Dexamethasone rapidly increases calcium channel subunit messenger RNA expression and high voltage-activated calcium current in clonal pituitary cells.
Glucocorticoid hormones increase voltage-gated Ca(2)+ current density in clonal pituitary cells. To test whether these steroids might stimulate expression of Ca(2)+ channel genes, messenger RNase protection assays were used to measure alpha IC and alpha ID RNAs that encode pore-forming subunits of L-type Ca2+ channels. We show here that dexamethasone rapidly increases alpha IC messenger RNA expression without affecting alpha ID messenger RNA level. This up-regulation of channel messenger RNA is also produced by natural glucocorticoids and is blocked by the glucocorticoid antagonist Ru48386. The up-regulation of the channel subunit messenger RNA expression is associated with an increase in high voltage-activated Ca(2)+ current density. Thus, glucocorticoids may produce a long-term effect on Ca(2)+ homeostasis in clonal pituitary cells by differentially regulating expression of Ca(2)+ channel subunit genes.
Fomina
A F
AF
Department of Pharmacology, University of Pittsburgh, PA 15261, USA.
Levitan
E S
ES
Takimoto
K
K
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects* / Q000502:physiology; D003907:Dexamethasone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D010902:Pituitary Gland / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism
D015220:Calcium Channels; D012333:RNA, Messenger; D003907:Dexamethasone