title: Dexamethasone rapidly induces Kv1.5 K+ channel gene transcription and expression in clonal pituitary cells.
abstract: Glucocorticoids specifically increase Kv1.5 K+ channel mRNA in normal and clonal (GH3) rat pituitary cells. Here, we demonstrate that dexamethasone, a glucocorticoid agonist, rapidly induces Kv1.5 gene transcription, but does not affect Kv1.5 mRNA turnover (t1/2 approximately 0.5 hr) in GH3 cells. Immunoblots indicate that the steroid also increases the expression of the 76 kd Kv1.5 protein approximately 3-fold within 12 hr without altering its half-life (t1/2 approximately 4 hr). In contrast, Kv1.4 protein expression is unaffected. Finally, we find that the induction of Kv1.5 protein is associated with an increase in a noninactivating component of the voltage-gated K+ current. Our results indicate that hormones and neurotransmitters may act within hours to regulate excitability by controlling K+ channel gene expression.
authors.affiliation: Department of Pharmacology, University of Pittsburgh, Pennsylvania 15261.
authors.forename: K
authors.initials: K
authors.lastname: Takimoto
authors.forename: A F
authors.initials: AF
authors.lastname: Fomina
authors.forename: R
authors.initials: R
authors.lastname: Gealy
authors.forename: J S
authors.initials: JS
authors.lastname: Trimmer
authors.forename: E S
authors.initials: ES
authors.lastname: Levitan
mesh_terms: D000818:Animals; D002999:Clone Cells; D003907:Dexamethasone / Q000494:pharmacology*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D015221:Potassium Channels; D012333:RNA, Messenger; D003907:Dexamethasone