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Reggiani C, Murgia M. Comment on "Fiber-type traps: revisiting common misconceptions about skeletal muscle fiber types with application to motor control, biomechanics, physiology, and biology". J Appl Physiol (1985) 2024; 136:437-438. [PMID: 38353629 DOI: 10.1152/japplphysiol.00008.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 02/16/2024] Open
Affiliation(s)
- Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padua, Italy
- Science and Research Center Koper, Institute for Kinesiology Research, Koper, Slovenia
| | - Marta Murgia
- Department of Biomedical Sciences, University of Padova, Padua, Italy
- Max-Planck-Institute of Biochemistry, Martinsried, Germany
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2
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Shchepkin DV, Nabiev SR, Koubassova NA, Bershitsky SY, Kopylova GV. Comparison of Functional Characteristics of Myosin in Fast and Slow Skeletal Muscles. Bull Exp Biol Med 2020; 169:338-41. [PMID: 32743781 DOI: 10.1007/s10517-020-04882-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 10/23/2022]
Abstract
Myosins of fast and slow skeletal muscles differ by the isoform composition of the heavy and light chains. We compared functional characteristics of myosin from the fast (m. psoas) and slow (m. soleus) muscles of rabbits. The parameters of single actin-myosin interaction were measured in an optical trap, and the characteristics of the Ca2+ regulation of actin-myosin interaction were studied using an in vitro motility assay. The duration of interaction of myosin from the fast muscle with actin was shorter and the filament sliding velocity over this myosin was higher than the corresponding parameters for myosin from the slow muscle. The dependence pCa-velocity for myosin from the fast muscle was less sensitive to Ca2+ than that of slow muscle myosin. Thus, functional properties of myosin determine not only mechanical and kinetic characteristics of muscle contraction, but also the peculiarities of its Ca2+ regulation.
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Sharlo KA, Paramonova II, Lvova ID, Vilchinskaya NA, Bugrova AE, Shevchenko TF, Kalamkarov GR, Shenkman BS. NO-Dependent Mechanisms of Myosin Heavy Chain Transcription Regulation in Rat Soleus Muscle After 7-Days Hindlimb Unloading. Front Physiol 2020; 11:814. [PMID: 32754051 PMCID: PMC7366496 DOI: 10.3389/fphys.2020.00814] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 06/18/2020] [Indexed: 12/27/2022] Open
Abstract
It is known that nitric oxide (NO) may affect myosin heavy chain (MyHC) isoform mRNA transcription in skeletal muscles. The content of NO in soleus muscles decreases during rat hindlimb unloading as well as slow MyHC mRNA transcription. We aimed to detect which signaling pathways are involved in NO-dependent prevention of hindlimb-suspension (HS)-induced changes in MyHCs’ expression pattern. Male Wistar rats were divided into four groups: cage control group (C), hindlimb suspended for 7 days (7HS), hindlimb suspended for 7 days with L-arginine administration (7HS+A) (500 mg/kg body mass), and hindlimb suspended for 7 days with both L-arginine (500 mg/kg) and NO-synthase inhibitor L-NAME administration (50 mg/kg) (7HS+A+N). L-arginine treatment during 7 days of rat HS prevented HS-induced NO content decrease and slow MyHC mRNA transcription decrease and attenuated fast MyHC IIb mRNA transcription increase; it also prevented NFATc1 nuclear content decrease, calsarcin-2 expression increase, and GSK-3β Ser 9 phosphorylation decrease. Moreover, L-arginine administration prevented the HS-induced myh7b and PGC1α mRNAs content decreases and slow-type genes repressor SOX6 mRNA transcription increase. All these slow fiber-type protective effects of L-arginine were blocked in HS+A+N group, indicating that these effects were NO-dependent. Thus, NO decrease prevention during HS restores calcineurin/NFATc1 and myh7b/SOX6 signaling.
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Affiliation(s)
- Kristina A Sharlo
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
| | - Inna I Paramonova
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
| | - Irina D Lvova
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
| | - Natalia A Vilchinskaya
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
| | - Anna E Bugrova
- Neurochemistry Laboratory, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Tatiana F Shevchenko
- Neurochemistry Laboratory, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Grigoriy R Kalamkarov
- Neurochemistry Laboratory, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Boris S Shenkman
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
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Biesiadecki BJ, Brotto MA, Brotto LS, Koch LG, Britton SL, Nosek TM, Jin JP. Rats genetically selected for low and high aerobic capacity exhibit altered soleus muscle myofilament functions. Am J Physiol Cell Physiol 2020; 318:C422-C429. [PMID: 31875694 DOI: 10.1152/ajpcell.00430.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aerobic exercise capacity is critical to bodily health. As a model to investigate the mechanisms that determine health and disease, we employed low (LCR) and high (HCR) capacity running rat models selectively bred to concentrate the genes responsible for divergent aerobic running capacity. To investigate the skeletal muscle contribution to this innate difference in running capacity we employed an approach combining examination of the myofilament protein composition and contractile properties of the fast fiber extensor digitorum longus (EDL) and slow fiber soleus (SOL) muscles from LCR and HCR rats. Intact muscle force experiments demonstrate that SOL, but not EDL, muscles from LCR rats exhibit a three times greater decrease in fatigued force. To investigate the mechanism of this increased fatigability in the LCR SOL muscle, we determined the myofilament protein composition and functional properties. Force-Ca2+ measurements demonstrate decreased Ca2+ sensitivity of single skinned SOL muscle fibers from LCR compared with that of HCR rats. Segregating SOL fibers into fast and slow types demonstrates that the decreased Ca2+ sensitivity in LCR SOL results from a specific decrease in slow-type SOL fiber Ca2+ sensitivity such that it was similar to that of fast-type fibers. These results identify that the altered myofilament contractile properties of LCR SOL slow-type fibers result in a fast muscle type Ca2+ sensitivity and the LCR muscle phenotype. Overall our findings demonstrate alterations of the myofilament proteins could contribute to fatigability of the SOL muscle and the decreased innate aerobic running performance of LCR compared with HCR rats.
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Affiliation(s)
- B J Biesiadecki
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - M A Brotto
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Bone-Muscle Research Center, University of Texas, Arlington, Texas
| | - L S Brotto
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Bone-Muscle Research Center, University of Texas, Arlington, Texas
| | - L G Koch
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - S L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan.,Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - T M Nosek
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - J-P Jin
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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5
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Rejc E, Floreani M, Taboga P, Botter A, Toniolo L, Cancellara L, Narici M, Šimunič B, Pišot R, Biolo G, Passaro A, Rittweger J, Reggiani C, Lazzer S. Loss of maximal explosive power of lower limbs after 2 weeks of disuse and incomplete recovery after retraining in older adults. J Physiol 2018; 596:647-665. [PMID: 29266264 DOI: 10.1113/jp274772] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 12/11/2017] [Indexed: 01/01/2023] Open
Abstract
KEY POINTS Disuse in older adults can critically decrease lower limb muscle power, leading to compromised mobility and overall quality of life. We studied how muscle power and its determinants (muscle mass, single muscle fibre properties and motor control) adapted to 2 weeks of disuse and subsequent 2 weeks of physical training in young and older people. Disuse decreased lower limb muscle power in both groups; however, different adaptations in single muscle fibre properties and co-contraction of leg muscles were observed between young and older individuals. Six physical training sessions performed after disuse promoted the recovery of muscle mass and power. However, they were not sufficient to restore muscle power to pre-disuse values in older individuals, suggesting that further countermeasures are required to counteract the disuse-induced loss of muscle power in older adults. ABSTRACT Disuse-induced loss of muscle power can be detrimental in older individuals, seriously impairing functional capacity. In this study, we examined the changes in maximal explosive power (MEP) of lower limbs induced by a 14-day disuse (bed-rest, BR) and a subsequent 14-day retraining, to assess whether the impact of disuse was greater in older than in young men, and to analyse the causes of such adaptations. Sixteen older adults (Old: 55-65 years) and seven Young (18-30 years) individuals participated in this study. In a subgroup of eight Old subjects, countermeasures based on cognitive training and protein supplementation were applied. MEP was measured with an explosive ergometer, muscle mass was determined by magnetic resonance, motor control was studied by EMG, and single muscle fibres were analysed in vastus lateralis biopsy samples. MEP was ∼33% lower in Old than in Young individuals, and remained significantly lower (-19%) when normalized by muscle volume. BR significantly affected MEP in Old (-15%) but not in Young. Retraining tended to increase MEP; however, this intervention was not sufficient to restore pre-BR values in Old. Ankle co-contraction increased after BR in Old only, and remained elevated after retraining (+30%). Significant atrophy occurred in slow fibres in Old, and in fast fibres in Young. After retraining, the recovery of muscle fibre thickness was partial. The proposed countermeasures were not sufficient to affect muscle mass and power. The greater impact of disuse and smaller retraining-induced recovery observed in Old highlight the importance of designing suitable rehabilitation protocols for older individuals.
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Affiliation(s)
- Enrico Rejc
- Department of Medicine, University of Udine, Udine, Italy.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Mirco Floreani
- Department of Medicine, University of Udine, Udine, Italy.,School of Sport Sciences, University of Udine, Udine, Italy
| | - Paolo Taboga
- Department of Medicine, University of Udine, Udine, Italy.,Department of Kinesiology and Health Science, California State University, Sacramento, CA, USA
| | - Alberto Botter
- Department of Medicine, University of Udine, Udine, Italy.,School of Sport Sciences, University of Udine, Udine, Italy
| | - Luana Toniolo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Lina Cancellara
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marco Narici
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,MRC/ARUK Centre for Musculoskeletal Ageing Research, University of Nottingham, Derby Royal Hospital, Derby, UK
| | - Boštjan Šimunič
- Institute for Kinesiology Research, Science and Research Center of Koper, Koper, Slovenia
| | - Rado Pišot
- Institute for Kinesiology Research, Science and Research Center of Koper, Koper, Slovenia
| | - Gianni Biolo
- Department of Medical Sciences, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Italy
| | - Angelina Passaro
- Department of Medical Sciences, Section of Internal and Cardiorespiratory Medicine, University of Ferrara, Ferrara, Italy
| | - Joern Rittweger
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Stefano Lazzer
- Department of Medicine, University of Udine, Udine, Italy.,School of Sport Sciences, University of Udine, Udine, Italy
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6
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Sofronova SI, Gaynullina DK, Shvetsova AA, Borzykh AA, Selivanova EK, Kostyunina DS, Sharova AP, Martyanov AA, Tarasova OS. Antenatal/early postnatal hypothyroidism alters arterial tone regulation in 2-week-old rats. J Endocrinol 2017; 235:137-151. [PMID: 28794003 DOI: 10.1530/joe-17-0225] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 08/09/2017] [Indexed: 01/05/2023]
Abstract
The mechanisms of vascular alterations resulting from early thyroid hormones deficiency are poorly understood. We tested the hypothesis that antenatal/early postnatal hypothyroidism would alter the activity of endothelial NO pathway and Rho-kinase pathway, which are specific for developing vasculature. Dams were treated with propylthiouracil (PTU, 7 ppm) in drinking water during gestation and 2 weeks after delivery, and their progeny had normal body weight but markedly reduced blood levels of thyroid hormones (ELISA). Small arteries from 2-week-old male pups were studied using wire myography, qPCR and Western blotting. Mesenteric arteries of PTU pups, compared to controls, demonstrated smaller maximum response to α1-adrenergic agonist methoxamine and reduced mRNA contents of smooth muscle differentiation markers α-actin and SERCA2A. Inhibition of basal NO synthesis by l-NNA led to tonic contraction of mesenteric arteries and augmented their contractile responses to methoxamine; both l-NNA effects were impaired in PTU pups. PTU pups demonstrated lower blood level of NO metabolites compared to control group (Griess reaction). Rho-kinase inhibitor Y27632 strongly reduced mesenteric arteries responses to methoxamine in PTU pups, that was accompanied by elevated Rho-kinase content in their arteries in comparison to control ones. Unlike mesenteric, saphenous arteries of PTU pups, compared to controls, had no changes in α-actin and SERCA2A contents and in responses to l-NNA and Y27632. In conclusion, thyroid hormones deficiency suppresses the anticontractile effect of NO and potentiates the procontractile Rho-kinase effects in mesenteric arteries of 2-week-old pups. Such alterations disturb perinatal cardiovascular homeostasis and might lead to cardiovascular pathologies in adulthood.
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Affiliation(s)
- Svetlana I Sofronova
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
| | - Dina K Gaynullina
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
- Department of PhysiologyRussian National Research Medical University, Moscow, Russia
| | - Anastasia A Shvetsova
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
| | - Anna A Borzykh
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
| | - Ekaterina K Selivanova
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
| | - Daria S Kostyunina
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
| | - Anna P Sharova
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
| | - Andrey A Martyanov
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
| | - Olga S Tarasova
- Institute for Biomedical ProblemsRussian Academy of Sciences, Moscow, Russia
- Faculty of BiologyM.V. Lomonosov Moscow State University, Moscow, Russia
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7
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Clayton JE, Pollard LW, Murray GG, Lord M. Myosin motor isoforms direct specification of actomyosin function by tropomyosins. Cytoskeleton (Hoboken) 2015; 72:131-45. [PMID: 25712463 DOI: 10.1002/cm.21213] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 01/18/2015] [Accepted: 01/26/2015] [Indexed: 11/08/2022]
Abstract
Myosins and tropomyosins represent two cytoskeletal proteins that often work together with actin filaments in contractile and motile cellular processes. While the specialized role of tropomyosin in striated muscle myosin-II regulation is well characterized, its role in nonmuscle myosin regulation is poorly understood. We previously showed that fission yeast tropomyosin (Cdc8p) positively regulates myosin-II (Myo2p) and myosin-V (Myo52p) motors. To understand the broader implications of this regulation we examined the role of two mammalian tropomyosins (Tpm3.1cy/Tm5NM1 and Tpm4.2cy/Tm4) recently implicated in cancer cell proliferation and metastasis. Like Cdc8p, the Tpm3.1cy and Tpm4.2cy isoforms significantly enhance Myo2p and Myo52p motor activity, converting nonprocessive Myo52p molecules into processive motors that can walk along actin tracks as single molecules. In contrast to the positive regulation of Myo2p and Myo52p, Cdc8p and the mammalian tropomyosins potently inhibited skeletal muscle myosin-II, while having negligible effects on the highly processive mammalian myosin-Va. In support of a conserved role for certain tropomyosins in regulating nonmuscle actomyosin structures, Tpm3.1cy supported normal contractile ring function in fission yeast. Our work reveals that actomyosin regulation by tropomyosin is dependent on the myosin isoform, highlighting a general role for specific isoforms of tropomyosin in sorting myosin motor outputs.
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Affiliation(s)
- Joseph E Clayton
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont, United States of America
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Maffei M, Longa E, Qaisar R, Agoni V, Desaphy JF, Camerino DC, Bottinelli R, Canepari M. Actin sliding velocity on pure myosin isoforms from hindlimb unloaded mice. Acta Physiol (Oxf) 2014; 212:316-29. [PMID: 24888432 DOI: 10.1111/apha.12320] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 05/07/2014] [Accepted: 05/25/2014] [Indexed: 11/29/2022]
Abstract
AIM Notwithstanding the widely accepted idea that following disuse skeletal muscles become faster, an increase in shortening velocity was previously observed mostly in fibres containing type 1 myosin, whereas a decrease was generally found in fibres containing type 2B myosin. In this study, unloaded shortening velocity of pure type 1 and 2B fibres from hindlimb unloaded mice was determined and a decrease in type 2B fibres was found. METHODS To clarify whether the decrease in shortening velocity could depend on alterations of myosin motor function, an in vitro motility assay approach was applied to study pure type 1 and pure type 2B myosin from hindlimb unloaded mice. The latter approach, assessing actin sliding velocity on isolated myosin in the absence of other myofibrillar proteins, enabled to directly investigate myosin motor function. RESULTS Actin sliding velocity was significantly lower on type 2B myosin following unloading (2.70 ± 0.32 μm s(-1)) than in control conditions (4.11 ± 0.35 μm s(-1)), whereas actin sliding velocity of type 1 myosin was not different following unloading (0.89 ± 0.04 μm s(-1)) compared with control conditions (0.84 ± 0.17 μm s(-1)). Myosin light chain (MLC) isoform composition of type 2B myosin from hindlimb unloaded and control mice was not different. No oxidation of either type 1 or 2B myosin was observed. Higher phosphorylation of regulatory MLC in type 2B myosin after unloading was found. CONCLUSION Results suggest that the observed lower shortening velocity of type 2B fibres following unloading could be related to slowing of acto-myosin kinetics in the presence of MLC phosphorylation.
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Affiliation(s)
- M. Maffei
- Department of Molecular Medicine and Interuniversity; Institute of Myology; University of Pavia; Pavia Italy
| | - E. Longa
- Department of Molecular Medicine and Interuniversity; Institute of Myology; University of Pavia; Pavia Italy
| | - R. Qaisar
- Department of Molecular Medicine and Interuniversity; Institute of Myology; University of Pavia; Pavia Italy
| | - V. Agoni
- Department of Molecular Medicine and Interuniversity; Institute of Myology; University of Pavia; Pavia Italy
| | - J.-F. Desaphy
- Section of Pharmacology; Department of Pharmacy and Drug Sciences and Interuniversity Institute of Myology; University of Bari - Aldo Moro; Bari Italy
| | - D. Conte Camerino
- Section of Pharmacology; Department of Pharmacy and Drug Sciences and Interuniversity Institute of Myology; University of Bari - Aldo Moro; Bari Italy
| | - R. Bottinelli
- Department of Molecular Medicine and Interuniversity; Institute of Myology; University of Pavia; Pavia Italy
- Fondazione Salvatore Maugeri (IRCCS); Scientific Institute of Pavia; Pavia Italy
- Interdipartimental Centre of Biology and Sport Medicine; University of Pavia; Pavia Italy
| | - M. Canepari
- Department of Molecular Medicine and Interuniversity; Institute of Myology; University of Pavia; Pavia Italy
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9
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Taskin S, Stumpf VI, Bachmann J, Weber C, Martignoni ME, Friedrich O. Motor protein function in skeletal abdominal muscle of cachectic cancer patients. J Cell Mol Med 2013; 18:69-79. [PMID: 24251822 PMCID: PMC3916119 DOI: 10.1111/jcmm.12165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 09/16/2013] [Indexed: 01/06/2023] Open
Abstract
Cachexia presents with ongoing muscle wasting, altering quality of life in cancer patients. Cachexia is a limiting prognostic factor for patient survival and health care costs. Although animal models and human trials have shown mechanisms of motorprotein proteolysis, not much is known about intrinsic changes of muscle functionality in cancer patients suffering from muscle cachexia, and deeper insights into cachexia pathology in humans are needed. To address this question, rectus abdominis muscle samples were collected from several surgical control, non-cachectic and cachectic cancer patients and processed for skinned fibre biomechanics, molecular in vitro motility assays, myosin isoform protein compositions and quantitative ubiquitin polymer protein analysis. In pre-cachectic and cachectic cancer patient samples, maximum force was significantly compromised compared with controls, but showed an unexpected increase in myofibrillar Ca2+ sensitivity consistent with a shift from slow to fast myosin isoform expression seen in SDS-PAGE analysis and in vitro motility assays. Force deficit was specific for ‘cancer’, but not linked to presence of cachexia. Interestingly, quantitative ubiquitin immunoassays revealed no major changes in static ubiquitin polymer protein profiles, whether cachexia was present or not and were shown to mirror profiles in control patients. Our study on muscle function in cachectic patients shows that abdominal wall skeletal muscle in cancer cachexia shows signs of weakness that can be partially attributed to intrinsic changes to contractile motorprotein function. On protein levels, static ubiquitin polymeric distributions were unaltered, pointing towards evenly up-regulated ubiquitin protein turnover with respect to ubiquitin conjugation, proteasome degradation and de-ubiquitination.
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Affiliation(s)
- Sultan Taskin
- Institute of Physiology and Pathophysiology, Ruprecht-Karls-University, Heidelberg, Germany
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10
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Baldwin KM, Haddad F, Pandorf CE, Roy RR, Edgerton VR. Alterations in muscle mass and contractile phenotype in response to unloading models: role of transcriptional/pretranslational mechanisms. Front Physiol 2013; 4:284. [PMID: 24130531 PMCID: PMC3795307 DOI: 10.3389/fphys.2013.00284] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 09/18/2013] [Indexed: 01/30/2023] Open
Abstract
Skeletal muscle is the largest organ system in mammalian organisms providing postural control and movement patterns of varying intensity. Through evolution, skeletal muscle fibers have evolved into three phenotype clusters defined as a motor unit which consists of all muscle fibers innervated by a single motoneuron linking varying numbers of fibers of similar phenotype. This fundamental organization of the motor unit reflects the fact that there is a remarkable interdependence of gene regulation between the motoneurons and the muscle mainly via activity-dependent mechanisms. These fiber types can be classified via the primary type of myosin heavy chain (MHC) gene expressed in the motor unit. Four MHC gene encoded proteins have been identified in striated muscle: slow type I MHC and three fast MHC types, IIa, IIx, and IIb. These MHCs dictate the intrinsic contraction speed of the myofiber with the type I generating the slowest and IIb the fastest contractile speed. Over the last ~35 years, a large body of knowledge suggests that altered loading state cause both fiber atrophy/wasting and a slow to fast shift in the contractile phenotype in the target muscle(s). Hence, this review will examine findings from three different animal models of unloading: (1) space flight (SF), i.e., microgravity; (2) hindlimb suspension (HS), a procedure that chronically eliminates weight bearing of the lower limbs; and (3) spinal cord isolation (SI), a surgical procedure that eliminates neural activation of the motoneurons and associated muscles while maintaining neurotrophic motoneuron-muscle connectivity. The collective findings demonstrate: (1) all three models show a similar pattern of fiber atrophy with differences mainly in the magnitude and kinetics of alteration; (2) transcriptional/pretranslational processes play a major role in both the atrophy process and phenotype shifts; and (3) signaling pathways impacting these alterations appear to be similar in each of the models investigated.
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Affiliation(s)
- Kenneth M Baldwin
- Department of Physiology and Biophysics, University of California, Irvine, Irvine CA, USA
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11
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Abstract
To explore the molecular mechanisms responsible for the variation in smooth muscle contractile kinetics, the influence of MgATP, MgADP, and inorganic phosphate (P(i)) on force and shortening velocity in thiophosphorylated "fast" (taenia coli: maximal shortening velocity Vmax = 0.11 ML/s) and "slow" (aorta: Vmax = 0.015 ML/s) smooth muscle from the guinea pig were compared. P(i) inhibited active force with minor effects on the V(max). In the taenia coli, 20 mM P(i) inhibited force by 25%. In the aorta, the effect was markedly less (< 10%), suggesting differences between fast and slow smooth muscles in the binding of P(i) or in the relative population of P(i) binding states during cycling. Lowering of MgATP reduced force and V(max). The aorta was less sensitive to reduction in MgATP (Km for Vmax: 80 microM) than the taenia coli (Km for Vmax: 350 microM). Thus, velocity is controlled by steps preceding the ATP binding and cross-bridge dissociation, and a weaker binding of ATP is not responsible for the lower V(max) in the slow muscle. MgADP inhibited force and V(max). Saturating concentrations of ADP did not completely inhibit maximal shortening velocity. The effect of ADP on Vmax was observed at lower concentrations in the aorta compared with the taenia coli, suggesting that the ADP binding to phosphorylated and cycling cross-bridges is stronger in slow compared with fast smooth muscle.
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Affiliation(s)
- Mia Löfgren
- Department of Physiological Sciences, Lund University, Tornavägen 10, BMC F11, S-22184 Lund, Sweden
| | - Ulf Malmqvist
- Department of Physiological Sciences, Lund University, Tornavägen 10, BMC F11, S-22184 Lund, Sweden
| | - Anders Arner
- Department of Physiological Sciences, Lund University, Tornavägen 10, BMC F11, S-22184 Lund, Sweden
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12
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Abstract
We describe a simple technique for maintaining highly contractile long-term chicken myogenic cultures on Matrigel, a gel composed of basement membrane components extracted from the Engelbreth-Holm-Swarm mouse tumor. Cultures grown on Matrigel consist of three-dimensional multilayers of cylindrical, contracting myotubes which endure for at least 60 d without myotube detachment. A Matrigel substrate increases the initial plating efficiency but does not effect cell proliferation. Large-scale differentiation in cultures maintained on Matrigel is delayed by 1 to 2 d, compared to cultures grown on gelatin-coated dishes. Long-term maintenance on Matrigel also results in increased expression of the neonatal and adult fast myosin heavy chain isoforms. Culturing of cells on a Matrigel substrate could thus facilitate the study of later events of in vitro myogenesis.
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Affiliation(s)
- R S Hartley
- Department of Biological Structure, School of Medicine, University of Washington, Seattle 98195
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