Ectodermal Wnt-6 promotes Myf5-dependent avian limb myogenesis

Dev Biol. 2005 Dec 1;288(1):221-33. doi: 10.1016/j.ydbio.2005.09.035. Epub 2005 Nov 2.

Abstract

Limb muscles of vertebrates are derived from precursor cells that migrate from the lateral edge of the dermomyotome into the limb bud. Although several signaling molecules have been reported to be involved in the process of limb myogenesis, none of their activities has led to a consolidate idea about the limb myogenic pathway. Particularly, the role of ectodermal signals in limb myogenesis is still obscure. Here, we investigated the role of the ectoderm and ectodermal Wnt-6 during limb muscle development. We found that ectopic expression of Wnt-6 in the limb bud specifically extends the expression domains of Pax3, Paraxis, Myf5, Myogenin, Desmin and Myosin heavy chain (MyHC) but inhibits MyoD expression. Ectoderm removal results in a loss of expression of all of these myogenic markers. We show that Wnt-6 can compensate the absence of the ectoderm by rescuing the expression of Pax3, Paraxis, Myf5, Myogenin, Desmin and MyHC but not MyoD. These results show that, in chick, at least two signals from the limb ectoderm are necessary for muscle development. One of the signals is Wnt-6, which plays a unique role in promoting limb myogenesis via Pax3/Paraxis-Myf5, whereas the other putative signaling pathway involving MyoD expression is negatively regulated by Wnt-6 signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avian Proteins / physiology*
  • Basic Helix-Loop-Helix Transcription Factors / physiology
  • Chick Embryo
  • Ectoderm / physiology*
  • Extremities / embryology*
  • Muscle Cells / physiology
  • Muscle Development / physiology*
  • Myogenic Regulatory Factor 5 / physiology*
  • PAX3 Transcription Factor
  • Paired Box Transcription Factors / physiology
  • Proto-Oncogene Proteins / physiology*
  • Signal Transduction / physiology*
  • Wnt Proteins / physiology*

Substances

  • Avian Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • Myogenic Regulatory Factor 5
  • PAX3 Transcription Factor
  • PAX3 protein, human
  • Paired Box Transcription Factors
  • Proto-Oncogene Proteins
  • Wnt Proteins
  • Wnt6 protein, mouse