XB-IMG-23916
Xenbase Image ID: 23916
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Fig. 1. Signaling pathways and transcriptional factors involved in the regulation of Hairy2 expression in NC. (A) Hairy2 is activated by attenuation of BMP (tBr 50 pg), activation of Wnt (dnGSK3β 250 pg) or FGF (FGF8a 25 pg). Respective induction: (a) 72% n = 27; (b) 50% n = 25; (c) 64% n = 22. Activation of BMP (Ca-Alk3 50 pg), inhibition of Wnt (GSK3β 250 pg) or FGF (δR4 250 pg) has the opposite effect. Respective inhibition: (d) 82% n = 31; (e) 58% n = 17; (f) 62% n = 19. Activation (Su(H)Ank-GR 1 ng) or repression (Su(H)DBM-GR 1 ng) of Notch signaling does not influence Hairy2 expression (g, h; unaffected 92% n = 26 and 85% n = 4, respectively). (i) Q-PCR analysis of animal cap explants derived from embryos injected radially with ICD (250 pg) or Su(H)dbm (250 pg) mRNA together with noggin (50 pg)+ Wnt8 (50 pg) mRNA. (B) Expression of Hairy2 in Msx-1 (a, b), Pax3 (c, d), and Zic1 (e, f) overexpressing or depleted (20 ng MO) embryos. Overexpression of each of these factors (125–250 pg mRNA) expands Hairy2 expression (Respective induction: (a) 57%, n = 77; (c) 63%, n = 30; (e), 85% n = 55). Depletion of Msx1 reduces Hairy2 expression on the injected side (b, 49% with mild decrease, n = 70). Depletion of Pax3 (d) and Zic1 (f) inhibited Hairy2 expression (respective inhibition: d, 63% n = 59; f, 65%, n = 29). (C) FGF8a injections with CoMO expanded Hairy2 (a) and Snail2 (e) (Expansion in 92%, n = 49 and 55%, n = 20 respectively). In presence of Msx1 MO, the expansion caused by activation of FGF signaling was still observed for Hairy2 (b, 73% expanded, n = 30) but not for Snail2 (f, 45% decreased, n = 20). Activation of Wnt signaling by Wnt7b with CoMO expands Hairy2 (c, 83% expanded, n = 18) and Snail2 (g, 78% of expansion, n = 17). In the presence of Pax3 MO, Wnt7b still expanded Hairy2 expression (d, 93% expansion, n = 14) while Snail2 is decreased (h, 62% reduced, n = 13). All embryos are shown in dorso-anterior view. β-galactosidase was used as a lineage tracer (light blue staining) and the injected side is oriented to the right. (D) NC inducing signals and neural border factors involved in Hairy2 regulation. The dashed line indicates that Msx1 contributes to a lesser extend than Pax3 and Zic1 to Hairy2 expression. Image published in: Nichane M et al. (2008) Copyright © 2008. Image reproduced with permission of the Publisher, Elsevier B. V.
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