1
|
Roberts MD, McCarthy JJ, Hornberger TA, Phillips SM, Mackey AL, Nader GA, Boppart MD, Kavazis AN, Reidy PT, Ogasawara R, Libardi CA, Ugrinowitsch C, Booth FW, Esser KA. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions. Physiol Rev 2023; 103:2679-2757. [PMID: 37382939 PMCID: PMC10625844 DOI: 10.1152/physrev.00039.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 06/12/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.
Collapse
Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Abigail L Mackey
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital-Bispebjerg and Frederiksberg, and Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Gustavo A Nader
- Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Marni D Boppart
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Paul T Reidy
- Department of Kinesiology, Nutrition and Health, Miami University, Oxford, Ohio, United States
| | - Riki Ogasawara
- Healthy Food Science Research Group, Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Cleiton A Libardi
- MUSCULAB-Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, United States
| | - Karyn A Esser
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, Florida, United States
| |
Collapse
|
2
|
Noonan AM, Oxland TR, Brown SHM. Investigating the active contractile function of the rat paraspinal muscles reveals unique cross-bridge kinetics in the multifidus. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2022; 31:783-791. [PMID: 35089421 DOI: 10.1007/s00586-022-07120-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 11/17/2021] [Accepted: 01/13/2022] [Indexed: 11/24/2022]
Abstract
PURPOSE Various aspects of paraspinal muscle anatomy, biology, and histology have been studied; however, information on paraspinal muscle contractile function is almost nonexistent, thus hindering functional interpretation of these muscles in healthy individuals and those with low back disorders. The aim of this study was to measure and compare the contractile function and force-sarcomere length properties of muscle fibers from the multifidus (MULT) and erector spinae (ES) as well as a commonly studied lower limb muscle (Extensor digitorum longus (EDL)) in the rat. METHODS Single muscle fibers (n = 77 total from 6 animals) were isolated from each of the muscles and tested to determine their active contractile function; all fibers used in the analyses were type IIB. RESULTS There were no significant differences between muscles for specific force (sFo) (p = 0.11), active modulus (p = 0.63), average optimal sarcomere length (p = 0.27) or unloaded shortening velocity (Vo) (p = 0.69). However, there was a significant difference in the rate of force redevelopment (ktr) between muscles (p = < 0.0001), with MULT being significantly faster than both the EDL (p = < 0.0001) and ES (p = 0.0001) and no difference between the EDL and ES (p = 0.41). CONCLUSIONS This finding suggests that multifidus has faster cross-bridge turnover kinetics when compared to other muscles (ES and EDL) when matched for fiber type. Whether the faster cross-bridge kinetics translate to a functionally significant difference in whole muscle performance needs to be studied further.
Collapse
Affiliation(s)
- Alex M Noonan
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Thomas R Oxland
- Department of Orthopaedics, The University of British Columbia, Vancouver, Canada
- International Collaboration on Repair Discoveries (ICORD), The University of British Columbia, Vancouver, Canada
- Department of Mechanical Engineering, The University of British Columbia, Vancouver, Canada
| | - Stephen H M Brown
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
| |
Collapse
|
3
|
Pereyra AS, Lin CT, Sanchez DM, Laskin J, Spangenburg EE, Neufer PD, Fisher-Wellman K, Ellis JM. Skeletal muscle undergoes fiber type metabolic switch without myosin heavy chain switch in response to defective fatty acid oxidation. Mol Metab 2022; 59:101456. [PMID: 35150906 PMCID: PMC8898976 DOI: 10.1016/j.molmet.2022.101456] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/27/2022] [Accepted: 02/03/2022] [Indexed: 11/20/2022] Open
Abstract
Objective Skeletal muscle is a heterogeneous and dynamic tissue that adapts to functional demands and substrate availability by modulating muscle fiber size and type. The concept of muscle fiber type relates to its contractile (slow or fast) and metabolic (glycolytic or oxidative) properties. Here, we tested whether disruptions in muscle oxidative catabolism are sufficient to prompt parallel adaptations in energetics and contractile protein composition. Methods Mice with defective mitochondrial long-chain fatty acid oxidation (mLCFAO) in the skeletal muscle due to loss of carnitine palmitoyltransferase 2 (Cpt2Sk−/−) were used to model a shift in muscle macronutrient catabolism. Glycolytic and oxidative muscles of Cpt2Sk−/− mice and control littermates were compared for the expression of energy metabolism-related proteins, mitochondrial respiratory capacity, and myosin heavy chain isoform composition. Results Differences in bioenergetics and macronutrient utilization in response to energy demands between control muscles were intrinsic to the mitochondria, allowing for a clear distinction of muscle types. Loss of CPT2 ablated mLCFAO and resulted in mitochondrial biogenesis occurring most predominantly in oxidative muscle fibers. The metabolism-related proteomic signature of Cpt2Sk−/− oxidative muscle more closely resembled that of glycolytic muscle than of control oxidative muscle. Respectively, intrinsic substrate-supported mitochondrial respiration of CPT2 deficient oxidative muscles shifted to closely match that of glycolytic muscles. Despite this shift in mitochondrial metabolism, CPT2 deletion did not result in contractile-based fiber type switching according to myosin heavy chain composition analysis. Conclusion The loss of mitochondrial long-chain fatty acid oxidation elicits an adaptive response involving conversion of oxidative muscle toward a metabolic profile that resembles a glycolytic muscle, but this is not accompanied by changes in myosin heavy chain isoforms. These data suggest that shifts in muscle catabolism are not sufficient to drive shifts in the contractile apparatus but are sufficient to drive adaptive changes in metabolic properties. Fuel oxidation in glycolytic compared to oxidative muscles are different and intrinsic to the mitochondria. Muscle CPT2 loss elicits fiber-type dependent mitochondrial biogenesis. Muscle CPT2 loss elicits an oxidative-to-glycolytic shift in mitochondrial and metabolic properties. Muscle CPT2 loss does not alter myosin heavy chain isoform composition. CPT2 deficient muscles demonstrate a metabolic-contractile apparatus mismatch.
Collapse
Affiliation(s)
- Andrea S Pereyra
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA.
| | - Chien-Te Lin
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | | | - Julia Laskin
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Espen E Spangenburg
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | - P Darrell Neufer
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | - Kelsey Fisher-Wellman
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | - Jessica M Ellis
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA.
| |
Collapse
|
4
|
Bączyk M, Manuel M, Roselli F, Zytnicki D. Diversity of Mammalian Motoneurons and Motor Units. ADVANCES IN NEUROBIOLOGY 2022; 28:131-150. [PMID: 36066824 DOI: 10.1007/978-3-031-07167-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although they share the common function of controlling muscle fiber contraction, spinal motoneurons display a remarkable diversity. Alpha-motoneurons are the "final common pathway", which relay all the information from spinal and supraspinal centers and allow the organism to interact with the outside world by controlling the contraction of muscle fibers in the muscles. On the other hand, gamma-motoneurons are specialized motoneurons that do not generate force and instead specifically innervate muscle fibers inside muscle spindles, which are proprioceptive organs embedded in the muscles. Beta-motoneurons are hybrid motoneurons that innervate both extrafusal and intrafusal muscle fibers. Even among alpha-motoneurons, there exists an exquisite diversity in terms of motoneuron electrical and molecular properties, physiological and structural properties of their neuromuscular junctions, and molecular and contractile properties of the innervated muscle fibers. This diversity, across species, across muscles, and across muscle fibers in a given muscle, underlie the vast repertoire of movements that one individual can perform.
Collapse
Affiliation(s)
- Marcin Bączyk
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
| | - Marin Manuel
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, Paris, France.
| | - Francesco Roselli
- Department of Neurology, Ulm University, Ulm, Germany
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE)-Ulm, Ulm, Germany
- Neurozentrum Ulm, Ulm, Germany
| | - Daniel Zytnicki
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, Paris, France
| |
Collapse
|
5
|
Murgia M, Nogara L, Baraldo M, Reggiani C, Mann M, Schiaffino S. Protein profile of fiber types in human skeletal muscle: a single-fiber proteomics study. Skelet Muscle 2021; 11:24. [PMID: 34727990 PMCID: PMC8561870 DOI: 10.1186/s13395-021-00279-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/19/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Human skeletal muscle is composed of three major fiber types, referred to as type 1, 2A, and 2X fibers. This heterogeneous cellular composition complicates the interpretation of studies based on whole skeletal muscle lysate. A single-fiber proteomics approach is required to obtain a fiber-type resolved quantitative information on skeletal muscle pathophysiology. METHODS Single fibers were dissected from vastus lateralis muscle biopsies of young adult males and processed for mass spectrometry-based single-fiber proteomics. We provide and analyze a resource dataset based on relatively pure fibers, containing at least 80% of either MYH7 (marker of slow type 1 fibers), MYH2 (marker of fast 2A fibers), or MYH1 (marker of fast 2X fibers). RESULTS In a dataset of more than 3800 proteins detected by single-fiber proteomics, we selected 404 proteins showing a statistically significant difference among fiber types. We identified numerous type 1 or 2X fiber type-specific protein markers, defined as proteins present at 3-fold or higher levels in these compared to other fiber types. In contrast, we could detect only two 2A-specific protein markers in addition to MYH2. We observed three other major patterns: proteins showing a differential distribution according to the sequence 1 > 2A > 2X or 2X > 2A > 1 and type 2-specific proteins expressed in 2A and 2X fibers at levels 3 times greater than in type 1 fibers. In addition to precisely quantifying known fiber type-specific protein patterns, our study revealed several novel features of fiber type specificity, including the selective enrichment of components of the dystrophin and integrin complexes, as well as microtubular proteins, in type 2X fibers. The fiber type-specific distribution of some selected proteins revealed by proteomics was validated by immunofluorescence analyses with specific antibodies. CONCLUSION We here show that numerous muscle proteins, including proteins whose function is unknown, are selectively enriched in specific fiber types, pointing to potential implications in muscle pathophysiology. This reinforces the notion that single-fiber proteomics, together with recently developed approaches to single-cell proteomics, will be instrumental to explore and quantify muscle cell heterogeneity.
Collapse
Affiliation(s)
- Marta Murgia
- Department of Biomedical Science, University of Padova, 35121, Padova, Italy.
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany.
| | - Leonardo Nogara
- Department of Biomedical Science, University of Padova, 35121, Padova, Italy
- Venetian Institute of Molecular Medicine (VIMM), 35121, Padova, Italy
| | - Martina Baraldo
- Department of Biomedical Science, University of Padova, 35121, Padova, Italy
- Venetian Institute of Molecular Medicine (VIMM), 35121, Padova, Italy
| | - Carlo Reggiani
- Department of Biomedical Science, University of Padova, 35121, Padova, Italy
- Science and Research Center Koper, Institute for Kinesiology Research, 6000, Koper, Slovenia
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
- NNF Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | | |
Collapse
|
6
|
Su Y, Claflin DR, Huang M, Davis CS, Macpherson PCD, Richardson A, Van Remmen H, Brooks SV. Deletion of Neuronal CuZnSOD Accelerates Age-Associated Muscle Mitochondria and Calcium Handling Dysfunction That Is Independent of Denervation and Precedes Sarcopenia. Int J Mol Sci 2021; 22:ijms221910735. [PMID: 34639076 PMCID: PMC8509582 DOI: 10.3390/ijms221910735] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/23/2021] [Accepted: 09/29/2021] [Indexed: 12/17/2022] Open
Abstract
Skeletal muscle suffers atrophy and weakness with aging. Denervation, oxidative stress, and mitochondrial dysfunction are all proposed as contributors to age-associated muscle loss, but connections between these factors have not been established. We examined contractility, mitochondrial function, and intracellular calcium transients (ICTs) in muscles of mice throughout the life span to define their sequential relationships. We performed these same measures and analyzed neuromuscular junction (NMJ) morphology in mice with postnatal deletion of neuronal Sod1 (i-mn-Sod1-/- mice), previously shown to display accelerated age-associated muscle loss and exacerbation of denervation in old age, to test relationships between neuronal redox homeostasis, NMJ degeneration and mitochondrial function. In control mice, the amount and rate of the decrease in mitochondrial NADH during contraction was greater in middle than young age although force was not reduced, suggesting decreased efficiency of NADH utilization prior to the onset of weakness. Declines in both the peak of the ICT and force were observed in old age. Muscles of i-mn-Sod1-/- mice showed degeneration of mitochondrial and calcium handling functions in middle-age and a decline in force generation to a level not different from the old control mice, with maintenance of NMJ morphology. Together, the findings support the conclusion that muscle mitochondrial function decreases during aging and in response to altered neuronal redox status prior to NMJ deterioration or loss of mass and force suggesting mitochondrial defects contribute to sarcopenia independent of denervation.
Collapse
Affiliation(s)
- Yu Su
- Department of Neurosurgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dennis R Claflin
- Department of Surgery, Section of Plastic Surgery, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Meixiang Huang
- Department of Neurology, Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Carol S Davis
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter C D Macpherson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Arlan Richardson
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- VA Medical Center, Oklahoma City, OK 73104, USA
| | - Holly Van Remmen
- VA Medical Center, Oklahoma City, OK 73104, USA
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
- Department of Physiology, Health Science Center, Oklahoma University, Oklahoma City, OK 73104, USA
| | - Susan V Brooks
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
7
|
Ehara A, Taguchi D, Nakadate K, Ueda S. Attractin deficiency causes metabolic and morphological abnormalities in slow-twitch muscle. Cell Tissue Res 2021; 384:745-756. [PMID: 33660050 DOI: 10.1007/s00441-021-03423-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 01/24/2021] [Indexed: 11/25/2022]
Abstract
Skeletal muscle fibers are classified as slow-twitch and fast-twitch fibers, which have different reactive oxygen species (ROS) metabolism and mitochondrial biogenesis. Recently, Attractin (Atrn), which encodes secreted (sAtrn) and transmembrane (mAtrn)-type proteins, has been shown to be involved in free radical scavenging. Although Atrn has been found in skeletal muscle, little is known about the expression levels and function of Atrn in each muscle fiber type. Therefore, we investigate sAtrn and mAtrn expression levels in the slow-twitch soleus (sol) and fast-twitch extensor digitorum longus (EDL) muscles as well as the morphology and expression levels of antioxidant enzymes and functional mitochondrial markers using Atrn-deficient muscles. Both types of Atrn were expressed in the sol and EDL. mAtrn was mainly expressed in the adult sol, whereas sAtrn expression levels did not differ between muscle types. Moreover, mAtrn in the sol was abundantly localized in the subsarcolemmal area, especially in the myoplasm near mitochondria. Atrn-deficient Zitter rats showed muscle fiber atrophy, myofibril misalignment, mitochondrial swelling and vacuolation in the sol but not EDL. Furthermore, the Atrn-deficient sol exhibited a marked reduction in antioxidant enzyme SOD1, GPx1, catalase and Prx6 and mitochondrial functional protein, UCP2, expression. Even Atrn-deficient EDL showed a significant reduction in Prx3, Prx6, UCP2 and UCP3 expression. These data indicate that Atrn-deficiency disturbs ROS metabolism in skeletal muscles. In particular, mAtrn is involved in metabolism in the slow-twitch sol muscle and mAtrn-deficiency may cause ROS imbalance, resulting in morphological abnormalities in the muscle.
Collapse
Affiliation(s)
- Ayuka Ehara
- Department of Histology and Neurobiology, Dokkyo Medical University School of Medicine, 880 Kita-Kobayashi, Mibu, 321-0293, Tochigi, Japan.
| | - Daisuke Taguchi
- Department of Histology and Neurobiology, Dokkyo Medical University School of Medicine, 880 Kita-Kobayashi, Mibu, 321-0293, Tochigi, Japan
- Department of Judo Therapy, Faculty of Medical Technology, Teikyo University, 1-1 Toyosatodai, Utsunomiya-shi, 320-8551, Tochigi, Japan
| | - Kazuhiko Nakadate
- Department of Basic Science, Educational and Research Center for Pharmacy , Meiji Pharmaceutical University , 2-522-1 Noshio, Kiyose-shi, 204- 8588, Tokyo, Japan
| | - Shuichi Ueda
- Department of Histology and Neurobiology, Dokkyo Medical University School of Medicine, 880 Kita-Kobayashi, Mibu, 321-0293, Tochigi, Japan
| |
Collapse
|
8
|
Roberts MD, Haun CT, Vann CG, Osburn SC, Young KC. Sarcoplasmic Hypertrophy in Skeletal Muscle: A Scientific "Unicorn" or Resistance Training Adaptation? Front Physiol 2020; 11:816. [PMID: 32760293 PMCID: PMC7372125 DOI: 10.3389/fphys.2020.00816] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 06/18/2020] [Indexed: 12/19/2022] Open
Abstract
Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm. Select evidence suggests sarcoplasmic hypertrophy, or a disproportionate expansion of the sarcoplasm relative to myofibril protein accretion, coincides with muscle fiber or tissue growth during resistance training. There is also evidence to support other modes of hypertrophy occur during periods of resistance training including a proportional accretion of myofibril protein with fiber or tissue growth (i.e., conventional hypertrophy), or myofibril protein accretion preceding fiber or tissue growth (i.e., myofibril packing). In this review, we discuss methods that have been used to investigate these modes of hypertrophy. Particular attention is given to sarcoplasmic hypertrophy throughout. Thus, descriptions depicting this process as well as the broader implications of this phenomenon will be posited. Finally, we propose future human and rodent research that can further our understanding in this area of muscle physiology.
Collapse
Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, United States
| | - Cody T Haun
- Fitomics, LLC, Birmingham, AL, United States
| | | | | | - Kaelin C Young
- School of Kinesiology, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, United States
| |
Collapse
|
9
|
Gundelach LA, Hüser MA, Beutner D, Ruther P, Bruegmann T. Towards the clinical translation of optogenetic skeletal muscle stimulation. Pflugers Arch 2020; 472:527-545. [PMID: 32415463 PMCID: PMC7239821 DOI: 10.1007/s00424-020-02387-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/05/2020] [Accepted: 04/28/2020] [Indexed: 12/27/2022]
Abstract
Paralysis is a frequent phenomenon in many diseases, and to date, only functional electrical stimulation (FES) mediated via the innervating nerve can be employed to restore skeletal muscle function in patients. Despite recent progress, FES has several technical limitations and significant side effects. Optogenetic stimulation has been proposed as an alternative, as it may circumvent some of the disadvantages of FES enabling cell type–specific, spatially and temporally precise stimulation of cells expressing light-gated ion channels, commonly Channelrhodopsin2. Two distinct approaches for the restoration of skeletal muscle function with optogenetics have been demonstrated: indirect optogenetic stimulation through the innervating nerve similar to FES and direct optogenetic stimulation of the skeletal muscle. Although both approaches show great promise, both have their limitations and there are several general hurdles that need to be overcome for their translation into clinics. These include successful gene transfer, sustained optogenetic protein expression, and the creation of optically active implantable devices. Herein, a comprehensive summary of the underlying mechanisms of electrical and optogenetic approaches is provided. With this knowledge in mind, we substantiate a detailed discussion of the advantages and limitations of each method. Furthermore, the obstacles in the way of clinical translation of optogenetic stimulation are discussed, and suggestions on how they could be overcome are provided. Finally, four specific examples of pathologies demanding novel therapeutic measures are discussed with a focus on the likelihood of direct versus indirect optogenetic stimulation.
Collapse
Affiliation(s)
- Lili A Gundelach
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany
| | - Marc A Hüser
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center, Göttingen, Germany
| | - Dirk Beutner
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center, Göttingen, Germany
| | - Patrick Ruther
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
- BrainLinks-BrainTools Cluster of Excellence at the University of Freiburg, Freiburg, Germany
| | - Tobias Bruegmann
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany.
- DZHK e.V. (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.
| |
Collapse
|
10
|
Chemello F, Grespi F, Zulian A, Cancellara P, Hebert-Chatelain E, Martini P, Bean C, Alessio E, Buson L, Bazzega M, Armani A, Sandri M, Ferrazza R, Laveder P, Guella G, Reggiani C, Romualdi C, Bernardi P, Scorrano L, Cagnin S, Lanfranchi G. Transcriptomic Analysis of Single Isolated Myofibers Identifies miR-27a-3p and miR-142-3p as Regulators of Metabolism in Skeletal Muscle. Cell Rep 2020; 26:3784-3797.e8. [PMID: 30917329 DOI: 10.1016/j.celrep.2019.02.105] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 06/29/2018] [Accepted: 02/26/2019] [Indexed: 12/27/2022] Open
Abstract
Skeletal muscle is composed of different myofiber types that preferentially use glucose or lipids for ATP production. How fuel preference is regulated in these post-mitotic cells is largely unknown, making this issue a key question in the fields of muscle and whole-body metabolism. Here, we show that microRNAs (miRNAs) play a role in defining myofiber metabolic profiles. mRNA and miRNA signatures of all myofiber types obtained at the single-cell level unveiled fiber-specific regulatory networks and identified two master miRNAs that coordinately control myofiber fuel preference and mitochondrial morphology. Our work provides a complete and integrated mouse myofiber type-specific catalog of gene and miRNA expression and establishes miR-27a-3p and miR-142-3p as regulators of lipid use in skeletal muscle.
Collapse
Affiliation(s)
- Francesco Chemello
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CRIBI Biotechnology Centre, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Francesca Grespi
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; Venetian Institute of Molecular Medicine, Via Orus 2, 35131 Padova, Italy
| | - Alessandra Zulian
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Pasqua Cancellara
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Etienne Hebert-Chatelain
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; Venetian Institute of Molecular Medicine, Via Orus 2, 35131 Padova, Italy
| | - Paolo Martini
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Camilla Bean
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; Venetian Institute of Molecular Medicine, Via Orus 2, 35131 Padova, Italy
| | - Enrico Alessio
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CRIBI Biotechnology Centre, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Lisa Buson
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Martina Bazzega
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Andrea Armani
- Venetian Institute of Molecular Medicine, Via Orus 2, 35131 Padova, Italy
| | - Marco Sandri
- Venetian Institute of Molecular Medicine, Via Orus 2, 35131 Padova, Italy; Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CIR-Myo Myology Center, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Ruggero Ferrazza
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo (Trento), Italy
| | - Paolo Laveder
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Graziano Guella
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo (Trento), Italy
| | - Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Chiara Romualdi
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Paolo Bernardi
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy
| | - Luca Scorrano
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; Venetian Institute of Molecular Medicine, Via Orus 2, 35131 Padova, Italy
| | - Stefano Cagnin
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CRIBI Biotechnology Centre, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CIR-Myo Myology Center, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy.
| | - Gerolamo Lanfranchi
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CRIBI Biotechnology Centre, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy; CIR-Myo Myology Center, University of Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy.
| |
Collapse
|
11
|
Zarzissi S, Zghal F, Bouzid MA, Hureau TJ, Sahli S, Ben Hassen H, Rebai H. Centrally-mediated regulation of peripheral fatigue during knee extensor exercise and consequences on the force-duration relationship in older men. Eur J Sport Sci 2019; 20:641-649. [PMID: 31397211 DOI: 10.1080/17461391.2019.1655099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The aim of the present study was to investigate the existence of a critical threshold beyond which peripheral fatigue would not further decrease during knee extensor (KE) exercise in older men, and the consequences of this mechanism on the force-duration relationship. Twelve old men (59 ± 2 years) randomly performed two different sessions, in which they performed 60 maximum voluntary contractions (MVC; 3s contraction, 2s relaxation). One trial was performed in the unfatigued state (CTRL) and one other following fatiguing neuromuscular electrical stimulation of the KE (FNMES). Peripheral and central fatigue were quantified via pre/post-exercise decreases in quadriceps twitch-force (Δ Ptw) and voluntary activation (ΔVA). Critical torque (CT) was determined as the mean force of the last 12 contractions while W' was calculated as the area above CT. Compared with CTRL, pre-fatigue (Δ Ptw = -10.3 ± 6.2%) resulted in a significant (p < 0.05) reduction in W' (-18.2 ± 1.6%) in FNMES. However, CT (∼964 N), ΔVA (∼15%) and Δ Ptw (∼25%) post-MVCs were similar between both conditions. In CTRL, W' was correlated with Δ Ptw (r 2 = 0.78). Moreover, the difference in W' between CTRL and FNMES was correlated with the level of pre-fatigue induced in FNMES (r 2 = 0.76). These findings document that peripheral fatigue is confined to an individual threshold during KE exercise in older men. Furthermore, correlative results suggest that mechanisms regulating peripheral fatigue to a critical threshold also restrict W', and therefore play a role in exercise capacity in older men.
Collapse
Affiliation(s)
- Slim Zarzissi
- Research Unit: Education, Motor Skills, Sport and Health (EM2S), UR15JS01, High institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Firas Zghal
- Research Unit: Education, Motor Skills, Sport and Health (EM2S), UR15JS01, High institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia.,Faculté des Sciences du Sport, Université Côte d'Azur, LAMHESS, Nice, France
| | - Mohamed Amine Bouzid
- Research Unit: Education, Motor Skills, Sport and Health (EM2S), UR15JS01, High institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Thomas J Hureau
- Mitochondria, oxidative stress and muscular protection laboratory (EA 3072), Faculty of Medicine, University of Strasbourg, Strasbourg, France
| | - Sonia Sahli
- Research Unit: Education, Motor Skills, Sport and Health (EM2S), UR15JS01, High institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Habib Ben Hassen
- Research Unit: Education, Motor Skills, Sport and Health (EM2S), UR15JS01, High institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Haithem Rebai
- Research Unit: Education, Motor Skills, Sport and Health (EM2S), UR15JS01, High institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| |
Collapse
|
12
|
Anderson LB, Latour CD, Khader O, Massey BH, Cobb B, Pond AL. Ether-a-go-go related gene-1a potassium channel abundance varies within specific skeletal muscle fiber type. Eur J Transl Myol 2019; 29:8402. [PMID: 31579487 PMCID: PMC6767934 DOI: 10.4081/ejtm.2019.8402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 08/28/2019] [Indexed: 01/24/2023] Open
Abstract
The ERG1A K+ channel, which is partially responsible for repolarization of the cardiac action potential, has also been reported in skeletal muscle where it modulates ubiquitin proteolysis. Because ERG1A protein appears variably expressed in muscles composed of mixed fiber types, we hypothesized that its abundance in skeletal muscle might differ with fiber type. Indeed, skeletal muscle fibers vary in speed of contraction (fast or slow), which is mainly determined by myosin heavy chain (MyHC) isoform content, but a sarcolemmal K+ channel might also modulate contraction speed. To test our hypothesis, we cryo-sectioned Soleus (SOL), Extensor Digitorum Longus (EDL), and Gastrocnemius muscles from five rats. These muscles were chosen because the SOL and EDL contain an abundance of slow- and fast-twitch fibers, respectively, while the Gastrocnemius has a more heterogeneous composition. The muscle sections were co-immunostained for the ERG1A protein and either the fast- or slow-twitch MyHC to identify fiber type. ERG1A fluorescence was then measured in the sarcolemma of each fiber type and compared. The data reveal that the ERG1A protein is more abundant in the fibers of the SOL than in the EDL muscles, suggesting ERG1A may be more abundant in the slow than the fast fibers, and this was confirmed with immunoblot. However, because of the homogeneity of fiber type within these muscles, it was not possible to get enough data from both fiber types within a single muscle to compare ERG1A composition within fiber type. However, immunohistochemistry of sections from the fiber type heterogeneous Gastrocnemius muscle reveals that slow fibers had, on average, a 17.2% greater ERG1A fluorescence intensity than fast fibers (p<0.03). Further, immunoblot reveals that ERG1A protein is 41.6% more abundant (p=0.051) in old than in young rat Gastrocnemius muscle. We postulate that this membrane bound voltage-gated channel may affect membrane characteristics, the duration of the action potential generated, and/or the speed of contraction. Indeed, ERG1A protein is more abundant in aged and atrophic skeletal muscle, both of which exhibit slower rates of contraction.
Collapse
Affiliation(s)
- Luke B Anderson
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL
| | - Chase D Latour
- Department of Psychiatry, Washington University in St. Louis, St. Louis, MO
| | - Omar Khader
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL
| | | | - Brittan Cobb
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL
| | - Amber L Pond
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL
| |
Collapse
|
13
|
Hemingway HW, Burrows AM, Omstead KM, Zohdy S, Pastor JF, Muchlinski MN. Vertical Clinging and Leaping Ahead: How Bamboo Has Shaped the Anatomy and Physiology of Hapalemur. Anat Rec (Hoboken) 2019; 303:295-307. [PMID: 31148418 DOI: 10.1002/ar.24183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 11/29/2018] [Accepted: 02/01/2019] [Indexed: 11/10/2022]
Abstract
Hapalemur sps. and Prolemur simus (bamboo lemurs, collectively) stand out from the relatively homogeneous lemurids because they are bamboo feeders and vertical clingers and leapers. This unique diet presents equally unique challenges, like its verticality, toughness, and toxicity. The bamboo lemurs share the generalized anatomy of the other lemurids, but also display some well-documented skeletal adaptations, perhaps to overcome the problems presented by their specialization. Soft-tissue adaptations, however, remain largely unexplored. Explored here are possible soft-tissue adaptations in Hapalemur griseus. We compare H. griseus with other lemurids, Propithecus, Galago, Tarsier, and a tree shrew. Based on the available anatomical and physiological data, we hypothesize that Hapalemur and Prolemur species will have differences in hindlimb morphology when compared with other lemurids. We predict that H. griseus will have more hindlimb muscle mass and will amplify muscle mass differences with increased type II muscle fibers. Relative hindlimb muscle mass in H. griseus is less than other prosimians sampled, yet relative sural muscle mass is significantly heavier (P < 0.01) in H. griseus. Results show that the soleus muscle of H. griseus has a higher amount of type II (fast) fibers in plantarflexors. These findings indicate although H. griseus shares some generalized lemurid morphology, its diet of bamboo may have pushed this generalized lemurid to an anatomical extreme. We suspect additional bamboo-specific adaptations in their anatomy and physiology will be uncovered with further examination into the anatomy of the bamboo lemurs. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc. Anat Rec, 303:295-307, 2020. © 2019 American Association for Anatomy.
Collapse
Affiliation(s)
- Holden W Hemingway
- Center for Anatomical Sciences, University of North Texas Health Science Center, Fort Worth, Texas.,Department of Neuroscience, University of Kentucky, Lexington, Kentucky
| | - Anne M Burrows
- Department of Physical Therapy, Duquesne University, Pittsburgh, Pennsylvania
| | - Kailey M Omstead
- Department of Physical Therapy, Duquesne University, Pittsburgh, Pennsylvania
| | - Sarah Zohdy
- School of Forestry and Wildlife Sciences and College of Veterinary Medicine, Auburn University, Auburn, Alabama
| | | | - Magdalena N Muchlinski
- Center for Anatomical Sciences, University of North Texas Health Science Center, Fort Worth, Texas
| |
Collapse
|
14
|
Schiaffino S. Muscle fiber type diversity revealed by anti-myosin heavy chain antibodies. FEBS J 2018; 285:3688-3694. [PMID: 29761627 DOI: 10.1111/febs.14502] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 04/24/2018] [Accepted: 05/08/2018] [Indexed: 01/02/2023]
Abstract
Different forms of myosin heavy chains (MyHCs), coded by a large family of sarcomeric MYH genes, are expressed in striated muscles. The generation of specific anti-MyHC antibodies has provided a powerful tool to define the fiber types present in skeletal muscles, their functional properties, their response to conditions that affect muscle plasticity and their changes in muscle disorders. Cardiomyocyte heterogeneity has been revealed by the serendipitous observation that different MyHCs are present in atrial and ventricular myocardium and in heart conduction tissue. Developmental MyHCs present in embryonic and fetal/neonatal skeletal muscle are re-expressed during muscle regeneration and can be used to identify regenerating fibers in muscle diseases. MyHC isoforms provide cell type-specific markers to identify the signaling pathways that control muscle cell identity and are an essential reference to interpret the results of single-cell transcriptomics and proteomics.
Collapse
|
15
|
Bloise FF, Cordeiro A, Ortiga-Carvalho TM. Role of thyroid hormone in skeletal muscle physiology. J Endocrinol 2018; 236:R57-R68. [PMID: 29051191 DOI: 10.1530/joe-16-0611] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/19/2017] [Indexed: 12/31/2022]
Abstract
Thyroid hormones (TH) are crucial for development, growth, differentiation, metabolism and thermogenesis. Skeletal muscle (SM) contractile function, myogenesis and bioenergetic metabolism are influenced by TH. These effects depend on the presence of the TH transporters MCT8 and MCT10 in the plasma membrane, the expression of TH receptors (THRA or THRB) and hormone availability, which is determined either by the activation of thyroxine (T4) into triiodothyronine (T3) by type 2 iodothyronine deiodinases (D2) or by the inactivation of T4 into reverse T3 by deiodinases type 3 (D3). SM relaxation and contraction rates depend on T3 regulation of myosin expression and energy supplied by substrate oxidation in the mitochondria. The balance between D2 and D3 expression determines TH intracellular levels and thus influences the proliferation and differentiation of satellite cells, indicating an important role of TH in muscle repair and myogenesis. During critical illness, changes in TH levels and in THR and deiodinase expression negatively affect SM function and repair. This review will discuss the influence of TH action on SM contraction, bioenergetics metabolism, myogenesis and repair in health and illness conditions.
Collapse
Affiliation(s)
- Flavia F Bloise
- Institute of Biophysics Carlos Chagas FilhoLaboratory of Translational Endocrinology, Rio de Janeiro, Brazil
| | - Aline Cordeiro
- Institute of Biophysics Carlos Chagas FilhoLaboratory of Translational Endocrinology, Rio de Janeiro, Brazil
| | - Tania Maria Ortiga-Carvalho
- Institute of Biophysics Carlos Chagas FilhoLaboratory of Translational Endocrinology, Rio de Janeiro, Brazil
| |
Collapse
|
16
|
Kissane RWP, Egginton S, Askew GN. Regional variation in the mechanical properties and fibre-type composition of the rat extensor digitorum longus muscle. Exp Physiol 2017; 103:111-124. [DOI: 10.1113/ep086483] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 10/23/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Roger W. P. Kissane
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| | - Stuart Egginton
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| | - Graham N. Askew
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| |
Collapse
|
17
|
Vaughan SK, Stanley OL, Valdez G. Impact of Aging on Proprioceptive Sensory Neurons and Intrafusal Muscle Fibers in Mice. J Gerontol A Biol Sci Med Sci 2017; 72:771-779. [PMID: 27688482 DOI: 10.1093/gerona/glw175] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/09/2016] [Indexed: 11/13/2022] Open
Abstract
The impact of aging on proprioceptive sensory neurons and intrafusal muscle fibers (IMFs) remains largely unexplored despite the central function these cells play in modulating voluntary movements. Here, we show that proprioceptive sensory neurons undergo deleterious morphological changes in middle age (11- to 13-month-old) and old (15- to 21-month-old) mice. In the extensor digitorum longus and soleus muscles of middle age and old mice, there is a significant increase in the number of Ia afferents with large swellings that fail to properly wrap around IMFs compared with young adult (2- to 4-month-old) mice. Fewer II afferents were also found in the same muscles of middle age and old mice. Although these age-related changes in peripheral nerve endings were accompanied by degeneration of proprioceptive sensory neuron cell bodies in dorsal root ganglia (DRG), the morphology and number of IMFs remained unchanged. Our analysis also revealed normal levels of neurotrophin 3 (NT3) but dysregulated expression of the tyrosine kinase receptor C (TrkC) in aged muscles and DRGs, respectively. These results show that proprioceptive sensory neurons degenerate prior to atrophy of IMFs during aging, and in the presence of the NT3/TrkC signaling axis.
Collapse
Affiliation(s)
- Sydney K Vaughan
- Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke.,Graduate Program in Translational Biology, Medicine, and Health and
| | - Olivia L Stanley
- Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke
| | - Gregorio Valdez
- Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke.,Department of Biological Sciences, Virginia Tech, Blacksburg
| |
Collapse
|
18
|
Komiya Y, Sawano S, Mashima D, Ichitsubo R, Nakamura M, Tatsumi R, Ikeuchi Y, Mizunoya W. Mouse soleus (slow) muscle shows greater intramyocellular lipid droplet accumulation than EDL (fast) muscle: fiber type-specific analysis. J Muscle Res Cell Motil 2017; 38:163-173. [PMID: 28281032 DOI: 10.1007/s10974-017-9468-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/16/2017] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is the main tissue of lipid metabolism and accordingly is critical for homeostasis and energy production; however, the determinants of lipid accumulation in skeletal muscle are unknown. Here, we examined whether the soleus muscle (predominantly slow-twitch fibers) has a higher lipid accumulation capacity than that of the extensor digitorum longus (EDL, predominantly fast-twitch fibers) muscle in mice. Soleus and EDL muscles were harvested from male C57BL/6J mice. The mRNA levels of genes involved in fatty acid import and triglyceride synthesis and accumulation were examined in soleus and EDL muscles. The intramyocellular lipid (IMCL) droplets of muscle cross sections and isolated single fibers were visualized by staining with BODIPY493/503, and fiber types were determined by immunofluorescent detection of myosin heavy chain (MyHC) isoforms. We detected higher mRNA expression of genes related to lipid accumulation in the soleus than the EDL. We also observed a marked increase of IMCL in single fibers from the soleus, but not the EDL, after treatment with a high-fat diet plus denervation. Interestingly, greater accumulation of IMCL droplets was observed in type 2A and 2X fibers (MyHC2A- and MyHC2X-positive fibers) than type 1 fibers (MyHC1-positive fibers) in soleus muscles. These results suggest that the soleus contains more IMCL owing to the higher population of type 2A fibers, and the difference in lipid accumulation between the soleus and EDL could depend on fiber type composition.
Collapse
Affiliation(s)
- Yusuke Komiya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, 034-8628, Japan
| | - Shoko Sawano
- Department of Food Nutrition, Fukuoka Women's Junior College, Dazaifu, 818-0193, Japan
| | - Daisuke Mashima
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Riho Ichitsubo
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Mako Nakamura
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Ryuichi Tatsumi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Yoshihide Ikeuchi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Wataru Mizunoya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
| |
Collapse
|
19
|
Vanhatalo A, Black MI, DiMenna FJ, Blackwell JR, Schmidt JF, Thompson C, Wylie LJ, Mohr M, Bangsbo J, Krustrup P, Jones AM. The mechanistic bases of the power-time relationship: muscle metabolic responses and relationships to muscle fibre type. J Physiol 2016; 594:4407-23. [PMID: 26940850 DOI: 10.1113/jp271879] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/01/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The power-asymptote (critical power; CP) of the hyperbolic power-time relationship for high-intensity exercise defines a threshold between steady-state and non-steady-state exercise intensities and the curvature constant (W') indicates a fixed capacity for work >CP that is related to a loss of muscular efficiency. The present study reports novel evidence on the muscle metabolic underpinnings of CP and W' during whole-body exercise and their relationships to muscle fibre type. We show that the W' is not correlated with muscle fibre type distribution and that it represents an elevated energy contribution from both oxidative and glycolytic/glycogenolytic metabolism. We show that there is a positive correlation between CP and highly oxidative type I muscle fibres and that muscle metabolic steady-state is attainable <CP but not >CP. Our findings indicate a mechanistic link between the bioenergetic characteristics of muscle fibre types and the power-time relationship for high-intensity exercise. ABSTRACT We hypothesized that: (1) the critical power (CP) will represent a boundary separating steady-state from non-steady-state muscle metabolic responses during whole-body exercise and (2) that the CP and the curvature constant (W') of the power-time relationship for high-intensity exercise will be correlated with type I and type IIx muscle fibre distributions, respectively. Four men and four women performed a 3 min all-out cycling test for the estimation of CP and constant work rate (CWR) tests slightly >CP until exhaustion (Tlim ), slightly <CP for 24 min and until the >CP Tlim isotime to test the first hypothesis. Eleven men performed 3 min all-out tests and donated muscle biopsies to test the second hypothesis. Below CP, muscle [PCr] [42.6 ± 7.1 vs. 49.4 ± 6.9 mmol (kg d.w.)(-1) ], [La(-) ] [34.8 ± 12.6 vs. 35.5 ± 13.2 mmol (kg d.w.)(-1) ] and pH (7.11 ± 0.08 vs. 7.10 ± 0.11) remained stable between ∼12 and 24 min (P > 0.05 for all), whereas these variables changed with time >CP such that they were greater [[La(-) ] 95.6 ± 14.1 mmol (kg d.w.)(-1) ] and lower [[PCr] 24.2 ± 3.9 mmol (kg d.w.)(-1) ; pH 6.84 ± 0.06] (P < 0.05) at Tlim (740 ± 186 s) than during the <CP trial. The CP (234 ± 53 W) was correlated with muscle type I (r = 0.67, P = 0.025) and inversely correlated with muscle type IIx fibre proportion (r = -0.76, P = 0.01). There was no relationship between W' (19.4 ± 6.3 kJ) and muscle fibre type. These data indicate a mechanistic link between the bioenergetic characteristics of different muscle fibre types and the power-duration relationship. The CP reflects the bioenergetic characteristics of highly oxidative type I muscle fibres, such that a muscle metabolic steady-state is attainable below and not above CP.
Collapse
Affiliation(s)
- Anni Vanhatalo
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Matthew I Black
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Fred J DiMenna
- Teachers College, Department of Biobehavioral Sciences, Columbia University, New York, NY, USA
| | - Jamie R Blackwell
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Jakob Friis Schmidt
- Department of Nutrition, Exercise and Sports, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Christopher Thompson
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Lee J Wylie
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Magni Mohr
- Faculty of Natural and Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.,Center of Health and Human Performance, Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Peter Krustrup
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK.,Department of Nutrition, Exercise and Sports, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Andrew M Jones
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| |
Collapse
|
20
|
Sarcoplasmic Reticulum Phospholipid Fatty Acid Composition and Sarcolipin Content in Rat Skeletal Muscle. J Membr Biol 2015; 248:1089-96. [PMID: 26193810 DOI: 10.1007/s00232-015-9822-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 07/14/2015] [Indexed: 10/23/2022]
Abstract
In a previous study, we reported lower sarcoplasmic reticulum (SR) Ca(2+) pump ionophore ratios in rat soleus compared to red and white gastrocnemius (RG, WG) muscles which may be indicative of greater SR Ca(2+) permeability in soleus. Here we assessed the lipid composition of the SR membranes obtained from these muscles to determine if SR docosahexaenoic acid (DHA) content and fatty acid unsaturation could help to explain the previously observed differences in SR Ca(2+) permeability. Since we have shown previously that sarcolipin may also influence SR Ca(2+) permeability, we also examined the levels of sarcolipin in rat muscle. We found that SR membrane DHA content was significantly higher in soleus (5.3 ± 0.2 %) compared to RG (4.2 ± 0.2 %) and WG (3.3 ± 0.2 %). Likewise, total SR membrane unsaturation and unsaturation index (UI) were significantly higher in soleus (% unsaturation: 59.1 ± 2.4; UI: 362.9 ± 0.8) compared to RG (% unsaturation: 55.3 ± 1.0; UI: 320.9 ± 2.5) and WG (% unsaturation: 52.6 ± 1.1; UI: 310. ± 2.2). Sarcolipin protein was 17-fold more abundant in rat soleus compared to RG and was not detected in WG; however, comparisons between soleus, RG, and WG in sarcolipin-null mice revealed that, in the absence of sarcolipin, ionophore ratios are still lowest in soleus and highest in WG. Overall, our results suggest that SR membrane DHA content and unsaturation, and, in part, sarcolipin expression may contribute to SR Ca(2+) permeability and, in turn, may have implications in muscle-based metabolism and diet-induced obesity.
Collapse
|
21
|
Khodabukus A, Baar K. Contractile and metabolic properties of engineered skeletal muscle derived from slow and fast phenotype mouse muscle. J Cell Physiol 2015; 230:1750-7. [PMID: 25335966 DOI: 10.1002/jcp.24848] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 10/14/2014] [Indexed: 11/08/2022]
Abstract
Satellite cells derived from fast and slow muscles have been shown to adopt contractile and metabolic properties of their parent muscle. Mouse muscle shows less distinctive fiber-type profiles than rat or rabbit muscle. Therefore, in this study we sought to determine whether three-dimensional muscle constructs engineered from slow soleus (SOL) and fast tibialis anterior (TA) from mice would adopt the contractile and metabolic properties of their parent muscle. Time-to-peak tension (TPT) and half-relaxation time (1/2RT) was significantly slower in SOL constructs. In agreement with TPT, TA constructs contained significantly higher levels of fast myosin heavy chain (MHC) and fast troponin C, I, and T isoforms. Fast SERCA protein, both slow and fast calsequestrin isoforms and parvalbumin were found at higher levels in TA constructs. SOL constructs were more fatigue resistant and contained higher levels of the mitochondrial proteins SDH and ATP synthase and the fatty acid transporter CPT-1. SOL constructs contained lower levels of the glycolytic enzyme phosphofructokinase but higher levels of the β-oxidation enzymes LCAD and VLCAD suggesting greater fat oxidation. Despite no changes in PGC-1α protein, SOL constructs contained higher levels of SIRT1 and PRC. TA constructs contained higher levels of the slow-fiber program repressor SOX6 and the six transcriptional complex (STC) proteins Eya1 and Six4 which may underlie the higher in fast-fiber and lower slow-fiber program proteins. Overall, we have found that muscles engineered from predominantly slow and fast mouse muscle retain contractile and metabolic properties of their native muscle.
Collapse
Affiliation(s)
- Alastair Khodabukus
- Department of Neurobiology, Physiology and Behavior, University of California Davis, Davis, California
| | | |
Collapse
|
22
|
Alibardi L. Regenerating tail muscles in lizard contain Fast but not Slow Myosin indicating that most myofibers belong to the fast twitch type for rapid contraction. Tissue Cell 2015; 47:533-40. [PMID: 26164738 DOI: 10.1016/j.tice.2015.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/02/2015] [Accepted: 06/11/2015] [Indexed: 11/16/2022]
Abstract
During tail regeneration in lizards a large mass of muscle tissue is formed in form of segmental myomeres of similar size located under the dermis of the new tail. These muscles accumulate glycogen and a fast form of myosin typical for twitch myofibers as it is shown by light and ultrastructural immunocytochemistry using an antibody directed against a Fast Myosin Heavy Chain. High resolution immunogold labeling shows that an intense labeling for fast myosin is localized over the thick filaments of the numerous myofibrils in about 70% of the regenerated myofibers while the labeling becomes less intense in the remaining muscle fibers. The present observations indicate that at least two subtypes of Fast Myosin containing muscle fibers are regenerated, the prevalent type was of the fast twitch containing few mitochondria, sparse glycogen, numerous smooth endoplasmic reticulum vesicles. The second, and less frequent type was a Fast-Oxidative-Glycolitic twitch fiber containing more mitochondria, a denser cytoplasm and myofibrils. Since their initial differentiation, myoblasts, myotubes and especially the regenerated myofibers do not accumulate any immuno-detectable Slow Myosin Heavy Chain. The study indicates that most of the segmental muscles of the regenerated tail serve for the limited bending of the tail during locomotion and trashing after amputation of the regenerated tail, a phenomenon that facilitates predator escape.
Collapse
Affiliation(s)
- L Alibardi
- Comparative Histolab and Department of Bigea, University of Bologna, via Selmi 3, 40126, Bologna, Italy.
| |
Collapse
|
23
|
Murgia M, Nagaraj N, Deshmukh AS, Zeiler M, Cancellara P, Moretti I, Reggiani C, Schiaffino S, Mann M. Single muscle fiber proteomics reveals unexpected mitochondrial specialization. EMBO Rep 2015; 16:387-95. [PMID: 25643707 PMCID: PMC4364878 DOI: 10.15252/embr.201439757] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mammalian skeletal muscles are composed of multinucleated cells termed slow or fast fibers according to their contractile and metabolic properties. Here, we developed a high-sensitivity workflow to characterize the proteome of single fibers. Analysis of segments of the same fiber by traditional and unbiased proteomics methods yielded the same subtype assignment. We discovered novel subtype-specific features, most prominently mitochondrial specialization of fiber types in substrate utilization. The fiber type-resolved proteomes can be applied to a variety of physiological and pathological conditions and illustrate the utility of single cell type analysis for dissecting proteomic heterogeneity.
Collapse
Affiliation(s)
- Marta Murgia
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Nagarjuna Nagaraj
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Atul S Deshmukh
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marlis Zeiler
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Pasqua Cancellara
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Irene Moretti
- Venetian Institute of Molecular Medicine, Padua, Italy
| | - Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | | | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
24
|
Goncalves RLS, Quinlan CL, Perevoshchikova IV, Hey-Mogensen M, Brand MD. Sites of superoxide and hydrogen peroxide production by muscle mitochondria assessed ex vivo under conditions mimicking rest and exercise. J Biol Chem 2014; 290:209-27. [PMID: 25389297 DOI: 10.1074/jbc.m114.619072] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The sites and rates of mitochondrial production of superoxide and H2O2 in vivo are not yet defined. At least 10 different mitochondrial sites can generate these species. Each site has a different maximum capacity (e.g. the outer quinol site in complex III (site IIIQo) has a very high capacity in rat skeletal muscle mitochondria, whereas the flavin site in complex I (site IF) has a very low capacity). The maximum capacities can greatly exceed the actual rates observed in the absence of electron transport chain inhibitors, so maximum capacities are a poor guide to actual rates. Here, we use new approaches to measure the rates at which different mitochondrial sites produce superoxide/H2O2 using isolated muscle mitochondria incubated in media mimicking the cytoplasmic substrate and effector mix of skeletal muscle during rest and exercise. We find that four or five sites dominate during rest in this ex vivo system. Remarkably, the quinol site in complex I (site IQ) and the flavin site in complex II (site IIF) each account for about a quarter of the total measured rate of H2O2 production. Site IF, site IIIQo, and perhaps site EF in the β-oxidation pathway account for most of the remainder. Under conditions mimicking mild and intense aerobic exercise, total production is much less, and the low capacity site IF dominates. These results give novel insights into which mitochondrial sites may produce superoxide/H2O2 in vivo.
Collapse
Affiliation(s)
| | - Casey L Quinlan
- From the Buck Institute for Research on Aging, Novato, California 94945
| | | | | | - Martin D Brand
- From the Buck Institute for Research on Aging, Novato, California 94945
| |
Collapse
|
25
|
Oas ST, Bryantsev AL, Cripps RM. Arrest is a regulator of fiber-specific alternative splicing in the indirect flight muscles of Drosophila. ACTA ACUST UNITED AC 2014; 206:895-908. [PMID: 25246617 PMCID: PMC4178973 DOI: 10.1083/jcb.201405058] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The RNA-binding protein Arrest occupies a novel intranuclear domain and directs flight muscle–specific patterns of alternative splicing in flies. Drosophila melanogaster flight muscles are distinct from other skeletal muscles, such as jump muscles, and express several uniquely spliced muscle-associated transcripts. We sought to identify factors mediating splicing differences between the flight and jump muscle fiber types. We found that the ribonucleic acid–binding protein Arrest (Aret) is expressed in flight muscles: in founder cells, Aret accumulates in a novel intranuclear compartment that we termed the Bruno body, and after the onset of muscle differentiation, Aret disperses in the nucleus. Down-regulation of the aret gene led to ultrastructural changes and functional impairment of flight muscles, and transcripts of structural genes expressed in the flight muscles became spliced in a manner characteristic of jump muscles. Aret also potently promoted flight muscle splicing patterns when ectopically expressed in jump muscles or tissue culture cells. Genetically, aret is located downstream of exd (extradenticle), hth (homothorax), and salm (spalt major), transcription factors that control fiber identity. Our observations provide insight into a transcriptional and splicing regulatory network for muscle fiber specification.
Collapse
Affiliation(s)
- Sandy T Oas
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
| | - Anton L Bryantsev
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
| | - Richard M Cripps
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
| |
Collapse
|
26
|
Effect of altered innervation and thyroid hormones on myosin heavy chain expression and fiber type transitions: a mini-review. Histochem Cell Biol 2014; 143:123-30. [DOI: 10.1007/s00418-014-1276-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2014] [Indexed: 01/19/2023]
|
27
|
Genetic Dissection of the Physiological Role of Skeletal Muscle in Metabolic Syndrome. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/635146] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The primary deficiency underlying metabolic syndrome is insulin resistance, in which insulin-responsive peripheral tissues fail to maintain glucose homeostasis. Because skeletal muscle is the major site for insulin-induced glucose uptake, impairments in skeletal muscle’s insulin responsiveness play a major role in the development of insulin resistance and type 2 diabetes. For example, skeletal muscle of type 2 diabetes patients and their offspring exhibit reduced ratios of slow oxidative muscle. These observations suggest the possibility of applying muscle remodeling to recover insulin sensitivity in metabolic syndrome. Skeletal muscle is highly adaptive to external stimulations such as exercise; however, in practice it is often not practical or possible to enforce the necessary intensity to obtain measurable benefits to the metabolic syndrome patient population. Therefore, identifying molecular targets for inducing muscle remodeling would provide new approaches to treat metabolic syndrome. In this review, the physiological properties of skeletal muscle, genetic analysis of metabolic syndrome in human populations and model organisms, and genetically engineered mouse models will be discussed in regard to the prospect of applying skeletal muscle remodeling as possible therapy for metabolic syndrome.
Collapse
|
28
|
Bryantsev AL, Duong S, Brunetti TM, Chechenova MB, Lovato TL, Nelson C, Shaw E, Uhl JD, Gebelein B, Cripps RM. Extradenticle and homothorax control adult muscle fiber identity in Drosophila. Dev Cell 2013; 23:664-73. [PMID: 22975331 DOI: 10.1016/j.devcel.2012.08.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 06/23/2012] [Accepted: 08/06/2012] [Indexed: 10/27/2022]
Abstract
Here we identify a key role for the homeodomain proteins Extradenticle (Exd) and Homothorax (Hth) in the specification of muscle fiber fate in Drosophila. exd and hth are expressed in the fibrillar indirect flight muscles but not in tubular jump muscles, and manipulating exd or hth expression converts one muscle type into the other. In the flight muscles, exd and hth are genetically upstream of another muscle identity gene, salm, and are direct transcriptional regulators of the signature flight muscle structural gene, Actin88F. Exd and Hth also impact muscle identity in other somatic muscles of the body by cooperating with Hox factors. Because mammalian orthologs of exd and hth also contribute to muscle gene regulation, our studies suggest that an evolutionarily conserved genetic pathway determines muscle fiber differentiation.
Collapse
Affiliation(s)
- Anton L Bryantsev
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Kostrominova TY, Reiner DS, Haas RH, Ingermanson R, McDonough PM. Automated methods for the analysis of skeletal muscle fiber size and metabolic type. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 306:275-332. [PMID: 24016528 DOI: 10.1016/b978-0-12-407694-5.00007-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
It is of interest to quantify the size, shape, and metabolic subtype of skeletal muscle fibers in many areas of biomedical research. To do so, skeletal muscle samples are sectioned transversely to the length of the muscle and labeled for extracellular or membrane proteins to delineate the fiber boundaries and additionally for biomarkers related to function or metabolism. The samples are digitally photographed and the fibers "outlined" for quantification of fiber cross-sectional area (CSA) using pointing devices interfaced to a computer, which is tedious, prone to error, and can be nonobjective. Here, we review methods for characterizing skeletal muscle fibers and describe new automated techniques, which rapidly quantify CSA and biomarkers. We discuss the applications of these methods to the characterization of mitochondrial dysfunctions, which underlie a variety of human afflictions, and we present a novel approach, utilizing images from the online Human Protein Atlas to predict relationships between fiber-specific protein expression, function, and metabolism.
Collapse
|
30
|
SOUKUP T, SULIMENKO V, MARKOVÁ V, KOPECKÁ K, ZACHAŘOVÁ G, PALEČEK J. Expression of the Skeletal Calsequestrin Isoform in Normal and Regenerated Skeletal Muscles and in the Hearts of Rats With Altered Thyroid Status. Physiol Res 2012; 61:575-86. [DOI: 10.33549/physiolres.932416] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We have investigated expression of skeletal calsequestrin (CSQ1) and fiber type composition in normal and regenerated fast and slow skeletal muscles and in the left heart ventricles of euthyroid (EU), hypothyroid (HY) and hyperthyroid (TH) adult inbred Lewis strain rats. The CSQ1 level was determined by SDS-PAGE followed by Western blot analysis. CSQ1 gene expression was assessed using reverse transcription and subsequent real time polymerase chain reaction. Muscle regeneration was achieved by intramuscular grafting of either soleus or extensor digitorum longus (EDL) from 3- to 4-week-old rats to either EDL or soleus muscle of 2-month-old rats. The fiber type composition was assessed by a stereological method applied to stained muscle cross sections. We found that the protein and mRNA levels for CSQ1 were highest in the EDL muscle, the relative CSQ1 protein levels in the soleus muscle were two times lower and the transcript levels more than 5 times lower compared to the EDL. In the left heart ventricle, protein isoform and CSQ1 transcript were also present, although at protein level, CSQ1 was hardly detectable. TH status increased and HY status decreased the expression of CSQ1 in the EDL, but its relative levels in the soleus and in the heart did not change. The regenerated soleus transplanted into EDL, as well as EDL transplanted into soleus exhibited protein and mRNA levels of CSQ1 corresponding to the host muscle and not to the graft source. TH status increased the percentages of the fastest 2X/D and 2B fibers at the expense of slow type 1 and fast 2A fibers in the EDL and that of fast 2A fibers in the soleus at the expense of slow type 1 fibers. HY status led to converse fiber type changes. We suggest that the observed changes in CSQ1 levels in TH and HY compared to EU rats can be related to fiber type changes caused by alteration of the thyroid status rather than to the direct effect of thyroid hormones on CSQ1 gene expression.
Collapse
Affiliation(s)
- T. SOUKUP
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | | | | | | | | | |
Collapse
|
31
|
Schiaffino S. Tubular aggregates in skeletal muscle: just a special type of protein aggregates? Neuromuscul Disord 2011; 22:199-207. [PMID: 22154366 DOI: 10.1016/j.nmd.2011.10.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 09/14/2011] [Accepted: 10/10/2011] [Indexed: 01/28/2023]
Abstract
Tubular aggregates are inclusions, usually found in type II muscle fibers and in males, consisting of regular arrays of tubules derived from the sarcoplasmic reticulum. Tubular aggregates are associated with a wide variety of muscle disorders, including poorly defined "tubular aggregate myopathies" characterized by weakness and/or myalgia and/or cramps, and are also present in different mouse models, including normal aging muscles. The mechanism(s) responsible for inducing the formation of these structures have not been identified, because of the slow time course of their development in vivo, several months in mice. However, identical structures are formed in a few hours in rat muscles kept in vitro in hypoxic medium. Here I suggest that tubular aggregates result from reshaping of sarcoplasmic reticulum caused by misfolding and aggregation of membrane proteins and thus represent a special type of "protein aggregates" due to altered proteostasis.
Collapse
Affiliation(s)
- Stefano Schiaffino
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy; Consiglio Nazionale delle Ricerche Institute of Neuroscience, Padova, Italy.
| |
Collapse
|
32
|
Influence of Differences in Exercise-intensity and Kilograms/Set on Energy Expenditure During and After Maximally Explosive Resistance Exercise. INTERNATIONAL JOURNAL OF EXERCISE SCIENCE 2011; 4:273-282. [PMID: 27182368 PMCID: PMC4738920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
With resistance exercise, greater intensity typically elicits increased energy expenditure, but heavier loads require that the lifter perform more sets of fewer repetitions, which alters the kilograms lifted per set. Thus, the effect of exercise-intensity on energy expenditure has yielded varying results, especially with explosive resistance exercise. This study was designed to examine the effect of exercise-intensity and kilograms/set on energy expenditure during explosive resistance exercise. Ten resistance-trained men (22±3.6 years; 84±6.4 kg, 180±5.1 cm, and 13±3.8 %fat) performed squat and bench press protocols once/week using different exercise-intensities including 48% (LIGHT-48), 60% (MODERATE-60), and 72% of 1-repetition-maximum (1-RM) (HEAVY-72), plus a no-exercise protocol (CONTROL). To examine the effects of kilograms/set, an additional protocol using 72% of 1-RM was performed (HEAVY-72MATCHED) with kilograms/set matched with LIGHT-48 and MODERATE-60. LIGHT-48 was 4 sets of 10 repetitions (4×10); MODERATE-60 4×8; HEAVY-72 5×5; and HEAVY-72MATCHED 4×6.5. Eccentric and concentric repetition speeds, ranges-of-motion, rest-intervals, and total kilograms were identical between protocols. Expired air was collected continuously throughout each protocol using a metabolic cart, [Blood lactate] using a portable analyzer, and bench press peak power were measured. Rates of energy expenditure were significantly greater (p≤0.05) with LIGHT-48 and HEAVY-72MATCHED than HEAVY-72 during squat (7.3±0.7; 6.9±0.6 > 6.1±0.7 kcal/min), bench press (4.8±0.3; 4.7±0.3 > 4.0±0.4 kcal/min), and +5min after (3.7±0.1; 3.7±0.2 > 3.3±0.3 kcal/min), but there were no significant differences in total kcal among protocols. Therefore, exercise-intensity may not effect energy expenditure with explosive contractions, but light loads (~50% of 1-RM) may be preferred because of higher rates of energy expenditure, and since heavier loading requires more sets with lower kilograms/set.
Collapse
|
33
|
Abstract
Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.
Collapse
Affiliation(s)
- Stefano Schiaffino
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| |
Collapse
|
34
|
Novák P, Soukup T. Calsequestrin distribution, structure and function, its role in normal and pathological situations and the effect of thyroid hormones. Physiol Res 2011; 60:439-52. [PMID: 21401301 DOI: 10.33549/physiolres.931989] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Calsequestrin is the main calcium binding protein of the sarcoplasmic reticulum, serving as an important regulator of Ca(2+). In mammalian muscles, it exists as a skeletal isoform found in fast- and slow-twitch skeletal muscles and a cardiac isoform expressed in the heart and slow-twitch muscles. Recently, many excellent reviews that summarised in great detail various aspects of the calsequestrin structure, localisation or function both in skeletal and cardiac muscle have appeared. The present review focuses on skeletal muscle: information on cardiac tissue is given, where differences between both tissues are functionally important. The article reviews the known multiple roles of calsequestrin including pathology in order to introduce this topic to the broader scientific community and to stimulate an interest in this protein. Newly we describe our results on the effect of thyroid hormones on skeletal and cardiac calsequestrin expression and discuss them in the context of available literary data on this topic.
Collapse
Affiliation(s)
- P Novák
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | |
Collapse
|
35
|
|
36
|
|
37
|
Abstract
Muscle performance is in part dictated by muscle fibre composition and a precise understanding of the genetic and acquired factors that determine the fibre type profile is important in sport science, but is also relevant to neuromuscular diseases and to metabolic diseases, such as type 2 diabetes. The dissection of the signalling pathways that determine or modulate the muscle fibre phenotype has thus potential clinical significance. In this brief review, I examine the evolution of the notion of muscle fibre types, discuss some aspects related to species differences, point at problems in the interpretation of transgenic and knockout models and show how in vivo transfection can be used to identify regulatory factors involved in fibre type diversification, focusing on the calcineurin-nuclear factor of activated T cells (NFAT) pathway.
Collapse
Affiliation(s)
- S Schiaffino
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
| |
Collapse
|
38
|
Schiaffino S. Differentiation of the Contractile Apparatus in Vertebrate Skeletal Muscles. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/11250007209430054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
39
|
Eng CM, Smallwood LH, Rainiero MP, Lahey M, Ward SR, Lieber RL. Scaling of muscle architecture and fiber types in the rat hindlimb. J Exp Biol 2008; 211:2336-45. [DOI: 10.1242/jeb.017640] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The functional capacity of a muscle is determined by its architecture and metabolic properties. Although extensive analyses of muscle architecture and fiber type have been completed in a large number of muscles in numerous species, there have been few studies that have looked at the interrelationship of these functional parameters among muscles of a single species. Nor have the architectural properties of individual muscles been compared across species to understand scaling. This study examined muscle architecture and fiber type in the rat (Rattus norvegicus) hindlimb to examine each muscle's functional specialization. Discriminant analysis demonstrated that architectural properties are a greater predictor of muscle function (as defined by primary joint action and anti-gravity or non anti-gravity role)than fiber type. Architectural properties were not strictly aligned with fiber type, but when muscles were grouped according to anti-gravity versusnon-anti-gravity function there was evidence of functional specialization. Specifically, anti-gravity muscles had a larger percentage of slow fiber type and increased muscle physiological cross-sectional area. Incongruities between a muscle's architecture and fiber type may reflect the variability of functional requirements on single muscles, especially those that cross multiple joints. Additionally, discriminant analysis and scaling of architectural variables in the hindlimb across several mammalian species was used to explore whether any functional patterns could be elucidated within single muscles or across muscle groups. Several muscles deviated from previously described muscle architecture scaling rules and there was large variability within functional groups in how muscles should be scaled with body size. This implies that functional demands placed on muscles across species should be examined on the single muscle level.
Collapse
Affiliation(s)
- Carolyn M. Eng
- Departments of Orthopaedic Surgery and Bioengineering, University of California and Veterans Administration Medical Centers, San Diego, CA,USA
| | - Laura H. Smallwood
- Departments of Orthopaedic Surgery and Bioengineering, University of California and Veterans Administration Medical Centers, San Diego, CA,USA
| | - Maria Pia Rainiero
- Department of Radiology, University of California and Veterans Administration Medical Centers, San Diego, CA, USA
| | - Michele Lahey
- Departments of Orthopaedic Surgery and Bioengineering, University of California and Veterans Administration Medical Centers, San Diego, CA,USA
| | - Samuel R. Ward
- Department of Radiology, University of California and Veterans Administration Medical Centers, San Diego, CA, USA
| | - Richard L. Lieber
- Departments of Orthopaedic Surgery and Bioengineering, University of California and Veterans Administration Medical Centers, San Diego, CA,USA
| |
Collapse
|
40
|
Kaakinen M, Papponen H, Metsikkö K. Microdomains of endoplasmic reticulum within the sarcoplasmic reticulum of skeletal myofibers. Exp Cell Res 2007; 314:237-45. [PMID: 17999928 DOI: 10.1016/j.yexcr.2007.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 09/14/2007] [Accepted: 10/06/2007] [Indexed: 10/22/2022]
Abstract
The relationship between the endoplasmic reticulum (ER) and the sarcoplasmic reticulum (SR) of skeletal muscle cells has remained obscure. In this study, we found that ER- and SR-specific membrane proteins exhibited diverse solubility properties when extracted with mild detergents. Accordingly, the major SR-specific protein Ca(2+)-ATPase (SERCA) remained insoluble in Brij 58 and floated in sucrose gradients while typical ER proteins were partially or fully soluble. Sphingomyelinase treatment rendered SERCA soluble in Brij 58. Immunofluorescence staining for resident ER proteins revealed dispersed dots over I bands contrasting the continuous staining pattern of SERCA. Infection of isolated myofibers with enveloped viruses indicated that interfibrillar protein synthesis occurred. Furthermore, we found that GFP-tagged Dad1, able to incorporate into the oligosaccharyltransferase complex, showed the dot-like structures but the fusion protein was also present in membranes over the Z lines. This behaviour mimics that of cargo proteins that accumulated over the Z lines when blocked in the ER. Taken together, the results suggest that resident ER proteins comprised Brij 58-soluble microdomains within the insoluble SR membrane. After synthesis and folding in the ER-microdomains, cargo proteins and non-incorporated GFP-Dad1 diffused into the Z line-flanking compartment which likely represents the ER exit sites.
Collapse
Affiliation(s)
- Mika Kaakinen
- Department of Anatomy and Cell Biology, P.O. Box 5000 (Aapistie 7), FIN-90014 University of Oulu, Finland
| | | | | |
Collapse
|
41
|
Schiaffino S, Sandri M, Murgia M. Activity-dependent signaling pathways controlling muscle diversity and plasticity. Physiology (Bethesda) 2007; 22:269-78. [PMID: 17699880 DOI: 10.1152/physiol.00009.2007] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A variety of fiber types with different contractile and metabolic properties is present in mammalian skeletal muscle. The fiber-type profile is controlled by nerve activity via specific signaling pathways, whose identification may provide potential therapeutic targets for the prevention and treatment of metabolic and neuromuscular diseases.
Collapse
|
42
|
Mazzetti S, Douglass M, Yocum A, Harber M. Effect of Explosive versus Slow Contractions and Exercise Intensity on Energy Expenditure. Med Sci Sports Exerc 2007; 39:1291-301. [PMID: 17762362 DOI: 10.1249/mss.0b013e318058a603] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVE The primary purpose of this study was to compare the effects of explosive versus slow contractions on the rate of energy expenditure during and after resistance exercise. METHODS Nine men (20 +/- 2.5 yr) performed three exercise protocols using a plate-loaded squat machine, and a no-exercise (CONTROL) session in a randomly assigned, counterbalanced order. Subjects performed squats using either two second (SLOW) or explosive concentric contractions (EXPL), but identical repetitions (8), sets (4), and loads (60% 1RM). A secondary objective was to compare high- versus moderate-intensity exercise. Thus, a third protocol was performed that also used explosive contractions, with heavier loads (80% 1RM) and six sets of four reps (HEAVYEXPL). Eccentric reps (2 s), work (reps x sets x load), range of motion, and rest intervals between sets (90 s) were identical among all three protocols. Expired air was collected continuously for 20 min before, during, and 1 h after exercise and for about 1.5 h during CONTROL. Blood samples (25 microL) were collected before, immediately after, and 15, 30, 45, and 60 min after each protocol, and these samples were analyzed for blood lactate (mM). RESULTS Average rates of energy expenditure (kcal.min) were significantly greater (P <or= 0.05) during (7.27 +/- 2.00 > 6.43 +/- 1.64 and 6.25 +/- 1.55, respectively) and after (2.54 +/- 1.44 > 2.38 +/- 1.31 and 2.21 +/- 1.08, respectively) EXPL compared with SLOW and HEAVYEXPL, despite significantly (P <or= 0.05) greater blood lactate after SLOW. CONCLUSION Squat exercise using explosive contractions and moderate intensity induced a greater increase in the rate of energy expenditure than squats using slow contractions or high intensity in all subjects tested. Thus, by using explosive contractions and moderate exercise intensity, experienced recreational exercisers can increase their energy expenditure during and after resistance exercise, and this could enhance weight-loss adaptations.
Collapse
Affiliation(s)
- Scott Mazzetti
- Human Performance Center, Anderson University, Anderson, IN, USA.
| | | | | | | |
Collapse
|
43
|
Baryshnikova LM, Croes SA, von Bartheld CS. Classification and Development of Myofiber Types in the Superior Oblique Extraocular Muscle of Chicken. Anat Rec (Hoboken) 2007; 290:1526-41. [DOI: 10.1002/ar.20614] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
44
|
Coulet B, Lacombe F, Lazerges C, Daussin PA, Rossano B, Micallef JP, Chammas M, Reyne Y, Bacou F. Short- or long-term effects of adult myoblast transfer on properties of reinnervated skeletal muscles. Muscle Nerve 2006; 33:254-64. [PMID: 16281277 DOI: 10.1002/mus.20459] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Skeletal muscle demonstrates a force deficit after repair of injured peripheral nerves. Data from the literature indicate that myoblast transfer enhances recovery of muscle function. Thus, we tested the hypothesis that transfer of adult myoblasts improves the properties of reinnervated rabbit tibialis anterior (TA) muscles in both the short term (4 months) and long term (14 months). Two months after transection and immediate suture of the common peroneal nerve, TA muscles were made to degenerate by cardiotoxin injection and then transplanted with adult myoblasts cultured for 13 days. Under these conditions, muscles studied at 4 months were heavier, contained larger fibers, and developed a significantly higher maximal force than muscles that had only been denervated-reinnervated. In the long term, although muscles made to degenerate were heavier and developed a significantly higher maximal force than denervated-reinnervated muscles, myoblast transfer failed to improve these parameters. However, the overall characteristics of long-term operated muscles tended clearly to approach those of the controls. Taken together, these results may have significant implications in certain orthopedic contexts, particularly after immediate or delayed muscle reinnervation.
Collapse
Affiliation(s)
- Bertrand Coulet
- UMR 866 Différenciation Cellulaire et Croissance, Institut National de la Recherche Agronomique (INRA), Montpellier, France
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Abstract
Extraocular muscle is fundamentally distinct from other skeletal muscles. Here, we review the biological organization of the extraocular muscles with the intent of understanding this novel muscle group in the context of oculomotor system function. The specific objectives of this review are threefold. The first objective is to understand the anatomic arrangement of the extraocular muscles and their compartmental or layered organization in the context of a new concept of orbital mechanics, the active pulley hypothesis. The second objective is to present an integrated view of the morphologic, cellular, and molecular differences between extraocular and the more traditional skeletal muscles. The third objective is to relate recent data from functional and molecular biology studies to the established extraocular muscle fiber types. Developmental mechanisms that may be responsible for the divergence of the eye muscles from a skeletal muscle prototype also are considered. Taken together, a multidisciplinary understanding of extraocular muscle biology in health and disease provides insights into oculomotor system function and malfunction. Moreover, because the eye muscles are selectively involved or spared in a variety of neuromuscular diseases, knowledge of their biology may improve current pathogenic models of and treatments for devastating systemic diseases.
Collapse
Affiliation(s)
- Robert F Spencer
- Department of Anatomy, Medical College of Virginia, Richmond, VA 23298, USA
| | | |
Collapse
|
46
|
Orliaguet G, Riou B, Leguen M. [Postnatal maturation of the diaphragm muscle: ultrastructural and functional aspects]. ACTA ACUST UNITED AC 2004; 23:482-94. [PMID: 15158239 DOI: 10.1016/j.annfar.2003.12.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2003] [Accepted: 12/19/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVE In the diaphragm muscle, postnatal maturation is associated with major histological and biochemical modifications, as well as a progressive development of the sarcoplasmic reticulum (SR), which in turn are responsible for the progressive postnatal improvement in diaphragmatic contractility. However, the mechanisms by which postnatal maturation induces this improvement in diaphragmatic contractility remain poorly understood and controversial. The aim of this review is to analyze the data from the literature regarding the process involved in the postnatal improvement in diaphragmatic contractility. DATA SOURCES References obtained from Pubmed((R)) databank using keywords (diaphragm muscle, postnatal maturation, contractility, muscular fatigue, cross-bridge). DATA SYNTHESIS From a cytological point of view, the postnatal development of the diaphragm muscle is processed in two successive generations of fiber types, corresponding to the progressive adaptation of the diaphragm muscle to its physiological function. Indeed, the proportion in type I (slow, aerobic) and type IIB fibers (fast, anaerobic) progressively increases with postnatal maturation, while the proportion in type IIA fibers (fast, intermediate) progressively decreases. The histochemical classification of the type of fiber corresponds to the expression of the different isoforms of myosin heavy chains (MHC). Two types of MHC: MHC embryologic (MCH-emb) and MHC neonatal (MCH-neo), and one type of myosin light chains (MLC) are expressed in the foetal skeletal muscles, then are progressively eliminated during postnatal maturation. For many authors, this progressive transition from immature MHC (MCH-emb and neo) to adult MHC (by chronological order of appearance: MHC-2A, MHC-lente, MHC-2X, MHC-2B) could be responsible for the progressive improvement in postnatal diaphragmatic contractility. This transition could be modulated by external factors, mainly including neural and hormonal stimuli. For others, this transition in MHC expression do not play a major role, and other factors, including the postnatal maturation of the ryanodine receptor (RyR) or developmental changes in cross-bridges (CB) properties should play a central role. The most recent hypotheses proposed included the possibility of a postnatal transition in the expression of structural proteins, which are playing a major role in the maintenance of the stability of the sarcomer, and therefore in force generation.
Collapse
Affiliation(s)
- G Orliaguet
- Département d'anesthésie-réanimation chirurgicale, CHU Necker-Enfants-Malades, AP-HP, 7574 Paris cedex 15, France.
| | | | | |
Collapse
|
47
|
Nori A, Lin PJ, Cassetti A, Villa A, Bayer KU, Volpe P. Targeting of alpha-kinase-anchoring protein (alpha KAP) to sarcoplasmic reticulum and nuclei of skeletal muscle. Biochem J 2003; 370:873-80. [PMID: 12470297 PMCID: PMC1223226 DOI: 10.1042/bj20021624] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2002] [Revised: 11/22/2002] [Accepted: 12/06/2002] [Indexed: 12/25/2022]
Abstract
The sarcoplasmic reticulum (SR) plays a key role in excitation/contraction coupling of skeletal muscle. The SR is composed of two continuous yet heterogeneous membrane compartments, the free or longitudinal SR and cisternal SR. Cisternal SR is made up of free SR membrane, enriched in Ca(2+) pumps, and junctional SR (jSR) membrane, enriched in ryanodine-sensitive Ca(2+)-release channels, and contains calsequestrin within its lumen. Protein phosphorylation mediated by the Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II) has significant, distinct regulatory roles in both Ca(2+) uptake and Ca(2+) release. Kinase-anchoring proteins (KAPs) constitute a novel mechanism for achieving cell compartmentalization of effectors in phosphorylation pathways. Here, targeting of alpha KAP, a CaM kinase II-anchoring protein encoded within the alpha-CaM kinase II gene, was studied in transgenic skeletal muscle fibres of the adult rat soleus. The transgenes were epitope-tagged versions of alpha KAP and of a deletion mutant, allowing their specific immunodetection against the wild-type background. Our results show that alpha KAP is largely localized at the free SR and thus near the Ca(2+) pump, a protein that can be modulated by CaM kinase II phosphorylation. Only minor co-localization was observed with the jSR ryanodine-sensitive Ca(2+)-release channel, which is a potential CaM kinase II target. In non-muscle cells, recombinant alpha KAP is targeted to endoplasmic reticulum (ER). Both ER and SR targeting requires the N-terminal hydrophobic region of alpha KAP. An unexpected additional specific localization that does not require the N-terminus was found in the nucleus, providing a first clue of how CaM kinase II can fulfil its nuclear functions in skeletal muscle.
Collapse
Affiliation(s)
- Alessandra Nori
- Dipartimento di Scienze Biomediche Sperimentali dell'Università di Padova, viale G. Colombo 3, 35121 Padova, Italy
| | | | | | | | | | | |
Collapse
|
48
|
|
49
|
Eddinger TJ, Meer DP. Smooth muscle heterogeneity: Does the striated muscle model apply? Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
50
|
Kirsch RF, Boskov D, Rymer WZ. Muscle stiffness during transient and continuous movements of cat muscle: perturbation characteristics and physiological relevance. IEEE Trans Biomed Eng 1994; 41:758-70. [PMID: 7927398 DOI: 10.1109/10.310091] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Continuous stochastic position perturbations are an attractive alternative to transient perturbations in muscle and reflex studies because they allow efficient characterization of system properties. However, the relevance of the results obtained from stochastic perturbations remains unclear because they may induce a state change in muscle properties. We addressed this concern by comparing the force and stiffness responses of isolated muscles of the decerebrate cat elicited by stochastic perturbations to those evoked by "step" stretches of similar amplitudes. Muscle stiffness during stochastic perturbations was found to be predominantly linear and elastic in nature for a given operating point, showing no evidence of instantaneous amplitude-dependent nonlinearities, even during large movements. In contrast, force responses evoked by step stretches were found to be mainly viscous in nature and nonlinear for larger stretches, with only a small maintained (elastic) component. Stiffness magnitude decreased with displacement amplitude for both stochastic and step perturbations. Our results are largely consistent with the crossbridge theory of muscle contraction, indicating that transient and continuous displacements evoke different, although functionally relevant, aspects of muscle behavior. These differences have several implications for the neural control of posture and movement, and for the design of perturbations appropriate for its study.
Collapse
Affiliation(s)
- R F Kirsch
- Rehabilitation Engineering Center, MetroHealth Medical Center, Cleveland, OH 44109
| | | | | |
Collapse
|