Snail2 controls mesodermal BMP/Wnt induction of neural crest.

Area of Science:

• Developmental biology
• Molecular biology
• Vertebrate embryogenesis

Background:

• The neural crest, unique to vertebrates, is an induced tissue essential for development.
• Neural crest induction in Xenopus laevis relies on signals from the dorsolateral mesodermal zone during gastrulation.
• Transcription factors Snail2, Snail1, and Twist1 are expressed in this signaling region and known to be involved in mesoderm and neural crest formation.

Purpose of the Study:

• To investigate the specific roles of Snail1, Snail2, and Twist1 in mesoderm and neural crest formation in Xenopus laevis.
• To elucidate the mechanisms by which Snail2 regulates neural crest induction, particularly its interaction with mesodermal signals.

Main Methods:

• Targeted blastomere injection in Xenopus laevis embryos.
• Morpholino-based loss-of-function experiments.
• Explant studies to analyze cell signaling and gene expression.
• Rescue experiments using bmp4 and wnt8 RNA.

Main Results:

• Snail1 is also required for mesoderm and neural crest formation.
• Loss of snail1, snail2, or twist1 function in specific embryonic lineages blocks mesoderm formation, but only snail2 loss abrogates neural crest.
• Snail2's role in neural crest loss involves mesoderm-derived factors and can be rescued by bmp4 and wnt8.
• Snail2 activity loss alters RNA levels of BMP and Wnt signaling pathway components.

Conclusions:

• Snail1, Snail2, and Twist1 are essential for mesoderm formation.
• Snail2 is uniquely required for neural crest induction, independent of its role in mesoderm formation.
• Snail2 acts as a key regulator of mesoderm-derived signals that induce the neural crest.