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Last Updated :2024/09/03

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Master

Affiliation (Master)

  • Institute for Genetic Medicine　Molecular Pathogenesis

Affiliation (Master)

  • Institute for Genetic Medicine　Molecular Pathogenesis

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Profile and Settings

Profile and Settings

  • Name (Japanese)

    Takaoka

  • Name (Kana)

    Akinori

  • Name

    200901028204742677

Alternate Names

Achievement

Research Areas

  • Life sciences / Immunology
  • Life sciences / Medical biochemistry

Research Experience

  • 2017/10 - Today Hokkaido University Institute for Genetic Medicine
  • 2007/05 - Today Hokkaido University Institute for Genetic Medicine
  • 2012/04 - 2016/03 Hokkaido University Institute for Genetic Medicine
  • 2009/07 - 2012/03 Hokkaido University Institute for Genetic Medicine
  • 2002 - 2007 東京大学医学部免疫学講座 講師
  • 2002 - 2007 Lecturer
  • 2007 - Professor
  • 2000 - 2002 東京大学医学部免疫学講座 助手
  • 2000 - 2002 Research Associate
  • 1997 - 2000 東京大学医学部免疫学講座 日本学術振興会研究員（リサーチ・アソシエイト）
  • 1997 - 2000 Research associate of the Japan Society for the Promotion of Science
  • 1996 - 1997 東京大学医学部免疫学講座 研究員
  • 1996 - 1997 Researcher

Education

  •        - 1996  Sapporo Medical University  Graduate School of Medicine
  •        - 1996  Sapporo Medical University  Graduate School, Division of Medicine
  •        - 1992  Sapporo Medical University  School of Medicine
  •        - 1992  Sapporo Medical University  Faculty of Medicine

Awards

  • 2015/03 北海道大学 研究総長賞（優秀賞）
     
    受賞者: 髙岡 晃教
  • 2014/03 北海道大学 教育総長賞
     
    受賞者: 髙岡 晃教
  • 2013/03 北海道大学 研究総長賞
     
    受賞者: 髙岡 晃教
  • 2011 医学研究奨励賞 (日本医師会:日本)
     
    受賞者: 髙岡 晃教
  • 2005 三菱化学奨励賞 (分子生物学会:日本)
  • 2003 Milstein Young Investigator Award (インターフェロン・サイトカイン学会:オーストラリア）
  • 2003 高松宮妃癌研究基金研究助成国際
  • 2001 奨励賞 (日本癌学会:日本)
  • 2000 Young Investigator Award; 1st prize (国際サイトカイン学会:オランダ)

Published Papers

  • Hiraku Suzuki, Yuki Fujiwara, Winda Ariyani, Izuki Amano, Sumiyasu Ishii, Ayane Kate Ninomiya, Seiichi Sato, Akinori Takaoka, Noriyuki Koibuchi
    International Journal of Molecular Sciences 2024/04/26 [Refereed]
  • Nabeel Kajihara, Yoshino Tanaka, Riko Takeuchi, Takuto Kobayashi, Masafumi Tanji, Tsukasa Ataka, Shiho Nakano, Taisho Yamada, Akinori Takaoka, Yoshinori Hasegawa, Ken-Ichiro Seino, Haruka Wada
    OncoImmunology 12 (1) 2023/05/22
  • Taisho Yamada, Akinori Takaoka
    Inflammation and Regeneration 43 (1) 2023/01/26 
    Abstract Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative virus of pandemic acute respiratory disease called coronavirus disease 2019 (COVID-19). Most of the infected individuals have asymptomatic or mild symptoms, but some patients show severe and critical systemic inflammation including tissue damage and multi-organ failures. Immune responses to the pathogen determine clinical course. In general, the activation of innate immune responses is mediated by host pattern-recognition receptors (PRRs) that recognize pathogen-associated molecular patterns (PAMPs) as well as host damage-associated molecular patterns (DAMPs), which results in the activation of the downstream gene induction programs of types I and III interferons (IFNs) and proinflammatory cytokines for inducing antiviral activity. However, the excessive activation of these responses may lead to deleterious inflammation. Here, we review the recent advances in our understanding of innate immune responses to SARS-CoV-2 infection, particularly in terms of innate recognition and the subsequent inflammation underlying COVID-19 immunopathology.
  • Akhilesh Kumar, Shalabh Mishra, Ashish Kumar, Ashwin Ashok Raut, Seiichi Sato, Akinori Takaoka, Himanshu Kumar
    Cell death & disease 13 (6) 520 - 520 2022/06/02 
    Intracellular and cell surface pattern-recognition receptors (PRRs) are an essential part of innate immune recognition and host defense. Here, we have compared the innate immune responses between humans and bats to identify a novel membrane-associated protein, Rnd1, which defends against viral and bacterial infection in an interferon-independent manner. Rnd1 belongs to the Rho GTPase family, but unlike other small GTPase members, it is constitutively active. We show that Rnd1 is induced by pro-inflammatory cytokines during viral and bacterial infections and provides protection against these pathogens through two distinct mechanisms. Rnd1 counteracts intracellular calcium fluctuations by inhibiting RhoA activation, thereby inhibiting virus internalisation. On the other hand, Rnd1 also facilitates pro-inflammatory cytokines IL-6 and TNF-α through Plxnb1, which are highly effective against intracellular bacterial infections. These data provide a novel Rnd1-mediated innate defense against viral and bacterial infections.
  • Shin Hashizume, Masako Nakano, Kenta Kubota, Seiichi Sato, Nobuaki Himuro, Eiji Kobayashi, Akinori Takaoka, Mineko Fujimiya
    Scientific Reports 11 (1) 21848 - 21848 2021/12 [Refereed]
     
    AbstractAlthough mindfulness-based stress reduction (MBSR) improves cognitive function, the mechanism is not clear. In this study, people aged 65 years and older were recruited from elderly communities in Chitose City, Japan, and assigned to a non-MBSR group or a MBSR group. Before and after the intervention, the Japanese version of the Montreal Cognitive Assessment (MoCA-J) was administered, and blood samples were collected. Then, neuron-derived extracellular vesicles (NDEVs) were isolated from blood samples, and microRNAs, as well as the target mRNAs, were evaluated in NDEVs. A linear mixed model analysis showed significant effects of the MBSR x time interaction on the MoCA-J scores, the expression of miRNA(miR)-29c, DNA methyltransferase 3 alpha (DNMT3A), and DNMT3B in NDEVs. These results indicate that MBSR can improve cognitive function by increasing the expression of miR-29c and decreasing the expression of DNMT3A, as well as DNMT3B, in neurons. It was also found that intracerebroventricular injection of miR-29c mimic into 5xFAD mice prevented cognitive decline, as well as neuronal loss in the subiculum area, by down-regulating Dnmt3a  and Dnmt3b  in the hippocampus. The present study suggests that MBSR can prevent neuronal loss and cognitive impairment by increasing the neuronal expression of miR-29c.
  • Sunanda Baidya, Yoko Nishimoto, Seiichi Sato, Yasuhiro Shimada, Nozomi Sakurai, Hirotaka Nonaka, Koki Noguchi, Mizuki Kido, Satoshi Tadano, Kozo Ishikawa, Kai Li, Aoi Okubo, Taisho Yamada, Yasuko Orba, Michihito Sasaki, Hirofumi Sawa, Hiroko Miyamoto, Ayato Takada, Takashi Nakamura, Akinori Takaoka
    Viruses 13 (9) 1674 - 1674 2021/08/24 
    The interaction of viral nucleic acid with protein factors is a crucial process for initiating viral polymerase-mediated viral genome replication while activating pattern recognition receptor (PRR)-mediated innate immune responses. It has previously been reported that a hydrolysate of Ge-132, 3-(trihydroxygermyl) propanoic acid (THGP), shows a modulatory effect on microbial infections, inflammation, and immune responses. However, the detailed mechanism by which THGP can modify these processes during viral infections remained unknown. Here, we show that THGP can specifically downregulate type I interferon (IFN) production in response to stimulation with a cytosolic RNA sensor RIG-I ligand 5′-triphosphate RNA (3pRNA) but not double-stranded RNA, DNA, or lipopolysaccharide. Consistently, treatment with THGP resulted in the dose-dependent suppression of type I IFN induction upon infections with influenza virus (IAV) and vesicular stomatitis virus, which are known to be mainly sensed by RIG-I. Mechanistically, THGP directly binds to the 5′-triphosphate moiety of viral RNA and competes with RIG-I-mediated recognition. Furthermore, we found that THGP can directly counteract the replication of IAV but not EMCV (encephalitismyocarditis virus), by inhibiting the interaction of viral polymerase with RNA genome. Finally, IAV RNA levels were significantly reduced in the lung tissues of THGP-treated mice when compared with untreated mice. These results suggest a possible therapeutic implication of THGP and show direct antiviral action, together with the suppressive activity of innate inflammation.
  • Taisho Yamada, Seiichi Sato, Yuki Sotoyama, Yasuko Orba, Hirofumi Sawa, Hajime Yamauchi, Michihito Sasaki, Akinori Takaoka
    Nature Immunology 22 (7) 820 - 828 1529-2908 2021/07
  • Akinori Takaoka, Seiichi Sato, Taisho Yamada
    Handbook of Hormones 435 - 435 2021
  • Seiichi Sato, Akinori Takaoka
    Handbook of Hormones 437 - 439 2021
  • Seiichi Sato, Kai Li, Nozomi Sakurai, Mei Hashizume, Sunanda Baidya, Hirotaka Nonaka, Koki Noguchi, Kozo Ishikawa, Chikashi Obuse, Akinori Takaoka
    Cellular immunology 356 104188 - 104188 2020/07/28 [Refereed][Not invited]
     
    Stimulator of interferon genes (STING) plays important roles in the DNA-mediated innate immune responses. However, the regulatory mechanism of STING in terms of stabilization is not fully understood. Here, we identified the chaperone protein Hsp90s as novel STING interacting proteins. Treatment with an Hsp90 inhibitor 17-AAG and knockdown of Hsp90β but not Hsp90α reduced STING at protein level, resulted in the suppression of IFN induction in response to stimulation with cGAMP, and infections with HSV-1 and Listeria monocytogenes. Collectively, our results suggest that the control of STING protein by Hsp90β is a critical biological process in the DNA sensing pathways.
  • Mitsuo Maruyama, Akihiko Sakamoto, Yuji Morita, Akinori Takaoka
    Yakugaku Zasshi 140 (3) 391 - 393 1347-5231 2020/03/01 
    Recently, aging is becoming an important social problem in many developed countries including Japan. It is socially and universally important to unveil the impact of aging and extend healthy life expectancy. Here we show our recent finding that dedicator of cytokinesis 11 (DOCK11, also known as Zizimin2) may be involved in immunosenescence of B cells. DOCK11 was identified as a guanine nucleotide exchange factor for a small GTPase called cell division cycle 42. Expression of DOCK11 is restricted to lymphoid tissues, and becomes downregulated with age. Thus we examined the involvement of DOCK11 in immunosenescence of B-1a B cells as an example. B-1a cells are the main source of antibodies at steady state, and function as the first line of defense against infection. Although DOCK11 was expressed by B-1a cells, the expression levels declined with age. Furthermore, production of anti-pneumococcal immunoglobulin M antibodies was suppressed in aged mice, and was recovered by adoptive transfer with B-1a cells in a DOCK11-dependent manner. Thus DOCK11 may be involved in immunosenescence of B-1a cells.
  • Mei Hashizume, Koki Aoki, Shigeaki Ohno, Nobuyoshi Kitaichi, Nobuyo Yawata, Gabriel Gonzalez, Hirotaka Nonaka, Seiichi Sato, Akinori Takaoka
    European journal of ophthalmology 31 (2) 1120672119891408 - 1120672119891408 1120-6721 2019/12/09 [Refereed][Not invited]
     
    PURPOSE: The aim of this study was to test the antiviral effectivity of potassium peroxymonosulfate (RUBYSTA®, KYORIN) against five epidemic keratoconjunctivitis-related types of Human adenovirus D in vitro. METHODS: Five types of Human adenovirus D (8, 37, 53, 54 and 56) were incubated with 1% potassium peroxymonosulfate, 0.1% sodium hypochlorite (NaClO) or alcohol-based disinfectant for 30 s or 1 min. These solutions were subjected to measurements of viral titres by infection assays in A549 cells. At day 6 post-infection, both, supernatants and cells, were collected and the viral genome was assessed by real-time polymerase chain reaction analysis. RESULTS: Treatments with 1% potassium peroxymonosulfate led to significant reduction in all tested Human adenovirus D types comparable to disinfecting effects by 0.1% NaClO. Overall, potassium peroxymonosulfate demonstrated sufficient inactivation of the major epidemic keratoconjunctivitis-causing Human adenovirus D to be considered for disinfection and prevention purposes in ophthalmological clinics and hospitals. CONCLUSION: This study demonstrated that potassium peroxymonosulfate is a promising disinfectant for the prevention of epidemic keratoconjunctivitis nosocomial infections in ophthalmological clinics.
  • Suzuki H, Kameyama T, Takaoka A
    Biochem Biophys Res Commun 511 (2) 287 - 293 2019/04 [Not refereed][Not invited]
  • Takaoka A, Yamada T
    Int Immunol 15 dxz034  2019/04 [Not refereed][Not invited]
  • Hamada-Tsutsumi S, Naito Y, Sato S, Takaoka A, Kawashima K, Isogawa M, Ochiya T, Tanaka Y
    Aliment Pharmacol Ther 49 (8) 1060 - 1070 2019/04 [Not refereed][Not invited]
     
    BACKGROUND: Conventional treatments of chronic hepatitis B virus (HBV) infection rarely achieve a decline of serum hepatitis B surface antigen (HBsAg) levels and eradication of the virus. AIM: To elucidate the antiviral mechanisms of a human microRNA, miR-302c-3p, against HBV replication. METHODS: The antiviral effect of miR-302c-3p was evaluated in vitro and in vivo by transfecting the miR-302c-3p mimic into HBV-infected HepG2-hNTCP-C4 cells and HBV transgenic mice respectively. RESULTS: miR-302c-3p decreased not only HBV replication but also production of HBsAg. Pregenomic RNA and HBsAg mRNA concentrations decreased in the cells treated with miR-302c-3p. Interestingly, the amount of cccDNA was significantly reduced in the miR-302c-3p-treated cells, in association with disappearance of the HBV core protein. An RNA immunoprecipitation assay showed that miR-302c-3p decreased the binding of the HBV polymerase to the pregenomic RNA by hybridising with the ε-loop region. A number of host genes were downregulated in miR-302c-3p-treated cells, including BMPR2 and HNF4A. Knockdown of these two genes by corresponding siRNAs also suppressed HBV replication and HBsAg secretion. The antiviral effect of miR-302c-3p was also observed in HBV transgenic mice. CONCLUSION: miR-302c-3p had anti-HBV activity, in vitro and in vivo, via several mechanisms.
  • Kumar A, Kumar A, Ingle H, Kumar S, Mishra R, Verma MK, Biswas D, Kumar NS, Mishra A, Raut AA, Takaoka A, Kumar H
    J Virol. 92 (19) e01057  2018/09 [Not refereed][Not invited]
  • Takaoka A
    Nat Immunol. 19 (3) 207 - 208 2018/03 [Not refereed][Not invited]
  • Daisuke Muramatsu, Mitsuyasu Okabe, Akinori Takaoka, Hiroshi Kida, Atsushi Iwai
    Scientific Reports 7 (1) 2831  2045-2322 2017/12/01 [Not refereed][Not invited]
     
    Black yeast, Aureobasidium pullulans is extracellularly produced β-(1,3), (1,6)-D-glucan (β-glucan) under certain conditions. In this study, using Glycine max cv. Kurosengoku (Kurosengoku soybeans), the production of β-glucan through fermentation of A. pullulans was evaluated, and the effects of A. pullulans cultured fluid (AP-CF) containing β-glucan made with Kurosengoku soybeans (kAP-CF) on a human monocyte derived cell line, Mono Mac 6 cells were investigated. Concentration of β-glucan in kAP-CF reached the same level as normal AP-CF. An anti-angiogenic protein, Thrombospondin-1 (THBS1) was effectively induced after the stimulation with kAP-CF for comparison with AP-CF. The THBS1 is also induced after stimulation with hot water extract of Kurosengoku soybeans (KS-E), while the combined stimulation of β-glucan with KS-E more effectively induced THBS1 than that with KS-E alone. These results suggest effects of A. pullulans-produced β-glucan on the enhancement of Kurosengoku soybean-induced THBS1 expression.
  • Puja Kumari, Irene Saha, Athira Narayanan, Sathish Narayanan, Akinori Takaoka, Nachimuthu Senthil Kumar, Prafullakumar Tailor, Himanshu Kumar
    CELL DEATH & DISEASE 8 (10) e3078  2041-4889 2017/10 [Refereed][Not invited]
     
    Cancer is a multifactorial disease and virus-mediated carcinogenesis is one of the crucial factors, which is poorly understood. Human cytomegalovirus (HCMV) is a herpesvirus and its components have been evidenced to be associated with cancer of different tissue origin. However, its role in cancer remains unknown. Here, we identified a conserved herpesviral tegument protein known as pUL48 of HCMV, encoding deubiquitinase enzyme, as having a key role in carcinogenesis. We show using deubiquitinase sufficient-and deficient-HCMV that HCMV deubiquitinase is a key in inducing enhanced cellular metabolic activity through upregulation of several anti-apoptotic genes and downregulation of several pro-apoptotic genes expression. Furthermore, HCMV deubiquitinase acquires pro-tumor functions by inhibiting PRR-mediated type I interferon via deubiquitination of TRAF6, TRAF3, IRAK1, IRF7 and STING. Taken together, our results suggest that HCMV infection may promote oncogenesis by inhibiting innate immunity of the host.
  • Akihiko Sakamoto, Takenori Matsuda, Koichiro Kawaguchi, Akinori Takaoka, Mitsuo Maruyama
    International Immunology 29 (9) 431 - 438 1460-2377 2017 [Refereed][Not invited]
     
    Zizimin2 (Ziz2), also known as dedicator of cytokinesis 11 (DOCK11), is a guanine nucleotide exchange factor that is predominantly expressed in lymphoid tissues. Recent findings demonstrated that Ziz2 is involved in the development of B cells, including germinal centre B cells and marginal zone B cells. However, limited information is currently available on the roles of Ziz2 in B-1 cells, a B-cell subset that resides in body cavities and contributes to protection against foreign pathogens in a T-cell-independent manner. We herein show that Ziz2 and its widely expressed isoform Ziz3 (also known as DOCK10) may be involved in defective production of anti-bacterial IgM by aged B-1a cells, a CD5+ subset of B-1 cells. Natural IgM against typical bacterial epitopes was defectively produced by peritoneal B-1a cells from aged mice. The down-regulation of Ziz2/3 in B-1a cells appeared to be responsible for this defective IgM production, as demonstrated by Ziz2/3 double-knockout mice. Mechanistically, lower levels of basal AKT phosphorylation did not allow for the differentiation of Ziz2/3-deficient B-1a cells into plasma cells. Defective production of anti-bacterial IgM was not fully rescued by immunization, resulting in slightly weaker protection in Ziz2/3-deficient mice. Thus, the down-regulation of Ziz2/3 in B-1a cells may at least partly account for defective protection in aged mice.
  • Melody M. H. Li, Zerlina Lau, Pamela Cheung, Eduardo G. Aguilar, William M. Schneider, Leonia Bozzacco, Henrik Molina, Eugen Buehler, Akinori Takaoka, Charles M. Rice, Dan P. Felsenfeld, Margaret R. MacDonald
    PLOS PATHOGENS 13 (1) e1006145  1553-7366 2017/01 [Refereed][Not invited]
     
    The host factor and interferon (IFN)-stimulated gene (ISG) product, zinc-finger antiviral protein (ZAP), inhibits a number of diverse viruses by usurping and intersecting with multiple cellular pathways. To elucidate its antiviral mechanism, we perform a loss-of-function genome-wide RNAi screen to identify cellular cofactors required for ZAP antiviral activity against the prototype alphavirus, Sindbis virus (SINV). In order to exclude off-target effects, we carry out stringent confirmatory assays to verify the top hits. Important ZAP-liaising partners identified include proteins involved in membrane ion permeability, type I IFN signaling, and post-translational protein modification. The factor contributing most to the antiviral function of ZAP is TRIM25, an E3 ubiquitin and ISG15 ligase. We demonstrate here that TRIM25 interacts with ZAP through the SPRY domain, and TRIM25 mutants lacking the RING or coiled coil domain fail to stimulate ZAP's antiviral activity, suggesting that both TRIM25 ligase activity and its ability to form oligomers are critical for its cofactor function. TRIM25 increases the modification of both the short and long ZAP isoforms by K48-and K63-linked polyubiquitin, although ubiquitination of ZAP does not directly affect its antiviral activity. However, TRIM25 is critical for ZAP's ability to inhibit translation of the incoming SINV genome. Taken together, these data uncover TRIM25 as a bona fide ZAP cofactor that leads to increased ZAP modification enhancing its translational inhibition activity.
  • Taisho Yamada, Hiromasa Horimoto, Takeshi Kameyama, Sumio Hayakawa, Hiroaki Yamato, Masayoshi Dazai, Ayato Takada, Hiroshi Kida, Debbie Bott, Angela C. Zhou, David Hutin, Tania H. Watts, Masahiro Asaka, Jason Matthews, Akinori Takaoka
    NATURE IMMUNOLOGY 17 (6) 687 - + 1529-2908 2016/06 [Refereed][Not invited]
     
    Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that mediates the toxic activity of many environmental xenobiotics. However, its role in innate immune responses during viral infection is not fully understood. Here we demonstrate that constitutive AHR signaling negatively regulates the type I interferon (IFN-I) response during infection with various types of virus. Virus-induced IFN-beta production was enhanced in AHR-deficient cells and mice and resulted in restricted viral replication. We found that AHR upregulates expression of the ADP-ribosylase TIPARP, which in turn causes downregulation of the IFN-I response. Mechanistically, TIPARP interacted with the kinase TBK1 and suppressed its activity by ADP-ribosylation. Thus, this study reveals the physiological importance of endogenous activation of AHR signaling in shaping the IFN-I-mediated innate response and, further, suggests that the AHR-TIPARP axis is a potential therapeutic target for enhancing antiviral responses.
  • Shoichiro Kameoka, Takeshi Kameyama, Takaya Hayashi, Seiichi Sato, Naomi Ohnishi, Takeru Hayashi, Naoko Murata-Kamiya, Hideaki Higashi, Masanori Hatakeyama, Akinori Takaoka
    BIOMEDICAL RESEARCH-TOKYO 37 (1) 21 - 27 0388-6107 2016 [Refereed][Not invited]
     
    More than 50% of people in the world are infected with Helicobacter pylori (H. pylori), which induces various gastric diseases. Especially, epidemiological studies have shown that H. pylori infection is a major risk factor for gastric cancer. It has been reported that the levels of interleukin (IL)-1 beta are upregulated in gastric tissues of patients with H. pylori infection. In this study, we investigated the induction mechanism of IL-1 beta during H. pylori infection. We found that IL-1 beta mRNA and protein were induced in phorbol-12-myristate-13-acetate (PMA)-differentiated THP-1 cells after H. pylori infection. This IL-1 beta production was inhibited by a caspase-1 inhibitor and a ROS inhibitor. Furthermore, K+ efflux and Ca2+ signaling were also involved in this process. These data suggest that NOD-like receptor (NLR) family, pyrin domain containing 3 (NLRP3) and its complex, known as NLRP3 inflammasome, are involved in IL-1 beta production during H. pylori infection because it is reported that NLRP3 inflammasome is activated by ROS, K+ efflux and/or Ca2+ signaling. These findings may provide therapeutic strategy for the control of gastric cancer in H. pylori-infected patients.
  • Akinori Takaoka, Amiko Masuya, Naoya Katsuyama
    Seikagaku 88 (3) 419 - 424 2189-0544 2016 [Not refereed][Not invited]
  • Harshad Ingle, Sushil Kumar, Ashwin Ashok Raut, Anamika Mishra, Diwakar Dattatraya Kulkarni, Takeshi Kameyama, Akinori Takaoka, Shizuo Akira, Himanshu Kumar
    Science Signaling 8 (406) ra126  1937-9145 2015/12/08 [Refereed][Not invited]
     
    MicroRNAs (miRNAs) are small noncoding RNAs that are responsible for dynamic changes in gene expression, and some regulate innate antiviral responses. Retinoic acid-inducible gene I (RIG-I) is a cytosolic sensor of viralRNA RIG-I activation induces an antiviral immune response.Wefound that miR-485 of the hostwas produced in response to viral infection and targeted RIG-ImRNAfor degradation,which led to suppression of the antiviral response and enhanced viral replication. Thus, inhibition of the expression of mir-485 markedly reduced the replication of Newcastle disease virus (NDV) and the H5N1 strain of influenza virus in mammalian cells. Unexpectedly, miR-485 also bound to the H5N1 gene PB1 (which encodes an RNA polymerase required for viral replication) in a sequence-specificmanner, thereby inhibiting replication of the H5N1 virus. Furthermore,miR-485 exhibited bispecificity, targeting RIG-I in cells with a low abundance of H5N1 virus and targeting PB1 in cells with increased amounts of the H5N1 virus. These findings highlight the dual role of miR-485 in preventing spurious activation of antiviral signaling and restricting influenza virus infection.
  • Anannya Bhattacharya, Ahmed N. Hegazy, Nikolaus Deigendesch, Lindsay Kosack, Jovana Cupovic, Richard K. Kandasamy, Andrea Hildebrandt, Doron Merkler, Anja A. Kuehl, Bojan Vilagos, Christopher Schliehe, Isabel Panse, Kseniya Khamina, Hatoon Baazim, Isabelle Arnold, Lukas Flatz, Haifeng C. Xu, Philipp A. Lang, Alan Aderem, Akinori Takaoka, Giulio Superti-Furga, Jacques Colinge, Burkhard Ludewig, Max Loehning, Andreas Bergthaler
    IMMUNITY 43 (5) 974 - 986 1074-7613 2015/11 [Refereed][Not invited]
     
    Tissue damage caused by viral hepatitis is a major cause of morbidity and mortality worldwide. Using a mouse model of viral hepatitis, we identified virus-induced early transcriptional changes in the redox pathways in the liver, including downregulation of superoxide dismutase 1 (Sod1). Sod1(-/-) mice exhibited increased inflammation and aggravated liver damage upon viral infection, which was independent of T and NK cells and could be ameliorated by antioxidant treatment. Type I interferon (IFN-I) led to a downregulation of Sod1 and caused oxidative liver damage in Sod1(-/-) and wild-type mice. Genetic and pharmacological ablation of the IFN-I signaling pathway protected against virus-induced liver damage. These results delineate IFN-I mediated oxidative stress as a key mediator of virus-induced liver damage and describe a mechanism of innate-immunity-driven pathology, linking IFN-I signaling with antioxidant host defense and infection-associated tissue damage.
  • S. Kumar, H. Ingle, S. Mishra, R. S. Mahla, A. Kumar, T. Kawai, S. Akira, A. Takaoka, A. A. Raut, H. Kumar
    Cell Death and Disease 6 (5) e1758  2041-4889 2015/05/01 [Refereed][Not invited]
     
    RIG-I-like receptors are the key cytosolic sensors for RNA viruses and induce the production of type I interferons (IFN) and proinflammatory cytokines through a sole adaptor IFN-β promoter stimulator-1 (IPS-1) (also known as Cardif, MAVS and VISA) in antiviral innate immunity. These sensors also have a pivotal role in anticancer activity through induction of apoptosis. However, the mechanism for their anticancer activity is poorly understood. Here, we show that anticancer vaccine adjuvant, PolyIC (primarily sensed by MDA5) and the oncolytic virus, Newcastle disease virus (NDV) (sensed by RIG-I), induce anticancer activity. The ectopic expression of IPS-1 into type I IFN-responsive and non-responsive cancer cells induces anticancer activity. PolyIC transfection and NDV infection upregulate pro-apoptotic gene TRAIL and downregulate the anti-apoptotic genes BCL2, BIRC3 and PRKCE. Furthermore, stable knockdown of IPS-1, IRF3 or IRF7 in IFN-non-responsive cancer cells show reduced anticancer activity by suppressing apoptosis via TRAIL and anti-apoptotic genes. Collectively, our study shows that IPS-1 induces anticancer activity through upregulation of pro-apoptotic gene TRAIL and downregulation of the anti-apoptotic genes BCL2, BIRC3 and PRKCE via IRF3 and IRF7 in type I IFN-dependent and -independent manners.
  • Koji Kawata, Atsushi Iwai, Daisuke Muramatsu, Shiho Aoki, Hirofumi Uchiyama, Mitsuyasu Okabe, Sumio Hayakawa, Akinori Takaoka, Tadaaki Miyazaki
    PLOS ONE 10 (4) e0124809  1932-6203 2015/04 [Refereed][Not invited]
     
    A beta-glucan produced by Aureobasidium pullulans (AP-PG) is consisting of a beta-(1,3)-linked main chain with beta-(1,6)-linked glucose side residues. Various beta-glucans consisting of beta-(1,3)-linked main chain including AP-PG are believed to exhibit anti-tumor activities, and actually, anti-tumor activities of AP-PG in mice have been demonstrated. In this study, we demonstrate that stimulation with AP-PG induces TRAIL expression in mouse and human macrophage-like cell lines. TRAIL is known to be a cytokine which specifically induces apoptosis in transformed cells, but not in untransformed cells. The expression of TRAIL mRNA after stimulation with AP-PG was increased in RAW264.7 cells, Mono Mac 6 cells, and macrophage-differentiated THP-1 cells. The mRNA expression of TNF-alpha and FasL is only weakly increased after stimulation with AP-PG. The induction activity of TRAIL by curdlan, a bacterial beta-glucan, was very similar to that by AP-PG in RAW264.7 cells, but weaker in macrophage-differentiated THP-1 cells. Activation of caspases was found in HeLa cells after treatment with the supernatant of cultured medium from AP-PG-stimulated Mono Mac 6 cells, and was inhibited by the anti-TRAIL neutralizing antibody. These findings suggest that the stimulation with AP-PG effectively induces TRAIL in macrophages, and that it may be related to apoptosis induction of tumor cells.
  • Takenori Matsuda, Shougo Yanase, Akinori Takaoka, Mitsuo Maruyama
    IMMUNITY & AGEING 12 (1) 1742-4933 2015/02 [Refereed][Not invited]
     
    We originally cloned and identified murine Zizimin2 (Ziz2, Dock11) as a guanine nucleotide exchange factor (GEF) for Cdc42 and demonstrated that it activated the formation of filopodia. Since its expression pattern is restricted in immune tissues and Rho GTPases such as Cdc42 function in B cell development and immune responses, we expected Ziz2 to also be associated with B cell development and immune responses. However, the function of Ziz2 has not yet been fully examined in vivo. We also recently discovered that Ziz2 expression levels in immune tissues were reduced with aging in the mouse, suggesting that its expression is also associated with the mechanisms of immuno-senescence. To gain insights into the mechanisms underlying immuno-senescence, we generated Ziz2 knock out (KO) mice and examined the functions of Ziz2 in B cell development and immune responses. We also obtained Zizimin3 (Ziz3; Dock10) KO mice and examined the functions of Ziz3. The results revealed that Ziz2 KO mice had a higher percentage of early bone marrow B cells (Fraction A), but a reduced fraction of marginal zone (MZ) B cells. In addition, an examination of B cell-specific Ziz2 KO mice revealed that Ziz2 was intrinsically required for MZ B cell development, but not for mature follicular B cells. However, immune responses against NP-CGG (T cell-dependent), TNP-LPS (T cell-independent, TI, type I), and TNP-Ficoll (TI, type II) were not altered in KO mice. We finally demonstrated that CD1d-positive MZ B cell region outside CD169-positive marginal metallophilic macrophages (MMM) was narrowed in Ziz2 KO mice. Furthermore, MMM morphology appeared to be altered in Ziz2 KO mice. In conclusion, we herein showed that Ziz2 was associated with early bone marrow B cell development, MZ B cell formation, MZ B number/localization around MZ, and MMM morphology which may explain in part the mechanism underlying immuno-senescence.
  • Seiichi Sato, Kai Li, Takeshi Kameyama, Takaya Hayashi, Yuji Ishida, Shuko Murakami, Tsunamasa Watanabe, Sayuki Iijima, Yu Sakurai, Koichi Watashi, Susumu Tsutsumi, Yusuke Sato, Hidetaka Akita, Takaji Wakita, Charles M. Rice, Hideyoshi Harashima, Michinori Kohara, Yasuhito Tanaka, Akinori Takaoka
    IMMUNITY 42 (1) 123 - 132 1074-7613 2015/01 [Refereed][Not invited]
     
    Host innate recognition triggers key immune responses for viral elimination. The sensing mechanism of hepatitis B virus (HBV), a DNA virus, and the subsequent downstream signaling events remain to be fully clarified. Here we found that type III but not type I interferons are predominantly induced in human primary hepatocytes in response to HBV infection, through retinoic acid-inducible gene-I (RIG-I)-mediated sensing of the 5'-epsilon region of HBV pregenomic RNA. In addition, RIG-I could also counteract the interaction of HBV polymerase (P protein) with the 5'-epsilon region in an RNA-binding dependent manner, which consistently suppressed viral replication. Liposome-mediated delivery and vector-based expression of this e region-derived RNA in liver abolished the HBV replication in human hepatocyte-chimeric mice. These findings identify an innate-recognition mechanism by which RIG-I dually functions as an HBV sensor activating innate signaling and to counteract viral polymerase in human hepatocytes.
  • Daichi Ota, Masashi Kanayama, Yutaka Matsui, Koyu Ito, Naoyoshi Maeda, Goro Kutomi, Koichi Hirata, Toshihiko Torigoe, Noriyuki Sato, Akinori Takaoka, Ann F Chambers, Junko Morimoto, Toshimitsu Uede
    Journal of molecular medicine (Berlin, Germany) 92 (12) 1271 - 81 0946-2716 2014/12 [Refereed][Not invited]
     
    UNLABELLED: Tumor-derived matricellular proteins such as osteopontin (OPN) and tenascin-C (TN-C) have been implicated in tumor growth and metastasis. However, the molecular basis of how these proteins contribute to tumor progression remains to be elucidated. Importantly, these matricellular proteins are known to interact with α9β1 integrin. Therefore, we hypothesized that tumor-derived α9β1 integrin may contribute to tumor progression. To clarify the roles of α9β1 integrin in tumor growth and lymphatic metastasis, we used an inhibitory anti-human α9β1 integrin antibody (anti-hα9β1 antibody) and a α9β1 integrin-positive human breast cancer cell line, MDA-MB-231 luc-D3H2LN (D3H2LN), in vitro functional assays, and an in vivo orthotopic xenotransplantation model. In this study, we demonstrated that tumor, but not host α9β1 integrin, contributes to tumor growth, lymphatic metastasis, recruitment of cancer-associated fibroblasts (CAFs), and host-derived OPN production. We also found that CAFs contributed to tumor growth, lymphatic metastasis, and host-derived OPN levels. Consistent with those findings, tumor volume was well-correlated with numbers of CAFs and levels of host-derived OPN. Furthermore, it was shown that the inoculation of D3H2LN cells into mammary fat pads with mouse embryonic fibroblasts (MEFs), obtained from wild type, but not OPN knock-out mice, resulted in enhancement of tumor growth, thus indicating that CAF-derived OPN enhanced tumor growth. These results suggested that tumor α9β1-mediated signaling plays a pivotal role in generating unique primary tumor tissue microenvironments, which favor lymphatic metastasis and tumor growth. KEY MESSAGES: Tumor α9β1 integrin promotes lymphatic metastasis through enhancing invasion. Tumor α9β1 integrin promotes tumor growth through CAFs. Tumor α9β1 integrin enhances the recruitment of CAFs into the primary tumor. Tumor cells induce the production of OPN by CAFs in the primary tumor. CAF-derived OPN promotes tumor growth.
  • Koyu Ito, Junko Morimoto, Akio Kihara, Yutaka Matsui, Daisuke Kurotaki, Masashi Kanayama, Szandor Simmons, Masaru Ishii, Dean Sheppard, Akinori Takaoka, Toshimitsu Uede
    Proceedings of the National Academy of Sciences of the United States of America 111 (8) 3080 - 5 2014/02/25 [Refereed][Not invited]
     
    Sphingosine 1-phosphate (S1P) plays a role in lymphocyte egress from lymphoid organs. However, it remains unclear how S1P production and secretion are regulated. We show that under inflammatory conditions, α9 integrin, which is closely associated with activated β1 integrin, and its ligand, tenascin-C, colocalize on medullary and cortical sinuses of draining lymph nodes (dLNs), which is a gate for lymphocyte exit, and that inhibition of lymphocyte egress is evident by blockade of α9 integrin-mediated signaling at dLNs. Based on in vitro analysis using lymphatic endothelial cells obtained from mice embryos, we suggested the possibility that stimulation of lymphatic endothelial cells by tenascin-C enhances S1P secretion in an α9 integrin-dependent manner without affecting S1P synthesis and/or degradation. Blockade of α9 integrin-mediated signaling reduced lymphocyte egress from dLNs in several models, including experimental autoimmune encephalomyelitis, where it improved clinical scores and pathology. Therefore, manipulating α9 integrin function may offer a therapeutic strategy for treating various inflammatory disorders.
  • Kameyama T, Takaoka A
    Methods in molecular biology (Clifton, N.J.) 1142 19 - 32 1064-3745 2014 [Refereed][Not invited]
  • Shin-ichiro Nakagawa, Yuichi Hirata, Takeshi Kameyama, Yuko Tokunaga, Yasumasa Nishito, Kazuko Hirabayashi, Junichi Yano, Takahiro Ochiya, Chise Tateno, Yasuhito Tanaka, Masashi Mizokami, Kyoko Tsukiyama-Kohara, Kazuaki Inoue, Makoto Yoshiba, Akinori Takaoka, Michinori Kohara
    PLOS ONE 8 (3) e59611.  1932-6203 2013/03 [Refereed][Not invited]
     
    Background & Aims: The interferon (IFN) system plays a critical role in innate antiviral response. We presume that targeted induction of IFN in human liver shows robust antiviral effects on hepatitis C virus (HCV) and hepatitis B virus (HBV). Methods: This study used chimeric mice harboring humanized livers and infected with HCV or HBV. This mouse model permitted simultaneous analysis of immune responses by human and mouse hepatocytes in the same liver and exploration of the mechanism of antiviral effect against these viruses. Targeted expression of IFN was induced by treating the animals with a complex comprising a hepatotropic cationic liposome and a synthetic double-stranded RNA analog, pIC (LIC-pIC). Viral replication, IFN gene expression, IFN protein production, and IFN antiviral activity were analyzed (for type I, II and III IFNs) in the livers and sera of these humanized chimeric mice. Results: Following treatment with LIC-pIC, the humanized livers of chimeric mice exhibited increased expression (at the mRNA and protein level) of human IFN-lambda s, resulting in strong antiviral effect on HBV and HCV. Similar increases were not seen for human IFN-alpha or IFN-beta in these animals. Strong induction of IFN-lambda s by LIC-pIC occurred only in human hepatocytes, and not in mouse hepatocytes nor in human cell lines derived from other (non-hepatic) tissues. LIC-pIC-induced IFN-lambda production was mediated by the immune sensor adaptor molecules mitochondrial antiviral signaling protein (MAVS) and Toll/IL-1R domain-containing adaptor molecule-1 (TICAM-1), suggesting dual recognition of LIC-pIC by both sensor adaptor pathways. Conclusions: These findings demonstrate that the expression and function of various IFNs differ depending on the animal species and tissues under investigation. Chimeric mice harboring humanized livers demonstrate that IFN-lambda s play an important role in the defense against human hepatic virus infection.
  • Shigeki Chiba, Muhammad Baghdadi, Hisaya Akiba, Hironori Yoshiyama, Ichiro Kinoshita, Hirotoshi Dosaka-Akita, Yoichiro Fujioka, Yusuke Ohba, Jacob V. Gorman, John D. Colgan, Mitsuomi Hirashima, Toshimitsu Uede, Akinori Takaoka, Hideo Yagita, Masahisa Jinushi
    NATURE IMMUNOLOGY 13 (9) 832 - 842 1529-2908 2012/09 [Not refereed][Not invited]
     
    The mechanisms by which tumor microenvironments modulate nucleic acid mediated innate immunity remain unknown. Here we identify the receptor TIM-3 as key in circumventing the stimulatory effects of nucleic acids in tumor immunity. Tumor-associated dendritic cells (DCs) in mouse tumors and patients with cancer had high expression of TIM-3. DC-derived TIM-3 suppressed innate immune responses through the recognition of nucleic acids by Toll-like receptors and cytosolic sensors via a galectin-9-independent mechanism. In contrast, TIM-3 interacted with the alarmin HMGB1 to interfere with the recruitment of nucleic acids into DC endosomes and attenuated the therapeutic efficacy of DNA vaccination and chemotherapy by diminishing the immunogenicity of nucleic acids released from dying tumor cells. Our findings define a mechanism whereby tumor microenvironments suppress antitumor immunity mediated by nucleic acids.
  • Masahisa Jinushi, Shigeki Chiba, Muhammad Baghdadi, Ichiro Kinoshita, Hirotoshi Dosaka-Akita, Koyu Ito, Hironori Yoshiyama, Hideo Yagita, Toshimitsu Uede, Akinori Takaoka
    Cancer research 72 (1) 56 - 65 0008-5472 2012/01/01 [Not refereed][Not invited]
     
    Although the tumor microenvironment plays a critical role in tumor progression and metastasis, the relationship between chemotherapy resistance and modulation of the tumor microenvironment remains unclear. Here, we report a novel mechanism showing how constitutive DNA damage signals in therapy-resistant tumor cells suppress antitumor immunity in an integrin-αvβ3-dependent manner. Integrin-αvβ3 was upregulated on various therapy-resistant tumor cells through chronic activation of ATM/Chk2-and NFκB-mediated pathways. Inhibiting tumor-specific expression of integrin-αvβ3 improved therapeutic responses to anticancer drugs by stimulating endogenous host immune systems. Mechanistic investigations revealed that tumor-specific integrin-αvβ3 expression targeted dendritic cells, facilitating their ability to phagocytose viable therapy-resistant tumor cells and thereby impaired their ability to cross-prime antigen-specific T lymphocytes. Together, our results clarify the detrimental effects of constitutive DNA damage signals to chemosensitivity and antitumor immunity. Furthermore, these findings suggest that integrin-αvβ3 targeting may benefit patients' refractory to current anticancer regimens by defeating DNA damage signaling-induced immune escape.
  • Chiba S, Baghdadi M, Akiba H, Kinoshita I, Yoshiyama H, Hirashima M, Dosaka-Akita H, Uede T, Takaoka A, Yagita H, Jinushi M
    Nat Immunol 13 (9) 832 - 842 2012 [Not refereed][Not invited]
  • Masahisa Jinushi, Shigeki Chiba, Hironori Yoshiyama, Kenkichi Masutomi, Ichiro Kinoshita, Hirotoshi Dosaka-Akita, Hideo Yagita, Akinori Takaoka, Hideaki Tahara
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 108 (30) 12425 - 12430 0027-8424 2011/07 [Not refereed][Not invited]
     
    Recent evidence has unveiled the critical role of tumor cells with stem cell activities in tumorigenicity and drug resistance, but how tumor microenvironments regulate cancer stem/initiating cells (CSCs) remains unknown. We clarified the role of tumor-associated macrophages (TAMs) and their downstream factor milk-fat globule-epidermal growth factor-VIII (MFG-E8) in the regulation of CSC activities. Bone marrow chimeric systems and adoptive cell transfers elucidated the importance of MFG-E8 from TAMs in conferring to CSCs with the ability to promote tumorigenicity and anticancer drug resistance. MFG-E8 mainly activates signal transducer and activator of transcription-3 (Stat3) and Sonic Hedgehog pathways in CSCs and further amplifies their anticancer drug resistance in cooperation with IL-6. Thus, the pharmacological targeting of key factors derived from tumor-associated inflammation provides a unique strategy to eradicate therapy-resistant tumors by manipulating CSC activities.
  • Shigeru Sasaki, Tadao Ishida, Minoru Toyota, Akinobu Ota, Hiromu Suzuki, Akinori Takaoka, Hiroshi Yasui, Hiroyuki Yamamoto, Hideyasu Takagi, Masahiro Maeda, Tsutomu Seito, Masayuki Tsujisaki, Yasuhisa Shinomura, Kohzoh Imai
    PLOS ONE 6 (5) e19618  1932-6203 2011/05 [Not refereed][Not invited]
     
    Background: Hepatocellular carcinoma (HCC) is the most commonly occurring primary liver cancer and ranks as the fifth most frequently occurring cancer, overall, and the third leading cause of cancer deaths, worldwide. At present, effective therapeutic options available for HCC are limited; consequently, the prognosis for these patients is poor. Our aim in the present study was to identify a novel target for antibody therapy against HCC. Methodology/Principal Findings: We used Western blot and flow cytometric and immunocytochemical analyses to investigate the regulation of FGFR1 expression by interferon-alpha/beta in several human hepatic cancer cell lines. In addition, we tested the efficacy of combined treatment with anti-FGFR1 monoclonal antibody and interferon-alpha/beta in a murine xenograft model of human HCC. We found that interferon-alpha/beta induces expression of FGFR1 in human HCC cell lines, and that an anti-FGFR1 monoclonal antibody (mAb) targeting of the induced FGFR1 can effectively inhibit growth and survival of HCC cells in vitro and in vivo. Moreover, the combination of interferon-alpha, anti-FGFR1 mAb and peripheral blood mononuclear cells (PBMCs) exerted a significant antitumor effect in vitro. Conclusions: Our results suggest that the combined use of an anti-FGFR1 antibody and interferon-alpha/beta is a promising approach to the treatment of HCC.
  • Kensuke Tsushima, Tomoko Osawa, Hideyuki Yanai, Akira Nakajima, Akinori Takaoka, Ichiro Manabe, Yusuke Ohba, Yasushi Imai, Tadatsugu Taniguchi, Ryozo Nagai
    FASEB JOURNAL 25 (5) 1531 - 1543 0892-6638 2011/05 [Not refereed][Not invited]
     
    Hypertension is a typical modern lifestyle-related disease that is closely associated with the development of cardiovascular disorders. Elevation of angiotensin II (ANG II) is one of several critical factors for hypertension and heart failure; however, the mechanisms underlying the ANG II-mediated pathogenesis are still poorly understood. Here, we show that ANG II-mediated cardiac fibrosis, but not hypertrophy, is regulated by interferon regulatory factor 3 (IRF3), which until now has been exclusively studied in the innate immune system. In a ANG II-infusion mouse model (3.0 mg/kg/d), we compared IRF3-deficient mice (Irf3(-/-)/Bcl2l12(-/-)) with matched wild-type (WT) controls. The development of cardiac fibrosis [3.95 +/- 0.62% (WT) vs. 1.41 +/- 0.46% (Irf3(-/-)/Bcl2l12(-/-)); P < 0.01] and accompanied reduction in left ventricle end-diastolic dimension [2.89 +/- 0.10 mm (WT) vs. 3.51 +/- 0.15 mm (Irf3(-/-)/Bcl2l12(-/-)); P=0.012] are strongly suppressed in Irf3(-/-)/Bcl2l12(-/-) mice, whereas hypertrophy still develops. Further, we provide evidence for the activation of IRF3 by ANG II signaling in mouse cardiac fibroblasts. Unlike the activation of IRF3 by innate immune receptors, IRF3 activation by ANG II is unique in that it is activated through the canonical ERK signaling pathway. Thus, our present study reveals a hitherto unrecognized function of IRF3 in cardiac remodeling, providing new insight into the progression of hypertension-induced cardiac pathogenesis.-Tsushima, K., Osawa, T., Yanai, H., Nakajima, A., Takaoka, A., Manabe, I., Ohba, Y., Imai, Y., Taniguchi, T., Nagai, R. IRF3 regulates cardiac fibrosis but not hypertrophy in mice during angiotensin II-induced hypertension. FASEB J. 25, 1531-1543 (2011). www.fasebj.org
  • Sumio Hayakawa, Souichi Shiratori, Hiroaki Yamato, Takeshi Kameyama, Chihiro Kitatsuji, Fumi Kashigi, Showhey Goto, Shoichiro Kameoka, Daisuke Fujikura, Taisho Yamada, Tatsuaki Mizutani, Mika Kazumata, Maiko Sato, Junji Tanaka, Masahiro Asaka, Yusuke Ohba, Tadaaki Miyazaki, Masahiro Imamura, Akinori Takaoka
    NATURE IMMUNOLOGY 12 (1) 37 - U56 1529-2908 2011/01 [Not refereed][Not invited]
     
    The poly(ADP-ribose) polymerases (PARPs) participate in many biological and pathological processes. Here we report that the PARP-13 shorter isoform (ZAPS), rather than the full-length protein (ZAP), was selectively induced by 5'-triphosphate-modified RNA (3pRNA) and functioned as a potent stimulator of interferon responses in human cells mediated by the RNA helicase RIG-I. ZAPS associated with RIG-I to promote the oligomerization and ATPase activity of RIG-I, which led to robust activation of IRF3 and NF-kappa B transcription factors. Disruption of the gene encoding ZAPS resulted in impaired induction of interferon-alpha (IFN-alpha), IFN-beta and other cytokines after viral infection. These results indicate that ZAPS is a key regulator of RIG-I signaling during the innate antiviral immune response, which suggests its possible use as a therapeutic target for viral control.
  • Hui-min Chen, Nobuyuki Tanaka, Yukiko Mitani, Eri Oda, Hiroaki Nozawa, Jian-zhong Chen, Hideyuki Yanai, Hideo Negishi, Myoung Kwon Choi, Toshiroh Iwasaki, Hiroyuki Yamamoto, Tadatsugu Taniguchi, Akinori Takaoka
    CANCER SCIENCE 100 (3) 449 - 456 1347-9032 2009/03 [Not refereed][Not invited]
     
    Interferons-alpha/beta, which are produced upon viral infection, are key soluble factors for the establishment of an antiviral state, but are also produced at low levels in the absence of infection. Herein, we demonstrate that a weak signal by these constitutively produced IFN-alpha/beta show a preventive role in cellular transformation. Ifnar1-deficient (Ifnar1(-/-)) MEF, which are devoid of IFN-alpha/beta signal, undergo a spontaneous transformation during long-term cell culture. Similar to Irf1(-/-) MEF, primary Ifnar1(-/-) MEF become tumorigenic in nude mice by the expression of activated c-Ha-Ras oncoprotein. However, Ifnar1(-/-) MEF do not show any abnormal growth properties. A similar observation is made in Ifnb(-/-) MEF that fail to produce constitutive IFN-alpha/beta, whereas such a transforming property is not found in MEF that lack any of the IFN receptor downstream molecules including Stat1, IRF9 and IRF1. Furthermore, Ifnar1(-/-) mice develop chemically-induced skin papilloma more severely than wild-type mice. In addition, the expression levels of IFNAR1 mRNA are significantly decreased in human gastric cancer tissues. These results suggest a cell-intrinsic role of the weak signal by constitutively produced IFN-alpha/beta to prevent cells from transformation, which may be mediated by a hitherto-unknown pathway(s) downstream of the IFN-alpha/beta receptor. (Cancer Sci 2009; 100: 449-456).
  • TAKAOKA Akinori, SHINOHARA Shigeki
    Uirusu 日本ウイルス学会 58 (1) 37 - 46 0042-6857 2008/06/22 
    Microbial sensing mediated by pattern recognition receptors (PRRs) is the first key step to trigger innate immune responses, represented by the induction of type I interferons (IFNs), proinflammatory cytokines and chemokines. This innate signaling elicits an efficient activation of more specific responses in adaptive immunity. Such coordinated responses in the two systems are essential for the optimal elimination of invading microbes. Despite a major advance in our understanding of RNA sensors, TLR9 remained the only known sensor of DNA. On the other hand, there has been accumulating evidence supporting the existence of TLR9-independent DNA recognition mechanism. In this regard, DAI (also termed as DLM-1/ZBP1), the first sensor of cytosolic DNA, has recently been identified with its activation of IFN-regulatory factors(IRFs) and NF-κB transcriptional factors. Several recent papers suggest the involvement of an additional cytosolic DNA sensor(s). There is also a recent report that cytosolic microbial and host DNA can trigger pro-inflammatory responses via the TLR- and IRF-indepnedent pathway mediated by the inflammasome, which is consisted of NLR family members together with the adaptor protein ASC and caspase-1. In addition, evidence has been provided that host- and virus-derived proteins, which contain DNA-binding motifs (Zα and/or Zβ) similar to those of DAI(DLM-1/ZBP1), negatively regulates the immune response that is activated by cytosolic DNA. Thus, these recent findings reveal the complex DNA-sensing mechanism for triggering the activation of innate immunity, and the breakdown of this sensing mechanism may lead to autoimmune abnormalities.
  • ZhiChao Wang, Myoung Kwon Choi, Tatsuma Ban, Hideyuki Yanai, Hideo Negishi, Yan Lu, Tomohiko Tamura, Akinori Takaoka, Kazuko Nishikura, Tadatsugu Taniguchi
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 105 (14) 5477 - 5482 0027-8424 2008/04 [Not refereed][Not invited]
     
    DNA, whether it is microbe-derived or host-derived, evokes immune responses when exposed to the cytosol of a cell. We previously reported that DNA-dependent activator of IFN regulatory factors (DAI), also referred to as DLM-1/ZBP1, functions as a DNA sensor that activates the innate immune system. In the present study, we examined the regulation of the complex DNA-sensing system by DAI and other molecules. We first show that DAI directly interacts with DNA in vitro and that it requires three DNA-binding domains for full activation in vivo. We also show that the artificially induced dimerization of DAI results in the DNA-independent activation of type I IFN genes, thereby providing a better understanding for the molecular basis of DAI activation. Furthermore, we provide evidence for the presence of additional DNA sensors, either positively or negatively regulating cytosolic DNA-mediated innate immune responses. These results in toto provide insights into the mechanism of DAI activation and reveal the complex regulatory mechanisms underlying DNA-mediated protective and pathologic immune responses.
  • Akinori Takaoka, Tadatsudu Taniguchi
    ADVANCED DRUG DELIVERY REVIEWS 60 (7) 847 - 857 0169-409X 2008/04 [Not refereed][Not invited]
     
    The detection of microbial components by pattern recognition receptors (PRRs) and the subsequent triggering of innate immune responses constitute the first line of defense against infections. Recently, much attention has been focused on cytosolic nucleic acid receptors; the activation of these receptors commonly evokes a robust innate immune response, the hallmark of which is the induction of type I interferon (IFN) genes. In addition to receptors for RNA, receptors that detect DNA exposed in the cytosol and activate innate immune responses have long been thought to exist. Recently, DAI (DLM-1/ZBP1) has been identified as a candidate cytosolic DNA sensor. Cytosolic signaling by DNA-activated DAI (DLM-1/ZBP1) signaling results in activation of the two pathways of gene transcription critical to innate immune responses, the IRF and NF-kappa B pathways. In this review, we summarize our current view of activation mechanism and immunological roles of DAI (DLM-1/ZBP1) and related molecules. In addition, we also discuss the issue of self vs. non-self DNA recognition by DAI (DLM-1/ZBP1) and other DNA sensors in terms of the possible involvement in autoimmune abnormalities. (c) 2007 Elsevier B.V. All rights reserved.
  • Akinori Takaoka, Tomohiko Tamura, Tadatsugu Taniguchi
    CANCER SCIENCE 99 (3) 467 - 478 1347-9032 2008/03 [Not refereed][Not invited]
     
    A family of transcription factors, the interferon regulatory factors (IRF), was identified originally in the context of the regulation of the type I interferon (IFN)-alpha/beta system. The IRF family has now expanded to nine members, and gene-disruption studies have revealed the critical involvement of these members in multiple facets of host defense systems, such as innate and adaptive immune responses and tumor suppression. In the present review article, we aim at summarizing our current knowledge of the roles of IRF in host defense, with special emphasis on their involvement in the regulation of oncogenesis.
  • Akinori Takaoka, ZhiChao Wang, Myoung Kwon Choi, Hideyuki Yanai, Hideo Negishi, Tatsuma Ban, Yan Lu, Makoto Miyagishi, Tatsuhiko Kodama, Kenya Honda, Yusuke Ohba, Tadatsugu Taniguchi
    NATURE 448 (7152) 501 - U14 0028-0836 2007/07 [Not refereed][Not invited]
     
    Central to innate immunity is the sensing of pathogen-associated molecular patterns by cytosolic and membrane-associated receptors(1-4). In particular, DNA is a potent activator of immune responses during infection or tissue damage(5-7), and evidence indicates that, in addition to the membrane-associated Toll-like receptor 9, an unidentified cytosolic DNA sensor(s) can activate type I interferon (IFN) and other immune responses(8-10). Here we report on a candidate DNA sensor, previously named DLM-1 ( also called Z-DNA binding protein 1 (ZBP1))(11), for which biological function had remained unknown; we now propose the alternative name DAI (DNA-dependent activator of IFN-regulatory factors(12)). The artificial expression of otherwise IFN-inducible DAI (DLM-1/ ZBP1) in mouse fibroblasts selectively enhances the DNA-mediated induction of type I IFN and other genes involved in innate immunity. On the other hand, RNA interference of messenger RNA for DAI (DLM-1/ ZBP1) in cells inhibits this gene induction programme upon stimulation by DNA from various sources. Moreover, DAI (DLM-1/ZBP1) binds to double-stranded DNA and, by doing so, enhances its association with the IRF3 transcription factor and the TBK1 serine/threonine kinase. These observations underscore an integral role of DAI (DLM-1/ZBP1) in the DNA-mediated activation of innate immune responses, and may offer new insight into the signalling mechanisms underlying DNA- associated antimicrobial immunity and autoimmune disorders.
  • Hideyuki Yanai, Hui-min Chen, Takayuki Inuzuka, Seiji Kondo, Tak W. Mak, Akinori Takaoka, Kenya Honda, Tadatsugu Taniguchi
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 104 (9) 3402 - 3407 0027-8424 2007/02 [Not refereed][Not invited]
     
    Host defense consists of two main aspects, namely, immune response to invading pathogens and suppression of tumor development. A family of transcription factors, IFN regulatory factors ORB), has recently gained much attention in terms of its critical role in linking these two aspects of host defense, wherein IRF5 was previously shown to play a critical role in the induction of proinflammatory cytokines by activation of Toll-like receptors. In the present study, using IRF5 gene-targeted mice (Irf5(-/-) mice), we demonstrate another facet of theIRIF5function inthe regulationof immune response and tumor suppression. We show that IRF5 is critical for antiviral immunity by showing that Irf5(-/-) mice are highly vulnerable to viral infections, accompanied by a decrease in type I IFN induction in the sera. Furthermore, we show that W5-1fibroblasts are resistant to apoptosis upon viral infection, resulting in an enhanced viral propagation. Finally, we provide evidence that IRF5 is critical for the induction of apoptosis, but not in cell cycle arrest, in response to DNA damage and that IRF5 functions as a tumor suppressor by acting on a pathway that may be distinct from that for p53. These results, together with the dual regulation of IRF5 gene expression by IFN signaling and p53, may provide a new link in the transcriptional network underlying antiviral immunity and tumor suppression.
  • Tsukasa Shibue, Saori Suzuki, Hideaki Okamoto, Hiroki Yoshida, Yusuke Ohba, Akinori Takaoka, Tadatsugu Taniguchi
    EMBO Journal 25 (20) 4952 - 4962 0261-4189 2006/10/18 [Refereed][Not invited]
     
    The activation of tumor suppressor p53 induces apoptosis or cell cycle arrest depending on the state and type of cell, but it is not fully understood how these different responses are regulated. Here, we show that Puma and Noxa, the well-known p53-inducible proapoptotic members of the Bcl-2 family, differentially participate in dual pathways of the induction of apoptosis. In normal cells, Puma but not Noxa induces mitochondrial outer membrane permeabilization (MOMP), and this function is mediated in part by a pathway that involves calcium release from the endoplasmic reticulum (ER) and the subsequent caspase activation. However, upon E1A oncoprotein expression, cells also become susceptible to MOMP induction by Noxa, owing to their sensitization to the ER-independent pathway. These findings offer a new insight into differential cellular responses induced by p53, and may have therapeutic implications in cancer. © 2006 European Molecular Biology Organization | All Rights Reserved.
  • Kohzoh Imai, Akinori Takaoka
    NATURE REVIEWS CANCER 6 (9) 714 - 727 1474-175X 2006/09 [Not refereed][Not invited]
     
    The 'magic bullet' concept of specifically targeting cancer cells at the same time as sparing normal tissues is now proven, as several monoclonal antibodies and targeted small-molecule compounds have been approved for cancer treatment. Both antibodies and small-molecule compounds are therefore promising tools for target-protein-based cancer therapy. We discuss and compare the distinctive properties of these two therapeutic strategies so as to provide a better view for the development of new drugs and the future direction of cancer therapy.
  • Kenya Honda, Akinori Takaoka, Tadatsugu Taniguchi
    Immunity 25 (3) 349 - 360 1074-7613 2006/09 [Refereed][Not invited]
     
    Induction of type I interferons (IFNs) by viruses and other pathogens is crucial for innate immunity, and it is mediated by the activation of pattern-recognition receptors, such as Toll-like receptors and cytosolic receptors such as RIG-I and MDA5. The type I IFN induction is primarily controlled at the gene transcriptional level, wherein a family of transcription factors, interferon regulatory factors (IRFs), plays central roles. Here, we summarize the recent studies on IRFs, providing a paradigm of how genes are ingeniously regulated during immune responses. We also consider some evolutional aspects on the IFN-IRF system. © 2006 Elsevier Inc. All rights reserved.
  • H Takayanagi, K Sato, A Takaoka, T Taniguchi
    IMMUNOLOGICAL REVIEWS 208 181 - 193 0105-2896 2005/12 [Refereed][Not invited]
     
    Interferons (IFNs) play crucial roles in the regulation of a wide variety of innate and adaptive immune responses. Type I interferons (IFN-alpha/beta) are central to the host defense against pathogens such as viruses, whereas type II interferon (IFN-gamma) mainly contributes to the T-cell-mediated regulation of the immune responses. Studies of bone destruction associated with rheumatoid arthritis have highlighted the importance of the interaction between the immune and skeletal systems. Recently, a new research area, termed osteoimmunology, has been spawned by a series of studies focusing on the signaling networks between IFN and other cytokines in bone metabolisms. It has been revealed that IFN-gamma interferes with the osteoclast differentiation induced by receptor activator of nuclear factor-kappa B ligand (RANKL), and this mechanism is critical for the suppression of pathological bone resorption associated with inflammation. In addition, RANKL induces the IFN-beta gene in osteoclast precursor cells, and this induction constitutes a critical aspect of the negative feedback regulation mechanisms of RANKL signaling to suppress excessive osteoclastogenesis. Furthermore, a novel function of signal transducer and activator of transcription 1 (Stat1), the essential transcription factor for both type I and type II IFN responses, was revealed in the regulation of osteoblast differentiation. Collectively, these studies unveil novel aspects of the IFN system and indicate the operation of the intricate signaling network among IFN and other cytokine systems in bone remodeling, which might offer a molecular basis for the treatment of bone diseases.
  • Hideyuki Yanai, Tatsuaki Mizutani, Takayuki Inuzuka, Kenya Honda, Akinori Takaoka, Tadatsugu Taniguchi
    International Congress Series 1285 104 - 113 0531-5131 2005/11 [Refereed][Invited]
     
    The type I interferon (IFN-α/β) gene family was identified about a quarter of century ago as the prototype of many cytokine gene families, and the gene induction mechanism for IFN-α/β was extensively studied in the context of host defense against viral infections. More recently, much attention has been focused on the induction and function of the IFN-α/β system regulated by Toll-like receptors (TLRs), which are critical for linking the innate and adaptive immunities. The understanding of mechanisms underlying IFN-α/β gene induction by TLRs is therefore an emerging theme, for which new insights have been gained over the past few years. We summarise recent progress on the role of interferon regulatory factors (IRFs) in the induction of IFN-α/β genes in normal cells and plasmacytoid dendritic cells (pDCs) that are specialized to produce IFN-α/β at very high levels upon stimulation by TLR9 and its subfamily members. © 2005 Elsevier B.V. All rights reserved.
  • Kenya Honda, Hideyuki Yanai, Akinori Takaoka, Tadatsugu Taniguchi
    International Immunology 17 (11) 1367 - 1378 0953-8178 2005/11 [Refereed][Not invited]
     
    The type I IFN-α/β gene family was identified about a quarter of a century ago as a prototype of many cytokine gene families, which led to the subsequent burst of studies on molecular mechanisms underlying cytokine gene expression and signaling. Although originally discovered for their activity to confer an antiviral state on cells, more evidence has recently been emerging regarding IFN-α/β actions on cell growth, differentiation and many immunoregulatory activities, which are of even greater fundamental biological significance. Indeed, much attention has recently been focused on the induction and function of the IFN-α/β system regulated by Toll-like receptors (TLRs), which are critical for linking the innate and adaptive immunities. The understanding of the regulatory mechanisms of IFN-α/β gene induction by TLRs and viruses is an emerging theme, for which much new insight has been gained over the past few years. © The Japanese Society for Immunology 2005. All rights reserved.
  • Hideo Negishi, Yusuke Ohba, Hideyuki Yanai, Akinori Takaoka, Kiri Honma, Katsuyuki Yui, Toshifumi Matsuyama, Tadatsugu Taniguchi, Kenya Honda
    Proceedings of the National Academy of Sciences of the United States of America 102 (44) 15989 - 15994 0027-8424 2005/11/01 [Refereed][Not invited]
     
    The recognition of microbial components by Toll-like receptors (TLRs) is an event central to the activation of innate and adaptive immune systems. TLR activation triggers the induction of downstream target genes, wherein the TLR-interacting adaptor molecule MyD88 recruits various signaling molecules and transcription factors. Two members of the IFN regulatory factor (IRF) family of transcription factors, IRF-5 and IRF-7, interact with MyD88 and induce proinflammatory cytokines and type I IFNs, respectively. Here, we show that IRF-4 also interacts with MyD88 and acts as a negative regulator of TLR signaling. IRF-4 mRNA is induced by TLR activation, and IRF-4 competes with IRF-5, but not with IRF-7, for MyD88 interaction. The TLR-dependent induction of proinflammatory cytokines is markedly enhanced in peritoneal macrophages from mice deficient in the Irf4 gene, whereas the induction is inhibited by the ectopic expression of IRF-4 in a macrophage cell line. The critical function of IRF-4 in TLR signaling in vivo is underscored by the observation that Irf4-deficient mice show hypersensitivity to DNA-induced shock, with elevated serum proinflammatory cytokine levels. This study may provide an insight into the complex regulatory mechanisms of MyD88 signaling by IRFs. © 2005 by The National Academy of Sciences of the USA.
  • K Honda, Y Ohba, H Yanai, H Negishi, T Mizutani, A Takaoka, C Taya, T Taniguchi
    NATURE 434 (7036) 1035 - 1040 0028-0836 2005/04 [Not refereed][Not invited]
     
    Robust type-I interferon (IFN-alpha/beta) induction in plasmacytoid dendritic cells, through the activation of Toll-like receptor 9 (TLR9), constitutes a critical aspect of immunity(1-6). It is absolutely dependent on the transcription factor IRF-7, which interacts with and is activated by the adaptor MyD88 (ref. 7). How plasmacytoid dendritic cells, but not other cell types (such as conventional dendritic cells), are able to activate the MyD88 IRF-7-dependent IFN induction pathway remains unknown. Here we show that the spatiotemporal regulation of MyD88 IRF-7 signalling is critical for a high-level IFN induction in response to TLR9 activation. The IFN-inducing TLR9 ligand, A/D-type CpG oligodeoxynucleotide (CpG-A)(3,4,8-11), is retained for long periods in the endosomal vesicles of plasmacytoid dendritic cells, together with the MyD88-IRF-7 complex. However, in conventional dendritic cells, CpG-A is rapidly transferred to lysosomal vesicles. We further show that conventional dendritic cells can also mount a robust IFN induction if CpG-A is manipulated for endosomal retention using a cationic lipid. This strategy also allows us to demonstrate endosomal activation of the IFN pathway by the otherwise inactive TLR9 ligand B/K-type oligodeoxynucleotide (CpG-B)(3,4,8-12). Thus, our study offers insights into the regulation of TLR9 signalling in space, potentially suggesting a new avenue for therapeutic intervention.
  • K Honda, H Yanai, H Negishi, M Asagiri, M Sato, T Mizutani, N Shimada, Y Ohba, A Takaoka, N Yoshida, T Taniguchi
    NATURE 434 (7034) 772 - 777 0028-0836 2005/04 [Not refereed][Not invited]
     
    The type-I interferon (IFN-alpha/beta) response is critical to immunity against viruses and can be triggered in many cell types by cytosolic detection of viral infection, or in differentiated plasmacytoid dendritic cells by the Toll-like receptor 9 (TLR9) subfamily, which generates signals via the adaptor MyD88 to elicit robust IFN induction(1-4). Using mice deficient in the Irf7 gene (Irf7(-/-) mice), we show that the transcription factor IRF-7 is essential for the induction of IFN-alpha/beta genes via the virus-activated, MyD88-independent pathway and the TLR-activated, MyD88-dependent pathway. Viral induction of MyD88-independent IFN-alpha/beta genes is severely impaired in Irf7(-/-) fibroblasts. Consistently, Irf7(-/-) mice are more vulnerable than Myd88(-/-) mice to viral infection, and this correlates with a marked decrease in serum IFN levels, indicating the importance of the IRF-7-dependent induction of systemic IFN responses for innate antiviral immunity. Furthermore, robust induction of IFN production by activation of the TLR9 subfamily in plasmacytoid dendritic cells is entirely dependent on IRF-7, and this MyD88-IRF-7 pathway governs the induction of CD8(+) T-cell responses. Thus, all elements of IFN responses, whether the systemic production of IFN in innate immunity or the local action of IFN from plasmacytoid dendritic cells in adaptive immunity, are under the control of IRF-7.
  • A Takaoka, H Yanai, S Kondo, G Duncan, H Negishi, T Mizutani, S Kano, K Honda, Y Ohba, TW Mak, T Taniguchi
    NATURE 434 (7030) 243 - 249 0028-0836 2005/03 [Not refereed][Not invited]
     
    The activation of Toll-like receptors (TLRs) is central to innate and adaptive immunity(1-3). All TLRs use the adaptor MyD88 for signalling(4), but the mechanisms underlying the MyD88-mediated gene induction programme are as yet not fully understood. Here, we demonstrate that the transcription factor IRF-5 is generally involved downstream of the TLR-MyD88 signalling pathway for gene induction of proinflammatory cytokines, such as interleukin-6 (IL-6), IL-12 and tumour-necrosis factor-alpha. In haematopoietic cells from mice deficient in the Irf5 gene (Irf5(-/-) mice), the induction of these cytokines by various TLR ligands is severely impaired, whereas interferon-alpha induction is normal. We also provide evidence that IRF-5 interacts with and is activated by MyD88 and TRAF6, and that TLR activation results in the nuclear translocation of IRF-5 to activate cytokine gene transcription. Consistently, Irf5(-/-) mice show resistance to lethal shock induced by either unmethylated DNA or lipopolysaccharide, which correlates with a marked decrease in the serum levels of proinflammatory cytokines. Thus, our study identifies IRF-5 as a new, principal downstream regulator of the TLR-MyD88 signalling pathway and a potential target of therapeutic intervention to control harmful immune responses.
  • Kenya Honda, Hideyuki Yanai, Tatsuaki Mizutani, Hideo Negishi, Naoya Shimada, Nobutaka Suzuki, Yusuke Ohba, Akinori Takaoka, Wen-Chen Yeh, Tadatsugu Taniguchi
    Proceedings of the National Academy of Sciences of the United States of America 101 (43) 15416 - 15421 0027-8424 2004/10/26 [Refereed][Not invited]
     
    Toll-like receptor (TLR) activation is central to immunity, wherein the activation of the TLR9 subfamily members TLR9 and TLR7 results in the robust induction of type I IFNs (IFN-α/β) by means of the MyD88 adaptor protein. However, it remains unknown how the TLR signal "input" can be processed through MyD88 to "output" the induction of the IFN genes. Here, we demonstrate that the transcription factor IRF-7 interacts with MyD88 to form a complex in the cytoplasm. We provide evidence that this complex also involves IRAK4 and TRAF6 and provides the foundation for the TLR9-dependent activation of the IFN genes. The complex defined in this study represents an example of how the coupling of the signaling adaptor and effector kinase molecules together with the transcription factor regulate the processing of an extracellular signal to evoke its versatile downstream transcriptional events in a cell. Thus, we propose that this molecular complex may function as a cytoplasmic transductional-transcriptional processor.
  • Kenya Honda, Shinya Sakaguchi, Chigusa Nakajima, Ai Watanabe, Hideyuki Yanai, Misako Matsumoto, Toshiaki Ohteki, Tsuneyasu Kaisho, Akinori Takaoka, Shizuo Akira, Tsukasa Seya, Tadatsugu Taniguchi
    Proceedings of the National Academy of Sciences of the United States of America 100 (19) 10872 - 10877 0027-8424 2003/09/16 [Refereed][Not invited]
     
    A complex mechanism may be operational for dendritic cell (DC) maturation, wherein Toll-like receptor and other signaling pathways may be coordinated differently depending on the nature of the pathogens, in order for DC maturation to be most effective to a given threat. Here, we show that IFN-α/β signaling is selectively required for the maturation of DCs induced by double-stranded RNA or viral infection in vitro. Interestingly, the maturation is still observed in the absence of either of the two target genes of IFN-α/β, TLR3 and PKR (double-stranded-RNA-dependent protein kinase R), indicating the complexity of the IFN-α/β-induced transcriptional program in DCs. We also show that the DCs stimulated in vivo by these agents can migrate into the T cell zone of the spleen but fail to mature without the IFN signal. The immune system may have acquired the selective utilization of this cytokine system, which is essential for innate antiviral immunity, to effectively couple with the induction of adaptive immunity.
  • T Shibue, K Takeda, E Oda, H Tanaka, H Murasawa, A Takaoka, Y Morishita, S Akira, T Taniguchi, N Tanaka
    GENES & DEVELOPMENT 17 (18) 2233 - 2238 0890-9369 2003/09 [Refereed][Not invited]
     
    The tumor suppressor p53 exerts its versatile function to maintain the genomic integrity of a cell, and the life of cancerous cells with DNA damage is often terminated by induction of apoptosis. We studied the role of Noxa, one of the transcriptional targets of p53 that encodes a proapoptotic protein of the Bcl-2 family, by the gene-targeting approach. Mouse embryonic fibroblasts deficient in Noxa [Noxa(-/-) mouse embryonic fibroblasts (MEFs)] showed notable resistance to oncogene-dependent apoptosis in response to DNA damage, which was further increased by introducing an additional null zygosity for Bax. These MEFs also showed increased sensitivity to oncogene-induced cell transformation in vitro. Furthermore, Noxa is also involved in the oncogene-independent gradual apoptosis induced by severe genotoxic stresses, under which p53 activates both survival and apoptotic pathways through induction of p21(WAF1/Cip) and Noxa, respectively. Noxa(-/-) mice showed resistance to X-ray irradiation-induced gastrointestinal death, accompanied with impaired apoptosis of the epithelial cells of small intestinal crypts, indicating the contribution of Noxa to the p53 response in vivo.
  • Shinya Sakaguchi, Hideo Negishi, Masataka Asagiri, Chigusa Nakajima, Tatsuaki Mizutani, Akinori Takaoka, Kenya Honda, Tadatsugu Taniguchi
    Biochemical and Biophysical Research Communications 306 (4) 860 - 866 0006-291X 2003/07/11 [Refereed][Not invited]
     
    Type I interferons (IFN-α/β) affect many aspects of immune responses. Many pathogen-associated molecules, including bacterial lipopolysaccharide (LPS) and virus-associated double-stranded RNA, induce IFN gene expression through activation of distinct Toll-like receptors (TLRs). Although much has been studied about the activation of the transcription factor IRF-3 and induction of IFN-β gene by the LPS-mediated TLR4 signaling, definitive evidence is missing about the actual role of IRF-3 in LPS responses in vitro and in vivo. Using IRF-3 deficient mice, we show here that IRF-3 is indeed essential for the LPS-mediated IFN-β gene induction. Loss of IRF-3 also affects the expression of profile of other cytokine/chemokine genes. We also provide evidence that the LPS/TLR4 signaling activates IRF-7 to induce IFN-β, if IRF-7 is induced by IFNs prior to LPS simulation. Finally, the IRF-3-deficient mice show resistance to LPS-induced endotoxin shock. These results place IRF-3 as a molecule central to LPS/TLR4 signaling. © 2003 Elsevier Science (USA). All rights reserved.
  • A Takaoka, S Hayakawa, H Yanai, D Stoiber, H Negishi, H Kikuchi, S Sasaki, K Imai, T Shibue, K Honda, T Taniguchi
    NATURE 424 (6948) 516 - 523 0028-0836 2003/07 [Not refereed][Not invited]
     
    Swift elimination of undesirable cells is an important feature in tumour suppression and immunity. The tumour suppressor p53 and interferon-alpha and -beta (IFN-alpha/beta) are essential for the induction of apoptosis in cancerous cells and in antiviral immune responses, respectively, but little is known about their interrelationship. Here we show that transcription of the p53 gene is induced by IFN-alpha/beta, accompanied by an increase in p53 protein level. IFN-alpha/beta signalling itself does not activate p53; rather, it contributes to boosting p53 responses to stress signals. We show examples in which p53 gene induction by IFN-alpha/beta contributes to tumour suppression. Furthermore, we show that p53 is activated in virally infected cells to evoke an apoptotic response and that p53 is critical for antiviral defence of the host. Our study reveals a hitherto unrecognized link between p53 and IFN-alpha/beta in tumour suppression and antiviral immunity, which may have therapeutic implications.
  • Akinori Takaoka, Tadatsugu Taniguchi
    Cancer Science 94 (5) 405 - 411 1347-9032 2003/05/01 [Refereed][Not invited]
     
    Although interferons (IFNs) were originally identified as humoral factors that confer an antiviral state upon cells, they have been demonstrated to be multifunctional in a variety of biological systems. The IFN-α/β system modulates not only the cellular immune response to viral and bacterial infections, but also the oncogenic process and bone metabolism. Further studies have revealed additional unique facets of the IFN-α/β system. A weak signal by constitutively produced IFN-α/β is critical not only for the regulation of cellular amplification of IFN-α/β production upon viral infection or the enhancement of signalling by other cytokines, but also for the regulation of adaptive immune responses, such as the enhancement of CD8+ T cell activation. Furthermore, IFN-β signalling is critical for the regulation of the bone-resorbing osteoclasts. In this review, we focus on the newly discovered roles of the IFN-α/β system in host defense and bone remodeling, particularly on the functions of the weak IFN-α /β signalling in the context of what we refer to as the "revving-up" model.
  • 谷口 維紹, 高岡 晃教, 本田 賢也, 高柳 広
    日本臨床免疫学会会誌 = Japanese journal of clinical immunology 日本臨床免疫学会 25 (5) 375 - 375 0911-4300 2002/10/31
  • Tadatsugu Taniguchi, Akinori Takaoka
    Current Opinion in Immunology 14 (1) 111 - 116 0952-7915 2002/02/01 [Refereed][Not invited]
     
    The efficient induction of interferons α and β (IFN-α/β) in virus-infected cells is central to the antiviral response of a host and is regulated mainly at the level of gene transcription. Once produced, IFN-α/β transmit signals to the cell interior via a specific receptor complex to induce an antiviral response. Recently, the auto-amplification mechanism of the IFN-α/β system that follows viral infection has been identified. This mechanism is mediated by transcription factors of the IFN regulatory factor family and, in fact, may have evolved to render the system more robust in antiviral responses.
  • A. Takaoka, Y. Tanaka, T. Tsuji, T. Jinushi, A. Hoshino, Y. Asakura, Y. Mita, K. Watanabe, S. Nakaike, Y. Togashi, T. Koda, K. Matsushima, T. Nishimura
    Journal of Immunology 167 (4) 2349 - 2353 0022-1767 2001/08/15 [Refereed][Not invited]
     
    Ag-specific Th1 and Th2 cells have been demonstrated to play a critical role in the induction of allergic diseases. Here we have investigated the precise mechanisms of Th1-induced airway inflammation. Airway inflammation was induced in BALB/c mice by transfer of freshly induced OVA-specific Th1 or Th2 cells followed by OVA inhalation. In this model, both Th1 and Th2 cells induced airway inflammation. The former induced neutrophilia in airways, whereas the latter induced eosinophilia. Moreover, we found that Th1 cells induced more severe airway hyperresponsiveness (AHR) than Th2 cells. The eosinophilia induced by Th2 cell infusion was almost completely blocked by administration of anti-IL-5 mAb, but not anti-IL-4 mAb. In contrast, Th1-induced AHR and pulmonary neutrophilia were inhibited by the administration of anti-human IL-8R Ab, which blocks the function of mouse CXC chemokine(s). These findings reveal a critical role of mouse CXC chemokine(s) in Th1-dependent pulmonary neutrophilia and AHR.
  • Y Mitani, A Takaoka, SH Kim, Y Kato, T Yokochi, N Tanaka, T Taniguchi
    GENES TO CELLS 6 (7) 631 - 640 1356-9597 2001/07 [Refereed][Not invited]
     
    Background: Signalling cross talk provides a molecular basis for modulating a given signalling pathway by another, and it is often critical for regulating cellular responses elicited by cytokines. Previously, we reported on the critical role of the IFN-alpha/beta signalling complex, generated by spontaneously produced IFN-alpha/beta, in efficient IFN-gamma signalling. Results: In the present study, we have demonstrated that the IFN-alpha/beta signalling complex also contributes to efficient IL-6 signalling. In fact, IL-6-induced activation of the Stat1 and Stat3 transcription factors is markedly diminished in the absence of the IFN-alpha/beta signalling complex. The induction of several target genes for these factors is also diminished, both in vitro and in vivo. We provide evidence that the cytoplasmic tyrosine residues of IFNAR-1, which remains phosphorylated by a weak IFN-alpha/beta stimulation, provide docking sites for Stat1 and Stat3 to form homo- or heterodimers following IL-6 stimulation. Furthermore, a chemical cross-linking experiment revealed that IFNAR-1 and gp130, a common signal transducer for the IL-6 family of cytokines, exist in close proximity. Conclusions: The constitutive weak IFN-alpha/beta signal provides a foundation for strong cellular responses to IL-6, IFN-gamma, and possibly other cytokines. Our results also suggest the assembly of cytokine receptor subunits, which may represent a 'receptosome'-Iike structure, allowing the unique signalling cross talks to occur.
  • T Taniguchi, A Takaoka
    NATURE REVIEWS MOLECULAR CELL BIOLOGY 2 (5) 378 - 386 1471-0072 2001/05 [Not refereed][Not invited]
     
    Biological systems have acquired adaptability and robustness against rapid environmental changes. A typical example is the immune system, which eradicates invading pathogens such as viruses, interferons alpha and beta, which are produced in response to viral infection, are essential components of this system but are also produced at low levels in the absence of infection. What is the purpose of the constitutive weak interferon-alpha/beta signal?
  • T Taniguchi, K Ogasawara, A Takaoka, N Tanaka
    ANNUAL REVIEW OF IMMUNOLOGY 19 623 - 655 0732-0582 2001 [Not refereed][Not invited]
     
    Interferon regulatory factors (IRFs) constitute a family of transcription factors that commonly possess a novel helix-turn-helix DNA-binding motif. Following the initial identification of two structurally related members, IRF-1 and IRF-2, seven additional members have now been reported. In addition, virally encoded IRFs, which may interfere with cellular IRFs, have also been identified. Thus far, intensive functional analyses have been done on IRF-1, revealing a remarkable functional diversity of this transcription factor in the regulation of cellular response in host defense. Indeed, IRF-1 selectively modulates different sets of genes, depending on the cell type and/or the nature of cellular stimuli, in order to evoke appropriate responses in each. More recently, much attention has also been focused on other IRF family members. Their functional roles, through interactions with their own or other members of the family of transcription factors, are becoming clearer in the regulation of host defense, such as innate and adaptive immune responses and oncogenesis.
  • Naoki Hata, Mitsuharu Sato, Akinori Takaoka, Masataka Asagiri, Nobuyuki Tanaka, Tadatsugu Taniguchi
    Biochemical and Biophysical Research Communications 285 (2) 518 - 525 0006-291X 2001 [Refereed][Not invited]
     
    Efficient IFN-α/β gene induction in virus-infected cells is an event central to innate immunity, in which the transcription factor IRF-7 plays a critical role together with IRF-3. Unlike IRF-3, IRF-7 is short-lived and its gene expression is dependent on IFN-α/β signalling hence, the signal-dependent enhancement of IRF-7 gene induction during viral infection is essential for positive-feedback regulation of IFN-α/β gene induction. Here, we provide evidence that constitutive, IRF-3/IRF-7-independent production of IFN-α/β in uninfected cells is critical for setting the IRF-7 expression levels, determining whether or not the positive-feedback mechanism will operate effectively upon viral infection. In fact, spleen cells are more dependent than fibroblasts on this mechanism the IFN-α/β gene induction is impaired more severely by blocking the IRF-7 induction pathway than by introducing an IRF-3 null mutation. Thus, the constitutive IFN-α/β signal provides a foundation for the IRF-7-mediated enhancement of its own production in response to virus infection. © 2001 Academic Press.
  • H Takayanagi, K Ogasawara, S Hida, T Chiba, S Murata, K Sato, A Takaoka, T Yokochi, H Oda, K Tanaka, K Nakamura, T Taniguchi
    NATURE 408 (6812) 600 - 605 0028-0836 2000/11 [Refereed][Not invited]
     
    Bone resorption is regulated by the immune system(1,2), where T-cell expression of RANKL (receptor activator of nuclear factor (NF)-kappaB ligand), a member of the tumour-necrosis factor family that is essential for osteoclastogenesis, may contribute to pathological conditions, such as autoimmune arthritis(3,4). However, whether activated T cells maintain bone homeostasis by counterbalancing the action of RANKL remains unknown. Here we show that T-cell production of interferon (IFN)-gamma strongly suppresses osteoclastogenesis by interfering with the RANKL-RANK signalling pathway. IFN-gamma induces rapid degradation of the RANK adapter protein, TRAF6 (tumour necrosis factor receptor-associated factor 6), which results in strong inhibition of the RANKL-induced activation of the transcription factor NF-kappaB and JNK. This inhibition of osteoclastogenesis is rescued by overexpressing TRAF6 in precursor cells, which indicates that TRAF6 is the target critical for the IFN-gamma action. Furthermore, we provide evidence that the accelerated degradation of TRAF6 requires both its ubiquitination, which is initiated by RANKL, and IFN-gamma -induced activation of the ubiquitin-proteasome system. Our study shows that there is cross-talk between the tumour necrosis factor and IFN families of cytokines, through which IFN-gamma provides a negative link between T-cell activation and bone resorption. Our results may offer a therapeutic approach to treat the inflammation-induced tissue breakdown.
  • S Tsujino, JP Di Santo, A Takaoka, TL McKernan, S Noguchi, C Taya, H Yonekawa, T Saito, T Taniguchi, H Fujii
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 97 (19) 10514 - 10519 0027-8424 2000/09 [Not refereed][Not invited]
     
    The common cytokine receptor gamma chain (gamma c), a shared component of the receptors for IL-2, IL-4, IL-7, IL-9, and IL-15, is critical for the development and function of lymphocytes. The cytoplasmic domain of gamma c consists of 85 aa, in which the carboxyl-terminal 48 aa are essential for its interaction with and activation of the Janus kinase, Jak3. Evidence has been provided that Jak3-independent signals might be transmitted via the residual membrane-proximal region; however, its role in vivo remains totally unknown. In the present study, we expressed mutant forms of gamma c, which lack either most of the cytoplasmic domain or only the membrane-distal Jak3-binding region, on a gamma c null background. We demonstrate that, unlike gamma c or Jak3 null mice, expression of the latter, but not the former mutant, restores T lymphopoiesis in vivo, accompanied by strong expression of Bcl-2. On the other hand, the in vitro functions of the restored T cells still remained impaired. These results not only reveal the hitherto unknown role of the gamma c membrane-proximal region, but also suggest the differential requirement of the cytoplasmic subregions of gamma c in T cell development and function.
  • A Takaoka, Y Mitani, H Suemori, M Sato, T Yokochi, S Noguchi, N Tanaka, T Taniguchi
    SCIENCE 288 (5475) 2357 - 2360 0036-8075 2000/06 [Not refereed][Not invited]
     
    Definition of cellular responses to cytokines often involves cross-communication through their respective receptors. Here, signaling by interferon-gamma (IFN-gamma) is shown to depend on the IFN-alpha/beta receptor components. Although these IFNs transmit signals through distinct receptor complexes, the IFN-alpha/beta receptor component, IFNAR1, facilitates efficient assembly of IFN-gamma-activated transcription factors. This cross talk is contingent on a constitutive subthreshold IFN-alpha/beta signaling and the association between the two nonligand-binding receptor components, IFNAR1 and IFNGR2, in the caveolar membrane domains. This aspect of signaling cross talk by IFNs may apply to other cytokines.
  • Akinori Takaoka, Nobuyuki Tanaka, Yukiko Mitani, Tadaaki Miyazaki, Hodaka Fujii, Mitsuharu Sato, Pavel Kovarik, Thomas Decker, Joseph Schlessinger, Tadatsugu Taniguchi
    EMBO Journal 18 (9) 2480 - 2488 0261-4189 1999/05/04 [Refereed][Not invited]
     
    Two distinct types of interferon, IFN-α/β and IFN-γ, commonly exhibit antiviral activities by transmitting signals to the interior of the cell via their homologous receptors. Receptor stimulation results in the activation of distinct combinations of Janus family protein tyrosine kinases (Jak PTKs) Jak1/Tyk2 and Jak1/Jak2 for IFN-α/β and IFN-γ, respectively. Jak PTK activation by these IFNs is commonly followed by tyrosine phosphorylation of the transcription factor Stat1 at Y701, which is essential for dimerization, translocation to the nucleus and DNA-binding activity. To gain full transcriptional activity, Stat1 also requires serine phosphorylation at S727. In this paper we demonstrate that Pyk2, which belongs to another PTK family, is critical for the Jak-mediated MAPK and Stat1 activation by IFN-γ, but not IFN-α. Pyk2 is selectively associated with Jak2 and activated by IFN-γ. Overexpression of PKM, a dominant interfering form of Pyk2, in NIH 3T3 cells results in a strong inhibition of the IFN-γ-induced activation of Erk2, serine phosphorylation of Stat1 and Stat1-dependent gene transcription. Finally, the antiviral action of IFN-γ, but not IFN-α, is severely impaired by PKM overexpression. Thus, the two types of IFN may utilize distinct Jak-mediated Erk2, and possibly other MAPK activation pathways for their antiviral action.
  • T. Taniguchi, N. Tanaka, K. Ogasawara, S. Taki, M. Sato, A. Takaoka
    Cold Spring Harbor Symposia on Quantitative Biology 64 465 - 472 0091-7451 1999 [Refereed][Not invited]
  • Tadaaki Miyazaki, Akinori Takaoka, Leonor Nogueira, Ivan Dikic, Hodaka Fujii, Shiho Tsujino, Yukiko Mitani, Michiyuki Maeda, Joseph Schlessinger, Tadatsugu Taniguchi
    Genes and Development 12 (6) 770 - 775 0890-9369 1998/03/15 [Refereed][Not invited]
     
    Many cytokines transmit signals to the cell interior through activation of receptor-associated, Janus family protein tyrosine kinases (Jak PTKs). The interleukin-2 receptor (IL-2R) is associated with the Jak1 and Jak3 PTKs, and ligand-induced activation of these PTKs is essential for lymphocyte proliferation. Here, the nonreceptor PTK, Pyk2, was found to be activated following IL-2 stimulation in a Jak-dependent manner. Furthermore, physical association was detected between endogenous Pyk2 and Jak3, and a dominant interfering mutant of Pyk2 inhibited IL-2-induced cell proliferation without affecting Stats activation. Collectively, these results suggest that Pyk2 is a newly identified component of the Jak-mediated IL-2 signaling pathway.
  • Mlnoru Toyota, Yuji Hlnoda, Naoaki Nakagawa, Yoshiaki Arimura, Shigeru Tokuchi, Akinori Takaoka, Shingo Kitagawa, Toshihiro Usuki, Tsuyoshi Yabana, Akira Yachi, Kohzoh Imai
    Journal of Gastroenterology 31 (5) 710 - 713 0944-1174 1996 [Refereed][Not invited]
     
    Gastric antral vascular ectasia (GAVE) that caused continuous gastrointestinal bleeding is reported in a 76-year-old woman who had been treated with repeated blood transfusions because of severe anemia. Endoscopic examination was performed and diffuse speckled telangiectasia of the entire antrum was observed. Laboratory data showed SGOT > SGPT, decreased chE level and the increased levels of serum gastrin and ICG at 15 min. Anti-HCV antibody was positive. Image examination revealed splenomegaly. There was no family history of telangiectasia, and no telangiectasia was found in other organs. The diagnosis was established as GAVE with liver cirrhosis. Surgical resection of the distal stomach resulted in termination of the bleeding, and the cirrhotic changes of the surface of the liver were revealed at that time providing further evidence of liver cirrhosis. Although the pathogenesis of GAVE is unknown, liver cirrhosis and hypergastrinemia are thought to be associated with the condition. Importantly, this condition is a cause of severe gastrointestinal bleeding in elderly patients.

MISC

Presentations

  • Direct and indirect roles of RIG-I for antiviral defense against hepatitis B virus in human hepatocytes  [Not invited]
    TAKAOKA Akinori
    International Conference on Antimicrobial Research  2014/10
  • Role of the cytoplasmic RNA sensor RIG-I in innate immune defense against hepatitis B virus infection  [Not invited]
    TAKAOKA Akinori
    11th International Conference on Innate Immunity  2014/06
  • ZAPS acts as a key factor of RIG-I-mediated activation of innate immune responses during influenza virus  [Not invited]
    TAKAOKA Akinori
    2nd International Conference on Clinical & Cellular Immunology  2013/10
  • Innate immune signaling networks during host-microbe interaction  [Not invited]
    TAKAOKA Akinori
    CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences  2013/07
  • Nucleic acid sensors for detecting viral infection  [Not invited]
    髙岡 晃教
    IEIIS2012 Homeostatic Inflammation Symposium  2012/10
  • Roles of ZAPS as an antiviral regulator in innate immunity  [Not invited]
    髙岡 晃教
    2nd CSI/JSI/KAI Joint Symposium on Immunology (2011日中韓 合同 免疫シンポジウム)  2011/12
  • Identification of a novel regulator of the innate signaling activated by virus-derived nucleic acids  [Not invited]
    髙岡 晃教
    2010 annual meeting of the french society for immunology  2010/11
  • Activation of Innate Immune Response Mediated by DNA-triggered Danger Signals  [Not invited]
    髙岡 晃教
    The 36th Congress of the International Society of Oncology & BioMarkers  2008/10

Association Memberships

  • 日本ウイルス学会   日本免疫学会   International Society for Interferon and Cytokine Research   International Cytokine Society   日本分子生物学会   日本癌学会   北海道医学会   北海道癌談話会   日本生化学会   がん分子標的治研究会   日本インターフェロン・サイトカイン学会   

Research Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2022/04 -2027/03 
    Author : 高岡 晃教
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : Kameyama Takeshi
     
    Interferons (IFNs) are the main cytokines for the innate immune response against viral infection. It is known that IFNs are constitutively induced at very low levels in the absence of viral infection. These constitutively induced IFNs and their signals are essential for the rapid and robust induction of IFN induction after viral infection and for the suppression of carcinogenesis. However, the mechanism of this constitutive IFN induction and its regulation remains unclear. In this study, we found that the constitutive IFNs are induced through an intracellular RNA sensor-dependent recognition of endogenous RNAs and the downstream signaling pathway. Furthermore, we found several regulatory factors that regulate cytosolic nucleic acid-mediated innate immune responses. These results identified a novel regulatory mechanism that controls constitutively induced IFNs, which may provide a novel prophylactic target for viral control and suppression of carcinogenesis.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/06 -2020/03 
    Author : Takaoka Akinori
     
    We have been working on the study of innate signaling via pattern recognition mediated receptor for antiviral responses. In this study, we identified a novel innate signaling pathway via cytosolic RNA sensor RIG-I that activates cell death in cancer cells but not normal cells. This novel pathway is different from conventional pathway via MAVS/IPS-1 mediated IFN inducing pathway. Importantly, localization of a kinase protein is not only nucleus but also cytosol in cancer cells while the localization of this is only nucleus in normal cells. RIG-I in cancer cells activate this kinase and activates apoptosis in cancer cells. Based on our finding that a kinase is localized in cytosol of cancer cells, we propose a novel strategy to modulate ectopic protein for cancer therapy for cancer cells' death.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013/04 -2018/03 
    Author : Takaoka Akinori
     
    Viral infection is one of the most critical problems for our health. Elucidation of host immune response against invading viruses is crucial for better understanding of the pathological processes and viral elimination to control viral infection. In this study, we reveal that PARP-13 shorter isoform (ZAPS) is involved in the post-transcriptional regulation of RSAD2 mRNA, one of the interferon-stimulated genes, which provide a novel host defense mechanism for elimination of viruses.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : HAYAKAWA Sumio
     
    Food is recognized as one of the important factors which regulate human health such as immune response. It is known that vitamins, minerals and proteins are essential nutrients to build a healthy body. However, the role of food DNA on health is not clearly understood. So, we focused on the effect of food DNA on activation of innate immune signaling pathway mediated by PRRs. Here we show that a complex with the food DNA and short peptide, the only cathelicidin-derived antimicrobial peptide, activated innate immune response and functioned as a ligand of RIG-I in macrophage. We suggest that DNA from food could provide an application in therapy aimed at maintaining good health.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2013/04 -2015/03 
    Author : 高岡 晃教
     
    健常人に広く潜伏感染しながら，特に臓器移植患者などで重篤な感染症を引き起こすDNAウイルスであるヒトサイトメガロウイルス（HCMV）は，日和見病原体として臨床では大きな問題となっているが，その自然免疫認識機構についてはまだ充分に明らかにされていない．そこで，HCMV感染を認識するPRRの同定を試みた結果，既知のDNAセンサー分子の中でIFI16がHCMV感染による自然免疫応答の活性化に関与することを示唆した．一方，IFI16に会合するHCMV由来のタンパク質として，構造タンパク質を見出した．このような結果を基に本研究では，HCMV感染によるIFI16経路の活性化の分子基盤を明らかにすることを目的とした． 我々はHCMV感染時に活性化される自然免疫応答に既知の細胞質DNAセンサー分子IFI16が関与することを見出したが，HCMV由来のDNAはIFI16に認識されない可能性が示唆され，IFI16はHCMV由来の未知なる因子を認識している可能性が考えられた．一方，IFI16に会合することを新たに見出した，HCMV由来の構造タンパク質を細胞に過剰発現しただけでもIFI16依存的な自然免疫応答の活性化が認められた．さらに，この構造タンパク質をエンコードする遺伝子を欠損させたHCMVを用いた実験により，実際のHCMV感染時においてこの構造タンパク質が自然免疫応答を活性化することが確認された．一方，この構造タンパク質は酵素活性を有することが報告されていることから，この酵素活性のIFI16認識経路への影響についての検討を行った．その結果，この酵素活性はIFI16との会合に影響は与えなかったが，この構造タンパク質の酵素活性変異体を細胞に過剰発現させても自然免疫応答は認められなかった．このことは，この構造タンパク質の酵素活性にIFI16経路をONにする役割があることを示唆していると考えている．
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013/04 -2015/03 
    Author : TAKAOKA Akinori, SATO Seiichi, KAMEYAMA Takeshi
     
    Adjuvant is an important component for effective vaccination and antitumor therapy. Establishment of local and switchable adjuvant is considered to be an efficient strategy to reduce side effects and efficiently activate innate immune responses. The purpose of this study is the establishment of a novel nucleic acid adjuvant that can trigger the activation of innate immune system in response to X-ray irradiation. In this study, type-C CpG ligands contained with cystamine-modified cytosine were used and showed its structural change by X-ray irradiation, albeit their low efficiency. These results showed these ligands could be a switchable activator and further investigation will be needed to improve their efficiency.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2011/04 -2013/03 
    Author : 高岡 晃教
     
    申請者がこれまで行ってきた自然免疫活性化機構に関する研究成果に基づき，RNAによって規定される生体防御の分子メカニズムや制御機構について，ウイルスRNAと宿主RNAの両方に視点を当てて解明することを目的とし，①直接作用(RNAの分解)と間接作用(RNA認識による免疫賦活)という2つの局面から追究すること,②宿主RNAを介する生体防御機構の制御について新しい仕組みを見出すことを目指した. ①について，申請者らが独自に同定した自然免疫調節因子ZAPSに着目し，その機能制御がDEAD box RNAヘリカーゼp72によって行われている可能性について調べた．その結果，ZAPSは細胞質においてp72と共局在しタンパク中央部分で会合すること，さらにRIG-IによるIFN誘導をZAPS依存的に正に制御することを見出した．そのメカニズムとしてRIG-I-ZAPS複合体をp72が活性化することが考えられた．②について，通常非感染細胞においてはごくわずかなI型IFNを構成的に発現することが知られているがその詳細については明らかになっていない．そこで本研究では，構成的なIFNの発現制御機構を調べた．その結果，構成的なIFNの発現は，RIG-I-ZAPSの経路に依存していることを見出した．さらにRIG-Iに結合する宿主RNAが存在し，このRNAは自然免疫系を活性化することを見出した．今後非感染時においてRIG-Iに結合するRNAを網羅的に解析し，構成的なIFNの発現制御機構を明らかにする予定である. このような本申請研究によって,ウイルスRNAと宿主RNAの2つの観点から，RNAプログラムによって制御される生体防御機構を明らかにしたことは，感染症においてRNA制御という新しい研究領域の推進や，疾患治療における新たな治療標的を創出することに大いに貢献することが考えられる.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2011 -2013 
    Author : KAMEYAMA Takeshi, HAYAKAWA Sumio, ADACHI Yoshihiro Christopher, TAKAOKA Akinori, OKADA Kanako, TODA Haruka
     
    Diet contains various kinds of nutrient,, which keep us healthy. However the nutritional role of nucleic acids derived from diets is not clearly understood. The innate immunity system is an essential step as the front line of host defense. Although oral mucosa acts as powerful barriers, the importance of oral mucosa in innate immunity remains unclear. In this study, we demonstrate that DNA derived from vegetable activated innate immune response both in vitro and in vivo, which may provide the nutritional immunological role of dietary nucleic acids.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2008 -2012 
    Author : TAKAOKA Akinori
     
    In this project, we tried to elucidate a regulatory mechanism for the activation of PRRs, particularly nucleic acid sensors, and the related signaling pathways, leading to the induction of cytokine/chemokine genes in innate immune responses for host defense against viral infection and cancer. First, we found that the poly(ADP-ribose) polymerase (PARP)-13 shorter isoform (ZAPS) critically functions as a potent stimulator of IFN responses in human cells mediated by RIG-I, through the physical association of ZAPS with RIG-I. Next, we revealed that ZAPS is a factor targeted by Influenza viral NS1 protein for viral innate immune evasion. In addition, we showed a role of PARP-7/TIPARP and PARP-12 as a possible negative regulator of RIG-I-meditated innate immune signalings. Furthermore, we also identified a candidate DNA sensor for human cytomegalovirus (HCMV). On the other hand, this project contributed to the research, wherein it has been shown a novel mechanism for the suppression of innate immune signalings mediated by tumor-derived DNA in tumor-infiltrating dendritic cells. These results may provide a therapeutic and preventive insight for the control of viral infection and cancer.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2009 -2010 
    Author : 高岡 晃教
     
    本研究では、細胞質に存在するウイルス由来DNAを介して誘導される自然免疫応答の基盤となる細胞内認識機構や下流の遺伝子発現プログラムの活性化に至るシグナル伝達経路を明らかにすることを目的に研究を進めた結果、本年度においては、新しいシグナル制御因子ZAPSを同定するに至った。ZAPSは、PARP(poly(ADP-ribose)polymerase)スーパーファミリーに属するPARP-13のアイソフォームの1つであり、I型インターフェロン(IFN)によって誘導する遺伝子である。実際に、ZAPSを過剰発現させたヒトHEK293T細胞においてB型DNA(poly(dA-dT)・poly(dT-dA))をトランスフェクトすることで誘導されるIFN-β、TNF-α、IL-6、CXCL10 mRNAの発現誘導が大きく増強された。一方、HEK293T細胞においてZAPSの発現をsiRNAによって抑制した場合、B型DNAによるIFN-βmRNAの発現誘導が有意に抑制された。この際のIFN発現誘導に必須のIRF-3転写因子の二量体形成が抑制されることも見出している。これらの結果は、HEK293T細胞においてB型DNAによって誘導される自然免疫シグナル経路においておそらく上流でZAPS分子が正に制御していることが示唆された。また、蛍光顕微鏡による解析で、ZAPSは細胞質に存在し、B型DNAによる刺激によって顆粒状に集合体を形成することも見出した。ZAPSはN末端にzincフィンガーモチーフを複数有しているが、この領域を欠損した変異型ZAPSを用いた解析で、この領域がB型DNAによる自然免疫応答に必要であることを示した。以上の結果から、ZAPSはHEK293T細胞においてB型DNAによって誘導されるI型IFN発現をはじめとする自然免疫応答を増強する新しい宿主側の制御因子であることが示された。
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2008 -2009 
    Author : 高岡 晃教
     
    これまでのI型インターフェロン(IFN)シグナルの研究をがん治療の領域において発展させた形で,がんの抗体治療の新しいストラテジーを提案し,臨床応用へ向けた分子基盤を見出すことを目的として研究を推進した.まず細胞表面のタンパク質をビオチン化させる方法を用いて,IFN-βに応答してがん細胞に比較的選択的にその発現レベルが顕著に増強する分子群を同定し,その結果,5つのターゲット分子に着目した.今年度,まず,これら5つの候補分子の細胞外領域に対するモノクローナル抗体の作製を行った.スクリーニングの結果,今年度内に抗体を用いた解析が可能となった2つのターゲットSCI101とSCI102について検討を進めた.皮下に担がんさせたマウスの系において,これらの抗体を用いて,IFN投与後の腫瘍内組織のターゲット分子のタンパク質発現レベルを経時的に検討したところ,昨年度検討した担がんSCIDマウスを用いた系での実験結果とconsistentな結果が得られた. SCI101の方がIFN刺激後16時間目をピークに24時間目にはその二分の一以下にタンパク質の発現レベルが低下するのに対し,SCI102はもう少し早い発現経過を示し,6時間目がピークで,24時間目にはほとんど発現レベルは無刺激のレベルに近くなる結果となった.次に,発現プロファイルを元に,IFN-β投与群と非投与群で治療抗体の抗腫瘍効果を検討した.発現ピークの1時間前に尾静脈より抗体投与を5日間行なった結果,IFN-β投与のみでも非投与群と比べ,腫瘍径の減少がみとめられたが,抗体投与を併用した群の方が,IFN-β投与のみよりもより,腫瘍が縮小する傾向がみとめられた.現在,数を増やして再現性を検討している.また蛍光物質をラベルした治療抗体を用いて,IFN投与による治療抗体の腫瘍局所への集積の検討を行っており,できるだけ早急に論文にまとめることを予定している.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2007 -2009 
    Author : 高岡 晃教
     
    本研究では,現在広く臨床応用されているIFN-α/β製剤に関して問題となっている副作用の軽減を目指し,より効率の良い効果をもたらすIFN分子の改良を試み,とくに脳神経系の腫瘍であるグリオーマに対する検討を行うこと,さらにはこれを発展させて,脳神経系の領域におけるIFN biologyの解明にもせまることを目的として昨年度より実験を進めてきた.本研究においては,ヒトIL-2受容体α鎖の細胞内領域および膜貫通領域をヒトIFN-βに融合させたタンパク質をデザインすることで,IFN-βを細胞膜表面に固定し,周囲への分散を抑制することによってIFNの副作用を抑えることを目指した.しかしながら,この膜結合型IFNは,膜表面に発現されるよりも細胞外に分泌されてしまう割合が9割をしめるという問題が浮上し,本年度は,この問題点を解決すべく,効率よく細胞膜に局在する分子を設計しなおすことを進めていた.まず,ヒトIL-2受容体α鎖とヒトIFN-βとの間に(Gly-Gly-Gly-Gly-Ser)x3という配列のリンカーを挟んで両者を結合させたタンパク質をデザインしていたが,そのリンカー部分の長さを変えることで検討したところ,当初の15個のアミノ酸残基数よりも長い50個のアミノ酸残基数に変えたところ,膜表面に発現される割合は5割までに改善されることを見出した.しかしながらまだ5割は細胞外に分泌されてしまうため,更なる改善が必要と考えられた.本年度,開始から1か月半を経た現時点で,若手(S)の研究費が支給されることに決まった.そのため,本研究費はその重複規定の剃限に従い,この時点をもって本課題に対する研究費の支給が停止されることになる.若手研究費による新たに始まる研究は感染やがんに対する自然免疫応答をとくにIFN応答を誘導するパターン認識受容体を介するシグナル伝達を解明するものであり,これまで行ってきた基盤(B)による研究結果も生かし,さらに発展させた研究を展開させていきたいと考えている.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2005 -2009 
    Author : TANIGUCHI Tadatsugu, TAKAOKA Akinori, TAMURA Tonohiko, HONDA Kenya, OOBA Yuusuke, YANAI Hideyuki
     
    We investigated biological mechanisms and role of effecter molecules, e.g. interferons, IRFs and Noxa. It revealed that these molecules are involved in transformation, apoptosis induction and metastasis signaling pathways. We also found the cross-talk pathway between TLRs signaling. Moreover, we identified DAI and HMGB1, 2, 3 are important for the nucleic-acid mediated innate immune responses. Since these pathways regulate tumorgenesis and exacerbation, our findings will be proved to be useful for the development of novel tumor therapy in near future.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2007 -2008 
    Author : 高岡 晃教
     
    これまで多くのIRFファミリーメンバーが病原体認識受容体下流で活性化を受け, 宿主細胞における自然免疫応答に関与することを示してきた. 昨年度, IRF-3やIRF-7の活性化を誘導する細胞質型DNA認識受容体の候補分子としてDAI(DML-1/ZBP1)を同定するに至ったが, 本年度は, このDAIに関する研究をさらに進め, DAIのリガンド特性や活性化機構の解析を行った. その結果, リコンビナントのDAI (DML-1/ZBP1) タンパク質を作製し, in vitroの系においてB型DNAとの直接的な結合を示すことができ, かつこの結合はB型DNAをはじめ, ISD (IFN-stimulatory DNA) や, Z-DNAをとることが知られているpoly(dG-dC)の過剰投与によって競合されることが示された. またDAI(DML-1/ZBP1)の活性化には, リガンドとして少なくとも100bp以上の長いDNAが必要であることおよび, DAI(DML-1/ZBP1)のN末側の2つのZα, Zβドメインに加え, D3ドメインの3つの領域が必要であることも見出した. さらに人工的にDAI(DML-1/ZBP1)分子の二量体を形成することでI型IFNsの発現の誘導がみとめられた.一方で, このようなDAI(DML-1/ZBP1)の細胞質DNA応答における役割はredundantなものであることを示す結果も得られた. 加えて, DAIと共通の保存された領域をもつ宿主由来のタンパク質ADAR1やウイルス由来のE3Lについて検討した結果, 共に細胞内DNA応答について負に制御していることが明らかとなった.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2004 -2005 
    Author : TAKAOKA Akinori, HONDA Kenya
     
    In this study, we analyzed the molecular mechanism for antiviral defense triggered by interferon-α / (IFN-α/β) and the signalling pathways which lead to type I IFN gene induction by TLR activation. In particular, we focused on IFN-regulatory factors (IRFs), which are known to be essential factors upon viral infection, and have elucidated several novel roles of the IFN-IRF system in activation of innate immune response. First, we found that the level of p53 gene, which is known to encode a tumor suppressor, is upregulated by IFN treatment through activation of ISGF3 transcriptional complex, contributing to enhancement of p53 response to stress signals. We showed that p53 is phosphorylated and activated upon viral infection, and that p53 is essentially involved in the induction of apoptosis in virally infected cells. This result demonstrated an interrelationship between IFN-α/β signaling and p53-mediated response, which provided a novel aspect in terms of a linkage between tumor suppression and immunity. Second, we analyzed various hideficient mice to show that IRF-7 mediates a novel MyD88-dependent pathway for the induction of type I IFN gene expression by TLR9 subfamily members in plasmacytoid dendritic cells (pDCs). In addition, we found a spaciotemporal regulation, by which pDCs are capable to produce high levels of IFN- α/β. On the other hand, IRF-5 is found to be essentially involved in TLR-mediated production of proinflammatory cytokines. Recently, we also found that IRF-5 is activated upon viral infection and plays a role in virus-induced apoptosis in a distinct manner from p53. Another IRF-family member, IRF-4, is shown to be a negative regulator of IRF-5 by competitively inhibiting the interaction of IRF-5 with MyD88. Thus, we demonstrated that IRF-family transcriptional factors are critical downstream mediators of TLRs to regulate the activation of innate immune response.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2000 -2004 
    Author : TANIGUCHI Tadatsugu, TAKAOKA Akinori, HONDA Kenya
     
    In the current study, we have made multifaceted approach to elucidate molecular mechanisms for oncogenesis, by analyzing not only the interrelationships between molecules which are involved in tumor suppression but also the gene expression network from both genetic and epigenetic aspects. Specifically, we found several important roles of "weak signal" by constitutively produced IFN-α/β in IFN-γ or IL-6-mediated cellular response as well as regulatory systems for cancer prevention. We also found a novel cross-talk mechanism between RANKL and IFN-γ, and clarified the regulatory role of the IFN system in osteoclast differentiation, which provided its putative therapeutic application to bone destruction by metastatic tumors. Development of autoimmune-like disease was observed in mice lacking IRF-2, which is an attenuator of IFN-a/β signaling. Further analyses revealed the role of IFN-α/β signaling in the regulation of CD8^+ T cell response. In these IRF-2-deficient mice, such hyperactivation of IFN-α/β signaling affects normal differentiation of dendritic cells. IFN-α/β signaling is also found to be indispensable during DC maturation. Furthermore, it was demonstrated that another IRF-family member, IRF-7, is an essential transcriptional factor for the IFN induction in plasmacytoid DCs in response to unmethylated DNA (CpG), which is known to be a potent adjuvant for anti-tumor immunity. And we found a spaciotemporal regulation, by which plasmacytoid DCs are capable to produce IFN-α/β at high levels. On the other hand, IRF-5 is also found to be essentially involved in the CpG-induced production of proinflammatory cytokines. In addition, we identified novel p53 target genes, Noxa and Reprimo, which are involved in p53-mediated apoptosis or cell cycle arrest, respectively. Further study by generating Noxa-deficient mice revealed that Noxa may be a beneficial therapeutic target since it undergoes selective apoptosis in oncogene-expressing cells. Finally, we found an interrelationship between IFN-α/β signaling and p53-mediated response, which provided a novel aspect in terms of a linkage between tumor suppression and immunity. Taken together, we believe that these research accomplishments contribute to some advance in understanding molecular mechanisms underlying tumor suppression, and provide a molecular basis for their clinical applications.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2003 -2003 
    Author : 高岡 晃教, 本田 賢也
     
    本年度,抗ウイルス免疫応答系においてIFNとp53との新しい関連性を報告した.癌抑制因子であるp53の遺伝子がIFN-α/βによって発現誘導されることを見出した.また,p53はウイルス感染によってリン酸化され,活性化されることも明らかにした.p53欠損細胞では水庖性口内炎ウイルス(VSV)感染によるアポトーシスが阻害され,結果的には上清中のウイルス産生のレベルが野生型細胞の場合と比較して著明に高くなる結果を得た.更にP53欠損マウスが野生型マウスに比べ,VSVに対して感受性であり,また,ウイルスが過剰に増殖し,死亡に至る割合が高いことが見出された.さらに,IFNAR1欠損細胞を用いた解析より,ウイルス感染により産生されるIFN-α/βによって誘導されたp53も同様の役割を担っていることが示された.即ち,ウイルスによって活性化されたp53は感染細胞を迅速かつ効率のよい細胞死をもたらすことによってウイルスの複製や周囲への拡散を抑制することに寄与していると考えられた.一方,IFN-α/βはウイルスのみならず様々な病原体関連分子により樹状細胞において発現が誘導され,樹状細胞の成熟・活性化に重要な役割を担っていることも明らかにした.即ち,マクロファージや樹状細胞においてLPSや二本鎖RNA刺激によりIFN-α/β遺伝子の発現誘導が認められ,その誘導にIRF-3やIRF-7が関与しているという結果を得た.また,ウイルス感染時における樹状細胞の活性化はIFN-α/β依存性であることも見出した.二本鎖RNAの認識受容体であるTLR3とPKRの発現誘導がIFN-α/βにより転写レベルで制御されていることも明らかにした.更に,IFN-α/βはTLR3,PKRのみならず,それ以外にもウイルス認識に関わる分子群の誘導に関わっているという結果をTLR3,PKR欠損マウスを用いた検討から明らかにした.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2002 -2002 
    Author : 高岡 晃教, 本田 賢也
     
    インターフェロン(IFN)-α/βによるToll-like receptors (TLRs)シグナルの増幅を介した,樹状細胞活性化に関わる新たな機構を明らかにした、TLRsは,病原体由来のPAMPs (pathogen-associated molecular patterns)を認識する生体側の受容体として知られているが,TLRを介するシグナルは,樹状細胞の二次リンパ組織のT細胞領域への移入並びに,成熟を促すことが知られている.中でもTLR3は,ウイルス関連分子の二本鎖RNAを認識することにより,効率的な抗ウイルス応答を誘導する重要な役割を担っていると考えられている.我々は,このTLR3が,自然免疫系において中心的な役割を持つIFN-α/βにより,mRNAレベルで誘導されることで,TLR3を介するシグナル伝達系が増幅されることを見出した.実際に,樹状細胞において,二本鎖RNAによる二相性の活性化メカニズムが存在することが示された.すなわち,初期では,二本鎖RNAによってIFN遺伝子が誘導される.後期では,初期で誘導されたIFN-α/βを介したシグナルによって,TLR3の発現が引き起こされることにより,TLR3シグナルの増幅へとつながることが明らかになった.IFN-α/βシグナルの入らないIFN受容体欠損(IFNAR1^<-/->)マウスでは,二本鎖RNAに対する樹状細胞の成熟障害が認められるが,興味深いことに,このIFNAR1^<-/->マウス由来の樹状細胞にTLR3のみを発現させることにより,その成熟障害が回復した.さらに我々は,IFNAR1^<-/->マウスにおいては,樹状細胞における二本鎖RNAあるいはRNAウイルスに対する成熟応答が認められないものの,T細胞領域への移入は正常に起こることも見出した.つまり,樹状細胞の二次リンパ組織への移動と成熟は異なるメカニズムによって制御されていることも明らかにした. 以上の結果より,本研究では,IFN-α/βによるTLR3シグナルの増幅系により,樹状細胞での二本鎖RNAによる二相性の活性化メカニズムが存在することを明らかにした.このようにIFN-α/βを介するTLR3シグナルの増幅は,ウイルスに対する免疫応答をより高めるために生体が獲得した制御機構であると考えられ,さらにこのことは,自然免疫系と適応免疫系との新たな連携機構の存在を示唆している.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2001 -2002 
    Author : TAKAOKA Akinori, TANAKA Nobuyuki
     
    Cross talk between distinct receptor components is often important to amplify, suppress or modulate a given receptor signalling pathway by the other, and this is an aspect critical to generate diversity of cellular responses. In this study, we sought to explore a novel regulatory mechanism(s) in cytokine signal transduction, particularly in terms of the possible involvement of membrane domains in signalling efficiency, specificity and cross talk among cytokine signallings. In this context, we previously reported on the critical role of the IFN-α/β signalling complex, generated by constitutively produced IFN-α/(3, in IFN-γ signalling. As a result of the extended study, here, we found a novel cross talk between interferon (IFN)-α/β and interleukin (IL)-6 signallings, wherein the constitutive, weak IFN-α/β signalling also contributes to enhance the IL-6 signalling. The previous and present studies showed that the receptor components for IFN-α/β, IFN-γ, and IL-6 were concentrated in caveolar membrane fractions, i.e., membrane domains. This suggests that these receptor components seem to be in close proximity to forma mulli-subunit complex, which may be termed "receptosome", so as to make efficient signalling for these cytokines. In addition, these results show a possibility that these membrane domains play a role as a signalling scaffold for these receptor components during the cytokine signalling. Through these series of studies, we demonstrated a unique facet of a weak signalling by IFN-α/β, which is constitutively produced at a low level in the absence of viral infection. In fact, we additionally found that this weak signal also contributes to amplification of IFN-α/β production in response to viral infection. Therefore, this weak signalling, described in the context of what we propose as a "revving-up system", was found to provide a foundation for a more efficient and robust signalling in host defense. We also showed the possible role of the constitutive, weak IFN-α/β signalling in suppression of oncogenesis, in terms of a unique tumor urveillance system. Furthermore, we found a novel inter-relationship between IFN-α/β signalling and p53 response in tumor suppression, which may provide a possible underlying mechanism to the direct effect of IFN in tumor suppression. Taken together, we believe that these research accomplishments made progress in the study on the elucidation of advanced complex mechanisms for the regulation of cellular signalling events, and that further extended studies will provide any contributions not only to the elucidation of underlying signalling aspects which cause cancer or autoimmune diseases, but to their therapeutic applications
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2001 -2001 
    Author : 芫岡 晃教, 本田 賢也
     
    IRF (interferon regulatory factor)-7遺伝子欠損マウスを作製し,このマウス由来の胎仔線維芽細胞(MEF)を用いて,ウイルス感染時におけるinterferon (IFN)産生について検討を行った.Northern blottingの結果,IFN-αのmRNAの誘導が全く認められず,IFN-βのmRNAの発現も著明に減弱していた.同様の結果が,IRF-7遺伝子欠損マウスの脾細胞についても得られた.以上の結果より,IRF-7を介したpositive feedbackメカニズムの重要性が確証された. 次に,樹状細胞の活性化におけるIFN-IRF系の役割について分子レベルで検討した.樹状細胞は,骨髄細胞をGM-CSF存在下で6日間培養した後,MACSでCD11c陽性細胞のみをsortして得られたものを用いた.その結果,IFN-βが,pathogen-associated molecules (PAMs)である,lipopolysaccharide (LPS)やdouble strand RNA (dsRNA),非メチル化DNAのCpGによっても,誘導されることが示された.しかしながら,IFN-αの誘導はpolyI : C刺激時においてのみ認めた.IRF-3遺伝子欠損マウス由来の樹状細胞においては,LPSやpolyI : C刺激後においてIFN-βの発現が著明に低下していたが,CpG刺激後においてはわずかに低下を認めるのみであった.一方IRF-7遺伝子欠損マウス由来の樹状細胞においては,polyI : C刺激後のIFN-βの発現誘導は減弱したが,LPS刺激後においてはあまり変化を認めなかった.さらに,IFNAR1遺伝子欠損マウス由来の樹状細胞においては,polyI : C刺激後,MHC class IIのupregulationは正常に起こるが,MHC class Iやcostimulatory moleculesのupregulationがおこらず,またallo stimulatory activityも特にCD8T細胞に対して著しく低下していた.しかしながら,PAMs刺激後共通に起こることではなく,LPSやCpG刺激後allo stimulatory activityにおいて,IFNAR1遺伝子欠損マウスと野生型マウス間においてpolyI : C刺激時のような著明な差は認められなかった.以上の結果より,PAMs刺激において,樹状細胞はToll-like receptorを介して様々なeffector分子とともに,IFNを誘導し,その誘導には,IRF-3/7が関与していることが示されたが,ウイルス感染とは異なったシグナルカスケードが関与していることが示唆された.また,特にdsRNA刺激を受けた樹状細胞において,IFN-α/βによってCD8+T細胞の応答をより増強する方向に働くことも示唆された.

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