Lnx-2b restricts gsc expression to the dorsal mesoderm by limiting Nodal and Bozozok activity.
Coordinated Nodal-related signals and Bozozok (Boz) activity are critical for the initial specification of dorsal mesoderm and anterior neuroectoderm during zebrafish embryogenesis. Overexpression of Boz expands gsc expression into the ventro-lateral marginal blastomeres where Nodal signaling is active, but is insufficient to induce ectopic gsc expression in the animal region. We found that overexpression of Boz together with depletion of Lnx-2b (previously named Lnx-like, Lnx-l), but not each manipulation alone, causes robust gsc expression in all blastomeres. Furthermore, nodal-related signals are required for gsc expression in embryos with elevated Boz activity. Through targeted injection into single cells at the 128-cell stage we illustrate the role of maternally deposited Lnx-2b to restrict the expansion of gsc expression into the presumptive ectodermal region. This report provides a novel mechanism for limiting dorsal organizer specification to a defined region of the early zebrafish embryo.
Laboratory of Molecular Genetics, Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Hyunju
H
Ro
Igor B
IB
Dawid
D000818:Animals; D004475:Ectoderm / Q000378:metabolism; D051956:Goosecoid Protein / Q000096:biosynthesis*; D018398:Homeodomain Proteins / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism*; D055456:Nodal Signaling Ligands / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*
D051956:Goosecoid Protein; D018398:Homeodomain Proteins; D055456:Nodal Signaling Ligands; D029961:Zebrafish Proteins; C113874:dharma protein, zebrafish; C497995:gsc protein, zebrafish; C485171:ndr1 protein, zebrafish; D044767:Ubiquitin-Protein Ligases; C554948:lnx2b protein, zebrafish