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Groeneweg JA, van der Zwaag PA, Jongbloed JDH, Cox MGPJ, Vreeker A, de Boer RA, van der Heijden JF, van Veen TAB, McKenna WJ, van Tintelen JP, Dooijes D, Hauer RNW. Left-dominant arrhythmogenic cardiomyopathy in a large family: associated desmosomal or nondesmosomal genotype? Heart Rhythm 2012; 10:548-59. [PMID: 23270881 DOI: 10.1016/j.hrthm.2012.12.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Arrhythmogenic cardiomyopathy (AC) is considered a predominantly right ventricular (RV) desmosomal disease. However, left-dominant forms due to desmosomal gene mutations, including PKP2 variant c.419C>T, have been described. Recently, a nondesmosomal phospholamban (PLN) mutation (c.40_42delAGA) has been identified, causing dilated cardiomyopathy and arrhythmias. OBJECTIVE To gain more insight into pathogenicity of the PKP2 variant c.419C>T by cosegregation analysis of the PKP2 variant c.419C>T vs the PLN mutation c.40_42delAGA. METHODS A Dutch family (13 family members, median age 49 years, range 34-71 years) with ventricular tachycardia underwent (1) meticulous phenotypic characterization and (2) screening of 5 desmosomal genes (PKP2, DSC2, DSG2, DSP, JUP) and PLN. RESULTS Six family members fulfilled 2010 AC Task Force Criteria. Seven had signs of left ventricular (LV) involvement (inverted T waves in leads V4-V6, LV wall motion abnormalities and late enhancement, and reduced LV ejection fraction), including 6 family members with proven AC. The PKP2 variant c.419C>T was found as a single variant in 3 family members, combined with the PLN mutation c.40_42delAGA in 3 others. PLN mutation was found in 9 family members, including the 6 with AC and all 7 with LV involvement. The PLN mutation c.40_42delAGA was found as a single mutation in 6, combined with the PKP2 variant c.419C>T in 3 others. A low-voltage electrocardiogram was seen in 4 of 9 PLN mutation-positive subjects. None of the family members with the single PKP2 variant showed any sign of RV or LV involvement. CONCLUSIONS The PLN mutation c.40_42delAGA cosegregates with AC and with electrocardiographic and structural LV abnormalities. In this family, there was no evidence of disease-causing contribution of the PKP2 variant c.419C>T.
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Affiliation(s)
- Judith A Groeneweg
- Department of Cardiology, University Medical Center Utrecht and Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands.
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202
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Rasmussen TB, Hansen J, Nissen PH, Palmfeldt J, Dalager S, Jensen UB, Kim WY, Heickendorff L, Mølgaard H, Jensen HK, Sørensen KE, Baandrup UT, Bross P, Mogensen J. Protein expression studies of desmoplakin mutations in cardiomyopathy patients reveal different molecular disease mechanisms. Clin Genet 2012; 84:20-30. [PMID: 23137101 DOI: 10.1111/cge.12056] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 11/06/2012] [Accepted: 06/11/2012] [Indexed: 11/29/2022]
Abstract
Mutations in the gene for desmoplakin (DSP) may cause arrhythmogenic right ventricular cardiomyopathy (ARVC) and Carvajal syndrome (CS). Desmoplakin is part of all desmosomes, which are abundantly expressed in both myocardial and epidermal tissue and serve as intercellular mechanical junctions. This study aimed to investigate protein expression in myocardial and epidermal tissue of ARVC and CS patients carrying DSP mutations in order to elucidate potential molecular disease mechanisms. Genetic investigations identified three ARVC patients carrying different heterozygous DSP mutations in addition to a homozygous DSP mutation in a CS patient. The protein expression of DSP in mutation carriers was evaluated in biopsies from myocardial and epidermal tissue by immunohistochemistry. Keratinocyte cultures were established from skin biopsies of mutation carriers and characterized by reverse transcriptase polymerase chain reaction, western blotting, and protein mass spectrometry. The results showed that the mutation carriers had abnormal DSP expression in both myocardial and epidermal tissue. The investigations revealed that the disease mechanisms varied accordingly to the specific types of DSP mutation identified and included haploinsufficiency, dominant-negative effects, or a combination hereof. Furthermore, the results suggest that the keratinocytes cultured from patients are a valuable and easily accessible resource to elucidate the effects of desmosomal gene mutations in humans.
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Affiliation(s)
- T B Rasmussen
- Department of Cardiology; Research Unit for Molecular Medicine, Odense University Hospital, Sdr. Boulevard 29, Odense C, Denmark
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203
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Lombardi R, Marian AJ. Arrhythmogenic right ventricular cardiomyopathy is a disease of cardiac stem cells. Curr Opin Cardiol 2012; 25:222-8. [PMID: 20124997 DOI: 10.1097/hco.0b013e3283376daf] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE To review recent developments in clinical aspects, molecular genetics and pathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC). RECENT FINDINGS ARVC is a primary disease of the myocardium characterized by fibro-adipocytic replacement of myocytes, predominantly in the right ventricle. Phenotypic expression of ARVC is variable and a significant number of patients may exhibit a subtle phenotype, particularly in the early stages of the disease. Mutations in DSP, JUP, PKP2, DSG2 and DSC2, encoding desmosomal proteins desmoplakin, plakoglobin, plakophilin 2 (PKP2), desmoglein 2 (DSG2), and desmocollin 2 (DSC2), respectively, cause ARVC. Thus, ARVC, at least in a subset, is a disease of desmosomes. In addition, mutations in TMEM43 and TGFB1 have been associated with ARVC. Mechanistic studies indicate that suppressed canonical Wnt signaling, imposed by nuclear plakoglobin, is the responsible mechanism for the pathogenesis of ARVC. It leads to the differentiation of a subset of second heart field cardiac progenitor cells at the epicardium to adipocytes due to enhanced expression of adipogenic factors. This mechanism explains the predominant involvement of the right ventricle in ARVC. Hence, ARVC is the first identified disease of disrupted differentiation of cardiac progenitor cells. SUMMARY Advances in molecular genetics and the pathogenesis of ARVC could afford the opportunity for a genetic-based diagnosis and development of novel diagnostic markers and therapeutic targets aimed to prevent, attenuate and reverse the evolving phenotype.
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Affiliation(s)
- Raffaella Lombardi
- Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston, Houston, Texas 77030, USA
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204
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Arrhythmogenic right ventricular cardiomyopathy: Reassessing the link with the desmosome. Pathology 2012; 44:596-604. [DOI: 10.1097/pat.0b013e32835a0163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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205
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Swope D, Li J, Radice GL. Beyond cell adhesion: the role of armadillo proteins in the heart. Cell Signal 2012; 25:93-100. [PMID: 23022961 DOI: 10.1016/j.cellsig.2012.09.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
Plakoglobin (PG, γ-Catenin, JUP), a member of the armadillo protein family and close homolog of β-catenin, functions to link cell surface cadherin molecules with the cytoskeleton. PG is the only junctional component found in both desmosomes and adherens junctions and thus plays a critical role in the regulation of cell-cell adhesion. Similar to β-catenin, PG is able to interact with components of the Wnt signaling pathway and directly affect gene expression by binding with LEF/TCF transcription factors. In addition, it has been proposed that PG functions primarily as a competitive inhibitor of β-catenin transcriptional activity by sequestering LEF/TCF. Compared to β-catenin, the contribution of PG as a transcriptional regulator in either physiological or pathological conditions is poorly understood. There is increasing clinical interest in PG as both a structural protein as well as a signaling molecule as mutations have been identified in the human PG gene that cause Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) and cutaneous syndromes. This review will discuss the connection between altered cell adhesion and gene expression and its contribution to disease pathogenesis.
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Affiliation(s)
- David Swope
- Center for Translational Medicine, Department of Medicine, Jefferson Medical College, Philadelphia, PA 19107, USA
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206
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Basso C, Corrado D, Bauce B, Thiene G. Arrhythmogenic right ventricular cardiomyopathy. Circ Arrhythm Electrophysiol 2012; 5:1233-46. [PMID: 23022706 DOI: 10.1161/circep.111.962035] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Cristina Basso
- Department of Cardiac, Thoracic, and Vascular Sciences, University of Padua Medical School, Padua, Italy.
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207
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Paul M, Wichter T, Fabritz L, Waltenberger J, Schulze-Bahr E, Kirchhof P. Arrhythmogenic right ventricular cardiomyopathy: an update on pathophysiology, genetics, diagnosis, and risk stratification. Herzschrittmacherther Elektrophysiol 2012; 23:186-95. [PMID: 23011601 DOI: 10.1007/s00399-012-0233-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 07/20/2012] [Indexed: 12/17/2022]
Abstract
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy accounting for life-threatening ventricular tachyarrhythmias and sudden death in young individuals and athletes. Over the past years, mutations in desmosomal genes have been identified as disease-causative. However, genetic heterogeneity and variable phenotypic expression alongside with diverse disease progression still render the evaluation of its prognostic implication difficult. ARVC was initially entered into the canon of cardiomyopathies of the World Health Organization in 1995, and international efforts have resulted in the 2010 modified diagnostic criteria for ARVC. Despite all additional insights into pathophysiology, clinical management, and modern risk stratification, under-/misdiagnosing of ARVC remains a problem and hampers reliable statements on the incidence, prevalence, and natural course of the disease.This review provides a comprehensive overview of the current literature on the pathogenesis, diagnosis, treatment, and prognosis of ARVC and sheds some light on potential new developments in these areas.
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Affiliation(s)
- M Paul
- Division of Cardiology, Department of Cardiovascular Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1 (Gebäude A1), 48149, Münster, Germany.
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208
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Hauer RNW, Cox MGPJ, Groeneweg JA. Impact of new electrocardiographic criteria in arrhythmogenic cardiomyopathy. Front Physiol 2012; 3:352. [PMID: 23015790 PMCID: PMC3449333 DOI: 10.3389/fphys.2012.00352] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 08/16/2012] [Indexed: 01/13/2023] Open
Abstract
Arrhythmogenic cardiomyopathy (AC) has originally been described as a disorder characterized by fibrofatty replacement of the myocardium, primarily of the right ventricle (RV), and ventricular tachyarrhythmias, sudden death, and at a late stage progressive heart failure. Arrhythmogenic right ventricular dysplasia or cardiomyopathy (ARVD/C) was the previous name of the disease. However, similar histopathologic changes are also found in the left ventricle (LV). AC is also considered a hereditary disease. Recent molecular genetic studies provide accumulating evidence that fibrofatty replacement is preceded by mutation-related desmosomal changes. Desmosomal dysfunction may lead to mechanical and thereafter electrical uncoupling, ultimately resulting in conduction delay. This activation delay and conduction block, provide a substrate for re-entrant mechanisms and thereby ventricular tachycardia (VT). The gold standard for AC diagnosis is demonstration of transmural fibrofatty replacement in cardiac tissue obtained by autopsy or surgery. To facilitate diagnosis in clinical practice, an international Task Force defined in 1994 a set of criteria (TFC) based on electrocardiographic, functional and morphologic features, and family history. These criteria have recently been revised. Routine 12-lead electrocardiography is one of the most important tools for AC diagnosis in all stages of the disease. Even in the absence of other markers in the early concealed stage of the disease, in line with early slow conduction and electrical uncoupling ECG analysis may contribute to early diagnosis. Activation delay and site of origin of VT are reflected in various characteristics of the surface 12-lead electrocardiogram. Since the ECG is easy to obtain, this technique is particularly useful, for both diagnosis and follow up of disease progression.
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Affiliation(s)
- Richard N W Hauer
- Department of Cardiology, University Medical Center Utrecht Utrecht, Netherlands ; Interuniversity Cardiology Institute of the Netherlands Utrecht, Netherlands
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209
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Thiene G, Rigato I, Pilichou K, Corrado D, Basso C. Arrhythmogenic right ventricular cardiomyopathy. Herz 2012; 37:657-62. [DOI: 10.1007/s00059-012-3678-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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210
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Fabritz L, Fortmüller L, Yu TY, Paul M, Kirchhof P. Can preload-reducing therapy prevent disease progression in arrhythmogenic right ventricular cardiomyopathy? Experimental evidence and concept for a clinical trial. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:340-6. [PMID: 22944071 DOI: 10.1016/j.pbiomolbio.2012.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 08/09/2012] [Indexed: 12/28/2022]
Abstract
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy and a leading cause of sudden cardiac death in a young population. ARVC is especially common in young athletes. Mutations in different desmosomal genes have been identified causing dysfunctional cell-cell contacts. Reduced myocardial expression of plakoglobin in cell-cell contact complexes appears to associate with disease manifestation in patients harbouring mutations within other cell-cell contact genes. Experimental data suggest that preload reduction may be a simple and effective intervention to prevent disease progression and ventricular arrhythmias in ARVC. This review discusses the potential effects of this innovative approach and describes the design of the first controlled trial of preload-reducing therapy in patients with ARVC.
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Affiliation(s)
- Larissa Fabritz
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, United Kingdom.
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212
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Marcus FI, Abidov A. Arrhythmogenic right ventricular cardiomyopathy 2012: diagnostic challenges and treatment. J Cardiovasc Electrophysiol 2012; 23:1149-53. [PMID: 22909229 DOI: 10.1111/j.1540-8167.2012.02412.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The most common presentation of arrhythmogenic right ventricular cardiomyopathy (ARVC) is palpitations or ventricular tachycardia (VT) of left bundle branch morphology in a young or middle-aged individual. The 12-lead electrocardiogram may be normal or have T-wave inversion beyond V(1) in an otherwise healthy person who is suspected of having ARVC. The most frequent imaging abnormalities are an enlarged right ventricle, decrease in right ventricular (RV) function, and localized wall motion abnormalities. Risk factors for implantable cardioverter defibrillator include a history of aborted sudden death, syncope, young age, decreased left ventricular function, and marked decrease in RV function. Recent results of treatment with epicardial ablation are encouraging.
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Affiliation(s)
- Frank I Marcus
- Section of Cardiology, Department of Medicine, University of Arizona College of Medicine, Tucson, Arizona, USA.
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213
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Roberts SEA, Pryce JW, Weber MA, Malone M, Ashworth MT, Sebire NJ. Clinicopathological features of fatal cardiomyopathy in childhood: an autopsy series. J Paediatr Child Health 2012; 48:675-80. [PMID: 22515160 DOI: 10.1111/j.1440-1754.2012.02450.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM Cardiomyopathy, a group of primary myocardial disorders, is an uncommon, but important, cause of death in childhood. This study examines the demographic, clinical and pathological features of fatal cardiomyopathy in childhood with particular reference to its classification and autopsy findings. METHOD The method of this study was a retrospective structured review of all paediatric autopsies performed at a single specialist centre from 1995 to 2009 inclusive, in order to determine the demographic, clinical and pathological features of fatal cardiomyopathy. RESULTS From a total of 2229 autopsies performed at the centre during the study period on live-born infants and children, 34 confirmed cases of cardiomyopathy were identified (1.5%). More than half (59%) of these cases occurred in infants (less than 1 year of age). Heart weight of cardiomyopathy cases was significantly greater than those with normal hearts (P < 0.001), and 77% had heart weights above the 95th percentile of the normal expected range for age, including all of those over 1 year age. Of cardiomyopathy cases, 50% were primary dilated cardiomyopathy and 27% were primary hypertrophic cardiomyopathy. Twelve of 34 cases (35%) presented as sudden unexpected death, the diagnosis of cardiomyopathy being only made at autopsy. CONCLUSION Cardiomyopathy is an uncommon cause of death in infancy and childhood. It can present as sudden unexpected death and encompasses a range of aetiologies. Heart weight above the 95th percentile at autopsy is present in most cases but heart weight may be within the normal range in infants.
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Affiliation(s)
- Sebastian E A Roberts
- UCL Institute of Child Health, Department of Paediatric Pathology, Great Ormond Street Hospital for Children, University College London, United Kingdom
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214
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Pilichou K, Thiene G, Basso C. Assessing the Significance of Pathogenic Mutations and Autopsy Findings in the Light of 2010 Arrhythmogenic Right Ventricular Cardiomyopathy Diagnostic Criteria. ACTA ACUST UNITED AC 2012; 5:384-6. [DOI: 10.1161/circgenetics.112.964163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Kalliopi Pilichou
- From the Department of Cardiac, Thoracic, and Vascular Sciences, Cardiovascular Pathology, University of Padua, Padua, Italy
| | - Gaetano Thiene
- From the Department of Cardiac, Thoracic, and Vascular Sciences, Cardiovascular Pathology, University of Padua, Padua, Italy
| | - Cristina Basso
- From the Department of Cardiac, Thoracic, and Vascular Sciences, Cardiovascular Pathology, University of Padua, Padua, Italy
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215
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van der Zwaag PA, van Rijsingen IAW, Asimaki A, Jongbloed JDH, van Veldhuisen DJ, Wiesfeld ACP, Cox MGPJ, van Lochem LT, de Boer RA, Hofstra RMW, Christiaans I, van Spaendonck-Zwarts KY, Lekanne dit Deprez RH, Judge DP, Calkins H, Suurmeijer AJH, Hauer RNW, Saffitz JE, Wilde AAM, van den Berg MP, van Tintelen JP. Phospholamban R14del mutation in patients diagnosed with dilated cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy: evidence supporting the concept of arrhythmogenic cardiomyopathy. Eur J Heart Fail 2012; 14:1199-207. [PMID: 22820313 DOI: 10.1093/eurjhf/hfs119] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AIMS To investigate whether phospholamban gene (PLN) mutations underlie patients diagnosed with either arrhythmogenic right ventricular cardiomyopathy (ARVC) or idiopathic dilated cardiomyopathy (DCM). METHODS AND RESULTS We screened a cohort of 97 ARVC and 257 DCM unrelated index patients for PLN mutations and evaluated their clinical characteristics. PLN mutation R14del was identified in 12 (12 %) ARVC patients and in 39 (15 %) DCM patients. Haplotype analysis revealed a common founder, estimated to be between 575 and 825 years old. A low voltage electrocardiogram was present in 46 % of R14del carriers. Compared with R14del- DCM patients, R14del+ DCM patients more often demonstrated appropriate implantable cardioverter defibrillator discharge (47 % vs. 10 % , P < 0.001), cardiac transplantation (18 % vs. 2 % , P < 0.001), and a family history for sudden cardiac death (SCD) at < 50 years (36 % vs. 16 % , P = 0.007). We observed a similar pattern in the ARVC patients although this was not statistically significant. The average age of 26 family members who died of SCD was 37.7 years. Immunohistochemistry in available myocardial samples revealed absent/depressed plakoglobin levels at intercalated disks in five of seven (71 %) R14del+ ARVC samples, but in only one of nine (11 %) R14del+ DCM samples (P = 0.03). CONCLUSIONS The PLN R14del founder mutation is present in a substantial number of patients clinically diagnosed with DCM or ARVC. R14del+ patients diagnosed with DCM showed an arrhythmogenic phenotype, and SCD at young age can be the presenting symptom. These findings support the concept of 'arrhythmogenic cardiomyopathy'.
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Affiliation(s)
- Paul A van der Zwaag
- Department of Genetics, University of Groningen, University Medical Center Groningen, The Netherlands
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216
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Ma D, Wei H, Lu J, Ho S, Zhang G, Sun X, Oh Y, Tan SH, Ng ML, Shim W, Wong P, Liew R. Generation of patient-specific induced pluripotent stem cell-derived cardiomyocytes as a cellular model of arrhythmogenic right ventricular cardiomyopathy. Eur Heart J 2012; 34:1122-33. [PMID: 22798562 DOI: 10.1093/eurheartj/ehs226] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
AIMS Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disorder associated with sudden cardiac death. Its pathophysiology is still poorly understood. We aimed to produce an in vitro cellular model of ARVC using patient-specific induced pluripotent stem cell (iPSC)-derived cardiomyocytes and determine whether the model could recapitulate key features of the disease phenotype. METHODS AND RESULTS Dermal fibroblasts were obtained from a 30-year-old man with a clinical diagnosis of ARVC, harbouring a plakophilin 2 (PKP2) gene mutation. Four stable iPSC lines were generated using retroviral reprogramming, and functional cardiomyocytes were derived. Gene expression levels of desmosomal proteins (PKP2 and plakoglobin) in cardiomyocytes from ARVC-iPSCs were significantly lower compared with cardiomyocytes from control iPSCs (P< 0.01); there were no significant differences in the expression of desmoplakin, N-cadherin, and connexin 43 between the two groups. Cardiomyocytes derived from ARVC-iPSCs exhibited markedly reduced immunofluorescence signals when stained for PKP2 and plakoglobin, but similar levels of staining for desmoplakin, N-cadherin, and connexin 43 compared with control cardiomyocytes. Transmission electron microscopy showed that ARVC-iPSC cardiomyocytes were larger and contained darker lipid droplets compared with control cardiomyocytes. After 2 weeks of cell exposure to adiopgenic differentiation medium, ARVC-iPSC cardiomyocytes were found to contain a significantly greater amount of lipid, calculated using Oil Red O staining, compared with controls (734 ± 35.6 vs. 8.1 ± 0.49 a.u., respectively; n = 7, P = 0.001). CONCLUSION Patient-specific iPSC-derived cardiomyocytes display key features of ARVC, including reduced cell surface localization of desmosomal proteins and a more adipogenic phenotype.
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Affiliation(s)
- Dongrui Ma
- Research and Development Unit (RDU), National Heart Centre Singapore, 17 Third Hospital Avenue, Singapore 168752, Singapore
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217
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Kirchner F, Schuetz A, Boldt LH, Martens K, Dittmar G, Haverkamp W, Thierfelder L, Heinemann U, Gerull B. Molecular insights into arrhythmogenic right ventricular cardiomyopathy caused by plakophilin-2 missense mutations. ACTA ACUST UNITED AC 2012; 5:400-11. [PMID: 22781308 DOI: 10.1161/circgenetics.111.961854] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiac disorder mainly caused by dominant mutations in several components of the cardiac desmosome including plakophilin-2 (PKP2), the most prevalent disease gene. Little is known about the underlying genetic and molecular mechanisms of missense mutations located in the armadillo (ARM) domains of PKP2, as well as their consequences on human cardiac pathology. METHODS AND RESULTS We focused on in vivo and in vitro studies of the PKP2 founder mutation c.2386T>C (p.C796R), and demonstrated in cardiac tissue from 2 related mutation carriers a patchy expression pattern ranging from unchanged to totally absent immunoreactive signals of PKP2 and other desmosomal proteins. In vitro expression analysis of mutant PKP2 in cardiac derived HL-1 cells revealed unstable proteins that fail to interact with desmoplakin and are targeted by degradation involving calpain proteases. Bacterial expression, crystallization, and structural modeling of mutated proteins impacting different ARM domains and helices of PKP2 confirmed their instability and degradation, resulting in the same remaining protein fragment that was crystallized and used to model the entire ARM domain of PKP2. CONCLUSIONS The p.C796R and other ARVC-related PKP2 mutations indicate loss of function effects by intrinsic instability and calpain proteases mediated degradation in in vitro model systems, suggesting haploinsufficiency as the most likely cause for the genesis of dominant ARVC due to mutations in PKP2.
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218
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Rizzo S, Lodder EM, Verkerk AO, Wolswinkel R, Beekman L, Pilichou K, Basso C, Remme CA, Thiene G, Bezzina CR. Intercalated disc abnormalities, reduced Na(+) current density, and conduction slowing in desmoglein-2 mutant mice prior to cardiomyopathic changes. Cardiovasc Res 2012; 95:409-18. [PMID: 22764152 DOI: 10.1093/cvr/cvs219] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
AIMS Mutations in genes encoding desmosomal proteins have been implicated in the pathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC). However, the consequences of these mutations in early disease stages are unknown. We investigated whether mutation-induced intercalated disc remodelling impacts on electrophysiological properties before the onset of cell death and replacement fibrosis. METHODS AND RESULTS Transgenic mice with cardiac overexpression of mutant Desmoglein2 (Dsg2) Dsg2-N271S (Tg-NS/L) were studied before and after the onset of cell death and replacement fibrosis. Mice with cardiac overexpression of wild-type Dsg2 and wild-type mice served as controls. Assessment by electron microscopy established that intercellular space widening at the desmosomes/adherens junctions occurred in Tg-NS/L mice before the onset of necrosis and fibrosis. At this stage, epicardial mapping in Langendorff-perfused hearts demonstrated prolonged ventricular activation time, reduced longitudinal and transversal conduction velocities, and increased arrhythmia inducibility. A reduced action potential (AP) upstroke velocity due to a lower Na(+) current density was also observed at this stage of the disease. Furthermore, co-immunoprecipitation demonstrated an in vivo interaction between Dsg2 and the Na(+) channel protein Na(V)1.5. CONCLUSION Intercellular space widening at the level of the intercalated disc (desmosomes/adherens junctions) and a concomitant reduction in AP upstroke velocity as a consequence of lower Na(+) current density lead to slowed conduction and increased arrhythmia susceptibility at disease stages preceding the onset of necrosis and replacement fibrosis. The demonstration of an in vivo interaction between Dsg2 and Na(V)1.5 provides a molecular pathway for the observed electrical disturbances during the early ARVC stages.
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Affiliation(s)
- Stefania Rizzo
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua 35121, Italy
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219
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Thiene G. Arrhythmogenic cardiomyopathy: from autopsy to genes and transgenic mice (SCVP Achievement Award Lecture, San Antonio, TX, February 27, 2011). Cardiovasc Pathol 2012; 21:229-39. [DOI: 10.1016/j.carpath.2011.09.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 09/30/2011] [Indexed: 10/15/2022] Open
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Abstract
Sudden cardiac death (SCD), a sudden pulseless condition due to cardiac arrhythmia, remains a major public health problem despite recent progress in the treatment and prevention of overall coronary heart disease. In this review, we examine the evidence for genetic susceptibility to SCD in order to provide biological insight into the pathogenesis of this devastating disease and to explore the potential for genetics to impact clinical management of SCD risk. Both candidate gene approaches and unbiased genome-wide scans have identified novel biological pathways contributing to SCD risk. Although risk stratification in the general population remains an elusive goal, several studies point to the potential utility of these common genetic variants in high-risk individuals. Finally, we highlight novel methodological approaches to deciphering the molecular mechanisms involved in arrhythmogenesis. Although further epidemiological and clinical applications research is needed, it is increasingly clear that genetic approaches are yielding important insights into SCD that may impact the public health burden imposed by SCD and its associated outcomes.
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Affiliation(s)
- Dan E Arking
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21209, USA.
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221
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Cooperative coupling of cell-matrix and cell-cell adhesions in cardiac muscle. Proc Natl Acad Sci U S A 2012; 109:9881-6. [PMID: 22675119 DOI: 10.1073/pnas.1203007109] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Adhesion between cardiac myocytes is essential for the heart to function as an electromechanical syncytium. Although cell-matrix and cell-cell adhesions reorganize during development and disease, the hierarchical cooperation between these subcellular structures is poorly understood. We reasoned that, during cardiac development, focal adhesions mechanically stabilize cells and tissues during myofibrillogenesis and intercalated disc assembly. As the intercalated disc matures, we postulated that focal adhesions disassemble as systolic stresses are transmitted intercellularly. Finally, we hypothesized that pathological remodeling of cardiac microenvironments induces excessive mechanical loading of intercalated discs, leading to assembly of stabilizing focal adhesions adjacent to the junction. To test our model, we engineered μtissues composed of two ventricular myocytes on deformable substrates of tunable elasticity to measure the dynamic organization and functional remodeling of myofibrils, focal adhesions, and intercalated discs as cooperative ensembles. Maturing μtissues increased systolic force while simultaneously developing into an electromechanical syncytium by disassembling focal adhesions at the cell-cell interface and forming mature intercalated discs that transmitted the systolic load. We found that engineering the microenvironment to mimic fibrosis resulted in focal adhesion formation adjacent to the cell-cell interface, suggesting that the intercalated disc required mechanical reinforcement. In these pathological microenvironments, μtissues exhibited further evidence of maladaptive remodeling, including lower work efficiency, longer contraction cycle duration, and weakened relationships between cytoskeletal organization and force generation. These results suggest that the cooperative balance between cell-matrix and cell-cell adhesions in the heart is guided by an architectural and functional hierarchy established during development and disrupted during disease.
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Groeneweg JA, Hauer RNW. Noninvasive parameters for evaluation of activation delay in arrhythmogenic cardiomyopathy. Circ Arrhythm Electrophysiol 2012; 5:453-5. [PMID: 22715235 DOI: 10.1161/circep.112.971895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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223
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Quarta G, Elliott PM. Diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy. Rev Esp Cardiol 2012; 65:599-605. [PMID: 22622265 DOI: 10.1016/j.recesp.2012.02.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 02/09/2012] [Indexed: 10/28/2022]
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Swope D, Li J, Muller EJ, Radice GL. Analysis of a Jup hypomorphic allele reveals a critical threshold for postnatal viability. Genesis 2012; 50:717-27. [PMID: 22522917 DOI: 10.1002/dvg.22034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 12/25/2022]
Abstract
Mutations in the human Jup gene cause arrhythmogenic right ventricular cardiomyopathy (ARVC), a heart muscle disease that often leads to sudden cardiac death. Inactivation of the murine Jup gene (also known as plakoglobin) results in embryonic lethality due to cardiac rupture. In an effort to generate a conditional knockout allele, a neomycin cassette was introduced into the murine plakoglobin (PG) gene. This allele (PG F(N)) functions as a hypomorph when combined with a null allele (PG Δ). About half of the PG F(N)/Δ animals were smaller than their littermates and died before weaning age, whereas the remaining PG F(N)/Δ animals survived. Despite the reduced levels of PG in the heart, there were no signs of cardiomyopathy or cardiac dysfunction as determined by echocardiography. Importantly, the PG homolog, β-catenin (CTNNB1), was increased in the PG F(N)/Δ hearts. In addition to its structural role as part of the N-cadherin/catenin adhesion complex, β-catenin is a downstream effector of Wnt signaling. However, no change in β-catenin/TCF reporter activity was observed in PG F(N)/Δ embryos suggesting that excess β-catenin was not likely causing increased transcription of Wnt/β-catenin target genes. These data suggest novel function(s) for PG beyond the heart and define a critical threshold of PG expression that is necessary for postnatal survival.
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Affiliation(s)
- David Swope
- Department of Medicine, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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225
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Abstract
PURPOSE OF REVIEW Connexins are the pore forming subunits of gap junction channels. They are essential for cardiac action potential propagation. Connexins are modified at the transcriptional or posttranslational levels under pathological states such as cardiac hypertrophy or ischemia, thus contributing to the arrhythmogenic substrate. However, the relation between nucleotide substitutions in the connexin gene and the occurrence of cardiac arrhythmias remains largely unexplored. RECENT FINDINGS Recent studies have reported an association between nucleotide substitutions in the connexin40 (Cx40) and connexin43 (Cx43) genes (GJA5 and GJA1, respectively) and cardiac arrhythmias. Of note, however, germline mutations in Cx43 are considered causative of oculodentodigital dysplasia, a pleiotropic syndrome wherein cardiac manifestations are notoriously absent. SUMMARY Here, we review some of the current knowledge on the association between cardiac connexins and inherited arrhythmias.
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Affiliation(s)
- Mario Delmar
- The Leon H Charney Division of Cardiology, New York University School of Medicine, New York, New York 10016, USA.
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226
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Rickelt S, Pieperhoff S. Mutations with pathogenic potential in proteins located in or at the composite junctions of the intercalated disk connecting mammalian cardiomyocytes: a reference thesaurus for arrhythmogenic cardiomyopathies and for Naxos and Carvajal diseases. Cell Tissue Res 2012; 348:325-33. [PMID: 22450909 PMCID: PMC3349860 DOI: 10.1007/s00441-012-1365-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 02/03/2012] [Indexed: 01/30/2023]
Abstract
In the past decade, an avalanche of findings and reports has correlated arrhythmogenic ventricular cardiomyopathies (ARVC) and Naxos and Carvajal diseases with certain mutations in protein constituents of the special junctions connecting the polar regions (intercalated disks) of mature mammalian cardiomyocytes. These molecules, apparently together with some specific cytoskeletal proteins, are components of (or interact with) composite junctions. Composite junctions contain the amalgamated fusion products of the molecules that, in other cell types and tissues, occur in distinct separate junctions, i.e. desmosomes and adherens junctions. As the pertinent literature is still in an expanding phase and is obviously becoming important for various groups of researchers in basic cell and molecular biology, developmental biology, histology, physiology, cardiology, pathology and genetics, the relevant references so far recognized have been collected and are presented here in the following order: desmocollin-2 (Dsc2, DSC2), desmoglein-2 (Dsg2, DSG2), desmoplakin (DP, DSP), plakoglobin (PG, JUP), plakophilin-2 (Pkp2, PKP2) and some non-desmosomal proteins such as transmembrane protein 43 (TMEM43), ryanodine receptor 2 (RYR2), desmin, lamins A and C, striatin, titin and transforming growth factor-β3 (TGFβ3), followed by a collection of animal models and of reviews, commentaries, collections and comparative studies.
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Affiliation(s)
- Steffen Rickelt
- Helmholtz Group for Cell Biology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, Building TP4, 69120 Heidelberg, Germany
- Progen Biotechnik, Heidelberg, Germany
| | - Sebastian Pieperhoff
- BHF Centre for Cardiovascular Science, The Queen’s Medical Research Institute, University of Edinburgh, 47 Little France Crescent, EH164TJ Edinburgh, Scotland UK
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Desplantez T, McCain ML, Beauchamp P, Rigoli G, Rothen-Rutishauser B, Parker KK, Kleber AG. Connexin43 ablation in foetal atrial myocytes decreases electrical coupling, partner connexins, and sodium current. Cardiovasc Res 2012; 94:58-65. [PMID: 22287588 PMCID: PMC3307380 DOI: 10.1093/cvr/cvs025] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 01/10/2012] [Accepted: 01/23/2012] [Indexed: 11/15/2022] Open
Abstract
AIMS Remodelling and regional gradients in expression of connexins (Cx) are thought to contribute to atrial electrical dysfunction and atrial fibrillation. We assessed the effect of interaction between Cx43, Cx40, and Cx45 on atrial cell-to-cell coupling and inward Na current (I(Na)) in engineered pairs of atrial myocytes derived from wild-type mice (Cx43(+/+)) and mice with genetic ablation of Cx43 (Cx43(-/-)). METHODS AND RESULTS Cell pairs were engineered by microcontact printing from atrial Cx43(+/+) and Cx43(-/-) murine myocytes (1 day before birth, 3-5 days in culture). Dual and single voltage clamp were used to measure intercellular electrical conductance, g(j), and its dependence on transjunctional voltage, V(j), single gap junction channel conductances, and I(Na). 3D reconstructions of Cx43, Cx40, and Cx45 immunosignals in gap junctions were made from confocal slices. Full genetic Cx43 ablation produced a decrease in immunosignals of Cx40 to 62 ± 10% (mean ± SE; n= 17) and Cx45 to 66 ± 8% (n= 16). G(j) decreased from 80 ± 9 nS (Cx43(+/+), n= 17) to 24 ± 2 nS (Cx43(-/-), n= 35). Single channel analysis showed a shift in the main peak of the channel histogram from 49 ± 1.7 nS (Cx43(+/+)) to 67 ± 1.8 nS (Cx43(-/-)) with a second minor peak appearing at 27 ± 1.5 pS. The dependence of g(j) on V(j) decreased with Cx43 ablation. Importantly, peak I(Na) decreased from -350 ± 44 pA/pF (Cx43(+/+)) to -154 ± 28 pA/pF (Cx43(-/-)). CONCLUSIONS The dependence of Cx40, Cx45, and I(Na) on Cx43 expression indicates a complex interaction between connexins and I(Na) in the atrial intercalated discs that is likely to be of relevance for arrhythmogenesis.
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Affiliation(s)
| | - Megan L. McCain
- Disease Biophysics Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | | | | | | | - Kevin Kit Parker
- Disease Biophysics Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Andre G. Kleber
- Department of Physiology, University of Bern, Bern, Switzerland
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Functional effects of the TMEM43 Ser358Leu mutation in the pathogenesis of arrhythmogenic right ventricular cardiomyopathy. BMC MEDICAL GENETICS 2012; 13:21. [PMID: 22458570 PMCID: PMC3352248 DOI: 10.1186/1471-2350-13-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 03/29/2012] [Indexed: 12/31/2022]
Abstract
Background The Ser358Leu mutation in TMEM43, encoding an inner nuclear membrane protein, has been implicated in arrhythmogenic right ventricular cardiomyopathy (ARVC). The pathogenetic mechanisms of this mutation are poorly understood. Methods To determine the frequency of TMEM43 mutations as a cause of ARVC, we screened 11 ARVC families for mutations in TMEM43 and five desmosomal genes previously implicated in the disease. Functional studies were performed in COS-7 cells transfected with wildtype, mutant, and 1:2 wildtype:mutant TMEM43 to determine the effect of the Ser358Leu mutation on the stability and cellular localization of TMEM43 and other nuclear envelope and desmosomal proteins, assessed by solubility assays and immunofluorescence imaging. mRNA expression was assessed of genes potentially affected by dysfunction of the nuclear lamina. Results Three novel mutations in previously documented desmosomal genes, but no mutations in TMEM43, were identified. COS-7 cells transfected with mutant TMEM43 exhibited no change in desmosomal stability. Stability and nuclear membrane localization of mutant TMEM43 and of lamin B and emerin were normal. Mutant TMEM43 did not alter the expression of genes located on chromosome 13, previously implicated in nuclear envelope protein mutations leading to skeletal muscular dystrophies. Conclusions Mutant TMEM43 exhibits normal cellular localization and does not disrupt integrity and localization of other nuclear envelope and desmosomal proteins. The pathogenetic role of TMEM43 mutations in ARVC remains uncertain.
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229
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Loss of cadherin-binding proteins β-catenin and plakoglobin in the heart leads to gap junction remodeling and arrhythmogenesis. Mol Cell Biol 2012; 32:1056-67. [PMID: 22252313 DOI: 10.1128/mcb.06188-11] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Arrhythmic right ventricular cardiomyopathy (ARVC) is a hereditary heart muscle disease that causes sudden cardiac death (SCD) in young people. Almost half of ARVC patients have a mutation in genes encoding cell adhesion proteins of the desmosome, including plakoglobin (JUP). We previously reported that cardiac tissue-specific plakoglobin (PG) knockout (PG CKO) mice have no apparent conduction abnormality and survive longer than expected. Importantly, the PG homolog, β-catenin (CTNNB1), showed increased association with the gap junction protein connexin43 (Cx43) in PG CKO hearts. To determine whether β-catenin is required to maintain cardiac conduction in the absence of PG, we generated mice lacking both PG and β-catenin specifically in the heart (i.e., double knockout [DKO]). The DKO mice exhibited cardiomyopathy, fibrous tissue replacement, and conduction abnormalities resulting in SCD. Loss of the cadherin linker proteins resulted in dissolution of the intercalated disc (ICD) structure. Moreover, Cx43-containing gap junction plaques were reduced at the ICD, consistent with the arrhythmogenicity of the DKO hearts. Finally, ambulatory electrocardiogram monitoring captured the abrupt onset of spontaneous lethal ventricular arrhythmia in the DKO mice. In conclusion, these studies demonstrate that the N-cadherin-binding partners, PG and β-catenin, are indispensable for maintaining mechanoelectrical coupling in the heart.
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230
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Munkholm J, Christensen AH, Svendsen JH, Andersen CB. Usefulness of immunostaining for plakoglobin as a diagnostic marker of arrhythmogenic right ventricular cardiomyopathy. Am J Cardiol 2012; 109:272-5. [PMID: 22036107 DOI: 10.1016/j.amjcard.2011.08.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/30/2011] [Accepted: 08/30/2011] [Indexed: 02/07/2023]
Abstract
The clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) is often challenging due to phenotypic variation, reduced/age-related penetrance, and lack of a diagnostic test. A single report has suggested quantitative myocardial immunoanalysis for the desmosomal protein plakoglobin as a diagnostic test with high sensitivity and specificity. We performed immunohistochemistry for plakoglobin and a control protein on myocardial biopsies with fibrofatty replacements from 50 consecutive, unrelated patients. The clinical, genetic, and immunohistochemical data were evaluated by independent observers in a blinded manner. The immunohistochemical and clinical diagnoses were compared and the sensitivity, specificity, and predictive values calculated. Our analysis showed 37 samples (74%) with a reduced immunosignal for plakoglobin. Of the 34 patients with a clinical diagnosis of ARVC, 29 displayed a reduced plakoglobin signal. Of the 14 patients with a clinical diagnosis other than ARVC, 6 displayed a reduced signal. Two patients were excluded from further analysis. A sensitivity of 85%, a specificity of 57%, a positive predictive value of 83%, and a negative predictive value of 62% were found. In conclusion, immunohistochemical analysis for plakoglobin, applied as a diagnostic test for ARVC, seems associated with a relatively high sensitivity, but limited specificity, and although additional validation is required, we advocate caution in basing clinical decision-making on the proposed diagnostic test.
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231
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Monteforte N, Napolitano C, Priori SG. Genetics and arrhythmias: diagnostic and prognostic applications. Rev Esp Cardiol 2012; 65:278-86. [PMID: 22245453 DOI: 10.1016/j.recesp.2011.10.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 10/09/2011] [Indexed: 10/14/2022]
Abstract
This review article discusses the genetic bases of cardiac arrest with a specific focus on cardiac channelopathies and right ventricular cardiomyopathy. We review the appropriate use of genetic testing in those patients suspected to have inherited cardiac arrhythmias, highlighting the importance of most genotype-phenotype correlations for risk stratification. The article also presents the most recent views on diagnostic criteria and flowcharts for treatment of patients with inherited arrhythmogenic diseases.
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Affiliation(s)
- Nicola Monteforte
- Medicina Molecolare, IRCCS Fondazione Salvatore Maugeri, Pavía, Italy
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232
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Gomes J, Finlay M, Ahmed AK, Ciaccio EJ, Asimaki A, Saffitz JE, Quarta G, Nobles M, Syrris P, Chaubey S, McKenna WJ, Tinker A, Lambiase PD. Electrophysiological abnormalities precede overt structural changes in arrhythmogenic right ventricular cardiomyopathy due to mutations in desmoplakin-A combined murine and human study. Eur Heart J 2012; 33:1942-53. [PMID: 22240500 PMCID: PMC3409421 DOI: 10.1093/eurheartj/ehr472] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIMS Anecdotal observations suggest that sub-clinical electrophysiological manifestations of arrhythmogenic right ventricular cardiomyopathy (ARVC) develop before detectable structural changes ensue on cardiac imaging. To test this hypothesis, we investigated a murine model with conditional cardiac genetic deletion of one desmoplakin allele (DSP ±) and compared the findings to patients with non-diagnostic features of ARVC who carried mutations in desmoplakin. METHODS AND RESULTS Murine: the DSP (±) mice underwent electrophysiological, echocardiographic, and immunohistochemical studies. They had normal echocardiograms but delayed conduction and inducible ventricular tachycardia associated with mislocalization and reduced intercalated disc expression of Cx43. Sodium current density and myocardial histology were normal at 2 months of age. Human: ten patients with heterozygous mutations in DSP without overt structural heart disease (DSP+) and 12 controls with supraventricular tachycardia were studied by high-density electrophysiological mapping of the right ventricle. Using a standard S(1)-S(2) protocol, restitution curves of local conduction and repolarization parameters were constructed. Significantly greater mean increases in delay were identified particularly in the outflow tract vs. controls (P< 0.01) coupled with more uniform wavefront progression. The odds of a segment with a maximal activation-repolarization interval restitution slope >1 was 99% higher (95% CI: 13%; 351%, P = 0.017) in DSP+ vs. controls. Immunostaining revealed Cx43 mislocalization and variable Na channel distribution. CONCLUSION Desmoplakin disease causes connexin mislocalization in the mouse and man preceding any overt histological abnormalities resulting in significant alterations in conduction-repolarization kinetics prior to morphological changes detectable on conventional cardiac imaging. Haploinsufficiency of desmoplakin is sufficient to cause significant Cx43 mislocalization. Changes in sodium current density and histological abnormalities may contribute to a worsening phenotype or disease but are not necessary to generate an arrhythmogenic substrate. This has important implications for the earlier diagnosis of ARVC and risk stratification.
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233
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Abstract
The right ventricular apex (RVA) is a potential hot spot for development of cardiac rhythm anomalies. Many conditions, including arrhythmogenic right ventricular cardiomyopathy and Brugada's syndrome affect the RVA, and further, the RVA remains an incompletely characterized pacing region. Whether there are structural reasons underlying these conduction properties remains unsettled. In the current study, we characterize the mechanical strains and structural attributes of the right ventricular wall, and test the hypothesis that the right ventricular apex experiences heterogeneous strain distributions and altered fiber organization, and is thus susceptible to conduction alterations. Electromechanical wave imaging (EWI), or elastography, of hearts was used to quantify mechanical strains occurring through a cardiac cycle. Histological and immunofluorescence imaging techniques were used to examine cardiac wall structure and arrangement of junctional proteins. Right ventricular mechanical strains were elevated and sustained throughout systole, compared to the left ventricle and septum. Heterogeneous strain distributions, myocardial fiber disarray, and altered junctional protein localization occured at the RVA. Disarray and altered strain distributions suggest decreased structural strength at the right ventricular apex in particular and increased mechanical impositions in the right ventricle, respectively. Thus, these data demonstrate why the right ventricular apex may be particularly vulnerable to conduction abnormalities.
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234
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van der Smagt JJ, van der Zwaag PA, van Tintelen JP, Cox MG, Wilde AA, van Langen IM, Ummels A, Hennekam F, Dooijes D, Gerbens F, Bikker H, Hauer RN, Doevendans PA. Clinical and Genetic Characterization of Patients with Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Caused by a Plakophilin-2 Splice Mutation. Cardiology 2012; 123:181-9. [DOI: 10.1159/000342717] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 07/18/2012] [Indexed: 11/19/2022]
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235
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Mezzano V, Sheikh F. Cell-cell junction remodeling in the heart: possible role in cardiac conduction system function and arrhythmias? Life Sci 2011; 90:313-21. [PMID: 22227473 DOI: 10.1016/j.lfs.2011.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 11/28/2022]
Abstract
Anchoring cell-cell junctions (desmosomes, fascia adherens) play crucial roles in maintaining mechanical integrity of cardiac muscle cells and tissue. Genetic mutations and/or loss of critical components in these macromolecular structures are increasingly being associated with arrhythmogenic cardiomyopathies; however, their specific roles have been primarily attributed to effects within the working (ventricular) cardiac muscle. Growing evidence also points to a key role for anchoring cell-cell junction components in cardiac muscle cells of the cardiac conduction system. This is not only evidenced by the molecular and ultra-structural presence of anchoring cell junctions in specific compartments/structures of the cardiac conduction system (sinoatrial node, atrioventricular node, His-Purkinje system), but also because conduction system-related arrhythmias can be found in humans and mouse models of cardiomyopathies harboring defects and/or mutations in key anchoring cell-cell junction proteins. These studies emphasize the clinical need to understand the molecular and cellular role(s) for anchoring cell-cell junctions in cardiac conduction system function and arrhythmias. This review will focus on (i) experimental findings that underline an important role for anchoring cell-cell junctions in the cardiac conduction system, (ii) insights regarding involvement of these structures in age-related cardiac remodeling of the conduction system, (iii) summarizing available genetic mouse models that can target cardiac conduction system structures and (iv) implications of these findings on future therapies for arrhythmogenic heart diseases.
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Affiliation(s)
- Valeria Mezzano
- Department of Medicine (Cardiology Division), University of California-San Diego, La Jolla, CA 92093, USA
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236
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Quarta G, Syrris P, Ashworth M, Jenkins S, Zuborne Alapi K, Morgan J, Muir A, Pantazis A, McKenna WJ, Elliott PM. Mutations in the Lamin A/C gene mimic arrhythmogenic right ventricular cardiomyopathy. Eur Heart J 2011; 33:1128-36. [PMID: 22199124 DOI: 10.1093/eurheartj/ehr451] [Citation(s) in RCA: 186] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AIMS Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease predominantly caused by mutations in desmosomal protein genes. Lamin A/C gene (LMNA) mutations are associated with dilated cardiomyopathy, conduction abnormalities and high incidence of sudden cardiac death. In this study, we screened a large cohort of ARVC patients for LMNA mutations. METHODS AND RESULTS One hundred and eight patients from unrelated families with borderline (n = 27) or definite (n = 81) diagnosis of ARVC were genetically tested for five desmosomal genes and LMNA. Sixty-one (56.5%) were positive for desmosomal gene mutations. Standard polymerase chain reaction (PCR) amplification of the 12 protein-coding LMNA exons was performed and mutational screening performed by direct sequencing. Four patients (4%) without desmosomal gene mutations carried LMNA variants. Three had severe right ventricular involvement, and during follow-up three died (two suddenly and one from congestive heart failure); all three had conduction abnormalities on resting 12-lead electrocardiogram (ECG). Myocardial tissue from two patients showed myocyte loss and fibro-fatty replacement. In one of these, immunohistochemical staining with antibody to plakoglobin showed reduced/absent staining of the intercalated discs in the myocardium. CONCLUSION Lamin A/C gene mutations can be found in severe forms of ARVC. Lamin A/C gene should be added to desmosomal genes when genetically testing patients with suspected ARVC, particularly when they also have ECG evidence for conduction disease.
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Affiliation(s)
- Giovanni Quarta
- The Heart Hospital, University College London Hospitals Trust, 16-18 Westmoreland Street, London W1G 8PH, UK
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Van Norstrand DW, Asimaki A, Rubinos C, Dolmatova E, Srinivas M, Tester DJ, Saffitz JE, Duffy HS, Ackerman MJ. Connexin43 mutation causes heterogeneous gap junction loss and sudden infant death. Circulation 2011; 125:474-81. [PMID: 22179534 DOI: 10.1161/circulationaha.111.057224] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND An estimated 10% to 15% of sudden infant death syndrome (SIDS) cases may stem from channelopathy-mediated lethal arrhythmias. Loss of the GJA1-encoded gap junction channel protein connexin43 is known to underlie formation of lethal arrhythmias. GJA1 mutations have been associated with cardiac diseases, including atrial fibrillation. Therefore, GJA1 is a plausible candidate gene for premature sudden death. METHODS AND RESULTS GJA1 open reading frame mutational analysis was performed with polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing on DNA from 292 SIDS cases. Immunofluorescence and dual whole-cell patch-clamp studies were performed to determine the functionality of mutant gap junctions. Immunostaining for gap junction proteins was performed on SIDS-associated paraffin-embedded cardiac tissue. Two rare, novel missense mutations, E42K and S272P, were detected in 2 of 292 SIDS cases, a 2-month-old white boy and a 3-month-old white girl, respectively. Analysis of the E42K victim's parental DNA demonstrated a de novo mutation. Both mutations involved highly conserved residues and were absent in >1000 ethnically matched reference alleles. Immunofluorescence demonstrated no trafficking abnormalities for either mutation, and S272P demonstrated wild-type junctional conductance. However, junctional conductance measurements for the E42K mutation demonstrated a loss of function not rescued by wild type. Moreover, the E42K victim's cardiac tissue demonstrated a mosaic immunostaining pattern for connexin43 protein. CONCLUSIONS This study provides the first molecular and functional evidence implicating a GJA1 mutation as a novel pathogenic substrate for SIDS. E42K-connexin43 demonstrated a trafficking-independent reduction in junctional coupling in vitro and a mosaic pattern of mutational DNA distribution in deceased cardiac tissue, suggesting a novel mechanism of connexin43-associated sudden death.
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238
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Leone O, Veinot JP, Angelini A, Baandrup UT, Basso C, Berry G, Bruneval P, Burke M, Butany J, Calabrese F, d'Amati G, Edwards WD, Fallon JT, Fishbein MC, Gallagher PJ, Halushka MK, McManus B, Pucci A, Rodriguez ER, Saffitz JE, Sheppard MN, Steenbergen C, Stone JR, Tan C, Thiene G, van der Wal AC, Winters GL. 2011 consensus statement on endomyocardial biopsy from the Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology. Cardiovasc Pathol 2011; 21:245-74. [PMID: 22137237 DOI: 10.1016/j.carpath.2011.10.001] [Citation(s) in RCA: 361] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/28/2011] [Accepted: 10/07/2011] [Indexed: 01/04/2023] Open
Abstract
The Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology have produced this position paper concerning the current role of endomyocardial biopsy (EMB) for the diagnosis of cardiac diseases and its contribution to patient management, focusing on pathological issues, with these aims: • Determining appropriate EMB use in the context of current diagnostic strategies for cardiac diseases and providing recommendations for its rational utilization • Providing standard criteria and guidance for appropriate tissue triage and pathological analysis • Promoting a team approach to EMB use, integrating the competences of pathologists, clinicians, and imagers.
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Affiliation(s)
- Ornella Leone
- U.O. di Anatomia ed Istologia Patologica, Azienda Ospedaliero-Universitaria S.Orsola-Malpighi, Bologna, Italy.
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239
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Smith W. Guidelines for the Diagnosis and Management of Arrhythmogenic Right Ventricular Cardiomyopathy. Heart Lung Circ 2011; 20:757-60. [DOI: 10.1016/j.hlc.2011.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/28/2011] [Accepted: 07/30/2011] [Indexed: 01/09/2023]
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Abstract
Arrhythmogenic cardiomyopathy (AC) is a clinically and genetically heterogeneous disorder of heart muscle that is associated with ventricular arrhythmias and risk of sudden cardiac death, particularly in the young and athletes. Mutations in five genes that encode major components of the desmosomes, namely junction plakoglobin, desmoplakin, plakophilin-2, desmoglein-2, and desmocollin-2, have been identified in approximately half of affected probands. AC is, therefore, commonly considered a 'desmosomal' disease. No single test is sufficiently specific to establish a diagnosis of AC. The diagnostic criteria for AC were revised in 2010 to improve sensitivity, but maintain specificity. Quantitative parameters were introduced and identification of a pathogenic mutation in a first-degree relative has become a major diagnostic criterion. Caution in the interpretation of screening results is highly recommended because a 'pathogenic' mutation is difficult to define. Experimental data confirm that this genetically determined cardiomyopathy develops after birth because of progressive myocardial dystrophy, and is initiated by cardiomyocyte necrosis; cellular and animal models are necessary to gain insight into the cascade of underlying molecular events. Crosstalk from the desmosome to the nucleus, gap junctions, and ion channels is under investigation, to move from symptomatic to targeted therapy, with the ultimate aim to stop disease onset and progression.
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241
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Affiliation(s)
- Angeliki Asimaki
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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242
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McCain ML, Desplantez T, Geisse NA, Rothen-Rutishauser B, Oberer H, Parker KK, Kleber AG. Cell-to-cell coupling in engineered pairs of rat ventricular cardiomyocytes: relation between Cx43 immunofluorescence and intercellular electrical conductance. Am J Physiol Heart Circ Physiol 2011; 302:H443-50. [PMID: 22081700 DOI: 10.1152/ajpheart.01218.2010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gap junctions are composed of connexin (Cx) proteins, which mediate intercellular communication. Cx43 is the dominant Cx in ventricular myocardium, and Cx45 is present in trace amounts. Cx43 immunosignal has been associated with cell-to-cell coupling and electrical propagation, but no studies have directly correlated Cx43 immunosignal to electrical cell-to-cell conductance, g(j), in ventricular cardiomyocyte pairs. To assess the correlation between Cx43 immunosignal and g(j), we developed a method to determine both parameters from the same cell pair. Neonatal rat ventricular cardiomyocytes were seeded on micropatterned islands of fibronectin. This allowed formation of cell pairs with reproducible shapes and facilitated tracking of cell pair locations. Moreover, cell spreading was limited by the fibronectin pattern, which allowed us to increase cell height by reducing the surface area of the pattern. Whole cell dual voltage clamp was used to record g(j) of cell pairs after 3-5 days in culture. Fixation of cell pairs before removal of patch electrodes enabled preservation of cell morphology and offline identification of patched pairs. Subsequently, pairs were immunostained, and the volume of junctional Cx43 was quantified using confocal microscopy, image deconvolution, and three-dimensional reconstruction. Our results show a linear correlation between g(j) and Cx43 immunosignal within a range of 8-50 nS.
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Affiliation(s)
- Megan L McCain
- Department of Physiology, University of Bern, Bern, Switzerland
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243
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Milan DJ, Acha MR. Recovery of myocardial tissue from extracted leads. Heart Rhythm 2011; 9:405-6. [PMID: 22063082 DOI: 10.1016/j.hrthm.2011.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Indexed: 11/15/2022]
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244
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Calkins H. Use of mouse models to evaluate novel therapeutic approaches to treatment of arrhythmogenic right ventricular cardiomyopathy the future is now. J Am Coll Cardiol 2011; 57:751-2. [PMID: 21292135 DOI: 10.1016/j.jacc.2010.09.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 09/21/2010] [Indexed: 11/18/2022]
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245
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Fabritz L, Hoogendijk MG, Scicluna BP, van Amersfoorth SCM, Fortmueller L, Wolf S, Laakmann S, Kreienkamp N, Piccini I, Breithardt G, Noppinger PR, Witt H, Ebnet K, Wichter T, Levkau B, Franke WW, Pieperhoff S, de Bakker JMT, Coronel R, Kirchhof P. Load-reducing therapy prevents development of arrhythmogenic right ventricular cardiomyopathy in plakoglobin-deficient mice. J Am Coll Cardiol 2011; 57:740-50. [PMID: 21292134 DOI: 10.1016/j.jacc.2010.09.046] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 08/24/2010] [Accepted: 09/06/2010] [Indexed: 11/29/2022]
Abstract
OBJECTIVES We used a murine model of arrhythmogenic right ventricular cardiomyopathy (ARVC) to test whether reducing ventricular load prevents or slows development of this cardiomyopathy. BACKGROUND At present, no therapy exists to slow progression of ARVC. Genetically conferred dysfunction of the mechanical cell-cell connections, often associated with reduced expression of plakoglobin, is thought to cause ARVC. METHODS Littermate pairs of heterozygous plakoglobin-deficient mice (plako(+/-)) and wild-type (WT) littermates underwent 7 weeks of endurance training (daily swimming). Mice were randomized to blinded load-reducing therapy (furosemide and nitrates) or placebo. RESULTS Therapy prevented training-induced right ventricular (RV) enlargement in plako(+/-) mice (RV volume: untreated plako(+/-) 136 ± 5 μl; treated plako(+/-) 78 ± 5 μl; WT 81 ± 5 μl; p < 0.01 for untreated vs. WT and untreated vs. treated; mean ± SEM). In isolated, Langendorff-perfused hearts, ventricular tachycardias (VTs) were more often induced in untreated plako(+/-) hearts (15 of 25), than in treated plako(+/-) hearts (5 of 19) or in WT hearts (6 of 21, both p < 0.05). Epicardial mapping of the RV identified macro-re-entry as the mechanism of ventricular tachycardia. The RV longitudinal conduction velocity was reduced in untreated but not in treated plako(+/-) mice (p < 0.01 for untreated vs. WT and untreated vs. treated). Myocardial concentration of phosphorylated connexin43 was lower in plako(+/-) hearts with VTs compared with hearts without VTs and was reduced in untreated plako(+/-) compared with WT (both p < 0.05). Plako(+/-) hearts showed reduced myocardial plakoglobin concentration, whereas β-catenin and N-cadherin concentration was not changed. CONCLUSIONS Load-reducing therapy prevents training-induced development of ARVC in plako(+/-) mice.
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Affiliation(s)
- Larissa Fabritz
- Department of Cardiology and Angiology, Hospital of the University of Muenster, Germany
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246
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Gehmlich K, Syrris P, Reimann M, Asimaki A, Ehler E, Evans A, Quarta G, Pantazis A, Saffitz JE, McKenna WJ. Molecular changes in the heart of a severe case of arrhythmogenic right ventricular cardiomyopathy caused by a desmoglein-2 null allele. Cardiovasc Pathol 2011; 21:275-82. [PMID: 22036071 DOI: 10.1016/j.carpath.2011.09.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/29/2011] [Accepted: 09/16/2011] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder caused by mutations in desmosomal genes. It is often associated with life-threatening arrhythmias. Some affected individuals develop progressive heart failure and may require cardiac transplantation. METHODS The explanted heart of a young adult with end-stage heart failure due to a null allele in desmoglein-2 was studied at macroscopic, microscopic, and molecular level. Myocardial samples were probed for junctional localization of desmosomal components and the gap junction protein connexin43 by immunohistochemical staining. In addition, the protein content of desmosomal and adherens junction markers as well as connexin43 was assessed by Western blotting. RESULTS Histological analysis confirmed ARVC. Despite the loss of specific immunoreactive signal for desmosomal components at the cardiac intercalated disks (shown for plakoglobin, desmoplakin, and plakophilin-2), these proteins could be detected by Western blotting. Only for desmoglein-2, desmocollin-2, and plakoglobin were reduced protein levels observed. Adherens junction proteins were not affected. Lower phosphorylation levels were observed for connexin43; however, localization of the gap junction protein displayed regional differences. At the molecular level, disease progression was more severe in the right ventricle compared to the left ventricle. CONCLUSION Our data suggest that, in the ARVC heart, plakoglobin is mainly redistributed from the junctions to other cellular pools and that protein degradation only plays a secondary role. Homogenous changes in the phosphorylation status of connexin43 were observed in multiple ARVC samples, suggesting that this might be a general feature of the disease.
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Affiliation(s)
- Katja Gehmlich
- Institute of Cardiovascular Science and The Heart Hospital, University College London, United Kingdom.
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247
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Michaelson JE, Huang H. Cell-cell junctional proteins in cardiovascular mechanotransduction. Ann Biomed Eng 2011; 40:568-77. [PMID: 22016325 DOI: 10.1007/s10439-011-0439-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 10/07/2011] [Indexed: 01/14/2023]
Abstract
Cell-cell junctional proteins play important structural and functional roles in several physiological systems. Recent studies have illuminated key aspects in the relationship of junctional proteins with normal cell and tissue function as well as various pathologies. In this review article, the roles of cell-cell junctional proteins will be presented in four classes: adherens junctions, desmosomes, gap junctions, and tight junctions, and discussed primarily in the context of cardiovascular cell and tissue physiology and pathophysiology. The functions of the proteins are described from the perspective of mechanotransductive regulation of physiological and disease processes, with focus being laid on more biomechanical aspects, such as cell adhesion, migration, and mechanosignaling.
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Affiliation(s)
- Jarett E Michaelson
- Biomedical Engineering Departmental Office, Columbia University, New York, NY 10027, USA.
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248
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Lombardi R, da Graca Cabreira-Hansen M, Bell A, Fromm RR, Willerson JT, Marian AJ. Nuclear plakoglobin is essential for differentiation of cardiac progenitor cells to adipocytes in arrhythmogenic right ventricular cardiomyopathy. Circ Res 2011; 109:1342-53. [PMID: 22021931 DOI: 10.1161/circresaha.111.255075] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
RATIONALE Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease of desmosome proteins characterized by fibroadipogenesis in the myocardium. We have implicated signaling properties of junction protein plakoglobin (PG) in the pathogenesis of ARVC. OBJECTIVE To delineate the pathogenic role of PG in adipogenesis in ARVC. METHODS AND RESULTS We generated mice overexpressing PG, either a wildtype (PG(WT)) or a truncated (PG(TR)), known to cause ARVC, in the heart; and PG null (PG⁻/⁻) embryos. PG(WT) and PG(TR) mice exhibited fibro-adiposis, cardiac dysfunction, and premature death. Subcellular protein fractionation and immunofluorescence showed nuclear localization of PG(WT) and PG(TR) and reduced membrane localization of PG(TR). Coimmunoprecipitation showed reduced binding of PG(TR) but not PG(WT) to desmosome proteins DSP and DSG2. Transgene PG(WT) and PG(TR) were expressed in c-Kit+:Sca1+ cardiac progenitor cells (CPCs) isolated from the hearts of PG(WT) and PG(TR) by fluorescence activated cell sorting. CPCs isolated from the transgenic hearts showed enhanced adipogenesis, increased levels of adipogenic factors KLF15, C/EBP-α and noncanonical Wnt5b, and reduced level of CTGF, an inhibitor of adipogenesis. Treatment with BIO activated the canonical Wnt signaling, reversed the proadipogenic transcriptional switch and prevented adipogenesis in a dose-dependent manner. Moreover, c-Kit+ CPCs, isolated from PG⁻/⁻ embryos, were resistant to adipogenesis, expressed high mRNA levels of CTGF and other canonical Wnt signaling targets. CONCLUSIONS Nuclear PG provokes adipogenesis in c-Kit+ CPCs by repressing the canonical Wnt signaling and inducing a proadipogenic gene expression. The findings suggest that adipocytes in ARVC, at least in part, originate from c-Kit+ CPCs.
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Affiliation(s)
- Raffaella Lombardi
- Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston, Houston, Texas, USA
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249
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Pilichou K, Bezzina CR, Thiene G, Basso C. Arrhythmogenic cardiomyopathy: transgenic animal models provide novel insights into disease pathobiology. ACTA ACUST UNITED AC 2011; 4:318-26. [PMID: 21673311 DOI: 10.1161/circgenetics.110.959031] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Kalliopi Pilichou
- Department of Medical Diagnostic Sciences and Special Therapies, University of Padua, Padua, Italy
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250
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Asimaki A, Tandri H, Duffy ER, Winterfield JR, Mackey-Bojack S, Picken MM, Cooper LT, Wilber DJ, Marcus FI, Basso C, Thiene G, Tsatsopoulou A, Protonotarios N, Stevenson WG, McKenna WJ, Gautam S, Remick DG, Calkins H, Saffitz JE. Altered desmosomal proteins in granulomatous myocarditis and potential pathogenic links to arrhythmogenic right ventricular cardiomyopathy. Circ Arrhythm Electrophysiol 2011; 4:743-52. [PMID: 21859801 DOI: 10.1161/circep.111.964890] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Immunoreactive signal for the desmosomal protein plakoglobin (γ-catenin) is reduced at cardiac intercalated disks in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), a highly arrhythmogenic condition caused by mutations in genes encoding desmosomal proteins. Previously, we observed a false-positive case in which plakoglobin signal was reduced in a patient initially believed to have ARVC but who actually had cardiac sarcoidosis. Sarcoidosis can masquerade clinically as ARVC but has not been previously associated with altered desmosomal proteins. METHODS AND RESULTS We observed marked reduction in immunoreactive signal for plakoglobin at cardiac myocyte junctions in patients with sarcoidosis and giant cell myocarditis, both highly arrhythmogenic forms of myocarditis associated with granulomatous inflammation. In contrast, plakoglobin signal was not depressed in lymphocytic (nongranulomatous) myocarditis. To determine whether cytokines might promote dislocation of plakoglobin from desmosomes, we incubated cultures of neonatal rat ventricular myocytes with selected inflammatory mediators. Brief exposure to low concentrations of interleukin (IL)-17, tumor necrosis factor-α (TNF-α), and IL-6 (cytokines implicated in granulomatous myocarditis) caused translocation of plakoglobin from cell-cell junctions to intracellular sites, whereas other potent cytokines implicated in nongranulomatous myocarditis had no effect, even at much higher concentrations. We also observed myocardial expression of IL-17 and TNF-α and elevated levels of serum inflammatory mediators, including IL-6R, IL-8, monocyte chemoattractant protein 1, and macrophage inflammatory protein 1β, in patients with ARVC (all P<0.0001 compared with controls). CONCLUSIONS The results suggest novel disease mechanisms involving desmosomal proteins in granulomatous myocarditis and implicate cytokines, perhaps derived in part from the myocardium, in disruption of desmosomal proteins and arrhythmogenesis in ARVC.
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Affiliation(s)
- Angeliki Asimaki
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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