Protein kinase C activation potentiates gating of the vanilloid receptor VR1 by capsaicin, protons, heat and anandamide

Protein kinase C activation potentiates gating of the vanilloid receptor VR1 by capsaicin,... 1 The effects of activation of protein kinase C (PKC) on membrane currents gated by capsaicin, protons, heat and anandamide were investigated in primary sensory neurones from neonatal rat dorsal root ganglia (DRG) and in HEK293 cells (human embryonic kidney cell line) transiently or stably expressing the human vanilloid receptor hVR1. 2 Maximal activation of PKC by a brief application of phorbol 12‐myristate 13‐acetate (PMA) increased the mean membrane current activated by a low concentration of capsaicin by 1.65‐fold in DRG neurones and 2.18‐fold in stably transfected HEK293 cells. Bradykinin, which activates PKC, also enhanced the response to capsaicin in DRG neurones. The specific PKC inhibitor RO31‐8220 prevented the enhancement caused by PMA. 3 Activation of PKC did not enhance the membrane current at high concentrations of capsaicin, showing that PKC activation increases the probability of channel opening rather than unmasking channels. 4 Application of PMA alone activated an inward current in HEK293 cells transiently transfected with VR1. The current was suppressed by the VR1 antagonist capsazepine. PMA did not, however, activate a current in the large majority of DRG neurones nor in HEK293 cells stably transfected with VR1. 5 Removing external Ca2+ enhanced the response to a low concentration of capsaicin 2.40‐fold in DRG neurones and 3.42‐fold in HEK293 cells. Activation of PKC in zero Ca2+ produced no further enhancement of the response to capsaicin in either DRG neurones or HEK293 cells stably transfected with VR1. 6 The effects of PKC activation on the membrane current gated by heat, anandamide and low pH were qualitatively similar to those on the capsaicin‐gated current. 7 The absence of a current activated by PMA in most DRG neurones or in stably transfected HEK293 cells suggests that activation of PKC does not directly open VR1 channels, but instead increases the probability that they will be activated by capsaicin, heat, low pH or anandamide. Removal of calcium also potentiates activation, and PKC activation then has no further effect. The results are consistent with a model in which phosphorylation of VR1 by PKC increases the probability of channel gating by agonists, and in which dephosphorylation occurs by a calcium‐dependent process. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Physiology Wiley

Protein kinase C activation potentiates gating of the vanilloid receptor VR1 by capsaicin, protons, heat and anandamide

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Publisher
Wiley
Copyright
Copyright © 2001 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0022-3751
eISSN
1469-7793
DOI
10.1111/j.1469-7793.2001.00813.x
Publisher site
See Article on Publisher Site

Abstract

1 The effects of activation of protein kinase C (PKC) on membrane currents gated by capsaicin, protons, heat and anandamide were investigated in primary sensory neurones from neonatal rat dorsal root ganglia (DRG) and in HEK293 cells (human embryonic kidney cell line) transiently or stably expressing the human vanilloid receptor hVR1. 2 Maximal activation of PKC by a brief application of phorbol 12‐myristate 13‐acetate (PMA) increased the mean membrane current activated by a low concentration of capsaicin by 1.65‐fold in DRG neurones and 2.18‐fold in stably transfected HEK293 cells. Bradykinin, which activates PKC, also enhanced the response to capsaicin in DRG neurones. The specific PKC inhibitor RO31‐8220 prevented the enhancement caused by PMA. 3 Activation of PKC did not enhance the membrane current at high concentrations of capsaicin, showing that PKC activation increases the probability of channel opening rather than unmasking channels. 4 Application of PMA alone activated an inward current in HEK293 cells transiently transfected with VR1. The current was suppressed by the VR1 antagonist capsazepine. PMA did not, however, activate a current in the large majority of DRG neurones nor in HEK293 cells stably transfected with VR1. 5 Removing external Ca2+ enhanced the response to a low concentration of capsaicin 2.40‐fold in DRG neurones and 3.42‐fold in HEK293 cells. Activation of PKC in zero Ca2+ produced no further enhancement of the response to capsaicin in either DRG neurones or HEK293 cells stably transfected with VR1. 6 The effects of PKC activation on the membrane current gated by heat, anandamide and low pH were qualitatively similar to those on the capsaicin‐gated current. 7 The absence of a current activated by PMA in most DRG neurones or in stably transfected HEK293 cells suggests that activation of PKC does not directly open VR1 channels, but instead increases the probability that they will be activated by capsaicin, heat, low pH or anandamide. Removal of calcium also potentiates activation, and PKC activation then has no further effect. The results are consistent with a model in which phosphorylation of VR1 by PKC increases the probability of channel gating by agonists, and in which dephosphorylation occurs by a calcium‐dependent process.

Journal

The Journal of PhysiologyWiley

Published: Aug 1, 2001

References

  • Neurogenic hyperalgesia: The search for the primary cutaneous afferent fibers that contribute to capsaicin‐induced pain and hyperalgesia
    Baumann, Baumann; Simone, Simone; Shain, Shain; LaMotte, LaMotte
  • Responses of cat corneal sensory receptors to mechanical and thermal stimulation
    Belmonte, Belmonte; Giraldez, Giraldez
  • Pain, hyperalgesia and activity in nociceptive C units in humans after intradermal injection of capsaicin
    LaMotte, LaMotte; Lundberg, Lundberg; Torebjork, Torebjork
  • Albumin stimulates uptake of calcium into subcellular stores in rat cortical astrocytes
    Nadal, Nadal; Fuentes, Fuentes; McNaughton, McNaughton
  • The endogenous lipid anandamide is a full agonist at the human vanilloid receptor (hVR1)
    Smart, Smart; Gunthorpe, Gunthorpe; Jerman, Jerman; Nasir, Nasir; Gray, Gray; Muir, Muir; Chambers, Chambers; Randall, Randall; Davis, Davis
  • The protein kinase C family for neuronal signaling
    Tanaka, Tanaka; Nishizuka, Nishizuka

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