Crucial Role for Ca 2+ /Calmodulin-Dependent Protein Kinase-II in Regulating Diastolic Stress of Normal and Failing Hearts via Titin Phosphorylation
Open Access
- 15 February 2013
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Circulation Research
- Vol. 112 (4), 664-674
- https://doi.org/10.1161/circresaha.111.300105
Abstract
Rationale: Myocardial diastolic stiffness and cardiomyocyte passive force (Fpassive) depend in part on titin isoform composition and phosphorylation. Ca2+/calmodulin-dependent protein kinase-II (CaMKII) phosphorylates ion channels, Ca2+-handling proteins, and chromatin-modifying enzymes in the heart, but has not been known to target titin. Objective: To elucidate whether CaMKII phosphorylates titin and modulates Fpassive in normal and failing myocardium. Methods and Results: Titin phosphorylation was assessed in CaMKIIδ/γ double-knockout (DKO) mouse, transgenic CaMKIIδC-overexpressing mouse, and human hearts, by Pro-Q-Diamond/Sypro-Ruby staining, autoradiography, and immunoblotting using phosphoserine-specific titin-antibodies. CaMKII-dependent site-specific titin phosphorylation was quantified in vivo by mass spectrometry using stable isotope labeling by amino acids in cell culture mouse heart mixed with wild-type (WT) or DKO heart. Fpassive of single permeabilized cardiomyocytes was recorded before and after CaMKII-administration. All-titin phosphorylation was reduced by >50% in DKO but increased by up to ≈100% in transgenic versus WT hearts. Conserved CaMKII-dependent phosphosites were identified within the PEVK-domain of titin by quantitative mass spectrometry and confirmed in recombinant human PEVK-fragments. CaMKII also phosphorylated the cardiac titin N2B-unique sequence. Phosphorylation at specific PEVK/titin N2B-unique sequence sites was decreased in DKO and amplified in transgenic versus WT hearts. Fpassive was elevated in DKO and reduced in transgenic compared with WT cardiomyocytes. CaMKII-administration lowered Fpassive of WT and DKO cardiomyocytes, an effect blunted by titin antibody pretreatment. Human end-stage failing hearts revealed higher CaMKII expression/activity and phosphorylation at PEVK/titin N2B-unique sequence sites than nonfailing donor hearts. Conclusions: CaMKII phosphorylates the titin springs at conserved serines/threonines, thereby lowering Fpassive. Deranged CaMKII-dependent titin phosphorylation occurs in heart failure and contributes to altered diastolic stress.Keywords
This publication has 57 references indexed in Scilit:
- On Marathons and Sprints: An Integrated Quantitative Proteomics and Transcriptomics Analysis of Differences Between Slow and Fast Muscle FibersMolecular & Cellular Proteomics, 2012
- Quantitative maps of protein phosphorylation sites across 14 different rat organs and tissuesNature Communications, 2012
- CaMKII in myocardial hypertrophy and heart failureJournal of Molecular and Cellular Cardiology, 2011
- GPS 2.1: enhanced prediction of kinase-specific phosphorylation sites with an algorithm of motif length selection"Protein Engineering, Design and Selection", 2010
- Synergy between CaMKII Substrates and β-Adrenergic Signaling in Regulation of Cardiac Myocyte Ca2+ HandlingBiophysical Journal, 2010
- The γ isoform of CaM kinase II controls mouse egg activation by regulating cell cycle resumptionProceedings of the National Academy of Sciences of the United States of America, 2009
- The cAMP binding protein Epac regulates cardiac myofilament functionProceedings of the National Academy of Sciences of the United States of America, 2009
- Modulation of Titin-Based Stiffness by Disulfide Bonding in the Cardiac Titin N2-B Unique SequenceBiophysical Journal, 2009
- The δ isoform of CaM kinase II is required for pathological cardiac hypertrophy and remodeling after pressure overloadProceedings of the National Academy of Sciences of the United States of America, 2009
- Interactions of multiple signaling pathways in neuropeptide Y-mediated bimodal vascular smooth muscle cell growthCanadian Journal of Physiology and Pharmacology, 2008