LPS-TLR4 signaling to IRF-3/7 and NF-kappaB involves the toll adapters TRAM and TRIF.
Toll-IL-1-resistance (TIR) domain-containing adaptor-inducing IFN-beta (TRIF)-related adaptor molecule (TRAM) is the fourth TIR domain-containing adaptor protein to be described that participates in Toll receptor signaling. Like TRIF, TRAM activates interferon regulatory factor (IRF)-3, IRF-7, and NF-kappaB-dependent signaling pathways. Toll-like receptor (TLR)3 and 4 activate these pathways to induce IFN-alpha/beta, regulated on activation, normal T cell expressed and secreted (RANTES), and gamma interferon-inducible protein 10 (IP-10) expression independently of the adaptor protein myeloid differentiation factor 88 (MyD88). Dominant negative and siRNA studies performed here demonstrate that TRIF functions downstream of both the TLR3 (dsRNA) and TLR4 (LPS) signaling pathways, whereas the function of TRAM is restricted to the TLR4 pathway. TRAM interacts with TRIF, MyD88 adaptor-like protein (Mal)/TIRAP, and TLR4 but not with TLR3. These studies suggest that TRIF and TRAM both function in LPS-TLR4 signaling to regulate the MyD88-independent pathway during the innate immune response to LPS.
D033942:Adaptor Proteins, Vesicular Transport / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D018946:Chemokine CCL5 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D006801:Humans; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000502:physiology*; D012330:RNA, Double-Stranded / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014157:Transcription Factors / Q000502:physiology*
D033942:Adaptor Proteins, Vesicular Transport; D018946:Chemokine CCL5; D004268:DNA-Binding Proteins; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014157:Transcription Factors; C494232:IRF3 protein, human; C494234:IRF7 protein, human; C494233:Irf3 protein, mouse; C494235:Irf7 protein, mouse; C476286:Ticam1 protein, mouse; C470409:TICAM1 protein, human; C495344:TLR3 protein, human; C495345:TLR4 protein, human