Ras and mitogen-activated protein kinase kinase kinase-1 coregulate activator protein-1- and nuclear factor-kappaB-mediated gene expression in airway epithelial cells.
In 16HBE14o- human bronchial epithelial cells, maximal tumor necrosis factor (TNF)-alpha-induced interleukin (IL)-8 expression depends on the activation of two distinct signaling pathways, one constituted in part by activator protein (AP)-1 and the other by nuclear factor (NF)-kappaB. We examined the upstream signaling intermediates responsible for IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in this system, hypothesizing that p21 Ras and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase (MEKK)-1 function as common upstream activators of both the AP-1 and NF-kappaB pathways. TNF-alpha treatment induced both Ras and MEKK1 activation. Dominant-negative forms of Ras (N17Ras) and MEKK1 (MEKK1-KM) each inhibited TNF-alpha-induced transcription from IL-8 and GM-CSF promoters. Ras was required for maximal activation of extracellular signal-regulated kinase (ERK) and Jun amino terminal kinase (JNK) as well as AP-1 and NF-kappaB transcriptional activities, but not for activation of IkappaB kinase (IKK)-beta, an upstream activator of NF-kappaB. MEKK1 was required for maximal activation of ERK, JNK, and IKK, as well as for maximal AP-1 and NF-kappaB transcriptional activities. We conclude that Ras regulates TNF-alpha-induced chemokine expression by activating the AP-1 pathway and enhancing transcriptional function of NF-kappaB, whereas MEKK1 activates both the AP-1 and NF-kappaB pathways.
Zhou
Limei
L
Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109-0212, USA.
Tan
Alan
A
Iasvovskaia
Svetlana
S
Li
Jing
J
Lin
Anning
A
Hershenson
Marc B
MB
D001980:Bronchi / Q000166:cytology; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics; D048031:JNK Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
D016209:Interleukin-8; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D018631:ras Proteins