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Rel directly activates a secreted Wnt antagonist Frzb to restrict Wnt/β-catenin-mediated dorsal organizer formation. a, b Rel positively regulates frzb expression. a qPCR analysis for expression of Wnt antagonists (frzb, sfrp1a, dkk1b and notum1a) in dome stage embryos injected with ctrl MO or rel MO. Normalized values are shown as means ± SEM. n = 3, biologically independent samples. P-values from unpaired two-tailed t-tests are indicated. b WISH for frzb in dome stage embryos injected with ctrl MO or rel MO, animal view. c, d Rel inhibits Wnt/β-catenin signaling through Frzb. WISH for (c) Wnt targets axin2 and sp5l; (d) dharma and chordin in embryos injected with ctrl MO, rel MO or rel MO with frzb mRNA at indicated stage, animal view. Box plots of the angle of marker genes show first and third quartile, median is represented by a line, whiskers indicate the minimum and maximum. Each dot represents one embryo. P-values from two-tailed one-way ANOVAs with Sidak correction are indicated. e, f Rel activates promoter of frzb. e Top panel shows the schematic diagram of the upstream region of zebrafish frzb gene. The NFκB-binding element possessing the strongest potential to bind to Rel homodimer is marked with red “pin” while others are marked by black “pins”. Gray and blue boxes indicate Exons and UTRs, respectively. Bottom panel shows the schematic diagrams of the reporter constructs, frzb:luc and frzb:luc MT. f FISH for luciferase (magenta) and gfp (green) in dome-stage embryos injected with pDha-GFP and frzb:luc or frzb:luc MT, with MOs as indicated, animal view. Scale bar = 200 μm. Source data are provided as a Source Data file.
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