Adenoprotection of the heart involves phospholipase C-induced activation and translocation of PKC-epsilon to RACK2 in adult rat and mouse

Am J Physiol Heart Circ Physiol. 2009 Aug;297(2):H718-25. doi: 10.1152/ajpheart.00247.2009. Epub 2009 Jun 12.

Abstract

Adenosine protects the heart from adrenergic overstimulation. This adenoprotection includes the direct anti-adrenergic action via adenosine A(1) receptors (A(1)R) on the adrenergic signaling pathway. An indirect A(1)R-induced attenuation of adrenergic responsiveness involves the translocation of PKC-epsilon to t-tubules and Z-line of cardiomyocytes. We investigated with sarcomere imaging, immunocytochemistry imaging, and coimmunoprecipitation (co-IP) whether A(1)R activation of PKC-epsilon induces the kinase translocation to receptor for activated C kinase 2 (RACK2) in isolated rat and mouse hearts and whether phospholipase C (PLC) is involved. Rat cardiomyocytes were treated with the A(1)R agonist chlorocyclopentyladenosine (CCPA) and exposed to primary PKC-epsilon and RACK2 antibodies with secondaries conjugated to Cy3 and Cy5 (indodicarbocyanine), respectively. Scanning confocal microscopy showed that CCPA caused PKC-epsilon to reversibly colocalize with RACK2 within 3 min. Additionally, rat and mouse hearts were perfused and stimulated with CCPA or phenylisopropyladenosine to activate A(1)R, or with phorbol 12-myristate 13-acetate to activate PKC. RACK2 was immunoprecipitated from heart extracts and resolved with SDS-PAGE. Western blotting showed that CCPA, phenylisopropyladenosine, and phorbol 12-myristate 13-acetate in the rat heart increased the PKC-epsilon co-IP with RACK2 by 186, 49, and >1,000%, respectively. The A(1)R antagonist 8-cyclopentyl-1,3-dipropylxanthine prevented the CCPA-induced co-IP with RACK2. In mouse hearts, CCPA increased the co-IP of PKC-epsilon with RACK2 by 61%. With rat cardiomyocytes, the beta-adrenergic agonist isoproterenol increased sarcomere shortening by 177%. CCPA reduced this response by 47%, an action inhibited by the PLC inhibitor U-73122 and 8-cyclopentyl-1,3-dipropylxanthine. In conclusion, A(1)R stimulation of the heart is associated with PLC-initiated PKC-epsilon translocation and association with RACK2.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenosine / pharmacology
  • Adenosine A1 Receptor Agonists
  • Adenosine A1 Receptor Antagonists
  • Age Factors
  • Animals
  • Antibodies / pharmacology
  • Cells, Cultured
  • Coatomer Protein / immunology
  • Coatomer Protein / metabolism*
  • Estrenes / pharmacology
  • Immunohistochemistry
  • Immunoprecipitation
  • Male
  • Membrane Proteins / immunology
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / enzymology*
  • Phosphodiesterase Inhibitors / pharmacology
  • Protein Kinase C-epsilon / metabolism*
  • Pyrrolidinones / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Adenosine A1 / metabolism
  • Type C Phospholipases / antagonists & inhibitors
  • Xanthines / pharmacology

Substances

  • Adenosine A1 Receptor Agonists
  • Adenosine A1 Receptor Antagonists
  • Antibodies
  • Coatomer Protein
  • Copb1 protein, mouse
  • Copb1 protein, rat
  • Estrenes
  • Membrane Proteins
  • Phosphodiesterase Inhibitors
  • Pyrrolidinones
  • Receptor, Adenosine A1
  • Xanthines
  • 1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
  • 2-chloro-N(6)cyclopentyladenosine
  • 1,3-dipropyl-8-cyclopentylxanthine
  • Protein Kinase C-epsilon
  • Type C Phospholipases
  • Adenosine