Beta catenin-independent activation of MyoD in presomitic mesoderm requires PKC and depends on Pax3 transcriptional activity.
Early activation of myogenesis in the somite depends on signals from surrounding tissues. Canonical beta-catenin dependent Wnt signalling preferentially activates Myf5. We now show, in explant experiments with presomitic mesoderm, that the expression of another myogenic determination factor, MyoD, depends on non-canonical Wnt signalling, probably emanating from the dorsal ectoderm. Inhibitors of PKC block MyoD expression, indicating that the intracellular Wnt pathway depends on this kinase. In the absence of Myf5 and Mrf4, this activation is only minorily affected and we identify Pax3 as the transcriptional mediator responsible for MyoD expression. When embryos expressing a constitutively active form of Pax3, PAX3-FKHR, are used for these studies in the presence of PKC inhibitors, MyoD expression is not affected, suggesting that Wnt signalling acts on the transcriptional activity of Pax3.
Brunelli
Silvia
S
Stem Cell Research Institute, H. San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy.
Relaix
Frederic
F
Baesso
Silvia
S
Buckingham
Margaret
M
Cossu
Giulio
G
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D017570:MyoD Protein / Q000378:metabolism*; D009924:Organ Culture Techniques; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D019170:Somites / Q000166:cytology / Q000378:metabolism; D015533:Transcriptional Activation; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000502:physiology*
D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; C068686:Pax3 protein, mouse; D011493:Protein Kinase C