Résumé :
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The extracellular matrix acts as a structural support for muscle fibers and is essential for muscle function. Collagen XV is a component of basement membrane zone, mainly expressed in skeletal muscle. No mutation in the human gene has been identified yet, but Col15a-/- mice presented a skeletal myopathy1. To detail the role of this collagen in muscle development and the underlying mechanism, we used the zebrafish model. Two paralogs in the zebrafish genome, named col15a1a and col15a1b have been identified. We previously reported that col15a1a expression is restricted to notochord2 while col15a1b is transiently expressed during morphogenesis by adaxial cells, the slow fiber precursors3. We now show that col15a1b expression in these cells is dependent on the Sonic hedgehog pathway and that the protein is deposited in the medial surface of the somite. Morpholino knock-down of col15a1b results in slow fiber defects and abnormal myogenesis. Lack of col15a1b also disturbs primary motoneuron migration that could explain the global myotome alteration observed at later stages. These data provide new insights into the role of this collagen in neuro-muscular development. 1. Eklund et al, 2001, PNAS, 98 :1194-9. 2. Pagnon-Minot et al, 2008, Biol Dev, 316:21-35. 3. Bretaud et al, 2011, GEP, 11:129-34
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