| Structural highlights
Function
[TCAM2_HUMAN] Functions as sorting adapter in LPS-TLR4 signaling to regulate the MYD88-independent pathway during the innate immune response to LPS. Physically bridges TLR4 and TICAM1 and functionally transmits LPS-TRL4 signal to TICAM1; signaling is proposed to occur in early endosomes after endocytosis of TLR4. May also be involved in IL1-triggered NF-kappa-B activation, functioning upstream of IRAK1, IRAK2, TRAF6, and IKBKB; however, reports are controversial. Involved in IL-18 signaling and is proposed to function as a sorting adaptor for MYD88 in IL-18 signaling during adaptive immune response.[1] [2] [3] [4] [5] [6] [7] Isoform 2: Proposed to inhibit LPS-TLR4 signaling at the late endosome by interaction with isoform 1 thereby disrupting the association of isoform 1 with TICAM1. May be involved in TLR4 degradation in late endosomes.[8] [9] [10] [11] [12] [13] [14]
Publication Abstract from PubMed
Homotypic and heterotypic interactions between Toll/interleukin-1 receptor (TIR) domains in Toll-like receptors (TLRs) and downstream adaptors are essential to evoke innate immune responses. However, such oligomerization properties present intrinsic difficulties in structural studies of TIR domains. Here, using BB-loop mutations that disrupt homotypic interactions, we determined the structures of the monomeric TIR domain-containing adaptor molecule (TICAM)-1 and TICAM-2 TIR domains. Docking of the monomeric structures, together with yeast two hybrid-based mutagenesis assays, reveals that the homotypic interaction between TICAM-2 TIR is indispensable to present a scaffold for recruiting the monomeric moiety of the TICAM-1 TIR dimer. This result proposes a unique idea that oligomerization of upstream TIR domains is crucial for binding of downstream TIR domains. Furthermore, the bivalent nature of each TIR domain dimer can generate a large signaling complex under the activated TLRs, which would recruit downstream signaling molecules efficiently. This model is consistent with previous reports that BB-loop mutants completely abrogate downstream signaling.
Structures and interface mapping of the TIR domain-containing adaptor molecules involved in interferon signaling.,Enokizono Y, Kumeta H, Funami K, Horiuchi M, Sarmiento J, Yamashita K, Standley DM, Matsumoto M, Seya T, Inagaki F Proc Natl Acad Sci U S A. 2013 Dec 3;110(49):19908-13. doi:, 10.1073/pnas.1222811110. Epub 2013 Nov 19. PMID:24255114[15]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Bin LH, Xu LG, Shu HB. TIRP, a novel Toll/interleukin-1 receptor (TIR) domain-containing adapter protein involved in TIR signaling. J Biol Chem. 2003 Jul 4;278(27):24526-32. Epub 2003 Apr 28. PMID:12721283 doi:http://dx.doi.org/10.1074/jbc.M303451200
- ↑ Oshiumi H, Sasai M, Shida K, Fujita T, Matsumoto M, Seya T. TIR-containing adapter molecule (TICAM)-2, a bridging adapter recruiting to toll-like receptor 4 TICAM-1 that induces interferon-beta. J Biol Chem. 2003 Dec 12;278(50):49751-62. Epub 2003 Sep 30. PMID:14519765 doi:http://dx.doi.org/10.1074/jbc.M305820200
- ↑ Fitzgerald KA, Rowe DC, Barnes BJ, Caffrey DR, Visintin A, Latz E, Monks B, Pitha PM, Golenbock DT. LPS-TLR4 signaling to IRF-3/7 and NF-kappaB involves the toll adapters TRAM and TRIF. J Exp Med. 2003 Oct 6;198(7):1043-55. Epub 2003 Sep 29. PMID:14517278 doi:http://dx.doi.org/10.1084/jem.20031023
- ↑ . PMID:194121844
- ↑ Rowe DC, McGettrick AF, Latz E, Monks BG, Gay NJ, Yamamoto M, Akira S, O'Neill LA, Fitzgerald KA, Golenbock DT. The myristoylation of TRIF-related adaptor molecule is essential for Toll-like receptor 4 signal transduction. Proc Natl Acad Sci U S A. 2006 Apr 18;103(16):6299-304. Epub 2006 Apr 7. PMID:16603631 doi:http://dx.doi.org/10.1073/pnas.0510041103
- ↑ McGettrick AF, Brint EK, Palsson-McDermott EM, Rowe DC, Golenbock DT, Gay NJ, Fitzgerald KA, O'Neill LA. Trif-related adapter molecule is phosphorylated by PKC{epsilon} during Toll-like receptor 4 signaling. Proc Natl Acad Sci U S A. 2006 Jun 13;103(24):9196-201. Epub 2006 Jun 6. PMID:16757566 doi:http://dx.doi.org/10.1073/pnas.0600462103
- ↑ Ohnishi H, Tochio H, Kato Z, Kawamoto N, Kimura T, Kubota K, Yamamoto T, Funasaka T, Nakano H, Wong RW, Shirakawa M, Kondo N. TRAM is involved in IL-18 signaling and functions as a sorting adaptor for MyD88. PLoS One. 2012;7(6):e38423. doi: 10.1371/journal.pone.0038423. Epub 2012 Jun 7. PMID:22685567 doi:http://dx.doi.org/10.1371/journal.pone.0038423
- ↑ Bin LH, Xu LG, Shu HB. TIRP, a novel Toll/interleukin-1 receptor (TIR) domain-containing adapter protein involved in TIR signaling. J Biol Chem. 2003 Jul 4;278(27):24526-32. Epub 2003 Apr 28. PMID:12721283 doi:http://dx.doi.org/10.1074/jbc.M303451200
- ↑ Oshiumi H, Sasai M, Shida K, Fujita T, Matsumoto M, Seya T. TIR-containing adapter molecule (TICAM)-2, a bridging adapter recruiting to toll-like receptor 4 TICAM-1 that induces interferon-beta. J Biol Chem. 2003 Dec 12;278(50):49751-62. Epub 2003 Sep 30. PMID:14519765 doi:http://dx.doi.org/10.1074/jbc.M305820200
- ↑ Fitzgerald KA, Rowe DC, Barnes BJ, Caffrey DR, Visintin A, Latz E, Monks B, Pitha PM, Golenbock DT. LPS-TLR4 signaling to IRF-3/7 and NF-kappaB involves the toll adapters TRAM and TRIF. J Exp Med. 2003 Oct 6;198(7):1043-55. Epub 2003 Sep 29. PMID:14517278 doi:http://dx.doi.org/10.1084/jem.20031023
- ↑ . PMID:194121844
- ↑ Rowe DC, McGettrick AF, Latz E, Monks BG, Gay NJ, Yamamoto M, Akira S, O'Neill LA, Fitzgerald KA, Golenbock DT. The myristoylation of TRIF-related adaptor molecule is essential for Toll-like receptor 4 signal transduction. Proc Natl Acad Sci U S A. 2006 Apr 18;103(16):6299-304. Epub 2006 Apr 7. PMID:16603631 doi:http://dx.doi.org/10.1073/pnas.0510041103
- ↑ McGettrick AF, Brint EK, Palsson-McDermott EM, Rowe DC, Golenbock DT, Gay NJ, Fitzgerald KA, O'Neill LA. Trif-related adapter molecule is phosphorylated by PKC{epsilon} during Toll-like receptor 4 signaling. Proc Natl Acad Sci U S A. 2006 Jun 13;103(24):9196-201. Epub 2006 Jun 6. PMID:16757566 doi:http://dx.doi.org/10.1073/pnas.0600462103
- ↑ Ohnishi H, Tochio H, Kato Z, Kawamoto N, Kimura T, Kubota K, Yamamoto T, Funasaka T, Nakano H, Wong RW, Shirakawa M, Kondo N. TRAM is involved in IL-18 signaling and functions as a sorting adaptor for MyD88. PLoS One. 2012;7(6):e38423. doi: 10.1371/journal.pone.0038423. Epub 2012 Jun 7. PMID:22685567 doi:http://dx.doi.org/10.1371/journal.pone.0038423
- ↑ Enokizono Y, Kumeta H, Funami K, Horiuchi M, Sarmiento J, Yamashita K, Standley DM, Matsumoto M, Seya T, Inagaki F. Structures and interface mapping of the TIR domain-containing adaptor molecules involved in interferon signaling. Proc Natl Acad Sci U S A. 2013 Dec 3;110(49):19908-13. doi:, 10.1073/pnas.1222811110. Epub 2013 Nov 19. PMID:24255114 doi:http://dx.doi.org/10.1073/pnas.1222811110
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