title: Alterations at the cross-bridge level are associated with a paradoxical gain of muscle function in vivo in a mouse model of nemaline myopathy.
abstract: Nemaline myopathy is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. The first disease causing mutation (Met9Arg) was identified in the gene encoding α-tropomyosin slow gene (TPM3). Considering the conflicting findings of the previous studies on the transgenic (Tg) mice carrying the TPM3Met9Arg mutation, we investigated carefully the effect of the Met9Arg mutation in 8-9 month-old Tg(TPM3)Met9Arg mice on muscle function using a multiscale methodological approach including skinned muscle fibers analysis and in vivo investigations by magnetic resonance imaging and 31-phosphorus magnetic resonance spectroscopy. While in vitro maximal force production was reduced in Tg(TPM3)Met9Arg mice as compared to controls, in vivo measurements revealed an improved mechanical performance in the transgenic mice as compared to the former. The reduced in vitro muscle force might be related to alterations occurring at the cross-bridges level with muscle-specific underlying mechanisms. In vivo muscle improvement was not associated with any changes in either muscle volume or energy metabolism. Our findings indicate that TPM3(Met9Arg) mutation leads to a mild muscle weakness in vitro related to an alteration at the cross-bridges level and a paradoxical gain of muscle function in vivo. These results clearly point out that in vitro alterations are muscle-dependent and do not necessarily translate into similar changes in vivo.
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Gineste
authors.affiliation: Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Coen
authors.initials: C
authors.lastname: Ottenheijm
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Fur
authors.affiliation: Institut de Recherche Biomédicale des Armées, Physiologie des activités physiques, Brétigny sur Orge, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Banzet
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Pecchi
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Vilmen
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Cozzone
authors.affiliation: Institut de Recherche Biomédicale des Armées, Physiologie des activités physiques, Brétigny sur Orge, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Koulmann
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Edna C
authors.initials: EC
authors.lastname: Hardeman
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: David
authors.initials: D
authors.lastname: Bendahan
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Gondin
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D004734:Energy Metabolism; D008279:Magnetic Resonance Imaging; D051379:Mice; D008822:Mice, Transgenic; D018908:Muscle Weakness / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D009154:Mutation; D017696:Myopathies, Nemaline / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D014335:Tropomyosin / Q000235:genetics*; D019210:Troponin I / Q000378:metabolism
chemical_list: C411923:Tpm3 protein, mouse; D014335:Tropomyosin; D019210:Troponin I; D000255:Adenosine Triphosphate