title: Effects of protein kinase a on the phosphorylation status and transverse stiffness of cardiac myofibrils.
abstract: Stimulation of β-adrenergic receptors in cardiac myocytes activates cyclic AMP-dependent protein kinase A (PKA). PKA-mediated phosphorylation of myofibrils decreases their longitudinal stiffness, but its effect on transverse stiffness is not fully understood. We thus examined the effects of PKA treatment on the transverse stiffness of cardiac myofibrils by atomic force microscopy and determined the phosphorylation levels of myofibril components by SDS-PAGE. Transverse stiffness was significantly decreased by PKA treatment concomitantly with increased phosphorylation of troponin I, myosin-binding protein C, and titin (also called connectin). Subsequent treatment with protein phosphatase 1 abrogated these PKA-mediated effects.
authors.affiliation: Department of Physiology, Tsurumi University School of Dental Medicine, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Ohnuki
authors.forename: Takenori
authors.initials: T
authors.lastname: Yamada
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Mototani
authors.forename: Daisuke
authors.initials: D
authors.lastname: Umeki
authors.forename: Kouichi
authors.initials: K
authors.lastname: Shiozawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Fujita
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Saeki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Okumura
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D064211:Connectin / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology* / Q000502:physiology; D004548:Elasticity / Q000187:drug effects*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D018625:Microscopy, Atomic Force; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000502:physiology* / Q000648:ultrastructure; D009210:Myofibrils / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D010766:Phosphorylation; D054645:Protein Phosphatase 1 / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta; D019210:Troponin I / Q000378:metabolism; D000099163:Myosin Binding Protein C
chemical_list: D002352:Carrier Proteins; D064211:Connectin; D017868:Cyclic AMP-Dependent Protein Kinases; D054645:Protein Phosphatase 1; D011943:Receptors, Adrenergic, beta; D019210:Troponin I; D000099163:Myosin Binding Protein C