title: Molecular basis determining inhibition/activation of nociceptive receptor TRPA1 protein: a single amino acid dictates species-specific actions of the most potent mammalian TRPA1 antagonist.
abstract: The transient receptor potential ankyrin 1 (TRPA1) is a Ca(2+)-permeable, nonselective cation channel mainly expressed in a subset of nociceptive neurons. TRPA1 functions as a cellular sensor detecting mechanical, chemical, and thermal stimuli. Because TRPA1 is considered to be a key player in nociception and inflammatory pain, TRPA1 antagonists have been developed as analgesic agents. Recently, by utilizing species differences, we identified the molecular basis of the antagonistic action of A967079, one of the most potent mammalian TRPA1 antagonists. Here, we show a unique effect of A967079 on TRPA1 from diverse vertebrate species, i.e. it acts as an agonist but not as an antagonist for chicken and frog TRPA1s. By characterizing chimeric channels of human and chicken TRPA1s, as well as point mutants, we found that a single specific amino acid residue located within the putative fifth transmembrane domain was involved in not only the stimulatory but also the inhibitory actions of A967079. AP18, structurally related to A967079, exerted similar pharmacological properties to A967079. Our findings and previous reports on species differences in the sensitivity to TRPA1 antagonists supply useful information in the search for novel analgesic medicines targeting TRPA1.
authors.affiliation: Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, 680-8553.
authors.forename: Nagako
authors.initials: N
authors.lastname: Banzawa
authors.affiliation: Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki 444-8787, and.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.affiliation: Laboratory of Biological Chemistry, Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Imagawa
authors.affiliation: Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki 444-8787, and.
authors.forename: Makiko
authors.initials: M
authors.lastname: Kashio
authors.affiliation: Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, 680-8553.
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki 444-8787, and.
authors.forename: Makoto
authors.initials: M
authors.lastname: Tominaga
authors.affiliation: Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, 680-8553,. Electronic address: tohta@muses.tottori-u.ac.jp.
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohta
mesh_terms: D000700:Analgesics; D000818:Animals; D002118:Calcium / Q000737:chemistry; D015220:Calcium Channels / Q000737:chemistry*; D002642:Chick Embryo; D002645:Chickens; D005727:Ganglia, Spinal / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D009474:Neurons / Q000378:metabolism; D010091:Oximes / Q000737:chemistry; D018408:Patch-Clamp Techniques; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013045:Species Specificity; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels / Q000037:antagonists & inhibitors* / Q000737:chemistry*
chemical_list: C560402:A 967079; D000700:Analgesics; D015220:Calcium Channels; D009419:Nerve Tissue Proteins; D010091:Oximes; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse; D002118:Calcium
keywords: Calcium Imaging; Dorsal Root Ganglia; Neuron; Pain; Patch Clamp; Transient Receptor Potential Channels (TRP Channels)