title: Human dental pulp fibroblasts express the "cold-sensing" transient receptor potential channels TRPA1 and TRPM8.
abstract: BACKGROUND
  Transient receptor potential (TRP) channels comprise a group of nonselective calcium-permeable cationic channels, which are polymodal sensors of environmental stimuli such as thermal changes and chemicals. TRPM8 and TRPA1 are cold-sensing TRP channels activated by moderate cooling and noxious cold temperatures, respectively. Both receptors have been identified in trigeminal ganglion neurones, and their expression in nonneuronal cells is now the focus of much interest. The aim of this study was to investigate the molecular and functional expression of TRPA1 and TRPM8 in dental pulp fibroblasts.
  
  
  METHODS
  Human dental pulp fibroblasts were derived from healthy molar teeth. Gene and protein expression was determined by polymerase chain reaction and Western blotting. Cellular localization was investigated by immunohistochemistry, and TRP functionality was determined by Ca(2+) microfluorimetry.
  
  
  RESULTS
  Polymerase chain reaction and Western blotting showed gene and protein expression of both TRPA1 and TRPM8 in fibroblast cells in culture. Immunohistochemistry studies showed that TRPA1 and TRPM8 immunoreactivity co-localized with the human fibroblast surface protein. In Ca(2+) microfluorimetry studies designed to determine the functionality of TRPA1 and TRPM8 in pulp fibroblasts, we showed increased intracellular calcium ([Ca(2+)](i)) in response to the TRPM8 agonist menthol, the TRPA1 agonist cinnamaldehyde, and to cool and noxious cold stimuli, respectively. The responses to agonists and thermal stimuli were blocked in the presence of specific TRPA1 and TRPM8 antagonists.
  
  
  CONCLUSIONS
  Human dental pulp fibroblasts express TRPA1 and TRPM8 at the molecular, protein, and functional levels, indicating a possible role for fibroblasts in mediating cold responses in human teeth.
authors.affiliation: School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Ikhlas A
authors.initials: IA
authors.lastname: El Karim
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Linden
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Curtis
authors.forename: Imad
authors.initials: I
authors.lastname: About
authors.forename: Mary K
authors.initials: MK
authors.lastname: McGahon
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Irwin
authors.forename: Simon A
authors.initials: SA
authors.lastname: Killough
authors.forename: Fionnuala T
authors.initials: FT
authors.lastname: Lundy
mesh_terms: D000083:Acetanilides / Q000494:pharmacology; D000171:Acrolein / Q000031:analogs & derivatives / Q000494:pharmacology; D000328:Adult; D015153:Blotting, Western; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000032:analysis*; D020013:Calcium Signaling / Q000187:drug effects; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D003080:Cold Temperature; D003592:Cytophotometry; D003782:Dental Pulp / Q000166:cytology*; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000032:analysis; D008610:Menthol / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000819:agonists / Q000032:analysis* / Q000037:antagonists & inhibitors; D009619:Nociceptors / Q000166:cytology* / Q000187:drug effects; D010812:Physical Stimulation; D011687:Purines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000074025:TRPA1 Cation Channel; D050053:TRPM Cation Channels / Q000819:agonists / Q000032:analysis* / Q000037:antagonists & inhibitors; D013697:Thermosensing / Q000502:physiology; D050051:Transient Receptor Potential Channels / Q000819:agonists / Q000032:analysis* / Q000037:antagonists & inhibitors; D055815:Young Adult
chemical_list: C552888:2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide; D000083:Acetanilides; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011687:Purines; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human; D050051:Transient Receptor Potential Channels; D008610:Menthol; D000171:Acrolein; C071423:capsazepine; D002211:Capsaicin; C012843:cinnamaldehyde