1. Crosstalk between adenosine A1 and β1-adrenergic receptors regulates translocation of PKCε in isolated rat cardiomyocytes.
- Author
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Komatsu S, Dobson JG Jr, Ikebe M, Shea LG, and Fenton RA
- Subjects
- Adenosine analogs & derivatives, Adenosine pharmacology, Adenosine A1 Receptor Antagonists pharmacology, Adrenergic beta-1 Receptor Agonists pharmacology, Animals, Colforsin pharmacology, Cyclic AMP-Dependent Protein Kinases genetics, Cyclic AMP-Dependent Protein Kinases metabolism, Intracellular Signaling Peptides and Proteins pharmacology, Isoproterenol administration & dosage, Isoquinolines pharmacology, Membrane Proteins metabolism, Myocytes, Cardiac cytology, Organ Culture Techniques, Protein Kinase C-epsilon genetics, Protein Kinase Inhibitors pharmacology, Protein Transport drug effects, Protein Transport genetics, Rats, Rats, Sprague-Dawley, Receptor, Adenosine A1 genetics, Receptors, Adrenergic, beta-1 genetics, Signal Transduction, Sulfonamides pharmacology, Xanthines pharmacology, Adenosine metabolism, Myocardium metabolism, Myocytes, Cardiac metabolism, Protein Kinase C-epsilon metabolism, Receptor, Adenosine A1 metabolism, Receptors, Adrenergic, beta-1 metabolism
- Abstract
Adenosine A(1) receptor (A(1)R)-induced translocation of PKCε to transverse (t) tubular membranes in isolated rat cardiomyocytes is associated with a reduction in β(1)-adrenergic-stimulated contractile function. The PKCε-mediated activation of protein kinase D (PKD) by endothelin-1 is inhibited by β(1)-adrenergic stimulated protein kinase A (PKA) suggesting a similar mechanism of A(1)R signal transduction modulation by adrenergic agonists may exist in the heart. We have investigated the influence of β(1)-adrenergic stimulation on PKCε translocation elicited by A(1)R. Immunofluorescence imaging and Western blotting with PKCε and β-COP antibodies were used to quantify the co-localization of PKCε and t-tubular structures in isolated rat cardiomyocytes. The A(1)R agonist CCPA increased the co-localization of PKCε and t-tubules as detected by imaging. The β(1)-adrenergic receptor agonist isoproterenol (ISO) inhibited this effect of CCPA. Forskolin, a potent activator of PKA, mimicked, and H89, a pharmacological PKA inhibitor, and PKI, a membrane-permeable PKA peptide PKA inhibitor, attenuated the negative effect of ISO on the A(1)R-mediated PKCε translocation. Western blotting with isolated intact hearts revealed an increase in PKCε/β-COP co-localization induced by A(1)R. This increase was attenuated by the A(1)R antagonist DPCPX and ISO. The ISO-induced attenuation was reversed by H89. It is concluded that adrenergic stimulation inhibits A(1)R-induced PKCε translocation to the PKCε anchor site RACK2 constituent of a coatomer containing β-COP and associated with the t-tubular structures of the heart. In that this translocation has been previously associated with the antiadrenergic property of A(1)R, it is apparent that the interactive effects of adenosine and β(1)-adrenergic agonists on function are complex in the heart., (Copyright © 2011 Wiley Periodicals, Inc.)
- Published
- 2012
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