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Hoh JFY. Developmental, physiologic and phylogenetic perspectives on the expression and regulation of myosin heavy chains in mammalian skeletal muscles. J Comp Physiol B 2023:10.1007/s00360-023-01499-0. [PMID: 37277594 DOI: 10.1007/s00360-023-01499-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 05/05/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023]
Abstract
The kinetics of myosin controls the speed and power of muscle contraction. Mammalian skeletal muscles express twelve kinetically different myosin heavy chain (MyHC) genes which provides a wide range of muscle speeds to meet different functional demands. Myogenic progenitors from diverse craniofacial and somitic mesoderm specify muscle allotypes with different repertoires for MyHC expression. This review provides a brief synopsis on the historical and current views on how cell lineage, neural impulse patterns, and thyroid hormone influence MyHC gene expression in muscles of the limb allotype during development and in adult life and the molecular mechanisms thereof. During somitic myogenesis, embryonic and foetal myoblast lineages form slow and fast primary and secondary myotube ontotypes which respond differently to postnatal neural and thyroidal influences to generate fully differentiated fibre phenotypes. Fibres of a given phenotype may arise from myotubes of different ontotypes which retain their capacity to respond differently to neural and thyroidal influences during postnatal life. This gives muscles physiological plasticity to adapt to fluctuations in thyroid hormone levels and patterns of use. The kinetics of MyHC isoforms vary inversely with animal body mass. Fast 2b fibres are specifically absent in muscles involved in elastic energy saving in hopping marsupials and generally absent in large eutherian mammals. Changes in MyHC expression are viewed in the context of the physiology of the whole animal. The roles of myoblast lineage and thyroid hormone in regulating MyHC gene expression are phylogenetically the most ancient while that of neural impulse patterns the most recent.
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Affiliation(s)
- Joseph Foon Yoong Hoh
- Discipline of Physiology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia.
- , PO Box 152, Killara, NSW, 2071, Australia.
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Kawata M, Luziga C, Miyata H, Sugiura T, Wada N. Differential expression of myosin heavy chain isoforms type II in skeletal muscles of polar and black bears. Anat Histol Embryol 2022; 52:363-372. [PMID: 36471656 DOI: 10.1111/ahe.12893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 10/24/2022] [Accepted: 11/19/2022] [Indexed: 12/12/2022]
Abstract
In this study, the pattern of myosin heavy chain (MHC) isoforms expression in skeletal muscles of the trunk, forelimb and hindlimb in Polar Bear (PB) Ursus maritimus; American Black Bear (AmBB), Ursus americanus and Asian Black Bear (AsBB), Ursus thibetanus was analysed by immunohistochemistry and SDS-PAGE. Results showed that slow (MHC-I) and fast (MHC-II) isoforms exist in muscles of bears. Type II fibres were classified further into Type IIa and IIx in PB but not in AsBB and AmBB. The distribution of Type I and Type II fibres in the trunk, forelimb and hindlimb varied based on muscle type and animal species. The proportions of Type I fibres formed approximately one-third of muscle composition in PB (trunk, 32.0%; forelimb, 34.7%; hindlimb, 34.5%) and a half in both AsBB and AmBB whereas Type IIa and IIx formed approximately two-third in PB (trunk, 68.0%; forelimb, 65.3%; hindlimb, 65.5%) and a half of Type II in both AmBB and AsBB. PB is a good swimmer, lives in Arctic Ocean on slippery ice catching aquatic mammals such as seals and is larger in size compared to the medium sized AmBB (living in forest) and AsBB (arboreal). The results suggest that in bears, there is greater diversity in MHC isoforms II, being expressed in selected fast contracting skeletal muscles in response to variety of environments, weight bearing and locomotion.
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Affiliation(s)
- Mutsumi Kawata
- The United Veterinary Graduated School, Yamaguchi University, Yamaguchi City, Japan
| | - Claudius Luziga
- Department of Veterinary Anatomy and Pathology, College of Veterinary and Biomedical Sciences, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Hirofumi Miyata
- Department of Biological Sciences, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Takao Sugiura
- Laboratory of Biomechanics and Physiology, Faculty of Liberal Arts, Yamaguchi University, Yamaguchi, Japan
| | - Naomi Wada
- Department of System Physiology, Yamaguchi University, Yamaguchi City, Japan
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Fuller AM, DeVine A, Murazzi I, Mason NJ, Weber K, Eisinger-Mathason TSK. Comparative oncology reveals DNMT3B as a molecular vulnerability in undifferentiated pleomorphic sarcoma. Cell Oncol (Dordr) 2022; 45:1277-1295. [PMID: 36181640 PMCID: PMC9772002 DOI: 10.1007/s13402-022-00717-1] [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] [Accepted: 09/06/2022] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Undifferentiated pleomorphic sarcoma (UPS), an aggressive subtype of soft-tissue sarcoma (STS), is exceedingly rare in humans and lacks effective, well-tolerated therapies. In contrast, STS are relatively common in canine companion animals. Thus, incorporation of veterinary patients into studies of UPS offers an exciting opportunity to develop novel therapeutic strategies for this rare human disease. Genome-wide studies have demonstrated that UPS is characterized by aberrant patterns of DNA methylation. However, the mechanisms and impact of this epigenetic modification on UPS biology and clinical behavior are poorly understood. METHODS DNA methylation in mammalian cells is catalyzed by the canonical DNA methyltransferases DNMT1, DNMT3A and DNMT3B. Therefore, we leveraged cell lines and tissue specimens from human and canine patients, together with an orthotopic murine model, to probe the functional and clinical significance of DNMTs in UPS. RESULTS We found that the DNA methyltransferase DNMT3B is overexpressed in UPS relative to normal mesenchymal tissues and is associated with a poor prognosis. Consistent with these findings, genetic DNMT3B depletion strongly inhibited UPS cell proliferation and tumor progression. However, existing hypomethylating agents, including the clinically approved drug 5-aza-2'-deoxycytidine (DAC) and the DNMT3B-inhibiting tool compound nanaomycin A, were ineffective in UPS due to cellular uptake and toxicity issues. CONCLUSIONS DNMT3B represents a promising molecular susceptibility in UPS, but further development of DNMT3B-targeting strategies for these patients is required.
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Affiliation(s)
- Ashley M Fuller
- Abramson Family Cancer Research Institute, Department of Pathology and Laboratory Medicine, Penn Sarcoma Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ann DeVine
- Abramson Family Cancer Research Institute, Department of Pathology and Laboratory Medicine, Penn Sarcoma Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ileana Murazzi
- Abramson Family Cancer Research Institute, Department of Pathology and Laboratory Medicine, Penn Sarcoma Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nicola J Mason
- Department of Clinical Sciences and Advanced Medicine, Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kristy Weber
- Penn Sarcoma Program, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - T S Karin Eisinger-Mathason
- Abramson Family Cancer Research Institute, Department of Pathology and Laboratory Medicine, Penn Sarcoma Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Hakim CH, Yang HT, Burke MJ, Teixeira J, Jenkins GJ, Yang NN, Yao G, Duan D. Extensor carpi ulnaris muscle shows unexpected slow-to-fast fiber type switch in Duchenne muscular dystrophy dogs. Dis Model Mech 2021; 14:273743. [PMID: 34704592 PMCID: PMC8688408 DOI: 10.1242/dmm.049006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 10/20/2021] [Indexed: 11/22/2022] Open
Abstract
Aged dystrophin-null canines are excellent models for studying experimental therapies for Duchenne muscular dystrophy, a lethal muscle disease caused by dystrophin deficiency. To establish the baseline, we studied the extensor carpi ulnaris (ECU) muscle in 15 terminal age (3-year-old) male affected dogs and 15 age/sex-matched normal dogs. Affected dogs showed histological and anatomical hallmarks of dystrophy, including muscle inflammation and fibrosis, myofiber size variation and centralized myonuclei, as well as a significant reduction of muscle weight, muscle-to-body weight ratio and muscle cross-sectional area. To rigorously characterize the contractile properties of the ECU muscle, we developed a novel in situ assay. Twitch and tetanic force, contraction and relaxation rate, and resistance to eccentric contraction-induced force loss were significantly decreased in affected dogs. Intriguingly, the time-to-peak tension and half-relaxation time were significantly shortened in affected dogs. Contractile kinetics predicted an unforeseen slow-to-fast myofiber-type switch, which we confirmed at the protein and transcript level. Our study establishes a foundation for studying long-term and late-stage therapeutic interventions in dystrophic canines. The unexpected myofiber-type switch highlights the complexity of muscle remodeling in dystrophic large mammals. This article has an associated First Person interview with the first author of the paper. Summary: A slow-to-fast fiber-type switch in dystrophic canine ECU muscle is revealed by contraction kinetics and myosin protein and transcript expression. This highlights the complexity of muscle remodeling in Duchenne muscular dystrophy.
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Affiliation(s)
- Chady H Hakim
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA.,National Center for Advancing Translational Sciences, NIH, Bethesda, MD, USA
| | - Hsiao T Yang
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA
| | - Matthew J Burke
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA
| | - James Teixeira
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA
| | - Gregory J Jenkins
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA
| | - N N Yang
- National Center for Advancing Translational Sciences, NIH, Bethesda, MD, USA
| | - Gang Yao
- Department of Biomedical, Biological & Chemical Engineering, College of Engineering, The University of Missouri, Columbia, MO, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA.,Department of Biomedical, Biological & Chemical Engineering, College of Engineering, The University of Missouri, Columbia, MO, USA.,Department of Neurology, School of Medicine, The University of Missouri, Columbia, MO, USA.,Department of Biomedical Sciences, College of Veterinary Medicine, The University of Missouri, Columbia, MO, USA
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Noninvasive technique to evaluate the muscle fiber characteristics using q-space imaging. PLoS One 2019; 14:e0214805. [PMID: 30947237 PMCID: PMC6449066 DOI: 10.1371/journal.pone.0214805] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 03/20/2019] [Indexed: 01/23/2023] Open
Abstract
Background Skeletal muscles include fast and slow muscle fibers. The tibialis anterior muscle (TA) is mainly composed of fast muscle fibers, whereas the soleus muscle (SOL) is mainly composed of slow muscle fibers. However, a noninvasive approach for appropriately investigating the characteristics of muscles is not available. Monitoring of skeletal muscle characteristics can help in the evaluation of the effects of strength training and diseases on skeletal muscles. Purpose The present study aimed to determine whether q-space imaging can distinguish between TA and SOL in in vivo mice. Methods In vivo magnetic resonance imaging of the right calves of mice (n = 8) was performed using a 7-Tesla magnetic resonance imaging system with a cryogenic probe. TA and SOL were assessed. q-space imaging was performed with a field of view of 10 mm × 10 mm, matrix of 48 × 48, and section thickness of 1000 μm. There were ten b-values ranging from 0 to 4244 s/mm2, and each b-value had diffusion encoding in three directions. Magnetic resonance imaging findings were compared with immunohistological findings. Results Full width at half maximum and Kurtosis maps of q-space imaging showed signal intensities consistent with immunohistological findings for both fast (myosin heavy chain II) and slow (myosin heavy chain I) muscle fibers. With regard to quantification, both full width at half maximum and Kurtosis could represent the immunohistological findings that the cell diameter of TA was larger than that of SOL (P < 0.01). Conclusion q-space imaging could clearly differentiate TA from SOL using differences in cell diameters. This technique is a promising method to noninvasively estimate the fiber type ratio in skeletal muscles, and it can be further developed as an indicator of muscle characteristics.
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Effect of ageing on the myosin heavy chain composition of the human sternocleidomastoid muscle. Ann Anat 2018; 216:95-99. [DOI: 10.1016/j.aanat.2017.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 11/19/2017] [Accepted: 12/14/2017] [Indexed: 11/18/2022]
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Ragionieri L, Ivanovska A, Pendovski L, Ravanetti F, Botti M, Gazza F, Cacchioli A. Influence of genetic selection on the myofibre type composition of porcine biceps femoris muscle: a comparative study of a purebred (Nero di Parma) and commercial hybrid pigs (Large White × Landrace × Duroc). ZOOMORPHOLOGY 2017. [DOI: 10.1007/s00435-017-0346-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Size and Proportions of Slow-Twitch and Fast-Twitch Muscle Fibers in Human Costal Diaphragm. BIOMED RESEARCH INTERNATIONAL 2016; 2016:5946520. [PMID: 27891518 PMCID: PMC5116518 DOI: 10.1155/2016/5946520] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/17/2016] [Indexed: 11/18/2022]
Abstract
Smaller diaphragmatic motor unit potentials (MUPs) compared to MUPs of limb muscles lead to the hypothesis that diaphragmatic muscle fibers, being the generators of MUPs, might be also smaller. We compared autopsy samples of costal diaphragm and vastus lateralis of healthy men with respect to fibers' size and expression of slow myosin heavy chain isoform (MyHC-1) and fast 2A isoform (MyHC-2A). Diaphragmatic fibers were smaller than fibers in vastus lateralis with regard to the mean minimal fiber diameter of slow-twitch (46.8 versus 72.2 μm, p < 0.001), fast-twitch (45.1 versus 62.4 μm, p < 0.001), and hybrid fibers (47.3 versus 65.0 μm, p < 0.01) as well as to the mean fiber cross-sectional areas of slow-twitch (2376.0 versus 5455.9 μm2, p < 0.001), fast-twitch (2258.7 versus 4189.7 μm2, p < 0.001), and hybrid fibers (2404.4 versus 4776.3 μm2, p < 0.01). The numerical proportion of slow-twitch fibers was higher (50.2 versus 36.3%, p < 0.01) in costal diaphragm and the numerical proportion of fast-twitch fibers (47.2 versus 58.7%, p < 0.01) was lower. The numerical proportion of hybrid fibers did not differ. Muscle fibers of costal diaphragm have specific characteristics which support increased resistance of diaphragm to fatigue.
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Smerdu V, Cvetko E. Myosin heavy chain-2b transcripts and isoform are expressed in human laryngeal muscles. Cells Tissues Organs 2013; 198:75-86. [PMID: 23796659 DOI: 10.1159/000351293] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2013] [Indexed: 11/19/2022] Open
Abstract
Three fast myosin heavy chain (MyHC) isoforms, i.e. MyHC-2a, -2x and -2b, are expressed in skeletal muscles of smaller mammals. In contrast, only MyHC-2a and -2x have been revealed in humans so far. The expression of MyHC isoforms is known to be wider in the functionally more specialized laryngeal muscles. Though mRNA transcripts of the MyHC-2b gene were found to be expressed in certain human skeletal and laryngeal muscles, the corresponding isoform has not been demonstrated in these muscles. To our knowledge, we are the first to demonstrate not only the expression of MyHC-2b transcripts using an in situ hybridization technique but also the corresponding protein, i.e. the MyHC-2b isoform, in some human laryngeal muscles by immunohistochemistry but not by polyacrylamide gel electrophoresis. Using a set of antibodies specific to MyHC isoforms, we demonstrated that MyHC-2b was always co-expressed with the major MyHC isoforms, not only with the fast ones (MyHC-2a and -2x) but with the slow isoform (MyHC-1) as well.
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Affiliation(s)
- Vika Smerdu
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia.
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Sánchez-Collado C, Vázquez JM, Rivero MA, Martínez F, Ramírez G, Gil F. Distribution Pattern of Muscle Fibre Types In Soft Palate of the Dog (Canis familiaris,L.). Anat Histol Embryol 2013; 43:56-63. [DOI: 10.1111/ahe.12048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/02/2013] [Indexed: 11/28/2022]
Affiliation(s)
- C. Sánchez-Collado
- Department of Anatomy and Compared Pathological Anatomy; Faculty of Veterinary; Universidad de Murcia; 30100 Murcia Spain
| | - J. M. Vázquez
- Department of Anatomy and Compared Pathological Anatomy; Faculty of Veterinary; Universidad de Murcia; 30100 Murcia Spain
| | - M. A. Rivero
- Department of Morphology; Faculty of Veterinary; Universidad de Las Palmas de Gran Canaria; 35413 Las Palmas de G.C Spain
| | - F. Martínez
- Department of Anatomy and Compared Pathological Anatomy; Faculty of Veterinary; Universidad de Murcia; 30100 Murcia Spain
| | - G. Ramírez
- Department of Anatomy and Compared Pathological Anatomy; Faculty of Veterinary; Universidad de Murcia; 30100 Murcia Spain
| | - F. Gil
- Department of Anatomy and Compared Pathological Anatomy; Faculty of Veterinary; Universidad de Murcia; 30100 Murcia Spain
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Kohn TA, Curry JW, Noakes TD. Black wildebeest skeletal muscle exhibits high oxidative capacity and a high proportion of type IIx fibres. ACTA ACUST UNITED AC 2012; 214:4041-7. [PMID: 22071196 DOI: 10.1242/jeb.061572] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of the study was to investigate the skeletal muscle characteristics of black wildebeest (Connochaetes gnou) in terms of fibre type and metabolism. Samples were obtained post mortem from the vastus lateralis and longissimus lumborum muscles and analysed for myosin heavy chain (MHC) content. Citrate synthase (CS), 3-hydroxyacyl co A dehydrogenase (3HAD), phosphofructokinase (PFK), lactate dehydrogenase (LDH) and creatine kinase (CK) activities were measured spectrophotometrically to represent the major metabolic pathways in these muscles. Both muscles had less than 20% MHC I, whereas MHC IIa and MHC IIx were expressed in excess of 50% in the vastus lateralis and longissimus lumborum muscles, respectively. Overall fibre size was 2675±1034 μm(2), which is small compared with other species. Oxidative capacity (CS and 3HAD) in both muscles was high and did not differ from one another, but the longissimus lumborum had significantly (P<0.05) higher PFK, LDH and CK activities. No relationships were observed between fibre type and the oxidative and oxygen-independent metabolic capacity as measured by specific enzyme activities. This study confirms the presence of both fast-twitch fibres and high oxidative capacity in black wildebeest, indicating an animal that can run very fast but is also fatigue resistant.
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Affiliation(s)
- Tertius Abraham Kohn
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Newlands, South Africa.
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Lefaucheur L. A second look into fibre typing – Relation to meat quality. Meat Sci 2010; 84:257-70. [DOI: 10.1016/j.meatsci.2009.05.004] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 04/16/2009] [Accepted: 05/03/2009] [Indexed: 12/25/2022]
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Glaser BW, You G, Zhang M, Medler S. Relative proportions of hybrid fibres are unaffected by 6 weeks of running exercise in mouse skeletal muscles. Exp Physiol 2009; 95:211-21. [DOI: 10.1113/expphysiol.2009.049023] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Stirn Kranjc B, Smerdu V, Erzen I. Histochemical and immunohistochemical profile of human and rat ocular medial rectus muscles. Graefes Arch Clin Exp Ophthalmol 2009; 247:1505-15. [PMID: 19609551 PMCID: PMC2758108 DOI: 10.1007/s00417-009-1128-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 06/15/2009] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To compare the organization of human and rat ocular medial recti muscles (MR). METHODS The cryosections of human and rat MR were processed for myofibrillar ATPase (mATPase), succinate dehydrogenase and glycerol-3-phosphate dehydrogenase. To reveal myosin heavy chain (MyHC) isoforms, specific monoclonal antibodies against MyHC-1/beta- slow, alpha-cardiac (-alpha), -2a, -2x, -2b, -extraocular (eom), -embryonic (-emb) and -neonatal (-neo) were applied. The MyHC gene expression was studied by in situ hybridization in human muscle. RESULTS The muscle fibers were arranged in two distinct layers in both species. In the orbital layer most fibers were highly oxidative and expressed fast MyHC isoforms, whereas slow and oxidative fibers expressed MyHC-1 and -alpha, some of them also MyHC-2a, -2x, -eom, very rarely -emb, and -neo. In the global layer, slow fibers with very low oxidative and glycolytic activity and three types of fast fibers, glycolytic, oxidative and oxidative-glycolytic, could be distinguished. The slow medium-sized fibers with mATPase activity stable at pH 4.4 expressed mostly MyHC-1 and -alpha in rat, while in humans they co-expressed MyHC-1 with -2b, -2x, -eom, and -neo. In both species, the fast fibers showed variable mATPase activity after preincubation at pH 9.4, and co-expressed various combinations of MyHC-2b, -2x, -2a and -eom but not -emb and -neo. MyHC-2b expressing fibers were larger and glycolytic, while MyHC-2a expressing fibers were smaller and highly oxidative in both species. To our knowledge, the present study is the first that demonstrated the expression of MyHC-2b in any of human skeletal muscles. Though the expression of MyHC genes did not correlate with the immunohistochemical profile of fibers in human MR, the expression of MyHC-2b gene was undoubtedly confirmed. CONCLUSIONS Rat MR represent a good model that can be applied to study human MR in experiment or disease, however certain differences are to be expected due to specific oculomotor demands in humans.
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Affiliation(s)
- Branka Stirn Kranjc
- University Medical Centre, University Eye Hospital Ljubljana, Ljubljana, Slovenia.
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Smerdu V, Cehovin T, Strbenc M, Fazarinc G. Enzyme- and immunohistochemical aspects of skeletal muscle fibers in brown bear (Ursus arctos). J Morphol 2009; 270:154-61. [PMID: 18798247 DOI: 10.1002/jmor.10673] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To further elucidate the pattern of MHC isoform expression in skeletal muscles of large mammals, in this study the skeletal muscles of brown bear, one of the largest mammalian predators with an extraordinary locomotor capacity, were analyzed. Fiber types in longissimus dorsi, triceps brachii caput longum, and rectus femoris muscles were determined according to the myofibrillar ATPase (mATPase) histochemistry and MHC isoform expression, revealed by a set of antibodies specific to MHC isoforms. The oxidative (SDH) and glycolytic enzyme (alpha-GPDH) capacity of fibers was demonstrated as well. By mATPase histochemistry five fiber types, i.e., I, IIC, IIA, IIAX, IIX were distinguished. Analyzing the MHC isoform expression, we assume that MHC-I, -IIa, and -IIx are expressed in the muscles of adolescent bears. MHC-I isoform was expressed in Type-I fibers and coexpressed with presumably -IIa isoform, in Type-IIC fibers. Surprisingly, two antibodies specific to rat MHC-IIa stained those fast fibers, that were histochemically and immunohistochemically classified as Type IIX. This assumption was additionally confirmed by complete absence of fiber staining with antibody specific to rat MHC-IIb and all fast fiber staining with antibody that according to our experience recognizes MHC-IIa and -IIx of rat. Furthermore, quite high-oxidative capacity of all fast fiber types and their weak glycolytic capacity also imply for MHC-IIa and -IIx isoform expression in fast fibers of bear. However, in adult, full-grown animal, only MHC-I and MHC-IIa isoforms were expressed. The expression of only two fast isoforms in bear, like in many other large mammals (humans, cat, dog, goat, cattle, and horse) obviously meets the weight-bearing and locomotor demands of these mammals.
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Affiliation(s)
- Vika Smerdu
- Institute of Anatomy, Medical Faculty, Korytkova 2, 1000 Ljubljana, Slovenia
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Kohn TA, Hoffman LC, Myburgh KH. Identification of myosin heavy chain isoforms in skeletal muscle of four Southern African wild ruminants. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:399-407. [PMID: 17631404 DOI: 10.1016/j.cbpa.2007.05.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 05/26/2007] [Accepted: 05/29/2007] [Indexed: 11/28/2022]
Abstract
The aim was to separate and characterize the myosin heavy chain (MHC) isoforms of four southern African wild ruminants, namely Blesbuck (Damaliscus dorcas phillipsi), Kudu (Tragelaphus strepsiceros), Black Wildebeest (Connochaetes gnou) and Blue Wildebeest (Connochaetes taurinus). Longissimus dorsi muscle samples were subjected to SDS-PAGE and Western blot analyses using antibodies raised against MHC isoforms. The specificity of these antibodies was assessed using immunohistochemistry combined with ATPase histochemistry, Three MHC isoforms were separated and the bands were identified from fastest to slowest migrating as MHC I, MHC IIx and MHC IIa. The mobility of the MHC isoforms was similar for all four species, including that of bovine, but differed from human muscle. Kudu muscle exhibited the lowest proportion of MHC I and the highest proportion of MHC IIx, whereas Blesbuck muscle had the least MHC IIx. The two Wildebeest species were intermediate in isoform content. In conclusion, when new species are studied, existing electrophoretic protocols may need to be modified to achieve quantifiable separation and isoform migration pattern must be verified in order to reach correct interpretations. Furthermore, antibody specificity may differ between techniques as well as species and needs confirmation.
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Affiliation(s)
- Tertius A Kohn
- Department of Physiological Sciences, University of Stellenbosch, Private Bag X1, Matieland, 7602, South Africa
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Toniolo L, Maccatrozzo L, Patruno M, Pavan E, Caliaro F, Rossi R, Rinaldi C, Canepari M, Reggiani C, Mascarello F. Fiber types in canine muscles: myosin isoform expression and functional characterization. Am J Physiol Cell Physiol 2007; 292:C1915-26. [PMID: 17251320 DOI: 10.1152/ajpcell.00601.2006] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study was aimed to achieve a definitive and unambiguous identification of fiber types in canine skeletal muscles and of myosin isoforms that are expressed therein. Correspondence of canine myosin isoforms with orthologs in other species as assessed by base sequence comparison was the basis for primer preparation and for expression analysis with RT-PCR. Expression was confirmed at protein level with histochemistry, immunohistochemistry, and SDS-PAGE combined together and showed that limb and trunk muscles of the dog express myosin heavy chain (MHC) type 1, 2A, and 2X isoforms and the so-called “type 2dog” fibers express the MHC-2X isoform. MHC-2A was found to be the most abundant isoform in the trunk and limb muscle. MHC-2X was expressed in most but not all muscles and more frequently in hybrid 2A-2X fibers than in pure 2X fibers. MHC-2B was restricted to specialized extraocular and laryngeal muscles, although 2B mRNA, but not 2B protein, was occasionally detected in the semimembranosus muscle. Isometric tension (Po) and maximum shortening velocity ( Vo) were measured in single fibers classified on the basis of their MHC isoform composition. Purified myosin isoforms were extracted from single muscle fibers and characterized by the speed ( Vf) of actin filament sliding on myosin in an in vitro motility assay. A close proportionality between Vo and Vf indicated that the diversity in Vo was due to the different myosin isoform composition. Vo increased progressively in the order 1/slow < 2A < 2X < 2B, thus confirming the identification of the myosin isoforms and providing their first functional characterization of canine muscle fibers.
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Affiliation(s)
- Luana Toniolo
- Department of Anatomy and Physiology, University of Padova, Via Marzolo 3, 35131 Padova, Italy
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Strbenc M, Smerdu V, Pogacnik A, Fazarinc G. Myosin heavy chain isoform transitions in canine skeletal muscles during postnatal growth. J Anat 2007; 209:149-63. [PMID: 16879596 PMCID: PMC2100321 DOI: 10.1111/j.1469-7580.2006.00599.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
To gain a better understanding of the normal characteristics of developing canine muscles, myosin heavy chain (MHC) isoform expression was analysed in the axial and limb skeletal muscles of 18 young dogs whose ages ranged from the late prenatal stage to 6 months. We compared the results of immunohistochemistry using ten monoclonal antibodies, specific to different MHC isoforms, and enzyme-histochemical reactions, which demonstrate the activity of myofibrillar ATPase, succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (alpha-GPDH). In the skeletal muscles of fetuses and neonatal dogs the developmental isoforms MHC-emb and MHC-neo were prevalent. In all muscles the primary fibres, located centrally in each muscle fascicle, strongly expressed the slow isoform MHC-I. The adult fast isoform MHC-IIa was first noted in some of the secondary fibres on fetal day 55. During the first 10 days after birth, the expression of MHC-emb declined, as did that of MHC-neo during the second and third weeks. Correspondingly, the expression of MHC-IIa, and later, of MHC-I increased in the secondary fibres. Between the sixth week and second month the expression of MHC-IIx became prominent. The slow rhomboideus muscle exhibited an early expression of the slow isoform in the secondary fibres. Our results indicate that the timing of muscle maturation depends on its activity immediately following birth. The fastest developing muscle was the diaphragm, followed by the fast muscles. A pronounced changeover from developmental to adult isoforms was noted at 4-6 weeks of age, which coincides with the increased physical activity of puppies.
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MESH Headings
- Adenosine Triphosphatases/metabolism
- Animals
- Animals, Newborn
- Dogs
- Glycerolphosphate Dehydrogenase/metabolism
- Muscle Fibers, Fast-Twitch/cytology
- Muscle Fibers, Fast-Twitch/enzymology
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/enzymology
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/growth & development
- Muscle, Skeletal/metabolism
- Myosin Heavy Chains/metabolism
- Protein Isoforms
- Succinate Dehydrogenase/metabolism
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Affiliation(s)
- Malan Strbenc
- Institute of Anatomy, Histology and Embryology, Veterinary Faculty, University of Ljubljana, Slovenia
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