title: Dex-ras1 and serum- and glucocorticoid-inducible protein kinase 1: regulation of expression by dexamethasone in HEK293 cells.
abstract: The molecular and cellular basis of the psychotropic actions of adrenal corticosteroids is poorly understood. Previously, we reported that modulation of large conductance Ca2+-activated potassium channel (BK-channel) function by glucocorticoids can be recapitulated in human embryonic kidney293 (HEK293) cells (J Physiol 537:57, 2001). In the present paper, we examined the effect of dexamethasone on the expression of candidate mediator proteins of glucocorticoid action, dex-ras1 and serum and glucocorticoid inducible protein kinase 1 (SGK), in HEK293 cells. Dex-ras1 mRNA was readily detectable under basal conditions however, no changes of dex-ras1 mRNA expression occurred upon exposure to 100 nM of dexamethasone for 2 h. In contrast, a 2.5-fold increase of SGK mRNA was found under similar conditions. Total levels of cellular SGK protein were unaltered upon exposure to dexamethasone, but a marked increase of SGK in a Triton-X100 insoluble fraction was observed. BK-channel alpha-subunits could not be co-immunoprecipitated with SGK. In summary, SGK, but not dex-ras1, mRNA is rapidly induced by glucocorticoid stimulation in HEK293 cells. However, there appears to be no direct protein-protein interaction between SGK and BK-channel alpha-subunits.
authors.affiliation: Membrane Biology Group, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK. gattarzadeh@yahoo.com
authors.forename: Ghassem
authors.initials: G
authors.lastname: Attarzadeh-Yazdi
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Shipston
authors.forename: Ferenc A
authors.initials: FA
authors.lastname: Antoni
mesh_terms: D015152:Blotting, Northern; D045744:Cell Line, Tumor; D003907:Dexamethasone / Q000494:pharmacology*; D017930:Genes, Reporter / Q000187:drug effects / Q000235:genetics; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D047468:Immunoprecipitation; D008156:Luciferases / Q000235:genetics; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018631:ras Proteins / Q000235:genetics*; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D003907:Dexamethasone; D017874:Immediate-Early Proteins; D008156:Luciferases; D024681:Potassium Channels, Calcium-Activated; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D018631:ras Proteins; D000099184:Serum-Glucocorticoid Regulated Kinases; C400132:RASD1 protein, human