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van der Heide MYC, Verstraelen TE, van Lint FHM, Bosman LP, de Brouwer R, Proost VM, van Drie E, Taha K, Zwinderman AH, Dickhoff C, Schoonderwoerd BA, Germans T, Houweling AC, Gimeno-Blanes JR, van der Zwaag PA, de Boer RA, Cox MGPJ, van Tintelen JP, Wilde AAM. Long-term reliability of the phospholamban (PLN) p.(Arg14del) risk model in predicting major ventricular arrhythmia: a landmark study. Europace 2024; 26:euae069. [PMID: 38558121 PMCID: PMC10983074 DOI: 10.1093/europace/euae069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024] Open
Abstract
AIMS Recently, a genetic variant-specific prediction model for phospholamban (PLN) p.(Arg14del)-positive individuals was developed to predict individual major ventricular arrhythmia (VA) risk to support decision-making for primary prevention implantable cardioverter defibrillator (ICD) implantation. This model predicts major VA risk from baseline data, but iterative evaluation of major VA risk may be warranted considering that the risk factors for major VA are progressive. Our aim is to evaluate the diagnostic performance of the PLN p.(Arg14del) risk model at 3-year follow-up. METHODS AND RESULTS We performed a landmark analysis 3 years after presentation and selected only patients with no prior major VA. Data were collected of 268 PLN p.(Arg14del)-positive subjects, aged 43.5 ± 16.3 years, 38.9% male. After the 3 years landmark, subjects had a mean follow-up of 4.0 years (± 3.5 years) and 28 (10%) subjects experienced major VA with an annual event rate of 2.6% [95% confidence interval (CI) 1.6-3.6], defined as sustained VA, appropriate ICD intervention, or (aborted) sudden cardiac death. The PLN p.(Arg14del) risk score yielded good discrimination in the 3 years landmark cohort with a C-statistic of 0.83 (95% CI 0.79-0.87) and calibration slope of 0.97. CONCLUSION The PLN p.(Arg14del) risk model has sustained good model performance up to 3 years follow-up in PLN p.(Arg14del)-positive subjects with no history of major VA. It may therefore be used to support decision-making for primary prevention ICD implantation not merely at presentation but also up to at least 3 years of follow-up.
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Affiliation(s)
- Myrthe Y C van der Heide
- Department of Cardiology, Heart Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Tom E Verstraelen
- Department of Cardiology, Heart Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Freyja H M van Lint
- Department of Human Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
| | - Laurens P Bosman
- Division Heart and Lungs, Department of Cardiology, University Medical Center Utrecht, University of Utrecht, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
| | - Remco de Brouwer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, Netherlands
| | - Virginnio M Proost
- Department of Cardiology, Heart Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Esmée van Drie
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
| | - Karim Taha
- Division Heart and Lungs, Department of Cardiology, University Medical Center Utrecht, University of Utrecht, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
| | - Aeilko H Zwinderman
- Department of Clinical Epidemiology and Biostatistics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Cathelijne Dickhoff
- Department of Cardiology, Dijklander Ziekenhuis Hoorn, Maelsonstraat 3, 1624 NP Hoorn, Netherlands
| | - Bas A Schoonderwoerd
- Department of Cardiology, Medical Center Leeuwarden, Henri Dunantweg 2, 8934 AD Leeuwarden, Netherlands
| | - Tjeerd Germans
- Department of Cardiology, Noordwest Ziekenhuisgroep, Wilhelminalaan 12, 1815 JD Alkmaar, Netherlands
| | - Arjan C Houweling
- Department of Human Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Juan R Gimeno-Blanes
- Department of Cardiology, Virgen de Arrixaca Hospital, Ctra, Murcia-Cartagena, s/n, El Palmar, 30120 Murcia, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARDHEART)
| | - Paul A van der Zwaag
- Department of Clinical Genetics, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, Netherlands
| | - Rudolf A de Boer
- Department of Cardiology, Erasmus Medical Center, University of Erasmus Rotterdam, Doctor Molewaterplein 40, 3015 GD Rotterdam, Netherlands
| | - Moniek G P J Cox
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, Netherlands
| | - J Peter van Tintelen
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARDHEART)
| | - Arthur A M Wilde
- Department of Cardiology, Heart Center, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARDHEART)
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2
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Zeppenfeld K, Kimura Y, Ebert M. Mapping and Ablation of Ventricular Tachycardia in Inherited Left Ventricular Cardiomyopathies. JACC Clin Electrophysiol 2023:S2405-500X(23)00816-2. [PMID: 38127011 DOI: 10.1016/j.jacep.2023.10.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/12/2023] [Accepted: 10/23/2023] [Indexed: 12/23/2023]
Abstract
Advances in the field of human genetics have led to an accumulating understanding of the genetic basis of distinct nonischemic cardiomyopathies associated with ventricular tachycardias (VTs) and sudden cardiac death. To date, there is an increasing proportion of patients with inherited cardiomyopathies requiring catheter ablation for VTs. This review provides an overview of disease-causing gene mutations frequently encountered and relevant for clinical electrophysiologists. Available data on VT ablation in patients with an inherited etiology and a phenotype of a nondilated left ventricular cardiomyopathy, dilated cardiomyopathy, or hypertrophic cardiomyopathy are summarized. VTs amenable to catheter ablation are related to nonischemic fibrosis. Recent insights into genotype-phenotype relations of subtype and location of fibrosis have important implications for treatment planning. Current strategies to delineate nonischemic fibrosis and related arrhythmogenic substrates using multimodal imaging, image integration, and electroanatomical mapping are provided. The ablation approach depends on substrate location and extension. Related procedural aspects including patient-tailored (enhanced) ablation strategies and outcomes are outlined. Challenging substrates for VT and the underlying inherited etiologies with a high risk for rapid progressive heart failure contribute to poor outcomes after catheter ablation. Electroanatomical data obtained during ablation may allow the identification of patients at particular risk who need to be considered for early work-up for left ventricular assist device implantation or heart transplantation.
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Affiliation(s)
- Katja Zeppenfeld
- Department of Cardiology, Heart-Lung-Center, Leiden University Medical Center, Leiden, the Netherlands; Willem Einthoven Center of Arrhythmia Research and Management, Leiden, the Netherlands, and Aarhus, Denmark.
| | - Yoshitaka Kimura
- Department of Cardiology, Heart-Lung-Center, Leiden University Medical Center, Leiden, the Netherlands; Willem Einthoven Center of Arrhythmia Research and Management, Leiden, the Netherlands, and Aarhus, Denmark
| | - Micaela Ebert
- Department of Cardiology, Heart-Lung-Center, Leiden University Medical Center, Leiden, the Netherlands; Division of Electrophysiology, Department of Internal Medicine and Cardiology, Heart Center Dresden, Technische Universität Dresden, Dresden, Germany
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3
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Naito S, Higo S, Kameda S, Ogawa S, Tabata T, Akazawa Y, Nakamura D, Nakamoto K, Sera F, Kuramoto Y, Asano Y, Hikoso S, Miyagawa S, Sakata Y. End-stage Hypertrophic Cardiomyopathy with Advanced Heart Failure in Patients Carrying MYH7 R453 Variants: A Case Series. Intern Med 2023; 62:3167-3173. [PMID: 36948619 PMCID: PMC10686745 DOI: 10.2169/internalmedicine.1497-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/12/2023] [Indexed: 03/24/2023] Open
Abstract
The MYH7 R453 variant has been identified in inherited hypertrophic cardiomyopathy (HCM) and is associated with sudden death and a poor prognosis. The detailed clinical course of HCM with the MYH7 R453 variant, from a preserved to a reduced left ventricular ejection fraction, has not been reported. We identified the MYH7 R453C and R453H variants in three patients who progressively developed advanced heart failure requiring circulatory support and summarized the clinical course and echocardiographic parameters of these patients over the years. Because of the rapid disease progression, we consider genetic screening for patients with HCM imperative for future prognosis stratification.
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Affiliation(s)
| | - Shuichiro Higo
- Department of Medical Therapeutics for Heart Failure, Osaka University Graduate School of Medicine, Japan
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Satoshi Kameda
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Shou Ogawa
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Tomoka Tabata
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Yasuhiro Akazawa
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Daisuke Nakamura
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Kei Nakamoto
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Fusako Sera
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Yuki Kuramoto
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Yoshihiro Asano
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
- Clinical Genetic Counseling Room, National Cerebral and Cardiovascular Center, Japan
| | - Shungo Hikoso
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
| | - Shigeru Miyagawa
- Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, Japan
| | - Yasushi Sakata
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Japan
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Vafiadaki E, Glijnis PC, Doevendans PA, Kranias EG, Sanoudou D. Phospholamban R14del disease: The past, the present and the future. Front Cardiovasc Med 2023; 10:1162205. [PMID: 37144056 PMCID: PMC10151546 DOI: 10.3389/fcvm.2023.1162205] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/03/2023] [Indexed: 05/06/2023] Open
Abstract
Arrhythmogenic cardiomyopathy affects significant number of patients worldwide and is characterized by life-threatening ventricular arrhythmias and sudden cardiac death. Mutations in multiple genes with diverse functions have been reported to date including phospholamban (PLN), a key regulator of sarcoplasmic reticulum (SR) Ca2+ homeostasis and cardiac contractility. The PLN-R14del variant in specific is recognized as the cause in an increasing number of patients worldwide, and extensive investigations have enabled rapid advances towards the delineation of PLN-R14del disease pathogenesis and discovery of an effective treatment. We provide a critical overview of current knowledge on PLN-R14del disease pathophysiology, including clinical, animal model, cellular and biochemical studies, as well as diverse therapeutic approaches that are being pursued. The milestones achieved in <20 years, since the discovery of the PLN R14del mutation (2006), serve as a paradigm of international scientific collaboration and patient involvement towards finding a cure.
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Affiliation(s)
- Elizabeth Vafiadaki
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- Correspondence: Elizabeth Vafiadaki Despina Sanoudou
| | - Pieter C. Glijnis
- Stichting Genetische Hartspierziekte PLN, Phospholamban Foundation, Wieringerwerf, Netherlands
| | - Pieter A. Doevendans
- Netherlands Heart Institute, Utrecht, Netherlands
- Department of Cardiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Evangelia G. Kranias
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Despina Sanoudou
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- Clinical Genomics and Pharmacogenomics Unit, 4th Department of Internal Medicine, Attikon Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Center for New Biotechnologies and Precision Medicine, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Correspondence: Elizabeth Vafiadaki Despina Sanoudou
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5
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Rogalska ME, Vafiadaki E, Erpapazoglou Z, Haghighi K, Green L, Mantzoros CS, Hajjar RJ, Tranter M, Karakikes I, Kranias EG, Stillitano F, Kafasla P, Sanoudou D. Isoform changes of action potential regulators in the ventricles of arrhythmogenic phospholamban-R14del humanized mouse hearts. Metabolism 2023; 138:155344. [PMID: 36375644 DOI: 10.1016/j.metabol.2022.155344] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/30/2022] [Accepted: 11/01/2022] [Indexed: 11/13/2022]
Abstract
Arrhythmogenic cardiomyopathy (ACM) is characterized by life-threatening ventricular arrhythmias and sudden cardiac death and affects hundreds of thousands of patients worldwide. The deletion of Arginine 14 (p.R14del) in the phospholamban (PLN) gene has been implicated in the pathogenesis of ACM. PLN is a key regulator of sarcoplasmic reticulum (SR) Ca2+ cycling and cardiac contractility. Despite global gene and protein expression studies, the molecular mechanisms of PLN-R14del ACM pathogenesis remain unclear. Using a humanized PLN-R14del mouse model and human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs), we investigated the transcriptome-wide mRNA splicing changes associated with the R14del mutation. We identified >200 significant alternative splicing (AS) events and distinct AS profiles were observed in the right (RV) and left (LV) ventricles in PLN-R14del compared to WT mouse hearts. Enrichment analysis of the AS events showed that the most affected biological process was associated with "cardiac cell action potential", specifically in the RV. We found that splicing of 2 key genes, Trpm4 and Camk2d, which encode proteins regulating calcium homeostasis in the heart, were altered in PLN-R14del mouse hearts and human iPSC-CMs. Bioinformatical analysis pointed to the tissue-specific splicing factors Srrm4 and Nova1 as likely upstream regulators of the observed splicing changes in the PLN-R14del cardiomyocytes. Our findings suggest that aberrant splicing may affect Ca2+-homeostasis in the heart, contributing to the increased risk of arrythmogenesis in PLN-R14del ACM.
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Affiliation(s)
- Malgorzata E Rogalska
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona 08003, Spain
| | - Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece
| | - Zoi Erpapazoglou
- Institute for Fundamental Biomedical Research, B.S.R.C. "Alexander Fleming", 16672 Athens, Greece
| | - Kobra Haghighi
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Lisa Green
- Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Christos S Mantzoros
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Section of Endocrinology, Boston VA Healthcare System, Harvard Medical School, Boston, MA 02215, USA
| | | | - Michael Tranter
- Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Ioannis Karakikes
- Department of Cardiothoracic Surgery and Cardiovascular Institute, Stanford University School of Medicine, 240 Pasteur Dr, Stanford, CA 94304, USA
| | - Evangelia G Kranias
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Francesca Stillitano
- Division Heart and Lung, Department of Cardiology, University Medical Center Utrecht, 3584, CX, Utrecht, the Netherlands
| | - Panagiota Kafasla
- Institute for Fundamental Biomedical Research, B.S.R.C. "Alexander Fleming", 16672 Athens, Greece
| | - Despina Sanoudou
- Molecular Biology Division, Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece; Clinical Genomics and Pharmacogenomics Unit, 4(th) Department of Internal Medicine, Attikon Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; Center for New Biotechnologies and Precision Medicine, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece.
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6
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Tabata T, Masumura Y, Higo S, Kunimatsu S, Kameda S, Inoue H, Okuno S, Ogawa S, Takashima S, Watanabe M, Miyagawa S, Hikoso S, Sakata Y. Multiplexed measurement of cell type-specific calcium kinetics using high-content image analysis combined with targeted gene disruption. Biochem Biophys Res Commun 2022; 637:40-49. [PMID: 36375249 DOI: 10.1016/j.bbrc.2022.10.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
Abstract
Kinetic analysis of intracellular calcium (Ca2+) in cardiomyocytes is commonly used to determine the pathogenicity of genetic mutations identified in patients with dilated cardiomyopathy (DCM). Conventional methods for measuring Ca2+ kinetics target whole-well cultured cardiomyocytes and therefore lack information concerning individual cells. Results are also affected by heterogeneity in cell populations. Here, we developed an analytical method using CRISPR/Cas9 genome editing combined with high-content image analysis (HCIA) that links cell-by-cell Ca2+ kinetics and immunofluorescence images in thousands of cardiomyocytes at a time. After transfecting cultured mouse cardiomyocytes that constitutively express Cas9 with gRNAs, we detected a prolonged action potential duration specifically in Serca2a-depleted ventricular cardiomyocytes in mixed culture. To determine the phenotypic effect of a frameshift mutation in PKD1 in a patient with DCM, we introduced the mutation into Cas9-expressing cardiomyocytes by gRNA transfection and found that it decreases the expression of PKD1-encoded PC1 protein that co-localizes specifically with Serca2a and L-type voltage-gated calcium channels. We also detected the suppression of Ca2+ amplitude in ventricular cardiomyocytes with decreased PC1 expression in mixed culture. Our HCIA method provides comprehensive kinetic and static information on individual cardiomyocytes and allows the pathogenicity of mutations to be determined rapidly.
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Affiliation(s)
- Tomoka Tabata
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Yuki Masumura
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Shuichiro Higo
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan; Department of Medical Therapeutics for Heart Failure, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan.
| | - Suzuka Kunimatsu
- Department of Clinical Laboratory and Biomedical Sciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Satoshi Kameda
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Hiroyuki Inoue
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Shota Okuno
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Shou Ogawa
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Seiji Takashima
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Mikio Watanabe
- Department of Clinical Laboratory and Biomedical Sciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Shigeru Miyagawa
- Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Shungo Hikoso
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Yasushi Sakata
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
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Aberrant PLN-R14del Protein Interactions Intensify SERCA2a Inhibition, Driving Impaired Ca2+ Handling and Arrhythmogenesis. Int J Mol Sci 2022; 23:ijms23136947. [PMID: 35805951 PMCID: PMC9266971 DOI: 10.3390/ijms23136947] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/20/2022] [Accepted: 06/20/2022] [Indexed: 02/01/2023] Open
Abstract
Phospholamban (PLN), a key modulator of Ca2+-homeostasis, inhibits sarcoplasmic reticulum (SR) calcium-ATPase (SERCA2a) and regulates cardiac contractility. The human PLN mutation R14del has been identified in arrhythmogenic cardiomyopathy patients worldwide and is currently extensively investigated. In search of the molecular mechanisms mediating the pathological phenotype, we examined PLN-R14del associations to known PLN-interacting partners. We determined that PLN-R14del interactions to key Ca2+-handling proteins SERCA2a and HS-1-associated protein X-1 (HAX-1) were enhanced, indicating the super-inhibition of SERCA2a’s Ca2+-affinity. Additionally, histidine-rich calcium binding protein (HRC) binding to SERCA2a was increased, suggesting the inhibition of SERCA2a maximal velocity. As phosphorylation relieves the inhibitory effect of PLN on SERCA2a activity, we examined the impact of phosphorylation on the PLN-R14del/SERCA2a interaction. Contrary to PLN-WT, phosphorylation did not affect PLN-R14del binding to SERCA2a, due to a lack of Ser-16 phosphorylation in PLN-R14del. No changes were observed in the subcellular distribution of PLN-R14del or its co-localization to SERCA2a. However, in silico predictions suggest structural perturbations in PLN-R14del that could impact its binding and function. Our findings reveal for the first time that by increased binding to SERCA2a and HAX-1, PLN-R14del acts as an enhanced inhibitor of SERCA2a, causing a cascade of molecular events contributing to impaired Ca2+-homeostasis and arrhythmogenesis. Relieving SERCA2a super-inhibition could offer a promising therapeutic approach for PLN-R14del patients.
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