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Fig. 3. Regulation of Sox10 expression in the neural crest-forming region. (A) Regulation of Sox10 and Slug expression by Wnt signaling. Injection of Xwnt-1 plasmid (100 pg) expands Slug (79%, n = 53) and Sox10 (82%, n = 50) expression domains. Conversely, overexpression of GSK3 beta (1 ng), known to block Wnt signaling, prevents Slug (81%, n = 42) and Sox10 (65%, n = 51) expression on the injected side. (B) Sox9 and Slug are required for Sox10 expression. Sox9-AS injection (10 ng) blocks Slug (89%, n = 35) and Sox10 (96%, n = 54) expression. Similarly, a dominant negative Slug (delta Slug, 1 ng) blocks Slug (61%, n = 51) and Sox10 (56%, n = 50) expression. (C) Sox9 and Slug overexpression upregulate Sox10 expression. Sox9 (1 ng) overexpression leads to a limited expansion of Slug (83%, n = 58) and Sox10 (96%, n = 79) expression domains. Overexpression of Slug (0.1 ng) results in a robust expansion of Slug (90%, n = 30) and Sox10 (98%, n = 44). In all panels, early neurula stage embryos are viewed from the dorsal side, anterior to top. RNA encoding the lineage tracer beta-galactosidase was coinjected to identify the injected side (red staining), the right side in all panels. |