Identification of a human NF-kappaB-activating protein, TAB3.
The NF-kappaB pathway plays a critical role in regulating cellular processes such as immune responses, stress responses, apoptosis, proliferation and differentiation, whereas dysfunction of this pathway has been associated with numerous cancer and immune disorders. We have applied our Random Activation of Gene Expression technology to an NF-kappaB reporter cell line to facilitate the discovery of positive regulators of NF-kappaB activation. A small protein expression library, corresponding to approximately 0.1x genome coverage, was generated and screened for clones exhibiting constitutive activation of NF-kappaB. After isolation of cellular clones displaying the relevant phenotypes, we identified two known components of the NF-kappaB pathway and a hypothetical gene that we have designated the human ortholog of Xenopus TAK1-binding protein 3 (TAB3). Overexpression of human TAB3 was found to activate both NF-kappaB and AP-1 transcription factors. Furthermore, the activation of NF-kappaB by TAB3 was blocked by the NF-kappaB inhibitor, SN50, and by expression of dominant-negative forms of tumor necrosis factor alpha-associated factor 6 and transforming growth factor beta-activated kinase. Taken together, these data demonstrate that TAB3 transforming growth factor is a constituent of the NF-kappaB pathway functioning upstream of tumor necrosis factor alpha-associated factor 6/transforming growth factor beta-activated kinase. Interestingly, increased expression of TAB3 was found in some cancer tissues, and its overexpression in NIH 3T3 cells resulted in cellular transformation, thus establishing a causative link between elevated TAB3 expression, constitutive NF-kappaB activation, and oncogenesis.
Jin
Ge
G
Athersys, Inc., 3201 Carnegie Avenue, Cleveland, OH 44115, USA.
Klika
Alison
A
Callahan
Michelle
M
Faga
Ben
B
Danzig
Joel
J
Jiang
Zhengfan
Z
Li
Xiaoxia
X
Stark
George R
GR
Harrington
John
J
Sherf
Bruce
B
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D019295:Computational Biology; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D016209:Interleukin-8 / Q000032:analysis / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism; D041681:NIH 3T3 Cells; D010455:Peptides / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011506:Proteins / Q000378:metabolism; D048029:TNF Receptor-Associated Factor 6; D019076:Transgenes / Q000235:genetics; D000099151:MAP Kinase Kinase Kinase 7
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D016209:Interleukin-8; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D016328:NF-kappa B; D010455:Peptides; D011506:Proteins; D048029:TNF Receptor-Associated Factor 6; D000099151:MAP Kinase Kinase Kinase 7; C118258:SN50 peptide; C410585:TAB2 protein, human; C481053:TAB3 protein, human; C498761:Tab2 protein, mouse