Polyunsaturated fatty acids modulate NOX 4 anion superoxide production in human fibroblasts
Résumé
The strong reactive oxygen species (ROS) production, part of an antioxidant response of human fibroblasts triggered by docosahexaenoic acid, served as a model for deciphering the relative contribution of NADPH oxidase (NOX) to ROS production, as the role of this enzymatic system remains controversial. Using hydroxyethidium fluorescence for fibroblast ROS production, RT-PCR for NOX 4 mRNA quantification, and mRNA silencing, we show that ROS production evolves in parallel with the catalytic activity of NOX and is suppressed by siNOX 4 silencing. Apocynin and plumbagin, specific inhibitors of NOX, prevent ROS production in this cellular model and confirm the role of NOX 4 for this production. Furthermore we show that, in cell lysates, NOX 4 activity can be modulated by polyunsaturated fatty acids (PUFAs) at the micro molar level in the presence of calcium: NOX 4 activity is increased by arachidonic acid (around 175% of control), and conjugated linoleic acid is a potent inhibitor (50% of control). Unexpectedly, intracellular superoxide dismutase (SOD) does not participate in the modulation of this ROS production and the opposite effects of some PUFA, described in our experiments, could suggest another way of regulating NOX activity.
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