Amphioxus and lamprey AP-2 genes: implications for neural crest evolution and migration patterns.

Area of Science:

• Evolutionary developmental biology
• Comparative genomics
• Vertebrate paleontology

Background:

• The neural crest is a defining vertebrate cell type absent in closely related invertebrate chordates.
• Understanding neural crest evolution requires examining gene regulation across key evolutionary transitions.

Purpose of the Study:

• To investigate the evolutionary history and regulation of the neural crest marker AP-2.
• To compare AP-2 gene regulation during the invertebrate-to-vertebrate and agnathan-to-gnathostome transitions.

Main Methods:

• Isolation and comparative analysis of AP-2 genes from amphioxus, lamprey, and axolotl.
• Expression pattern analysis of AP-2 in different vertebrate and invertebrate models.

Main Results:

• AP-2 shows extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, suggesting early co-option by neural crest cells.
• Conserved expression in non-neural ectoderm and anterior neural tube neurons indicates ancient roles for AP-2.
• Comparison between axolotl and lamprey suggests elaboration of cranial neural crest patterning in gnathostomes.

Conclusions:

• Co-option of AP-2 by neural crest cells was a critical event in vertebrate evolution.
• AP-2 plays essential roles in neural crest differentiation and proliferation.
• Specific migration patterns of AP-2-expressing neural crest cells are conserved across vertebrates.