Xenbase Image ID: 23491

Figure 6. FGF8 Neural Crest Inducing Properties Requires Msx1 Activity(A) Msx1 exhibits a strong response to FGF8 overexpression (50 pg) and is broadly activated on the injected side, including lateral and ventral areas of the embryo (a). The FGF8-AMO (40 ng) abolishes Msx1 expression (b). FGF8 overexpression does not increase the level of Pax3 expression but, rather, expands the Pax3 domain (c). FGF8-MO decreases Pax3 expression partially on the injected side (d).(B) Fgf8 mRNA injections (125–250 pg) either alone or with the control MO expanded greatly Slug expression around the neural plate (c). At this dose, Pax3 expression also encompassed the ANF (a). In the presence of Msx1 MO, FGF8 induction of Slug is abolished (d), whereas Pax3 remains as with control (b). Pax3-MO also blocks Slug activation by FGF8 in vivo.(C) FGF8MO does not affect global patterning of the neural plate as shown by the mild shift in Krox20 expression by rhombomeres three and five but, rather, prevents NC induction as seen by the loss of rhombomere five NC (arrows).(D) Msx1 overexpression rescued the loss of FGF8 activity, showing that Msx1 mediates FGF8 activity. Both Slug (stage 19 tailbud) and Twist (stage 35 tadpoles) are efficiently rescued both in cephalic NC (individual streams are rescued) and trunk NC.(E) Model part 3: FGF8 controls Msx1 expression in vivo independently of WNTs, but FGF8 depends on both Msx1 and Pax3 for inducing Slug. Image published in: Monsoro-Burq AH et al. (2005) Copyright © 2005. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

Return to previous page