A key role for redox signaling in rapid P2X7 receptor-induced IL-1 beta processing in human monocytes.
P2X(7) receptors (P2X(7)Rs) are ATP-gated ion channels that trigger caspase-1 activation in the presence of TLR ligands. Inflammatory caspase-1 is responsible for the proteolytic activation of IL-1beta. However, the signaling events that couple P2X(7)Rs to caspase-1 activation remain undefined. In this study we demonstrate that ATP-induced cellular oxidation is critical for caspase-1 activation and subsequent IL-1beta processing. Purinergic receptor stimulation, including P2X(7)Rs, of endotoxin-primed human monocytes augments NADPH oxidase activity whereas concurrent purinergic receptor stimulation triggers protein denitroyslation, leading to the formation of peroxynitrite. IL-1beta cleavage is blocked under conditions where superoxide anion formation is blocked or monocytes are treated with antioxidants or a peroxynitrite scavenger. Nigericin, a K(+)/H(+) antiporter, also increases NADPH oxidase activity, leading to IL-1beta and caspase-1 processing that is blocked by a peroxynitrite scavenger or inhibition of NADPH oxidase. These data demonstrate that signaling via NADPH oxidase activity is fundamental for the processing of mature IL-1beta induced by P2X(7)R stimulation.
Department of Pharmacy and Pharmacology, University of Bath, Bath, UK.
James
J
Hewinson
Samantha F
SF
Moore
Christian
C
Glover
Andrew G
AG
Watts
Amanda B
AB
MacKenzie
D000255:Adenosine Triphosphate / Q000502:physiology; D020170:Caspase 1 / Q000737:chemistry / Q000378:metabolism; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000276:immunology; D045604:Extracellular Fluid / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D006801:Humans; D053583:Interleukin-1beta / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D015640:Ion Channel Gating / Q000276:immunology; D009000:Monocytes / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D016877:Oxidants / Q000502:physiology; D010084:Oxidation-Reduction; D011499:Protein Processing, Post-Translational / Q000276:immunology*; D018048:Receptors, Purinergic P2 / Q000737:chemistry* / Q000502:physiology*; D058486:Receptors, Purinergic P2X7; D026403:S-Nitrosothiols / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*
D053583:Interleukin-1beta; D016877:Oxidants; C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D026403:S-Nitrosothiols; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D019255:NADPH Oxidases; D020170:Caspase 1