title: Sensitivities of Two Zebrafish TRPA1 Paralogs to Chemical and Thermal Stimuli Analyzed in Heterologous Expression Systems.
abstract: Transient receptor potential A1 (TRPA1) is the only member of the mouse, chick, and frog TRPA family, whereas 2 paralogs (zTRPA1a and zTRPA1b) are present in zebrafish. We herein investigated functional differences in the 2 zebrafish TRPA1s. HEK293T cells were used as heterologous expression systems, and the sensitivities of these cells to 4 chemical irritants (allyl isothiocyanate [AITC], caffeine, auto-oxidized epigallocatechin gallate [EGCG], and hydrogen peroxide [H2O2]) were compared with Ca(2+) imaging techniques. Sensitivities to the activators for AITC, oxidized EGCG, and H2O2 were higher in cells expressing zTRPA1a than in those expressing zTRPA1b, whereas caffeine appeared to activate both cells equally. We also characterized the thermal sensitivity of Xenopus oocytes expressing each TRPA1 electrophysiologically using a 2-electrode voltage clamp. Although endogenous currents induced by a cold stimulation were observed in control oocytes in some batches, oocytes expressing zTRPA1b showed significantly stronger cold- and heat-induced responses. However, significant thermal activation was not observed in oocytes expressing zTRPA1a. The results obtained using in vitro expression systems suggest that zTRPA1a is specialized for chemical sensing, whereas zTRPA1b responds to thermal stimuli. Furthermore, characterization of the chimeric molecule of TRPA1a and 1b revealed the importance of the N-terminal region in chemical and thermal sensing by zTRPA1s.
authors.affiliation: Department of Animal Bio-Science, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama-shi, Shiga 526-0829, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Oda
authors.affiliation: Department of Animal Bio-Science, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama-shi, Shiga 526-0829, Japan.
authors.forename: Mako
authors.initials: M
authors.lastname: Kurogi
authors.affiliation: Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Nishigohnaka38, Myodaiji, Okazaki, Aichi 444-8585, Japan and Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0155, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kubo
authors.affiliation: Department of Animal Bio-Science, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama-shi, Shiga 526-0829, Japan, o_saito@nagahama-i-bio.ac.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Saitoh
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism*; D007509:Irritants / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D000074025:TRPA1 Cation Channel; D013696:Temperature; D050051:Transient Receptor Potential Channels / Q000737:chemistry / Q000378:metabolism*; D015027:Zebrafish / Q000502:physiology*; D029961:Zebrafish Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D007509:Irritants; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels; D029961:Zebrafish Proteins; C494579:trpa1a protein, zebrafish; D006861:Hydrogen Peroxide; D002118:Calcium
keywords: allyl isothiocyanate; channel; neuron; thermosensing; transient receptor potential