Wnt signaling from the dorsal neural tube is required for the formation of the medial dermomyotome.
Signals originating from tissues surrounding somites are involved in mediolateral and dorsoventral patterning of somites and in the differentiation of the myotome. Wnt-1 and Wnt-3a, which encode members of the Wnt family of cystein-rich secreted signaling molecules, are coexpressed at the dorsal midline of the developing neural tube, an area adjacent to the dorsomedial portion of the somite. Several lines of evidence indicate that Wnt-1 and Wnt-3a have the ability to induce the development of the medial and dorsal portion of somites, as well as to induce myogenesis. To address whether these Wnt signalings are really essential for the development of somites during normal embryogenesis, we investigated the development of somites in mouse embryos lacking both Wnt-1 and Wnt-3a. Here we demonstrate that the medial compartment of the dermomyotome is not formed and the expression of a lateral dermomyotome marker gene, Sim-1, is expanded more medially in the absence of these Wnt signalings. In addition, the expression of a myogenic gene, Myf-5, is decreased at 9.5 days post coitum whereas the level of expression of a number of myogenic genes in the later stage appeared normal. These results indicate that Wnt-1 and Wnt-3a signalings actually regulate the formation of the medial compartment of the dermomyotome and the early part of myogenesis.
Ikeya
M
M
Center for Molecular and Developmental Biology, Faculty of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
Takada
S
S
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D019521:Body Patterning / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005314:Embryonic and Fetal Development; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D024510:Muscle Development; D009124:Muscle Proteins / Q000235:genetics; D018482:Muscle, Skeletal / Q000254:growth & development*; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D019170:Somites / Q000378:metabolism; D014157:Transcription Factors; D051153:Wnt Proteins; D051155:Wnt1 Protein; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D029961:Zebrafish Proteins
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D051155:Wnt1 Protein; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D029961:Zebrafish Proteins; C101750:Sim1 protein, mouse; C491092:Sim1a protein, zebrafish; C495246:Wnt1 protein, mouse; C555511:Wnt3a protein, mouse; C489412:pax3a protein, zebrafish; C068686:Pax3 protein, mouse