Hybrid transgenic mice reveal in vivo specificity of G protein-coupled receptor kinases in the heart.
Abstract
G protein-coupled receptor kinases (GRKs) phosphorylate activated G protein-coupled
receptors, including alpha(1B)-adrenergic receptors (ARs), resulting in desensitization.
In vivo analysis of GRK substrate selectivity has been limited. Therefore, we generated
hybrid transgenic mice with myocardium-targeted overexpression of 1 of 3 GRKs expressed
in the heart (GRK2 [commonly known as the beta-AR kinase 1], GRK3, or GRK5) with concomitant
cardiac expression of a constitutively activated mutant (CAM) or wild-type alpha(1B)AR.
Transgenic mice with cardiac CAMalpha(1B)AR overexpression had enhanced myocardial
alpha(1)AR signaling and elevated heart-to-body weight ratios with ventricular atrial
natriuretic factor expression denoting myocardial hypertrophy. Transgenic mouse hearts
overexpressing only GRK2, GRK3, or GRK5 had no hypertrophy. In hybrid transgenic mice,
enhanced in vivo signaling through CAMalpha(1B)ARs, as measured by myocardial diacylglycerol
content, was attenuated by concomitant overexpression of GRK3 but not GRK2 or GRK5.
CAMalpha(1B)AR-induced hypertrophy and ventricular atrial natriuretic factor expression
were significantly attenuated with either concurrent GRK3 or GRK5 overexpression.
Similar GRK selectivity was seen in hybrid transgenic mice with wild-type alpha(1B)AR
overexpression concurrently with a GRK. GRK2 overexpression was without effect on
any in vivo CAM or wild-type alpha(1B)AR cardiac phenotype, which is in contrast to
previously reported in vitro findings. Furthermore, endogenous myocardial alpha(1)AR
mitogen-activated protein kinase signaling in single-GRK transgenic mice also exhibited
selectivity, as GRK3 and GRK5 desensitized in vivo alpha(1)AR mitogen-activated protein
kinase responses that were unaffected by GRK2 overexpression. Thus, these results
demonstrate that GRKs differentially interact with alpha(1B)ARs in vivo such that
GRK3 desensitizes all alpha(1B)AR signaling, whereas GRK5 has partial effects and,
most interestingly, GRK2 has no effect on in vivo alpha(1B)AR signaling in the heart.
Type
Journal articleSubject
AnimalsAtrial Natriuretic Factor
Cardiomegaly
Cell Line
Cyclic AMP-Dependent Protein Kinases
Diglycerides
G-Protein-Coupled Receptor Kinase 3
G-Protein-Coupled Receptor Kinase 5
Gene Expression
Hybridization, Genetic
JNK Mitogen-Activated Protein Kinases
Mice
Mice, Transgenic
Mitogen-Activated Protein Kinases
Mutation
Myocardium
Protein-Serine-Threonine Kinases
RNA, Messenger
Receptors, Adrenergic, alpha
Transgenes
beta-Adrenergic Receptor Kinases
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Show full item recordScholars@Duke
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 Chancellor’s Distinguished Professor of Medicine and
Professor of Biochemistry and Chemistry at the Duke University Medical Center. He
has bee

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