Identification of TRAF6, a novel tumor necrosis factor receptor-associated factor protein that mediates signaling from an amino-terminal domain of the CD40 cytoplasmic region.
CD40 signalings play crucial roles in B-cell function. To identify molecules which transduce CD40 signalings, we have utilized the yeast two-hybrid system to clone cDNAs encoding proteins that bind the cytoplasmic tail of CD40. A cDNA encoding a putative signal transducer, designated TRAF6, has been molecularly cloned. TRAF6 has a tumor necrosis factor receptor (TNFR)-associated factor (TRAF) domain in its carboxyl terminus and has a RING finger domain, a cluster of zinc fingers and a coiled-coil domain, which are also present in other TRAF family proteins. TRAF6 does not associate with the cytoplasmic tails of TNFR2, CD30, lymphotoxin-beta receptor, and LMP1 of Epstein-Barr virus. Deletion analysis showed that residues 246-269 of CD40 which are required for its association with TRAF2, TRAF3, and TRAF5 are dispensable for its interaction with TRAF6, whereas residues 230-245 were required. Overexpression of TRAF6 activates transcription factor NFkappaB, and its TRAF-C domain suppresses NFkappaB activation triggered by CD40 lacking residues 246-277. These results suggest that TRAF6 could mediate the CD40 signal that is transduced by the amino-terminal domain (230-245) of the CD40 cytoplasmic region and appears to be independent of other known TRAF family proteins.
Ishida
T
T
Department of Oncology, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108, Japan. jinoue@imsut.u-tokyo.ac.jp
Mizushima
S i
Si
Azuma
S
S
Kobayashi
N
N
Tojo
T
T
Suzuki
K
K
Aizawa
S
S
Watanabe
T
T
Mosialos
G
G
Kieff
E
E
Yamamoto
T
T
Inoue
J
J
D000595:Amino Acid Sequence; D000818:Animals; D019013:CD40 Antigens / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D018076:DNA, Complementary; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins; D015398:Signal Transduction; D048029:TNF Receptor-Associated Factor 6; D014407:Tumor Cells, Cultured
D019013:CD40 Antigens; D002352:Carrier Proteins; D018076:DNA, Complementary; D016328:NF-kappa B; D011506:Proteins; D048029:TNF Receptor-Associated Factor 6