title: Dynamic protein kinase a activities induced by beta-adrenoceptors dictate signaling propagation for substrate phosphorylation and myocyte contraction.
abstract: cAMP/protein kinase (PK)A activation represents a key signaling mechanism for neurohormonal stimulation of diversified physiological processes. Using real-time, fluorescence resonance energy transfer-based imaging of PKA activity in neonatal cardiac myocytes, we report that sustained activation of PKA induced by beta-adrenoceptor (betaAR) dictates signaling propagation for substrate phosphorylation and myocyte contraction. Activation of betaARs in wild-type myocytes induces strong and sustained PKA activities, which are rapidly attenuated on washing away agonist or adding antagonist to the cells. The sustained PKA activities promote signaling propagation to the sarcoplasmic reticulum for phosphorylation of phospholamban and increases in myocyte contraction. Addition of antagonist after betaAR stimulation significantly attenuates PKA phosphorylation of phospholamban and rapidly reduces contraction rate increases. Moreover, stimulation of beta(1)AR subtype induces PKA activities similar to those in wild-type cells. In contrast, stimulation of beta(2)AR subtype induces strong initial activation of PKA similar to those induced by beta(1)AR; however, the activities are rapidly decreased to baseline levels. The transient PKA activities are sufficient for phosphorylation of the overexpressed beta(2)ARs under agonist stimulation, but not phospholamban. Further analysis reveals that phosphodiesterase 4 is the major family that shapes PKA activities under betaAR stimulation. Inhibition of phosphodiesterase 4 extends beta(2)AR-induced PKA activities, promotes PKA phosphorylation of phospholamban, and ultimately enhances myocyte contraction responses. Together, our data have revealed insights into kinetics of PKA activities in signaling propagation under neurohormonal stimulation.
authors.affiliation: Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, 407 S Goodwin Ave, Urbana, IL 61801, USA.
authors.forename: Dagoberto
authors.initials: D
authors.lastname: Soto
authors.forename: Vania
authors.initials: V
authors.lastname: De Arcangelis
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Xiang
mesh_terms: D018674:Adrenergic Antagonists / Q000494:pharmacology; D058671:Adrenergic beta-1 Receptor Antagonists; D058672:Adrenergic beta-2 Receptor Antagonists; D000818:Animals; D000831:Animals, Newborn; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D018342:Receptors, Adrenergic, beta-1 / Q000235:genetics / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D000099211:Phospholamban
chemical_list: D018674:Adrenergic Antagonists; D058671:Adrenergic beta-1 Receptor Antagonists; D058672:Adrenergic beta-2 Receptor Antagonists; D002135:Calcium-Binding Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D000099211:Phospholamban