title: Notch signaling regulates midline cell specification and proliferation in zebrafish.
abstract: Notochord and floor plate cells are sources of molecules that pattern tissues near the midline, including the spinal cord. Hypochord cells are also found at the midline of anamniote embryos and are important for aorta development. Delta-Notch signaling regulates midline patterning in the dorsal organizer by inhibiting notochord formation and promoting hypochord and possibly floor plate development, but the precise mechanisms by which this regulation occurs are unknown. We demonstrate here that floor plate and hypochord cells arise from distinct regions of the zebrafish shield. Blocking Notch signaling during gastrulation entirely prevented hypochord specification but only reduced the number of floor plate cells that developed compared to control embryos. In contrast, elevation of Notch signaling at the beginning of gastrulation caused expansion of hypochord at the expense of notochord, but floor plate was not affected. A cell proliferation assay revealed that Notch signaling maintains dividing floor plate progenitors. Together, our results indicate that Notch signaling regulates allocation of appropriate numbers of different midline cells by different mechanisms.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, U7211 BSB/MRBIII, 465 21st Avenue South, Nashville, TN 37232, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Latimer
authors.forename: Bruce
authors.initials: B
authors.lastname: Appel
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning; D002454:Cell Differentiation; D049109:Cell Proliferation; D004625:Embryo, Nonmammalian; D005326:Fetal Proteins; D005775:Gastrula / Q000378:metabolism / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D008954:Models, Biological; D009672:Notochord / Q000196:embryology; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction; D013234:Stem Cells / Q000502:physiology; D020825:T-Box Domain Proteins / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism / Q000502:physiology; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000098908:Brachyury Protein
chemical_list: D005326:Fetal Proteins; D051880:Receptors, Notch; D020825:T-Box Domain Proteins; D029961:Zebrafish Proteins; D000098908:Brachyury Protein