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TRAM is specifically involved in the Toll-like receptor 4–mediated MyD88-independent signaling pathway

Nature Immunology volume 4, pages 1144–1150 (2003)Cite this article

Abstract

Recognition of pathogens by Toll-like receptors (TLRs) triggers innate immune responses through signaling pathways mediated by Toll–interleukin 1 receptor (TIR) domain–containing adaptors such as MyD88, TIRAP and TRIF. MyD88 is a common adaptor that is essential for proinflammatory cytokine production, whereas TRIF mediates the MyD88-independent pathway from TLR3 and TLR4. Here we have identified a fourth TIR domain–containing adaptor, TRIF-related adaptor molecule (TRAM), and analyzed its physiological function by gene targeting. TRAM-deficient mice showed defects in cytokine production in response to the TLR4 ligand, but not to other TLR ligands. TLR4- but not TLR3-mediated MyD88-independent interferon-β production and activation of signaling cascades were abolished in TRAM-deficient cells. Thus, TRAM provides specificity for the MyD88-independent component of TLR4 signaling.

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Figure 1: Cloning and characterization of human TRAM and targeted disruption of the gene encoding mouse TRAM.
Figure 2: IL-1-induced responses in TRAM-deficient cells.
Figure 3: Impaired TLR4-mediated cytokine production and B cell activation in TRAM-deficient mice.
Figure 4: Defects in TLR4-mediated MyD88-independent responses in TRAM-deficient mice.
Figure 5: TRAM-deficient cells lack TLR4-mediated MyD88-independent signal transduction.
Figure 6: Participation of TIR domain–containing adaptor molecules in TLR3 and TLR4 signaling pathways.

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Acknowledgements

We thank D. Golenbock and H. Tomizawa for providing the NF-κB reporter plasmid and R-848, respectively. We also thank T. Kawai, H. Sanjo and H. Kuwata for discussions; M. Hashimoto for secretarial assistance; N. Okita and N. Iwami for technical assistance; and P. Lee for critical reading of the manuscript. Supported by grants from Special Coordination Funds; the Ministry of Education, Culture, Sports, Science and Technology; Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists; The Uehara Memorial Foundation; The Naito Foundation; and The Junior Research Associate from RIKEN.

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Authors and Affiliations

  1. Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Osaka, Japan

    Masahiro Yamamoto, Hiroaki Hemmi, Satoshi Uematsu, Tsuneyasu Kaisho, Osamu Takeuchi, Kiyoshi Takeda & Shizuo Akira

  2. ERATO, Japan Science and Technology Corporation, 3-1 Yamada-oka, Suita, 565-0871, Osaka, Japan

    Shintaro Sato, Kiyoshi Takeda & Shizuo Akira

  3. RIKEN Research Center for Allergy and Immunology, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Kanagawa, Japan

    Katsuaki Hoshino & Tsuneyasu Kaisho

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Correspondence to Shizuo Akira.

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Supplementary information

Supplementary Fig. 1.

Anti-mTRAM specifically recognized mouse TRAM and human TRAM 293 cells were transfected with empty (5 μg), mTRAM (1 μg), hTRAM (1 μg), and MyD88 (5 μg) vectors. The total amount of DNA (5 μg) was kept constant by adding the empty vector. Cell lysates were immunoprecipitated (IP) with anti-Myc (9B11, Cell signaling), and immunoblotted (IB) with anti-mTRAM or anti-Myc (9E10, Santa Cruz). (PDF 128 kb)

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Yamamoto, M., Sato, S., Hemmi, H. et al. TRAM is specifically involved in the Toll-like receptor 4–mediated MyD88-independent signaling pathway. Nat Immunol 4, 1144–1150 (2003). https://doi.org/10.1038/ni986

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