarbon receptor (AHR) plays critical roles in various autoimmune diseases such as multiple sclerosis by controlling interleukin-17 (IL-17)-producing T-helper (TH17) and regulatory T cells. Although various transcription factors and cytokines have been identified as key participants in TH17 generation, the role of microRNAs in this process is poorly understood. In this study, we found that expression of the microRNA (miR)-132/212 cluster is up-regulated by AHR activation under TH17-indu
The contributions of aryl hydrocarbon receptor (Ahr) to the pathogenesis of rheumatoid arthritis have not been elucidated. Here, we show that Ahr deficiency ameliorated collagen-induced arthritis, a mouse model of RA. Collagen-immunized Ahr KO mice showed decreased serum levels of such proinflammatory cytokines as IL-1β and IL-6. The Th17 and Th1 cell populations in lymph nodes from these mice decreased and increased, respectively, whereas the percentage of regulatory T cells was unchanged. Inte
ADAR1 is an RNA-editing enzyme that is abundant in the thymus. We have previously reported that ADAR1 is required for establishing central tolerance during the late stage of thymocyte development by preventing MDA5 sensing of endogenous dsRNA as nonself. However, the role of ADAR1 during the early developmental stage remains unknown. In this study, we demonstrate that early thymocyte-specific deletion of ADAR1 in mice caused severe thymic atrophy with excessive apoptosis and impaired transition
Adenosine deaminase acting on RNA 1 (ADAR1) is an enzyme responsible for double-stranded RNA (dsRNA)-specific adenosine-to-inosine RNA editing, which is estimated to occur at over 100 million sites in humans. ADAR1 is composed of two isoforms transcribed from different promoters: p150 and N-terminal truncated p110. Deletion of ADAR1 p150 in mice activates melanoma differentiation-associated protein 5 (MDA5)-sensing pathway, which recognizes endogenous unedited RNA as non-self. In contrast, we ha
Adenosine deaminase acting on RNA 1 (ADAR1) is an RNA-editing enzyme that catalyzes adenosine-to-inosine conversions in double-stranded RNAs (dsRNAs). In mammals, ADAR1 is composed of two isoforms: a nuclear short p110 isoform and a cytoplasmic long p150 isoform. Whereas both isoforms contain right-handed dsRNA-binding and deaminase domains, ADAR1 p150 harbors a Zα domain that binds to left-handed dsRNAs, termed Z-RNAs. Myeloma differentiation-associated gene 5 (MDA5) sensing of endogenous dsRNA
Adenosine-to-inosine RNA editing is catalyzed by nuclear adenosine deaminase acting on RNA 1 (ADAR1) p110 and ADAR2, and cytoplasmic ADAR1 p150 in mammals, all of which recognize dsRNAs as targets. RNA editing occurs in some coding regions, which alters protein functions by exchanging amino acid sequences, and is therefore physiologically significant. In general, such coding sites are edited by ADAR1 p110 and ADAR2 before splicing, given that the corresponding exon forms a dsRNA structure with a
SUMMARY ADAR1 p150 is an enzyme responsible for adenosine-to-inosine RNA editing. Deletion of ADAR1 p150 results in embryonic lethality with a type I interferon (IFN) signature, caused by aberrant MDA5 sensing unedited transcripts. ADAR1 p150 contains a unique Z-DNA/RNA–binding domain α (Zα); however, the role of this domain remains unknown. A mutation has been identified in this domain in patients with Aicardi-Goutières syndrome (AGS), an inherited interferonopathy, suggesting an essential role
Abstract Adenosine-to-inosine RNA editing is catalyzed by nuclear ADAR1 p110 and ADAR2, and cytoplasmic ADAR1 p150 in mammals, all of which recognize double-stranded RNAs (dsRNAs) as targets. Although its frequency is quite rare, RNA editing occurs in coding regions, which alters protein functions by exchanging amino acid sequences, and is therefore physiologically significant. In general, such coding sites are edited by ADAR1 p110 and ADAR2 prior to splicing, given that the corresponding exon f
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