title: FGF4 regulates blood and muscle specification in Xenopus laevis.
abstract: BACKGROUND
  FGF (fibroblast growth factor) signalling is known to be required for many aspects of mesoderm formation and patterning during Xenopus development and has been implicated in regulating genes required for the specification of both blood and skeletal muscle lineages.
  
  
  RESULTS
  In the present study, we have specifically knocked down the expression of FGF4 using AMO (antisense morpholino oligonucleotide)-mediated inhibition and demonstrate that FGF4 acts in the dorsal marginal zone to restrict blood development and promote the development of skeletal muscle. In addition, we used a drug inhibitor of FGF signalling and an inducible form of FGFR1 (FGF receptor 1) to identify a period of competence during late blastula and gastrula stages when FGF signalling acts to regulate blood versus muscle specification. Notably, we found that it is the dorsal activity of FGF that is required to restrict the expression of SCL (stem cell leukaemia) to the ventral blood island.
  
  
  CONCLUSIONS
  Our data indicate that FGF4 is a key organizer-derived signal involved in the process of dorsoventral patterning of the mesoderm.
authors.affiliation: Area 11, Department of Biology, University of York, York YO10 5YW, U.K.
authors.forename: Harry V
authors.initials: HV
authors.lastname: Isaacs
authors.forename: Anne E
authors.initials: AE
authors.lastname: Deconinck
authors.forename: Mary E
authors.initials: ME
authors.lastname: Pownall
mesh_terms: D000818:Animals; D036703:Blastula / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001773:Blood Cells / Q000166:cytology / Q000378:metabolism*; D019521:Body Patterning / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D004625:Embryo, Nonmammalian; D051519:Fibroblast Growth Factor 4 / Q000235:genetics / Q000378:metabolism*; D005775:Gastrula / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014982:Xenopus laevis / Q000196:embryology* / Q000378:metabolism
chemical_list: D051519:Fibroblast Growth Factor 4; D016376:Oligonucleotides, Antisense; D051496:Receptor, Fibroblast Growth Factor, Type 1