title: Zebrafish slow muscle cell migration induces a wave of fast muscle morphogenesis.
abstract: The specification and morphogenesis of slow and fast twitch muscle fibers are crucial for muscle development. In zebrafish, Hedgehog is required for slow muscle fiber specification. However, less is known about signals that promote development of fast muscle fibers, which constitute the majority of somitic cells. We show that when Hedgehog signaling is blocked, fast muscle cell elongation is disrupted. Using genetic mosaics, we show that Hedgehog signal perception is required by slow muscle cells but not by fast muscle cells for fast muscle cell elongation. Furthermore, we show that slow muscle cells are sufficient to pattern the medial to lateral wave of fast muscle fiber morphogenesis even when fast muscle cells cannot perceive the Hedgehog signal. Thus, the medial to lateral migration of slow muscle fibers through the somite creates a morphogenetic signal that patterns fast muscle fiber elongation in its wake.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 USA.
authors.forename: Clarissa A
authors.initials: CA
authors.lastname: Henry
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Amacher
mesh_terms: D000818:Animals; D002465:Cell Movement; D005838:Genotype; D053823:Hedgehog Proteins; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009024:Morphogenesis; D024510:Muscle Development; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology*; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology*; D015398:Signal Transduction; D013997:Time Factors; D015534:Trans-Activators / Q000502:physiology; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D053823:Hedgehog Proteins; D015534:Trans-Activators; D029961:Zebrafish Proteins