scholarly journals A Novel Mice Model of Catecholaminergic Polymorphic Ventricular Tachycardia Generated by CRISPR/Cas9

2021 ◽  
Author(s):  
cuilan hou ◽  
Xunwei jiang ◽  
Qingzhu Qiu ◽  
Junmin Zheng ◽  
Shujia Lin ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Induced Pluripotent Stem Cell ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Calcium Handling ◽  
Polymorphic Ventricular Tachycardia ◽  
Mice Model ◽  
Isolated Cardiomyocytes ◽  
Therapeutic Targeting ◽  
Protein Levels ◽  
Induced Pluripotent

Catecholaminergic polymorphic ventricular tachycardia (CPVT) has been considered as one of the most important causes of children's sudden cardiac death. Mutations in the genes for RyR2 and CASQ2, two mainly subtypes of CPVT, have been identified. However, the mutation in the gene of TECRL was rarely reported, which could be another genetic cause of CPVT. We evaluated myocardial contractility, electrophysiology, calcium handling in Tecrl knockout (Tecrl KO) mice and human induced pluripotent stem cell-derived cardiomyocytes. Immediately after epinephrine plus caffeine injection, Tecrl KO mice showed much more multiple premature ventricular beats and ventricular tachycardia. The Tecrl KO mice demonstrate CPVT phenotypes. Mechanistically, intracellular calcium amplitude was reduced, while time to baseline of 50 was increased in acute isolated cardiomyocytes. RyR2 protein levels decreased significantly upon cycloheximide treatment in TECRL deficiency cardiomyocytes. Overexpression of TECRL and KN93 can partially reverse cardiomyocytes calcium dysfunction, and this is p-CaMKII/CaMKII dependent. Therefore, a new CPVT mouse model was constructed. We propose a previously unrecognized mechanism of TECRL and provide support for the therapeutic targeting of TECRL in treating CPVT

scholarly journals Antiarrhythmic Effects of Carvedilol and Flecainide in Cardiomyocytes Derived from Catecholaminergic Polymorphic Ventricular Tachycardia Patients

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
R. P. Pölönen ◽  
K. Penttinen ◽  
H. Swan ◽  
K. Aalto-Setälä
Keyword(s):  
Ventricular Tachycardia ◽  
Drug Effects ◽  
Induced Pluripotent Stem Cell ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Polymorphic Ventricular Tachycardia ◽  
Patient Specific ◽  
Best Response ◽  
Intracellular Ca ◽  
Beating Rate ◽  
Induced Pluripotent

Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for catecholaminergic polymorphic ventricular tachycardia (CPVT). In this study, we evaluated antiarrhythmic efficacy of carvedilol and flecainide in CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) carrying different mutations in RYR2. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion and L4115 or V4653F mutation in RYR2 and of a healthy individual. Ca2+ kinetics and drug effects were studied with Fluo-4 AM indicator. Carvedilol abolished Ca2+ abnormalities in 31% of L4115F, 36% of V4653F, and 46% of exon 3 deletion carrying CPVT cardiomyocytes and flecainide 33%, 30%, and 52%, respectively. Both drugs lowered the intracellular Ca2+ level and beating rate of the cardiomyocytes significantly. Moreover, flecainide caused abnormal Ca2+ transients in 61% of controls compared to 26% of those with carvedilol. Carvedilol and flecainide were equally effective in CPVT iPSC-CMs. However, flecainide induced arrhythmias in 61% of control cells. CPVT cardiomyocytes carrying the exon 3 deletion had the most severe Ca2+ abnormalities, but they had the best response to drug therapies. According to this study, the arrhythmia-abolishing effect of neither of the drugs is optimal. iPSC-CMs provide a unique platform for testing drugs for CPVT.

Abstract 15566: Induced Pluripotent Stem Cell-Derived Cardiomyocytes Recapitulate Clinically Observed Refractoriness to Therapeutic β-Blockade in a Patient-Specific Model of Catecholaminergic Polymorphic Ventricular Tachycardia

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Marcela K Preininger ◽  
Rajneesh Jha ◽  
Qingling Wu ◽  
Monalisa Singh ◽  
Joshua T Maxwell ◽  
...  
Keyword(s):  
Stem Cell ◽  
Ventricular Tachycardia ◽  
Pluripotent Stem Cell ◽  
Induced Pluripotent Stem Cell ◽  
Polymorphic Ventricular Tachycardia ◽  
Patient Specific ◽  
Blocker Therapy ◽  
Β Blocker ◽  
Induced Pluripotent

Introduction: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome characterized by diastolic store overload-induced Ca2+ waves during β-adrenergic receptor (β-AR) stimulation. Mysteriously, β-blockers are ineffective at abolishing stress-induced ventricular arrhythmias in ~25% of patients. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from these CPVT patients offer an attractive system for investigating the phenomenon, but it remains unknown whether iPSC-CMs can recapitulate clinically observed patient-specific drug responses. Hypothesis: This study assessed the hypothesis that patient-specific refractoriness to β-blocker therapy can be observed in vitro using CPVT iPSC-CMs. Methods: We generated iPSC-CMs from a control individual and a CPVT patient insensitive to the widely prescribed β-blocker nadolol, but responsive to flecainide, and compared the efficacy of the two drugs in vitro in diminishing diastolic Ca2+ waves and restoring Ca2+ spark parameters during β-AR stimulation. Results: In CPVT hiPSC-CMs (n = 34), β-AR agonism elicited intense diastolic Ca2+ waves and potentiated unduly frequent, large, and prolonged Ca2+ sparks compared to control iPSC-CMs (n = 12). Pursuant to the patient’s in vivo responses, nadolol-treated CPVT iPSC-CMs (n = 27) demonstrated inadequate improvement of Ca2+ handling defects during β-AR stimulation relative to flecainide-treated CPVT iPSC-CMs (n = 25). Nadolol showed no significant effect on the frequency of diastolic Ca2+ waves, but reduced mean amplitude by 50% (p < 0.0001). In contrast, flecainide reduced both frequency and amplitude by 83% (p < 0.001) and 72% (p < 0.0001), respectively. During nadolol treatment, Ca2+ spark frequency, width, and duration remained significantly altered, while flecainide restored all Ca2+ spark parameters to baseline levels. Conclusions: Clinically observed recalcitrance to β-blocker therapy in individuals with CPVT can be modeled in vitro using patient-derived iPSC-CMs. Furthermore, the efficacy of other drugs such as flecainide can be comparatively evaluated, supporting the use of patient-specific iPSC-CMs as a clinically-relevant implement of precision medicine.

Unfolded Protein Response and Triad Formation in Skeletal Muscles of Catecholaminergic Polymorphic Ventricular Tachycardia Mouse / Odgovor Razvijenog Proteina I Formiranje Trijada U Skeletnim Mišićima Miševa Sa Kateholaminergičkom Polimorfnom Ventrikularnom Tahikardijom

2014 ◽  
Vol 31 (4) ◽  
pp. 225-231
Author(s):  
Rigers Bakiu
Keyword(s):  
Ventricular Tachycardia ◽  
Unfolded Protein Response ◽  
Calcium Binding ◽  
Skeletal Muscles ◽  
Point Mutations ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Polymorphic Ventricular Tachycardia ◽  
Protein Levels ◽  
Unfolded Protein ◽  
Protein Response

Summary Isoform 2 of calsequestrin (CASQ2) is the main calcium-binding protein of sarcoplasmic reticulum (SR), expressed both in cardiac and in skeletal muscles. CASQ2 acts as an SR calcium (Ca2+) sensor and regulates SR Ca2+ release via interactions with triadin, junctin, and the ryanodine receptor. Various mutations of the csq2 gene lead to altered Ca2+ release and contractile dysfunction contributing to the development of arrhythmias and sudden cardiac death in young individuals affected by catecholaminergic polymorphic ventricular tachycardia (CPVT). Recently, a transgenic mouse carrying one of the identified CASQ2 point-mutations (R33Q) associated to CPVT was developed and a drastic reduction of the mutated protein was observed. Following a biomolecular approach, several analysis were performed using different antibody treatments in order to identify when the reduction of CASQ2 begins in skeletal muscles, unveil the mechanism involved in the reduction of CASQ2 in slow-twitch and fast twitch muscles and verify if other proteins are affected by the presence of the mutated protein. Mutated CASQ2 decreased soon after birth. Up-regulation of proteins associated to the unfolded protein response (UPR) was also observed. Important proteins in skeletal muscle triads formation were analyzed and increased protein levels were observed in adult knock-in CASQ2-R33Q/R33Q mice. Probably, R33Q mutation induced the decrease of CASQ2 by activation of the UPR and subsequently degradation through proteasome.

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