title: Copper elicits an increase in cytosolic free calcium in cultured tobacco cells.
abstract: At concentrations greater than 0.1 mM, CuSO(4) provoked a rapid and sustained increase in the cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)), in tobacco suspension culture cells expressing apoaequorin, a Ca(2+)-sensitive photoprotein. The increase was suppressed by treatment with LaCl(3), indicating that the increase is due to an influx of Ca(2+) from the apoplast through plasma membrane Ca(2+) channels. Although stimulation of H(2)O(2) production upon the CuSO(4) treatment (0.1 mM) was observed, treatment with catalase did not inhibit the increase in [Ca(2+)](cyt), and treatment with H(2)O(2) dose-dependently suppressed or delayed the increase. These results suggested that active oxygen species generated through copper-mediated reactions, or copper-mediated oxidative damages to plasma membrane, are not responsible for the increase. Treatment with sulfhydryl reagents, which alkylate or oxidize thiol groups, or acidification of the culture medium suppressed the increase in [Ca(2+)](cyt). These results demonstrated that copper causes an influx of Ca(2+) through plasma membrane Ca(2+) channels, and that plasma membrane thiol groups play an important role in activating the Ca(2+) channels.
authors.affiliation: Laboratory for Adaptation and Resistance, Environmental Plant Research Group, Plant Science Center, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Inoue
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kudo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kamada
authors.forename: Makoto
authors.initials: M
authors.lastname: Kimura
authors.forename: Isamu
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hamamoto
mesh_terms: D000331:Aequorin / Q000378:metabolism; D001059:Apoproteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D019327:Copper Sulfate / Q000378:metabolism*; D003470:Culture Media; D003600:Cytosol / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D018384:Oxidative Stress; D011994:Recombinant Proteins / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology / Q000378:metabolism*
chemical_list: D001059:Apoproteins; D015220:Calcium Channels; D003470:Culture Media; D011994:Recombinant Proteins; D013438:Sulfhydryl Compounds; C060014:apoaequorin; D000331:Aequorin; D006861:Hydrogen Peroxide; D002374:Catalase; D019327:Copper Sulfate; D002118:Calcium