Homeostatic interactions between MEKK3 and TAK1 involved in NF-kappaB signaling.
Several members of the mitogen-activated protein kinase kinase kinase (MAP3K) family including MEKK3 and TGFbeta-activating kinase (TAK1) play nonredundant roles in activation of the NF-kappaB transcription factor. However, the mechanism by which MEKK3 mediates NF-kappaB signaling is not fully understood. In this report we investigate the association of murine MEKK3 with other proteins and their roles in NF-kappaB activation. Using tandem affinity purification TAK1 was identified as an endogenous protein that interacts with MEKK3. MEKK3-TAK1 interactions were confirmed by fluorescence resonance energy transfer and coimmunoprecipitation. MEKK3-TAK1 complexes contain non-phosphorylated forms of both molecules. Expression of non-phosphorylated TAK1 interferes with MEKK3 phosphorylation and NF-kappaB reporter activity induced by transient MEKK3 expression or TNFalpha stimulation. Addition of TAB1 facilitates TAK1 autophosphorylation and reverses the inhibitory effects of TAK1 on MEKK3 phosphorylation and NF-kappaB signal transduction in human 293 cells and TAK1 deficient mouse embryonic fibroblasts. The data provide insights into the homeostatic interactions that maintain basal NF-kappaB levels by holding the enzymes MEKK3 and TAK1 in their inactive state.
Di
Yuwei
Y
Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.
Li
Shitao
S
Wang
Lingyan
L
Zhang
Ye
Y
Dorf
Martin E
ME
D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006706:Homeostasis; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D048748:MAP Kinase Kinase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D015398:Signal Transduction; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D000099151:MAP Kinase Kinase Kinase 7
D047908:Intracellular Signaling Peptides and Proteins; D048748:MAP Kinase Kinase Kinase 3; D020930:MAP Kinase Kinase Kinases; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D000099151:MAP Kinase Kinase Kinase 7; C099510:TAB1 protein, MAPKKK activator, vertebrate; C482626:Map3k3 protein, mouse