cAMP stimulates transcription of the beta 2-adrenergic receptor gene in response to short-term agonist exposure.
Abstract
In addition to conveying cellular responses to an effector molecule, receptors are
often themselves regulated by their effectors. We have demonstrated that epinephrine
modulates both the rate of transcription of the beta 2-adrenergic receptor (beta 2AR)
gene and the steady-state level of beta 2AR mRNA in DDT1MF-2 cells. Short-term (30
min) exposure to epinephrine (100 nM) stimulates the rate of beta 2AR gene transcription,
resulting in a 3- to 4-fold increase in steady-state beta 2AR mRNA levels. These effects
are mimicked by 1 mM N6,O2'-dibutyryladenosine 3',5'-cyclic monophosphate (Bt2cAMP)
or foskolin but not by phorbol esters. The half-life of the beta 2AR mRNA after addition
of actinomycin D (46.7 +/- 10.2 min; mean +/- SEM; n = 5) remained unchanged after
30 min of epinephrine treatment (46.8 +/- 10.6 min; mean +/- SEM; n = 4), indicating
that a change in transcription rate is the predominant factor responsible for the
increase of beta 2AR mRNA. Whereas brief exposure to epinephrine or Bt2cAMP does not
significantly affect the total number of cellular beta 2ARs (assessed by ligand binding),
continued exposure results in a gradual decline in beta 2AR number to approximately
20% (epinephrine) or approximately 45% (Bt2cAMP) of the levels in control cells by
24 hr. Similar decreases in agonist-stimulated adenylyl cyclase activity are observed.
This loss of receptors with prolonged agonist exposure is accompanied by a 50% reduction
in beta 2AR mRNA. Transfection of the beta 2AR promoter region cloned onto a reporter
gene (bacterial chloramphenicol acetyltransferase) allowed demonstration of a 2- to
4-fold induction of transcription by agents that elevate cAMP levels, such as forskolin
or phosphodiesterase inhibitors. These results establish the presence of elements
within the proximal promoter region of the beta 2AR gene responsible for the transcriptional
enhancing activity of cAMP and demonstrate that beta 2AR gene expression is regulated
by a type of feedback mechanism involving the second messenger cAMP.
Type
Journal articleSubject
1-Methyl-3-isobutylxanthineAnimals
Base Sequence
Cell Line
Cell Membrane
Colforsin
Cricetinae
Cyclic AMP
Epinephrine
Genes
Glioma
Kinetics
RNA, Messenger
Rats
Receptors, Adrenergic, beta
Tetradecanoylphorbol Acetate
Theophylline
Transcription, Genetic
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https://hdl.handle.net/10161/7867Collections
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Show full item recordScholars@Duke
Marc G. Caron
James B. Duke Distinguished Professor of Cell Biology
Studies of the mechanisms of action and regulation of hormones and neurotransmitters
at the cellular and molecular levels constitute the main goals our of research activities.
G protein-coupled receptors (GPCR) mediate the actions of signaling molecules from
unicellular organisms to man. We have used adrenergic and dopamine receptors to characterize
the structure/function and regulation mechanisms of these prototypes of G protein-coupled
receptors. Another approach has been to characterize
This author no longer has a Scholars@Duke profile, so the information shown here reflects
their Duke status at the time this item was deposited.
Robert J. Lefkowitz
The Chancellor's Distinguished Professor of Medicine
Dr. Lefkowitz’s memoir, A Funny Thing Happened on the Way to Stockholm, recounts his
early career as a cardiologist and his transition to biochemistry, which led to his
Nobel Prize win.
Robert J. Lefkowitz, M.D. is James B. Duke Professor of Medicine and Professor of
Biochemistry and Chemistry at the Duke University Medical Center. He has been an Investigator
of the
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