抄録
We have previously showed desensitization of TRPV1 activity by successive applications of 100 nM capsaicin and its reversal by protein kinase C (PKC) in DRG neurons and CHO cells using Ca2+-imaging. We have performed whole-cell patch-clamp recordings in HEK293 cells and Ca2+-imagings in HEK293 and HeLa cells to clarify the more detailed mechanism. Capsaicin-activated currents were desensitized upon repetitive capsaicin application and re-sensitized upon activation of PKC by PMA in HEK293 cells expressing wild type TRPV1 but not S502A/S800A mutant insensitive to PKC. Furthermore, the re-sensitization was inhibited by PKCε translocation inhibitor. PKCε expression was significantly higher in HEK293 cells or CHO cells than in HeLa cells where re-sensitization was not observed using Ca2+-imaging method. The re-sensitization was restored by induction of PKCε into HeLa cells. The re-sensitization was accompanied by the increase in phosphorylated TRPV1 detected using anti-phospho-TRPV1 antibody made against phosphorylated S800. These results suggest that PMA-induced re-sensitization of TRPV1 activity occurs through PKCε-mediated phosphorylation of TRPV1 at S800. [Jpn J Physiol 55 Suppl:S159 (2005)]
