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Connexin43 cardiac gap junction remodeling: lessons from genetically engineered murine models. J Membr Biol 2012; 245:275-81. [PMID: 22722763 DOI: 10.1007/s00232-012-9448-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 06/01/2012] [Indexed: 10/28/2022]
Abstract
Sudden cardiac death is responsible for several hundred thousand deaths each year in the United States. Multiple lines of evidence suggest that perturbation of gap junction expression and function in the heart, or what has come to be known as cardiac gap junction remodeling, plays a key mechanistic role in the pathophysiology of clinically significant cardiac arrhythmias. Here we review recent studies from our laboratory using genetically engineered murine models to explore mechanisms implicated in pathologic gap junction remodeling and their proarrhythmic consequences, with a particular focus on aberrant posttranslational phosphorylation of connexin43.
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de Laat MWM, Pieper PG, Oudijk MA, Mulder BJM, Christoffels VM, Afink GB, Postma AV, Ris-Stalpers C. The Clinical and Molecular Relations Between Idiopathic Preterm Labor and Maternal Congenital Heart Defects. Reprod Sci 2012; 20:190-201. [DOI: 10.1177/1933719112446083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Petronella G. Pieper
- Department of Cardiology and Thorax Surgery, University Medical Center Groningen, Groningen, The Netherlands
| | - Martijn A. Oudijk
- Department of Obstetrics, Neonatology & Gynaecology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Vincent M. Christoffels
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, Heart Failure Research Center, Amsterdam, The Netherlands
| | - Gijs B. Afink
- Reproductive Biology Laboratory, Academic Medical Center, Amsterdam, The Netherlands
| | - Alex V. Postma
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, Heart Failure Research Center, Amsterdam, The Netherlands
| | - Carrie Ris-Stalpers
- Academic Medical Center, Women’s and Children’s Clinic, Amsterdam, The Netherlands
- Reproductive Biology Laboratory, Academic Medical Center, Amsterdam, The Netherlands
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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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104
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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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105
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Smyth JW, Vogan JM, Buch PJ, Zhang SS, Fong TS, Hong TT, Shaw RM. Actin cytoskeleton rest stops regulate anterograde traffic of connexin 43 vesicles to the plasma membrane. Circ Res 2012; 110:978-89. [PMID: 22328533 DOI: 10.1161/circresaha.111.257964] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE The intracellular trafficking of connexin 43 (Cx43) hemichannels presents opportunities to regulate cardiomyocyte gap junction coupling. Although it is known that Cx43 hemichannels are transported along microtubules to the plasma membrane, the role of actin in Cx43 forward trafficking is unknown. OBJECTIVE We explored whether the actin cytoskeleton is involved in Cx43 forward trafficking. METHODS AND RESULTS High-resolution imaging reveals that Cx43 vesicles colocalize with nonsarcomeric actin in adult cardiomyocytes. Live-cell fluorescence imaging reveals Cx43 vesicles as stationary or traveling slowly (average speed 0.09 μm/s) when associated with actin. At any time, the majority (81.7%) of vesicles travel at subkinesin rates, suggesting that actin is important for Cx43 transport. Using Cx43 containing a hemagglutinin tag in the second extracellular loop, we developed an assay to detect transport of de novo Cx43 hemichannels to the plasma membrane after release from Brefeldin A-induced endoplasmic reticulum/Golgi vesicular transport block. Latrunculin A (for specific interference of actin) was used as an intervention after reinitiation of vesicular transport. Disruption of actin inhibits delivery of Cx43 to the cell surface. Moreover, using the assay in primary cardiomyocytes, actin inhibition causes an 82% decrease (P<0.01) in de novo endogenous Cx43 delivery to cell-cell borders. In Langendorff-perfused mouse heart preparations, Cx43/β-actin complexing is disrupted during acute ischemia, and inhibition of actin polymerization is sufficient to reduce levels of Cx43 gap junctions at intercalated discs. CONCLUSIONS Actin is a necessary component of the cytoskeleton-based forward trafficking apparatus for Cx43. In cardiomyocytes, Cx43 vesicles spend a majority of their time pausing at nonsarcomeric actin rest stops when not undergoing microtubule-based transport to the plasma membrane. Deleterious effects on this interaction between Cx43 and the actin cytoskeleton during acute ischemia contribute to losses in Cx43 localization at intercalated discs.
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Affiliation(s)
- James W Smyth
- University of California San Francisco, Cardiovascular Research Institute, 555 Mission Bay Boulevard South, San Francisco, CA 94158, USA
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106
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Djordjevic V, Mitic G, Pruner I, Kovac M, Radojkovic D. Are thrombophilia more multifactorial than we thought: report of mosaicism for FII G20210A and novel FII T20061C gene variants. J Thromb Haemost 2012; 10:301-3. [PMID: 22141575 DOI: 10.1111/j.1538-7836.2011.04580.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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107
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Makita N, Seki A, Sumitomo N, Chkourko H, Fukuhara S, Watanabe H, Shimizu W, Bezzina CR, Hasdemir C, Mugishima H, Makiyama T, Baruteau A, Baron E, Horie M, Hagiwara N, Wilde AAM, Probst V, Le Marec H, Roden DM, Mochizuki N, Schott JJ, Delmar M. A connexin40 mutation associated with a malignant variant of progressive familial heart block type I. Circ Arrhythm Electrophysiol 2012; 5:163-72. [PMID: 22247482 PMCID: PMC4274644 DOI: 10.1161/circep.111.967604] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Progressive familial heart block type I (PFHBI) is a hereditary arrhythmia characterized by progressive conduction disturbances in the His-Purkinje system. PFHBI has been linked to genes such as SCN5A that influence cardiac excitability but not to genes that influence cell-to-cell communication. Our goal was to explore whether nucleotide substitutions in genes coding for connexin proteins would associate with clinical cases of PFHBI and if so, to establish a genotype-cell phenotype correlation for that mutation. METHODS AND RESULTS We screened 156 probands with PFHBI. In addition to 12 sodium channel mutations, we found a germ line GJA5 (connexin40 [Cx40]) mutation (Q58L) in 1 family. Heterologous expression of Cx40-Q58L in connexin-deficient neuroblastoma cells resulted in marked reduction of junctional conductance (Cx40-wild type [WT], 22.2±1.7 nS, n=14; Cx40-Q58L, 0.56±0.34 nS, n=14; P<0.001) and diffuse localization of immunoreactive proteins in the vicinity of the plasma membrane without formation of gap junctions. Heteromeric cotransfection of Cx40-WT and Cx40-Q58L resulted in homogenous distribution of proteins in the plasma membrane rather than in membrane plaques in ≈50% of cells; well-defined gap junctions were observed in other cells. Junctional conductance values correlated with the distribution of gap junction plaques. CONCLUSIONS Mutation Cx40-Q58L impairs gap junction formation at cell-cell interfaces. This is the first demonstration of a germ line mutation in a connexin gene that associates with inherited ventricular arrhythmias and emphasizes the importance of Cx40 in normal propagation in the specialized conduction system.
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Affiliation(s)
- Naomasa Makita
- Department of Molecular Pathophysiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
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108
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Igarashi T, Finet JE, Takeuchi A, Fujino Y, Strom M, Greener ID, Rosenbaum DS, Donahue JK. Connexin gene transfer preserves conduction velocity and prevents atrial fibrillation. Circulation 2012; 125:216-25. [PMID: 22158756 PMCID: PMC3260348 DOI: 10.1161/circulationaha.111.053272] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Several lines of evidence have suggested that maintenance of atrial fibrillation (AF) depends on reentrant mechanisms. Maintenance of reentry necessitates a sufficiently short refractory period and/or delayed conduction, and AF has been associated with both alterations. Fibrosis, cellular dysfunction, and gap junction protein alterations occur in AF and cause conduction delay. We performed this study to test the hypothesis that gap junction protein overexpression would improve conduction and prevent AF. METHODS AND RESULTS Thirty Yorkshire swine were randomized into 2 groups (sinus rhythm and AF), and each group into 3 subgroups: sham-operated control, gene therapy with adenovirus expressing connexin (Cx) 40, and gene therapy with adenovirus expressing Cx43 (n=5 per subgroup). All animals had epicardial gene painting; the AF group had burst atrial pacing. All animals underwent terminal study 7 days after gene transfer. Sinus rhythm animals had strong transgene expression but no atrial conduction changes. In AF animals, controls had reduced and lateralized Cx43 expression, and Cx43 gene transfer restored expression and cellular location to sinus rhythm control levels. In the AF group, both Cx40 and Cx43 gene transfer improved conduction and reduced AF relative to controls. CONCLUSIONS Connexin gene therapy preserved atrial conduction and prevented AF.
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Affiliation(s)
- Tomonori Igarashi
- Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio, USA
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109
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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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110
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Perrin MJ, Gollob MH. The role of atrial natriuretic peptide in modulating cardiac electrophysiology. Heart Rhythm 2011; 9:610-5. [PMID: 22083030 DOI: 10.1016/j.hrthm.2011.11.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Indexed: 11/29/2022]
Abstract
Since the discovery of atrial natriuretic peptide (ANP) in 1981, significant progress has been made in understanding the mechanism of its release and its role in salt and water balance in the body. It has also become clear that ANP plays a key role in cardiac electrophysiology, modulating the autonomic nervous system and regulating the function of cardiac ion channels. The clinical importance of this role was established when mutations in NPPA, the gene encoding ANP, were identified as a cause of familial atrial fibrillation. This review examines our current understanding of the electrophysiological effects of ANP, and their physiological relationship to clinical studies linking ANP and atrial fibrillation.
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Affiliation(s)
- Mark J Perrin
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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111
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Xiao J, Liang D, Chen YH. The genetics of atrial fibrillation: from the bench to the bedside. Annu Rev Genomics Hum Genet 2011; 12:73-96. [PMID: 21682648 DOI: 10.1146/annurev-genom-082410-101515] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Atrial fibrillation (AF) has become a growing global epidemic and a financial burden for society. The past 10 years have seen significant advances in our understanding of the genetic aspects of AF: At least 2 chromosomal loci and 17 causal genes have been identified in familial AF, and an additional 7 common variants and single-nucleotide polymorphisms in 11 different genes have been indicated in nonfamilial AF. However, the current management strategies for AF are suboptimal. The integration of genetic information into clinical practice may aid the early identification of AF patients who are at risk as well as the characterization of molecular pathways that culminate in AF, with the eventual result of better treatment. Never before has such an opportunity arisen to advance our understanding of the biology of AF through the translation of genetics findings from the bench to the bedside.
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Affiliation(s)
- Junjie Xiao
- Key Laboratory of Arrhythmias, Ministry of Education, and Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.
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112
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Affiliation(s)
- André G Kléber
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 022215, USA.
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113
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Xiao P, Gao C, Fan J, Du H, Long Y, Yin Y. Blockade of angiotensin II improves hyperthyroid induced abnormal atrial electrophysiological properties. ACTA ACUST UNITED AC 2011; 169:31-8. [DOI: 10.1016/j.regpep.2011.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Revised: 03/21/2011] [Accepted: 04/16/2011] [Indexed: 11/30/2022]
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114
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Bikou O, Thomas D, Trappe K, Lugenbiel P, Kelemen K, Koch M, Soucek R, Voss F, Becker R, Katus HA, Bauer A. Connexin 43 gene therapy prevents persistent atrial fibrillation in a porcine model. Cardiovasc Res 2011; 92:218-25. [DOI: 10.1093/cvr/cvr209] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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115
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Lemmens R, Hermans S, Nuyens D, Thijs V. Genetics of atrial fibrillation and possible implications for ischemic stroke. Stroke Res Treat 2011; 2011:208694. [PMID: 21822468 PMCID: PMC3148589 DOI: 10.4061/2011/208694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 05/25/2011] [Accepted: 05/31/2011] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation is the most common cardiac arrhythmia mainly caused by valvular, ischemic, hypertensive, and myopathic heart disease. Atrial fibrillation can occur in families suggesting a genetic background especially in younger subjects. Additionally recent studies have identified common genetic variants to be associated with atrial fibrillation in the general population. This cardiac arrhythmia has important public health implications because of its main complications: congestive heart failure and ischemic stroke. Since atrial fibrillation can result in ischemic stroke, one might assume that genetic determinants of this cardiac arrhythmia are also implicated in cerebrovascular disease. Ischemic stroke is a multifactorial, complex disease where multiple environmental and genetic factors interact. Whether genetic variants associated with a risk factor for ischemic stroke also increase the risk of a particular vascular endpoint still needs to be confirmed in many cases. Here we review the current knowledge on the genetic background of atrial fibrillation and the consequences for cerebrovascular disease.
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Affiliation(s)
- Robin Lemmens
- Department of Neurology and Laboratory for Neurobiology, Section of Experimental Neurology, School of Medicine, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
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116
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Liu X, Wang F, Knight AC, Zhao J, Xiao J. Common variants for atrial fibrillation: results from genome-wide association studies. Hum Genet 2011; 131:33-9. [DOI: 10.1007/s00439-011-1052-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 06/20/2011] [Indexed: 12/19/2022]
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117
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Yang YQ, Wang MY, Zhang XL, Tan HW, Shi HF, Jiang WF, Wang XH, Fang WY, Liu X. GATA4 loss-of-function mutations in familial atrial fibrillation. Clin Chim Acta 2011; 412:1825-30. [PMID: 21708142 DOI: 10.1016/j.cca.2011.06.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Revised: 06/10/2011] [Accepted: 06/11/2011] [Indexed: 12/13/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a major source of the substantially increased morbidity and mortality. Growing studies demonstrate that genetic defects play pivotal roles in a subgroup of AF. However, AF is a genetically heterogeneous disorder and the molecular basis of AF in a majority of cases remains unknown. METHODS The whole coding region of the GATA4 gene, which encodes a zinc-finger transcription factor essential for cardiogenesis, was analyzed in 130 unrelated probands with AF in contrast to 200 unrelated ethnically matched healthy individuals used as controls. The available family members of the probands harboring the identified mutations were genotyped. The functional effect of the mutant GATA4 was characterized using a luciferase reporter assay system. RESULTS Two novel heterozygous GATA4 mutations, p.S70T and p.S160T, were identified in 2 unrelated families with AF inherited as an autosomal dominant trait, respectively, which co-segregated with AF in each family with complete penetrance. Functional analysis showed that the mutations of GATA4 were associated with a significantly decreased transcriptional activity. CONCLUSION The findings provide new insight into the molecular mechanism involved in the pathogenesis of AF, suggesting the potential implications in the genetic diagnosis and gene-specific therapy of this common arrhythmia.
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Affiliation(s)
- Yi-Qing Yang
- Department of Cardiovascular Research, Shanghai Chest Hospital, Medical College of Shanghai Jiaotong University, PR China.
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118
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Investigation of somatic NKX2-5, GATA4 and HAND1 mutations in patients with tetralogy of Fallot. Pathology 2011; 43:322-6. [DOI: 10.1097/pat.0b013e32834635a9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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119
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Tuomi JM, Tyml K, Jones DL. Atrial tachycardia/fibrillation in the connexin 43 G60S mutant (Oculodentodigital dysplasia) mouse. Am J Physiol Heart Circ Physiol 2011; 300:H1402-11. [PMID: 21239638 DOI: 10.1152/ajpheart.01094.2010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Atrial fibrillation (AF), the most common cardiac arrhythmia seen in general practice, can be promoted by conduction slowing. Cardiac impulse conduction depends on gap junction channels, which are composed of connexins (Cxs). While atrial Cx40 and Cx43 are equally expressed, AF studies have primarily focused on Cx40 reductions. The G60S Cx43 mutant (Cx43(G60S/+)) mouse model of Oculodentodigital dysplasia has a 60% reduction in Cx43 in the atria. Cx43(G60S/+) mice were compared with Cx40-deficient (Cx40(-/-)) mice to determine the role of Cxs in atrial tachycardia/fibrillation (AT/F). Intracardiac electrophysiological studies were done in 6-mo-old male C57BL/6 Cx43(G60S/+) mutant, littermate (Cx43(+/+)), Cx40(-/-), and C57BL/6 wild-type (WT) mice. AT/F induction used an extra stimulus during sinus rhythm, programmed electrical stimulation, or burst pacing (1-ms pulses, 50-Hz, 400-ms train) in the absence and presence of carbachol (CCh). Atrial effective refractory periods did not differ between strains. Cx43(G60S/+) mice were more susceptible to induction of sustained AT/F (duration >2 min, 9 of 12; maximum >35 min) compared with Cx43(+/+) mice (3 of 11; χ(2) = 5.24; P = 0.02). CCh enhanced sustained AT/F susceptibility in WT (from 1 of 12 without, to 7 of 10 with CCh; χ(2) = 8.98; P < 0.01) but not in Cx40(-/-) mice (1 of 13 without vs. 2 of 9 with CCh; χ(2) = 0.95; P = NS). The pattern of epicardial recordings during AT/F in Cx43(G60S/+) mice was left preceding right, with left atrial fractionated activation patterns consistent with clinical observations of AF. In conclusions, while Cx43(G60S/+) mice had severe AT/F, Cx40(-/-) mice were resistant to CCh-induced AT/F.
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Affiliation(s)
- Jari M Tuomi
- Department of Physiology and Pharmacology, University of Western Ontario, London, Canada
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