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Potentiation of the P2X3 ATP receptor by PAR-2 in rat dorsal root ganglia neurons, through protein kinase-dependent mechanisms, contributes to inflammatory pain

Authors

  • Shenglan Wang,

    1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100088, China
    2. Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe, Hyogo 650-8530, Japan
    3. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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  • Yi Dai,

    1. Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe, Hyogo 650-8530, Japan
    2. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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  • Kimiko Kobayashi,

    1. Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe, Hyogo 650-8530, Japan
    2. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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  • Wanjun Zhu,

    1. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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  • Yoko Kogure,

    1. Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe, Hyogo 650-8530, Japan
    2. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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  • Hiroki Yamanaka,

    1. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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  • You Wan,

    1. School of Basic Medical Sciences, Neuroscience Research Institute, Peking University, Beijing 100083, China
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  • Wensheng Zhang,

    1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100088, China
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  • Koichi Noguchi

    1. Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
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Dr Yi Dai, 2Department of Pharmacy, as above.
E-mail: ydai@huhs.ac.jp

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.

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