title: Myofibril growth during cardiac hypertrophy is regulated through dual phosphorylation and acetylation of the actin capping protein CapZ.
abstract: The mechanotransduction signaling pathways initiated in heart muscle by increased mechanical loading are known to lead to long-term transcriptional changes and hypertrophy, but the rapid events for adaptation at the sarcomeric level are not fully understood. The goal of this study was to test the hypothesis that actin filament assembly during cardiomyocyte growth is regulated by post-translational modifications (PTMs) of CapZβ1. In rapidly hypertrophying neonatal rat ventricular myocytes (NRVMs) stimulated by phenylephrine (PE), two-dimensional gel electrophoresis (2DGE) of CapZβ1 revealed a shift toward more negative charge. Consistent with this, mass spectrometry identified CapZβ1 phosphorylation on serine-204 and acetylation on lysine-199, two residues which are near the actin binding surface of CapZβ1. Ectopic expression of dominant negative PKCɛ (dnPKCɛ) in NRVMs blunted the PE-induced increase in CapZ dynamics, as evidenced by the kinetic constant (Kfrap) of fluorescence recovery after photobleaching (FRAP), and concomitantly reduced phosphorylation and acetylation of CapZβ1. Furthermore, inhibition of class I histone deacetylases (HDACs) increased lysine-199 acetylation on CapZβ1, which increased Kfrap of CapZ and stimulated actin dynamics. Finally, we show that PE treatment of NRVMs results in decreased binding of HDAC3 to myofibrils, suggesting a signal-dependent mechanism for the regulation of sarcomere-associated CapZβ1 acetylation. Taken together, this dual regulation through phosphorylation and acetylation of CapZβ1 provides a novel model for the regulation of myofibril growth during cardiac hypertrophy.
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612-7342, United States; Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612-7342, United States.
authors.forename: Ying-Hsi
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612-7342, United States; Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612-7342, United States.
authors.forename: Chad M
authors.initials: CM
authors.lastname: Warren
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612-7342, United States; Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612-7342, United States.
authors.forename: Jieli
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Medicine, Division of Cardiology and Center for Fibrosis Research and Translation, University of Colorado Anschutz Medical Campus, Aurora, CO 80045-0508, United States.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: McKinsey
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612-7342, United States; Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612-7342, United States. Electronic address: russell@uic.edu.
authors.forename: Brenda
authors.initials: B
authors.lastname: Russell
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D051347:CapZ Actin Capping Protein / Q000737:chemistry / Q000378:metabolism*; D006332:Cardiomegaly / Q000378:metabolism* / Q000473:pathology; D048429:Cell Size / Q000187:drug effects; D006352:Heart Ventricles / Q000473:pathology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006655:Histone Deacetylases / Q000378:metabolism; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D009210:Myofibrils / Q000187:drug effects / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D051744:Protein Kinase C-epsilon / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017207:Rats, Sprague-Dawley; D012518:Sarcomeres / Q000187:drug effects / Q000378:metabolism; D000099186:Histone Deacetylase 3
chemical_list: D000199:Actins; D051347:CapZ Actin Capping Protein; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases; D010656:Phenylephrine; D051744:Protein Kinase C-epsilon; D000099186:Histone Deacetylase 3
keywords: Actin assembly; Mechanotransduction; Proteomics; Sarcomere; Signaling pathways