Hybrid transgenic mice reveal in vivo specificity of G protein-coupled receptor kinases in the heart.
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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.
Atrial Natriuretic Factor
Cyclic AMP-Dependent Protein Kinases
G-Protein-Coupled Receptor Kinase 3
G-Protein-Coupled Receptor Kinase 5
JNK Mitogen-Activated Protein Kinases
Mitogen-Activated Protein Kinases
Receptors, Adrenergic, alpha
beta-Adrenergic Receptor Kinases
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James B. Duke Professor of Medicine
The focus of work in this laboratory is on the elucidation of the molecular properties and regulatory mechanisms controlling the function of G protein-coupled receptors. As model systems we utilize the so called adrenergic receptors for adrenaline and related molecules. The goal is to learn the general principles of signal transduction from the outside to the inside of the cell which are involved in systems as diverse as sensory perception, neuro- transmitter and hormonal signaling. Stud
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Diversé-Pierluissi, M; Drazner, Mark H; Dyer, SL; Freedman, NJ; Lefkowitz, Robert J; Oppermann, M; Peppel, Karsten C (Proc Natl Acad Sci U S A, 1996-07-23)Guanine nucleotide-binding regulatory protein (G protein)-coupled receptor kinases (GRKs) constitute a family of serine/threonine kinases that play a major role in the agonist-induced phosphorylation and desensitization ...
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