scholarly journals Post-Translational Modifications and Diastolic Calcium Leak Associated to the Novel RyR2-D3638A Mutation Lead to CPVT in Patient-Specific hiPSC-Derived Cardiomyocytes

2018 ◽  
Vol 7 (11) ◽  
pp. 423 ◽  
Author(s):  
Ivana Acimovic ◽  
Marwan Refaat ◽  
Adrien Moreau ◽  
Anton Salykin ◽  
Steve Reiken ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Sarcoplasmic Reticulum ◽  
Molecular Mechanisms ◽  
Disease Modeling ◽  
Exercise Stress ◽  
Polymorphic Ventricular Tachycardia ◽  
Patient Specific ◽  
Inadequate Response ◽  
Post Translational Modifications ◽  
Electrophysiological Properties

Background: Sarcoplasmic reticulum Ca2+ leak and post-translational modifications under stress have been implicated in catecholaminergic polymorphic ventricular tachycardia (CPVT), a highly lethal inherited arrhythmogenic disorder. Human induced pluripotent stem cells (hiPSCs) offer a unique opportunity for disease modeling. Objective: The aims were to obtain functional hiPSC-derived cardiomyocytes from a CPVT patient harboring a novel ryanodine receptor (RyR2) mutation and model the syndrome, drug responses and investigate the molecular mechanisms associated to the CPVT syndrome. Methods: Patient-specific cardiomyocytes were generated from a young athletic female diagnosed with CPVT. The contractile, intracellular Ca2+ handling and electrophysiological properties as well as the RyR2 macromolecular remodeling were studied. Results: Exercise stress electrocardiography revealed polymorphic ventricular tachycardia when treated with metoprolol and marked improvement with flecainide alone. We found abnormal stress-induced contractile and electrophysiological properties associated with sarcoplasmic reticulum Ca2+ leak in CPVT hiPSC-derived cardiomyocytes. We found inadequate response to metoprolol and a potent response of flecainide. Stabilizing RyR2 with a Rycal compound prevents those abnormalities specifically in CPVT hiPSC-derived cardiomyocytes. The RyR2-D3638A mutation is located in the conformational change inducing-central core domain and leads to RyR2 macromolecular remodeling including depletion of PP2A and Calstabin2. Conclusion: We identified a novel RyR2-D3638A mutation causing 3D conformational defects and aberrant biophysical properties associated to RyR2 macromolecular complex post-translational remodeling. The molecular remodeling is for the first time revealed using patient-specific hiPSC-derived cardiomyocytes which may explain the CPVT proband’s resistance. Our study promotes hiPSC-derived cardiomyocytes as a suitable model for disease modeling, testing new therapeutic compounds, personalized medicine and deciphering underlying molecular mechanisms.

scholarly journals Mutation-specific differences in arrhythmias and drug responses in CPVT patients: simultaneous patch clamp and video imaging of iPSC derived cardiomyocytes

2019 ◽  
Vol 47 (2) ◽  
pp. 1067-1077 ◽  
Author(s):  
R. P. Pölönen ◽  
H. Swan ◽  
K. Aalto-Setälä
Keyword(s):  
Disease Modeling ◽  
Induced Pluripotent Stem Cell ◽  
Polymorphic Ventricular Tachycardia ◽  
Patient Specific ◽  
Electrophysiological Properties ◽  
Electrophysiological Measurements ◽  
Skin Biopsies ◽  
Induced Pluripotent ◽  
Almost All ◽  
And Control

AbstractCatecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease characterized by arrhythmias under adrenergic stress. Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for CPVT. We characterized electrophysiological properties of CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) carrying different mutations in RYR2 and evaluated effects of carvedilol and flecainide on action potential (AP) and contractile properties of hiPSC-CMs. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion (E3D) and L4115F mutation in RYR2. APs and contractile movement were recorded simultaneously from the same hiPSC-CMs. Differences in AP properties of ventricular like CMs were seen in CPVT and control CMs: APD90 of both E3D (n = 20) and L4115F (n = 25) CPVT CMs was shorter than in control CMs (n = 15). E3D-CPVT CMs had shortest AP duration, lowest AP amplitude, upstroke velocity and more depolarized diastolic potential than controls. Adrenaline had positive and carvedilol and flecainide negative chronotropic effect in all hiPSC CMs. CPVT CMs had increased amount of delayed after depolarizations (DADs) and early after depolarizations (EADs) after adrenaline exposure. E3D CPVT CMs had the most DADs, EADs, and tachyarrhythmia. Discordant negatively coupled alternans was seen in L4115F CPVT CMs. Carvedilol cured almost all arrhythmias in L4115F CPVT CMs. Both drugs decreased contraction amplitude in all hiPSC CMs. E3D CPVT CMs have electrophysiological properties, which render them more prone to arrhythmias. iPSC-CMs provide a unique platform for disease modeling and drug screening for CPVT. Combining electrophysiological measurements, we can gain deeper insight into mechanisms of arrhythmias.

scholarly journals A Homozygous CASQ2 Mutation in a Japanese Patient with Catecholaminergic Polymorphic Ventricular Tachycardia

2019 ◽  
Vol 2019 ◽  
pp. 1-3
Author(s):  
Taishi Fujisawa ◽  
Yoshiyasu Aizawa ◽  
Yoshinori Katsumata ◽  
Akihiro Udo ◽  
Shogo Ito ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Japanese Patient ◽  
Stress Testing ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Exercise Stress ◽  
Polymorphic Ventricular Tachycardia ◽  
Ventricular Ectopy ◽  
Recessive Form ◽  
History Of ◽  
Structural Disease

A 62-year-old female had suffered from recurrent syncopal episodes triggered by physical and emotional stress since childhood. She had no family history of sudden death. An intensive examination could not detect any structural disease, and exercise stress testing provoked polymorphic ventricular ectopy followed by polymorphic ventricular tachycardia accompanied with syncope leading to a diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT). A genetic analysis with a next generation sequencer identified a homozygous W361X mutation in the CASQ2 gene. Careful history taking disclosed that her parents had a consanguineous marriage. Here we present a Japanese patient with a recessive form of CPVT.

scholarly journals Disease Modeling of Mitochondrial Cardiomyopathy Using Patient-Specific Induced Pluripotent Stem Cells

Biology ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 981
Author(s):  
Takeshi Tokuyama ◽  
Razan Elfadil Ahmed ◽  
Nawin Chanthra ◽  
Tatsuya Anzai ◽  
Hideki Uosaki
Keyword(s):  
Pluripotent Stem Cells ◽  
Genetic Variants ◽  
Molecular Mechanisms ◽  
Disease Modeling ◽  
Induced Pluripotent Stem Cell ◽  
Drug Efficacy ◽  
Patient Specific ◽  
Experimental Platform ◽  
Mitochondrial Cardiomyopathy ◽  
Induced Pluripotent

Mitochondrial cardiomyopathy (MCM) is characterized as an oxidative phosphorylation disorder of the heart. More than 100 genetic variants in nuclear or mitochondrial DNA have been associated with MCM. However, the underlying molecular mechanisms linking genetic variants to MCM are not fully understood due to the lack of appropriate cellular and animal models. Patient-specific induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) provide an attractive experimental platform for modeling cardiovascular diseases and predicting drug efficacy to such diseases. Here we introduce the pathological and therapeutic studies of MCM using iPSC-CMs and discuss the questions and latest strategies for research using iPSC-CMs.

scholarly journals Human RyR2 (Ryanodine Receptor 2) Loss-of-Function Mutations

2021 ◽  
Vol 14 (9) ◽  
Author(s):  
Yanhui Li ◽  
Jinhong Wei ◽  
Wenting Guo ◽  
Bo Sun ◽  
John Paul Estillore ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Sudden Cardiac Death ◽  
Cardiac Death ◽  
Stress Testing ◽  
Functional Characterization ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Exercise Stress ◽  
Polymorphic Ventricular Tachycardia ◽  
Loss Of Function

Background: The overall objective of the present study is to extend our understanding of the clinical phenotype and underlying mechanism of a newly discovered cardiac arrhythmia syndrome through a multicenter study. Gain-of-function mutations in the cardiac Ca 2+ release channel (RyR2 [ryanodine receptor 2]) cause catecholaminergic polymorphic ventricular tachycardia, whereas loss-of-function RyR2 mutations are linked to a new cardiac arrhythmia disorder termed Ca 2+ -release deficiency syndrome (CRDS). Catecholaminergic polymorphic ventricular tachycardia is an inherited arrhythmia disorder characterized by stress-induced bidirectional and polymorphic ventricular tachyarrhythmias and is routinely diagnosed by using exercise stress testing. Conversely, RyR2-CRDS is characterized by ventricular arrhythmias and sudden cardiac death but a negative exercise stress testing for catecholaminergic polymorphic ventricular tachycardia. There are currently no clinical diagnostic tests for CRDS and affected patients may manifest with sudden cardiac death as their first symptom. In the absence of effective clinical diagnostic tools, in vitro functional characterization of associated RyR2 mutations provides an alternative means to identify potential cases of CRDS. Methods: We searched for patients presenting with phenotypes compatible with CRDS that have RyR2 mutations and performed in vitro functional characterization. Results: We found that 3 novel (G570D, R4147K, and A4203V) and 2 previously reported (M4109R and A4204V) RyR2 mutations associated with CRDS phenotypes markedly reduced caffeine-induced Ca 2+ release and store overload-induced Ca 2+ release. We also characterized 2 additional loss-of-function RyR2 mutations previously reported (Q3925E and L4769S) that are located in the central and channel pore-forming domains critical for Ca 2+ activation and channel gating. Q3925E was identified through postmortem genetic testing in an individual who died suddenly, while L4769S is a variant of uncertain significance reported in ClinVar, suggesting that RyR2 CRDS may be under detected. Conclusions: These findings provide further support for the existence of an emerging RyR2 loss-of-function associated arrhythmia syndrome (CRDS) and shed new insights into the disease mechanism.

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.

Monogenic and oligogenic cardiovascular diseases: genetics of arrhythmias—catecholaminergic polymorphic ventricular tachycardia

ESC CardioMed ◽  
2018 ◽  
pp. 683-685
Author(s):  
Peter J. Schwartz ◽  
Lia Crotti
Keyword(s):  
Ventricular Tachycardia ◽  
Beta Blockers ◽  
Stress Test ◽  
Exercise Stress Test ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Exercise Stress ◽  
Polymorphic Ventricular Tachycardia ◽  
Cascade Screening ◽  
Icd Implantation ◽  
Symptomatic Diagnosis

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited disorder associated with syncope and sudden death manifesting in the young during sympathetic activation. The electrocardiogram is normal and the heart is structurally normal. The diagnosis is usually made with an exercise stress test that shows a typical pattern of onset and offset of adrenergically induced ventricular arrhythmias. Molecular screening of RyR2, the major CPVT gene, is recommended whenever the suspicion of CPVT is high. If a disease-causing mutation is identified, cascade screening allows pre-symptomatic diagnosis among family members. All affected subjects should be treated with beta blockers (nadolol or propranolol). Preliminary data support the association of beta blockers with flecainide. After a cardiac arrest, an implantable cardioverter defibrillator (ICD) should be implanted, but it is accompanied by a disquietingly high incidence of adverse effects. After syncope on beta blocker therapy, left cardiac sympathetic denervation is most effective, preserves quality of life, and does not preclude a subsequent ICD implantation.

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