Premium
Protease‐activated receptor 2 sensitizes TRPV1 by protein kinase Cɛ‐ and A‐dependent mechanisms in rats and mice
Author(s) -
Amadesi Silvia,
Cottrell Graeme S.,
Divino Lorna,
Chapman Kevin,
Grady Eileen F.,
Bautista Francisco,
Karanjia Rustum,
BarajasLopez Carlos,
Vanner Stephen,
Vergnolle Nathalie,
Bunnett Nigel W.
Publication year - 2006
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2006.111534
Subject(s) - trpv1 , chemistry , microbiology and biotechnology , transient receptor potential channel , hek 293 cells , protein kinase c , hyperalgesia , protease activated receptor 2 , receptor , agonist , phospholipase c , kinase , biochemistry , nociception , biology , enzyme linked receptor
Proteases that are released during inflammation and injury cleave protease‐activated receptor 2 (PAR 2 ) on primary afferent neurons to cause neurogenic inflammation and hyperalgesia. PAR 2 ‐induced thermal hyperalgesia depends on sensitization of transient receptor potential vanilloid receptor 1 (TRPV1), which is gated by capsaicin, protons and noxious heat. However, the signalling mechanisms by which PAR 2 sensitizes TRPV1 are not fully characterized. Using immunofluorescence and confocal microscopy, we observed that PAR 2 was colocalized with protein kinase (PK) Cɛ and PKA in a subset of dorsal root ganglia neurons in rats, and that PAR 2 agonists promoted translocation of PKCɛ and PKA catalytic subunits from the cytosol to the plasma membrane of cultured neurons and HEK 293 cells. Subcellular fractionation and Western blotting confirmed this redistribution of kinases, which is indicative of activation. Although PAR 2 couples to phospholipase Cβ, leading to stimulation of PKC, we also observed that PAR 2 agonists increased cAMP generation in neurons and HEK 293 cells, which would activate PKA. PAR 2 agonists enhanced capsaicin‐stimulated increases in [Ca 2+ ] i and whole‐cell currents in HEK 293 cells, indicating TRPV1 sensitization. The combined intraplantar injection of non‐algesic doses of PAR 2 agonist and capsaicin decreased the latency of paw withdrawal to radiant heat in mice, indicative of thermal hyperalgesia. Antagonists of PKCɛ and PKA prevented sensitization of TRPV1 Ca 2+ signals and currents in HEK 293 cells, and suppressed thermal hyperalgesia in mice. Thus, PAR 2 activates PKCɛ and PKA in sensory neurons, and thereby sensitizes TRPV1 to cause thermal hyperalgesia. These mechanisms may underlie inflammatory pain, where multiple proteases are generated and released.