Characterization of COMMD protein-protein interactions in NF-kappaB signalling.
COMMD [copper metabolism gene MURR1 (mouse U2af1-rs1 region 1) domain] proteins constitute a recently identified family of NF-kappaB (nuclear factor kappaB)-inhibiting proteins, characterized by the presence of the COMM domain. In the present paper, we report detailed investigation of the role of this protein family, and specifically the role of the COMM domain, in NF-kappaB signalling through characterization of protein-protein interactions involving COMMD proteins. The small ubiquitously expressed COMMD6 consists primarily of the COMM domain. Therefore COMMD1 and COMMD6 were analysed further as prototype members of the COMMD protein family. Using specific antisera, interaction between endogenous COMMD1 and COMMD6 is described. This interaction was verified by independent techniques, appeared to be direct and could be detected throughout the whole cell, including the nucleus. Both proteins inhibit TNF (tumour necrosis factor)-induced NF-kappaB activation in a non-synergistic manner. Mutation of the amino acid residues Trp24 and Pro41 in the COMM domain of COMMD6 completely abolished the inhibitory effect of COMMD6 on TNF-induced NF-kappaB activation, but this was not accompanied by loss of interaction with COMMD1, COMMD6 or the NF-kappaB subunit RelA. In contrast with COMMD1, COMMD6 does not bind to IkappaBalpha (inhibitory kappaBalpha), indicating that both proteins inhibit NF-kappaB in an overlapping, but not completely similar, manner. Taken together, these data support the significance of COMMD protein-protein interactions and provide new mechanistic insight into the function of this protein family in NF-kappaB signalling.
Laboratory of Metabolic and Endocrine Diseases, University Medical Center, Utrecht, 3584 EA, The Netherlands.
Prim
P
de Bie
Bart
B
van de Sluis
Ezra
E
Burstein
Karen J
KJ
Duran
Ruud
R
Berger
Colin S
CS
Duckett
Cisca
C
Wijmenga
Leo W J
LW
Klomp
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins; D002478:Cells, Cultured; D017124:Conserved Sequence / Q000235:genetics; D004285:Dogs; D005091:Exons / Q000235:genetics; D005453:Fluorescence; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; C480519:COMMD1 protein, human; C512572:COMMD6 protein, human; D002352:Carrier Proteins; D020672:I-kappa B Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D011506:Proteins; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha