title: Destabilization of Na(v)1.7 sodium channel alpha-subunit mRNA by constitutive phosphorylation of extracellular signal-regulated kinase: negative regulation of steady-state level of cell surface functional sodium channels in adrenal chromaffin cells.
abstract: In cultured bovine adrenal chromaffin cells expressing Na(v)1.7 isoform of voltage-dependent Na(+) channels, treatment (> or = 6 h) with serum deprivation, PD98059, or U0126 increased cell surface [(3)H]saxitoxin ([(3)H]STX) binding by approximately 58% (t(1/2) = 12.5 h), with no change in the K(d) value. Immunoblot analysis showed that either treatment attenuated constitutive phosphorylation of extracellular signal-regulated kinase (ERK) 1 and ERK2 but not of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK) 1 and JNK2. The increase of [(3)H]STX binding and the attenuated phosphorylation of ERK1 and ERK2 returned to the control nontreated levels after the addition of serum or the washout of PD98059- or U0126-treated cells. Simultaneous treatment of serum deprivation with PD98059 or U0126 did not produce an additional increasing effect on [(3)H]STX binding, compared with either treatment alone. In cells subjected to either treatment, veratridine-induced maximum (22)Na(+) influx was augmented by approximately 47%, with no change in the EC(50) value; Ptychodiscus brevis toxin-3 enhanced veratridine-induced (22)Na(+) influx by 2-fold, as in nontreated cells. Serum deprivation, PD98059, or U0126 increased Na(+) channel alpha- but not beta(1)- subunit mRNA level by approximately 50% between 3 and 24 h; cycloheximide, an inhibitor of protein synthesis, increased alpha-subunit mRNA level and nullified additional increasing effect of either treatment on alpha-subunit mRNA level. Either treatment prolonged half-life of alpha-subunit mRNA from 17.5 to approximately 26.3 h without altering alpha-subunit gene transcription. Thus, constitutively phosphorylated/activated ERK destabilizes Na(+) channel alpha-subunit mRNA via translational event, which negatively regulates steady-state level of alpha-subunit mRNA and cell surface expression of functional Na(+) channels.
authors.affiliation: Department of Pharmacology, Miyazaki Medical College, Kiyotake, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yanagita
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Uezono
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yokoo
authors.forename: Takashi
authors.initials: T
authors.lastname: Sugano
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Saitoh
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Minami
authors.forename: Seiji
authors.initials: S
authors.lastname: Shiraishi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Wada
mesh_terms: D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002412:Cations; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000378:metabolism; D012530:Saxitoxin / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014316:Tritium; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D002070:Butadienes; D002412:Cations; D005419:Flavonoids; D009570:Nitriles; D021122:Protein Subunits; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D011978:Receptors, Nicotinic; D015222:Sodium Channels; C113580:U 0126; D014316:Tritium; D012530:Saxitoxin; D003513:Cycloheximide; D012964:Sodium; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one