15-Epi-lipoxin A4 inhibits human neutrophil superoxide anion generation by regulating polyisoprenyl diphosphate phosphatase 1.
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ABSTRACT: Regulation of leukocyte activation is critical to limit unintended tissue injury during acute inflammation. On neutrophil activation, polyisoprenyl diphosphate phosphatase 1 (PDP1) rapidly converts presqualene diphosphate to presqualene monophosphate to facilitate cell activation. Lipoxins are potent anti-inflammatory mediators for neutrophils, yet their counterregulatory signaling mechanisms remain to be determined. 15-Epi-lipoxin A4 (15-epi-LXA4) blocked agonist-initiated association of the nicotinamide adenine dinucleotide phosphate oxidase components p47(PHOX) and p22(PHOX) in human neutrophils. 15-Epi-LXA4 (0.1-100 nM) inhibited neutrophil superoxide anion (O2(-)) generation in a concentration- and ALX/FPR2 receptor-dependent manner that was disrupted by PDP1-specific antibodies. In differentiated HL60 cells, a myeloid cell line, agonist-initiated O2(-) generation was inhibited by PDP1 siRNA. Recombinant human PDP1 was directly phosphorylated in vitro by select protein kinase C (PKC) isoforms, including PKC?II. When neutrophils were exposed to formyl-methionyl-leucyl-phenylalanine (fMLP), PKC?II was rapidly phosphorylated and physically associated with PDP1. Agonist-initiated conversion of neutrophil presqualene diphosphate to presqualene monophosphate was blocked by PKC?II inhibition. Neutrophil exposure to 15-epi-LXA4 attenuated fMLP triggered PKC?II phosphorylation and its interactions with PDP1. Together, these findings indicate that PDP1 serves an integral signaling role in neutrophil proinflammatory responses and as a target for counter-regulatory mediators.
SUBMITTER: Carlo T
PROVIDER: S-EPMC3688747 | biostudies-literature | 2013 Jul
REPOSITORIES: biostudies-literature
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