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Euler L, Deinert K, Wagener F, Walpurgis K, Thevis M. Identification of human metabolites of fast skeletal troponin activators Tirasemtiv and Reldesemtiv for doping control purposes. Drug Test Anal 2024. [PMID: 39138120 DOI: 10.1002/dta.3786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2024] [Revised: 07/17/2024] [Accepted: 07/24/2024] [Indexed: 08/15/2024]
Abstract
The fast skeletal troponin activators (FSTAs) Reldesemtiv and Tirasemtiv were developed for patients suffering from neuro-degenerative diseases of the motor nervous system, e.g. amyotrophic lateral sclerosis (ALS). The drug candidates can increase the sensitivity of troponin C to calcium by selectively activating the troponin complex resulting in increased skeletal muscle contraction. Although the development of the drug candidates is currently discontinued because of missed end points in phase III clinical studies with patients with ALS, phase I clinical trials showed an increase in muscle contraction force in healthy humans. This effect could be abused by athletes to enhance performance in sports. As the substances are listed on the 2024 edition of the World Anti-Doping Agency's Prohibited List, the aim of this study was to identify and characterize metabolites of Reldesemtiv and Tirasemtiv to ensure their reliable identification in doping control analyses. The biotransformation of the drug candidates was studied in vitro using pooled human liver microsomes and 3D cultivated human hepatic cells of the cell line HepaRG, yielding a total of 11 metabolites of Reldesemtiv and eight of Tirasemtiv. In addition, a human elimination study was conducted to investigate the metabolism and elimination profile of Tirasemtiv and Reldesemtiv in vivo, suggesting the N-glucuronide of Tirasemtiv and hydroxylated 3-fluoro-2-(3-fluoro-1-methylcyclobutyl)pyridine as well as its glucuronide as suitable target analytes for routine doping controls. Applying a validating HPLC-MS/MS method, optimized to detect Reldesemtiv and Tirasemtiv in human urine, microdosing (50 μg) of each substance was traceable for 24-72 h.
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Affiliation(s)
- Luisa Euler
- Center for Preventive Doping Research Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Kim Deinert
- Center for Preventive Doping Research Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
- Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Felicitas Wagener
- Center for Preventive Doping Research Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Katja Walpurgis
- Center for Preventive Doping Research Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Mario Thevis
- Center for Preventive Doping Research Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
- European Monitoring Center for Emerging Doping Agents, Cologne, Germany
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2
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Wei Y, Zhong S, Yang H, Wang X, Lv B, Bian Y, Pei Y, Xu C, Zhao Q, Wu Y, Luo D, Wang F, Sun H, Chen Y. Current therapy in amyotrophic lateral sclerosis (ALS): A review on past and future therapeutic strategies. Eur J Med Chem 2024; 272:116496. [PMID: 38759454 DOI: 10.1016/j.ejmech.2024.116496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 05/11/2024] [Accepted: 05/11/2024] [Indexed: 05/19/2024]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects the first and second motoneurons (MNs), associated with muscle weakness, paralysis and finally death. The exact etiology of the disease still remains unclear. Currently, efforts to develop novel ALS treatments which target specific pathomechanisms are being studied. The mechanisms of ALS pathogenesis involve multiple factors, such as protein aggregation, glutamate excitotoxicity, oxidative stress, mitochondrial dysfunction, apoptosis, inflammation etc. Unfortunately, to date, there are only two FDA-approved drugs for ALS, riluzole and edavarone, without curative treatment for ALS. Herein, we give an overview of the many pathways and review the recent discovery and preclinical characterization of neuroprotective compounds. Meanwhile, drug combination and other therapeutic approaches are also reviewed. In the last part, we analyze the reasons of clinical failure and propose perspective on the treatment of ALS in the future.
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Affiliation(s)
- Yuqing Wei
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Sheng Zhong
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Huajing Yang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Xueqing Wang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Bingbing Lv
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Yaoyao Bian
- Jiangsu Provincial Engineering Center of TCM External Medication Researching and Industrializing, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Yuqiong Pei
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Chunlei Xu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Qun Zhao
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Yulan Wu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Daying Luo
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Fan Wang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Haopeng Sun
- School of Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
| | - Yao Chen
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China.
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Herskind J, Ørtenblad N, Cheng AJ, Pedersen P, Overgaard K. Piperine enhances contractile force in slow- and fast-twitch muscle. J Physiol 2024; 602:2807-2822. [PMID: 38762879 DOI: 10.1113/jp285995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 04/30/2024] [Indexed: 05/21/2024] Open
Abstract
Piperine has been shown to bind to myosin and shift the distribution of conformational states of myosin molecules from the super-relaxed state to the disordered relaxed state. However, little is known about the implications for muscle force production and potential underlying mechanisms. Muscle contractility experiments were performed using isolated muscles and single fibres from rats and mice. The dose-response effect of piperine on muscle force was assessed at several stimulation frequencies. The potentiation of muscle force was also tested in muscles fatigued by eccentric contractions. Potential mechanisms of force potentiation were assessed by measuring Ca2+ levels during stimulation in enzymatically dissociated muscle fibres, while myofibrillar Ca2+ sensitivity was assessed in chemically skinned muscle fibres. Piperine caused a dose-dependent increase in low-frequency force with no effect on high-frequency force in both slow- and fast-twitch muscle, with similar relative increases in twitch force, rate of force development and relaxation rate. The potentiating effect of piperine on low-frequency force was reversible, and piperine partially recovered low-frequency force in fatigued muscle. Piperine had no effect on myoplasmic free [Ca2+] levels in mouse muscle fibres, whereas piperine substantially augmented the force response to submaximal levels of [Ca2+] in rat MyHCII fibres and MyHCI fibres along with a minor increase in maximum Ca2+-activated force. Piperine enhances low-frequency force production in both fast- and slow-twitch muscle. The effects are reversible and can counteract muscle fatigue. The primary underlying mechanism appears to be an increase in Ca2+ sensitivity. KEY POINTS: Piperine is a plant alkaloid derived from black pepper. It is known to bind to skeletal muscle myosin and enhance resting ATP turnover but its effects on contractility are not well known. We showed for the first time a piperine-induced force potentiation that was pronounced during low-frequency electrical stimulation of isolated muscles. The effect of piperine was observed in both slow and fast muscle types, was reversible, and could counteract the force decrements observed after fatiguing muscle contractions. Piperine treatment caused an increase in myofibrillar Ca2+ sensitivity in chemically skinned muscle fibres, while we observed no effect on intracellular Ca2+ concentrations during electrical stimulation in enzymatically dissociated muscle fibres.
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Affiliation(s)
- Jon Herskind
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Arthur J Cheng
- Muscle Health Research Centre, School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, Ontario, Canada
| | - Peter Pedersen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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Claassen WJ, Baelde RJ, Galli RA, de Winter JM, Ottenheijm CAC. Small molecule drugs to improve sarcomere function in those with acquired and inherited myopathies. Am J Physiol Cell Physiol 2023; 325:C60-C68. [PMID: 37212548 PMCID: PMC10281779 DOI: 10.1152/ajpcell.00047.2023] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/23/2023]
Abstract
Muscle weakness is a hallmark of inherited or acquired myopathies. It is a major cause of functional impairment and can advance to life-threatening respiratory insufficiency. During the past decade, several small-molecule drugs that improve the contractility of skeletal muscle fibers have been developed. In this review, we provide an overview of the available literature and the mechanisms of action of small-molecule drugs that modulate the contractility of sarcomeres, the smallest contractile units in striated muscle, by acting on myosin and troponin. We also discuss their use in the treatment of skeletal myopathies. The first of three classes of drugs discussed here increase contractility by decreasing the dissociation rate of calcium from troponin and thereby sensitizing the muscle to calcium. The second two classes of drugs directly act on myosin and stimulate or inhibit the kinetics of myosin-actin interactions, which may be useful in patients with muscle weakness or stiffness.NEW & NOTEWORTHY During the past decade, several small molecule drugs that improve the contractility of skeletal muscle fibers have been developed. In this review, we provide an overview of the available literature and the mechanisms of action of small molecule drugs that modulate the contractility of sarcomeres, the smallest contractile units in striated muscle, by acting on myosin and troponin.
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Affiliation(s)
- Wout J Claassen
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Rianne J Baelde
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Ricardo A Galli
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Josine M de Winter
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Coen A C Ottenheijm
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
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Leijding C, Viken I, Bruton JD, Andersson DC, Cheng AJ, Westerblad H. Increased tetanic calcium in early fatigue of mammalian muscle fibers is accompanied by accelerated force development despite a decreased force. FASEB J 2023; 37:e22978. [PMID: 37191967 DOI: 10.1096/fj.202300401r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/18/2023] [Accepted: 05/05/2023] [Indexed: 05/17/2023]
Abstract
During the initial phase of fatigue induced by repeated contractions in fast-twitch muscle fibers, tetanic force decreases despite increasing tetanic free cytosolic [Ca2+ ] ([Ca2+ ]cyt ). Here, we hypothesized that the increase in tetanic [Ca2+ ]cyt nevertheless has positive effects on force in early fatigue. Experiments on enzymatically isolated mouse flexor digitorum brevis (FDB) fibers showed that an increase in tetanic [Ca2+ ]cyt during ten 350 ms contractions required trains of electrical pulses to be elicited at short intervals (≤2 s) and at high frequencies (≥70 Hz). Mechanically dissected mouse FDB fibers showed greater decrease in tetanic force when the stimulation frequency during contractions was gradually reduced to prevent the increase in tetanic [Ca2+ ]cyt . Novel analyses of data from previous studies revealed an increased rate of force development in the tenth fatiguing contraction in mouse FDB fibers, as well as in rat FDB and human intercostal fibers. Mouse FDB fibers deficient in creatine kinase showed no increase in tetanic [Ca2+ ]cyt and slowed force development in the tenth contraction; after injection of creatine kinase to enable phosphocreatine breakdown, these fibers showed an increase in tetanic [Ca2+ ]cyt and accelerated force development. Mouse FDB fibers exposed to ten short contractions (43 ms) produced at short intervals (142 ms) showed increased tetanic [Ca2+ ]cyt accompanied by a marked (~16%) increase in the developed force. In conclusion, the increase in tetanic [Ca2+ ]cyt in early fatigue is accompanied by accelerated force development, which under some circumstances can counteract the decline in physical performance caused by the concomitant decrease in maximum force.
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Affiliation(s)
- Cecilia Leijding
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Ida Viken
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Joseph D Bruton
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Daniel C Andersson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- Heart, Vascular and Neurology Theme, Cardiology Unit, Karolinska University Hospital, Stockholm, Sweden
| | - Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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6
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Kelsen A, Kent RS, Snyder AK, Wehri E, Bishop SJ, Stadler RV, Powell C, Martorelli di Genova B, Rompikuntal PK, Boulanger MJ, Warshaw DM, Westwood NJ, Schaletzky J, Ward GE. MyosinA is a druggable target in the widespread protozoan parasite Toxoplasma gondii. PLoS Biol 2023; 21:e3002110. [PMID: 37155705 PMCID: PMC10185354 DOI: 10.1371/journal.pbio.3002110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/15/2023] [Accepted: 04/05/2023] [Indexed: 05/10/2023] Open
Abstract
Toxoplasma gondii is a widespread apicomplexan parasite that can cause severe disease in its human hosts. The ability of T. gondii and other apicomplexan parasites to invade into, egress from, and move between cells of the hosts they infect is critical to parasite virulence and disease progression. An unusual and highly conserved parasite myosin motor (TgMyoA) plays a central role in T. gondii motility. The goal of this work was to determine whether the parasite's motility and lytic cycle can be disrupted through pharmacological inhibition of TgMyoA, as an approach to altering disease progression in vivo. To this end, we first sought to identify inhibitors of TgMyoA by screening a collection of 50,000 structurally diverse small molecules for inhibitors of the recombinant motor's actin-activated ATPase activity. The top hit to emerge from the screen, KNX-002, inhibited TgMyoA with little to no effect on any of the vertebrate myosins tested. KNX-002 was also active against parasites, inhibiting parasite motility and growth in culture in a dose-dependent manner. We used chemical mutagenesis, selection in KNX-002, and targeted sequencing to identify a mutation in TgMyoA (T130A) that renders the recombinant motor less sensitive to compound. Compared to wild-type parasites, parasites expressing the T130A mutation showed reduced sensitivity to KNX-002 in motility and growth assays, confirming TgMyoA as a biologically relevant target of KNX-002. Finally, we present evidence that KNX-002 can slow disease progression in mice infected with wild-type parasites, but not parasites expressing the resistance-conferring TgMyoA T130A mutation. Taken together, these data demonstrate the specificity of KNX-002 for TgMyoA, both in vitro and in vivo, and validate TgMyoA as a druggable target in infections with T. gondii. Since TgMyoA is essential for virulence, conserved in apicomplexan parasites, and distinctly different from the myosins found in humans, pharmacological inhibition of MyoA offers a promising new approach to treating the devastating diseases caused by T. gondii and other apicomplexan parasites.
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Affiliation(s)
- Anne Kelsen
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Robyn S. Kent
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Anne K. Snyder
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Eddie Wehri
- Center for Emerging and Neglected Diseases, University of California Berkeley, California, United States of America
| | - Stephen J. Bishop
- School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, St Andrews, Fife, Scotland, United Kingdom
| | - Rachel V. Stadler
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Cameron Powell
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Bruno Martorelli di Genova
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Pramod K. Rompikuntal
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Martin J. Boulanger
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Nicholas J. Westwood
- School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, St Andrews, Fife, Scotland, United Kingdom
| | - Julia Schaletzky
- Center for Emerging and Neglected Diseases, University of California Berkeley, California, United States of America
| | - Gary E. Ward
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
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7
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Karpicheva OE, Avrova SV, Bogdanov AL, Sirenko VV, Redwood CS, Borovikov YS. Molecular Mechanisms of Deregulation of Muscle Contractility Caused by the R168H Mutation in TPM3 and Its Attenuation by Therapeutic Agents. Int J Mol Sci 2023; 24:ijms24065829. [PMID: 36982903 PMCID: PMC10051413 DOI: 10.3390/ijms24065829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 03/30/2023] Open
Abstract
The substitution for Arg168His (R168H) in γ-tropomyosin (TPM3 gene, Tpm3.12 isoform) is associated with congenital muscle fiber type disproportion (CFTD) and muscle weakness. It is still unclear what molecular mechanisms underlie the muscle dysfunction seen in CFTD. The aim of this work was to study the effect of the R168H mutation in Tpm3.12 on the critical conformational changes that myosin, actin, troponin, and tropomyosin undergo during the ATPase cycle. We used polarized fluorescence microscopy and ghost muscle fibers containing regulated thin filaments and myosin heads (myosin subfragment-1) modified with the 1,5-IAEDANS fluorescent probe. Analysis of the data obtained revealed that a sequential interdependent conformational-functional rearrangement of tropomyosin, actin and myosin heads takes place when modeling the ATPase cycle in the presence of wild-type tropomyosin. A multistep shift of the tropomyosin strands from the outer to the inner domain of actin occurs during the transition from weak to strong binding of myosin to actin. Each tropomyosin position determines the corresponding balance between switched-on and switched-off actin monomers and between the strongly and weakly bound myosin heads. At low Ca2+, the R168H mutation was shown to switch some extra actin monomers on and increase the persistence length of tropomyosin, demonstrating the freezing of the R168HTpm strands close to the open position and disruption of the regulatory function of troponin. Instead of reducing the formation of strong bonds between myosin heads and F-actin, troponin activated it. However, at high Ca2+, troponin decreased the amount of strongly bound myosin heads instead of promoting their formation. Abnormally high sensitivity of thin filaments to Ca2+, inhibition of muscle fiber relaxation due to the appearance of the myosin heads strongly associated with F-actin, and distinct activation of the contractile system at submaximal concentrations of Ca2+ can lead to muscle inefficiency and weakness. Modulators of troponin (tirasemtiv and epigallocatechin-3-gallate) and myosin (omecamtiv mecarbil and 2,3-butanedione monoxime) have been shown to more or less attenuate the negative effects of the tropomyosin R168H mutant. Tirasemtiv and epigallocatechin-3-gallate may be used to prevent muscle dysfunction.
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Affiliation(s)
- Olga E Karpicheva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Stanislava V Avrova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Andrey L Bogdanov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Vladimir V Sirenko
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Charles S Redwood
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Yurii S Borovikov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
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Fielding RA, LeBrasseur NK. Editorial: Outcomes for Regulatory Approval in Geriatrics: Embracing Loss of Mobility and Mobility Disability as Clinically Meaningful Therapeutic Indications. J Nutr Health Aging 2023; 27:496-497. [PMID: 37498095 DOI: 10.1007/s12603-023-1944-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 07/28/2023]
Affiliation(s)
- R A Fielding
- Roger A. Fielding, Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center, Tufts University, Boston, Massachusetts, USA,
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9
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Singh RR, Slater RE, Wang J, Wang C, Guo Q, Motani AS, Hartman JJ, Sadayappan S, Ason BL. Distinct Mechanisms for Increased Cardiac Contraction Through Selective Alteration of Either Myosin or Troponin Activity. JACC Basic Transl Sci 2022; 7:1021-1037. [DOI: 10.1016/j.jacbts.2022.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 10/14/2022]
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10
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Collibee SE, Bergnes G, Chuang C, Ashcraft L, Gardina J, Garard M, Jamison CR, Lu K, Lu PP, Muci A, Romero A, Valkevich E, Wang W, Warrington J, Yao B, Durham N, Hartman J, Marquez A, Hinken A, Schaletzky J, Xu D, Hwee DT, Morgans D, Malik FI, Morgan BP. Discovery of Reldesemtiv, a Fast Skeletal Muscle Troponin Activator for the Treatment of Impaired Muscle Function. J Med Chem 2021; 64:14930-14941. [PMID: 34636234 DOI: 10.1021/acs.jmedchem.1c01067] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The discovery of reldesemtiv, a second-generation fast skeletal muscle troponin activator (FSTA) that increases force production at submaximal stimulation frequencies, is reported. Property-based optimization of high throughput screening hit 1 led to compounds with improved free exposure and in vivo muscle activation potency compared to the first-generation FSTA, tirasemtiv. Reldesemtiv demonstrated increased muscle force generation in a phase 1 clinical trial and is currently being evaluated in clinical trials for the treatment of amyotrophic lateral sclerosis.
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Affiliation(s)
- Scott E Collibee
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Gustave Bergnes
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Chihyuan Chuang
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Luke Ashcraft
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Jeffrey Gardina
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Marc Garard
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Chris R Jamison
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Kevin Lu
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Pu-Ping Lu
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Alexander Muci
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Antonio Romero
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Ellen Valkevich
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Wenyue Wang
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Jeffrey Warrington
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Bing Yao
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Nickie Durham
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - James Hartman
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Anna Marquez
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Aaron Hinken
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Julia Schaletzky
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Donghong Xu
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Darren T Hwee
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - David Morgans
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Fady I Malik
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
| | - Bradley P Morgan
- Cytokinetics, Inc., 280 East Grand Avenue, South San Francisco, California 94080, United States
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11
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de Winter JM, Gineste C, Minardi E, Brocca L, Rossi M, Borsboom T, Beggs AH, Bernard M, Bendahan D, Hwee DT, Malik FI, Pellegrino MA, Bottinelli R, Gondin J, Ottenheijm CAC. Acute and chronic tirasemtiv treatment improves in vivo and in vitro muscle performance in actin-based nemaline myopathy mice. Hum Mol Genet 2021; 30:1305-1320. [PMID: 33909041 PMCID: PMC8255131 DOI: 10.1093/hmg/ddab112] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/09/2021] [Accepted: 04/07/2021] [Indexed: 12/13/2022] Open
Abstract
Nemaline myopathy, a disease of the actin-based thin filament, is one of the most frequent congenital myopathies. To date, no specific therapy is available to treat muscle weakness in nemaline myopathy. We tested the ability of tirasemtiv, a fast skeletal troponin activator that targets the thin filament, to augment muscle force-both in vivo and in vitro-in a nemaline myopathy mouse model with a mutation (H40Y) in Acta1. In Acta1H40Y mice, treatment with tirasemtiv increased the force response of muscles to submaximal stimulation frequencies. This resulted in a reduced energetic cost of force generation, which increases the force production during a fatigue protocol. The inotropic effects of tirasemtiv were present in locomotor muscles and, albeit to a lesser extent, in respiratory muscles, and they persisted during chronic treatment, an important finding as respiratory failure is the main cause of death in patients with congenital myopathy. Finally, translational studies on permeabilized muscle fibers isolated from a biopsy of a patient with the ACTA1H40Y mutation revealed that at physiological Ca2+ concentrations, tirasemtiv increased force generation to values that were close to those generated in muscle fibers of healthy subjects. These findings indicate the therapeutic potential of fast skeletal muscle troponin activators to improve muscle function in nemaline myopathy due to the ACTA1H40Y mutation, and future studies should assess their merit for other forms of nemaline myopathy and for other congenital myopathies.
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Affiliation(s)
- Josine M de Winter
- Department of Physiology, Amsterdam UMC (location VUmc), Amsterdam 1081 HV, The Netherlands
| | | | - Elisa Minardi
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Lorenza Brocca
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Maira Rossi
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Tamara Borsboom
- Department of Physiology, Amsterdam UMC (location VUmc), Amsterdam 1081 HV, The Netherlands
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Monique Bernard
- Aix-Marseille Univ, CNRS, CRMBM, UMR 7339, 13005 Marseille, France
| | - David Bendahan
- Aix-Marseille Univ, CNRS, CRMBM, UMR 7339, 13005 Marseille, France
| | - Darren T Hwee
- Research and Early Development, Cytokinetics Inc., South San Francisco, CA 94080, USA
| | - Fady I Malik
- Research and Early Development, Cytokinetics Inc., South San Francisco, CA 94080, USA
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
- Interdipartimental Centre for Biology and Sport Medicine, University of Pavia, Pavia 27100, Italy
| | - Roberto Bottinelli
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
- Istituti Clinici Maugeri (IRCCS), Scientific Institute of Pavia, Pavia 27100, Italy
| | - Julien Gondin
- Aix-Marseille Univ, CNRS, CRMBM, UMR 7339, 13005 Marseille, France
- Institut NeuroMyoGène, Université Claude Bernard Lyon 1, CNRS 5310, INSERM U1217, 69008, Lyon, France
| | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam UMC (location VUmc), Amsterdam 1081 HV, The Netherlands
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12
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Cheng AJ, Ström J, Hwee DT, Malik FI, Westerblad H. Fast skeletal muscle troponin activator CK-2066260 mitigates skeletal muscle weakness independently of the underlying cause. J Cachexia Sarcopenia Muscle 2020; 11:1747-1757. [PMID: 32954682 PMCID: PMC7749611 DOI: 10.1002/jcsm.12624] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 08/08/2020] [Accepted: 08/23/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Muscle weakness is a common symptom in numerous diseases and a regularly occurring problem associated with ageing. Prolonged low-frequency force depression (PLFFD) is a form of exercise-induced skeletal muscle weakness observed after exercise. Three different intramuscular mechanisms underlying PLFFD have been identified: decreased sarcoplasmic reticulum Ca2+ release, decreased myofibrillar Ca2+ sensitivity, and myofibrillar dysfunction. We here used these three forms of PLFFD as models to study the effectiveness of a fast skeletal muscle troponin activator, CK-2066260, to mitigate muscle weakness. METHODS Experiments were performed on intact single muscle fibres or fibre bundles from mouse flexor digitorum brevis, which were stimulated with electrical current pulses, while force and the free cytosolic [Ca2+ ] ([Ca2+ ]i ) were measured. PLFFD was induced by three different stimulation protocols: (i) repeated isometric contractions at low intensity (350 ms tetani given every 5 s for 100 contractions); (ii) repeated isometric contractions at high intensity (250 ms tetani given every 0.5 s for 300 contractions); and (iii) repeated eccentric contractions (350 ms tetani with 20% length increase given every 20 s for 10 contractions). The extent and cause of PLFFD were assessed by comparing the force-[Ca2+ ]i relationship at low (30 Hz) and high (120 Hz) stimulation frequencies before (control) and 30 min after induction of PLFFD, and after an additional 5 min of rest in the presence of CK-2066260 (10 μM). RESULTS Prolonged low-frequency force depression following low-intensity and high-intensity fatiguing contractions was predominantly due to decreased sarcoplasmic reticulum Ca2+ release and decreased myofibrillar Ca2+ sensitivity, respectively. CK-2066260 exposure resulted in marked increases in 30 Hz force from 52 ± 16% to 151 ± 13% and from 6 ± 4% to 98 ± 40% of controls with low-intensity and high-intensity contractions, respectively. Following repeated eccentric contractions, PLFFD was mainly due to myofibrillar dysfunction, and it was not fully reversed by CK-2066260 with 30 Hz force increasing from 48 ± 8% to 76 ± 6% of the control. CONCLUSIONS The fast skeletal muscle troponin activator CK-2066260 effectively mitigates muscle weakness, especially when it is caused by impaired activation of the myofibrillar contractile machinery due to either decreased sarcoplasmic reticulum Ca2+ release or reduced myofibrillar Ca2+ sensitivity.
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Affiliation(s)
- Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.,School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, Canada
| | - Jennifer Ström
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Darren T Hwee
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, USA
| | - Fady I Malik
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, USA
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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13
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Guhathakurta P, Phung LA, Prochniewicz E, Lichtenberger S, Wilson A, Thomas DD. Actin-binding compounds, previously discovered by FRET-based high-throughput screening, differentially affect skeletal and cardiac muscle. J Biol Chem 2020; 295:14100-14110. [PMID: 32788211 DOI: 10.1074/jbc.ra120.014445] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 08/06/2020] [Indexed: 01/21/2023] Open
Abstract
Actin's interactions with myosin and other actin-binding proteins are essential for cellular viability in numerous cell types, including muscle. In a previous high-throughput time-resolved FRET (TR-FRET) screen, we identified a class of compounds that bind to actin and affect actomyosin structure and function. For clinical utility, it is highly desirable to identify compounds that affect skeletal and cardiac muscle differently. Because actin is more highly conserved than myosin and most other muscle proteins, most such efforts have not targeted actin. Nevertheless, in the current study, we tested the specificity of the previously discovered actin-binding compounds for effects on skeletal and cardiac α-actins as well as on skeletal and cardiac myofibrils. We found that a majority of these compounds affected the transition of monomeric G-actin to filamentous F-actin, and that several of these effects were different for skeletal and cardiac actin isoforms. We also found that several of these compounds affected ATPase activity differently in skeletal and cardiac myofibrils. We conclude that these structural and biochemical assays can be used to identify actin-binding compounds that differentially affect skeletal and cardiac muscles. The results of this study set the stage for screening of large chemical libraries for discovery of novel compounds that act therapeutically and specifically on cardiac or skeletal muscle.
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Affiliation(s)
- Piyali Guhathakurta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Lien A Phung
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ewa Prochniewicz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sarah Lichtenberger
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Anna Wilson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA .,Photonic Pharma LLC, Minneapolis, Minnesota, USA
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14
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Liscic RM, Alberici A, Cairns NJ, Romano M, Buratti E. From basic research to the clinic: innovative therapies for ALS and FTD in the pipeline. Mol Neurodegener 2020; 15:31. [PMID: 32487123 PMCID: PMC7268618 DOI: 10.1186/s13024-020-00373-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 03/27/2020] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and Frontotemporal Degeneration (FTD) are neurodegenerative disorders, related by deterioration of motor and cognitive functions and short survival. Aside from cases with an inherited pathogenic mutation, the causes of the disorders are still largely unknown and no effective treatment currently exists. It has been shown that FTD may coexist with ALS and this overlap occurs at clinical, genetic, and molecular levels. In this work, we review the main pathological aspects of these complex diseases and discuss how the integration of the novel pathogenic molecular insights and the analysis of molecular interaction networks among all the genetic players represents a critical step to shed light on discovering novel therapeutic strategies and possibly tailoring personalized medicine approaches to specific ALS and FTD patients.
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Affiliation(s)
- Rajka Maria Liscic
- Department of Neurology, Johannes Kepler University, Linz, Austria
- School of Medicine, University of Osijek, Osijek, Croatia
| | - Antonella Alberici
- Neurology Unit, Department of Neurological Sciences and Vision, ASST-Spedali Civili-University of Brescia, Brescia, Italy
| | - Nigel John Cairns
- College of Medicine and Health and Living Systems Institute, University of Exeter, Exeter, UK
| | - Maurizio Romano
- Department of Life Sciences, Via Valerio 28, University of Trieste, 34127, Trieste, Italy
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34149, Trieste, Italy.
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15
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Tikoo O, Pani P, Pani S. Modulation of energy expenditure independent of contraction: a novel paradigm in muscle. J Physiol 2020; 598:437-439. [DOI: 10.1113/jp279115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ojas Tikoo
- School of Biotechnology, KIIT Bhubaneswar Odisha 751024 India
| | - Punyadhara Pani
- School of Biotechnology, KIIT Bhubaneswar Odisha 751024 India
| | - Sunil Pani
- School of Biotechnology, KIIT Bhubaneswar Odisha 751024 India
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16
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Lee EJ, Kolb J, Hwee DT, Malik FI, Granzier HL. Functional Characterization of the Intact Diaphragm in a Nebulin-Based Nemaline Myopathy (NM) Model-Effects of the Fast Skeletal Muscle Troponin Activator tirasemtiv. Int J Mol Sci 2019; 20:E5008. [PMID: 31658633 PMCID: PMC6829460 DOI: 10.3390/ijms20205008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/05/2019] [Accepted: 10/06/2019] [Indexed: 02/08/2023] Open
Abstract
Respiratory failure due to diaphragm dysfunction is considered a main cause of death in nemaline myopathy (NM) and we studied both isometric force and isotonic shortening of diaphragm muscle in a mouse model of nebulin-based NM (Neb cKO). A large contractile deficit was found in nebulin-deficient intact muscle that is frequency dependent, with the largest deficits at low-intermediate stimulation frequencies (e.g., a deficit of 72% at a stimulation frequency of 20 Hz). The effect of the fast skeletal muscle troponin activator (FSTA) tirasemtiv on force was examined. Tirasemtiv had a negligible effect at maximal stimulation frequencies, but greatly reduced the force deficit of the diaphragm at sub-maximal stimulation levels with an effect that was largest in Neb cKO diaphragm. As a result, the force deficit of Neb cKO diaphragm fell (from 72% to 29% at 20 Hz). Similar effects were found in in vivo experiments on the nerve-stimulated gastrocnemius muscle complex. Load-clamp experiments on diaphragm muscle showed that tirasemtiv increased the shortening velocity, and reduced the deficit in mechanical power by 33%. Thus, tirasemtiv significantly improves muscle function in a mouse model of nebulin-based nemaline myopathy.
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Affiliation(s)
- Eun-Jeong Lee
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA.
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA.
| | - Darren T Hwee
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA 94080, USA.
| | - Fady I Malik
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA 94080, USA.
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA.
- Medical Research Building, RM 325, 1656 E Mabel St, Tucson, AZ 85721, USA.
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17
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Allen DG. Calcium sensitivity and muscle disease. J Physiol 2019; 597:4435-4436. [DOI: 10.1113/jp278471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- David G. Allen
- School of Medical SciencesFaculty of MedicineUniversity of Sydney Australia
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18
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Cheng AJ, Hwee DT, Kim LH, Durham N, Yang HT, Hinken AC, Kennedy AR, Terjung RL, Jasper JR, Malik FI, Westerblad H. Fast skeletal muscle troponin activator CK-2066260 increases fatigue resistance by reducing the energetic cost of muscle contraction. J Physiol 2019; 597:4615-4625. [PMID: 31246276 PMCID: PMC6851859 DOI: 10.1113/jp278235] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 06/26/2019] [Indexed: 01/26/2023] Open
Abstract
Key points Skeletal muscle fatigue limits performance in various physical activities, with exercise intolerance being a key symptom in a broad spectrum of diseases. We investigated whether a small molecule fast skeletal troponin activator (FSTA), CK‐2066260, can mitigate muscle fatigue by reducing the cytosolic free [Ca2+] required to produce a given submaximal force and hence decreasing the energy requirement. Isolated intact single mouse muscle fibres and rat muscles in‐situ treated with CK‐2066260 showed improved muscle endurance., which was accompanied by decreased ATP demand and reduced glycogen usage. CK‐2066260 treatment improved in‐vivo exercise capacity in healthy rats and in a rat model of peripheral artery insufficiency. In conclusion, we show that the FSTA CK‐2066260 effectively counteracts muscle fatigue in rodent skeletal muscle in vitro, in situ, and in vivo. This may translate to humans and provide a promising pharmacological treatment to patients suffering from severe muscle weakness and exercise intolerance.
Abstract Skeletal muscle fatigue limits performance during physical exercise and exacerbated muscle fatigue is a prominent symptom among a broad spectrum of diseases. The present study investigated whether skeletal muscle fatigue is affected by the fast skeletal muscle troponin activator (FSTA) CK‐2066260, which increases myofibrillar Ca2+ sensitivity and amplifies the submaximal force response. Because more force is produced for a given Ca2+, we hypothesized that CK‐2066260 could mitigate muscle fatigue by reducing the energetic cost of muscle activation. Isolated single mouse muscle fibres were fatigued by 100 repeated 350 ms contractions while measuring force and the cytosolic free [Ca2+] or [Mg2+] ([Mg2+]i). When starting fatiguing stimulation at matching forces (i.e. lower stimulation frequency with CK‐2066260): force was decreased by ∼50% with and by ∼75% without CK‐2066260; [Mg2+]i was increased by ∼10% with and ∼32% without CK‐2066260, reflecting a larger decrease in [ATP] in the latter. The glycogen content in in situ stimulated rat muscles fatigued by repeated contractions at matching forces was about two times higher with than without CK‐2066260. Voluntary exercise capacity, assessed by rats performing rotarod exercise and treadmill running, was improved in the presence of CK‐2066260. CK‐2066260 treatment also increased skeletal muscle fatigue resistance and exercise performance in a rat model of peripheral artery insufficiency. In conclusion, we demonstrate that the FSTA CK‐2066260 mitigates skeletal muscle fatigue by reducing the metabolic cost of force generation. Skeletal muscle fatigue limits performance in various physical activities, with exercise intolerance being a key symptom in a broad spectrum of diseases. We investigated whether a small molecule fast skeletal troponin activator (FSTA), CK‐2066260, can mitigate muscle fatigue by reducing the cytosolic free [Ca2+] required to produce a given submaximal force and hence decreasing the energy requirement. Isolated intact single mouse muscle fibres and rat muscles in‐situ treated with CK‐2066260 showed improved muscle endurance., which was accompanied by decreased ATP demand and reduced glycogen usage. CK‐2066260 treatment improved in‐vivo exercise capacity in healthy rats and in a rat model of peripheral artery insufficiency. In conclusion, we show that the FSTA CK‐2066260 effectively counteracts muscle fatigue in rodent skeletal muscle in vitro, in situ, and in vivo. This may translate to humans and provide a promising pharmacological treatment to patients suffering from severe muscle weakness and exercise intolerance.
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Affiliation(s)
- Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Darren T Hwee
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Leo H Kim
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Nickie Durham
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Hsiao T Yang
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Aaron C Hinken
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Adam R Kennedy
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Ronald L Terjung
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Jeffrey R Jasper
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Fady I Malik
- Research and Early Development, Cytokinetics, Inc., South San Francisco, CA, 94080, USA
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
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19
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Marston S. Small molecule studies: the fourth wave of muscle research. J Muscle Res Cell Motil 2019; 40:69-76. [PMID: 31228047 PMCID: PMC6726831 DOI: 10.1007/s10974-019-09526-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 06/13/2019] [Indexed: 12/28/2022]
Abstract
The study of muscle and contractility is an unusual scientific endeavour since it has from the start been focussed on one problem-What makes muscle work?-and yet has needed a vast range of different approaches and techniques to study it. Its uniqueness lies in the fundamental fascination of a large scale molecular machine that converts chemical energy into mechanical energy at ambient temperature and with high efficiency that is also controlled by an exquisitely intricate yet utterly reliable regulatory system and is an essential component of animal life. The investigation of muscle is as innovative as any other field of research. As soon as one approach appears to be played out another comes along. It is instructive to consider this as a series of waves of novel and heightened activity starting in the 1950s. The thesis of this article is that we are approaching the fourth wave with the recent rise of interest in small molecules as research tools and possible therapies for muscle diseases.
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Affiliation(s)
- Steven Marston
- Cardiovascular Division, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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20
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Brazaitis M, Paulauskas H, Eimantas N, Daniuseviciute L, Volungevicius G, Skurvydas A. Motor performance is preserved in healthy aged adults following severe whole-body hyperthermia. Int J Hyperthermia 2018; 36:65-74. [PMID: 30484343 DOI: 10.1080/02656736.2018.1533650] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Healthy aging is associated with a progressive decline in motor performance and thermoregulatory efficiency. Functional consequences of severe whole-body hyperthermia on neurophysiological functions in healthy aged men have not been investigated. To determine whether severe whole-body hyperthermia (increase in rectal temperature of about 2.5 °C) induced by lower-body heating in older men (64-80 years, n = 9) would suppress excitability of reflexes, voluntarily and electrically induced ankle plantar flexor contractile properties were compared with those in young men (19-21 years, n = 11). Though no aging effect on hyperthermia-induced reflex amplitudes was observed, a decrease in maximal H-reflex and V-wave latencies was found to be greater in older than in young men. In older men, lower-body heating was accompanied by a significant increase in twitch and tetani test torque in parallel with a greater decrease in muscle contraction time. There was no temperature-depended aging effect on the voluntary activation and maximal voluntary torque production. Despite delayed and weakened thermoregulation and age-related decline in neuromuscular function, motor performance in whole-body severe hyperthermia is apparently preserved in healthy aging.
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Affiliation(s)
- Marius Brazaitis
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Henrikas Paulauskas
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Nerijus Eimantas
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Laura Daniuseviciute
- b Department of Educational Studies , Kaunas University of Technology , Kaunas , LT , Lithuania
| | - Gintautas Volungevicius
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Albertas Skurvydas
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
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21
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Mechanical isolation, and measurement of force and myoplasmic free [Ca 2+] in fully intact single skeletal muscle fibers. Nat Protoc 2017; 12:1763-1776. [PMID: 28771237 DOI: 10.1038/nprot.2017.056] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mechanical dissection of single intact mammalian skeletal muscle fibers permits real-time measurement of intracellular properties and contractile function of living fibers. A major advantage of mechanical over enzymatic fiber dissociation is that single fibers can be isolated with their tendons remaining attached, which allows contractile forces (in the normal expected range of 300-450 kN/m2) to be measured during electrical stimulation. Furthermore, the sarcolemma of single fibers remains fully intact after mechanical dissection, and hence the living fibers can be studied with intact intracellular milieu and normal function and metabolic properties, as well as ionic control. Given that Ca2+ is the principal regulator of the contractile force, measurements of myoplasmic free [Ca2+] ([Ca2+]i) can be used to further delineate the intrinsic mechanisms underlying changes in skeletal muscle function. [Ca2+]i measurements are most commonly performed in intact single fibers using ratiometric fluorescent indicators such as indo-1 or fura-2. These Ca2+ indicators are introduced into the fiber by pressure injection or by using the membrane-permeable indo-1 AM, and [Ca2+]i is measured by calculating a ratio of the fluorescence at specific wavelengths emitted for the Ca2+-free and Ca2+-bound forms of the dye. We describe here the procedures for mechanical dissection, and for force and [Ca2+]i measurement in intact single fibers from mouse flexor digitorum brevis (FDB) muscle, which is the most commonly used muscle in studies using intact single fibers. This technique can also be used to isolate intact single fibers from various muscles and from various species. As an alternative to Ca2+ indicators, single fibers can also be loaded with fluorescent indicators to measure, for instance, reactive oxygen species, pH, and [Mg2+], or they can be injected with proteins to change functional properties. The entire protocol, from dissection to the start of an experiment on a single fiber, takes ∼3 h.
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