title: Crosstalk between adenosine A1 and β1-adrenergic receptors regulates translocation of PKCε in isolated rat cardiomyocytes.
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.
authors: Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA. Satoshi.Komatsu@umassmed.edu
authors: Satoshi
authors: S
authors: Komatsu
authors: James G
authors: JG
authors: Dobson
authors: Mitsuo
authors: M
authors: Ikebe
authors: Lynne G
authors: LG
authors: Shea
authors: Richard A
authors: RA
authors: Fenton
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D058916:Adenosine A1 Receptor Antagonists / Q000494:pharmacology; D058665:Adrenergic beta-1 Receptor Agonists / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology; D007545:Isoproterenol / Q000008:administration & dosage; D007546:Isoquinolines / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D009924:Organ Culture Techniques; D051744:Protein Kinase C-epsilon / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000235:genetics / Q000378:metabolism*; D018342:Receptors, Adrenergic, beta-1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
chemical_list: D058916:Adenosine A1 Receptor Antagonists; D058665:Adrenergic beta-1 Receptor Agonists; C543179:Copb1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D007546:Isoquinolines; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D043682:Receptor, Adenosine A1; D018342:Receptors, Adrenergic, beta-1; D013449:Sulfonamides; D014970:Xanthines; C015482:protein kinase modulator; D005576:Colforsin; C058394:2-chloro-N(6)cyclopentyladenosine; C051360:1,3-dipropyl-8-cyclopentylxanthine; D017868:Cyclic AMP-Dependent Protein Kinases; D051744:Protein Kinase C-epsilon; D000241:Adenosine; D007545:Isoproterenol; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide