IkappaBalpha degradation and nuclear factor-kappaB DNA binding are insufficient for interleukin-1beta and tumor necrosis factor-alpha-induced kappaB-dependent transcription. Requirement for an additional activation pathway.
Two closely related IkappaBalpha kinases as well as the upstream kinase, NIK, which integrates interleukin-1beta (IL-1beta)- and tumor necrosis factor (TNF)-alpha-dependent activation of the transcription factor NF-kappaB have recently been described. However, in this emerging pathway the role of previously identified components of cytokine-induced NF-kappaB activation, namely phosphatidylcholine-specific phospholipase C and protein kinase C, remains unclear. We now show that, in A549 human alveolar epithelial cells, the activation of a stably transfected NF-kappaB-dependent reporter gene by TNF-alpha and IL-1beta is completely blocked by the phosphatidylcholine-specific phospholipase C inhibitor D609 and the protein kinase C inhibitor RO31-8220. However, IL-1beta-induced IkappaBalpha degradation as well as NF-kappaB nuclear translocation and DNA binding, as determined by Western blot and electro-mobility shift assay, respectively, are not affected by these inhibitors. A similar effect, although less pronounced, is observed with the p38 mitogen-activated protein kinase inhibitor SB 203580. On the basis of these data we propose the existence of a second signaling pathway induced by IL-1beta and TNF-alpha that is activated in parallel to the cascade leading to IkappaBalpha degradation and is specifically required for NF-kappaB-dependent transcriptional competency.
Bergmann
M
M
Department of Thoracic Medicine, National Heart and Lung Institute, Imperial College School of Medicine, Dovehouse Street, London SW3 6LY, United Kingdom.
Hart
L
L
Lindsay
M
M
Barnes
P J
PJ
Newton
R
R
D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D020672:I-kappa B Proteins; D007211:Indoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000502:physiology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D011485:Protein Binding; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D007211:Indoles; D007375:Interleukin-1; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D004247:DNA; D011493:Protein Kinase C; D010738:Type C Phospholipases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; C064758:Ro 31-8220