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Zuo B, Fan X, Xu D, Zhao L, Zhang B, Li X. Deciphering the mitochondria-inflammation axis: Insights and therapeutic strategies for heart failure. Int Immunopharmacol 2024; 139:112697. [PMID: 39024750 DOI: 10.1016/j.intimp.2024.112697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2024] [Revised: 07/10/2024] [Accepted: 07/13/2024] [Indexed: 07/20/2024]
Abstract
Heart failure (HF) is a clinical syndrome resulting from left ventricular systolic and diastolic dysfunction, leading to significant morbidity and mortality worldwide. Despite improvements in medical treatment, the prognosis of HF patients remains unsatisfactory, with high rehospitalization rates and substantial economic burdens. The heart, a high-energy-consuming organ, relies heavily on ATP production through oxidative phosphorylation in mitochondria. Mitochondrial dysfunction, characterized by impaired energy production, oxidative stress, and disrupted calcium homeostasis, plays a crucial role in HF pathogenesis. Additionally, inflammation contributes significantly to HF progression, with elevated levels of circulating inflammatory cytokines observed in patients. The interplay between mitochondrial dysfunction and inflammation involves shared risk factors, signaling pathways, and potential therapeutic targets. This review comprehensively explores the mechanisms linking mitochondrial dysfunction and inflammation in HF, including the roles of mitochondrial reactive oxygen species (ROS), calcium dysregulation, and mitochondrial DNA (mtDNA) release in triggering inflammatory responses. Understanding these complex interactions offers insights into novel therapeutic approaches for improving mitochondrial function and relieving oxidative stress and inflammation. Targeted interventions that address the mitochondria-inflammation axis hold promise for enhancing cardiac function and outcomes in HF patients.
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Affiliation(s)
- Baile Zuo
- Molecular Immunology and Immunotherapy Laboratory, School of Medical Technology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Xiu Fan
- Department of Blood Transfusion, Shanxi Provincial People's Hospital, Taiyuan, Shanxi, China
| | - Dawei Xu
- Department of Blood Transfusion, Shanxi Provincial People's Hospital, Taiyuan, Shanxi, China
| | - Liping Zhao
- Department of Pathology, Shanxi Provincial People's Hospital, Taiyuan, China
| | - Bi Zhang
- Department of Blood Transfusion, Shanxi Provincial People's Hospital, Taiyuan, Shanxi, China.
| | - Xiaoyan Li
- Department of Blood Transfusion, Shanxi Provincial People's Hospital, Taiyuan, Shanxi, China; Department of Clinical Laboratory, Heping Branch, Shanxi Provincial People's Hospital, Taiyuan, Shanxi, China.
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Solaro RJ, Goldspink PH, Wolska BM. Emerging Concepts of Mechanisms Controlling Cardiac Tension: Focus on Familial Dilated Cardiomyopathy (DCM) and Sarcomere-Directed Therapies. Biomedicines 2024; 12:999. [PMID: 38790961 PMCID: PMC11117855 DOI: 10.3390/biomedicines12050999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/28/2024] [Accepted: 04/30/2024] [Indexed: 05/26/2024] Open
Abstract
Novel therapies for the treatment of familial dilated cardiomyopathy (DCM) are lacking. Shaping research directions to clinical needs is critical. Triggers for the progression of the disorder commonly occur due to specific gene variants that affect the production of sarcomeric/cytoskeletal proteins. Generally, these variants cause a decrease in tension by the myofilaments, resulting in signaling abnormalities within the micro-environment, which over time result in structural and functional maladaptations, leading to heart failure (HF). Current concepts support the hypothesis that the mutant sarcomere proteins induce a causal depression in the tension-time integral (TTI) of linear preparations of cardiac muscle. However, molecular mechanisms underlying tension generation particularly concerning mutant proteins and their impact on sarcomere molecular signaling are currently controversial. Thus, there is a need for clarification as to how mutant proteins affect sarcomere molecular signaling in the etiology and progression of DCM. A main topic in this controversy is the control of the number of tension-generating myosin heads reacting with the thin filament. One line of investigation proposes that this number is determined by changes in the ratio of myosin heads in a sequestered super-relaxed state (SRX) or in a disordered relaxed state (DRX) poised for force generation upon the Ca2+ activation of the thin filament. Contrasting evidence from nanometer-micrometer-scale X-ray diffraction in intact trabeculae indicates that the SRX/DRX states may have a lesser role. Instead, the proposal is that myosin heads are in a basal OFF state in relaxation then transfer to an ON state through a mechano-sensing mechanism induced during early thin filament activation and increasing thick filament strain. Recent evidence about the modulation of these mechanisms by protein phosphorylation has also introduced a need for reconsidering the control of tension. We discuss these mechanisms that lead to different ideas related to how tension is disturbed by levels of mutant sarcomere proteins linked to the expression of gene variants in the complex landscape of DCM. Resolving the various mechanisms and incorporating them into a unified concept is crucial for gaining a comprehensive understanding of DCM. This deeper understanding is not only important for diagnosis and treatment strategies with small molecules, but also for understanding the reciprocal signaling processes that occur between cardiac myocytes and their micro-environment. By unraveling these complexities, we can pave the way for improved therapeutic interventions for managing DCM.
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Affiliation(s)
- R. John Solaro
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612, USA; (P.H.G.); (B.M.W.)
| | - Paul H. Goldspink
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612, USA; (P.H.G.); (B.M.W.)
| | - Beata M. Wolska
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612, USA; (P.H.G.); (B.M.W.)
- Department of Medicine, Section of Cardiology, University of Illinois at Chicago, Chicago, IL 60612, USA
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3
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Garg A, Lavine KJ, Greenberg MJ. Assessing Cardiac Contractility From Single Molecules to Whole Hearts. JACC Basic Transl Sci 2024; 9:414-439. [PMID: 38559627 PMCID: PMC10978360 DOI: 10.1016/j.jacbts.2023.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/14/2023] [Accepted: 07/14/2023] [Indexed: 04/04/2024]
Abstract
Fundamentally, the heart needs to generate sufficient force and power output to dynamically meet the needs of the body. Cardiomyocytes contain specialized structures referred to as sarcomeres that power and regulate contraction. Disruption of sarcomeric function or regulation impairs contractility and leads to cardiomyopathies and heart failure. Basic, translational, and clinical studies have adapted numerous methods to assess cardiac contraction in a variety of pathophysiological contexts. These tools measure aspects of cardiac contraction at different scales ranging from single molecules to whole organisms. Moreover, these studies have revealed new pathogenic mechanisms of heart disease leading to the development of novel therapies targeting contractility. In this review, the authors explore the breadth of tools available for studying cardiac contractile function across scales, discuss their strengths and limitations, highlight new insights into cardiac physiology and pathophysiology, and describe how these insights can be harnessed for therapeutic candidate development and translational.
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Affiliation(s)
- Ankit Garg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kory J. Lavine
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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4
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Moussaoui D, Robblee JP, Robert-Paganin J, Auguin D, Fisher F, Fagnant PM, Macfarlane JE, Schaletzky J, Wehri E, Mueller-Dieckmann C, Baum J, Trybus KM, Houdusse A. Mechanism of small molecule inhibition of Plasmodium falciparum myosin A informs antimalarial drug design. Nat Commun 2023; 14:3463. [PMID: 37308472 PMCID: PMC10261046 DOI: 10.1038/s41467-023-38976-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 05/24/2023] [Indexed: 06/14/2023] Open
Abstract
Malaria results in more than 500,000 deaths per year and the causative Plasmodium parasites continue to develop resistance to all known agents, including different antimalarial combinations. The class XIV myosin motor PfMyoA is part of a core macromolecular complex called the glideosome, essential for Plasmodium parasite mobility and therefore an attractive drug target. Here, we characterize the interaction of a small molecule (KNX-002) with PfMyoA. KNX-002 inhibits PfMyoA ATPase activity in vitro and blocks asexual blood stage growth of merozoites, one of three motile Plasmodium life-cycle stages. Combining biochemical assays and X-ray crystallography, we demonstrate that KNX-002 inhibits PfMyoA using a previously undescribed binding mode, sequestering it in a post-rigor state detached from actin. KNX-002 binding prevents efficient ATP hydrolysis and priming of the lever arm, thus inhibiting motor activity. This small-molecule inhibitor of PfMyoA paves the way for the development of alternative antimalarial treatments.
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Affiliation(s)
- Dihia Moussaoui
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, 75248, Paris, France
- Structural Biology group, European Synchrotron Radiation Facility (ESRF), 71, Avenue des Martyrs, 38000, Grenoble, France
| | - James P Robblee
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, VT, USA
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, 75248, Paris, France
| | - Daniel Auguin
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, 75248, Paris, France
- Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), Université d'Orléans, INRAE, USC1328, Orléans, France
| | - Fabio Fisher
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Patricia M Fagnant
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, VT, USA
| | - Jill E Macfarlane
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, VT, USA
| | - Julia Schaletzky
- Center for Emerging and Neglected Diseases, Drug Discovery Center, Berkeley, CA, USA
| | - Eddie Wehri
- Center for Emerging and Neglected Diseases, Drug Discovery Center, Berkeley, CA, USA
| | - Christoph Mueller-Dieckmann
- Structural Biology group, European Synchrotron Radiation Facility (ESRF), 71, Avenue des Martyrs, 38000, Grenoble, France
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
- School of Medical Sciences, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, 2052, Australia
| | - Kathleen M Trybus
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, VT, USA.
| | - Anne Houdusse
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, 75248, Paris, France.
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5
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Altered Left Ventricular Rat Gene Expression Induced by the Myosin Activator Omecamtiv Mecarbil. Genes (Basel) 2023; 14:genes14010122. [PMID: 36672863 PMCID: PMC9858687 DOI: 10.3390/genes14010122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/03/2023] Open
Abstract
To explore the impact of omecamtiv mecarbil (OM) on the gene expression profile in adult male rats. Fourteen male Wistar rats were randomly assigned to a single OM (1.2 mg/kg/h; n = 6) or placebo (n = 8) 30-min infusion. Echocardiography was performed before and after OM infusion. Seven days after infusion, rats were euthanized, and left ventricular (LV) tissues were removed for real-time quantitative polymerase chain reaction (RTq-PCR) experiments. After OM infusion, pro-apoptotic Bax-to-Bcl2 ratio was decreased, with increased Bcl2 and similar Bax gene expression. The gene expression of molecules regulating oxidative stress, including glutathione disulfide reductase (Gsr) and superoxide dismutases (Sod1/Sod2), remained unchanged, whereas the expression of antioxidant glutathione peroxidase (Gpx) increased. While LV gene expression of key energy sensors, peroxisome proliferator activator (Ppar) α and γ, AMP-activated protein kinase (Ampk), and carnitine palmitoyltransferase 1 (Cpt1) remained unchanged after OM infusion, and the expression of pyruvate dehydrogenase kinase 4 (Pdk4) increased. The LV expression of the major myocardial glucose transporter Glut1 decreased, with no changes in Glut4 expression, whereas the LV expression of oxidized low-density lipoprotein receptor 1 (Olr1) and arachidonate 15-lipoxygenase (Alox15) increased, with no changes in fatty acid transporter Cd36. An increased LV expression of angiotensin II receptors AT1 and AT2 was observed, with no changes in angiotensin I-converting enzyme expression. The Kalikrein-bradykinin system was upregulated with increased LV expression of kallikrein-related peptidases Klk8, Klk1c2, and Klk1c12 and bradykinin receptors B1 and B2 (Bdkrb1 and Bdkrb2), whereas the LV expression of inducible nitric oxide synthase 2 (Nos2) increased. LV expression in major molecular determinants involved in calcium-dependent myocardial contraction remained unchanged, except for an increased LV expression of calcium/calmodulin-dependent protein kinase II delta (Cacna1c) in response to OM. A single intravenous infusion of OM, in adult healthy rats, resulted in significant changes in the LV expression of genes regulating apoptosis, oxidative stress, metabolism, and cardiac contractility.
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Martin AA, Thompson BR, Hahn D, Angulski ABB, Hosny N, Cohen H, Metzger JM. Cardiac Sarcomere Signaling in Health and Disease. Int J Mol Sci 2022; 23:16223. [PMID: 36555864 PMCID: PMC9782806 DOI: 10.3390/ijms232416223] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
The cardiac sarcomere is a triumph of biological evolution wherein myriad contractile and regulatory proteins assemble into a quasi-crystalline lattice to serve as the central point upon which cardiac muscle contraction occurs. This review focuses on the many signaling components and mechanisms of regulation that impact cardiac sarcomere function. We highlight the roles of the thick and thin filament, both as necessary structural and regulatory building blocks of the sarcomere as well as targets of functionally impactful modifications. Currently, a new focus emerging in the field is inter-myofilament signaling, and we discuss here the important mediators of this mechanism, including myosin-binding protein C and titin. As the understanding of sarcomere signaling advances, so do the methods with which it is studied. This is reviewed here through discussion of recent live muscle systems in which the sarcomere can be studied under intact, physiologically relevant conditions.
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Affiliation(s)
| | | | | | | | | | | | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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Langa P, Wolska BM, Solaro RJ. The Hippo Signaling Pathway as a Drug Target in Familial Dilated Cardiomyopathy. INTERNATIONAL JOURNAL OF DRUG DISCOVERY AND PHARMACOLOGY 2022; 1:4. [PMID: 38818406 PMCID: PMC11139043 DOI: 10.53941/ijddp.v1i1.189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
We focus here on the Hippo pathway in the hierarchical sensing and modulation of the mechanical state of the adult heart in health and disease. The Hippo pathway interrogates the micro-environment of cardiac myocytes providing surveillance of the mechanical state with engagement of signaling pathways critical to homeostasis of cardiac development, remodeling, and function and vulnerable to pathologies. Our discussion centers on Hippo signaling in the altered mechanical state instigated by variants of genes expressing mutant sarcomere proteins that trigger a progression to dilated cardiomyopathy (familial DCM). There is an unmet need for therapies in DCM. Recent progress in the discovery of small molecules that target Hippo signaling and are intended for use in cardiac disorders provides leads for modifying Hippo in DCM. As we emphasize, identifying useful targets in DCM requires in depth understanding of cell specific Hippo signaling in the cardiac micro-environment.
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Affiliation(s)
- Paulina Langa
- Department of Physiology and Biophysics and the Center for Cardiovascular Research,University of Illinois at Chicago, Chicago, IL,USA
| | - Beata M. Wolska
- Department of Physiology and Biophysics and the Center for Cardiovascular Research,University of Illinois at Chicago, Chicago, IL,USA
- Department of Medicine, Division of Cardiology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - R. John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research,University of Illinois at Chicago, Chicago, IL,USA
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Forouzandehmehr M, Paci M, Koivumäki JT, Hyttinen J. Altered contractility in mutation-specific hypertrophic cardiomyopathy: A mechano-energetic in silico study with pharmacological insights. Front Physiol 2022; 13:1010786. [PMID: 36388127 PMCID: PMC9659818 DOI: 10.3389/fphys.2022.1010786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/14/2022] [Indexed: 07/25/2023] Open
Abstract
Introduction: Mavacamten (MAVA), Blebbistatin (BLEB), and Omecamtiv mecarbil (OM) are promising drugs directly targeting sarcomere dynamics, with demonstrated efficacy against hypertrophic cardiomyopathy (HCM) in (pre)clinical trials. However, the molecular mechanism affecting cardiac contractility regulation, and the diseased cell mechano-energetics are not fully understood yet. Methods: We present a new metabolite-sensitive computational model of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) electromechanics to investigate the pathology of R403Q HCM mutation and the effect of MAVA, BLEB, and OM on the cell mechano-energetics. Results: We offer a mechano-energetic HCM calibration of the model, capturing the prolonged contractile relaxation due to R403Q mutation (∼33%), without assuming any further modifications such as an additional Ca2+ flux to the thin filaments. The HCM model variant correctly predicts the negligible alteration in ATPase activity in R403Q HCM condition compared to normal hiPSC-CMs. The simulated inotropic effects of MAVA, OM, and BLEB, along with the ATPase activities in the control and HCM model variant agree with in vitro results from different labs. The proposed model recapitulates the tension-Ca2+ relationship and action potential duration change due to 1 µM OM and 5 µM BLEB, consistently with in vitro data. Finally, our model replicates the experimental dose-dependent effect of OM and BLEB on the normalized isometric tension. Conclusion: This work is a step toward deep-phenotyping the mutation-specific HCM pathophysiology, manifesting as altered interfilament kinetics. Accordingly, the modeling efforts lend original insights into the MAVA, BLEB, and OM contributions to a new interfilament balance resulting in a cardioprotective effect.
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Nakanishi T, Oyama K, Tanaka H, Kobirumaki-Shimozawa F, Ishii S, Terui T, Ishiwata S, Fukuda N. Effects of omecamtiv mecarbil on the contractile properties of skinned porcine left atrial and ventricular muscles. Front Physiol 2022; 13:947206. [PMID: 36082222 PMCID: PMC9445838 DOI: 10.3389/fphys.2022.947206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Omecamtiv mecarbil (OM) is a novel inotropic agent for heart failure with systolic dysfunction. OM prolongs the actomyosin attachment duration, which enhances thin filament cooperative activation and accordingly promotes the binding of neighboring myosin to actin. In the present study, we investigated the effects of OM on the steady-state contractile properties in skinned porcine left ventricular (PLV) and atrial (PLA) muscles. OM increased Ca2+ sensitivity in a concentration-dependent manner in PLV, by left shifting the mid-point (pCa50) of the force-pCa curve (ΔpCa50) by ∼0.16 and ∼0.33 pCa units at 0.5 and 1.0 μM, respectively. The Ca2+-sensitizing effect was likewise observed in PLA, but less pronounced with ΔpCa50 values of ∼0.08 and ∼0.22 pCa units at 0.5 and 1.0 μM, respectively. The Ca2+-sensitizing effect of OM (1.0 μM) was attenuated under enhanced thin filament cooperative activation in both PLV and PLA; this attenuation occurred directly via treatment with fast skeletal troponin (ΔpCa50: ∼0.16 and ∼0.10 pCa units in PLV and PLA, respectively) and indirectly by increasing the number of strongly bound cross-bridges in the presence of 3 mM MgADP (ΔpCa50: ∼0.21 and ∼0.08 pCa units in PLV and PLA, respectively). It is likely that this attenuation of the Ca2+-sensitizing effect of OM is due to a decrease in the number of “recruitable” cross-bridges that can potentially produce active force. When cross-bridge detachment was accelerated in the presence of 20 mM inorganic phosphate, the Ca2+-sensitizing effect of OM (1.0 μM) was markedly decreased in both types of preparations (ΔpCa50: ∼0.09 and ∼0.03 pCa units in PLV and PLA, respectively). The present findings suggest that the positive inotropy of OM is more markedly exerted in the ventricle than in the atrium, which results from the strongly bound cross-bridge-dependent allosteric activation of thin filaments.
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Affiliation(s)
- Tomohiro Nakanishi
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
- Department of Anesthesiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Kotaro Oyama
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
- Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology, Gunma, Japan
| | - Hiroyuki Tanaka
- Laboratory of Marine Biotechnology and Microbiology, Hokkaido University, Hakodate, Japan
| | | | - Shuya Ishii
- Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology, Gunma, Japan
| | - Takako Terui
- Department of Anesthesiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Shin’ichi Ishiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan
| | - Norio Fukuda
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
- *Correspondence: Norio Fukuda,
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Halas M, Langa P, Warren CM, Goldspink PH, Wolska BM, Solaro RJ. Effects of Sarcomere Activators and Inhibitors Targeting Myosin Cross-Bridges on Ca2+-Activation of Mature and Immature Mouse Cardiac Myofilaments. Mol Pharmacol 2022; 101:286-299. [PMID: 35236770 PMCID: PMC9092471 DOI: 10.1124/molpharm.121.000420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 02/16/2022] [Indexed: 11/22/2022] Open
Abstract
We tested the hypothesis that isoform shifts in sarcomeres of the immature heart modify the effect of cardiac myosin-directed sarcomere inhibitors and activators. Omecamtiv mecarbil (OM) activates tension and is in clinical trials for the treatment of adult acute and chronic heart failure. Mavacamten (Mava) inhibits tension and is in clinical trials to relieve hyper-contractility and outflow obstruction in advanced genetic hypertrophic cardiomyopathy (HCM) linked commonly to mutations in sarcomeric proteins. To address the effect of these agents in developing sarcomeres we isolated heart fiber bundles, extracted membranes with Triton X-100, and measured tension developed over a range of Ca2+ concentrations with and without OM or Mava treatment. We made measurements in fiber bundles from hearts of adult non-transgenic controls (NTG) expressing cardiac troponin I (cTnI), and from hearts of transgenic mice (TG-ssTnI) expressing the fetal/neonatal form, slow skeletal troponin I (ssTnI). We also compared fibers from 7+14-day-old NTG mice expressing ssTnI and cTnI. These studies were repeated with 7+14-day old transgenic mice (TG-cTnT-R92Q) expressing a mutant form of cardiac TnT (cTnT) linked to HCM. OM increased Ca2+-sensitivity and decreased cooperative activation in both ssTnI- and cTnI- regulated myofilaments with a similar effect reducing sub-maximal tension in immature and mature myofilaments. Although Mava decreased tension similarly in cTnI- and ssTnI-regulated myofilaments controlled either by cTnT or cTnT-R92Q, its effect involved a depressed Ca2+-sensitivity in the mature cTnT-R92-myofilaments. Our data demonstrate an influence of myosin and thin filament-associated proteins on the actions of myosin-directed agents such as OM and Mava. Significance Statement The effects of myosin-targeted activators and inhibitors on Ca2+-activated tension in developing cardiac sarcomeres presented here provide novel, ex-vivo evidence as to their actions in early-stage cardiac disorders. These studies advance understanding of the molecular mechanisms of these agents that is important in pre-clinical studies employing sarcomere Ca2+-response as a screening approach. The data also inform the use of commonly immature cardiac myocytes generated from human inducible pluripotent stem cells in screening for sarcomere activators and inhibitors.
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Affiliation(s)
- Monika Halas
- Physiology and Biophysics, University of Illinois at Chicago, United States
| | - Paulina Langa
- Physiology and Biophysics, University of Illinois at Chicago, United States
| | - Chad M Warren
- Physiology and Biophysics, University of Illinois at Chicago, United States
| | - Paul H Goldspink
- Physiology and Biophysics, University of Illinois at Chicago, United States
| | - Beata M Wolska
- Department of Medicine, University of Illinois at Chicago, United States
| | - R John Solaro
- Physiology and Biophysics, University of Illinois at Chicago, United States
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11
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Parker LE, Landstrom AP. The clinical utility of pediatric cardiomyopathy genetic testing: From diagnosis to a precision medicine-based approach to care. PROGRESS IN PEDIATRIC CARDIOLOGY 2021; 62. [PMID: 34776723 DOI: 10.1016/j.ppedcard.2021.101413] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background Pediatric-onset cardiomyopathies are rare yet cause significant morbidity and mortality in affected children. Genetic testing has a major role in the clinical evaluation of pediatric-onset cardiomyopathies, and identification of a variant in an associated gene can be used to confirm the clinical diagnosis and exclude syndromic causes that may warrant different treatment strategies. Further, risk-predictive testing of first-degree relatives can assess who is at-risk of disease and requires continued clinical follow-up. Aim of Review In this review, we seek to describe the current role of genetic testing in the clinical diagnosis and management of patients and families with the five major cardiomyopathies. Further, we highlight the ongoing development of precision-based approaches to diagnosis, prognosis, and treatment. Key Scientific Concepts of Review Emerging application of genotype-phenotype correlations opens the door for genetics to guide a precision medicine-based approach to prognosis and potentially for therapies. Despite advances in our understanding of the genetic etiology of cardiomyopathy and increased accessibility of clinical genetic testing, not all pediatric cardiomyopathy patients have a clear genetic explanation for their disease. Expanded genomic studies are needed to understand the cause of disease in these patients, improve variant classification and genotype-driven prognostic predictions, and ultimately develop truly disease preventing treatment.
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Affiliation(s)
- Lauren E Parker
- Department of Pediatrics, Division of Cardiology, Duke University School of Medicine, Durham, NC, United States
| | - Andrew P Landstrom
- Department of Pediatrics, Division of Cardiology, Duke University School of Medicine, Durham, NC, United States.,Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States
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12
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Lertwanakarn T, Suntravat M, Sánchez EE, Wolska BM, Solaro RJ, de Tombe PP, Tachampa K. Negative inotropic mechanisms of β-cardiotoxin in cardiomyocytes by depression of myofilament ATPase activity without activation of the classical β-adrenergic pathway. Sci Rep 2021; 11:21154. [PMID: 34707114 PMCID: PMC8551325 DOI: 10.1038/s41598-021-00282-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/06/2021] [Indexed: 11/09/2022] Open
Abstract
Beta-cardiotoxin (β-CTX) from the king cobra venom (Ophiophagus hannah) was previously proposed as a novel β-adrenergic blocker. However, the involvement of β-adrenergic signaling by this compound has never been elucidated. The objectives of this study were to investigate the underlying mechanisms of β-CTX as a β-blocker and its association with the β-adrenergic pathway. The effects of β-CTX on isolated cardiac myocyte functions, calcium homeostasis, the phosphorylation level of targeted proteins, and the myofibrillar ATPase activity were studied. Healthy Sprague Dawley rats were used for cardiomyocytes isolation. Like propranolol, β-CTX attenuated the cardiomyocyte inotropy and calcium transient alterations as induced by isoproterenol stimulation. In contrast, these effects were not observed in forskolin-treated cells. Interestingly, cardiomyocytes treated with β-CTX showed no changes in phosphorylation level at any PKA-targeted sites in the myofilaments as demonstrated in Western blot analysis. The skinned fibers study revealed no change in myofilament kinetics by β-CTX. However, this protein exhibited the direct inhibition of myofibrillar ATPase activity with calcium de-sensitization of the enzyme. In summary, the negative inotropic mechanism of β-CTX was discovered. β-CTX exhibits an atypical β-blocker mechanism. These properties of β-CTX may benefit in developing a novel agent aid to treat hypertrophic cardiomyopathy.
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Affiliation(s)
- Tuchakorn Lertwanakarn
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Montamas Suntravat
- National Natural Toxins Research Center, Texas-A&M University-Kingsville, Kingsville, TX, USA.,Department of Chemistry, Texas A&M University-Kingsville, Kingsville, TX, USA
| | - Elda E Sánchez
- National Natural Toxins Research Center, Texas-A&M University-Kingsville, Kingsville, TX, USA.,Department of Chemistry, Texas A&M University-Kingsville, Kingsville, TX, USA
| | - Beata M Wolska
- Department of Physiology and Biophysics, the University of Illinois at Chicago, Chicago, IL, USA.,Department of Medicine, the University of Illinois at Chicago, Chicago, IL, USA
| | - R John Solaro
- Department of Physiology and Biophysics, the University of Illinois at Chicago, Chicago, IL, USA
| | - Pieter P de Tombe
- Department of Physiology and Biophysics, the University of Illinois at Chicago, Chicago, IL, USA.,Phymedexp, Université de Montpellier, Inserm, CNRS, Montpellier, France
| | - Kittipong Tachampa
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
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13
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Lookin O, Kuznetsov D, Protsenko Y. Omecamtiv mecarbil attenuates length-tension relationship in healthy rat myocardium and preserves it in monocrotaline-induced pulmonary heart failure. Clin Exp Pharmacol Physiol 2021; 49:84-93. [PMID: 34459025 DOI: 10.1111/1440-1681.13584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 01/10/2023]
Abstract
The cardiac-specific myosin activator, omecamtiv mecarbil (OM), is an effective inotrope for treating heart failure but its effects on active force and Ca2+ kinetics in healthy and diseased myocardium remain poorly studied. We tested the effect of two concentrations of OM (0.2 and 1 µmol/L in saline) on isometric contraction and Ca-transient (CaT) in right ventricular trabeculae of healthy rats (CONT, n = 8) and rats with monocrotaline-induced pulmonary heart failure (MCT, n = 8). The contractions were obtained under preload of 75%-100% of optimal length (tension-length relationship). The 0.2 µmol/L OM did not affect the diastolic level, amplitude, or kinetics of isometric contraction and CaT, irrespective of the group of rats or preload. The 1 µmol/L OM significantly suppressed active tension-length relationships in CONT but not in MCT, while leading in both groups to a significantly prolonged relaxation. CaT time-to-peak was unaffected in CONT and MCT, but CaT decay was slightly accelerated in its early phase and considerably prolonged in its late phase to a similar extent in both groups. We conclude that the substantial prolongation of CaT decay is due to enhanced Ca2+ utilisation by troponin C mediated by the direct effect of OM on the cooperative activation of myofilaments. The lack of beneficial effect of OM in the healthy rat myocardium may be due to a relatively high level of activating Ca2+ in cells with normal Ca2+ handling, whereas the preservation of the tension-length relationship in the failing heart may relate to the diminished Ca2+ levels of sarcoplasmic reticulum.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Daniil Kuznetsov
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Yuri Protsenko
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
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14
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Joumaa V, Fukutani A, Herzog W. Energy Cost of Force Production After a Stretch-Shortening Cycle in Skinned Muscle Fibers: Does Muscle Efficiency Increase? Front Physiol 2021; 11:567538. [PMID: 33536930 PMCID: PMC7848195 DOI: 10.3389/fphys.2020.567538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 12/23/2020] [Indexed: 12/26/2022] Open
Abstract
Muscle force is enhanced during shortening when shortening is preceded by an active stretch. This phenomenon is known as the stretch-shortening cycle (SSC) effect. For some stretch-shortening conditions this increase in force during shortening is maintained following SSCs when compared to the force following a pure shortening contraction. It has been suggested that the residual force enhancement property of muscles, which comes into play during the stretch phase of SSCs may contribute to the force increase after SSCs. Knowing that residual force enhancement is associated with a substantial reduction in metabolic energy per unit of force, it seems reasonable to assume that the metabolic energy cost per unit of force is also reduced following a SSC. The purpose of this study was to determine the energy cost per unit of force at steady-state following SSCs and compare it to the corresponding energy cost following pure shortening contractions of identical speed and magnitude. We hypothesized that the energy cost per unit of muscle force is reduced following SSCs compared to the pure shortening contractions. For the SSC tests, rabbit psoas fibers (n = 12) were set at an average sarcomere length (SL) of 2.4 μm, activated, actively stretched to a SL of 3.2 μm, and shortened to a SL of 2.6 or 3.0 μm. For the pure shortening contractions, the same fibers were activated at a SL of 3.2 μm and actively shortened to a SL of 2.6 or 3.0 μm. The amount of ATP consumed was measured over a 40 s steady-state total isometric force following either the SSCs or the pure active shortening contractions. Fiber stiffness was determined in an additional set of 12 fibers, at steady-state for both experimental conditions. Total force, ATP consumption, and stiffness were greater following SSCs compared to the pure shortening contractions, but ATP consumption per unit of force was the same between conditions. These results suggest that the increase in total force observed following SSCs was achieved with an increase in the proportion of attached cross-bridges and titin stiffness. We conclude that muscle efficiency is not enhanced at steady-state following SSCs.
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Affiliation(s)
- Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Atsuki Fukutani
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Biomechanics Laboratory, School of Sports, Federal University of Santa Catarina, Florianopolis, Brazil
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15
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Maack C, Eschenhagen T, Hamdani N, Heinzel FR, Lyon AR, Manstein DJ, Metzger J, Papp Z, Tocchetti CG, Yilmaz MB, Anker SD, Balligand JL, Bauersachs J, Brutsaert D, Carrier L, Chlopicki S, Cleland JG, de Boer RA, Dietl A, Fischmeister R, Harjola VP, Heymans S, Hilfiker-Kleiner D, Holzmeister J, de Keulenaer G, Limongelli G, Linke WA, Lund LH, Masip J, Metra M, Mueller C, Pieske B, Ponikowski P, Ristić A, Ruschitzka F, Seferović PM, Skouri H, Zimmermann WH, Mebazaa A. Treatments targeting inotropy. Eur Heart J 2020; 40:3626-3644. [PMID: 30295807 DOI: 10.1093/eurheartj/ehy600] [Citation(s) in RCA: 113] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/06/2018] [Accepted: 09/14/2018] [Indexed: 02/06/2023] Open
Abstract
Acute heart failure (HF) and in particular, cardiogenic shock are associated with high morbidity and mortality. A therapeutic dilemma is that the use of positive inotropic agents, such as catecholamines or phosphodiesterase-inhibitors, is associated with increased mortality. Newer drugs, such as levosimendan or omecamtiv mecarbil, target sarcomeres to improve systolic function putatively without elevating intracellular Ca2+. Although meta-analyses of smaller trials suggested that levosimendan is associated with a better outcome than dobutamine, larger comparative trials failed to confirm this observation. For omecamtiv mecarbil, Phase II clinical trials suggest a favourable haemodynamic profile in patients with acute and chronic HF, and a Phase III morbidity/mortality trial in patients with chronic HF has recently begun. Here, we review the pathophysiological basis of systolic dysfunction in patients with HF and the mechanisms through which different inotropic agents improve cardiac function. Since adenosine triphosphate and reactive oxygen species production in mitochondria are intimately linked to the processes of excitation-contraction coupling, we also discuss the impact of inotropic agents on mitochondrial bioenergetics and redox regulation. Therefore, this position paper should help identify novel targets for treatments that could not only safely improve systolic and diastolic function acutely, but potentially also myocardial structure and function over a longer-term.
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Affiliation(s)
- Christoph Maack
- Comprehensive Heart Failure Center, University Clinic Würzburg, Am Schwarzenberg 15, Würzburg, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,Partner site Hamburg/Kiel/Lübeck, DZHK (German Centre for Cardiovascular Research), Hamburg, Germany
| | - Nazha Hamdani
- Department of Cardiovascular Physiology, Ruhr University Bochum, Bochum, Germany
| | - Frank R Heinzel
- Department of Cardiology, Charité University Medicine, Berlin, Germany
| | - Alexander R Lyon
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital and National Heart and Lung Institute, Imperial College, London, UK
| | - Dietmar J Manstein
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany.,Division for Structural Biochemistry, Hannover Medical School, Hannover, Germany
| | - Joseph Metzger
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Zoltán Papp
- Division of Clinical Physiology, Department of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Carlo G Tocchetti
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - M Birhan Yilmaz
- Department of Cardiology, Cumhuriyet University, Sivas, Turkey
| | - Stefan D Anker
- Department of Cardiology and Pneumology, University Medical Center Göttingen and DZHK (German Center for Cardiovascular Research), Göttingen, Germany.,Division of Cardiology and Metabolism - Heart Failure, Cachexia and Sarcopenia, Department of Internal Medicine and Cardiology, Berlin-Brandenburg Center for Regenerative Therapies (BCRT) at Charité University Medicine, Berlin, Germany
| | - Jean-Luc Balligand
- Institut de Recherche Expérimentale et Clinique (IREC), Pole of Pharmacology and Therapeutics (FATH), Universite Catholique de Louvain and Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Johann Bauersachs
- Department of Cardiology and Angiology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover D-30625, Germany
| | | | - Lucie Carrier
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,Partner site Hamburg/Kiel/Lübeck, DZHK (German Centre for Cardiovascular Research), Hamburg, Germany
| | - Stefan Chlopicki
- Department of Pharmacology, Medical College, Jagiellonian University, Krakow, Poland
| | - John G Cleland
- University of Hull, Kingston upon Hull, UK.,National Heart and Lung Institute, Royal Brompton and Harefield Hospitals NHS Trust, Imperial College, London, UK
| | - Rudolf A de Boer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Alexander Dietl
- Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany
| | - Rodolphe Fischmeister
- Inserm UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | | | | | | | | | - Gilles de Keulenaer
- Laboratory of Physiopharmacology (University of Antwerp) and Department of Cardiology, ZNA Hospital, Antwerp, Belgium
| | - Giuseppe Limongelli
- Department of Cardiothoracic Sciences, Second University of Naples, Naples, Italy
| | | | - Lars H Lund
- Division of Cardiology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Josep Masip
- Intensive Care Department, Consorci Sanitari Integral, University of Barcelona, Spain
| | - Marco Metra
- Cardiology, Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, University of Brescia, Italy
| | - Christian Mueller
- Department of Cardiology and Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, University of Basel, Switzerland
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Center Berlin, and German Centre for Cardiovascular Research (DZHK), Partner site Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Piotr Ponikowski
- Department of Cardiology, Medical University, Clinical Military Hospital, Wroclaw, Poland
| | - Arsen Ristić
- Department of Cardiology of the Clinical Center of Serbia and Belgrade University School of Medicine, Belgrade, Serbia
| | - Frank Ruschitzka
- Department of Cardiology, University Heart Centre, University Hospital Zurich, Switzerland
| | | | - Hadi Skouri
- Division of Cardiology, American University of Beirut Medical Centre, Beirut, Lebanon
| | - Wolfram H Zimmermann
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK), Partner siteGöttingen, Göttingen, Germany
| | - Alexandre Mebazaa
- Hôpital Lariboisière, Université Paris Diderot, Inserm U 942, Paris, France
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16
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Powers JD, Kooiker KB, Mason AB, Teitgen AE, Flint GV, Tardiff JC, Schwartz SD, McCulloch AD, Regnier M, Davis J, Moussavi-Harami F. Modulating the tension-time integral of the cardiac twitch prevents dilated cardiomyopathy in murine hearts. JCI Insight 2020; 5:142446. [PMID: 32931484 PMCID: PMC7605524 DOI: 10.1172/jci.insight.142446] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/09/2020] [Indexed: 12/13/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is often associated with sarcomere protein mutations that confer reduced myofilament tension–generating capacity. We demonstrated that cardiac twitch tension-time integrals can be targeted and tuned to prevent DCM remodeling in hearts with contractile dysfunction. We employed a transgenic murine model of DCM caused by the D230N-tropomyosin (Tm) mutation and designed a sarcomere-based intervention specifically targeting the twitch tension-time integral of D230N-Tm hearts using multiscale computational models of intramolecular and intermolecular interactions in the thin filament and cell-level contractile simulations. Our models predicted that increasing the calcium sensitivity of thin filament activation using the cardiac troponin C (cTnC) variant L48Q can sufficiently augment twitch tension-time integrals of D230N-Tm hearts. Indeed, cardiac muscle isolated from double-transgenic hearts expressing D230N-Tm and L48Q cTnC had increased calcium sensitivity of tension development and increased twitch tension-time integrals compared with preparations from hearts with D230N-Tm alone. Longitudinal echocardiographic measurements revealed that DTG hearts retained normal cardiac morphology and function, whereas D230N-Tm hearts developed progressive DCM. We present a computational and experimental framework for targeting molecular mechanisms governing the twitch tension of cardiomyopathic hearts to counteract putative mechanical drivers of adverse remodeling and open possibilities for tension-based treatments of genetic cardiomyopathies. Tuning the molecular mechanisms that govern the twitch tension of cardiomyopathic hearts counteracts mechanical drivers of adverse remodeling.
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Affiliation(s)
- Joseph D Powers
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA.,Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA
| | - Kristina B Kooiker
- Division of Cardiology, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Allison B Mason
- Department of Chemistry and Biochemistry, College of Science, and
| | - Abigail E Teitgen
- Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA
| | - Galina V Flint
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA
| | - Jil C Tardiff
- Department of Biomedical Engineering, College of Engineering, University of Arizona, Tucson, Arizona, USA
| | | | - Andrew D McCulloch
- Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA.,Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Michael Regnier
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA
| | - Jennifer Davis
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA.,Department of Laboratory Medicine & Pathology, University of Washington, Seattle, Washington, USA
| | - Farid Moussavi-Harami
- Division of Cardiology, School of Medicine, University of Washington, Seattle, Washington, USA
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17
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Robinson P, Sparrow AJ, Patel S, Malinowska M, Reilly SN, Zhang YH, Casadei B, Watkins H, Redwood C. Dilated cardiomyopathy mutations in thin-filament regulatory proteins reduce contractility, suppress systolic Ca 2+, and activate NFAT and Akt signaling. Am J Physiol Heart Circ Physiol 2020; 319:H306-H319. [PMID: 32618513 PMCID: PMC7473929 DOI: 10.1152/ajpheart.00272.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Dilated cardiomyopathy (DCM) is clinically characterized by dilated ventricular cavities and reduced ejection fraction, leading to heart failure and increased thromboembolic risk. Mutations in thin-filament regulatory proteins can cause DCM and have been shown in vitro to reduce contractility and myofilament Ca2+-affinity. In this work we have studied the functional consequences of mutations in cardiac troponin T (R131W), cardiac troponin I (K36Q) and α-tropomyosin (E40K) using adenovirally transduced isolated guinea pig left ventricular cardiomyocytes. We find significantly reduced fractional shortening with reduced systolic Ca2+. Contraction and Ca2+ reuptake times were slowed, which contrast with some findings in murine models of myofilament Ca2+ desensitization. We also observe increased sarcoplasmic reticulum (SR) Ca2+ load and smaller fractional SR Ca2+ release. This corresponds to a reduction in SR Ca2+-ATPase activity and increase in sodium-calcium exchanger activity. We also observe dephosphorylation and nuclear translocation of the nuclear factor of activated T cells (NFAT), with concordant RAC-α-serine/threonine protein kinase (Akt) phosphorylation but no change to extracellular signal-regulated kinase activation in chronically paced cardiomyocytes expressing DCM mutations. These changes in Ca2+ handling and signaling are common to all three mutations, indicating an analogous pathway of disease pathogenesis in thin-filament sarcomeric DCM. Previous work has shown that changes to myofilament Ca2+ sensitivity caused by DCM mutations are qualitatively opposite from hypertrophic cardiomyopathy (HCM) mutations in the same genes. However, we find several common pathways such as increased relaxation times and NFAT activation that are also hallmarks of HCM. This suggests more complex intracellular signaling underpinning DCM, driven by the primary mutation.NEW & NOTEWORTHY Dilated cardiomyopathy (DCM) is a frequently occurring cardiac disorder with a degree of genetic inheritance. We have found that DCM mutations in proteins that regulate the contractile machinery cause alterations to contraction, calcium-handling, and some new signaling pathways that provide stimuli for disease development. We have used guinea pig cells that recapitulate human calcium-handling and introduced the mutations using adenovirus gene transduction to look at the initial triggers of disease before remodeling.
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Affiliation(s)
- Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Alexander J Sparrow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Suketu Patel
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Marta Malinowska
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Svetlana N Reilly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Yin-Hua Zhang
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Barbara Casadei
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Charles Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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18
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Muir WW, Hamlin RL. Myocardial Contractility: Historical and Contemporary Considerations. Front Physiol 2020; 11:222. [PMID: 32296340 PMCID: PMC7137917 DOI: 10.3389/fphys.2020.00222] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 02/26/2020] [Indexed: 12/17/2022] Open
Abstract
The term myocardial contractility is thought to have originated more than 125 years ago and has remained and enigma ever since. Although the term is frequently used in textbooks, editorials and contemporary manuscripts its definition remains illusive often being conflated with cardiac performance or inotropy. The absence of a universally accepted definition has led to confusion, disagreement and misconceptions among physiologists, cardiologists and safety pharmacologists regarding its definition particularly in light of new discoveries regarding the load dependent kinetics of cardiac contraction and their translation to cardiac force-velocity and ventricular pressure-volume measurements. Importantly, the Starling interpretation of force development is length-dependent while contractility is length independent. Most historical definitions employ an operational approach and define cardiac contractility in terms of the hearts mechanical properties independent of loading conditions. Literally defined the term contract infers that something has become smaller, shrunk or shortened. The addition of the suffix “ility” implies the quality of this process. The discovery and clinical investigation of small molecules that bind to sarcomeric proteins independently altering force or velocity requires that a modern definition of the term myocardial contractility be developed if the term is to persist. This review reconsiders the historical and contemporary interpretations of the terms cardiac performance and inotropy and recommends a modern definition of myocardial contractility as the preload, afterload and length-independent intrinsic kinetically controlled, chemo-mechanical processes responsible for the development of force and velocity.
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Affiliation(s)
- William W Muir
- College of Veterinary Medicine, Lincoln Memorial University, Harrogate, TN, United States
| | - Robert L Hamlin
- College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States
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19
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Lindqvist J, Lee EJ, Karimi E, Kolb J, Granzier H. Omecamtiv mecarbil lowers the contractile deficit in a mouse model of nebulin-based nemaline myopathy. PLoS One 2019; 14:e0224467. [PMID: 31721788 PMCID: PMC6853306 DOI: 10.1371/journal.pone.0224467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 10/14/2019] [Indexed: 01/10/2023] Open
Abstract
Nemaline myopathy (NEM) is a congenital neuromuscular disorder primarily caused by nebulin gene (NEB) mutations. NEM is characterized by muscle weakness for which currently no treatments exist. In NEM patients a predominance of type I fibers has been found. Thus, therapeutic options targeting type I fibers could be highly beneficial for NEM patients. Because type I muscle fibers express the same myosin isoform as cardiac muscle (Myh7), the effect of omecamtiv mecarbil (OM), a small molecule activator of Myh7, was studied in a nebulin-based NEM mouse model (Neb cKO). Skinned single fibers were activated by exogenous calcium and force was measured at a wide range of calcium concentrations. Maximal specific force of type I fibers was much less in fibers from Neb cKO animals and calcium sensitivity of permeabilized single fibers was reduced (pCa50 6.12 ±0.08 (cKO) vs 6.36 ±0.08 (CON)). OM increased the calcium sensitivity of type I single muscle fibers. The greatest effect occurred in type I fibers from Neb cKO muscle where OM restored the calcium sensitivity to that of the control type I fibers. Forces at submaximal activation levels (pCa 6.0–6.5) were significantly increased in Neb cKO fibers (~50%) but remained below that of control fibers. OM also increased isometric force and power during isotonic shortening of intact whole soleus muscle of Neb cKO mice, with the largest effects at physiological stimulation frequencies. We conclude that OM has the potential to improve the quality of life of NEM patients by increasing the force of type I fibers at submaximal activation levels.
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Affiliation(s)
- Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Eun-Jeong Lee
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Esmat Karimi
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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20
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Kiaie N, Emami SH, Rabbani S, Aghdam RM, Tafti HA. Targeted and Controlled Drug Delivery to a Rat Model of Heart Failure Through a Magnetic Nanocomposite. Ann Biomed Eng 2019; 48:709-721. [PMID: 31696331 DOI: 10.1007/s10439-019-02394-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 10/25/2019] [Indexed: 01/03/2023]
Abstract
As a novel cardiac myosin activator, Omecamtive Mecarbil (OM) has shown promising results in the management of systolic heart failure in clinical examinations. However, the need for repeated administration along with dose-dependent side effects made its use elusive as a standard treatment for heart failure (HF). We hypothesized that improved cardiac function in systolic HF models would be achieved in lower doses by targeted delivery of OM to the heart. To test this hypothesis, a nanocomposite system was developed by composing chitosan and a magnetic core (Fe3O4), loaded with OM, and directed toward the rats' heart via a 0.3 T magnet. HF-induced rats were injected with saline, OM, and OM-loaded nanocomposite (n = 8 in each group) and compared with a group of healthy animals (saline injected, n = 8). Knowing the ejection fraction (EF) of healthy (93.68 ± 1.37%) and HF (71.7 ± 1.41%) rats, injection of nanocomposites was associated with improved EF (EF = 89.6 ± 1.40%). Due to increased heart targeting of nanocomposite (2.5 folds), improved cardiac function was seen with only 4% of the OM dose required for infusion, while injecting the same dose of OM without targeting was unable to stop HF progression (EF = 55.33 ± 3.16%) during 7 days. In conclusion, heart nanocomposites targeting improves the EF by up to 18% by only using 4% of the doses traditionally used in treating the HF.
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Affiliation(s)
- Nasim Kiaie
- Department of Tissue Engineering, Amirkabir University of Technology, Tehran, Iran
| | | | - Shahram Rabbani
- Research Center for Advanced Technologies in Cardiovascular Medicine, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Hossein Ahmadi Tafti
- Research Center for Advanced Technologies in Cardiovascular Medicine, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
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21
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Tang W, Unrath WC, Desetty R, Yengo CM. Dilated cardiomyopathy mutation in the converter domain of human cardiac myosin alters motor activity and response to omecamtiv mecarbil. J Biol Chem 2019; 294:17314-17325. [PMID: 31578282 DOI: 10.1074/jbc.ra119.010217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/27/2019] [Indexed: 12/14/2022] Open
Abstract
We investigated a dilated cardiomyopathy (DCM) mutation (F764L) in human β-cardiac myosin by determining its motor properties in the presence and absence of the heart failure drug omecamtive mecarbil (OM). The mutation is located in the converter domain, a key region of communication between the catalytic motor and lever arm in myosins, and is nearby but not directly in the OM-binding site. We expressed and purified human β-cardiac myosin subfragment 1 (M2β-S1) containing the F764L mutation, and compared it to WT with in vitro motility as well as steady-state and transient kinetics measurements. In the absence of OM we demonstrate that the F764L mutation does not significantly change maximum actin-activated ATPase activity but slows actin sliding velocity (15%) and the actomyosin ADP release rate constant (25%). The transient kinetic analysis without OM demonstrates that F764L has a similar duty ratio as WT in unloaded conditions. OM is known to enhance force generation in cardiac muscle while it inhibits the myosin power stroke and enhances actin-attachment duration. We found that OM has a reduced impact on F764L ATPase and sliding velocity compared with WT. Specifically, the EC50 for OM induced inhibition of in vitro motility was 3-fold weaker in F764L. Also, OM reduces maximum actin-activated ATPase 2-fold in F764L, compared with 4-fold with WT. Overall, our results suggest that F764L attenuates the impact of OM on actin-attachment duration and/or the power stroke. Our work highlights the importance of mutation-specific considerations when pursuing small molecule therapies for cardiomyopathies.
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Affiliation(s)
- Wanjian Tang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - William C Unrath
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Rohini Desetty
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
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22
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Ma X, Dewan S, Liu J, Tang M, Miller KL, Yu C, Lawrence N, McCulloch AD, Chen S. 3D printed micro-scale force gauge arrays to improve human cardiac tissue maturation and enable high throughput drug testing. Acta Biomater 2019; 95:319-327. [PMID: 30576862 PMCID: PMC6584548 DOI: 10.1016/j.actbio.2018.12.026] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 12/11/2018] [Accepted: 12/17/2018] [Indexed: 12/20/2022]
Abstract
Human induced pluripotent stem cell - derived cardiomyocytes (iPSC-CMs) are regarded as a promising cell source for establishing in-vitro personalized cardiac tissue models and developing therapeutics. However, analyzing cardiac force and drug response using mature human iPSC-CMs in a high-throughput format still remains a great challenge. Here we describe a rapid light-based 3D printing system for fabricating micro-scale force gauge arrays suitable for 24-well and 96-well plates that enable scalable tissue formation and measurement of cardiac force generation in human iPSC-CMs. We demonstrate consistent tissue band formation around the force gauge pillars with aligned sarcomeres. Among the different maturation treatment protocols we explored, 3D aligned cultures on force gauge arrays with in-culture pacing produced the highest expression of mature cardiac marker genes. We further demonstrated the utility of these micro-tissues to develop significantly increased contractile forces in response to treatment with isoproterenol, levosimendan, and omecamtiv mecarbil. Overall, this new 3D printing system allows for high flexibility in force gauge design and can be optimized to achieve miniaturization and promote cardiac tissue maturation with great potential for high-throughput in-vitro drug screening applications. STATEMENT OF SIGNIFICANCE: The application of iPSC-derived cardiac tissues in translatable drug screening is currently limited by the challenges in forming mature cardiac tissue and analyzing cardiac forces in a high-throughput format. We demonstrate the use of a rapid light-based 3D printing system to build a micro-scale force gauge array that enables scalable cardiac tissue formation from iPSC-CMs and measurement of contractile force development. With the capability to provide great flexibility over force gauge design as well as optimization to achieve miniaturization, our 3D printing system serves as a promising tool to build cardiac tissues for high-throughput in-vitro drug screening applications.
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Affiliation(s)
- Xuanyi Ma
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Sukriti Dewan
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Justin Liu
- Department of Materials Science and Engineering Program, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Min Tang
- Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Kathleen L Miller
- Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Claire Yu
- Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Natalie Lawrence
- Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Shaochen Chen
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Materials Science and Engineering Program, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Chemical Engineering Program, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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23
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Verdonschot JAJ, Hazebroek MR, Ware JS, Prasad SK, Heymans SRB. Role of Targeted Therapy in Dilated Cardiomyopathy: The Challenging Road Toward a Personalized Approach. J Am Heart Assoc 2019; 8:e012514. [PMID: 31433726 PMCID: PMC6585365 DOI: 10.1161/jaha.119.012514] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Job A. J. Verdonschot
- Department of CardiologyCARIMMaastricht University Medical CentreMaastrichtThe Netherlands
- Department of Clinical GeneticsMaastricht University Medical CentreMaastrichtThe Netherlands
| | - Mark R. Hazebroek
- Department of CardiologyCARIMMaastricht University Medical CentreMaastrichtThe Netherlands
| | - James S. Ware
- Cardiovascular Research CentreRoyal Brompton & Harefield Hospitals NHS TrustLondonUnited Kingdom
- National Heart and Lung InstituteImperial College LondonLondonUnited Kingdom
- London Institute of Medical SciencesImperial College LondonLondonUnited Kingdom
| | - Sanjay K. Prasad
- Cardiovascular Research CentreRoyal Brompton & Harefield Hospitals NHS TrustLondonUnited Kingdom
- National Heart and Lung InstituteImperial College LondonLondonUnited Kingdom
| | - Stephane R. B. Heymans
- Department of CardiologyCARIMMaastricht University Medical CentreMaastrichtThe Netherlands
- Netherlands Heart InstituteUtrechtthe Netherlands
- Department of Cardiovascular ResearchUniversity of LeuvenBelgium
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24
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Kislitsina ON, Rich JD, Wilcox JE, Pham DT, Churyla A, Vorovich EB, Ghafourian K, Yancy CW. Shock - Classification and Pathophysiological Principles of Therapeutics. Curr Cardiol Rev 2019; 15:102-113. [PMID: 30543176 PMCID: PMC6520577 DOI: 10.2174/1573403x15666181212125024] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 10/11/2018] [Accepted: 12/10/2018] [Indexed: 01/10/2023] Open
Abstract
The management of patients with shock is extremely challenging because of the myriad of possible clinical presentations in cardiogenic shock, septic shock and hypovolemic shock and the limitations of contemporary therapeutic options. The treatment of shock includes the administration of endogenous catecholamines (epinephrine, norepinephrine, and dopamine) as well as various vasopressor agents that have shown efficacy in the treatment of the various types of shock. In addition to the endogenous catecholamines, dobutamine, isoproterenol, phenylephrine, and milrinone have served as the mainstays of shock therapy for several decades. Recently, experimental studies have suggested that newer agents such as vasopressin, selepressin, calcium-sensitizing agents like levosimendan, cardiac-specific myosin activators like omecamtiv mecarbil (OM), istaroxime, and natriuretic peptides like nesiritide can enhance shock therapy, especially when shock presents a more complex clinical picture than normal. However, their ability to improve clinical outcomes remains to be proven. It is the purpose of this review to describe the mechanism of action, dosage requirements, advantages and disadvantages, and specific indications and contraindications for the use of each of these catecholamines and vasopressors, as well as to elucidate the most important clinical trials that serve as the basis of contemporary shock therapy.
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Affiliation(s)
- Olga N Kislitsina
- Department of Cardiac Surgery Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States.,Department of Cardiology Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Jonathan D Rich
- Department of Cardiology Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Jane E Wilcox
- Department of Cardiology Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Duc T Pham
- Department of Cardiac Surgery Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Andrei Churyla
- Department of Cardiac Surgery Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Esther B Vorovich
- Department of Cardiology Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Kambiz Ghafourian
- Department of Cardiology Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
| | - Clyde W Yancy
- Department of Cardiology Bluhm Cardiovascular Institute Feinberg School of Medicine Northwestern University Medical Center, Chicago, Illinois, IL, United States
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25
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Dieseldorff Jones KM, Koh Y, Weller RS, Turna RS, Ahmad F, Huke S, Knollmann BC, Pinto JR, Hwang HS. Pathogenic troponin T mutants with opposing effects on myofilament Ca 2+ sensitivity attenuate cardiomyopathy phenotypes in mice. Arch Biochem Biophys 2018; 661:125-131. [PMID: 30445044 DOI: 10.1016/j.abb.2018.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 08/28/2018] [Accepted: 11/08/2018] [Indexed: 01/14/2023]
Abstract
Mutations in cardiac troponin T (TnT) associated with hypertrophic cardiomyopathy generally lead to an increase in the Ca2+ sensitivity of contraction and susceptibility to arrhythmias. In contrast, TnT mutations linked to dilated cardiomyopathy decrease the Ca2+ sensitivity of contraction. Here we tested the hypothesis that two TnT disease mutations with opposite effects on myofilament Ca2+ sensitivity can attenuate each other's phenotype. We crossed transgenic mice expressing the HCM TnT-I79N mutation (I79N) with a DCM knock-in mouse model carrying the heterozygous TnT-R141W mutation (HET). The results of the Ca2+ sensitivity in skinned cardiac muscle preparations ranked from highest to lowest were as follow: I79N > I79N/HET > NTg > HET. Echocardiographic measurements revealed an improvement in hemodynamic parameters in I79N/HET compared to I79N and normalization of left ventricular dimensions and volumes compared to both I79N and HET. Ex vivo testing showed that the I79N/HET mouse hearts had reduced arrhythmia susceptibility compared to I79N mice. These results suggest that two disease mutations in TnT that have opposite effects on the myofilament Ca2+ sensitivity can paradoxically ameliorate each other's disease phenotype. Normalizing myofilament Ca2+ sensitivity may be a promising new treatment approach for a variety of diseases.
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Affiliation(s)
| | - Yeojung Koh
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Rebecca S Weller
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Rajdeep S Turna
- Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Ferhaan Ahmad
- Department of Internal Medicine University of Iowa, Iowa City, IA, USA
| | - Sabine Huke
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN, USA; Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Björn C Knollmann
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN, USA
| | | | - Hyun Seok Hwang
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA.
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26
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Dvornikov AV, de Tombe PP, Xu X. Phenotyping cardiomyopathy in adult zebrafish. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 138:116-125. [PMID: 29884423 PMCID: PMC6269218 DOI: 10.1016/j.pbiomolbio.2018.05.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 04/26/2018] [Accepted: 05/29/2018] [Indexed: 12/21/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is usually manifested by increased myofilament Ca2+ sensitivity, excessive contractility, and impaired relaxation. In contrast, dilated cardiomyopathy (DCM) originates from insufficient sarcomere contractility and reduced cardiac pump function, subsequently resulting in heart failure. The zebrafish has emerged as a new model of human cardiomyopathy with high-throughput screening, which will facilitate the discovery of novel genetic factors and the development of new therapies. Given the small hearts of zebrafish, better phenotyping tools are needed to discern different types of cardiomyopathy, such as HCM and DCM. This article reviews the existing models of cardiomyopathy, available morphologic and functional methods, and current understanding of the different types of cardiomyopathy in adult zebrafish.
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Affiliation(s)
- Alexey V Dvornikov
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
| | - Pieter P de Tombe
- University of Illinois at Chicago, Department of Physiology and Biophysics, Chicago, IL, USA; Magdi Yacoub Institute, Cardiac Biophysics Division, Harefield, UK; Imperial College, Heart and Lung Institute, London, UK; Freiburg University, Institute for Experimental Cardiovascular Medicine, Germany
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
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27
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Goldberg-Smith P. David M. Ryba. Circ Res 2018; 123:318-319. [DOI: 10.1161/circresaha.118.313597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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28
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Alves ML, Warren CM, Simon JN, Gaffin RD, Montminy EM, Wieczorek DF, Solaro RJ, Wolska BM. Early sensitization of myofilaments to Ca2+ prevents genetically linked dilated cardiomyopathy in mice. Cardiovasc Res 2018; 113:915-925. [PMID: 28379313 DOI: 10.1093/cvr/cvx068] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 03/31/2017] [Indexed: 12/14/2022] Open
Abstract
Background Dilated cardiomoypathies (DCM) are a heterogeneous group of inherited and acquired diseases characterized by decreased contractility and enlargement of cardiac chambers and a major cause of morbidity and mortality. Mice with Glu54Lys mutation in α-tropomyosin (Tm54) demonstrate typical DCM phenotype with reduced myofilament Ca2+ sensitivity. We tested the hypothesis that early sensitization of the myofilaments to Ca2+ in DCM can prevent the DCM phenotype. Methods and results To sensitize Tm54 myofilaments, we used a genetic approach and crossbred Tm54 mice with mice expressing slow skeletal troponin I (ssTnI) that sensitizes myofilaments to Ca2+. Four groups of mice were used: non-transgenic (NTG), Tm54, ssTnI and Tm54/ssTnI (DTG). Systolic function was significantly reduced in the Tm54 mice compared to NTG, but restored in DTG mice. Tm54 mice also showed increased diastolic LV dimensions and HW/BW ratios, when compared to NTG, which were improved in the DTG group. β-myosin heavy chain expression was increased in the Tm54 animals compared to NTG and was partially restored in DTG group. Analysis by 2D-DIGE indicated a significant decrease in two phosphorylated spots of cardiac troponin I (cTnI) in the DTG animals compared to NTG and Tm54. Analysis by 2D-DIGE also indicated no significant changes in troponin T, regulatory light chain, myosin binding protein C and tropomyosin phosphorylation. Conclusion Our data indicate that decreased myofilament Ca2+ sensitivity is an essential element in the pathophysiology of thin filament linked DCM. Sensitization of myofilaments to Ca2+ in the early stage of DCM may be a useful therapeutic strategy in thin filament linked DCM.
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Affiliation(s)
- Marco L Alves
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA.,Center for Research in Echocardiography and Cardiology, Heart Institute, University of Sao Paulo, Avenida Dr. Eneas de Carvalho Aguiar 44, 05403-900, Sao Paulo, Brazil
| | - Chad M Warren
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Jillian N Simon
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Robert D Gaffin
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Eric M Montminy
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - David F Wieczorek
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
| | - R John Solaro
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Beata M Wolska
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA.,Department of Medicine, Division of Cardiology, University of Illinois, 840 S Wood St. (M/C 715), Chicago, IL 60612, USA
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29
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Hayamizu K, Morimoto S, Nonaka M, Hoka S, Sasaguri T. Cardiotonic actions of quercetin and its metabolite tamarixetin through a digitalis-like enhancement of Ca2+ transients. Arch Biochem Biophys 2018; 637:40-47. [DOI: 10.1016/j.abb.2017.11.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 11/11/2017] [Accepted: 11/15/2017] [Indexed: 12/23/2022]
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30
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Kampourakis T, Zhang X, Sun YB, Irving M. Omecamtiv mercabil and blebbistatin modulate cardiac contractility by perturbing the regulatory state of the myosin filament. J Physiol 2017; 596:31-46. [PMID: 29052230 PMCID: PMC5746517 DOI: 10.1113/jp275050] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/06/2017] [Indexed: 01/10/2023] Open
Abstract
Key points Omecamtiv mecarbil and blebbistatin perturb the regulatory state of the thick filament in heart muscle. Omecamtiv mecarbil increases contractility at low levels of activation by stabilizing the ON state of the thick filament. Omecamtiv mecarbil decreases contractility at high levels of activation by disrupting the acto‐myosin ATPase cycle. Blebbistatin reduces contractility by stabilizing the thick filament OFF state and inhibiting acto‐myosin ATPase. Thick filament regulation is a promising target for novel therapeutics in heart disease.
Abstract Contraction of heart muscle is triggered by a transient rise in intracellular free calcium concentration linked to a change in the structure of the actin‐containing thin filaments that allows the head or motor domains of myosin from the thick filaments to bind to them and induce filament sliding. It is becoming increasingly clear that cardiac contractility is also regulated through structural changes in the thick filaments, although the molecular mechanisms underlying thick filament regulation are still relatively poorly understood. Here we investigated those mechanisms using small molecules – omecamtiv mecarbil (OM) and blebbistatin (BS) – that bind specifically to myosin and respectively activate or inhibit contractility in demembranated cardiac muscle cells. We measured isometric force and ATP utilization at different calcium and small‐molecule concentrations in parallel with in situ structural changes determined using fluorescent probes on the myosin regulatory light chain in the thick filaments and on troponin C in the thin filaments. The results show that BS inhibits contractility and actin‐myosin ATPase by stabilizing the OFF state of the thick filament in which myosin head domains are more parallel to the filament axis. In contrast, OM stabilizes the ON state of the thick filament, but inhibits contractility at high intracellular calcium concentration by disrupting the actin‐myosin ATPase pathway. The effects of BS and OM on the calcium sensitivity of isometric force and filament structural changes suggest that the co‐operativity of calcium activation in physiological conditions is due to positive coupling between the regulatory states of the thin and thick filaments. Omecamtiv mecarbil and blebbistatin perturb the regulatory state of the thick filament in heart muscle. Omecamtiv mecarbil increases contractility at low levels of activation by stabilizing the ON state of the thick filament. Omecamtiv mecarbil decreases contractility at high levels of activation by disrupting the acto‐myosin ATPase cycle. Blebbistatin reduces contractility by stabilizing the thick filament OFF state and inhibiting acto‐myosin ATPase. Thick filament regulation is a promising target for novel therapeutics in heart disease.
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Affiliation(s)
- Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Xuemeng Zhang
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
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31
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Horváth B, Szentandrássy N, Veress R, Almássy J, Magyar J, Bányász T, Tóth A, Papp Z, Nánási PP. Frequency-dependent effects of omecamtiv mecarbil on cell shortening of isolated canine ventricular cardiomyocytes. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:1239-1246. [PMID: 28940010 DOI: 10.1007/s00210-017-1422-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/31/2017] [Indexed: 01/10/2023]
Abstract
Omecamtiv mecarbil (OM) is a myosin activator agent developed for the treatment of heart failure. OM was reported to increase left ventricular ejection fraction and systolic ejection time, but little is known about the effect of heart rate on the action of OM. The present study, therefore, was designed to investigate the effects of OM on unloaded cell shortening and intracellular Ca2+ ([Ca2+]i) transients as a function of the pacing frequency. Isolated cardiomyocytes were stimulated at various frequencies under steady-state conditions. Cell length was monitored by an optical edge detector and changes in [Ca2+]i were followed using the Ca2+-sensitive dye Fura-2. At the pacing frequency of 1 Hz, OM (1-10 μM) significantly decreased both diastolic and systolic cell length, however, fractional shortening was augmented only by 1 μM OM. Time to peak tension and time of 90% relaxation were progressively increased by OM. At the frequency of 2 Hz, diastolic cell length was reduced by 10 μM OM to a larger extent than systolic cell length, resulting in a significantly decreased fractional shortening under these conditions. OM had no effect on the parameters of the [Ca2+]i transient at any pacing frequency. The results suggest that supratherapeutic concentrations of OM may decrease rather than increase the force of cardiac contraction especially in tachycardic patients.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.,Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
| | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Roland Veress
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.,Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Department of Cardiology, Research Center for Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltán Papp
- Division of Clinical Physiology, Department of Cardiology, Research Center for Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary. .,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary.
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Gollapudi SK, Reda SM, Chandra M. Omecamtiv Mecarbil Abolishes Length-Mediated Increase in Guinea Pig Cardiac Myofiber Ca 2+ Sensitivity. Biophys J 2017; 113:880-888. [PMID: 28834724 DOI: 10.1016/j.bpj.2017.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/19/2017] [Accepted: 07/05/2017] [Indexed: 01/14/2023] Open
Abstract
Omecamtiv mecarbil (OM) is a pharmacological agent that augments cardiac contractile function by enhancing myofilament Ca2+ sensitivity. Given that interventions that increase myofilament Ca2+ sensitivity have the potential to alter length-dependent activation (LDA) of cardiac myofilaments, we tested the influence of OM on this fundamental property of the heart. This is significant not only because LDA is prominent in cardiac muscle but also because it contributes to the Frank-Starling law, a mechanism by which the heart increases stroke volume in response to an increase in venous return. We measured steady-state and dynamic contractile indices in detergent-skinned guinea pig (Cavia porcellus) cardiac muscle fibers in the absence and presence of 0.3 and 3.0 μM OM at two different sarcomere lengths (SLs), short SL (1.9 μm) and long SL (2.3 μm). Myofilament Ca2+ sensitivity, as measured by pCa50 (-log of [Ca2+]free concentration required for half-maximal activation), increased significantly at both short and long SLs in OM-treated fibers when compared to untreated fibers; however, the magnitude of increase in pCa50 was twofold greater at short SL than at long SL. A consequence of this greater increase in pCa50 at short SL was that pCa50 did not increase any further at long SL, suggesting that OM abolished the SL dependency of pCa50. Furthermore, the SL dependency of rate constants of cross-bridge distortion dynamics (c) and force redevelopment (ktr) was abolished in 0.3-μM-OM-treated fibers. The negative impact of OM on the SL dependency of pCa50, c, and ktr was also observed in 3.0-μM-OM-treated fibers, indicating that cooperative mechanisms linked to LDA were altered by the OM-mediated effects on cardiac myofilaments.
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Affiliation(s)
- Sampath K Gollapudi
- Department of Integrative Physiology and Neuroscience (IPN), Washington State University, Pullman, Washington
| | - Sherif M Reda
- Department of Integrative Physiology and Neuroscience (IPN), Washington State University, Pullman, Washington
| | - Murali Chandra
- Department of Integrative Physiology and Neuroscience (IPN), Washington State University, Pullman, Washington.
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Nánási P, Gaburjakova M, Gaburjakova J, Almássy J. Omecamtiv mecarbil activates ryanodine receptors from canine cardiac but not skeletal muscle. Eur J Pharmacol 2017; 809:73-79. [PMID: 28506910 DOI: 10.1016/j.ejphar.2017.05.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 05/01/2017] [Accepted: 05/12/2017] [Indexed: 01/10/2023]
Abstract
Due to the limited results achieved in the clinical treatment of heart failure, a new inotropic strategy of myosin motor activation has been developed. The lead molecule of myosin activator agents is omecamtiv mecarbil, which binds directly to the heavy chain of the cardiac β-myosin and enhances cardiac contractility by lengthening the lifetime of the acto-myosin complex and increasing the number of the active force-generating cross-bridges. In the absence of relevant data, the effect of omecamtiv mecarbil on canine cardiac ryanodine receptors (RyR 2) has been investigated in the present study by measuring the electrical activity of single RyR 2 channels incorporated into planar lipid bilayer. When applying 100nM Ca2+ concentration on the cis side ([Ca2+]cis) omecamtiv mecarbil (1-10µM) significantly increased the open probability and opening frequency of RyR 2, while the mean closed time was reduced. Mean open time was increased moderately by 10µM omecamtiv mecarbil. When [Ca2+]cis was elevated to 322 and 735nM, the effect of omecamtiv mecarbil on open probability was evident only at higher (3-10µM) concentrations. All effects of omecamtiv mecarbil were fully reversible upon washout. Omecamtiv mecarbil (up to 10µM) had no effect on the open probability of RyR 1, isolated from either canine or rabbit skeletal muscles. It is concluded that the direct stimulatory action of omecamtiv mecarbil on RyR 2 has to be taken into account when discussing the mechanism of action or the potential side effects of the compound.
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Affiliation(s)
- Péter Nánási
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Marta Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Jana Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - János Almássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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Swenson AM, Tang W, Blair CA, Fetrow CM, Unrath WC, Previs MJ, Campbell KS, Yengo CM. Omecamtiv Mecarbil Enhances the Duty Ratio of Human β-Cardiac Myosin Resulting in Increased Calcium Sensitivity and Slowed Force Development in Cardiac Muscle. J Biol Chem 2017; 292:3768-3778. [PMID: 28082673 DOI: 10.1074/jbc.m116.748780] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 01/05/2017] [Indexed: 01/10/2023] Open
Abstract
The small molecule drug omecamtiv mecarbil (OM) specifically targets cardiac muscle myosin and is known to enhance cardiac muscle performance, yet its impact on human cardiac myosin motor function is unclear. We expressed and purified human β-cardiac myosin subfragment 1 (M2β-S1) containing a C-terminal Avi tag. We demonstrate that the maximum actin-activated ATPase activity of M2β-S1 is slowed more than 4-fold in the presence of OM, whereas the actin concentration required for half-maximal ATPase was reduced dramatically (30-fold). We find OM does not change the overall actin affinity. Transient kinetic experiments suggest that there are two kinetic pathways in the presence of OM. The dominant pathway results in a slow transition between actomyosin·ADP states and increases the time myosin is strongly bound to actin. However, OM also traps a population of myosin heads in a weak actin affinity state with slow product release. We demonstrate that OM can reduce the actin sliding velocity more than 100-fold in the in vitro motility assay. The ionic strength dependence of in vitro motility suggests the inhibition may be at least partially due to drag forces from weakly attached myosin heads. OM causes an increase in duty ratio examined in the motility assay. Experiments with permeabilized human myocardium demonstrate that OM increases calcium sensitivity and slows force development (ktr) in a concentration-dependent manner, whereas the maximally activated force is unchanged. We propose that OM increases the myosin duty ratio, which results in enhanced calcium sensitivity but slower force development in human myocardium.
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Affiliation(s)
- Anja M Swenson
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Wanjian Tang
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Cheavar A Blair
- the Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, and
| | - Christopher M Fetrow
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - William C Unrath
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Michael J Previs
- the Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, Vermont 05405
| | - Kenneth S Campbell
- the Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, and
| | - Christopher M Yengo
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033,
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Tang W, Blair CA, Walton SD, Málnási-Csizmadia A, Campbell KS, Yengo CM. Modulating Beta-Cardiac Myosin Function at the Molecular and Tissue Levels. Front Physiol 2017; 7:659. [PMID: 28119616 PMCID: PMC5220080 DOI: 10.3389/fphys.2016.00659] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 12/15/2016] [Indexed: 01/10/2023] Open
Abstract
Inherited cardiomyopathies are a common form of heart disease that are caused by mutations in sarcomeric proteins with beta cardiac myosin (MYH7) being one of the most frequently affected genes. Since the discovery of the first cardiomyopathy associated mutation in beta-cardiac myosin, a major goal has been to correlate the in vitro myosin motor properties with the contractile performance of cardiac muscle. There has been substantial progress in developing assays to measure the force and velocity properties of purified cardiac muscle myosin but it is still challenging to correlate results from molecular and tissue-level experiments. Mutations that cause hypertrophic cardiomyopathy are more common than mutations that lead to dilated cardiomyopathy and are also often associated with increased isometric force and hyper-contractility. Therefore, the development of drugs designed to decrease isometric force by reducing the duty ratio (the proportion of time myosin spends bound to actin during its ATPase cycle) has been proposed for the treatment of hypertrophic cardiomyopathy. Para-Nitroblebbistatin is a small molecule drug proposed to decrease the duty ratio of class II myosins. We examined the impact of this drug on human beta cardiac myosin using purified myosin motor assays and studies of permeabilized muscle fiber mechanics. We find that with purified human beta-cardiac myosin para-Nitroblebbistatin slows actin-activated ATPase and in vitro motility without altering the ADP release rate constant. In permeabilized human myocardium, para-Nitroblebbistatin reduces isometric force, power, and calcium sensitivity while not changing shortening velocity or the rate of force development (ktr). Therefore, designing a drug that reduces the myosin duty ratio by inhibiting strong attachment to actin while not changing detachment can cause a reduction in force without changing shortening velocity or relaxation.
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Affiliation(s)
- Wanjian Tang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | - Cheavar A Blair
- Department of Physiology, University of Kentucky Lexington, KY, USA
| | - Shane D Walton
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | | | - Kenneth S Campbell
- Department of Physiology, University of KentuckyLexington, KY, USA; Division of Cardiovascular Medicine, University of KentuckyLexington, KY, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
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36
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Solaro RJ. Why we need to understand the mechanics of developing cardiac sarcomeres in humans. J Physiol 2016; 594:255. [PMID: 26767884 DOI: 10.1113/jp271706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 10/24/2015] [Indexed: 01/24/2023] Open
Affiliation(s)
- R John Solaro
- Department of Physiology and Biophysics and Centre for Cardiovascular Research, University of Illinois at Chicago, College of Medicine, Chicago, IL, 60612, USA
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37
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Broughton KM, Li J, Sarmah E, Warren CM, Lin YH, Henze MP, Sanchez-Freire V, Solaro RJ, Russell B. A myosin activator improves actin assembly and sarcomere function of human-induced pluripotent stem cell-derived cardiomyocytes with a troponin T point mutation. Am J Physiol Heart Circ Physiol 2016; 311:H107-17. [PMID: 27199119 DOI: 10.1152/ajpheart.00162.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/02/2016] [Indexed: 11/22/2022]
Abstract
We have investigated cardiac myocytes derived from human-induced pluripotent stem cells (iPSC-CMs) from two normal control and two family members expressing a mutant cardiac troponin T (cTnT-R173W) linked to dilated cardiomyopathy (DCM). cTnT is a regulatory protein of the sarcomeric thin filament. The loss of this basic charge, which is strategically located to control tension, has consequences leading to progressive DCM. iPSC-CMs serve as a valuable platform for understanding clinically relevant mutations in sarcomeric proteins; however, there are important questions to be addressed with regard to myocyte adaptation that we model here by plating iPSC-CMs on softer substrates (100 kPa) to create a more physiologic environment during recovery and maturation of iPSC-CMs after thawing from cryopreservation. During the first week of culture of the iPSC-CMs, we have determined structural and functional characteristics as well as actin assembly dynamics. Shortening, actin content, and actin assembly dynamics were depressed in CMs from the severely affected mutant at 1 wk of culture, but by 2 wk differences were less apparent. Sarcomeric troponin and myosin isoform composition were fetal/neonatal. Furthermore, the troponin complex, reconstituted with wild-type cTnT or recombinant cTnT-R173W, depressed the entry of cross-bridges into the force-generating state, which can be reversed by the myosin activator omecamtiv mecarbil. Therapeutic doses of this drug increased both contractility and the content of F-actin in the mutant iPSC-CMs. Collectively, our data suggest the use of a myosin activation reagent to restore function within patient-specific iPSC-CMs may aid in understanding and treating this familial DCM.
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Affiliation(s)
- K M Broughton
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - J Li
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - E Sarmah
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - C M Warren
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - Y-H Lin
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - M P Henze
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - V Sanchez-Freire
- Department of Medicine, Division of Cardiology, Stanford University School of Medicine, Stanford, California
| | - R J Solaro
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - B Russell
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
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38
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Liu LC, Dorhout B, van der Meer P, Teerlink JR, Voors AA. Omecamtiv mecarbil: a new cardiac myosin activator for the treatment of heart failure. Expert Opin Investig Drugs 2015; 25:117-27. [PMID: 26587768 DOI: 10.1517/13543784.2016.1123248] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
INTRODUCTION Current available inotropic agents increase cardiac contractility, but are associated with myocardial ischemia, arrhythmias, and mortality. A novel selective cardiac myosin activator, omecamtiv mecarbil (CK-1827452/ AMG-423) is a small molecule that activates the sarcomere proteins directly, resulting in prolonged systolic ejection time and increased cardiac contractility. AREAS COVERED This paper discusses the chemistry, pharmacokinetics, clinical efficacy and safety of omecamtiv mecarbil. Omecamtiv mecarbil represents a novel therapeutic approach to directly improve cardiac function and is therefore proposed as a potential new treatment of patients with systolic heart failure. The authors review results of previous studies investigating the effect of omecamtiv mecarbil in heart failure animal models, healthy volunteers, and patients with acute and chronic systolic heart failure. EXPERT OPINION Results of phase I and phase II studies demonstrate that omecamtiv mecarbil is safe and well tolerated both as an intravenous and oral formulation. In healthy volunteers and chronic systolic heart failure patients, administration of omecamtiv mecarbil resulted in a concentration-dependent increase of left ventricular ejection time, ejection fraction, fractional shortening, and stroke volume. The first results of a double-blind, randomized, placebo-controlled phase IIb dose-finding study with the oral formulation of omecamtiv mecarbil demonstrated beneficial effects on cardiac function and N-terminal pro-brain natriuretic peptide levels. This study will provide essential dosing information for the requisite phase III trials which will investigate whether the beneficial effects of omecamtiv mecarbil translate into improved clinical outcomes.
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Affiliation(s)
- Licette Cy Liu
- a Department of Cardiology , University Medical Center Groningen, University of Groningen , Groningen , 9713 GZ , the Netherlands
| | - Bernard Dorhout
- a Department of Cardiology , University Medical Center Groningen, University of Groningen , Groningen , 9713 GZ , the Netherlands
| | - Peter van der Meer
- a Department of Cardiology , University Medical Center Groningen, University of Groningen , Groningen , 9713 GZ , the Netherlands
| | - John R Teerlink
- b Section of Cardiology, San Francisco Veterans Affairs Medical Center and School of Medicine , University of California San Francisco , San Francisco , CA , USA
| | - Adriaan A Voors
- a Department of Cardiology , University Medical Center Groningen, University of Groningen , Groningen , 9713 GZ , the Netherlands
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