Dexamethasone rapidly induces Kv1.5 K+ channel gene transcription and expression in clonal pituitary cells.
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.
Takimoto
K
K
Department of Pharmacology, University of Pittsburgh, Pennsylvania 15261.
Fomina
A F
AF
Gealy
R
R
Trimmer
J S
JS
Levitan
E S
ES
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*
D015221:Potassium Channels; D012333:RNA, Messenger; D003907:Dexamethasone