Camphor modulates TRPV3 cation channels activity by interacting with critical pore-region cysteine residues

Pak J Pharm Sci. 2013 May;26(3):431-8.

Abstract

TRPV3 ion channels mediate thermo-transduction, nociception, inflammation and dermatitis in mammals. TRPV1-4 proteins have been shown to have conserved cysteine-residues in the pore-forming regions. These residues participate in channel activation via S-nitrosylation of channel proteins. Camphor is a commonly used ligand for TRPV3 channels. Thus the knowledge about the potential binding/interacting site(s) for camphor will help to design effective and potent analgesic compounds. In an overlap-extension PCR method, following primer-pairs were used to mutate conserved cysteine-residues in the pore-region of TRPV3 channels; GATTGAGAATcCTCCAAGGACAAAAAGGAC, TRPV3-C612S-Fw and GTCCTTGGAGgACTTCTCAATCAGTCAGTGAGG, TRPV3-C612S-Rv primers pair. And for TRPV3-C619S: GGACTCcAGTTCCTATGGCCAGC, TRPV3-C619S-Fw and GCTGGCCATAgGAACTGGAGTCC, TRPV3-C619S-Rv respectively. All cDNA constructs were confirmed by DNA-sequencing and used to make cRNAs. Oocytes expressing mTRPV3-C619S and mTRPV3-C612S mutant channels were challenged with 2-APB (1 mM), camphor (10 mM) and dihydrocarveol (10 mM) either at -40 mV or +40 mV holding potentials in voltage-clamp experiments. Responses of both mutants to 2-APB were similar to wild-type mTRPV3. Interestingly, responses to camphor were totally lost in mTRPV3-C619S mutant, while responses to dihydrocarveol remained intact. In contrast mTRPV3-C612S displayed slightly altered (16±2 % reduction) phenotype with respect to camphor sensitivity. It is concluded that pore-region cysteines play critical role in camphor sensitivity of TRPV3 ion channels.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Boron Compounds / pharmacology
  • Calcium / metabolism
  • Camphor / pharmacology*
  • Cysteine / metabolism*
  • DNA, Complementary / genetics
  • Mice
  • Molecular Sequence Data
  • Monoterpenes / pharmacology
  • TRPV Cation Channels / agonists
  • TRPV Cation Channels / metabolism*
  • Xenopus

Substances

  • Boron Compounds
  • DNA, Complementary
  • Monoterpenes
  • TRPV Cation Channels
  • Trpv3 protein, mouse
  • Camphor
  • 2-aminoethoxydiphenyl borate
  • Cysteine
  • Calcium
  • 2-methyl-5-(1-methylethenyl)cyclohexanol