Fig. 7

Fig. 7

HB-EGF Activates a Wnt/β-Catenin-Signaling Cascade (A) β-Catenin immunofluorescence shows that HB-EGF stimulates β-catenin stabilization in proliferating progenitors of the uninjured retina. (B) In situ hybridization and BrdU immunofluorescence show that HB-EGF-dependent induction of transgene expression in TOP:dGFP Wnt-signaling reporter fish is inhibited by pyrvinium (Pyrvin) (arrows identify double-labeled gfp⁺/BrdU⁺ cells). (C and D) Pyrvinium (Pyrvin)-mediated inhibition of Wnt/β-catenin signaling suppresses HB-EGF-dependent generation of proliferating progenitors in the uninjured retina. Error bars represent SD. ^*p < 0.01. (E) RT-PCR shows that pyrvinium suppresses HB-EGF-dependent induction of regeneration-associated genes in the uninjured retina. (F) Ascl1a knockdown suppresses HB-EGF-dependent β-catenin stabilization and BrdU incorporation in the uninjured retina. Arrows identify β-catenin⁺ and BrdU⁺ cells in the control MO-treated retina, whereas arrowheads identify β-catenin⁺ and BrdU⁺ cells in the ascl1a MO-treated retina. (G) Summary of signaling cascades and genes regulated by HB-EGF. Scale bars, 50 μm.