title: Identification of molecular determinants for a potent mammalian TRPA1 antagonist by utilizing species differences.
abstract: The transient receptor potential A1 (TRPA1) receptor is a member of the TRP family and an excitatory nonselective cation channel. An increasing body of evidence suggests that TRPA1 acts as a nociceptor for various chemicals and physical stimuli. Thus, many TRPA1 antagonists have been developed as analgesic agents. Recently, we found that AP18, a mammalian TRPA1 antagonist, does not inhibit heterologously expressed western clawed frog TRPA1 (fTRPA1). Here, we show that fTRPA1 is also insensitive to A967079, one of the most potent mammalian TRPA1 antagonists. Neither heterologously nor endogenously expressed fTRPA1 was inhibited by A967079 upon activation by TRPA1 agonists. Mutant channel analyses revealed that two specific amino acid residues located within the putative fifth transmembrane domain were involved in the inhibitory action of A967079. Our findings and previous reports based on species differences in the sensitivity to TRPA1 antagonists provide novel insights into the structure-function relationship of TRPA1 and supply useful information in the search for new analgesic medicines targeting TRPA1.
authors.affiliation: Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, 680-8553, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Nakatsuka
authors.forename: Rupai
authors.initials: R
authors.lastname: Gupta
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.forename: Nagako
authors.initials: N
authors.lastname: Banzawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Tominaga
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohta
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000818:Animals; D001665:Binding Sites; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010091:Oximes / Q000494:pharmacology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013045:Species Specificity; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
chemical_list: C560402:A 967079; D018712:Analgesics, Non-Narcotic; D015220:Calcium Channels; D009419:Nerve Tissue Proteins; D010091:Oximes; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050051:Transient Receptor Potential Channels