Enhancing calmodulin binding to cardiac ryanodine receptor completely inhibits pressure-overload induced hypertrophic signaling

AbstractCardiac hypertrophy is a well-known major risk factor for poor prognosis in patients with cardiovascular diseases. Dysregulation of intracellular Ca2+ is involved in the pathogenesis of cardiac hypertrophy. However, the precise mechanism underlying cardiac hypertrophy remains elusive. Here, we investigate whether pressure-overload induced hypertrophy can be induced by destabilization of cardiac ryanodine receptor (RyR2) through calmodulin (CaM) dissociation and subsequent Ca2+ leakage, and whether it can be genetically rescued by enhancing the binding affinity of CaM to RyR2. In the very initial phase of pressure-overload induced cardiac hypertrophy, when cardiac contractile function is preserved, reactive oxygen species (ROS)-mediated RyR2 destabilization already occurs in association with relaxation dysfunction. Further, stabilizing RyR2 by enhancing the binding affinity of CaM to RyR2 completely inhibits hypertrophic signaling and improves survival. Our study uncovers a critical missing link between RyR2 destabilization and cardiac hypertrophy.

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Contractile function in chronic gradually developing subcoronary aortic stenosis

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1981.240.1.h80 ◽

1981 ◽

Vol 240 (1) ◽

pp. H80-H84

Author(s):

B. A. Carabello ◽

R. Mee ◽

J. J. Collins ◽

R. A. Kloner ◽

D. Levin ◽

...

Keyword(s):

Aortic Stenosis ◽

Cardiac Hypertrophy ◽

Cardiac Muscle ◽

Animal Studies ◽

Contractile Function ◽

Pressure Overload ◽

Left Ventricular ◽

Stroke Work ◽

Group A ◽

Group B

Whether hypertrophied cardiac muscle functions normally or abnormally is a point of controversy in the literature. Most animal studies showing depressed performance of hypertrophied cardiac muscle have used experimental methods in which hypertrophy was produced by acutely imposing a pressure overload on the left or right ventricle, which may cause myocardial injury. To assess the possibility that chronic, slowly developing hypertrophy is associated with normal myocardial function, we developed an experimental model in which increased afterload is imposed gradually on the left ventricle in the dog. A snug band was placed around the aorta beneath the left coronary artery in puppies without producing a stenosis. As the puppies grew, relative aortic stenosis developed as increased cardiac output flowed across that fixed outflow area. One group (group A) of six puppies was banded early, whereas a second group (group B, five puppies) was banded late and served as controls. Left ventricular weight (g) to body weight (kg) ratio remained normal in group B animals (3.9 +/- 0.14), whereas this ratio was increased to 5.3 +/- 0.24 (P < 0.001) in group A animals indicating development of moderate cardiac hypertrophy. Ejection fraction, dP/dt, Vcf, and stroke work per gram of myocardium were virtually identical in both groups. We conclude that moderate, gradually developing cardiac hypertrophy as produced by this model is associated with normal myocardial contractile performance.

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The arrhythmogenic N53I variant subtly changes the structure and dynamics in the calmodulin N-terminal domain, altering its interaction with the cardiac ryanodine receptor

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.013430 ◽

2020 ◽

Vol 295 (22) ◽

pp. 7620-7634

Author(s):

Christian Holt ◽

Louise Hamborg ◽

Kelvin Lau ◽

Malene Brohus ◽

Anders Bundgaard Sørensen ◽

...

Keyword(s):

Ventricular Tachycardia ◽

Ryanodine Receptor ◽

Hydrophobic Surface ◽

Catecholaminergic Polymorphic Ventricular Tachycardia ◽

Polymorphic Ventricular Tachycardia ◽

Open Probability ◽

Calmodulin Binding ◽

Terminal Domain ◽

Genes Encoding ◽

Cardiac Ryanodine Receptor

Mutations in the genes encoding the highly conserved Ca2+-sensing protein calmodulin (CaM) cause severe cardiac arrhythmias, including catecholaminergic polymorphic ventricular tachycardia or long QT syndrome and sudden cardiac death. Most of the identified arrhythmogenic mutations reside in the C-terminal domain of CaM and mostly affect Ca2+-coordinating residues. One exception is the catecholaminergic polymorphic ventricular tachycardia–causing N53I substitution, which resides in the N-terminal domain (N-domain). It does not affect Ca2+ coordination and has only a minor impact on binding affinity toward Ca2+ and on other biophysical properties. Nevertheless, the N53I substitution dramatically affects CaM's ability to reduce the open probability of the cardiac ryanodine receptor (RyR2) while having no effect on the regulation of the plasmalemmal voltage-gated Ca2+ channel, Cav1.2. To gain more insight into the molecular disease mechanism of this mutant, we used NMR to investigate the structures and dynamics of both apo- and Ca2+-bound CaM-N53I in solution. We also solved the crystal structures of WT and N53I CaM in complex with the primary calmodulin-binding domain (CaMBD2) from RyR2 at 1.84–2.13 Å resolutions. We found that all structures of the arrhythmogenic CaM-N53I variant are highly similar to those of WT CaM. However, we noted that the N53I substitution exposes an additional hydrophobic surface and that the intramolecular dynamics of the protein are significantly altered such that they destabilize the CaM N-domain. We conclude that the N53I-induced changes alter the interaction of the CaM N-domain with RyR2 and thereby likely cause the arrhythmogenic phenotype of this mutation.

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Ryanodine Receptor Type 2 Is Required for the Development of Pressure Overload-Induced Cardiac Hypertrophy

Hypertension ◽

10.1161/hypertensionaha.111.173500 ◽

2011 ◽

Vol 58 (6) ◽

pp. 1099-1110 ◽

Cited By ~ 39

Author(s):

Yunzeng Zou ◽

Yanyan Liang ◽

Hui Gong ◽

Ning Zhou ◽

Hong Ma ◽

...

Keyword(s):

Cardiac Hypertrophy ◽

Ryanodine Receptor ◽

Pressure Overload ◽

Receptor Type

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Isolated ventricular myocytes from copper-deficient rat hearts exhibit enhanced contractile function

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.281.2.h476 ◽

2001 ◽

Vol 281 (2) ◽

pp. H476-H481 ◽

Cited By ~ 7

Author(s):

Loren E. Wold ◽

Jack T. Saari ◽

Jun Ren

Keyword(s):

Cardiac Fibrosis ◽

Copper Deficiency ◽

Ventricular Myocytes ◽

Contractile Function ◽

Detection System ◽

Cardiac Contractile Function ◽

Acetoxymethyl Ester ◽

Cardiac Contractile ◽

Rat Hearts ◽

Intracellular Ca

Dietary copper deficiency leads to cardiac hypertrophy, cardiac fibrosis, derangement of myofibrils, and impaired cardiac contractile and electrophysiological function. The purpose of this study was to determine whether impaired cardiac function from copper deficiency is due to depressed contractile function at the single myocyte level. Male Sprague-Dawley rats were fed diets that were either copper adequate (5.59–6.05 μg copper/g body wt; n = 11) or copper deficient (0.29–0.34 μg copper/g body wt; n = 11) for 5 wk. Ventricular myocytes were dispersed and mechanical properties were evaluated using the SoftEdge video-based edge-detection system. Intracellular Ca2+ transients were examined using fura 2-acetoxymethyl ester. Myocytes were electrically stimulated to contract at 0.5 Hz. Properties evaluated included peak shortening (PS), time to peak shortening (TPS), time to 90% relengthening (TR90), and maximal velocities of shortening and relengthening (±d L/d t). Myocytes from the copper-deficient rat hearts exhibited significantly enhanced PS values associated with shortened TR90 measurements compared with those from copper-adequate rat hearts. The ±d L/d t values were enhanced and the intracellular Ca2+ transient decay rate was depressed in myocytes from copper-deficient rats. These data indicate that impaired cardiac contractile function that is seen in copper-deficient whole hearts might not be due to depressed cardiac contractile function at the single cell level but rather to other mechanisms such as cardiac fibrosis.

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Redox-Active Drug, MnTE-2-PyP5+, Prevents and Treats Cardiac Arrhythmias Preserving Heart Contractile Function

Oxidative Medicine and Cellular Longevity ◽

10.1155/2020/4850697 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

Andrezza M. Barbosa ◽

José F. Sarmento-Neto ◽

José E. R. Menezes Filho ◽

Itamar C. G. Jesus ◽

Diego S. Souza ◽

...

Keyword(s):

Cardiac Arrhythmias ◽

Contractile Function ◽

Antiarrhythmic Effect ◽

Cardiac Contractile Function ◽

Rat Cardiomyocytes ◽

Cell Contractility ◽

Redox Active ◽

Intracellular Ca

Background. Cardiomyopathies remain among the leading causes of death worldwide, despite all efforts and important advances in the development of cardiovascular therapeutics, demonstrating the need for new solutions. Herein, we describe the effects of the redox-active therapeutic Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin, AEOL10113, BMX-010 (MnTE-2-PyP5+), on rat heart as an entry to new strategies to circumvent cardiomyopathies. Methods. Wistar rats weighing 250-300 g were used in both in vitro and in vivo experiments, to analyze intracellular Ca2+ dynamics, L-type Ca2+ currents, Ca2+ spark frequency, intracellular reactive oxygen species (ROS) levels, and cardiomyocyte and cardiac contractility, in control and MnTE-2-PyP5+-treated cells, hearts, or animals. Cells and hearts were treated with 20 μM MnTE-2-PyP5+ and animals with 1 mg/kg, i.p. daily. Additionally, we performed electrocardiographic and echocardiographic analysis. Results. Using isolated rat cardiomyocytes, we observed that MnTE-2-PyP5+ reduced intracellular Ca2+ transient amplitude, without altering cell contractility. Whereas MnTE-2-PyP5+ did not alter basal ROS levels, it was efficient in modulating cardiomyocyte redox state under stress conditions; MnTE-2-PyP5+ reduced Ca2+ spark frequency and increased sarcoplasmic reticulum (SR) Ca2+ load. Accordingly, analysis of isolated perfused rat hearts showed that MnTE-2-PyP5+ preserves cardiac function, increases SR Ca2+ load, and reduces arrhythmia index, indicating an antiarrhythmic effect. In vivo experiments showed that MnTE-2-PyP5+ treatment increased Ca2+ transient, preserved cardiac ejection fraction, and reduced arrhythmia index and duration. MnTE-2-PyP5+ was effective both to prevent and to treat cardiac arrhythmias. Conclusion. MnTE-2-PyP5+ prevents and treats cardiac arrhythmias in rats. In contrast to most antiarrhythmic drugs, MnTE-2-PyP5+ preserves cardiac contractile function, arising, thus, as a prospective therapeutic for improvement of cardiac arrhythmia treatment.

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Calmodulin, Which Dissociated from Cardiac Ryanodine Receptor, Plays a Pivotal Role in Driving Pathological Cardiac Hypertrophy

Journal of Cardiac Failure ◽

10.1016/j.cardfail.2017.08.190 ◽

2017 ◽

Vol 23 (10) ◽

pp. S41

Author(s):

Tetsuro Oda ◽

Takeshi Yamamoto ◽

Go Fukui ◽

Yoshihide Nakamura ◽

Shinichi Okuda ◽

...

Keyword(s):

Cardiac Hypertrophy ◽

Ryanodine Receptor ◽

Pivotal Role ◽

Pathological Cardiac Hypertrophy ◽

Cardiac Ryanodine Receptor

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Abstract 5391: Combined Ablation of Junctin and Triadin is Associated with Leaky Ryanodine Receptors and Depressed Cardiac Contractile Function

Circulation ◽

10.1161/circ.118.suppl_18.s_541-a ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Peidong Han ◽

Xiaoyang Zhou ◽

Wen Zhao ◽

Guoli Chen ◽

Shan Chen ◽

...

Keyword(s):

Ryanodine Receptor ◽

Contractile Function ◽

Ryanodine Receptors ◽

Heart Association ◽

Double Knockout ◽

Cardiac Contractile Function ◽

Protein Levels ◽

Cardiac Contractile ◽

Lower Body Weight

Junctin (JCN) and triadin (TRD) share similar structures and they both function to anchor calsequestrin (CSQ) to the ryanodine receptor (RyR) in the sarcoplasmic reticulum (SR) quaternary Ca-release complex. In failing human hearts, JCN and TRD protein levels are markedly decreased, implicating alterations in SR Ca-cycling and contractility. To address the role of combined JCN and TRD down-regulation in cardiac function, we generated and characterized a murine model deficient in both JCN and TRD. The double-knockout (DKO) mice presented lower body weight, poor fertility, and an apparent cardiac hypertrophy. In addition, deficiency of both JCN/TRD was associated with decreased peak Ca transient amplitude (34%), prolonged transient decay time (48%) and reduced caffeine-induced SR Ca-release. This depressed contractility was also confirmed at the intact organ (Langendorff perfusion) and whole animal (by echocardiography and catheterization) levels. Furthermore, examination of the properties of Ca sparks, which are informative of ryanodine receptor (RyR) gating , revealed increased frequency in the DKO myocytes, which indicated a larger opening probability of RyR. These findings suggest that the combined JCN/TRD-deficiency is associated with leaky RyR and depressed cardiac Ca-cycling, which may contribute to the progression of heart failure. This research has received full or partial funding support from the American Heart Association, AHA National Center. Table 1. Hemodynamic parameters from echocardiography and catheterization

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Mice expressing ouabain-sensitive α1-Na,K-ATPase have increased susceptibility to pressure overload-induced cardiac hypertrophy

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00625.2010 ◽

2011 ◽

Vol 300 (1) ◽

pp. H347-H355 ◽

Cited By ~ 25

Author(s):

Arshani N. Wansapura ◽

Valerie M. Lasko ◽

Jerry B Lingrel ◽

John N. Lorenz

Keyword(s):

Cardiac Hypertrophy ◽

Contractile Function ◽

Progressive Failure ◽

Pressure Overload ◽

Left Ventricular ◽

Rapid Progression ◽

Atpase Subunit ◽

Replacement Fibrosis ◽

Atpase Subunits ◽

Increased Susceptibility

The Na,K-ATPase is a ubiquitous transmembrane pump and a specific receptor for cardiac glycosides such as ouabain and digoxin, which are used in the management of congestive heart failure (CHF). A potential role for these so-called endogenous cardiotonic steroids (CS) has been explored, and it has become apparent that such compounds are elevated and may play an important role in a variety of physiological and pathophysiological conditions such as hypertension and CHF. Recent evidence suggests that the Na,K-ATPase may act as a signal transducer upon CS binding and induce nonproliferative cardiac growth, implicating a role for endogenous CS in the development of cardiac hypertrophy and progressive failure of the heart. In the present study, we tested whether hypertrophic responses to pressure overload would be altered in mutant mice that specifically express ouabain-sensitive or ouabain-resistant α1- and α2-Na,K-ATPase subunits, as follows: α1-resistant, α2-resistant (α1R/Rα2R/R); α1-sensitive, α2-resistant (α1S/Sα2R/R); and α1-resistant, α2-sensitive (α1R/Rα2S/S, wild-type). In α1S/Sα2R/R mice, pressure overload by transverse aortic coarctation induced severe left ventricular (LV) hypertrophy with extensive perivascular and replacement fibrosis at only 4 wk. Responses in α1R/Rα2S/S and α1R/Rα2R/R mice were comparatively mild. Mutant α1S/Sα2R/R mice also had LV dilatation and depressed LV systolic contractile function by 4 wk of pressure overload. In separate experiments, chronic Digibind treatment prevented the rapid progression of cardiac hypertrophy and fibrosis in α1S/Sα2R/R mice. These data demonstrate that mice with a ouabain-sensitive α1-Na,K-ATPase subunit have a dramatic susceptibility to the development of cardiac hypertrophy, and failure from LV pressure overload and provide evidence for the involvement of endogenous CS in this process.

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