Dex-ras1 and serum- and glucocorticoid-inducible protein kinase 1: regulation of expression by dexamethasone in HEK293 cells

Neurochem Res. 2008 Apr;33(4):609-13. doi: 10.1007/s11064-007-9516-5. Epub 2007 Nov 6.

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.

MeSH terms

  • Blotting, Northern
  • Cell Line, Tumor
  • Dexamethasone / pharmacology*
  • Genes, Reporter / drug effects
  • Genes, Reporter / genetics
  • Humans
  • Immediate-Early Proteins / genetics*
  • Immunoprecipitation
  • Luciferases / genetics
  • Potassium Channels, Calcium-Activated / drug effects
  • Protein Serine-Threonine Kinases / genetics*
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • ras Proteins / genetics*

Substances

  • Immediate-Early Proteins
  • Potassium Channels, Calcium-Activated
  • RASD1 protein, human
  • RNA, Messenger
  • Dexamethasone
  • Luciferases
  • Protein Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase
  • ras Proteins