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D'Anatro A, Calvelo J, Feijóo M, Giorello FM. Differential expression analyses and detection of SNP loci associated with environmental variables: Are salinity and temperature factors involved in population differentiation and speciation in Odontesthes? COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2024; 52:101262. [PMID: 38861850 DOI: 10.1016/j.cbd.2024.101262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/13/2024]
Abstract
Environmental factors play a key role in individual adaptation to different local conditions. Because of this, studies about the physiological and genetic responses of individuals exposed to different natural environments offer clues about mechanisms involved in population differentiation, and as a subsequent result, speciation. Marine environments are especially suited to survey this kind of phenomena because they commonly harbor species adapted to different local conditions along a geographic continuum. Silversides belonging to Odontesthes are commonly distributed in tropical and temperate regions of South America and exhibit noticeable phenotypic plasticity, which allows them to adapt to contrasting environments. In this study, the genetic expression of O. argentinensis sampled along the Uruguayan Atlantic coast and estuarine adjacent areas was investigated. In addition, the correlation between individual genotypes and environmental variables was also analysed in O. argentinensis and O. bonariensis. Results obtained suggest a differential expression pattern of low magnitude among individuals from the different areas sampled and a correlation between several SNP loci and environmental variables. The analyses carried out did not show a clear differentiation among individuals sampled along different salinity regimens, but enriched GOTerms seem to be driven by water oxygen content. On the other hand, a total of 46 SNPs analysed in O. argentinensis and O. bonariensis showed a correlation with salinity and temperature. Although none of the correlated SNPs and corresponding genes from our both analyses were directly associated with hypoxia, genes related to the cardiovascular system and muscle cell differentiation were found. All these genes are interesting candidates for future studies since they are closely related to the differentially expressed genes. Although salinity was also mentioned as an important parameter limiting introgression between O. argentinensis and O. bonariensis, it was found that salinity does not drive differential expression in O. argentinensis, but rather oxygen levels. Moreover, salinity does not directly affect the structure and genetic divergence of the populations, they appear to be structured based on their degree of isolation and geographical distance between them. Further studies, like genome-wide analyses, could help to elucidate additional genes adapted to the different environments in these silverside species.
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Affiliation(s)
- Alejandro D'Anatro
- Laboratorio de Evolución y Sistemática, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay.
| | - Javier Calvelo
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Matías Feijóo
- Centro Universitario Regional Este, Sede Treinta y Tres, Universidad de la República, Treinta y Tres, Uruguay
| | - Facundo M Giorello
- Espacio de Biología Vegetal del Noreste, Centro Universitario de Tacuarembó, Universidad de la República, Tacuarembó, Uruguay
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Wang W, Li Y, Ko S, Feng N, Zhang M, Liu JJ, Zheng S, Ren B, Yu YP, Luo JH, Tseng GC, Liu S. IFDlong: an isoform and fusion detector for accurate annotation and quantification of long-read RNA-seq data. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.11.593690. [PMID: 38798496 PMCID: PMC11118288 DOI: 10.1101/2024.05.11.593690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Advancements in long-read transcriptome sequencing (long-RNA-seq) technology have revolutionized the study of isoform diversity. These full-length transcripts enhance the detection of various transcriptome structural variations, including novel isoforms, alternative splicing events, and fusion transcripts. By shifting the open reading frame or altering gene expressions, studies have proved that these transcript alterations can serve as crucial biomarkers for disease diagnosis and therapeutic targets. In this project, we proposed IFDlong, a bioinformatics and biostatistics tool to detect isoform and fusion transcripts using bulk or single-cell long-RNA-seq data. Specifically, the software performed gene and isoform annotation for each long-read, defined novel isoforms, quantified isoform expression by a novel expectation-maximization algorithm, and profiled the fusion transcripts. For evaluation, IFDlong pipeline achieved overall the best performance when compared with several existing tools in large-scale simulation studies. In both isoform and fusion transcript quantification, IFDlong is able to reach more than 0.8 Spearman's correlation with the truth, and more than 0.9 cosine similarity when distinguishing multiple alternative splicing events. In novel isoform simulation, IFDlong can successfully balance the sensitivity (higher than 90%) and specificity (higher than 90%). Furthermore, IFDlong has proved its accuracy and robustness in diverse in-house and public datasets on healthy tissues, cell lines and multiple types of diseases. Besides bulk long-RNA-seq, IFDlong pipeline has proved its compatibility to single-cell long-RNA-seq data. This new software may hold promise for significant impact on long-read transcriptome analysis. The IFDlong software is available at https://github.com/wenjiaking/IFDlong.
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Affiliation(s)
- Wenjia Wang
- Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA
| | - Yuzhen Li
- Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Sungjin Ko
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
| | - Ning Feng
- Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Manling Zhang
- Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Jia-Jun Liu
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
| | - Songyang Zheng
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
| | - Baoguo Ren
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
| | - Yan P. Yu
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
| | - Jian-Hua Luo
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
- Hillman Cancer Center, University of Pittsburgh Medical Center, Pittsburgh, PA
| | - George C. Tseng
- Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA
| | - Silvia Liu
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA
- Hillman Cancer Center, University of Pittsburgh Medical Center, Pittsburgh, PA
- Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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4
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Nefedova VV, Kopylova GV, Shchepkin DV, Kochurova AM, Kechko OI, Borzova VA, Ryabkova NS, Katrukha IA, Mitkevich VA, Bershitsky SY, Levitsky DI, Matyushenko AM. Impact of Troponin in Cardiomyopathy Development Caused by Mutations in Tropomyosin. Int J Mol Sci 2022; 23:ijms232415723. [PMID: 36555368 PMCID: PMC9779223 DOI: 10.3390/ijms232415723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/07/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
Tropomyosin (Tpm) mutations cause inherited cardiac diseases such as hypertrophic and dilated cardiomyopathies. We applied various approaches to investigate the role of cardiac troponin (Tn) and especially the troponin T (TnT) in the pathogenic effects of Tpm cardiomyopathy-associated mutations M8R, K15N, A277V, M281T, and I284V located in the overlap junction of neighboring Tpm dimers. Using co-sedimentation assay and viscosity measurements, we showed that TnT1 (fragment of TnT) stabilizes the overlap junction of Tpm WT and all Tpm mutants studied except Tpm M8R. However, isothermal titration calorimetry (ITC) indicated that TnT1 binds Tpm WT and all Tpm mutants similarly. By using ITC, we measured the direct KD of the Tpm overlap region, N-end, and C-end binding to TnT1. The ITC data revealed that the Tpm C-end binds to TnT1 independently from the N-end, while N-end does not bind. Therefore, we suppose that Tpm M8R binds to TnT1 without forming the overlap junction. We also demonstrated the possible role of Tn isoform composition in the cardiomyopathy development caused by M8R mutation. TnT1 dose-dependently reduced the velocity of F-actin-Tpm filaments containing Tpm WT, Tpm A277V, and Tpm M281T mutants in an in vitro motility assay. All mutations impaired the calcium regulation of the actin-myosin interaction. The M281T and I284V mutations increased the calcium sensitivity, while the K15N and A277V mutations reduced it. The Tpm M8R, M281T, and I284V mutations under-inhibited the velocity at low calcium concentrations. Our results demonstrate that Tpm mutations likely implement their pathogenic effects through Tpm interaction with Tn, cardiac myosin, or other protein partners.
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Affiliation(s)
- Victoria V. Nefedova
- Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
- Correspondence:
| | - Galina V. Kopylova
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Daniil V. Shchepkin
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Anastasia M. Kochurova
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Olga I. Kechko
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Russian Academy of Science, 119991 Moscow, Russia
| | - Vera A. Borzova
- Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Natalia S. Ryabkova
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- HyTest Ltd., 20520 Turku, Finland
| | - Ivan A. Katrukha
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- HyTest Ltd., 20520 Turku, Finland
| | - Vladimir A. Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Science, 119991 Moscow, Russia
| | - Sergey Y. Bershitsky
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Dmitrii I. Levitsky
- Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
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5
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Canty JM. Myocardial Injury, Troponin Release and Cardiomyocyte Death in Brief Ischemia, Failure and Ventricular Remodeling. Am J Physiol Heart Circ Physiol 2022; 323:H1-H15. [PMID: 35559722 DOI: 10.1152/ajpheart.00093.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Troponin released from irreversibly injured myocytes is the gold standard biomarker for the rapid identification of an acute coronary syndrome. In acute myocardial infarction, necrotic cell death is characterized by sarcolemmal disruption in response to a critical level of energy depletion after more than 15-minutes of ischemia. While troponin I and T are highly specific for cardiomyocyte death, high-sensitivity assays have demonstrated that measurable circulating levels of troponin are present in the majority of normal subjects. In addition, transient as well as chronic elevations have been demonstrated in many disease states not clearly associated with myocardial ischemia. The latter observations have given rise to the clinical concept of myocardial injury. This review will summarize evidence supporting the notion that circulating troponin levels parallel the extent of myocyte apoptosis in normal ventricular remodeling and in pathophysiological conditions not associated with infarction or necrosis. It will review the evidence that myocyte apoptosis can be accelerated by both diastolic strain from elevated ventricular preload as well as systolic strain from dyskinesis after brief episodes of ischemia too short to cause a critical level of myocyte energy depletion. We then show how chronic, low rates of myocyte apoptosis from endogenous myocyte turnover, repetitive ischemia or repetitive elevations in LV diastolic pressure can lead to significant myocyte loss in the absence of neurohormonal stimulation. Finally, we posit that the differential response to strain-induced injury in heart failure may determine whether progressive myocyte loss and HFrEF or interstitial fibrosis and HFpEF become the heart failure phenotype.
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Affiliation(s)
- John M Canty
- VA WNY Health Care System, the Departments of Medicine, Physiology & Biophysics, Biomedical Engineering and The Clinical and Translational Research Center of the University at Buffalo, Buffalo, NY, United States
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6
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Mahmud Z, Dhami PS, Rans C, Liu PB, Hwang PM. Dilated Cardiomyopathy Mutations and Phosphorylation disrupt the Active Orientation of Cardiac Troponin C. J Mol Biol 2021; 433:167010. [PMID: 33901537 DOI: 10.1016/j.jmb.2021.167010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/07/2021] [Accepted: 04/20/2021] [Indexed: 11/28/2022]
Abstract
Cardiac troponin (cTn) is made up of three subunits, cTnC, cTnI, and cTnT. The regulatory N-terminal domain of cTnC (cNTnC) controls cardiac muscle contraction in a calcium-dependent manner. We show that calcium-saturated cNTnC can adopt two different orientations, with the "active" orientation consistent with the 2020 cryo-EM structure of the activated cardiac thin filament by Yamada et al. Using solution NMR 15N R2 relaxation analysis, we demonstrate that the two domains of cTnC tumble independently (average R2 10 s-1), being connected by a flexible linker. However, upon addition of cTnI1-77, the complex tumbles as a rigid unit (R2 30 s-1). cTnI phosphomimetic mutants S22D/S23D, S41D/S43D and dilated cardiomyopathy- (DCM-)associated mutations cTnI K35Q, cTnC D75Y, and cTnC G159D destabilize the active orientation of cNTnC, with intermediate 15N R2 rates (R2 17-23 s-1). The active orientation of cNTnC is stabilized by the flexible tails of cTnI, cTnI1-37 and cTnI135-209. Surprisingly, when cTnC is incorporated into complexes lacking these tails (cTnC-cTnI38-134, cTnC-cTnT223-288, or cTnC-cTnI38-134-cTnT223-288), the cNTnC domain is still immobilized, revealing a new interaction between cNTnC and the IT-arm that stabilizes a "dormant" orientation. We propose that the calcium sensitivity of the cardiac troponin complex is regulated by an equilibrium between active and dormant orientations, which can be shifted through post-translational modifications or DCM-associated mutations.
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Affiliation(s)
- Zabed Mahmud
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Prabhpaul S Dhami
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Caleb Rans
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Philip B Liu
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Peter M Hwang
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada; Department of Medicine, University of Alberta, Edmonton, AB T6G 2R3, Canada.
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7
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Abstract
The cardiac troponin complex, composed of three regulatory proteins (cTnI, cTnT, TnC), functions as the critical regulator of cardiac muscle contraction and relaxation. Myofilament protein-protein interactions are regulated by post-translational modifications (PTMs) to the protein constituents of this complex. Dysregulation of troponin PTMs, particularly phosphorylation, results in altered cardiac contractility. Altered PTMs and isoforms have been increasingly recognized as the molecular mechanisms underlying heart diseases. Therefore, it is essential to comprehensively analyze cardiac troponin proteoforms that arise from PTMs, alternative splicing, and sequence variations. In this chapter, we described two detailed protocols for the enrichment and purification of endogenous cardiac troponin proteoforms from cardiac tissue. Subsequently, mass spectrometry (MS)-based top-down proteomics utilizing online liquid chromatography (LC)/quadrupole time-of-flight (Q-TOF) MS for separation, profiling, and quantification of the troponins was demonstrated. Characterization of troponin amino acid sequence and the localization of PTMs were shown using Fourier-transform ion cyclotron resonance (FT-ICR) MS with electron capture dissociation (ECD) and collisionally activated dissociation (CAD). Furthermore, we described the use of MASH software, a comprehensive and free software package developed in our lab, for top-down proteomics data analysis. The methods we described can be applied for the analysis of troponin proteoforms in cardiac tissues, from animal models to human clinical samples, for heart disease.
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8
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Marston S, Zamora JE. Troponin structure and function: a view of recent progress. J Muscle Res Cell Motil 2019; 41:71-89. [PMID: 31030382 PMCID: PMC7109197 DOI: 10.1007/s10974-019-09513-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 04/12/2019] [Indexed: 12/15/2022]
Abstract
The molecular mechanism by which Ca2+ binding and phosphorylation regulate muscle contraction through Troponin is not yet fully understood. Revealing the differences between the relaxed and active structure of cTn, as well as the conformational changes that follow phosphorylation has remained a challenge for structural biologists over the years. Here we review the current understanding of how Ca2+, phosphorylation and disease-causing mutations affect the structure and dynamics of troponin to regulate the thin filament based on electron microscopy, X-ray diffraction, NMR and molecular dynamics methodologies.
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Affiliation(s)
- Steven Marston
- NHLI and Chemistry Departments, Imperial College London, W12 0NN, London, UK.
| | - Juan Eiros Zamora
- NHLI and Chemistry Departments, Imperial College London, W12 0NN, London, UK
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In vitro analyses of suspected arrhythmogenic thin filament variants as a cause of sudden cardiac death in infants. Proc Natl Acad Sci U S A 2019; 116:6969-6974. [PMID: 30886088 DOI: 10.1073/pnas.1819023116] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Sudden unexpected death of an infant (SUDI) is a devastating occurrence for families. To investigate the genetic pathogenesis of SUDI, we sequenced >70 genes from 191 autopsy-negative SUDI victims. Ten infants sharing a previously unknown variant in troponin I (TnI) were identified. The mutation (TNNI1 R37C+/-) is in the fetal/neonatal paralog of TnI, a gene thought to be expressed in the heart up to the first 24 months of life. Using phylogenetic analysis and molecular dynamics simulations, it was determined that arginine at residue 37 in TNNI1 may play a critical functional role, suggesting that the variant may be pathogenic. We investigated the biophysical properties of the TNNI1 R37C mutation in human reconstituted thin filaments (RTFs) using fluorometry. RTFs reconstituted with the mutant R37C TnI exhibited reduced Ca2+-binding sensitivity due to an increased Ca2+ off-rate constant. Furthermore, we generated TNNI1 R37C+/- mutants in human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) using CRISPR-Cas9. In monolayers of hiPSC-CMs, we simultaneously monitored voltage and Ca2+ transients through optical mapping and compared them to their isogenic controls. We observed normal intrinsic beating patterns under control conditions in TNNI1 R37C+/- at stimulation frequencies of 55 beats/min (bpm), but these cells showed no restitution with increased stimulation frequency to 65 bpm and exhibited alternans at >75 bpm. The WT hiPSC-CMs did not exhibit any sign of arrhythmogenicity even at stimulation frequencies of 120 bpm. The approach used in this study provides critical physiological and mechanistic bases to investigate sarcomeric mutations in the pathogenesis of SUDI.
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10
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Visone R, Talò G, Lopa S, Rasponi M, Moretti M. Enhancing all-in-one bioreactors by combining interstitial perfusion, electrical stimulation, on-line monitoring and testing within a single chamber for cardiac constructs. Sci Rep 2018; 8:16944. [PMID: 30446711 PMCID: PMC6240103 DOI: 10.1038/s41598-018-35019-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 10/15/2018] [Indexed: 12/22/2022] Open
Abstract
Tissue engineering strategies have been extensively exploited to generate functional cardiac patches. To maintain cardiac functionality in vitro, bioreactors have been designed to provide perfusion and electrical stimulation, alone or combined. However, due to several design limitations the integration of optical systems to assess cardiac maturation level is still missing within these platforms. Here we present a bioreactor culture chamber that provides 3D cardiac constructs with a bidirectional interstitial perfusion and biomimetic electrical stimulation, allowing direct cellular optical monitoring and contractility test. The chamber design was optimized through finite element models to house an innovative scaffold anchoring system to hold and to release it for the evaluation of tissue maturation and functionality by contractility tests. Neonatal rat cardiac fibroblasts subjected to a combined perfusion and electrical stimulation showed positive cell viability over time. Neonatal rat cardiomyocytes were successfully monitored for the entire culture period to assess their functionality. The combination of perfusion and electrical stimulation enhanced patch maturation, as evidenced by the higher contractility, the enhanced beating properties and the increased level of cardiac protein expression. This new multifunctional bioreactor provides a relevant biomimetic environment allowing for independently culturing, real-time monitoring and testing up to 18 separated patches.
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Affiliation(s)
- Roberta Visone
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Giuseppe Talò
- Cell and Tissue Engineering Laboratory, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Silvia Lopa
- Cell and Tissue Engineering Laboratory, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Marco Rasponi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Matteo Moretti
- Cell and Tissue Engineering Laboratory, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy. .,Regenerative Medicine Technologies Lab, Ente Ospedaliero Cantonale (EOC), Lugano, Switzerland. .,Cardiocentro Ticino, Lugano, Switzerland.
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11
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The Molecular Mechanisms of Mutations in Actin and Myosin that Cause Inherited Myopathy. Int J Mol Sci 2018; 19:ijms19072020. [PMID: 29997361 PMCID: PMC6073311 DOI: 10.3390/ijms19072020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 07/06/2018] [Accepted: 07/08/2018] [Indexed: 12/23/2022] Open
Abstract
The discovery that mutations in myosin and actin genes, together with mutations in the other components of the muscle sarcomere, are responsible for a range of inherited muscle diseases (myopathies) has revolutionized the study of muscle, converting it from a subject of basic science to a relevant subject for clinical study and has been responsible for a great increase of interest in muscle studies. Myopathies are linked to mutations in five of the myosin heavy chain genes, three of the myosin light chain genes, and three of the actin genes. This review aims to determine to what extent we can explain disease phenotype from the mutant genotype. To optimise our chances of finding the right mechanism we must study a myopathy where there are a large number of different mutations that cause a common phenotype and so are likely to have a common mechanism: a corollary to this criterion is that if any mutation causes the disease phenotype but does not correspond to the proposed mechanism, then the whole mechanism is suspect. Using these criteria, we consider two cases where plausible genotype-phenotype mechanisms have been proposed: the actin “A-triad” and the myosin “mesa/IHD” models.
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12
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Li Y, Zhu G, Paolocci N, Zhang P, Takahashi C, Okumus N, Heravi A, Keceli G, Ramirez-Correa G, Kass DA, Murphy AM. Heart Failure-Related Hyperphosphorylation in the Cardiac Troponin I C Terminus Has Divergent Effects on Cardiac Function In Vivo. Circ Heart Fail 2017; 10:CIRCHEARTFAILURE.117.003850. [PMID: 28899987 PMCID: PMC5612410 DOI: 10.1161/circheartfailure.117.003850] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 08/02/2017] [Indexed: 01/14/2023]
Abstract
BACKGROUND In human heart failure, Ser199 (equivalent to Ser200 in mouse) of cTnI (cardiac troponin I) is significantly hyperphosphorylated, and in vitro studies suggest that it enhances myofilament calcium sensitivity and alters calpain-mediated cTnI proteolysis. However, how its hyperphosphorylation affects cardiac function in vivo remains unknown. METHODS AND RESULTS To address the question, 2 transgenic mouse models were generated: a phospho-mimetic cTnIS200D and a phospho-silenced cTnIS200A, each driven by the cardiomyocyte-specific α-myosin heavy chain promoter. Cardiac structure assessed by echocardiography and histology was normal in both transgenic models compared with littermate controls (n=5). Baseline in vivo hemodynamics and isolated muscle studies showed that cTnIS200D significantly prolonged relaxation and lowered left ventricular peak filling rate, whereas ejection fraction and force development were normal (n=5). However, with increased heart rate or β-adrenergic stimulation, cTnIS200D mice had less enhanced ejection fraction or force development versus controls, whereas relaxation improved similarly to controls (n=5). By contrast, cTnIS200A was functionally normal both at baseline and under the physiological stresses. To test whether either mutation impacted cardiac response to ischemic stress, isolated hearts were subjected to ischemia/reperfusion. cTnIS200D were protected, recovering 88±8% of contractile function versus 35±15% in littermate controls and 28±8% in cTnIS200A (n=5). This was associated with less cTnI proteolysis in cTnIS200D hearts. CONCLUSIONS Hyperphosphorylation of this serine in cTnI C terminus impacts heart function by depressing diastolic function at baseline and limiting systolic reserve under physiological stresses. However, paradoxically, it preserves heart function after ischemia/reperfusion injury, potentially by decreasing proteolysis of cTnI.
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Affiliation(s)
- Yuejin Li
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - Guangshuo Zhu
- Department of Medicine/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - Nazareno Paolocci
- Department of Medicine/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - Pingbo Zhang
- Deparment of Ophthalmology, Johns Hopkins University, Baltimore, MD
| | - Cyrus Takahashi
- Department of Medicine/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - Nazli Okumus
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University, Baltimore, MD,Istanbul Faculty of Medicine, Istanbul, Turkey
| | - Amir Heravi
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - Gizem Keceli
- Department of Medicine/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - Genaro Ramirez-Correa
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University, Baltimore, MD
| | - David A Kass
- Department of Medicine/Division of Cardiology, Johns Hopkins University, Baltimore, MD,Department of Pharmacology and Molecular Sciences, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | - Anne M Murphy
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University, Baltimore, MD
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13
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Li Y, Zeng Q, Liu G, Du J, Gao B, Wang W, Zheng Z, Hu S, Ji B. Development and Evaluation of Heartbeat: A Machine Perfusion Heart Preservation System. Artif Organs 2017; 41:E240-E250. [PMID: 28800676 DOI: 10.1111/aor.12867] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 08/18/2016] [Accepted: 08/26/2016] [Indexed: 12/11/2022]
Abstract
Static cold storage is accompanied with a partial safe ischemic interval for donor hearts. In this current study, a machine perfusion system was built to provide a better preservation for the donor heart and assessment for myocardial function. Chinese mini-swine (weight 30-35 kg, n = 16) were randomly divided into HTK, Celsior, and Heartbeat groups. All donor hearts were respectively preserved for 8 hours under static cold storage or machine perfusion. The perfusion solution is aimed to maintain its homeostasis based on monitoring the Heartbeat group. The ultrastructure of myocardium suggests better myocardial protection in the Heartbeat group compared with HTK or Celsior-preserved hearts. The myocardial and coronary artery structural and functional integrity was evaluated by immunofluorescence and Western blots in the Heartbeat. In the Heartbeat group, donor hearts maintained a high adenosine triphosphate level. Bcl-2 and Beclin-1 protein demonstrates high expression in the Celsior group. The Heartbeat system can be used to preserve donor hearts, and it could guarantee the myocardial and endothelial function of hearts during machine perfusion. Translating Heartbeat into clinical practice, it is such as to impact on donor heart preservation for cardiac transplantation.
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Affiliation(s)
- Yongnan Li
- Department of Cardiopulmonary Bypass, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China.,Department of Cardiac Surgery, Lanzhou University Second Hospital, Lanzhou, China
| | - Qingdong Zeng
- Department of Cardiopulmonary Bypass, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Gang Liu
- Department of Cardiopulmonary Bypass, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Junzhe Du
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Bingren Gao
- Department of Cardiac Surgery, Lanzhou University Second Hospital, Lanzhou, China
| | - Wei Wang
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Zhe Zheng
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Shengshou Hu
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Bingyang Ji
- Department of Cardiopulmonary Bypass, State Key Laboratory of Cardiovascular Medicine, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
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14
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Cai W, Tucholski TM, Gregorich ZR, Ge Y. Top-down Proteomics: Technology Advancements and Applications to Heart Diseases. Expert Rev Proteomics 2016; 13:717-30. [PMID: 27448560 DOI: 10.1080/14789450.2016.1209414] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Heart diseases are a leading cause of morbidity and mortality for both men and women worldwide, and impose significant economic burdens on the healthcare systems. Despite substantial effort over the last several decades, the molecular mechanisms underlying diseases of the heart remain poorly understood. AREAS COVERED Altered protein post-translational modifications (PTMs) and protein isoform switching are increasingly recognized as important disease mechanisms. Top-down high-resolution mass spectrometry (MS)-based proteomics has emerged as the most powerful method for the comprehensive analysis of PTMs and protein isoforms. Here, we will review recent technology developments in the field of top-down proteomics, as well as highlight recent studies utilizing top-down proteomics to decipher the cardiac proteome for the understanding of the molecular mechanisms underlying diseases of the heart. Expert commentary: Top-down proteomics is a premier method for the global and comprehensive study of protein isoforms and their PTMs, enabling the identification of novel protein isoforms and PTMs, characterization of sequence variations, and quantification of disease-associated alterations. Despite significant challenges, continuous development of top-down proteomics technology will greatly aid the dissection of the molecular mechanisms underlying diseases of the hearts for the identification of novel biomarkers and therapeutic targets.
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Affiliation(s)
- Wenxuan Cai
- a Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA.,b Molecular and Cellular Pharmacology Training Program , University of Wisconsin-Madison , Madison , WI , USA
| | - Trisha M Tucholski
- c Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA
| | - Zachery R Gregorich
- a Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA.,b Molecular and Cellular Pharmacology Training Program , University of Wisconsin-Madison , Madison , WI , USA
| | - Ying Ge
- a Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA.,c Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA.,d Human Proteomics Program , University of Wisconsin-Madison , Madison , WI , USA
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15
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Jin Y, Peng Y, Lin Z, Chen YC, Wei L, Hacker TA, Larsson L, Ge Y. Comprehensive analysis of tropomyosin isoforms in skeletal muscles by top-down proteomics. J Muscle Res Cell Motil 2016; 37:41-52. [PMID: 27090236 PMCID: PMC4955698 DOI: 10.1007/s10974-016-9443-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/07/2016] [Indexed: 01/09/2023]
Abstract
Mammalian skeletal muscles are heterogeneous in nature and are capable of performing various functions. Tropomyosin (Tpm) is a major component of the thin filament in skeletal muscles and plays an important role in controlling muscle contraction and relaxation. Tpm is known to consist of multiple isoforms resulting from different encoding genes and alternative splicing, along with post-translational modifications. However, a systematic characterization of Tpm isoforms in skeletal muscles is still lacking. Therefore, we employed top-down mass spectrometry (MS) to identify and characterize Tpm isoforms present in different skeletal muscles from multiple species, including swine, rat, and human. Our study revealed that Tpm1.1 and Tpm2.2 are the two major Tpm isoforms in swine and rat skeletal muscles, whereas Tpm1.1, Tpm2.2, and Tpm3.12 are present in human skeletal muscles. Tandem MS was utilized to identify the sequences of the major Tpm isoforms. Furthermore, quantitative analysis revealed muscle-type specific differences in the abundance of un-modified and modified Tpm isoforms in rat and human skeletal muscles. This study represents the first systematic investigation of Tpm isoforms in skeletal muscles, which not only demonstrates the capabilities of top-down MS for the comprehensive characterization of skeletal myofilament proteins but also provides the basis for further studies on these Tpm isoforms in muscle-related diseases.
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Affiliation(s)
- Yutong Jin
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA
| | - Ying Peng
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Ziqing Lin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Yi-Chen Chen
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA
| | - Liming Wei
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
- Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, P.R. China
| | - Timothy A Hacker
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Lars Larsson
- Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Clinical Neurophysiology Section, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
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16
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Fuller SJ, Osborne SA, Leonard SJ, Hardyman MA, Vaniotis G, Allen BG, Sugden PH, Clerk A. Cardiac protein kinases: the cardiomyocyte kinome and differential kinase expression in human failing hearts. Cardiovasc Res 2015; 108:87-98. [PMID: 26260799 DOI: 10.1093/cvr/cvv210] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 07/24/2015] [Indexed: 12/20/2022] Open
Abstract
AIMS Protein kinases are potential therapeutic targets for heart failure, but most studies of cardiac protein kinases derive from other systems, an approach that fails to account for specific kinases expressed in the heart and the contractile cardiomyocytes. We aimed to define the cardiomyocyte kinome (i.e. the protein kinases expressed in cardiomyocytes) and identify kinases with altered expression in human failing hearts. METHODS AND RESULTS Expression profiling (Affymetrix microarrays) detected >400 protein kinase mRNAs in rat neonatal ventricular myocytes (NVMs) and/or adult ventricular myocytes (AVMs), 32 and 93 of which were significantly up-regulated or down-regulated (greater than two-fold), respectively, in AVMs. Data for AGC family members were validated by qPCR. Proteomics analysis identified >180 cardiomyocyte protein kinases, with high relative expression of mitogen-activated protein kinase cascades and other known cardiomyocyte kinases (e.g. CAMKs, cAMP-dependent protein kinase). Other kinases are poorly investigated (e.g. Slk, Stk24, Oxsr1). Expression of Akt1/2/3, BRaf, ERK1/2, Map2k1, Map3k8, Map4k4, MST1/3, p38-MAPK, PKCδ, Pkn2, Ripk1/2, Tnni3k, and Zak was confirmed by immunoblotting. Relative to total protein, Map3k8 and Tnni3k were up-regulated in AVMs vs. NVMs. Microarray data for human hearts demonstrated variation in kinome expression that may influence responses to kinase inhibitor therapies. Furthermore, some kinases were up-regulated (e.g. NRK, JAK2, STK38L) or down-regulated (e.g. MAP2K1, IRAK1, STK40) in human failing hearts. CONCLUSION This characterization of the spectrum of kinases expressed in cardiomyocytes and the heart (cardiomyocyte and cardiac kinomes) identified novel kinases, some of which are differentially expressed in failing human hearts and could serve as potential therapeutic targets.
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Affiliation(s)
- Stephen J Fuller
- School of Biological Sciences, University of Reading, Whiteknights Campus, Reading, Berkshire RG6 6AS, UK
| | - Sally A Osborne
- School of Biological Sciences, University of Reading, Whiteknights Campus, Reading, Berkshire RG6 6AS, UK
| | - Sam J Leonard
- School of Biological Sciences, University of Reading, Whiteknights Campus, Reading, Berkshire RG6 6AS, UK
| | - Michelle A Hardyman
- School of Biological Sciences, University of Reading, Whiteknights Campus, Reading, Berkshire RG6 6AS, UK
| | - George Vaniotis
- Institut de Cardiologie de Montréal Centre de Recherche, Montréal, QC, Canada H1T 1C8 Département de Biochimie, Université de Montréal, Montréal, QC, Canada H3T 1J4
| | - Bruce G Allen
- Institut de Cardiologie de Montréal Centre de Recherche, Montréal, QC, Canada H1T 1C8 Département de Biochimie, Université de Montréal, Montréal, QC, Canada H3T 1J4 Département de Médecine, Université de Montréal, Montréal, QC, Canada H3T 1J4
| | - Peter H Sugden
- School of Biological Sciences, University of Reading, Whiteknights Campus, Reading, Berkshire RG6 6AS, UK
| | - Angela Clerk
- School of Biological Sciences, University of Reading, Whiteknights Campus, Reading, Berkshire RG6 6AS, UK
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17
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Schwan J, Campbell SG. Prospects for In Vitro Myofilament Maturation in Stem Cell-Derived Cardiac Myocytes. Biomark Insights 2015; 10:91-103. [PMID: 26085788 PMCID: PMC4463797 DOI: 10.4137/bmi.s23912] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/09/2015] [Accepted: 03/11/2015] [Indexed: 12/20/2022] Open
Abstract
Cardiomyocytes derived from human stem cells are quickly becoming mainstays of cardiac regenerative medicine, in vitro disease modeling, and drug screening. Their suitability for such roles may seem obvious, but assessments of their contractile behavior suggest that they have not achieved a completely mature cardiac muscle phenotype. This could be explained in part by an incomplete transition from fetal to adult myofilament protein isoform expression. In this commentary, we review evidence that supports this hypothesis and discuss prospects for ultimately generating engineered heart tissue specimens that behave similarly to adult human myocardium. We suggest approaches to better characterize myofilament maturation level in these in vitro systems, and illustrate how new computational models could be used to better understand complex relationships between muscle contraction, myofilament protein isoform expression, and maturation.
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Affiliation(s)
- Jonas Schwan
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
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18
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Kooij V, Venkatraman V, Kirk JA, Ubaida-Mohien C, Graham DR, Faber MJ, Van Eyk JE. Identification of cardiac myofilament protein isoforms using multiple mass spectrometry based approaches. Proteomics Clin Appl 2015; 8:578-589. [PMID: 24974818 DOI: 10.1002/prca.201400039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/30/2014] [Accepted: 06/24/2014] [Indexed: 02/01/2023]
Abstract
PURPOSE The identification of protein isoforms in complex biological samples is challenging. We, therefore, used an MS approach to unambiguously identify cardiac myofilament protein isoforms based on the observation of a tryptic peptide consisting of a sequence unique to a particular isoform. EXPERIMENTAL DESIGN Three different workflows were used to isolate and fractionate rat cardiac myofilament subproteomes. All fractions were analyzed on an LTQ-Orbitrap MS, proteins were identified using various search engines (MASCOT, X!Tandem, X!Tandem Kscore, and OMSSA) with results combined via PepArML Meta-Search engine, and a postsearch analysis was performed by MASPECTRAS. All MS data have been deposited in the ProteomeXchange with identifier PXD000874 (http://proteomecentral.proteomexchange.org/dataset/PXD000874). RESULTS The combination of multiple workflows and search engines resulted in a larger number of nonredundant proteins identified than with individual methods. A total of 102 myofilament annotated proteins were observed overlapping in two or three of the workflows. Literature search for myofilament presence with manual validation of the MS spectra was carried out for unambiguous identification: ten cardiac myofilament and 17 cardiac myofilament-associated proteins were identified with 39 isoforms and subisoforms. CONCLUSION AND CLINICAL RELEVANCE We have identified multiple isoforms of myofilament proteins that are present in cardiac tissue using unique tryptic peptides. Changes in distribution of these protein isoforms under pathological conditions could ultimately allow for clinical diagnostics or as therapeutic targets.
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Affiliation(s)
- Viola Kooij
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA
| | - Vidya Venkatraman
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA.,Advanced Clinical Biosystems Research Institute, Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, USA
| | - Jonathan A Kirk
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA
| | - Ceereena Ubaida-Mohien
- Department of Molecular and Comparative Pathobiology, The Johns Hopkins University, Baltimore, MD, USA
| | - David R Graham
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA.,Department of Molecular and Comparative Pathobiology, The Johns Hopkins University, Baltimore, MD, USA
| | - Matthijs J Faber
- Erasmus MC-Sophia, Department of Pediatrics, Division of Pediatric Cardiology, Rotterdam, The Netherlands
| | - Jennifer E Van Eyk
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA.,Advanced Clinical Biosystems Research Institute, Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, USA
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19
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Abstract
Troponin proteins in cooperative interaction with tropomyosin are responsible for controlling the contraction of the striated muscles in response to changes in the intracellular calcium concentration. Contractility of the muscle is determined by the constituent protein isoforms, and the isoforms can switch over from one form to another depending on physiological demands and pathological conditions. In Drosophila, amajority of themyofibrillar proteins in the indirect flight muscles (IFMs) undergo post-transcriptional and post-translational isoform changes during pupal to adult metamorphosis to meet the high energy and mechanical demands of flight. Using a newly generated Gal4 strain (UH3-Gal4) which is expressed exclusively in the IFMs, during later stages of development, we have looked at the developmental and functional importance of each of the troponin subunits (troponin-I, troponin-T and troponin-C) and their isoforms. We show that all the troponin subunits are required for normal myofibril assembly and flight, except for the troponin-C isoform 1 (TnC1). Moreover, rescue experiments conducted with troponin-I embryonic isoform in the IFMs, where flies were rendered flightless, show developmental and functional differences of TnI isoforms and importance of maintaining the right isoform.
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20
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Dissecting human skeletal muscle troponin proteoforms by top-down mass spectrometry. J Muscle Res Cell Motil 2015; 36:169-81. [PMID: 25613324 DOI: 10.1007/s10974-015-9404-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/07/2015] [Indexed: 01/26/2023]
Abstract
Skeletal muscles are the most abundant tissues in the human body. They are composed of a heterogeneous collection of muscle fibers that perform various functions. Skeletal muscle troponin (sTn) regulates skeletal muscle contraction and relaxation. sTn consists of 3 subunits, troponin I (TnI), troponin T (TnT), and troponin C (TnC). TnI inhibits the actomyosin Mg(2+)-ATPase, TnC binds Ca(2+), and TnT is the tropomyosin (Tm)-binding subunit. The cardiac and skeletal isoforms of Tn share many similarities but the roles of modifications of Tn in the two muscles may differ. The modifications of cardiac Tn are known to alter muscle contractility and have been well-characterized. However, the modification status of sTn remains unclear. Here, we have employed top-down mass spectrometry (MS) to decipher the modifications of human sTnT and sTnI. We have extensively characterized sTnT and sTnI proteoforms, including alternatively spliced isoforms and post-translationally modified forms, found in human skeletal muscle with high mass accuracy and comprehensive sequence coverage. Moreover, we have localized the phosphorylation site of slow sTnT isoform III to Ser1 by tandem MS with electron capture dissociation. This is the first study to comprehensively characterize human sTn and also the first to identify the basal phosphorylation site for human sTnT by top-down MS.
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21
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Ying P, Serife AG, Deyang Y, Ying G. Top-down mass spectrometry of cardiac myofilament proteins in health and disease. Proteomics Clin Appl 2014; 8:554-68. [PMID: 24945106 PMCID: PMC4231170 DOI: 10.1002/prca.201400043] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/21/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
Myofilaments are composed of thin and thick filaments that coordinate with each other to regulate muscle contraction and relaxation. PTMs together with genetic variations and alternative splicing of the myofilament proteins play essential roles in regulating cardiac contractility in health and disease. Therefore, a comprehensive characterization of the myofilament proteins in physiological and pathological conditions is essential for better understanding the molecular basis of cardiac function and dysfunction. Due to the vast complexity and dynamic nature of proteins, it is challenging to obtain a holistic view of myofilament protein modifications. In recent years, top-down MS has emerged as a powerful approach to study isoform composition and PTMs of proteins owing to its advantage of complete sequence coverage and its ability to identify PTMs and sequence variants without a priori knowledge. In this review, we will discuss the application of top-down MS to the study of cardiac myofilaments and highlight the insights it provides into the understanding of molecular mechanisms in contractile dysfunction of heart failure. Particularly, recent results of cardiac troponin and tropomyosin modifications will be elaborated. The limitations and perspectives on the use of top-down MS for myofilament protein characterization will also be briefly discussed.
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Affiliation(s)
- Peng Ying
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Ayaz-Guner Serife
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Yu Deyang
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Environmental Toxicology Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Ge Ying
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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22
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In-depth proteomic analysis of human tropomyosin by top-down mass spectrometry. J Muscle Res Cell Motil 2013; 34:199-210. [PMID: 23881156 DOI: 10.1007/s10974-013-9352-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 06/27/2013] [Indexed: 01/29/2023]
Abstract
Tropomyosins (Tms) are a family of highly conserved actin-binding proteins that play critical roles in a variety of processes, most notably, in the regulation of muscle contraction and relaxation. It is well known that different Tm isoforms have distinct functions and that altered expression of Tm isoforms could lead to changes in cardiac structure and function. To precisely define Tm isoform expression in the human heart, towards a better understanding of their functional roles, we have employed top-down mass spectrometry for in-depth proteomic characterization of Tm isoforms. Using a minimal amount of human heart tissue from rejected donor organs, we confirmed the presence of multiple Tm isoforms including α-Tm, β-Tm and κ-Tm in the human heart, with α-Tm being the predominant isoform, followed by minor isoforms of β-Tm and κ-Tm. Interestingly, our data revealed regional variations of Tm isoforms and post-translational modifications in the human heart. Specifically, the expression level of κ-Tm was highest in the left atrium but nearly undetectable in the left ventricle. The phosphorylation level of α-Tm (pα-Tm) was significantly higher in the atria than it was in the ventricles. The sequences of all Tm isoforms were characterized and the sites of post-translational modifications were localized. Clearly, top-down mass spectrometry is an attractive method for comprehensive characterization of Tm isoforms and post-translational modifications since it can universally detect and quantify all types of protein modifications without a priori knowledge and without the need for specific antibodies.
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23
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Tropomyosin isoform expression and phosphorylation in the human heart in health and disease. J Muscle Res Cell Motil 2013; 34:189-97. [PMID: 23712688 DOI: 10.1007/s10974-013-9347-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 05/09/2013] [Indexed: 01/08/2023]
Abstract
We determined the isoforms of tropomyosin expressed and the level of tropomyosin phosphorylation in donor, end-stage failing and hypertrophic obstructive cardiomyopathy samples of human heart muscle. Western blots and isoform-specific antibodies showed that α-tropomyosin was the only significant isoform expressed and that tropomyosin was 25-30% phosphorylated at serine 283. Mass spectrometry confirmed directly that α-tropomyosin made up over 95% of tropomyosin but also indicated the presence of up to 4% κ-tropomyosin and much smaller amounts of β-, γ- and smooth β-tropomyosin and about 26% phosphorylation. Neither the isoform distribution nor the level of phosphorylation changed significantly in the pathological heart muscle samples.
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24
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Ye J, Llorian M, Cardona M, Rongvaux A, Moubarak RS, Comella JX, Bassel-Duby R, Flavell RA, Olson EN, Smith CWJ, Sanchis D. A pathway involving HDAC5, cFLIP and caspases regulates expression of the splicing regulator polypyrimidine tract binding protein in the heart. J Cell Sci 2013; 126:1682-91. [PMID: 23424201 PMCID: PMC3647441 DOI: 10.1242/jcs.121384] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2013] [Indexed: 01/07/2023] Open
Abstract
Polypyrimidine tract binding protein (PTB) regulates pre-mRNA splicing, having special relevance for determining gene expression in the differentiating muscle. We have previously shown that PTB protein abundance is progressively reduced during heart development without reduction of its own transcript. Simultaneous reduction of histone deacetylase (HDAC) expression prompted us to investigate the potential link between these events. HDAC5-deficient mice have reduced cardiac PTB protein abundance, and HDAC inhibition in myocytes causes a reduction in endogenous expression of cellular FLICE-like inhibitory protein (cFLIP) and caspase-dependent cleavage of PTB. In agreement with this, cardiac PTB expression is abnormally high in mice with cardiac-specific executioner caspase deficiency, and cFLIP overexpression prevents PTB cleavage in vitro. Caspase-dependent cleavage triggers further fragmentation of PTB, and these fragments accumulate in the presence of proteasome inhibitors. Experimental modification of the above processes in vivo and in vitro results in coherent changes in the alternative splicing of genes encoding tropomyosin-1 (TPM1), tropomyosin-2 (TPM2) and myocyte enhancer factor-2 (MEF2). Thus, we report a pathway connecting HDAC, cFLIP and caspases regulating the progressive disappearance of PTB, which enables the expression of the adult variants of proteins involved in the regulation of contraction and transcription during cardiac muscle development.
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Affiliation(s)
- Junmei Ye
- Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida – IRBLLEIDA, Av Rovira Roure, 80, Lleida, 25198Spain
| | - Miriam Llorian
- Department of Biochemistry, University of Cambridge, Building O, Downing Site, Cambridge, CB2 1QW, UK
| | - Maria Cardona
- Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida – IRBLLEIDA, Av Rovira Roure, 80, Lleida, 25198Spain
| | - Anthony Rongvaux
- Department of Immunobiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Rana S. Moubarak
- Ciberned, Institut de Recerca Hospital, Universitari Vall d'Hebró-UAB, Barcelona, 08035, Spain
| | - Joan X. Comella
- Ciberned, Institut de Recerca Hospital, Universitari Vall d'Hebró-UAB, Barcelona, 08035, Spain
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA
| | - Richard A. Flavell
- Department of Immunobiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Eric N. Olson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA
| | - Christopher W. J. Smith
- Department of Biochemistry, University of Cambridge, Building O, Downing Site, Cambridge, CB2 1QW, UK
| | - Daniel Sanchis
- Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida – IRBLLEIDA, Av Rovira Roure, 80, Lleida, 25198Spain
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Peng Y, Chen X, Zhang H, Xu Q, Hacker TA, Ge Y. Top-down targeted proteomics for deep sequencing of tropomyosin isoforms. J Proteome Res 2013; 12:187-98. [PMID: 23256820 PMCID: PMC3596867 DOI: 10.1021/pr301054n] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Tropomyosins (Tm) constitute a family of ubiquitous and highly conserved actin-binding proteins, playing essential roles in a variety of biological processes. Tm isoforms produced by multiple Tm encoding genes and alternatively expressed exons along with post-translational modifications (PTMs) regulate Tm function. Therefore, to gain a better understanding of the functional role of Tm, it is essential to fully characterize Tm isoforms. Herein, we developed a top-down high-resolution mass spectrometry (MS)-based targeted proteomics method for comprehensive characterization of Tm isoforms. α-Tm was identified to be the predominant isoform in swine cardiac muscle. We further characterized its sequence and localized the PTMs such as acetylation and phosphorylation as well as amino acid polymorphisms. Interestingly, we discovered a "novel" Tm isoform that does not match with any of the currently available swine Tm sequences. A deep sequencing of this isoform by top-down MS revealed an exact match with mouse β-Tm sequence, suggesting that this "novel" isoform is swine β-Tm which is 100% conserved between swine and mouse. Taken together, we demonstrated that top-down targeted proteomics provides a powerful tool for deep sequencing of Tm isoforms from genetic variations together with complete mapping of the PTM sites.
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Affiliation(s)
- Ying Peng
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Xin Chen
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Han Zhang
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
| | - Qingge Xu
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Timothy A. Hacker
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706
| | - Ying Ge
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
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Myopathies associated with β-tropomyosin mutations. Neuromuscul Disord 2012; 22:923-33. [DOI: 10.1016/j.nmd.2012.05.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 05/09/2012] [Accepted: 05/31/2012] [Indexed: 12/29/2022]
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Bayliss CR, Jacques AM, Leung MC, Ward DG, Redwood CS, Gallon CE, Copeland O, McKenna WJ, Dos Remedios C, Marston SB, Messer AE. Myofibrillar Ca(2+) sensitivity is uncoupled from troponin I phosphorylation in hypertrophic obstructive cardiomyopathy due to abnormal troponin T. Cardiovasc Res 2012; 97:500-8. [PMID: 23097574 DOI: 10.1093/cvr/cvs322] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS We studied the relationship between myofilament Ca(2+) sensitivity and troponin I (TnI) phosphorylation by protein kinase A at serines 22/23 in human heart troponin isolated from donor hearts and from myectomy samples from patients with hypertrophic obstructive cardiomyopathy (HOCM). METHODS AND RESULTS We used a quantitative in vitro motility assay. With donor heart troponin, Ca(2+) sensitivity is two- to three-fold higher when TnI is unphosphorylated. In the myectomy samples from patients with HOCM, the mean level of TnI phosphorylation was low: 0.38 ± 0.19 mol Pi/mol TnI compared with 1.60 ± 0.19 mol Pi/mol TnI in donor hearts, but no difference in myofilament Ca(2+) sensitivity was observed. Thus, troponin regulation of thin filament Ca(2+) sensitivity is abnormal in HOCM hearts. HOCM troponin (0.29 mol Pi/mol TnI) was treated with protein kinase A to increase the level of phosphorylation to 1.56 mol Pi/mol TnI. No difference in EC(50) was found in thin filaments containing high and low TnI phosphorylation levels. This indicates that Ca(2+) sensitivity is uncoupled from TnI phosphorylation in HOCM heart troponin. Coupling could be restored by replacing endogenous troponin T (TnT) with the recombinant TnT T3 isoform. No difference in Ca(2+) sensitivity was observed if TnI was exchanged into HOCM heart troponin or if TnT was exchanged into the highly phosphorylated donor heart troponin. Comparison of donor and HOCM heart troponin by mass spectrometry and with adduct-specific antibodies did not show any differences in TnT isoform expression, phosphorylation or any post-translational modifications. CONCLUSION An abnormality in TnT is responsible for uncoupling myofibrillar Ca(2+) sensitivity from TnI phosphorylation in the septum of HOCM patients.
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Affiliation(s)
- Christopher R Bayliss
- Myocardial Function, NHLI, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
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Zhang L, Song Z, Chang H, Wang YY, Yu ZB. Enhanced N-terminal degradation of troponin I blunts cardiac function responsiveness to isoproterenol in 4-week tail-suspended rats. Mol Med Rep 2012; 7:271-9. [PMID: 23042367 DOI: 10.3892/mmr.2012.1119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 10/01/2012] [Indexed: 11/05/2022] Open
Abstract
The N-terminal extension of cardiac troponin I (cTnI) is important in regulating cardiac function. Although the normal rat myocardium shows some cTnI N-terminal degradation (cTnI-ND), exposure to 4 weeks of tail-suspension markedly increased cTnI-ND. We hypothesized that the increased cTnI-ND in tail-suspended rats may affect cardiac function, particularly during β-adrenergic (β-A) stimulation. The increase in cardiac output with isoproterenol (ISO) treatment was smaller in tail-suspended rats compared with controls. Left ventricular end-diastolic pressure was elevated and increases in maximal rates of left ventricular pressure development and relaxation were lower during ISO treatment in tail-suspended rats. Response to ISO, forskolin, DB-cAMP and IBMX was also lower in cardiomyocytes from tail-suspended rats. The increase in shortening and re-lengthening the rates of cardiomyocytes at a maximal dose of ISO, forskolin, DB-cAMP and IBMX treatment was limited in tail-suspended rats. There was no difference in Ca2+ sensitivity of the isometric force between tail-suspended and control rats, although Ca2+ sensitivity was decreased less in tail-suspended rats versus control rats during PKA phosphorylation. There was no difference in PKA protein expression and activation during ISO stimulation between the two groups. Due to the increase in cTnI-ND, ISO-induced phosphorylation of cTnI was reduced in tail-suspended rats. The total phospholamban expression and phosphorylation by ISO was unaltered in tail-suspended rat hearts. These data suggest that enhanced cTnI-ND following 4-week tail-suspension is a major component of the β-A receptor signaling pathway, depressing cardiac function under ISO stimulation.
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Affiliation(s)
- Lin Zhang
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an 710032, PR China
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Yuan C, Solaro RJ. Myofilament proteins: From cardiac disorders to proteomic changes. Proteomics Clin Appl 2012; 2:788-99. [PMID: 21136879 DOI: 10.1002/prca.200780076] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Myofilament proteins of the cardiac sarcomere house the molecular machinery responsible for generating tension and pressure. Release of intracellular Ca(2+) triggers myofilament tension generation and shortening, but the response to Ca(2+) is modulated by changes in key regulatory proteins. We review how these proteomic changes are essential to adaptive physiological regulation of cardiac output and become maladaptive in cardiac disorders. We also review the essentials of proteomic techniques used to study myofilament protein changes, including degradation, isoform expression, phosphorylation and oxidation. Selected proteomic studies illustrate the applications of these approaches.
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Affiliation(s)
- Chao Yuan
- Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL, USA
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Denz CR, Zhang C, Jia P, Du J, Huang X, Dube S, Thomas A, Poiesz BJ, Dube DK. Absence of mutation at the 5'-upstream promoter region of the TPM4 gene from cardiac mutant axolotl (Ambystoma mexicanum). Cardiovasc Toxicol 2011; 11:235-43. [PMID: 21626230 DOI: 10.1007/s12012-011-9117-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tropomyosins are a family of actin-binding proteins that show cell-specific diversity by a combination of multiple genes and alternative RNA splicing. Of the 4 different tropomyosin genes, TPM4 plays a pivotal role in myofibrillogenesis as well as cardiac contractility in amphibians. In this study, we amplified and sequenced the upstream regulatory region of the TPM4 gene from both normal and mutant axolotl hearts. To identify the cis-elements that are essential for the expression of the TPM4, we created various deletion mutants of the TPM4 promoter DNA, inserted the deleted segments into PGL3 vector, and performed promoter-reporter assay using luciferase as the reporter gene. Comparison of sequences of the promoter region of the TPM4 gene from normal and mutant axolotl revealed no mutations in the promoter sequence of the mutant TPM4 gene. CArG box elements that are generally involved in controlling the expression of several other muscle-specific gene promoters were not found in the upstream regulatory region of the TPM4 gene. In deletion experiments, loss of activity of the reporter gene was noted upon deletion which was then restored upon further deletion suggesting the presence of both positive and negative cis-elements in the upstream regulatory region of the TPM4 gene. We believe that this is the first axolotl promoter that has ever been cloned and studied with clear evidence that it functions in mammalian cell lines. Although striated muscle-specific cis-acting elements are absent from the promoter region of TPM4 gene, our results suggest the presence of positive and negative cis-elements in the promoter region, which in conjunction with positive and negative trans-elements may be involved in regulating the expression of TPM4 gene in a tissue-specific manner.
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Affiliation(s)
- Christopher R Denz
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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31
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Wang Y, Pinto JR, Solis RS, Dweck D, Liang J, Diaz-Perez Z, Ge Y, Walker JW, Potter JD. Generation and functional characterization of knock-in mice harboring the cardiac troponin I-R21C mutation associated with hypertrophic cardiomyopathy. J Biol Chem 2011; 287:2156-67. [PMID: 22086914 DOI: 10.1074/jbc.m111.294306] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The R21C substitution in cardiac troponin I (cTnI) is the only identified mutation within its unique N-terminal extension that is associated with hypertrophic cardiomyopathy (HCM) in man. Particularly, this mutation is located in the consensus sequence for β-adrenergic-activated protein kinase A (PKA)-mediated phosphorylation. The mechanisms by which this mutation leads to heart disease are still unclear. Therefore, we generated cTnI knock-in mouse models carrying an R21C mutation to evaluate the resultant functional consequences. Measuring the in vivo levels of incorporated mutant and WT cTnI, and their basal phosphorylation levels by top-down mass spectrometry demonstrated: 1) a dominant-negative effect such that, the R21C+/- hearts incorporated 24.9% of the mutant cTnI within the myofilament; and 2) the R21C mutation abolished the in vivo phosphorylation of Ser(23)/Ser(24) in the mutant cTnI. Adult heterozygous (R21C+/-) and homozygous (R21C+/+) mutant mice activated the fetal gene program and developed a remarkable degree of cardiac hypertrophy and fibrosis. Investigation of cardiac skinned fibers isolated from WT and heterozygous mice revealed that the WT cTnI was completely phosphorylated at Ser(23)/Ser(24) unless the mice were pre-treated with propranolol. After propranolol treatment (-PKA), the pCa-tension relationships of all three mice (i.e. WT, R21C+/-, and R21C+/+) were essentially the same. However, after treatment with propranolol and PKA, the R21C cTnI mutation reduced (R21C+/-) or abolished (R21C+/+) the well known decrease in the Ca(2+) sensitivity of tension that accompanies Ser(23)/Ser(24) cTnI phosphorylation. Altogether, the combined effects of the R21C mutation appear to contribute toward the development of HCM and suggest that another physiological role for the phosphorylation of Ser(23)/Ser(24) in cTnI is to prevent cardiac hypertrophy.
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Affiliation(s)
- Yingcai Wang
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, Florida 33136, USA
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Zhang J, Guy MJ, Norman HS, Chen YC, Xu Q, Dong X, Guner H, Wang S, Kohmoto T, Young KH, Moss RL, Ge Y. Top-down quantitative proteomics identified phosphorylation of cardiac troponin I as a candidate biomarker for chronic heart failure. J Proteome Res 2011; 10:4054-65. [PMID: 21751783 DOI: 10.1021/pr200258m] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The rapid increase in the prevalence of chronic heart failure (CHF) worldwide underscores an urgent need to identify biomarkers for the early detection of CHF. Post-translational modifications (PTMs) are associated with many critical signaling events during disease progression and thus offer a plethora of candidate biomarkers. We have employed a top-down quantitative proteomics methodology for comprehensive assessment of PTMs in whole proteins extracted from normal and diseased tissues. We systematically analyzed 36 clinical human heart tissue samples and identified phosphorylation of cardiac troponin I (cTnI) as a candidate biomarker for CHF. The relative percentages of the total phosphorylated cTnI forms over the entire cTnI populations (%P(total)) were 56.4 ± 3.5%, 36.9 ± 1.6%, 6.1 ± 2.4%, and 1.0 ± 0.6% for postmortem hearts with normal cardiac function (n = 7), early stage of mild hypertrophy (n = 5), severe hypertrophy/dilation (n = 4), and end-stage CHF (n = 6), respectively. In fresh transplant samples, the %P(total) of cTnI from nonfailing donor (n = 4), and end-stage failing hearts (n = 10) were 49.5 ± 5.9% and 18.8 ± 2.9%, respectively. Top-down MS with electron capture dissociation unequivocally localized the altered phosphorylation sites to Ser22/23 and determined the order of phosphorylation/dephosphorylation. This study represents the first clinical application of top-down MS-based quantitative proteomics for biomarker discovery from tissues, highlighting the potential of PTMs as disease biomarkers.
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Affiliation(s)
- Jiang Zhang
- School of Medicine and Public Health and School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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Copeland O, Nowak KJ, Laing NG, Ravenscroft G, Messer AE, Bayliss CR, Marston SB. Investigation of changes in skeletal muscle alpha-actin expression in normal and pathological human and mouse hearts. J Muscle Res Cell Motil 2010; 31:207-14. [PMID: 20706863 DOI: 10.1007/s10974-010-9224-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Accepted: 07/21/2010] [Indexed: 10/19/2022]
Abstract
We have developed a quantitative antibody-based assay to measure the content of skeletal muscle alpha-actin relative to cardiac alpha-actin. We found 21 +/- 2% skeletal muscle alpha-actin content in normal heart muscle of adult man and mouse. In end stage failing heart 53 +/- 5% of striated actin was skeletal muscle alpha-actin and in samples of inter-ventricular septum from patients with hypertrophic obstructive cardiomyopathy (HOCM) skeletal muscle alpha-actin was 72 +/- 2% of sarcomeric actin. Thin filaments containing actin isolated from normal and HOCM heart muscle were functionally indistinguishable when studied by quantitative in vitro motility assay. We also found elevated skeletal muscle alpha-actin (60 +/- 7%) in a mouse model of dilated cardiomyopathy.
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Affiliation(s)
- O'Neal Copeland
- NHLI, Cardiovascular Science, Imperial College London, London, UK
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34
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Dubois E, Richard V, Mulder P, Lamblin N, Drobecq H, Henry JP, Amouyel P, Thuillez C, Bauters C, Pinet F. Decreased serine207 phosphorylation of troponin T as a biomarker for left ventricular remodelling after myocardial infarction. Eur Heart J 2010; 32:115-23. [PMID: 20418543 DOI: 10.1093/eurheartj/ehq108] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Chronic heart failure following myocardial infarction (MI) is characterized by progressive left ventricular remodelling (LVR). Despite significant improvements in MI management, LVR remains a frequent complication. Although several risk factors have been identified, such as infarct size, LVR is difficult to predict in clinical practice. METHODS AND RESULTS Using a rat model of MI and phosphoproteomic technology, we discovered that remodelling is associated with decreased levels of myocardial and plasma serine(208)-phosphorylated troponin T (TnT). To confirm the association in human plasma, we developed new specific polyclonal antibodies against human/rat serine(207/208)-phosphorylated TnT and tested plasma obtained in the first week after MI from patients with low, intermediate, and high remodelling a year later. We observed a significant decrease of serine(207)-phosphorylated TnT and of the serine(207)-phosphorylated TnT/total TnT ratio in those with intermediate or high LVR. These differences remained statistically significant when adjusted for other determinants of LVR. In contrast, baseline B-type natriuretic peptide levels were not associated with LVR. CONCLUSION The level of circulating phosphorylated TnT could be a new biomarker of LVR.
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35
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Rajan S, Jagatheesan G, Karam CN, Alves ML, Bodi I, Schwartz A, Bulcao CF, D'Souza KM, Akhter SA, Boivin GP, Dube DK, Petrashevskaya N, Herr AB, Hullin R, Liggett SB, Wolska BM, Solaro RJ, Wieczorek DF. Molecular and functional characterization of a novel cardiac-specific human tropomyosin isoform. Circulation 2010; 121:410-8. [PMID: 20065163 DOI: 10.1161/circulationaha.109.889725] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Tropomyosin (TM), an essential actin-binding protein, is central to the control of calcium-regulated striated muscle contraction. Although TPM1alpha (also called alpha-TM) is the predominant TM isoform in human hearts, the precise TM isoform composition remains unclear. METHODS AND RESULTS In this study, we quantified for the first time the levels of striated muscle TM isoforms in human heart, including a novel isoform called TPM1kappa. By developing a TPM1kappa-specific antibody, we found that the TPM1kappa protein is expressed and incorporated into organized myofibrils in hearts and that its level is increased in human dilated cardiomyopathy and heart failure. To investigate the role of TPM1kappa in sarcomeric function, we generated transgenic mice overexpressing cardiac-specific TPM1kappa. Incorporation of increased levels of TPM1kappa protein in myofilaments leads to dilated cardiomyopathy. Physiological alterations include decreased fractional shortening, systolic and diastolic dysfunction, and decreased myofilament calcium sensitivity with no change in maximum developed tension. Additional biophysical studies demonstrate less structural stability and weaker actin-binding affinity of TPM1kappa compared with TPM1alpha. CONCLUSIONS This functional analysis of TPM1kappa provides a possible mechanism for the consequences of the TM isoform switch observed in dilated cardiomyopathy and heart failure patients.
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Affiliation(s)
- Sudarsan Rajan
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati Medical Center, Cincinnati, OH 45267-0524, USA
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36
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Tondeleir D, Vandamme D, Vandekerckhove J, Ampe C, Lambrechts A. Actin isoform expression patterns during mammalian development and in pathology: insights from mouse models. ACTA ACUST UNITED AC 2009; 66:798-815. [PMID: 19296487 DOI: 10.1002/cm.20350] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The dynamic actin cytoskeleton, consisting of six actin isoforms in mammals and a variety of actin binding proteins is essential for all developmental processes and for the viability of the adult organism. Actin isoform specific functions have been proposed for muscle contraction, cell migration, endo- and exocytosis and maintaining cell shape. However, these specific functions for each of the actin isoforms during development are not well understood. Based on transgenic mouse models, we will discuss the expression patterns of the six conventional actin isoforms in mammals during development and adult life. Ablation of actin genes usually leads to lethality and affects expression of other actin isoforms at the cell or tissue level. A good knowledge of their expression and functions will contribute to fully understand severe phenotypes or diseases caused by mutations in actin isoforms.
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Affiliation(s)
- Davina Tondeleir
- Department of Medical Protein Research, Flanders Interuniversity Institute for Biotechnology (VIB), Albert Baertsoenkaai 3, Ghent, Belgium
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37
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Sumandea MP, Vahebi S, Sumandea CA, Garcia-Cazarin ML, Staidle J, Homsher E. Impact of cardiac troponin T N-terminal deletion and phosphorylation on myofilament function. Biochemistry 2009; 48:7722-31. [PMID: 19586048 DOI: 10.1021/bi900516n] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cardiac troponin T (cTnT) is a phosphoprotein that modulates cardiac muscle contraction through its extensive and diverse interactions with neighboring thin filament proteins. Its N-terminal half is the "glue" that anchors the troponin complex to tropomyosin-actin. Until now, studies aimed at investigating the role of the N-terminal tail region have not considered the effects of phosphorylation. To understand better the regulatory role of the N-terminal tail region of phosphorylated cTnT, we investigated the functional effects of N-terminal deletion (amino acids 1-91) and phosphorylation on Ca(2+) dependence of myofilament isometric force production, isometric ATPase rate, and thin filament sliding speed. Chemomechanical profiles were assessed in detergent permeabilized fiber preparations where the native troponin (cTn) was exchanged with recombinant cTn engineered to contain modified cTnT (truncated, phosphorylated) in the presence of wild-type cTnI and cTnC. Removal of the cTnT N-terminal amino acids 1-91 (cTnT-del) enhances myofilament responsiveness to nonsaturating Ca(2+) levels (the physiological range in cardiac myocytes). However, at saturating Ca(2+) levels, there is a reduction in isometric tension and ATPase rate. On one hand, phosphorylation of cTnT-del attenuates the sensitizing effect induced by truncation of the N-terminal tail, "resetting" myofilament Ca(2+) responsiveness back to control levels. On the other hand, it impairs isometric tension development and ATPase rate. Interestingly, phosphorylation of cTnT (cTnT-P) differentially regulates tension cost (an index of cross-bridge cycling rate): increased by cTn-del-P and decreased by intact cTn-wt-P. Like the isometric fiber data, sliding speed of thin filaments regulated by cTn-del is more sensitive to Ca(2+) compared with cTn-wt. Phosphorylation of cTnT (whether cTnT-del or -wt) depresses sliding speed and is associated with Ca(2+) desensitization of thin filament sliding speed.
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Affiliation(s)
- Marius P Sumandea
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA.
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38
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Wiegerinck RF, Cojoc A, Zeidenweber CM, Ding G, Shen M, Joyner RW, Fernandez JD, Kanter KR, Kirshbom PM, Kogon BE, Wagner MB. Force frequency relationship of the human ventricle increases during early postnatal development. Pediatr Res 2009; 65:414-9. [PMID: 19127223 PMCID: PMC2788428 DOI: 10.1203/pdr.0b013e318199093c] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Understanding developmental changes in contractility is critical to improving therapies for young cardiac patients. Isometric developed force was measured in human ventricular muscle strips from two age groups: newborns (<2 wk) and infants (3-14 mo) undergoing repair for congenital heart defects. Muscle strips were paced at several cycle lengths (CLs) to determine the force frequency response (FFR). Changes in Na/Ca exchanger (NCX), sarcoplasmic reticulum Ca-ATPase (SERCA), and phospholamban (PLB) were characterized. At CL 2000 ms, developed force was similar in the two groups. Decreasing CL increased developed force in the infant group to 131 +/- 8% (CL 1000 ms) and 157 +/- 18% (CL 500 ms) demonstrating a positive FFR. The FFR in the newborn group was flat. NCX mRNA and protein levels were significantly larger in the newborn than infant group whereas SERCA levels were unchanged. PLB mRNA levels and PLB/SERCA ratio increased with age. Immunostaining for NCX in isolated newborn cells showed peripheral staining. In infant cells, NCX was also found in T-tubules. SERCA staining was regular and striated in both groups. This study shows for the first time that the newborn human ventricle has a flat FFR, which increases with age and may be caused by developmental changes in calcium handling.
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Affiliation(s)
- Rob F Wiegerinck
- Department of Pediatrics, Emory University, Atlanta, Georgia 30322, USA
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Hausner E, Fiszman ML, Hanig J, Harlow P, Zornberg G, Sobel S. Long-term consequences of drugs on the paediatric cardiovascular system. Drug Saf 2009; 31:1083-96. [PMID: 19026026 DOI: 10.2165/0002018-200831120-00005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many pharmacological and toxicological actions of drugs in children cannot be fully predicted from adult clinical experience or from standard non-clinical toxicology studies. Numerous drugs have direct or indirect pharmacological effects on the heart and are prescribed for children of all ages. Toxicity or secondary effects may be immediate or delayed for years after drug exposure has ceased. Originally, the aim of this review was to compile information on the effect of specific drugs on the post-natal development of the cardiovascular system and to examine long-term follow-up of the use of cardio-active drugs in children. The limited database of published information caused the original question to evolve into an examination of the medical literature for three areas of information: (i) whether vulnerable developmental windows have been identified that reflect the substantial functional development that the cardiovascular system undergoes after birth; (ii) what is known about pharmacological perturbation of development; and (iii) what the likelihood is of drug exposure during childhood. We examined different scenarios for exposure including random, isolated exposure, conditions historically associated with adults, primary or secondary cardiac disease, psychiatric and neurological conditions, asthma, cancer and HIV. Except for random, isolated drug exposures, each category of possible exposure contained numerous drugs known to have either primary or secondary effects on the cardiovascular system or to influence factors associated with atherosclerosis. It is likely that a significant number of children will be prescribed drugs having either direct or indirect effects upon the immature cardiovascular system. A confounding factor is the simultaneous use of over-the-counter medications and herbal or nutraceutical preparations that a patient, parent or guardian does not mention to a prescribing physician. Metabolism is also important in assessing drug effects in children. Differences in body water : body fat ratio, age-related gastrointestinal absorption, distribution, excretion, renal function and drug metabolizing capabilities make it possible for children to have a different metabolite profile for a drug compared with adults. There is little examination of drug effects on the interdependent processes of cardiac maturation and less examination of metabolite effects. It is difficult to identify delayed toxicities in children as these adverse events may take years to manifest with many patients lost to follow-up. Clearly this is an area of study where intermediate endpoints and surrogate markers would be of great benefit. Pharmacogenomics may be useful in providing markers of increased risk or susceptibility. A perspective must be kept in balancing the possibility of a problem with the very real benefits that many children experience from the use of these pharmaceuticals.
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Perlman DH, Bauer SM, Ashrafian H, Bryan NS, Garcia-Saura MF, Lim CC, Fernandez BO, Infusini G, McComb ME, Costello CE, Feelisch M. Mechanistic insights into nitrite-induced cardioprotection using an integrated metabolomic/proteomic approach. Circ Res 2009; 104:796-804. [PMID: 19229060 DOI: 10.1161/circresaha.108.187005] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitrite has recently emerged as an important bioactive molecule, capable of conferring cardioprotection and a variety of other benefits in the cardiovascular system and elsewhere. The mechanisms by which it accomplishes these functions remain largely unclear. To characterize the dose response and corresponding cardiac sequelae of transient systemic elevations of nitrite, we assessed the time course of oxidation/nitros(yl)ation, as well as the metabolomic, proteomic, and associated functional changes in rat hearts following acute exposure to nitrite in vivo. Transient systemic nitrite elevations resulted in: (1) rapid formation of nitroso and nitrosyl species; (2) moderate short-term changes in cardiac redox status; (3) a pronounced increase in selective manifestations of long-term oxidative stress as evidenced by cardiac ascorbate oxidation, persisting long after changes in nitrite-related metabolites had normalized; (4) lasting reductions in glutathione oxidation (GSSG/GSH) and remarkably concordant nitrite-induced cardioprotection, which both followed a complex dose-response profile; and (5) significant nitrite-induced protein modifications (including phosphorylation) revealed by mass spectrometry-based proteomic studies. Altered proteins included those involved in metabolism (eg, aldehyde dehydrogenase 2, ubiquinone biosynthesis protein CoQ9, lactate dehydrogenase B), redox regulation (eg, protein disulfide isomerase A3), contractile function (eg, filamin-C), and serine/threonine kinase signaling (eg, protein kinase A R1alpha, protein phosphatase 2A A R1-alpha). Thus, brief elevations in plasma nitrite trigger a concerted cardioprotective response characterized by persistent changes in cardiac metabolism, redox stress, and alterations in myocardial signaling. These findings help elucidate possible mechanisms of nitrite-induced cardioprotection and have implications for nitrite dosing in therapeutic regimens.
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Affiliation(s)
- David H Perlman
- Cardiovascular Proteomics Center, Boston University School of Medicine, Boston, MA, USA
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41
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Monnier N, Lunardi J, Marty I, Mezin P, Labarre-Vila A, Dieterich K, Jouk PS. Absence of β-tropomyosin is a new cause of Escobar syndrome associated with nemaline myopathy. Neuromuscul Disord 2009; 19:118-23. [DOI: 10.1016/j.nmd.2008.11.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 11/02/2008] [Accepted: 11/06/2008] [Indexed: 10/21/2022]
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42
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Feng JJ, Marston S. Genotype–phenotype correlations in ACTA1 mutations that cause congenital myopathies. Neuromuscul Disord 2009; 19:6-16. [DOI: 10.1016/j.nmd.2008.09.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 12/01/2022]
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Markel TA, Wairiuko GM, Lahm T, Crisostomo PR, Wang M, Herring CM, Meldrum DR. The Right Heart and Its Distinct Mechanisms of Development, Function, and Failure. J Surg Res 2008; 146:304-13. [DOI: 10.1016/j.jss.2007.04.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 03/27/2007] [Accepted: 04/02/2007] [Indexed: 01/21/2023]
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Human tropomyosin isoforms in the regulation of cytoskeleton functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 644:201-22. [PMID: 19209824 DOI: 10.1007/978-0-387-85766-4_16] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Over the past two decades, extensive molecular studies have identified multiple tropomyosin isoforms existing in all mammalian cells and tissues. In humans, tropomyosins are encoded by TPM1 (alpha-Tm, 15q22.1), TPM2 (beta-Tm, 9p13.2-p13.1), TPM3 (gamma-Tm, 1q21.2) and TPM4 (delta-Tm, 19p13.1) genes. Through the use of different promoters, alternatively spliced exons and different sites of poly(A) addition signals, at least 22 different tropomyosin cDNAs with full-length open reading frame have been cloned. Compelling evidence suggests that these isoforms play important determinants for actin cytoskeleton functions, such as intracellular vesicle movement, cell migration, cytokinesis, cell proliferation and apoptosis. In vitro biochemical studies and in vivo localization studies suggest that different tropomyosin isoforms have differences in their actin-binding properties and their effects on other actin-binding protein functions and thus, in their specification ofactin microfilaments. In this chapter, we will review what has been learned from experimental studies on human tropomyosin isoforms about the mechanisms for differential localization and functions of tropomyosin. First, we summarize current information concerning human tropomyosin isoforms and relate this to the functions of structural homologues in rodents. We will discuss general strategies for differential localization oftropomyosin isoforms, particularly focusing on differential protein turnover and differential isoform effects on other actin binding protein functions. We will then review tropomyosin functions in regulating cell motility and in modulating the anti-angiogenic activity of cleaved high molecular weight kininogen (HKa) and discuss future directions in this area.
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45
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Abstract
This review briefly synthesizes the molecular biology of troponin, which is currently the best biochemical marker for the detection of cardiac injury and, thus, acute myocardial infarction as well. Potential new uses for the marker based on these insights, with a specific interest in cardiac troponin fragments that potentially could be linked to distinct clinical conditions, are described. Some of the clinical problems clinicians are faced with including how to use the markers in renal failure and the difficulties associated with the heterogeneity of current troponin assays are also discussed. Finally, we present the possibility of specific cardiac troponin fragments resulting from modification or degradation, associated with distinct pathological processes, as new potential uses for this biomarker.
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Affiliation(s)
- Vlad C Vasile
- Mayo Clinic & Mayo Medical School, Department of Internal Medicine, Division of Cardiovascular Diseases & Department of Laboratory Medicine & Pathology, Rochester, Minnesota, USA
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46
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Parnes D, Jacoby V, Sharabi A, Schlesinger H, Brand T, Kessler-Icekson G. The Popdc gene family in the rat: molecular cloning, characterization and expression analysis in the heart and cultured cardiomyocytes. ACTA ACUST UNITED AC 2007; 1769:586-92. [PMID: 17662479 DOI: 10.1016/j.bbaexp.2007.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2007] [Revised: 04/22/2007] [Accepted: 06/08/2007] [Indexed: 11/23/2022]
Abstract
Three Popeye domain-containing (Popdc 1-3) family-members are known in vertebrates. Their exact function is as yet unknown although involvement in cell adhesion has been suggested. We report herein sequencing of the rat Popdc 1-3 cDNAs that show high homology to other vertebrate orthologs and are expressed primarily in the heart and skeletal muscles. Popdc2 splice variants were identified, with Popdc2C showing a distinctive age-dependent decline. In isolated cardiomyocytes, Popdc genes were negatively regulated by serum, an effect that was reversed by EGFR-kinase inhibition, suggesting an EGFR-dependent modulation of Popdc gene expression.
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Affiliation(s)
- Doris Parnes
- Basil and Gerald Felsenstein Medical Research Center, Sackler Faculty of Medicine, Tel-Aviv University, Beilinson Campus, Rabin Medical Center, Petach-Tikva 49100, Israel
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47
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Messer AE, Jacques AM, Marston SB. Troponin phosphorylation and regulatory function in human heart muscle: dephosphorylation of Ser23/24 on troponin I could account for the contractile defect in end-stage heart failure. J Mol Cell Cardiol 2006; 42:247-59. [PMID: 17081561 DOI: 10.1016/j.yjmcc.2006.08.017] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 08/19/2006] [Accepted: 08/24/2006] [Indexed: 11/27/2022]
Abstract
We made quantitative measurements of phosphorylation in troponin isolated from 6 non-failing donor hearts and 6 explanted hearts with end-stage heart failure in SDS-PAGE gels using Pro-Q Diamond phosphoprotein stain. The troponin T phosphorylation level was the same in troponin from failing and non-failing heart (3.1 mol Pi/mol). However, troponin I phosphorylation was significantly lower in failing (0.37+/-0.18 mol Pi/mol) compared with non-failing heart troponin (2.25+/-0.36 mol Pi/mol). Levels of troponin I PKA-dependent phosphorylation, measured with a phosphoserine 23/24-specific antibody, were also significantly lower in failing heart troponin (0.19+/-0.06 mol Pi/mol) compared to non-failing troponin (1.14+/-0.09 mol Pi/mol). We calculate that there is phosphorylation in addition to serine 23/24 of 1.11+/-0.34 mol Pi/mol in non-failing reduced to 0.18+/-0.17 mol Pi/mol in failing heart troponin, attributed to phosphorylation on the PKC sites. To test for the functional role of troponin I phosphorylation, the native troponin I from either non-failing or failing heart troponin was exchanged for a recombinant (unphosphorylated) human cardiac troponin I. Thin filament Ca(2+)-regulatory function was studied with the quantitative in vitro motility assay: thin filaments containing the replaced troponin I resulted in a failing phenotype of a 17-26% reduced sliding speed and an increased Ca(2+)-sensitivity relative to non-failing troponin (EC(50) TnI-exchanged/non-failing=0.57, p<0.001). When exchanged with troponin I phosphorylated with PKA motility parameters reverted to a pattern indistinguishable from non-failing troponin (p=0.35-0.75). We suggest that changes in troponin function can account for the contractile abnormality in failing heart muscle and that the functional changes in troponin are due to reduced phosphorylation of troponin I at the PKA sites.
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Affiliation(s)
- Andrew E Messer
- National Heart and Lung Institute, Imperial College London, Dovehouse Street, London SW3 6LY, UK
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48
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D'Amico A, Graziano C, Pacileo G, Petrini S, Nowak KJ, Boldrini R, Jacques A, Feng JJ, Porfirio B, Sewry CA, Santorelli FM, Limongelli G, Bertini E, Laing N, Marston SB. Fatal hypertrophic cardiomyopathy and nemaline myopathy associated with ACTA1 K336E mutation. Neuromuscul Disord 2006; 16:548-52. [PMID: 16945537 DOI: 10.1016/j.nmd.2006.07.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 07/04/2006] [Accepted: 07/04/2006] [Indexed: 11/25/2022]
Abstract
We report on a 2-year-old male child with both nemaline myopathy and hypertrophic cardiomyopathy (HCM). Sequencing of the ACTA1 gene showed a "de novo" missense heterozygous mutation a>g in exon 7 (Lys336Glu). Two-dimensional electrophoresis showed 28% mutant actin present in his muscle biopsy. Actin was isolated from the muscle biopsy and examined by in vitro motility assay. The sliding speed was 13+/-3% less than normal and the affinity of actin for the Z-line protein alpha-actinin was reduced 10 fold. This is the first report on a hypertrophic cardiomyopathy associated with nemaline myopathy and an ACTA1 mutation.
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MESH Headings
- Actinin/metabolism
- Actins/genetics
- Amino Acid Substitution/genetics
- Cardiomyopathy, Hypertrophic, Familial/complications
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Child, Preschool
- DNA Mutational Analysis
- Fatal Outcome
- Genetic Predisposition to Disease/genetics
- Genetic Testing
- Glutamic Acid/genetics
- Humans
- Lysine/genetics
- Male
- Muscle Contraction/genetics
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Mutation, Missense/genetics
- Myocardium/metabolism
- Myocardium/pathology
- Myopathies, Nemaline/complications
- Myopathies, Nemaline/genetics
- Myopathies, Nemaline/physiopathology
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Affiliation(s)
- Adele D'Amico
- Unit of Molecular Medicine and Pathology, Dept. of Laboratory Medicine, Bambino Gesu' Children's Research Hospital, Rome, Italy
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49
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50
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Belin RJ, Sumandea MP, Kobayashi T, Walker LA, Rundell VL, Urboniene D, Yuzhakova M, Ruch SH, Geenen DL, Solaro RJ, de Tombe PP. Left ventricular myofilament dysfunction in rat experimental hypertrophy and congestive heart failure. Am J Physiol Heart Circ Physiol 2006; 291:H2344-53. [PMID: 16815982 DOI: 10.1152/ajpheart.00541.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is currently unclear whether left ventricular (LV) myofilament function is depressed in experimental LV hypertrophy (LVH) or congestive heart failure (CHF). To address this issue, we studied pressure overload-induced LV hypertrophy (POLVH) and myocardial infarction-elicited congestive heart failure (MICHF) in rats. LV myocytes were isolated from control, POLVH, and MICHF hearts by mechanical homogenization, skinned with Triton, and attached to micropipettes that projected from a sensitive force transducer and high-speed motor. A subset of cells was treated with either unphosphorylated, recombinant cardiac troponin (cTn) or cTn purified from either control or failing ventricles. LV myofilament function was characterized by the force-[Ca(2+)] relation yielding Ca(2+)-saturated maximal force (F(max)), myofilament Ca(2+) sensitivity (EC(50)), and cooperativity (Hill coefficient, n(H)) parameters. POLVH was associated with a 35% reduction in F(max) and 36% increase in EC(50). Similarly, MICHF resulted in a 42% reduction in F(max) and a 30% increase in EC(50). Incorporation of recombinant cTn or purified control cTn into failing cells restored myofilament Ca(2+) sensitivity toward levels observed in control cells. In contrast, integration of cTn purified from failing ventricles into control myocytes increased EC(50) to levels observed in failing myocytes. The F(max) parameter was not markedly affected by troponin exchange. cTnI phosphorylation was increased in both POLVH and MICHF left ventricles. We conclude that depressed myofilament Ca(2+) sensitivity in experimental LVH and CHF is due, in part, to a decreased functional role of cTn that likely involves augmented phosphorylation of cTnI.
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Affiliation(s)
- Rashad J Belin
- Dept. of Physiology & Biophysics, Univ. of Illinois at Chicago, 835 S. Wolcott (M/C 901 Chicago, IL 60612, USA
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