Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038379 (strabismus)
 9,317 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The zebrafish bozozok (boz) gene encoding a homeodomain protein (also named Dharma/Nieuwkoid) is required during blastula stages for the formation of a complete Spemann-Mangold gastrula organizer and subsequent development of axial mesoderm and anterior neural structures. Expression of bozin the dorsal yolk syncytial layer (YSL) and overlying marginal blastomeres is activated by beta-catenin. Bozozok itself acts as a transcriptional repressor, and promotes organizer formation by directly inhibiting expression of the bmp2b (swirl) gene and by negatively regulating Wnt signaling by an unknown mechanism. boz cooperates with the Nodal-related secreted factors, Cyclops and Squint, in organizer formation. The incomplete organizer in boz mutants is deficient in expression of a number of factors such as Chordin that antagonize Bone morphogenetic proteins (Bmps), and Dickkopf 1, a Wnt antagonist. Conversely, the dorsal blastoderm of boz mutants exhibits ectopic expression of genes normally excluded from the dorsal midline such as wnt8 or tbx6. boz specifies the formation of anterior neuroectoderm by regulating Bmp and Wnt pathways in a fashion consistent with Nieuwkoop's two-step neural patterning model. boz promotes neural induction by limiting the anti-neuralizing activity of Bmp morphogens. In addition, by negative regulation of Wnt signaling, boz limits posteriorization of neuroectoderm. bozozok chordino double mutants exhibit a synergistic loss of head and trunk. This synthetic phenotype is due to dramatically increased Bmp signaling and consequent massive accumulation of cells in the tailbud at the expense of dorso-anterior structures. Therefore, boz and din act in overlapping pathways that provide the main mechanism to limit Bmp signaling in the zebrafish gastrula and allow for head and trunk development. Notably, Bozozok appears to function by repressing transcription of target genes such as swr (bmp2b) gene, and as such is the earliest acting repressor that the nascent dorsal axis is using to antagonize ventral influences.
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PMID:The role of the homeodomain protein Bozozok in zebrafish axis formation. 1129 60

We have used the maternal effect mutant ichabod, which is deficient in maternal beta-catenin signaling, to test for the epistatic relationship between beta-catenin activation, FGF signaling and bozozok, squint and chordin expression. Injection of beta-catenin RNA into ichabod embryos can completely rescue normal development. By contrast, when FGF signaling is inhibited, beta-catenin did not induce goosecoid and chordin, repress bmp4 expression or induce a dorsal axis. These results demonstrate that FGF signaling is necessary for beta-catenin induction of the zebrafish organizer. We show that FGFs function downstream of squint and bozozok to turn on chordin expression. Full rescue of ichabod by Squint is dependent on FGF signaling, and partial rescue by FGFs is completely dependent on chordin. By contrast, Bozozok can rescue the complete anteroposterior axis, but not notochord, in embryos blocked in FGF signaling. Surprisingly, accumulation of bozozok transcript in beta-catenin RNA-injected ichabod embryos is also dependent on FGF signaling, indicating a role of FGFs in maintenance of bozozok RNA. These experiments show that FGF-dependent organizer function operates through both bozozok RNA accumulation and a pathway consisting of beta-catenin-->Squint-->FGF-->Chordin, in which each component is sufficient for expression of the downstream factors of the pathway, and in which Nodal signaling is required for FGF gene expression and FGF signaling is required for Squint induction of chordin.
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PMID:FGF signaling is required for {beta}-catenin-mediated induction of the zebrafish organizer. 1687 84