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  • 1.
    Cristea, Alexander
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Qaisar, Rizwan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Karlsson Edlund, Patrick
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Lindblad, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Bengtsson, Ewert
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Larsson, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Effects of aging and gender on the spatial organization of nuclei in single human skeletal muscle cells2010In: Aging Cell, ISSN 1474-9718, E-ISSN 1474-9726, Vol. 9, no 5, p. 685-697Article in journal (Refereed)
    Abstract [en]

    The skeletal muscle fibre is a syncitium where each myonucleus regulates the gene products in a finite volume of the cytoplasm, i.e., the myonuclear domain (MND). We analysed aging- and gender-related effects on myonuclei organization and the MND size in single muscle fibres from six young (21–31 years) and nine old men (72–96 years), and from six young (24–32 years) and nine old women (65–96 years), using a novel image analysis algorithm applied to confocal images. Muscle fibres were classified according to myosin heavy chain (MyHC) isoform expression. Our image analysis algorithm was effective in determining the spatial organization of myonuclei and the distribution of individual MNDs along the single fibre segments. Significant linear relations were observed between MND size and fibre size, irrespective age, gender and MyHC isoform expression. The spatial organization of individual myonuclei, calculated as the distribution of nearest neighbour distances in 3D, and MND size were affected in old age, but changes were dependent on MyHC isoform expression. In type I muscle fibres, average NN-values were lower and showed an increased variability in old age, reflecting an aggregation of myonuclei in old age. Average MND size did not change in old age, but there was an increased MND size variability. In type IIa fibres, average NN-values and MND sizes were lower in old age, reflecting the smaller size of these muscle fibres in old age. It is suggested that these changes have a significant impact on protein synthesis and degradation during the aging process.

  • 2.
    Liu, Jing-Xia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Höglund, Anna-Stina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Karlsson, Patrick
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Lindblad, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Qaisar, Rizwan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Aare, Sudhakar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Bengtsson, Ewert
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Larsson, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Myonuclear domain size and myosin isoform expression in muscle fibres from mammals representing a 100 000-fold difference in body size2009In: Experimental Physiology, ISSN 0958-0670, E-ISSN 1469-445X, Vol. 94, no 1, p. 117-129Article in journal (Refereed)
    Abstract [en]

    This comparative study of myonuclear domain (MND) size in mammalian species representing a 100 000-fold difference in body mass, ranging from 25 g to 2500 kg, was undertaken to improve our understanding of myonuclear organization in skeletal muscle fibres. Myonuclear domain size was calculated from three-dimensional reconstructions in a total of 235 single muscle fibre segments at a fixed sarcomere length. Irrespective of species, the largest MND size was observed in muscle fibres expressing fast myosin heavy chain (MyHC) isoforms, but in the two smallest mammalian species studied (mouse and rat), MND size was not larger in the fast-twitch fibres expressing the IIA MyHC isofom than in the slow-twitch type I fibres. In the larger mammals, the type I fibres always had the smallest average MND size, but contrary to mouse and rat muscles, type IIA fibres had lower mitochondrial enzyme activities than type I fibres. Myonuclear domain size was highly dependent on body mass in the two muscle fibre types expressed in all species, i.e. types I and IIA. Myonuclear domain size increased in muscle fibres expressing both the β/slow (type I; r= 0.84, P < 0.001) and the fast IIA MyHC isoform (r= 0.90; P < 0.001). Thus, MND size scales with body size and is highly dependent on muscle fibre type, independent of species. However, myosin isoform expression is not the sole protein determining MND size, and other protein systems, such as mitochondrial proteins, may be equally or more important determinants of MND size.

  • 3.
    Qaisar, Rizwan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Myonuclear Organization and Regulation of Muscle Contraction in Single Muscle Fibres: Effects of Ageing, Gender, Species, Endocrine Factors and Muscle Size2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The skeletal muscle fibre is a syncitium where each myonucleus regulates the gene products in a finite volume of cytoplasm i.e., the myonuclear domain (MND). A novel image analysis algorithm applied to confocal images, analyzing MND size and myonuclear spatial distribution in 3-dimensions in single skeletal muscle fibres has been used in this project. The goal was to explore the modulation of myonuclei count and MND size in response to muscle adaptation processes. The effects of ageing, gender, hormones, muscle hypertrophy and body size were investigated on MND size.

    A strong linear relationship was found between MND size and body size in the muscle fibres from mammals representing a 100,000-fold difference in body size. Independent of species, MND size was highly dependent on MyHC isoform type and mitochondrial contents of skeletal muscle fibres. In hypertrophic mice, a significant effect of MND size on specific force and myosin content was observed. This effect was muscle fibre type-specific and shows that the bigger MNDs in fast-twitch EDL muscle fibres are optimally tuned for force production while smaller MNDs in slow-twitch soleus muscle fibres have a much more dynamic range of hypertrophy without functional compromise. This indicates a critical volume individual myonuclei can support efficiently for a proportional gain in muscle fibre force and size. In human muscle fibres, spatial organization of myonuclei was affected by both ageing and MyHC isoform expression. In fibres expressing type I MyHC isoform, an increased MND size variability and myonuclear aggregates were observed in old age although average MND size was unchanged. In contrast, in type IIa fibres, the average MND size was smaller reflecting smaller size of muscle fibres. Those changes may influence the transcriptional activity per myonucleus and/or local cooperatively of myonuclei in a gender and muscle fibre-type specific manner. Finally, hormone replacement therapy was shown to negate menopause-related functional impairment in skeletal muscle fibres. The positive effect on force was due to quantitative effect in fibres expressing fast myosin isoform while the effect was both quantitative and qualitative in fibres expressing slow myosin isoform. The effect on MND size was fibre type dependent and was achieved by significantly reducing domain size in slow- but not the fast-twitch muscle fibres.

    Together, our data suggest that modulation of myonuclei count and MND size is a mechanism contributing to remodelling of skeletal muscle in muscle adaptation process. These findings should be considered when developing therapeutic approaches towards restoring muscle mass and strength in muscle wasting conditions.

    List of papers
    1. Myonuclear domain size and myosin isoform expression in muscle fibres from mammals representing a 100 000-fold difference in body size
    Open this publication in new window or tab >>Myonuclear domain size and myosin isoform expression in muscle fibres from mammals representing a 100 000-fold difference in body size
    Show others...
    2009 (English)In: Experimental Physiology, ISSN 0958-0670, E-ISSN 1469-445X, Vol. 94, no 1, p. 117-129Article in journal (Refereed) Published
    Abstract [en]

    This comparative study of myonuclear domain (MND) size in mammalian species representing a 100 000-fold difference in body mass, ranging from 25 g to 2500 kg, was undertaken to improve our understanding of myonuclear organization in skeletal muscle fibres. Myonuclear domain size was calculated from three-dimensional reconstructions in a total of 235 single muscle fibre segments at a fixed sarcomere length. Irrespective of species, the largest MND size was observed in muscle fibres expressing fast myosin heavy chain (MyHC) isoforms, but in the two smallest mammalian species studied (mouse and rat), MND size was not larger in the fast-twitch fibres expressing the IIA MyHC isofom than in the slow-twitch type I fibres. In the larger mammals, the type I fibres always had the smallest average MND size, but contrary to mouse and rat muscles, type IIA fibres had lower mitochondrial enzyme activities than type I fibres. Myonuclear domain size was highly dependent on body mass in the two muscle fibre types expressed in all species, i.e. types I and IIA. Myonuclear domain size increased in muscle fibres expressing both the β/slow (type I; r= 0.84, P < 0.001) and the fast IIA MyHC isoform (r= 0.90; P < 0.001). Thus, MND size scales with body size and is highly dependent on muscle fibre type, independent of species. However, myosin isoform expression is not the sole protein determining MND size, and other protein systems, such as mitochondrial proteins, may be equally or more important determinants of MND size.

    National Category
    Physiology
    Identifiers
    urn:nbn:se:uu:diva-87940 (URN)10.1113/expphysiol.2008.043877 (DOI)000261961800014 ()18820003 (PubMedID)
    Available from: 2009-01-15 Created: 2009-01-15 Last updated: 2018-12-02Bibliographically approved
    2. Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?
    Open this publication in new window or tab >>Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?
    Show others...
    2012 (English)In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 26, no 3, p. 1077-1085Article in journal (Refereed) Published
    Abstract [en]

    Muscle force is typically proportional to muscle size, resulting in constant force normalized to muscle fiber cross-sectional area (specific force). Mice overexpressing insulin-like growth factor-1 (IGF-1) exhibit a proportional gain in muscle force and size, but not the myostatin-deficient mice. In an attempt to explore the role of the cytoplasmic volume supported by individual myonuclei [myonuclear domain (MND) size] on functional capacity of skeletal muscle, we have investigated specific force in relation to MND and the content of the molecular motor protein, myosin, at the single muscle fiber level from myostatin-knockout (Mstn(-/-)) and IGF-1-overexpressing (mIgf1(+/+)) mice. We hypothesize that the addition of extra myonuclei is a prerequisite for maintenance of specific force during muscle hypertrophy. A novel algorithm was used to measure individual MNDs in 3 dimensions along the length of single muscle fibers from the fast-twitch extensor digitorum longus and the slow-twitch soleus muscle. A significant effect of the size of individual MNDs in hypertrophic muscle fibers on both specific force and myosin content was observed. This effect was muscle cell type specific and suggested there is a critical volume individual myonuclei can support efficiently. The large MNDs found in fast muscles of Mstn(-/-) mice were correlated with the decrement in specific force and myosin content in Mstn(-/-) muscles. Thus, myostatin inhibition may not be able to maintain the appropriate MND for optimal function.-Qaisar, R., Renaud, G., Morine, K., Barton, E. R., Sweeney, H. L., Larsson, L. Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?

    National Category
    Physiology
    Identifiers
    urn:nbn:se:uu:diva-166951 (URN)10.1096/fj.11-192195 (DOI)000300949300012 ()22125316 (PubMedID)
    Available from: 2012-01-17 Created: 2012-01-17 Last updated: 2018-01-12Bibliographically approved
    3. Effects of aging and gender on the spatial organization of nuclei in single human skeletal muscle cells
    Open this publication in new window or tab >>Effects of aging and gender on the spatial organization of nuclei in single human skeletal muscle cells
    Show others...
    2010 (English)In: Aging Cell, ISSN 1474-9718, E-ISSN 1474-9726, Vol. 9, no 5, p. 685-697Article in journal (Refereed) Published
    Abstract [en]

    The skeletal muscle fibre is a syncitium where each myonucleus regulates the gene products in a finite volume of the cytoplasm, i.e., the myonuclear domain (MND). We analysed aging- and gender-related effects on myonuclei organization and the MND size in single muscle fibres from six young (21–31 years) and nine old men (72–96 years), and from six young (24–32 years) and nine old women (65–96 years), using a novel image analysis algorithm applied to confocal images. Muscle fibres were classified according to myosin heavy chain (MyHC) isoform expression. Our image analysis algorithm was effective in determining the spatial organization of myonuclei and the distribution of individual MNDs along the single fibre segments. Significant linear relations were observed between MND size and fibre size, irrespective age, gender and MyHC isoform expression. The spatial organization of individual myonuclei, calculated as the distribution of nearest neighbour distances in 3D, and MND size were affected in old age, but changes were dependent on MyHC isoform expression. In type I muscle fibres, average NN-values were lower and showed an increased variability in old age, reflecting an aggregation of myonuclei in old age. Average MND size did not change in old age, but there was an increased MND size variability. In type IIa fibres, average NN-values and MND sizes were lower in old age, reflecting the smaller size of these muscle fibres in old age. It is suggested that these changes have a significant impact on protein synthesis and degradation during the aging process.

    Keywords
    aging, human skeletal muscle, myonuclear domain, 3D imaging
    National Category
    Physiology
    Identifiers
    urn:nbn:se:uu:diva-139870 (URN)10.1111/j.1474-9726.2010.00594.x (DOI)000281897400003 ()20633000 (PubMedID)
    Available from: 2010-12-30 Created: 2010-12-30 Last updated: 2018-12-02Bibliographically approved
    4. Contractile function and myonuclear organization in single fibers from monozygotic female twins discordant for hormone replacement therapy
    Open this publication in new window or tab >>Contractile function and myonuclear organization in single fibers from monozygotic female twins discordant for hormone replacement therapy
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Physiology
    Identifiers
    urn:nbn:se:uu:diva-166952 (URN)
    Available from: 2012-01-17 Created: 2012-01-17 Last updated: 2018-01-12
  • 4.
    Qaisar, Rizwan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Hedström, Yvette
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Kovanen, Vuokko
    Sipila, Sarianna
    Larsson, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Contractile function and myonuclear organization in single fibers from monozygotic female twins discordant for hormone replacement therapyManuscript (preprint) (Other academic)
    Abstract [en]

    Ageing is associated with a decline in muscle mass and strength leading to increased physical dependency in old age. Post-menopausal women experience a greater decline than men of similar age due to a dramatic decrease in sex hormones production. We recruited six monozygous female twin pairs (55 – 59 years old) discordant for postmenopausal hormone replacement therapy (HRT use = 7.8 ± 4.3 years) to investigate the association of HRT with the cytoplasmic domain supported by individual myonuclei (myonuclear domain size, MND) together with specific force at the single fiber level. MyHC isoform content of the fibers was determined using silver-stained SDS-PAGE. HRT use was associated with a significantly smaller (~27%; p < 0.05) mean MND size in muscle fibers expressing the type I but not the IIa MyHC isoform. An increase in specific force was recorded in the HRT user group both in muscle fibers expressing type I (~27%; p < 0.05) and type IIa (~23%; p < 0.05) MyHC isoforms. These positive effects on specific force were fiber-type dependent, i.e., in fast-twitch muscle fibers the increased specific force was primarily caused by an increased force per cross-bridge while slow-twitch fibers relied on both an increase in both number and force per cross-bridge. HRT use had no effect on fiber cross-sectional area (CSA), velocity of unloaded shortening (V0) and relative proportion of MyHC isoforms. In conclusion, HRT has significant positive effects on both regulation of muscle contraction and myonuclei organization in menopausal women, but the response is fiber-type specific.

  • 5.
    Qaisar, Rizwan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Renaud, Guillaume
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Morine, Kevin
    Barton, Elisabeth
    Sweeney, Lee
    Larsson, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?2012In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 26, no 3, p. 1077-1085Article in journal (Refereed)
    Abstract [en]

    Muscle force is typically proportional to muscle size, resulting in constant force normalized to muscle fiber cross-sectional area (specific force). Mice overexpressing insulin-like growth factor-1 (IGF-1) exhibit a proportional gain in muscle force and size, but not the myostatin-deficient mice. In an attempt to explore the role of the cytoplasmic volume supported by individual myonuclei [myonuclear domain (MND) size] on functional capacity of skeletal muscle, we have investigated specific force in relation to MND and the content of the molecular motor protein, myosin, at the single muscle fiber level from myostatin-knockout (Mstn(-/-)) and IGF-1-overexpressing (mIgf1(+/+)) mice. We hypothesize that the addition of extra myonuclei is a prerequisite for maintenance of specific force during muscle hypertrophy. A novel algorithm was used to measure individual MNDs in 3 dimensions along the length of single muscle fibers from the fast-twitch extensor digitorum longus and the slow-twitch soleus muscle. A significant effect of the size of individual MNDs in hypertrophic muscle fibers on both specific force and myosin content was observed. This effect was muscle cell type specific and suggested there is a critical volume individual myonuclei can support efficiently. The large MNDs found in fast muscles of Mstn(-/-) mice were correlated with the decrement in specific force and myosin content in Mstn(-/-) muscles. Thus, myostatin inhibition may not be able to maintain the appropriate MND for optimal function.-Qaisar, R., Renaud, G., Morine, K., Barton, E. R., Sweeney, H. L., Larsson, L. Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?

  • 6.
    Qaisar, Rizwan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Yvette, Hedstrom
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Vuokko, Kovanen
    Sipilä, Sarianna
    Larsson, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Contractile function and myonuclear organization in single fibers from monozygotic female twins discordant for hormone replacement therapyManuscript (preprint) (Other academic)
1 - 6 of 6
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  • nn-NO
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