Fgf8 drives myogenic progression of a novel lateral fast muscle fibre population in zebrafish.
Fibroblast growth factors (Fgfs) have long been implicated in regulating vertebrate skeletal muscle differentiation, but their precise role(s) in vivo remain unclear. Here, we show that Fgf8 signalling in the somite is required for myod expression and terminal differentiation of a subset of fast muscle cells in the zebrafish lateral somite. In the absence of Fgf8, lateral somite cells transiently express myf5 but fail to make muscle and remain in a dermomyotome-like state characterised by pax3 and meox expression. Slow muscle fibres form and commence normal migration in the absence of Fgf8, but fail to traverse the expanded undifferentiated lateral somite. The Fgf8-independent residual population of medial fast muscle fibres is not Hedgehog dependent. However, Fgf8-independent medial fast muscle precursors are lacking in floatinghead mutants, suggesting that they require another ventral midline-derived signal. We conclude that Fgf8 drives terminal differentiation of a specific population of lateral muscle precursor cells within the early somite.
Groves
Julie A
JA
MRC Centre for Developmental Neurobiology and Randall Division for Cell and Molecular Biophysics, New Hunt's House, King's College London, London SE1 1UL, UK.
Hammond
Christina L
CL
Hughes
Simon M
SM
D000818:Animals; D019521:Body Patterning / Q000502:physiology; D002454:Cell Differentiation; D004625:Embryo, Nonmammalian / Q000378:metabolism; D051524:Fibroblast Growth Factor 8 / Q000502:physiology*; D053823:Hedgehog Proteins; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology / Q000502:physiology*; D017570:MyoD Protein / Q000096:biosynthesis; D032446:Myoblasts / Q000378:metabolism / Q000502:physiology*; D051787:Myogenic Regulatory Factor 5 / Q000096:biosynthesis; D018008:Myogenin / Q000378:metabolism; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000096:biosynthesis; D015398:Signal Transduction; D019170:Somites / Q000502:physiology*; D015534:Trans-Activators / Q000502:physiology; D015027:Zebrafish / Q000196:embryology / Q000502:physiology*; D029961:Zebrafish Proteins / Q000096:biosynthesis
D053823:Hedgehog Proteins; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D018008:Myogenin; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D015534:Trans-Activators; D029961:Zebrafish Proteins; C489412:pax3a protein, zebrafish; D051524:Fibroblast Growth Factor 8