Abstract
Toll-like receptor 4 (TLR4) induces two distinct signaling pathways controlled by the TIRAP-MyD88 and TRAM-TRIF pairs of adaptor proteins, which elicit the production of proinflammatory cytokines and type I interferons, respectively. How TLR4 coordinates the activation of these two pathways is unknown. Here we show that TLR4 activated these two signaling pathways sequentially in a process organized around endocytosis of the TLR4 complex. We propose that TLR4 first induces TIRAP-MyD88 signaling at the plasma membrane and is then endocytosed and activates TRAM-TRIF signaling from early endosomes. Our data emphasize a unifying theme in innate immune recognition whereby all type I interferon–inducing receptors signal from an intracellular location.
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References
- 1
Akira, S., Uematsu, S. & Takeuchi, O. Pathogen recognition and innate immunity. Cell 124, 783–801 (2006).
- 2
Janeway, C.A. Jr & Medzhitov, R. Innate immune recognition. Annu. Rev. Immunol. 20, 197–216 (2002).
- 3
Hirotani, T. et al. Regulation of lipopolysaccharide-inducible genes by MyD88 and Toll/IL-1 domain containing adaptor inducing IFN-β. Biochem. Biophys. Res. Commun. 328, 383–392 (2005).
- 4
Yamamoto, M. et al. Role of adaptor TRIF in the MyD88-independent Toll-like receptor signaling pathway. Science 301, 640–643 (2003).
- 5
Yamamoto, M. et al. TRAM is specifically involved in the Toll-like receptor 4-mediated MyD88-independent signaling pathway. Nat. Immunol. 4, 1144–1150 (2003).
- 6
Yamamoto, M. et al. Essential role for TIRAP in activation of the signalling cascade shared by TLR2 and TLR4. Nature 420, 324–329 (2002).
- 7
Horng, T., Barton, G.M., Flavell, R.A. & Medzhitov, R. The adaptor molecule TIRAP provides signalling specificity for Toll-like receptors. Nature 420, 329–333 (2002).
- 8
Barton, G.M., Kagan, J.C. & Medzhitov, R. Intracellular localization of Toll-like receptor 9 prevents recognition of self DNA but facilitates access to viral DNA. Nat. Immunol. 7, 49–56 (2006).
- 9
Latz, E. et al. TLR9 signals after translocating from the ER to CpG DNA in the lysosome. Nat. Immunol. 5, 190–198 (2004).
- 10
Hayashi, F. et al. The innate immune response to bacterial flagellin is mediated by Toll-like receptor 5. Nature 410, 1099–1103 (2001).
- 11
Toshchakov, V. et al. TLR4, but not TLR2, mediates IFN-β-induced STAT1α/β-dependent gene expression in macrophages. Nat. Immunol. 3, 392–398 (2002).
- 12
Alexopoulou, L., Holt, A.C., Medzhitov, R. & Flavell, R.A. Recognition of double-stranded RNA and activation of NF-κB by Toll-like receptor 3. Nature 413, 732–738 (2001).
- 13
Lund, J.M. et al. Recognition of single-stranded RNA viruses by Toll-like receptor 7. Proc. Natl. Acad. Sci. USA 101, 5598–5603 (2004).
- 14
Diebold, S.S., Kaisho, T., Hemmi, H., Akira, S. & Reis e Sousa, C. Innate antiviral responses by means of TLR7-mediated recognition of single-stranded RNA. Science 303, 1529–1531 (2004).
- 15
Kawai, T. & Akira, S. Antiviral signaling through pattern recognition receptors. J. Biochem. 141, 137–145 (2007).
- 16
Honda, K. et al. IRF-7 is the master regulator of type-I interferon-dependent immune responses. Nature 434, 772–777 (2005).
- 17
Kawai, T. et al. Interferon-α induction through Toll-like receptors involves a direct interaction of IRF7 with MyD88 and TRAF6. Nat. Immunol. 5, 1061–1068 (2004).
- 18
Doyle, S. et al. IRF3 mediates a TLR3/TLR4-specific antiviral gene program. Immunity 17, 251–263 (2002).
- 19
Oshiumi, H., Matsumoto, M., Funami, K., Akazawa, T. & Seya, T. TICAM-1, an adaptor molecule that participates in Toll-like receptor 3-mediated interferon-β induction. Nat. Immunol. 4, 161–167 (2003).
- 20
Barton, G.M. & Medzhitov, R. Toll-like receptor signaling pathways. Science 300, 1524–1525 (2003).
- 21
Takaoka, A. et al. DAI (DLM-1/ZBP1) is a cytosolic DNA sensor and an activator of innate immune response. Nature 448, 501–505 (2007).
- 22
Kato, H. et al. Differential roles of MDA5 and RIG-I helicases in the recognition of RNA viruses. Nature 441, 101–105 (2006).
- 23
O'Neill, L.A. & Bowie, A.G. The family of five: TIR-domain-containing adaptors in Toll-like receptor signalling. Nat. Rev. Immunol. 7, 353–364 (2007).
- 24
Kagan, J.C. & Medzhitov, R. Phosphoinositide-mediated adaptor recruitment controls Toll-like receptor signaling. Cell 125, 943–955 (2006).
- 25
Ulrichts, P., Peelman, F., Beyaert, R. & Tavernier, J. MAPPIT analysis of TLR adaptor complexes. FEBS Lett. 581, 629–636 (2007).
- 26
Oshiumi, H. et al. TIR-containing adapter molecule (TICAM)-2, a bridging adapter recruiting to toll-like receptor 4 TICAM-1 that induces interferon-β. J. Biol. Chem. 278, 49751–49762 (2003).
- 27
Rowe, D.C. et al. The myristoylation of TRIF-related adaptor molecule is essential for Toll-like receptor 4 signal transduction. Proc. Natl. Acad. Sci. USA 103, 6299–6304 (2006).
- 28
Husebye, H. et al. Endocytic pathways regulate Toll-like receptor 4 signaling and link innate and adaptive immunity. EMBO J. 25, 683–692 (2006).
- 29
Praefcke, G.J. & McMahon, H.T. The dynamin superfamily: universal membrane tubulation and fission molecules? Nat. Rev. Mol. Cell Biol. 5, 133–147 (2004).
- 30
Akashi, S. et al. Lipopolysaccharide interaction with cell surface Toll-like receptor 4-MD-2: higher affinity than that with MD-2 or CD14. J. Exp. Med. 198, 1035–1042 (2003).
- 31
Macia, E. et al. Dynasore, a cell-permeable inhibitor of dynamin. Dev. Cell 10, 839–850 (2006).
- 32
Boll, W., Ehrlich, M., Collier, R.J. & Kirchhausen, T. Effects of dynamin inactivation on pathways of anthrax toxin uptake. Eur. J. Cell Biol. 83, 281–288 (2004).
- 33
Damke, H., Baba, T., van der Bliek, A.M. & Schmid, S.L. Clathrin-independent pinocytosis is induced in cells overexpressing a temperature-sensitive mutant of dynamin. J. Cell Biol. 131, 69–80 (1995).
- 34
Seeger, M. & Payne, G.S. A role for clathrin in the sorting of vacuolar proteins in the Golgi complex of yeast. EMBO J. 11, 2811–2818 (1992).
- 35
Racoosin, E.L. & Swanson, J.A. Macropinosome maturation and fusion with tubular lysosomes in macrophages. J. Cell Biol. 121, 1011–1020 (1993).
- 36
Radhakrishna, H. & Donaldson, J.G. ADP-ribosylation factor 6 regulates a novel plasma membrane recycling pathway. J. Cell Biol. 139, 49–61 (1997).
- 37
McDonald, P.H. et al. β-arrestin 2: a receptor-regulated MAPK scaffold for the activation of JNK3. Science 290, 1574–1577 (2000).
- 38
Sandilands, E., Brunton, V.G. & Frame, M.C. The membrane targeting and spatial activation of Src, Yes and Fyn is influenced by palmitoylation and distinct RhoB/RhoD endosome requirements. J. Cell Sci. 120, 2555–2564 (2007).
- 39
Martin, T.F. Phosphoinositide lipids as signaling molecules: common themes for signal transduction, cytoskeletal regulation, and membrane trafficking. Annu. Rev. Cell Dev. Biol. 14, 231–264 (1998).
- 40
Oganesyan, G. et al. Critical role of TRAF3 in the Toll-like receptor-dependent and -independent antiviral response. Nature 439, 208–211 (2006).
- 41
Hacker, H. et al. Specificity in Toll-like receptor signalling through distinct effector functions of TRAF3 and TRAF6. Nature 439, 204–207 (2006).
- 42
Rothe, M., Sarma, V., Dixit, V.M. & Goeddel, D.V. TRAF2-mediated activation of NF-κB by TNF receptor 2 and CD40. Science 269, 1424–1427 (1995).
- 43
Botelho, R.J. et al. Localized biphasic changes in phosphatidylinositol-4,5-bisphosphate at sites of phagocytosis. J. Cell Biol. 151, 1353–1368 (2000).
- 44
Nunez Miguel, R. et al. A dimer of the Toll-like receptor 4 cytoplasmic domain provides a specific scaffold for the recruitment of signalling adaptor proteins. PLoS ONE 2, e788 (2007).
- 45
Vieira, A.V., Lamaze, C. & Schmid, S.L. Control of EGF receptor signaling by clathrin-mediated endocytosis. Science 274, 2086–2089 (1996).
- 46
Schneider-Brachert, W. et al. Compartmentalization of TNF receptor 1 signaling: internalized TNF receptosomes as death signaling vesicles. Immunity 21, 415–428 (2004).
- 47
Xu, Y., Cheng, G. & Baltimore, D. Targeted disruption of TRAF3 leads to postnatal lethality and defective T-dependent immune responses. Immunity 5, 407–415 (1996).
- 48
Hostager, B.S., Catlett, I.M. & Bishop, G.A. Recruitment of CD40 and tumor necrosis factor receptor-associated factors 2 and 3 to membrane microdomains during CD40 signaling. J. Biol. Chem. 275, 15392–15398 (2000).
- 49
Kagan, J.C. & Roy, C.R. Legionella phagosomes intercept vesicular traffic from endoplasmic reticulum exit sites. Nat. Cell Biol. 4, 945–954 (2002).
- 50
Horng, T., Barton, G.M. & Medzhitov, R. TIRAP: an adapter molecule in the Toll signaling pathway. Nat. Immunol. 2, 835–841 (2001).
Acknowledgements
We thank K. Miyake (Institute for Medical Sciences, University of Toyko) for Sa15-21; S. Akira (Osaka University) for TRAM-KO mice; C. Roy (Yale University) for Rab5 plasmids; T. Kirchhausen (Immune Disease Institute and Harvard Medical School) for dynasore; L. Marek, D. Hargreaves and C. Sokol for discussions; and T. Medjitov for help with bioinformatics analysis. Supported by the National Institutes of Health (1K99AI072955-01 to J.C.K., and R37 AI046688, P01 AI44220 and AI 061360 to R.M.) and the Howard Hughes Medical Institute (R.M.).
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Kagan, J., Su, T., Horng, T. et al. TRAM couples endocytosis of Toll-like receptor 4 to the induction of interferon-β. Nat Immunol 9, 361–368 (2008). https://doi.org/10.1038/ni1569
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