TNF receptor-associated factor 6 is an essential mediator of CD40-activated proinflammatory pathways in monocytes and macrophages.
The interaction between CD40 and its ligand, CD154, has been shown to play a role in the onset and maintenance of inflammatory disease. Contributing to this process is the ability of CD40 to signal monocyte and macrophage inflammatory cytokine production. We have shown that this event is dependent on Src family tyrosine kinase activity and the subsequent activation of ERK1/2. To address the role of TNFR-associated factor (TRAF) family members in facilitating this signaling pathway, we transfected a CD40-deficient macrophage cell line with wild-type human CD40, or with CD40 containing disrupted TRAF binding sites. Ligation of either wild-type CD40, or a CD40 mutant unable to bind TRAF2/3/5, resulted in the stimulation of inflammatory cytokine production. However, ligation of a CD40 mutant lacking a functional TRAF6 binding site did not initiate inflammatory cytokine production, and this mutant was found to be defective in CD40-mediated activation of ERK1/2, as well as IkappaB kinase (IKK) and NF-kappaB. Likewise, introduction of a dominant-negative TRAF6 into a wild-type (CD40(+)) macrophage cell line resulted in abrogation of CD40-mediated induction of inflammatory cytokine synthesis. Finally, treatment of monocytes with a cell-permeable peptide corresponding to the TRAF6-binding motif of CD40 inhibited CD40 activation of ERK1/2, IKK, and inflammatory cytokine production. These data demonstrate that TRAF6 acts as a critical adapter of both the Src/ERK1/2 and IKK/NF-kappaB proinflammatory signaling pathways in monocytes and macrophages.
Mukundan
Lata
L
Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
Bishop
Gail A
GA
Head
Kimberly Z
KZ
Zhang
Lihua
L
Wahl
Larry M
LM
Suttles
Jill
J
D000595:Amino Acid Sequence; D001665:Binding Sites; D019013:CD40 Antigens / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002461:Cell Line, Transformed; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase; D018836:Inflammation Mediators / Q000378:metabolism / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology; D008264:Macrophages / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008969:Molecular Sequence Data; D009000:Monocytes / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009363:Neoplasm Proteins / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*; D047992:TNF Receptor-Associated Factor 2 / Q000235:genetics / Q000378:metabolism; D048008:TNF Receptor-Associated Factor 3 / Q000235:genetics / Q000378:metabolism; D048015:TNF Receptor-Associated Factor 5 / Q000235:genetics / Q000378:metabolism; D048029:TNF Receptor-Associated Factor 6 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019061:src-Family Kinases / Q000502:physiology
D019013:CD40 Antigens; D016207:Cytokines; D018836:Inflammation Mediators; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009363:Neoplasm Proteins; C120635:TAX1BP1 protein, human; D047992:TNF Receptor-Associated Factor 2; D048008:TNF Receptor-Associated Factor 3; D048015:TNF Receptor-Associated Factor 5; D048029:TNF Receptor-Associated Factor 6; D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3