title: Potentiation of the P2X3 ATP receptor by PAR-2 in rat dorsal root ganglia neurons, through protein kinase-dependent mechanisms, contributes to inflammatory pain.
abstract: Proinflammatory agents trypsin and mast cell tryptase cleave and activate protease-activated receptor-2 (PAR-2), which is expressed on sensory nerves and causes neurogenic inflammation. P2X3 is a subtype of the ionotropic receptors for adenosine 5'-triphosphate (ATP), and is mainly localized on nociceptors. Here, we show that a functional interaction of the PAR-2 and P2X3 in primary sensory neurons could contribute to inflammatory pain. PAR-2 activation increased the P2X3 currents evoked by α, β, methylene ATP in dorsal root ganglia (DRG) neurons. Application of inhibitors of either protein kinase C (PKC) or protein kinase A (PKA) suppressed this potentiation. Consistent with this, a PKC or PKA activator mimicked the PAR-2-mediated potentiation of P2X3 currents. In the in vitro phosphorylation experiments, application of a PAR-2 agonist failed to establish phosphorylation of the P2X3 either on the serine or the threonine site. In contrast, application of a PAR-2 agonist induced trafficking of the P2X3 from the cytoplasm to the plasma membrane. These findings indicate that PAR-2 agonists may potentiate the P2X3, and the mechanism of this potentiation is likely to be a result of translocation, but not phosphorylation. The functional interaction between P2X3 and PAR-2 was also confirmed by detection of the α, β, methylene-ATP-evoked extracellular signal-regulated kinases (ERK) activation, a marker of neuronal signal transduction in DRG neurons, and pain behavior. These results demonstrate a functional interaction of the protease signal with the ATP signal, and a novel mechanism through which protease released in response to tissue inflammation might trigger the sensation to pain through P2X3 activation.
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100088, China.
authors.forename: Shenglan
authors.initials: S
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Dai
authors.forename: Kimiko
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Wanjun
authors.initials: W
authors.lastname: Zhu
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kogure
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamanaka
authors.forename: You
authors.initials: Y
authors.lastname: Wan
authors.forename: Wensheng
authors.initials: W
authors.lastname: Zhang
authors.forename: Koichi
authors.initials: K
authors.lastname: Noguchi
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000378:metabolism* / Q000502:physiology; D007211:Indoles / Q000494:pharmacology; D007249:Inflammation / Q000150:complications; D020935:MAP Kinase Signaling System; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D008564:Membrane Potentials; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D010146:Pain / Q000209:etiology / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021381:Protein Transport; D058911:Purinergic P2X Receptor Agonists / Q000494:pharmacology; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D044464:Receptor, PAR-2 / Q000819:agonists / Q000378:metabolism*; D058477:Receptors, Purinergic P2X3 / Q000187:drug effects / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D002227:Carbazoles; D007211:Indoles; D008301:Maleimides; D058911:Purinergic P2X Receptor Agonists; D058920:Purinergic P2X Receptor Antagonists; D011758:Pyrroles; D044464:Receptor, PAR-2; D058477:Receptors, Purinergic P2X3; D005576:Colforsin; C016658:phorbolol myristate acetate; C057416:KT 5720; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate