Inhibition by dexamethasone of beta 3-adrenergic receptor responsiveness in 3T3-F442A adipocytes. Evidence for a transcriptional mechanism.
Modulation of beta 3-adrenergic receptor (beta 3AR) expression by dexamethasone was investigated in the murine 3T3-F442A adipocytic cell line. In untreated cells, a major population of binding sites (62,000-114,000 sites/cell) of low affinity for (-)-[3H] CGP12177 and (-)-[125I]iodocyanopindolol (corresponding to the beta 3AR subtype) was present along with a minor population (6,500-8,000 sites/cell) of sites of high affinity for the radioligands (corresponding to a mixture of the beta 1 and beta 2AR subtypes). Long-term exposure of the cells to 250 nM dexamethasone led to a sharp decrease in beta 3AR density (less than 5,000 sites/cell) which paralleled a diminished potency of the beta 3AR-selective agonists BRL37344 and CGP12177 to stimulate the production of intracellular cAMP. Analysis of RNA by polymerase chain reaction and nuclear run-on assays indicated that dexamethasone inhibited the synthesis of beta 3AR mRNA, resulting in 4-8-fold decrease in the steady-state levels of this mRNA. The down-regulation of beta 3AR protein and cellular mRNA appeared to be mediated by the receptor for glucocorticoids as assessed by the antagonistic action of the anti-glucocorticoid RU38486.
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U 282 Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Hôpital Henri Mondor, Créteil, France.
Baude
B
B
Krief
S
S
Strosberg
A D
AD
Pairault
J
J
Emorine
L J
LJ
D016475:3T3 Cells; D000262:Adenylyl Cyclases / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects / Q000502:physiology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004983:Ethanolamines / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D015735:Mifepristone / Q000494:pharmacology; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D016133:Polymerase Chain Reaction; D011374:Progesterone / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D015735:Mifepristone; D011374:Progesterone; C057368:BRL 37344; D012313:RNA; D003907:Dexamethasone; D000262:Adenylyl Cyclases; D007545:Isoproterenol; C033394:CGP 12177