title: Regulation of Ca v 3.1 channels by glucocorticoids.
abstract: The activity of low voltage-activated Ca(2+) (Ca(V)3) channels is tightly coupled to neurotransmitter and hormone secretion. Previous studies have shown that Ca(V)3 channels are regulated by glucocorticoids (GCs), though the mechanism underlying channel regulation remains unclear. Here, using the pituitary GH(3) cell line as a model, we investigated whether Ca(V)3 channel expression is under the control of GCs, and if their actions are mediated by transcriptional and/or post-transcriptional mechanisms. RT-PCR and western blot analyses showed that Ca(V)3.1 but not Ca(V)3.2 and Ca(V)3.3 channels is expressed in the GH(3) cells, and patch clamp recordings confirmed that Ca(2+) currents through low voltage-activated channels were decreased after chronic treatment with GCs. Consistent with this, total plasma membrane expression of Ca(V)3.1 protein as analyzed by cell-surface biotinylation assays and semi-quantitative western blotting was also down-regulated, while quantitative real-time RT-PCR analysis revealed a significant decrease of Ca(V)3.1 mRNA expression in the treated cells. In contrast, patch-clamp recordings on HEK-293 cells stably expressing recombinant Ca(V)3.1 channels showed that Ca(2+) currents were not affected by GC treatment. These results suggest that decreased transcription is a likely mechanism to explain the inhibitory actions of GCs on the functional expression of native Ca(V)3.1 channels.
authors.affiliation: Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-IPN, Mexico City, Mexico.
authors.forename: Traudy
authors.initials: T
authors.lastname: Avila
authors.forename: Oscar
authors.initials: O
authors.lastname: Hernández-Hernández
authors.forename: Angélica
authors.initials: A
authors.lastname: Almanza
authors.forename: Mario Bermúdez
authors.initials: MB
authors.lastname: de León
authors.forename: Mercedes
authors.initials: M
authors.lastname: Urban
authors.forename: Enrique
authors.initials: E
authors.lastname: Soto
authors.forename: Bulmaro
authors.initials: B
authors.lastname: Cisneros
authors.forename: Ricardo
authors.initials: R
authors.lastname: Felix
mesh_terms: D000818:Animals; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: C500994:Cacna1g protein, rat; D020747:Calcium Channels, T-Type; D005938:Glucocorticoids; D012333:RNA, Messenger