TRAF4 functions as an intermediate of GITR-induced NF-kappaB activation.
Members of the tumor necrosis factor receptor (TNFR) family regulate the activation, differentiation, and function of many cell types, including cells of the immune system. TNFR-associated factors (TRAFs) function as adapter molecules controlling signaling pathways triggered by TNFR family members, such as activation of nuclear factor kappaB (NF-kappaB). Despite intensive research, the function of TRAF4 in signaling pathways triggered by TNFR-related proteins remains enigmatic. Intriguingly, our functional studies indicated that TRAF4 augments NF-kappaB activation triggered by glucocorticoid-induced TNFR (GITR), a receptor expressed on T cells, B cells, and macrophages. Further analyses revealed that TRAF4-mediated NF-kappaB activation downstream of GITR depends on a previously mapped TRAF-binding site in the cytoplasmic domain of the receptor and is inhibited by the cytoplasmic protein A20. GITR is thought to inhibit the suppressive function of regulatory T cells (Treg cells) and to promote activation of T cells. Taken together, our studies provide the first indications that TRAF4 elaborates GITR signaling and suggest that TRAF4 can modulate the suppressive functions of Treg cells.
Esparza
E M
EM
School of Medicine, Departments of Medicine and Pathology and Immunology, Washington University, 660 S. Euclid Avenue, Campus Box 8052, Saint Louis, Missouri 63110, USA.
Arch
R H
RH
D001665:Binding Sites; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism*; D009687:Nuclear Proteins; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D047992:TNF Receptor-Associated Factor 2 / Q000235:genetics / Q000378:metabolism; D053449:TNF Receptor-Associated Factor 4; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3
D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D011506:Proteins; D017475:Receptors, Nerve Growth Factor; D047992:TNF Receptor-Associated Factor 2; D053449:TNF Receptor-Associated Factor 4; C506367:TRAF4 protein, human; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3