TRAF-3 interacts with p62 nucleoporin, a component of the nuclear pore central plug that binds classical NLS-containing import complexes.
The TRAF-3 gene encodes a number of splice-variant isoforms that function as adapter molecules in NF-kappaB signaling, in part by associating with the cytoplasmic tails of CD40 or other TNF-receptor (TNF-R) family members. To identify downstream molecules in TRAF-3 signaling, a yeast two-hybrid library was screened with a full-length TRAF-3 construct. Nine independent TRAF-3 interacting clones encoded fragments of p62 Nucleoporin (p62), a 522 amino acid (aa) component of the nuclear pore central plug, that is known to bind karyopherin-beta/classical-NLS import factor complexes. The interaction of p62 with TRAF-3 was specific, since p62 failed to interact with TRAF-2, -4, -5, or -6. Deletional analysis in yeast revealed that the p62:TRAF-3 interaction is mediated by a p62 carboxy (C)-terminal coiled-coil domain and TRAF-3's fifth zinc (Zn) finger and coiled-coil domain. In human 293 T cells, recombinant TRAF-3 or p62 specifically co-immunoprecipitates the other species. In addition, endogenous p62 co-precipitates over-expressed TRAF-3. The functional effects of over-expressing a TRAF-3 binding fragment, p62(aa 336-522) were studied on NF-kappaB-dependent, or control STAT1-dependent reporter activity in 293 T cells, either resting or after stimulation by CD40 or IFN-gamma, respectively. Over-expression of p62(aa 336-522) induces NF-kappaB activation in resting cells and augments CD40-induced NF-kappaB activation, but has no effect on control STAT1 reporter activity, either at baseline or after IFN-gamma induction. The finding that TRAF-3 binds p62, suggests that TRAF-3 may serve as an adapter molecule at the nuclear membrane, in addition to its known adapter function at the plasma membrane.
Gamper
C
C
Laboratory of Molecular Immunology, Columbia University, New York, NY 10032, USA.
van Eyndhoven
W G
WG
Schweiger
E
E
Mossbacher
M
M
Koo
B
B
Lederman
S
S
D019013:CD40 Antigens / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D016328:NF-kappa B / Q000502:physiology; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins / Q000378:metabolism*; D011506:Proteins / Q000502:physiology*; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D048008:TNF Receptor-Associated Factor 3; D015534:Trans-Activators / Q000502:physiology; D028961:beta Karyopherins
D019013:CD40 Antigens; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D011506:Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D048008:TNF Receptor-Associated Factor 3; D015534:Trans-Activators; D028961:beta Karyopherins; C049312:nuclear pore protein p62