TY - JOUR

T1 - Exercise Causes Arrhythmogenic Remodeling of Intracellular Calcium Dynamics in Plakophilin-2-Deficient Hearts

AU - Van Opbergen, Chantal J.M.

AU - Bagwan, Navratan

AU - Maurya, Svetlana R.

AU - Kim, Joon Chul

AU - Smith, Abigail N.

AU - Blackwell, Daniel J.

AU - Johnston, Jeffrey N.

AU - Knollmann, Björn C.

AU - Cerrone,, Marina

AU - Lundby, Alicia

AU - Delmar, Mario

N1 - Publisher Copyright: © 2022 Lippincott Williams and Wilkins. All rights reserved.

PY - 2022

Y1 - 2022

N2 - Background: Exercise training, and catecholaminergic stimulation, increase the incidence of arrhythmic events in patients affected with arrhythmogenic right ventricular cardiomyopathy correlated with plakophilin-2 (PKP2) mutations. Separate data show that reduced abundance of PKP2 leads to dysregulation of intracellular Ca2+(Ca2+i) homeostasis. Here, we study the relation between excercise, catecholaminergic stimulation, Ca2+ihomeostasis, and arrhythmogenesis in PKP2-deficient murine hearts. Methods: Experiments were performed in myocytes from a cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout murine line (PKP2cKO). For training, mice underwent 75 minutes of treadmill running once per day, 5 days each week for 6 weeks. We used multiple approaches including imaging, high-resolution mass spectrometry, electrocardiography, and pharmacological challenges to study the functional properties of cells/hearts in vitro and in vivo. Results: In myocytes from PKP2cKO animals, training increased sarcoplasmic reticulum Ca2+load, increased the frequency and amplitude of spontaneous ryanodine receptor (ryanodine receptor 2)-mediated Ca2+release events (sparks), and changed the time course of sarcomeric shortening. Phosphoproteomics analysis revealed that training led to hyperphosphorylation of phospholamban in residues 16 and 17, suggesting a catecholaminergic component. Isoproterenol-induced increase in Ca2+itransient amplitude showed a differential response to β-adrenergic blockade that depended on the purported ability of the blockers to reach intracellular receptors. Additional experiments showed significant reduction of isoproterenol-induced Ca2+isparks and ventricular arrhythmias in PKP2cKO hearts exposed to an experimental blocker of ryanodine receptor 2 channels. Conclusions: Exercise disproportionately affects Ca2+ihomeostasis in PKP2-deficient hearts in a manner facilitated by stimulation of intracellular β-adrenergic receptors and hyperphosphorylation of phospholamban. These cellular changes create a proarrhythmogenic state that can be mitigated by ryanodine receptor 2 blockade. Our data unveil an arrhythmogenic mechanism for exercise-induced or catecholaminergic life-threatening arrhythmias in the setting of PKP2 deficit. We suggest that membrane-permeable β-blockers are potentially more efficient for patients with arrhythmogenic right ventricular cardiomyopathy, highlight the potential for ryanodine receptor 2 channel blockers as treatment for the control of heart rhythm in the population at risk, and propose that PKP2-dependent and phospholamban-dependent arrhythmogenic right ventricular cardiomyopathy-related arrhythmias have a common mechanism.

AB - Background: Exercise training, and catecholaminergic stimulation, increase the incidence of arrhythmic events in patients affected with arrhythmogenic right ventricular cardiomyopathy correlated with plakophilin-2 (PKP2) mutations. Separate data show that reduced abundance of PKP2 leads to dysregulation of intracellular Ca2+(Ca2+i) homeostasis. Here, we study the relation between excercise, catecholaminergic stimulation, Ca2+ihomeostasis, and arrhythmogenesis in PKP2-deficient murine hearts. Methods: Experiments were performed in myocytes from a cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout murine line (PKP2cKO). For training, mice underwent 75 minutes of treadmill running once per day, 5 days each week for 6 weeks. We used multiple approaches including imaging, high-resolution mass spectrometry, electrocardiography, and pharmacological challenges to study the functional properties of cells/hearts in vitro and in vivo. Results: In myocytes from PKP2cKO animals, training increased sarcoplasmic reticulum Ca2+load, increased the frequency and amplitude of spontaneous ryanodine receptor (ryanodine receptor 2)-mediated Ca2+release events (sparks), and changed the time course of sarcomeric shortening. Phosphoproteomics analysis revealed that training led to hyperphosphorylation of phospholamban in residues 16 and 17, suggesting a catecholaminergic component. Isoproterenol-induced increase in Ca2+itransient amplitude showed a differential response to β-adrenergic blockade that depended on the purported ability of the blockers to reach intracellular receptors. Additional experiments showed significant reduction of isoproterenol-induced Ca2+isparks and ventricular arrhythmias in PKP2cKO hearts exposed to an experimental blocker of ryanodine receptor 2 channels. Conclusions: Exercise disproportionately affects Ca2+ihomeostasis in PKP2-deficient hearts in a manner facilitated by stimulation of intracellular β-adrenergic receptors and hyperphosphorylation of phospholamban. These cellular changes create a proarrhythmogenic state that can be mitigated by ryanodine receptor 2 blockade. Our data unveil an arrhythmogenic mechanism for exercise-induced or catecholaminergic life-threatening arrhythmias in the setting of PKP2 deficit. We suggest that membrane-permeable β-blockers are potentially more efficient for patients with arrhythmogenic right ventricular cardiomyopathy, highlight the potential for ryanodine receptor 2 channel blockers as treatment for the control of heart rhythm in the population at risk, and propose that PKP2-dependent and phospholamban-dependent arrhythmogenic right ventricular cardiomyopathy-related arrhythmias have a common mechanism.

KW - arrhythmogenic right ventricular cardiomyopathy

KW - exercise

KW - phospholamban

KW - plakophilins

KW - receptors, adrenergic, beta-1

UR - http://www.scopus.com/inward/record.url?scp=85129998646&partnerID=8YFLogxK

U2 - 10.1161/CIRCULATIONAHA.121.057757

DO - 10.1161/CIRCULATIONAHA.121.057757

M3 - Journal article

C2 - 35491884

AN - SCOPUS:85129998646

VL - 145

SP - 1480

EP - 1496

JO - Circulation

JF - Circulation

SN - 0009-7322

IS - 19

ER -