NIBP, a novel NIK and IKK(beta)-binding protein that enhances NF-(kappa)B activation.
The transcription factor NF-kappaB plays an important role in both physiological and pathological events in the central nervous system. Nevertheless, the mechanisms of NF-kappaB-mediated regulation of gene expression, and the signaling molecules participating in the NF-kappaB pathway in the central nervous system are, to date, poorly understood. To identify such molecules, we conducted a yeast two-hybrid screen of a human brain cDNA library using NIK as bait. As a result, we identified a novel NIK and IKK(beta) binding protein designated NIBP that is mainly expressed in brain, muscle, heart, and kidney. Interestingly, low levels of expression were detected in immune tissues such as spleen, thymus, and peripheral blood leukocytes, where NF-kappaB is known to modulate immune function. We demonstrated by immunohistochemistry that NIBP expression in the brain is localized to neurons. NIBP physically interacts with NIK, IKK(beta), but not IKK(alpha) or IKK(gamma). NIBP overexpression potentiates tumor necrosis factor-alpha-induced NF-kappaB activation through increased phosphorylation of the IKK complex and its downstream I(kappa)B(alpha) and p65 substrates. Finally, knockdown of NIBP expression by small interfering RNA reduces tumor necrosis factor-alpha-induced NF-kappaB activation, prevents nerve growth factor-induced neuronal differentiation, and decreases Bcl-xL gene expression in PC12 cells. Our data demonstrate that NIBP, by interacting with NIK and IKK(beta), is a new enhancer of the cytokine-induced NF-(kappa)B signaling pathway. Because of its neuronal expression, we propose that NIBP may be a potential target for modulating the NF-(kappa)B signaling cascade in neuronal pathologies dependent upon abnormal activation of this pathway.
Hu
Wen-Hui
WH
The Miami Project to Cure Paralysis, Department of Neurological Surgery, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
Pendergast
Julie S
JS
Mo
Xian-Ming
XM
Brambilla
Roberta
R
Bracchi-Ricard
Valerie
V
Li
Fang
F
Walters
Winston M
WM
Blits
Bas
B
He
Li
L
Schaal
Sandra M
SM
Bethea
John R
JR
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism* / Q000502:physiology*; D002454:Cell Differentiation; D003001:Cloning, Molecular; D016207:Cytokines / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D036341:Intercellular Signaling Peptides and Proteins; D016086:Lentivirus / Q000235:genetics; D008969:Molecular Sequence Data; D016716:PC12 Cells; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D014018:Tissue Distribution; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D051020:bcl-X Protein; D000097782:NF-kappaB-Inducing Kinase
D002352:Carrier Proteins; D016207:Cytokines; D018076:DNA, Complementary; D005982:Glutathione Transferase; D051550:I-kappa B Kinase; D036341:Intercellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; D000097782:NF-kappaB-Inducing Kinase; C494811:BCL2L1 protein, human; C494813:Bcl2l1 protein, rat; C503887:TRAPPC9 protein, human; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human