Essential role of beta-adrenergic receptor kinase 1 in cardiac development and function.


The beta-adrenergic receptor kinase 1 (beta ARK1) is a member of the G protein-coupled receptor kinase (GRK) family that mediates the agonist-dependent phosphorylation and desensitization of G protein-coupled receptors. We have cloned and disrupted the beta ARK1 gene in mice by homologous recombination. No homozygote beta ARK1-/- embryos survive beyond gestational day 15.5. Prior to gestational day 15.5, beta ARK1-/- embryos display pronounced hypoplasia of the ventricular myocardium essentially identical to the "thin myocardium syndrome" observed upon gene inactivation of several transcription factors (RXR alpha, N-myc, TEF-1, WT-1). Lethality in beta ARK1-/- embryos is likely due to heart failure as they exhibit a > 70% decrease in cardiac ejection fraction determined by direct in utero intravital microscopy. These results along with the virtual absence of endogenous GRK activity in beta ARK1-/- embryos demonstrate that beta ARK1 appears to be the predominant GRK in early embryogenesis and that it plays a fundamental role in cardiac development.







Howard Allan Rockman

Edward S. Orgain Distinguished Professor of Cardiology, in the School of Medicine

Rockman Lab: Molecular Mechanisms of Hypertrophy and Heart Failure

Overall Research Direction: The major focus of this laboratory is to understand the molecular mechanisms of hypertrophy and heart failure. My laboratory uses a strategy that combines state of the art molecular techniques to generate transgenic and gene targeted mouse models, combined with sophisticated physiologic measures of in vivo cardiac function. In this manner, candidate molecules are either selectively overexpressed in the mouse heart or genes ablated followed by an in-depth analysis of the physiological phenotype. To model human cardiac disease, we have created several models of cardiac overload in the mouse using both microsurgical techniques and genetic models of cardiac dysfunction.

Areas of Research
1) Signaling: G protein-coupled receptor signaling in hypertrophy and heart failure focusing on the concept of biased signaling of 7 transmembrane receptors.

2) Molecular physiology: In depth physiological analysis of cardiac function in genetically altered mice to understand the role of G protein-coupled receptor signaling pathways on the development of heart failure in vivo.

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