A novel Zinc finger protein, ZCCHC11, interacts with TIFA and modulates TLR signaling.
Toll-like receptors (TLRs) play an important role as a sensor of microbial pathogens in the innate immune response. TLRs transmit signals through the recruitment of adaptor proteins including tumor necrosis factor-associated factor 6 (TRAF6), which mediates the activation of IkappaB kinase (IKK). TIFA (TRAF-interacting protein with a forkhead-associated (FHA) domain) has been shown to bind to TRAF6 and activate IKK by promoting the oligomerization and ubiquitin-ligase activity of TRAF6. FHA domains preferentially bind to phospho-threonine residues in their targets. Here, we identified a novel zinc finger protein, ZCCHC11, that interacts with TIFA from phosphoproteins of a macrophage cell line, RAW 264.7, by using affinity purification with GST-TIFA and mass spectrometric analysis. By a search of the EST database, we found a 200kDa full-length form (ZCCHC11L). ZCCHC11L was mostly located to the nucleus, but translocated into the cytoplasm in response to LPS and bound to TIFA. Overexpression and knockdown by siRNA indicated that ZCCHC11 functions as a negative regulator of TLR-mediated NF-kappaB activation. The N-terminal region (ZCCHC11S) including C2H2-type [corrected] Zn-finger motif was sufficient for suppression of NF-kappaB. We propose that ZCCHC11 is a unique TLR signal regulator, which interacts with TIFA after LPS treatment and suppresses the TRAF6-dependent activation of NF-kappaB.
Minoda
Yasumasa
Y
Division of Molecular and Cellular Immunology, The Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi, Fukuoka 812-8582, Japan.
Saeki
Kazuko
K
Aki
Daisuke
D
Takaki
Hiromi
H
Sanada
Takahito
T
Koga
Keiko
K
Kobayashi
Takashi
T
Takaesu
Giichi
G
Yoshimura
Akihiko
A
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D015398:Signal Transduction / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism*; D051193:Toll-Like Receptors / Q000378:metabolism*; D016335:Zinc Fingers / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C499176:T2bp protein, mouse; C446759:TIFA protein, human; C511130:TUT4 protein, human; D051193:Toll-Like Receptors; C511129:ZCCHC11 protein, mouse