| 18682396 |
Schwarzer C, Fu Z, Fischer H, Machen TE: Redox-independent activation of NF-kappaB by Pseudomonas aeruginosa pyocyanin in a cystic fibrosis airway epithelial cell line. J Biol Chem. 2008 Oct 3;283(40):27144-53. Epub 2008 Aug 5.
The roles of the Pseudomonas aeruginosa-derived pigment pyocyanin (PYO) as an oxidant and activator of the proinflammatory transcription factor NF-kappaB were tested in a cystic fibrosis (CF) airway epithelial cell line, CF15. 100 microm PYO on its own had no effect or only small effects to activate NF-kappaB (<1.5-fold), but PYO synergized with the TLR5 agonist flagellin. Flagellin activated NF-kappaB 4-20-fold, and PYO increased these activations > 2.5-fold. PYO could have synergized with flagellin to activate NF-kappaB by redox cycling with NADPH, generating superoxide (O (2)*), hydrogen peroxide (H (2) O (2)), and hydroxyl radical (HO*). Cytosol-targeted, redox-sensitive roGFP1 and imaging microscopy showed that 1-100 microm PYO oxidized CF15 cytosol redox potential (Psi (cyto)) from -325 mV (control) to -285 mV. O (2)* (derived from KO (2)*. or xanthine + xanthine oxidase) or H (2) O (2) oxidized Psi (cyto) dose-dependently but did not activate NF-kappaB, even in the presence of flagellin, and 400 microm H (2) O (2) inhibited NF-kappaB. Overexpressing intracellular catalase decreased effects of PYO and H (2) O (2) on Psi (cyto) but did not affect flagellin + PYO-activated NF-kappaB. Catalase also reversed the inhibitory effects of H (2) O (2) on NF-kappaB. The HO* scavenger DMSO did not alter the effects of PYO on Psi (cyto) and NF-kappaB. The synergistic NF-kappaB activation was calcium-independent. Thus, in the presence of flagellin, PYO activated NF-kappaB through a redox- and calcium-independent effect. |
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