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Scaling of Motility Speed and Its Temperature Sensitivity in Mammals Representing a 5,500-fold Difference in Body Size
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology. (Prof Lars Larsson)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology. (Prof Lars Larsson)
Univ of Pennsylvania USA, Dpt of Pathobiology, School of Veterrinary Medicin..
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology. (Prof Lars Larsson)
(English)Article in journal (Refereed) Submitted
National Category
Physiology
Research subject
Neurology
Identifiers
URN: urn:nbn:se:uu:diva-123004OAI: oai:DiVA.org:uu-123004DiVA: diva2:311601
Note
kommer att kompletterasAvailable from: 2010-04-22 Created: 2010-04-22 Last updated: 2010-07-31Bibliographically approved
In thesis
1. Celluar and Molecular Mechanisms Underlying Regulation of Skeletal Muscle Contraction in Health and Disease
Open this publication in new window or tab >>Celluar and Molecular Mechanisms Underlying Regulation of Skeletal Muscle Contraction in Health and Disease
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Morphological changes, genetic modifications, and cell functional alterations are not always parallel. Therefore, assessment of skeletal muscle function is an integral part of the etiological approach. The general objective of this thesis was to look into the cellular and molecular events occurring in skeletal muscle contraction in healthy and diseased condition, using a single fiber preparation and a single fiber in vitro motility assay, in an attempt to approach the underlying mechanisms from different physiological angles. In a body size related muscle contractility study, scaling of actin filament sliding speed and its temperature sensitivity has been investigated in mammals covering a 5,500-fold difference in body mass. A profound temperature dependence of actin filament sliding speed over myosin head was demonstrated irrespective of MyHC isoform expression and species. However, the expected body size related scaling within orthologus myosin isoforms between species failed to be maintained at any temperature over 5,500-fold range in body mass, with the larger species frequently having faster in vitro motility speeds than the smaller species. This suggest that apart from the MyHC iso-form expression, other factors such as thin filament proteins and myofilament lattice spacing, may contribute to the scaling related regulation of skeletal muscle contractility. A study of a novel R133W β-tropomyosin mutation on regulation of skeletal muscle contraction in the skinned single fiber prepration and single fiber in vitro motility assay suggested that the mutation induced alteration in myosin-actin kinetics causing a reduced number of myosin molecules in the strong actin binding state, resulting in overall muscle weakness in the absence of muscle wasting. A study on a type IIa MyHC isoform missense mutation at the motor protein level demonstrated a significant negative effect on the function of the IIa MyHC isoform while other myosin isoforms had normal function. This provides evidence that the pathogenesis of the MyHC IIa E706K myopathy involves defective function of the mutated myosin as well as alterations in the structural integrity of all muscle irrespective of MyHC isoform expression.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 88 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 562
Keyword
Scaling, myosin heavy chain, in vitro motility assay, myopathy
National Category
Physiology
Research subject
Neuroscience
Identifiers
urn:nbn:se:uu:diva-123005 (URN)978-91-554-7812-4 (ISBN)
Public defence
2010-05-25, Enghoffssalen, Ing 50 Akademiska Sjukhuset, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2010-05-04 Created: 2010-04-22 Last updated: 2010-05-18

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