scholarly journals Transcriptional regulation of the rat type IIA phospholipase A2 gene by cAMP and interleukin-1β in vascular smooth muscle cells: interplay of the CCAAT/enhancer binding protein (C/EBP), nuclear factor-κB and Ets transcription factors

2002 ◽  
Vol 368 (2) ◽  
pp. 415-424 ◽  
Author(s):  
Valérie ANTONIO ◽  
Arthur BROUILLET ◽  
Brigitte JANVIER ◽  
Claire MONNE ◽  
Gilbert BEREZIAT ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Phospholipase A2 ◽  
Protein C ◽  
Muscle Cells ◽  
Nuclear Factor Κb ◽  
Interleukin 1Β ◽  
Nuclear Factor ◽  
Enhancer Binding Protein ◽  
Responsive Element

The abundant secretion of type IIA secreted phospholipase A2 (sPLA2) is a major feature of the inflammatory process of atherosclerosis. sPLA2 is crucial for the development of inflammation, as it catalyses the production of lipid mediators and induces the proliferation of smooth muscle cells. We have analysed the activation of sPLA2 transcription by cAMP and interleukin-1β (IL-1β), and shown that the 500bp region upstream of the transcription start site of the rat sPLA2 gene is implicated in activation by synergistically acting cAMP and IL-1β. We transiently transfected and stimulated rat smooth muscle cells in primary culture and measured the promoter activities of serial and site-directed deletion mutants of sPLA2—luciferase constructs. A distal region, between −488 and −157 bp, bearing a CAAT/enhancer binding protein (C/EBP)-responsive element (-242 to −223) was sufficient for cAMP/protein kinase A-mediated sPLA2 promoter activation. We find evidence for the first time that activation of the sPLA2 promoter by IL-1β requires activation of an Ets-responsive element in the −184 to −180 region of the distal promoter via the Ras pathway and a nuclear factor-κB site at positions −141 to −131 of the proximal promoter. We also used electrophoretic mobility shift assays to identify five binding sites for the Sp1 factor; a specific inhibitor of Sp1, mithramycin A, showed that this factor is crucial for the basal activity of the sPLA2 promoter.

Selected Contribution: Synergism between TNF-α and IL-1β in airway smooth muscle cells: implications for β-adrenergic responsiveness

2001 ◽  
Vol 91 (3) ◽  
pp. 1467-1474 ◽  
Author(s):  
Paul E. Moore ◽  
Thomas Lahiri ◽  
Johanne D. Laporte ◽  
Trudi Church ◽  
Reynold A. Panettieri ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Muscle Cells ◽  
Nuclear Factor Κb ◽  
Airway Smooth Muscle Cells ◽  
Nuclear Factor ◽  
Tnf Α ◽  
Combined Administration ◽  
Cox 2

In human cultured airway smooth muscle cells, interleukin (IL)-1β increases cyclooxygenase (COX)-2 expression and PGE2 release, ultimately resulting in decreased β-adrenergic responsiveness. In this study, we aimed to determine whether tumor necrosis factor-α (TNF-α) synergizes with IL-1β in the induction of these events. TNF-α alone, at concentrations up to 10 ng/ml, had no effect on COX-2 protein expression; at concentrations as low as 0.1 ng/ml, it significantly enhanced the ability of IL-1β (0.2 ng/ml) to induce COX-2 and to increase PGE2 release. IL-1β and TNF-α in combination also significantly enhanced COX-2 promoter activity, indicating that synergism between the cytokines is mediated at the level of gene transcription. Although IL-1β and TNF-α each increased nuclear factor-κB activation and induced extracellular regulated kinase and p38 phosphorylation, combined administration of the cytokines did not enhance either nuclear factor-κB or mitogen-activated protein kinase activation. Combined administration of IL-1β (0.2 ng/ml) and TNF-α (0.1 or 1.0 ng/ml) reduced the ability of isoproterenol to decrease human airway smooth muscle cell stiffness, as measured by magnetic twisting cytometry, even though individually these cytokines, at these concentrations, had no effect on isoproterenol responses. Treatment with the selective COX-2 inhibitor NS-398 abolished the synergistic effects of TNF-α and IL-1β on β-adrenergic responsiveness. Our results indicate that low concentrations of IL-1β and TNF-α synergize to promote β-adrenergic hyporesponsiveness and that effects on COX-2 expression and PGE2 are responsible for these events. The data suggest that the simultaneous release in the airway, of even very small amounts of cytokines, can have important functional consequences.

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