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Zhong Y, Tang K, Li H, Zhao D, Kou W, Xu S, Zhang J, Yang H, Li S, Guo R, Peng W, Xu Y. Rs4968309 in Myosin Light Chain 4 (MYL4) Associated With Atrial Fibrillation Onset and Predicts Clinical Outcomes After Catheter Ablation in Atrial Fibrillation Patients Without Structural Heart Disease. Circ J 2019; 83:1994-2001. [PMID: 31406021 DOI: 10.1253/circj.cj-19-0415] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common arrhythmia with serious complications and a high rate of recurrence after catheter ablation. Recently, mutation ofMYL4was reported as responsible for familial atrial cardiomyopathy and AF. This study aimed to determine the association between polymorphism inMYL4with the onset and recurrence of AF.Methods and Results:A total of 7 single-nucleotide polymorphisms were selected by linkage disequilibrium and genotyped in 510 consecutive AF patients and 192 controls without structural heart disease. A total of 246 AF patients who underwent cryoballoon ablation had a 1-year scheduled follow-up study for AF recurrence. C allele and CC genotype of rs4968309 and A allele of rs1515751were associated with AF onset both before and after adjustment of covariation (age, sex, hypertension, and diabetes). AF type and left atrial size were different among the genotypes of rs4968309. Moreover, CC genotype of rs4968309 increased susceptibly of AF recurrence after cryoballoon ablation. The prevalence of hypertension was associated with rs1515752, and left atrial size was associated with the genotype of rs2071438. CONCLUSIONS C allele and CC genotype of rs4968309 inMYL4were associated with AF onset and recurrence. Moreover, the A allele of rs1515751 had a significant association with AF onset. The polymorphisms ofMYL4can predict AF onset and prognosis after ablation in AF patients without structural heart disease.
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Affiliation(s)
- Yuan Zhong
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Kai Tang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Hailing Li
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Dongdong Zhao
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Wenxin Kou
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Shaojie Xu
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Jun Zhang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Haotian Yang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Shuang Li
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Rong Guo
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Wenhui Peng
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
| | - Yawei Xu
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine
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Yakubova A, Thorrez L, Svetlichnyy D, Zwarts L, Vulsteke V, Laenen G, Oosterlinck W, Moreau Y, Dehaspe L, Van Houdt J, Cortés-Calabuig Á, De Moor B, Callaerts P, Herijgers P. ACE-inhibition induces a cardioprotective transcriptional response in the metabolic syndrome heart. Sci Rep 2018; 8:16169. [PMID: 30385846 PMCID: PMC6212468 DOI: 10.1038/s41598-018-34547-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 10/17/2018] [Indexed: 12/20/2022] Open
Abstract
Cardiovascular disease associated with metabolic syndrome has a high prevalence, but the mechanistic basis of metabolic cardiomyopathy remains poorly understood. We characterised the cardiac transcriptome in a murine metabolic syndrome (MetS) model (LDLR−/−; ob/ob, DKO) relative to the healthy, control heart (C57BL/6, WT) and the transcriptional changes induced by ACE-inhibition in those hearts. RNA-Seq, differential gene expression and transcription factor analysis identified 288 genes differentially expressed between DKO and WT hearts implicating 72 pathways. Hallmarks of metabolic cardiomyopathy were increased activity in integrin-linked kinase signalling, Rho signalling, dendritic cell maturation, production of nitric oxide and reactive oxygen species in macrophages, atherosclerosis, LXR-RXR signalling, cardiac hypertrophy, and acute phase response pathways. ACE-inhibition had a limited effect on gene expression in WT (55 genes, 23 pathways), and a prominent effect in DKO hearts (1143 genes, 104 pathways). In DKO hearts, ACE-I appears to counteract some of the MetS-specific pathways, while also activating cardioprotective mechanisms. We conclude that MetS and control murine hearts have unique transcriptional profiles and exhibit a partially specific transcriptional response to ACE-inhibition.
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Affiliation(s)
- Aziza Yakubova
- Department of Cardiovascular Sciences, Research Unit of Cardiac Surgery, KU Leuven, Leuven, Belgium
| | - Lieven Thorrez
- Department of Development and Regeneration, Interdisciplinary Research Facility, KU Leuven, Campus Kulak Kortrijk, Kortrijk, Belgium
| | - Dmitry Svetlichnyy
- Department of Human Genetics, Laboratory of Computational Biology, KU Leuven, Leuven, Belgium
| | - Liesbeth Zwarts
- Department of Human Genetics, Laboratory of Behavioral and Developmental Genetics, KU Leuven, Leuven, Belgium
| | - Veerle Vulsteke
- Department of Human Genetics, Laboratory of Behavioral and Developmental Genetics, KU Leuven, Leuven, Belgium
| | - Griet Laenen
- Department of Electrical Engineering, ESAT - STADIUS, Stadius Centre for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Leuven, Belgium
| | - Wouter Oosterlinck
- Department of Cardiovascular Sciences, Research Unit of Cardiac Surgery, KU Leuven, Leuven, Belgium
| | - Yves Moreau
- Department of Electrical Engineering, ESAT - STADIUS, Stadius Centre for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Leuven, Belgium
| | - Luc Dehaspe
- Department of Human Genetics, Genomics Core, Center for Human Genetics, University Hospital, KU Leuven, Leuven, Belgium
| | - Jeroen Van Houdt
- Department of Human Genetics, Genomics Core, Center for Human Genetics, University Hospital, KU Leuven, Leuven, Belgium
| | - Álvaro Cortés-Calabuig
- Department of Human Genetics, Genomics Core, Center for Human Genetics, University Hospital, KU Leuven, Leuven, Belgium
| | - Bart De Moor
- Department of Electrical Engineering, ESAT - STADIUS, Stadius Centre for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Leuven, Belgium
| | - Patrick Callaerts
- Department of Human Genetics, Laboratory of Behavioral and Developmental Genetics, KU Leuven, Leuven, Belgium.
| | - Paul Herijgers
- Department of Cardiovascular Sciences, Research Unit of Cardiac Surgery, KU Leuven, Leuven, Belgium.
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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17β-Estradiol-induced interaction of estrogen receptor α and human atrial essential myosin light chain modulates cardiac contractile function. Basic Res Cardiol 2016; 112:1. [DOI: 10.1007/s00395-016-0590-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/02/2016] [Indexed: 11/29/2022]
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Gudbjartsson DF, Holm H, Sulem P, Masson G, Oddsson A, Magnusson OT, Saemundsdottir J, Helgadottir HT, Helgason H, Johannsdottir H, Gretarsdottir S, Gudjonsson SA, Njølstad I, Løchen ML, Baum L, Ma RCW, Sigfusson G, Kong A, Thorgeirsson G, Sverrisson JT, Thorsteinsdottir U, Stefansson K, Arnar DO. A frameshift deletion in the sarcomere gene MYL4 causes early-onset familial atrial fibrillation. Eur Heart J 2016; 38:27-34. [PMID: 27742809 DOI: 10.1093/eurheartj/ehw379] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 06/04/2016] [Accepted: 08/09/2016] [Indexed: 11/13/2022] Open
Abstract
AIMS Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in man, causing substantial morbidity and mortality with a major worldwide public health impact. It is increasingly recognized as a highly heritable condition. This study aimed to determine genetic risk factors for early-onset AF. METHODS AND RESULTS We sequenced the whole genomes of 8453 Icelanders and imputed genotypes of the 25.5 million sequence variants we discovered into 1799 Icelanders with early-onset AF (diagnosed before 60 years of age) and 337 453 controls. Each sequence variant was tested for association based on multiplicative and recessive inheritance models. We discovered a rare frameshift deletion in the myosin MYL4 gene (c.234delC) that associates with early-onset AF under a recessive mode of inheritance (allelic frequency = 0.58%). We found eight homozygous carriers of the mutation, all of whom had early-onset AF. Six of the homozygotes were diagnosed by the age of 30 and the remaining two in their 50s. Three of the homozygotes had received pacemaker implantations due to sick sinus syndrome, three had suffered an ischemic stroke, and one suffered sudden cardiac death. CONCLUSIONS Through a population approach we found a loss of function mutation in the myosin gene MYL4 that, in the homozygous state, is completely penetrant for early-onset AF. The finding may provide novel mechanistic insight into the pathophysiology of this complex arrhythmia.
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Affiliation(s)
- Daniel F Gudbjartsson
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland .,School of Engineering and Natural Sciences, University of Iceland, Hjardarhaga 4, 107 Reykjavik, Iceland
| | - Hilma Holm
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland.,Department of Medicine, Landspitali- The National University Hospital, Hringbraut, 101 Reykjavik, Iceland
| | - Patrick Sulem
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland
| | - Gisli Masson
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland
| | | | | | | | | | | | | | | | | | - Inger Njølstad
- Institute of Community Medicine, University of Tromsø, Postboks 6050, Langnes, 9037 Tromsø, Norway
| | - Maja-Lisa Løchen
- Institute of Community Medicine, University of Tromsø, Postboks 6050, Langnes, 9037 Tromsø, Norway.,Department of Cardiology, University Hospital of North Norway, Sykehusvegen 38, 9019 Tromsø, Norway
| | - Larry Baum
- School of Pharmacy, Chinese University of Hong Kong, Hong Kong
| | - Ronald C W Ma
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Prince of Wales Hospital, 30 Ngan Shing Street, Sha Tin 999077 Hong Kong
| | - Gunnlaugur Sigfusson
- Children's Hospital, Landspitali- The National University Hospital, Hringbraut 101 Reykjavik, Iceland
| | - Augustine Kong
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland.,School of Engineering and Natural Sciences, University of Iceland, Hjardarhaga 4, 107 Reykjavik, Iceland
| | - Guðmundur Thorgeirsson
- Department of Medicine, Landspitali- The National University Hospital, Hringbraut, 101 Reykjavik, Iceland.,Faculty of Medicine, University of Iceland, Vatnsmyrarvegi 16, 101 Reykjavik, Iceland
| | - Jon Th Sverrisson
- Department of Internal Medicine, Akureyri Hospital, Eyrarlandsvegur, 600 Akureyri, Iceland
| | - Unnur Thorsteinsdottir
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland.,Faculty of Medicine, University of Iceland, Vatnsmyrarvegi 16, 101 Reykjavik, Iceland
| | - Kari Stefansson
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland.,Faculty of Medicine, University of Iceland, Vatnsmyrarvegi 16, 101 Reykjavik, Iceland
| | - David O Arnar
- deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland .,Department of Medicine, Landspitali- The National University Hospital, Hringbraut, 101 Reykjavik, Iceland.,Faculty of Medicine, University of Iceland, Vatnsmyrarvegi 16, 101 Reykjavik, Iceland
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Protective effects of endothelin receptor A and B inhibitors against doxorubicin-induced cardiomyopathy. Biochem Pharmacol 2015; 94:109-29. [PMID: 25660617 DOI: 10.1016/j.bcp.2015.01.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 01/27/2015] [Accepted: 01/27/2015] [Indexed: 11/21/2022]
Abstract
The clinical efficiency of the highly potent antitumor agent doxorubicin is limited by cardiotoxic effects. In a murine doxorubicin cardiotoxicity model, increased endothelin-1 (ET-1) expression and cardioprotective effects of the dual ET-1 blocker bosentan were demonstrated. To date it is unclear if combined blocking of endothelin A/B receptors is necessary or whether selective inhibition of one of the ET-1 receptors is sufficient for the observed cardioprotection. Therefore, we investigated the impact of dual (bosentan) and single endothelin receptor antagonism through sitaxentan (receptor A blocker) or BQ788 (receptor B blocker) in a murine doxorubicin cardiotoxicity model (C57BL/6N). Simultaneous administration of each endothelin receptor antagonist (ERA) with doxorubicin resulted in a significantly improved hemodynamic performance in comparison to the impaired cardiac function in control mice with bosentan being most effective but closely followed by sitaxentan and also BQ788. This cardioprotection was not caused by diminished doxorubicin levels in heart since the doxorubicin content in cardiac tissue was not altered by ERAs significantly. However, whole transcript expression profiling showed partly different effects of the ERAs on doxorubicin-modulated cardiac gene expression of genes involved in signal transduction (e.g. Stat3, Pim1, Akt1, Plcb2), fibrosis (e.g. Myl4), energy production (e.g. Ant1) or oxidative stress (e.g. Aox1). Furthermore, doxorubicin-mediated gene regulations were verified in the murine cardiomyocyte model HL-1 showing partly reversed expression patterns after co-administration of the ERAs. In summary, our results demonstrate strong cardioprotective effects of blocking ET-1 receptors against the doxorubicin-related cardiomyopathy and provide evidence to potential underlying signaling pathways.
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Artificial neural network inference (ANNI): a study on gene-gene interaction for biomarkers in childhood sarcomas. PLoS One 2014; 9:e102483. [PMID: 25025207 PMCID: PMC4099183 DOI: 10.1371/journal.pone.0102483] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 06/19/2014] [Indexed: 01/31/2023] Open
Abstract
Objective To model the potential interaction between previously identified biomarkers in children sarcomas using artificial neural network inference (ANNI). Method To concisely demonstrate the biological interactions between correlated genes in an interaction network map, only 2 types of sarcomas in the children small round blue cell tumors (SRBCTs) dataset are discussed in this paper. A backpropagation neural network was used to model the potential interaction between genes. The prediction weights and signal directions were used to model the strengths of the interaction signals and the direction of the interaction link between genes. The ANN model was validated using Monte Carlo cross-validation to minimize the risk of over-fitting and to optimize generalization ability of the model. Results Strong connection links on certain genes (TNNT1 and FNDC5 in rhabdomyosarcoma (RMS); FCGRT and OLFM1 in Ewing’s sarcoma (EWS)) suggested their potency as central hubs in the interconnection of genes with different functionalities. The results showed that the RMS patients in this dataset are likely to be congenital and at low risk of cardiomyopathy development. The EWS patients are likely to be complicated by EWS-FLI fusion and deficiency in various signaling pathways, including Wnt, Fas/Rho and intracellular oxygen. Conclusions The ANN network inference approach and the examination of identified genes in the published literature within the context of the disease highlights the substantial influence of certain genes in sarcomas.
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Jarosch R. The different muscle-energetics during shortening and stretch. Int J Mol Sci 2011; 12:2891-900. [PMID: 21686156 PMCID: PMC3116162 DOI: 10.3390/ijms12052891] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 03/17/2011] [Accepted: 04/12/2011] [Indexed: 11/16/2022] Open
Abstract
The helical shape of the thin filaments causes their passive counterclockwise rotation during muscle stretch that increases tensile stress and torque at first by unwinding and then by winding up the four anchoring Z-filaments. This means storage of energy in the series elastic Z-filaments and a considerable decrease of the liberated energy of heat and work to (h-w(ap)), where h is the heat energy and w(ap) the stretch energy induced from outside by an apparatus. The steep thin filament helix with an inclination angle of 70° promotes the passive rotation during stretch, but impedes the smooth sliding of shortening by increased friction and production of frictional heat. The frictional heat may be produced by the contact with the myosin cross-bridges: (1) when they passively snap on drilling thin filaments from cleft to cleft over a distance 2 × 2.7 nm = 5.4 nm between the globular actin monomers in one groove, causing stepwise motion; or (2) when they passively cycle from one helical groove to the next (distance 36 nm). The latter causes more heat and may take place on rotating thin filaments without an effective forward drilling ("idle rotation"), e.g., when they produce "unexplained heat" at the beginning of an isometric tetanus. In an Appendix to this paper the different states of muscle are defined. The function of its most important components is described and rotation model and power-stroke model of muscular contraction is compared.
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Affiliation(s)
- Robert Jarosch
- Formerly Institute of Plant Physiology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria; E-Mail: ; Tel.: +43-07612-67972
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Petzhold D, Lossie J, Keller S, Werner S, Haase H, Morano I. Human essential myosin light chain isoforms revealed distinct myosin binding, sarcomeric sorting, and inotropic activity. Cardiovasc Res 2011; 90:513-20. [PMID: 21262909 DOI: 10.1093/cvr/cvr026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS In this paper, we tested the hypothesis that different binding affinities of the C-terminus of human cardiac alkali (essential) myosin light chain (A1) isoforms to the IQ1 motif of the myosin lever arm provide a molecular basis for distinct sarcomeric sorting and inotropic activity. METHODS AND RESULTS We employed circular dichroism and surface plasmon resonance spectroscopy to investigate structural properties, secondary structures, and protein-protein interactions of a recombinant head-rod fragments of rat cardiac β-myosin heavy chain aa664-915 with alanine-mutated IQ2 domain (rβ-MYH(664-915)IQ(ala4)) and A1 isoforms [human atrial (hALC1) and human ventricular (hVLC-1) light chains]. Double epitope-tagging competition was used to monitor the intracellular localization of exogenously introduced hALC-1 and hVLC-1 constructs in neonatal rat cardiomyocytes. Contractile functions of A1 isoforms were investigated by monitoring shortening and intracellular-free Ca(2+) (Fura-2) of adult rat cardiomyocytes infected with adenoviral (Ad) vectors using hALC-1 or β-galactosidase as expression cassettes. hALC-1 bound more strongly (greater than three-fold lower K(D)) to rβ-MYH(664-915) than did hVLC-1. Sorting specificity of A1 isoforms to sarcomeres of cardiomyocytes rose in the order hVLC-1 to hALC-1. Replacement of endogenous VLC-1 by hALC-1 in adult rat cardiomyocytes increased contractility while the systolic Ca(2+) signal remained unchanged. CONCLUSION Intense myosin binding of hALC-1 provides a mechanism for preferential sarcomeric sorting and Ca(2+)-independent positive inotropic activity.
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Affiliation(s)
- Daria Petzhold
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
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Rodriguez A, Hilvo M, Kytömäki L, Fleming RE, Britton RS, Bacon BR, Parkkila S. Effects of iron loading on muscle: genome-wide mRNA expression profiling in the mouse. BMC Genomics 2007; 8:379. [PMID: 17949489 PMCID: PMC2151772 DOI: 10.1186/1471-2164-8-379] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 10/19/2007] [Indexed: 01/03/2023] Open
Abstract
Background Hereditary hemochromatosis (HH) encompasses genetic disorders of iron overload characterized by deficient expression or function of the iron-regulatory hormone hepcidin. Mutations in 5 genes have been linked to this disease: HFE, TFR2 (encoding transferrin receptor 2), HAMP (encoding hepcidin), SLC40A1 (encoding ferroportin) and HJV (encoding hemojuvelin). Hepcidin inhibits iron export from cells into plasma. Hemojuvelin, an upstream regulator of hepcidin expression, is expressed in mice mainly in the heart and skeletal muscle. It has been suggested that soluble hemojuvelin shed by the muscle might reach the liver to influence hepcidin expression. Heart muscle is one of the target tissues affected by iron overload, with resultant cardiomyopathy in some HH patients. Therefore, we investigated the effect of iron overload on gene expression in skeletal muscle and heart using Illumina™ arrays containing over 47,000 probes. The most apparent changes in gene expression were confirmed using real-time RT-PCR. Results Genes with up-regulated expression after iron overload in both skeletal and heart muscle included angiopoietin-like 4, pyruvate dehydrogenase kinase 4 and calgranulin A and B. The expression of transferrin receptor, heat shock protein 1B and DnaJ homolog B1 were down-regulated by iron in both muscle types. Two potential hepcidin regulatory genes, hemojuvelin and neogenin, showed no clear change in expression after iron overload. Conclusion Microarray analysis revealed iron-induced changes in the expression of several genes involved in the regulation of glucose and lipid metabolism, transcription and cellular stress responses. These may represent novel connections between iron overload and pathological manifestations of HH such as cardiomyopathy and diabetes.
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Affiliation(s)
- Alejandra Rodriguez
- Institute of Medical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland.
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Hernandez OM, Jones M, Guzman G, Szczesna-Cordary D. Myosin essential light chain in health and disease. Am J Physiol Heart Circ Physiol 2006; 292:H1643-54. [PMID: 17142342 DOI: 10.1152/ajpheart.00931.2006] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The essential light chain of myosin (ELC) is known to be important for structural stability of the alpha-helical lever arm domain of the myosin head, but its function in striated muscle contraction is poorly understood. Two ELC isoforms are expressed in fast skeletal muscle, a long isoform and its NH(2)-terminal approximately 40 amino acid shorter counterpart, whereas only the long ELC is observed in the heart. Biochemical and structural studies revealed that the NH(2)-terminus of the long ELC can make direct contacts with actin, but the effects of the ELC on the affinity of myosin for actin, ATPase, force, and the kinetics of force generating myosin cross-bridges are inconclusive. Myosin containing the long ELC has been shown to have slower cross-bridge kinetics than myosin with the short isoform. A difference was also reported among myosins with long isoforms. Increased shortening velocity was observed in atrial compared with ventricular muscle fibers. The common findings suggest that ELC provides the fine tuning of the myosin motor function, which is regulated in an isoform and tissue-dependent manner. The functional importance of the ELC is further implicated by the discovery of ELC mutations associated with Familial Hypertrophic Cardiomyopathy. The pathological phenotypes vary in severity, but more notably, almost all ELC mutations result in sudden cardiac death at a young age. This review summarizes the functional roles of striated muscle ELC in normal healthy muscle and in disease. Transgenic animal models and phenotypic characterization of ELC-mediated remodeling of the heart are also discussed.
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Affiliation(s)
- Olga M Hernandez
- Department of Molecular and Cellular Pharmacology, University of Miami, Leonard M. Miller School of Medicine, Miami Florida 33136, USA
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Andruchov O, Andruchova O, Galler S. Fine-tuning of cross-bridge kinetics in cardiac muscle of rat and mouse by myosin light chain isoforms. Pflugers Arch 2006; 452:667-73. [PMID: 16614852 DOI: 10.1007/s00424-006-0080-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 03/20/2006] [Indexed: 11/29/2022]
Abstract
Cross-bridge kinetics underlying stretch-induced force transients was studied in cardiac muscle strips with different myosin heavy chain (MHC) and myosin light chain (MLC) isoforms. The force transients were induced by stepwise stretches of maximally Ca(2+)-activated skinned muscle strips. The MHC and MLC isoforms were analyzed by electrophoreses after the mechanical experiments. Muscle strips of euthyroid rats and mice exclusively containing alpha-MHC were used. In addition, muscle strips of hyper- and hypothyroid rats containing different combinations of MHC and MLC isoforms were used. The thyroid hormone is known to alter the expression of MHC but not of MLC isoforms. In muscle strips containing exclusively alpha-MHC, atrial MLC isoforms (all atria of rats and mice) were associated with about 30% faster kinetics than ventricular MLC isoforms (ventricles of hyperthyroid rats and some muscle strips of ventricles of euthyroid rats and mice). On the other hand, in muscle strips containing exclusively ventricular MLC isoforms, alpha-MHC (ventricles of hyperthyroid rats) was associated with about 2.6 times faster kinetics than beta-MHC (ventricles of hypothyroid rats). We conclude that the MLC isoforms fine-tune cross-bridge kinetics, which underlies stretch-induced force transients, whereas the MHC isoforms mainly determine this kinetics. The effect of MLC isoforms on the cross-bridge kinetics may partially contribute to the faster twitch contraction in atria than in ventricles. Furthermore, it may play a role in various cardiomyopathies where atrial MLC isoforms are partially expressed in ventricles or ventricular MLC isoforms are partially expressed in atria.
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Affiliation(s)
- Oleg Andruchov
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
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