ArticleBMC developmental biology2007
A role for Insulin-like growth factor 2 in specification of the fast skeletal muscle fibre.
Article in BMC developmental biology, 2007. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 12 papers.
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12 citing papers in PubMed, 20 citations in OpenAlex.
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- Tbx15 controls skeletal muscle fibre-type determination and muscle metabolism.Nature communications · 2015Article
- Improvement of contraction force in injured skeletal muscle after autologous mesenchymal stroma cell transplantation is accompanied by slow to fast fiber type shift.Transfusion medicine and hemotherapy : offizielles Organ der Deutschen Gesellschaft fur Transfusionsmedizin und Immunhamatologie · 2013Article
- The imprinted H19 lncRNA antagonizes let-7 microRNAs.Molecular cell · 2013Article
- Myod and H19-Igf2 locus interactions are required for diaphragm formation in the mouse.Development (Cambridge, England) · 2013Article
- Maternal and paternal genomes differentially affect myofibre characteristics and muscle weights of bovine fetuses at midgestation.PloS one · 2013Article
- Adult and embryonic skeletal muscle microexplant culture and isolation of skeletal muscle stem cells.Journal of visualized experiments : JoVE · 2010Article
- Muscle development and obesity: Is there a relationship?Organogenesis · 2008Article
- Muscular dystrophy begins early in embryonic development deriving from stem cell loss and disrupted skeletal muscle formation.Disease models & mechanismsArticle
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4 authors at 3 institutions in 2 countries.
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Abstract
backgroundFibre type specification is a poorly understood process beginning in embryogenesis in which skeletal muscle myotubes switch myosin-type to establish fast, slow and mixed fibre muscle groups with distinct function. Growth factors are required to establish slow fibres; it is unknown how fast twitch fibres are specified. Igf-2 is an embryonically expressed growth factor with established in vitro roles in skeletal muscle. Its localisation and role in embryonic muscle differentiation had not been established.
resultsBetween E11.5 and E15.5 fast Myosin (FMyHC) localises to secondary myotubes evenly distributed throughout the embryonic musculature and gradually increasing in number so that by E15.5 around half contain FMyHC. The Igf-2 pattern closely correlates with FMyHC from E13.5 and peaks at E15.5 when over 90% of FMyHC+ myotubes also contain Igf-2. Igf-2 lags FMyHC and it is absent from muscle myotubes until E13.5. Igf-2 strongly down-regulates by E17.5. A striking feature of the FMyHC pattern is its increased heterogeneity and attenuation in many fibres from E15.5 to day one after birth (P1). Transgenic mice (MIG) which express Igf-2 in all of their myotubes, have increased FMyHC staining, a higher proportion of FMyHC+ myotubes and loose their FMyHC staining heterogeneity. In Igf-2 deficient mice (MatDi) FMyHC+ myotubes are reduced to 60% of WT by E15.5. In vitro, MIG induces a 50% excess of FMyHC+ and a 30% reduction of SMHyC+ myotubes in C2 cells which can be reversed by Igf-2-targeted ShRNA resulting in 50% reduction of FMyHC. Total number of myotubes was not affected.
conclusionIn WT embryos the appearance of Igf-2 in embryonic myotubes lags FMyHC, but by E15.5 around 45% of secondary myotubes contain both proteins. Forced expression of Igf-2 into all myotubes causes an excess, and absence of Igf-2 suppresses, the FMyHC+ myotube component in both embryonic muscle and differentiated myoblasts. Igf-2 is thus required, not for initiating secondary myotube differentiation, but for establishing the correct proportion of FMyHC+ myotubes during fibre type specification (E15.5-P1). Since specific loss of FMyHC fibres is associated with many skeletal muscle pathologies these data have important medical implications.
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