Ras-Mediated FGF Signaling Is Required for the Formation of Posterior but Not Anterior Neural Tissue in Xenopus laevis

• Published in: Developmental biology 2000-11, Vol.227 (1), p.183-196
• Main Authors: Ribisi, Stephen, Mariani, Francesca V., Aamar, Emil, Lamb, Teresa M., Frank, Dale, Harland, Richard M.
• Format: Article
• Language: English
• Subjects: Animals; Basic Helix-Loop-Helix Transcription Factors; Body Patterning; Carrier Proteins; Cell Lineage; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Ectoderm - metabolism; Ectoderm - transplantation; Embryonic Induction; Fetal Tissue Transplantation; Fibroblast Growth Factors - antagonists & inhibitors; Fibroblast Growth Factors - metabolism; Gastrula - cytology; Gastrula - metabolism; Genes, Dominant - genetics; HMGB Proteins; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Mitogen-Activated Protein Kinases - metabolism; Mutation - genetics; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Nervous System - cytology; Nervous System - embryology; Nervous System - metabolism; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Phosphorylation; Proteins - genetics; Proteins - metabolism; ras Proteins - genetics; ras Proteins - metabolism; Receptors, Fibroblast Growth Factor - antagonists & inhibitors; Receptors, Fibroblast Growth Factor - genetics; Receptors, Fibroblast Growth Factor - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Signal Transduction; SOXB1 Transcription Factors; Transcription Factors; Xenopus laevis; Xenopus laevis - embryology; Xenopus laevis - metabolism; Xenopus Proteins
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1006/dbio.2000.9889

Fibroblast growth factor (FGF) has been proposed to be involved in the specification and patterning of the developing vertebrate nervous system. There is conflicting evidence, however, concerning the requirement for FGF signaling in these processes. To provide insight into the signaling mechanisms that are important for neural induction and anterior–posterior neural patterning, we have employed the dominant negative Ras mutant, N17Ras, in addition to a truncated FGF receptor (XFD). Both N17Ras and XFD, when expressed in Xenopus laevis animal cap ectoderm, inhibit the ability of FGF to generate neural pattern. They also block induction of posterior neural tissue by XBF2 and XMeis3. However, neither XFD nor N17Ras inhibits noggin, neurogenin, or XBF2 induction of anterior neural markers. MAP kinase activation has been proposed to be necessary for neural induction, yet N17Ras inhibits the phosphorylation of MAP kinase that usually follows explantation of explants. In whole embryos, Ras-mediated FGF signaling is critical for the formation of posterior neural tissues but is dispensable for neural induction.