β-Adrenoceptor stimulation potentiates insulin-stimulated PKB phosphorylation in rat cardiomyocytes via cAMP and PKA

Jorid T. Stuenæs, Yu Chiang Lai, Astrid Bolling, Ada Ingvaldsen, Camilla Rommundstad, Emina Sudar, Fang Chin Lin, Jørgen Jensen

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Background and purpose: Genetic approaches have documented protein kinase B (PKB) as a pivotal regulator of heart function. Insulin strongly activates PKB, whereas adrenaline is not considered a major physiological regulator of PKB in heart. In skeletal muscles, however, adrenaline potentiates insulin-stimulated PKB activation without having effect in the absence of insulin. The purpose of the present study was to investigate the interaction between insulin and β-adrenergic stimulation in regulation of PKB phosphorylation. Experimental approach: Cardiomyocytes were isolated from adult rats by collagenase, and incubated with insulin, isoprenaline, and other compounds. Protein phosphorylation was evaluated by Western blot and phospho-specific antibodies. Key results: Isoprenaline increased insulin-stimulated PKB Ser 473 and Thr 308 phosphorylation more than threefold in cardiomyocytes. Isoprenaline alone did not increase PKB phosphorylation. Isoprenaline also increased insulin-stimulated GSK-3β Ser 9 phosphorylation approximately twofold, supporting that PKB phosphorylation increased kinase activity. Dobutamine (β 1-agonist) increased insulin-stimulated PKB phosphorylation as effectively as isoprenaline (more than threefold), whereas salbutamol (β 2-agonist) only potentiated insulin-stimulated PKB phosphorylation by approximately 80%. Dobutamine, but not salbutamol, increased phospholamban Ser 16 phosphorylation and glycogen phosphorylase activation (PKA-mediated effects). Furthermore, the cAMP analogue that activates PKA (dibutyryl-cAMP and N 6-benzoyl-cAMP) increased insulin-stimulated PKB phosphorylation by more than threefold without effect alone. The Epac-specific activator 8-(4-chlorophenylthio)-2′-O- methyl-cAMP (007) increased insulin-stimulated PKB phosphorylation by approximately 50%. Db-cAMP and N 6-benzoyl-cAMP, but not 007, increased phospholamban Ser 16 phosphorylation. Conclusions and implications: β-adrenoceptors are strong regulators of PKB phosphorylation via cAMP and PKA when insulin is present. We hypothesize that PKB mediates important signalling in the heart during β-adrenergic receptors stimulation.

Original languageEnglish
Pages (from-to)116-129
Number of pages14
JournalBritish Journal of Pharmacology
Volume160
Issue number1
Early online date23 Mar 2010
DOIs
Publication statusPublished - 1 May 2010

Keywords

  • Akt
  • ERK
  • GSK-3
  • Heart
  • Hypertrophy
  • Phoshodiesterase
  • Phosphatidylinositol 3-kinase
  • Phospholamban
  • Phosphorylation
  • Rolipram

ASJC Scopus subject areas

  • Pharmacology

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