Identification of NAP1, a regulatory subunit of IkappaB kinase-related kinases that potentiates NF-kappaB signaling.
The IkappaB kinase (IKK)-related kinase NAK (also known as TBK or T2K) contributes to the activation of NF-kappaB-dependent gene expression. Here we identify NAP1 (for NAK-associated protein 1), a protein that interacts with NAK and its relative IKK epsilon (also known as IKKi). NAP1 activates NAK and facilitates its oligomerization. Interestingly, the NAK-NAP1 complex itself effectively phosphorylated serine 536 of the p65/RelA subunit of NF-kappaB, and this activity was stimulated by tumor necrosis factor alpha (TNF-alpha). Overexpression of NAP1 specifically enhanced cytokine induction of an NF-kappaB-dependent, but not an AP-1-dependent, reporter. Depletion of NAP1 reduced NF-kappaB-dependent reporter gene expression and sensitized cells to TNF-alpha-induced apoptosis. These results define NAP1 as an activator of IKK-related kinases and suggest that the NAK-NAP1 complex may protect cells from TNF-alpha-induced apoptosis by promoting NF-kappaB activation.
Fujita
Fumitaka
F
Department of Biochemistry and Cell Biology, Graduate School of Medicine, Nagoya City University, Mizuho-ku, Nagoya 467-8601, Japan.
Taniguchi
Yuko
Y
Kato
Takashi
T
Narita
Yasuko
Y
Furuya
Akiko
A
Ogawa
Tatsuhiro
T
Sakurai
Hiroaki
H
Joh
Takashi
T
Itoh
Makoto
M
Delhase
Mireille
M
Karin
Michael
M
Nakanishi
Makoto
M
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D004789:Enzyme Activation; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*; D014018:Tissue Distribution; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020798:Two-Hybrid System Techniques
C582344:AZI2 protein, mouse; D048868:Adaptor Proteins, Signal Transducing; D016328:NF-kappa B; D021122:Protein Subunits; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; C498588:Tbk1 protein, mouse; D017346:Protein Serine-Threonine Kinases; C403191:TBK1 protein, human; C496559:CHUK protein, human; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse