Potentiation of beta-adrenergic signaling by adenoviral-mediated gene transfer in adult rabbit ventricular myocytes.

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1997-01-15

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Abstract

Our laboratory has been testing the hypothesis that genetic modulation of the beta-adrenergic signaling cascade can enhance cardiac function. We have previously shown that transgenic mice with cardiac overexpression of either the human beta2-adrenergic receptor (beta2AR) or an inhibitor of the beta-adrenergic receptor kinase (betaARK), an enzyme that phosphorylates and uncouples agonist-bound receptors, have increased myocardial inotropy. We now have created recombinant adenoviruses encoding either the beta2AR (Adeno-beta2AR) or a peptide betaARK inhibitor (consisting of the carboxyl terminus of betaARK1, Adeno-betaARKct) and tested their ability to potentiate beta-adrenergic signaling in cultured adult rabbit ventricular myocytes. As assessed by radioligand binding, Adeno-beta2AR infection led to approximately 20-fold overexpression of beta-adrenergic receptors. Protein immunoblots demonstrated the presence of the Adeno-betaARKct transgene. Both transgenes significantly increased isoproterenol-stimulated cAMP as compared to myocytes infected with an adenovirus encoding beta-galactosidase (Adeno-betaGal) but did not affect the sarcolemmal adenylyl cyclase response to Forskolin or NaF. beta-Adrenergic agonist-induced desensitization was significantly inhibited in Adeno-betaARKct-infected myocytes (16+/-2%) as compared to Adeno-betaGal-infected myocytes (37+/-1%, P < 0.001). We conclude that recombinant adenoviral gene transfer of the beta2AR or an inhibitor of betaARK-mediated desensitization can potentiate beta-adrenergic signaling.

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10.1172/JCI119157

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Drazner, MH, KC Peppel, S Dyer, AO Grant, WJ Koch and RJ Lefkowitz (1997). Potentiation of beta-adrenergic signaling by adenoviral-mediated gene transfer in adult rabbit ventricular myocytes. J Clin Invest, 99(2). pp. 288–296. 10.1172/JCI119157 Retrieved from https://hdl.handle.net/10161/7831.

This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.

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Grant

Augustus Oliver Grant

Professor of Medicine

This laboratory seeks to understand the molecular events that control excitation in cardiac muscle and the mechanisms by which excitation is modified by drugs. The experimental models include the isolated cardiac myocyte, the frog oocyte and mammalian cells expressing mRNA transcripts of wild-type and mutant channels. The experimental techniques include DNA and RNA manipulation, whole cell voltage clamping and the extracellular patch clamping. The current focus of the laboratory is the voltage gated sodium channel. The problems under study include:

1) The functional effects of the derangements occurring during
myocardial ischemia on channel function.
2) The mechanisms of blockade of channels by antiarrhythmic drugs.
3) The relationship between channel structure and antiarrhythmic drug
binding.
4) The development of models to describe the interaction of anti-
arrhythmic drugs with membrane channels.

These studies should provide a clearer understanding of the cellular basis of cardiac arrhythmias and the mechanisms by which they are terminated by drug.

Lefkowitz

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 been an Investigator of the Howard Hughes Medical Institute since 1976. Dr. Lefkowitz began his research career in the late 1960’s and early 1970’s when there was not a clear consensus that specific receptors for drugs and hormones even existed. His group spent 15 difficult years developing techniques for labeling the receptors with radioactive drugs and then purifying the four different receptors that were known and thought to exist for adrenaline, so called adrenergic receptors. In 1986 Dr. Lefkowitz transformed the understanding of what had by then become known as G protein coupled receptors because of the way the receptor signal for the inside of a cell through G proteins, when he and his colleagues cloned the gene for the beta2-adrenergic receptor. They immediately recognized the similarity to a molecule called rhodopsin which is essentially a light receptor in the retina. This unexpected finding established the beta receptor and rhodopsin as the first member of a new family of proteins. Because each has a peptide structure, which weaves across the cell membrane seven times, these receptors are referred to as seven transmembrane receptors. This super family is now known to be the largest, most diverse and most therapeutically accessible of all the different kinds of cellular receptors. There are almost a thousand members of this receptor family and they regulate virtually all known physiological processes in humans. They include the receptors not only to numerous hormones and neurotransmitters but for the receptors which mediate the senses of sweet and bitter taste and smell amongst many others. Dr. Lefkowitz also discovered the mechanism by which receptor signaling is turned off, a process known as desensitization. Dr. Lefkowitz work was performed at the most fundamental and basic end of the research spectrum and has had remarkable consequences for clinical medicine. Today, more than half of all prescription drug sales are of drugs that target either directly or indirectly the receptors discovered by Dr. Lefkowitz and his trainees. These include amongst many others beta blockers, angiotensin receptor blockers or ARBs and antihistamines. Over the past decade he has discovered novel mechanisms by which the receptors function which may lead to the development of an entirely new class of drugs called “biased agonists”. Several such compounds are already in advanced stages of clinical testing. Dr. Lefkowitz has received numerous honors and awards, including the National Medal of Science, the Shaw Prize, the Albany Prize, and the 2012 Nobel Prize in Chemistry. He was elected to the USA National Academy of Sciences in 1988, the Institute of Medicine in 1994, and the American Academy of Arts and Sciences in 1988.


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