Meulemans Daniel, Bronner-Fraser Marianne
Division of Biology, 139-74, California Institute of Technology, Pasadena 91125, USA.
Development. 2002 Nov;129(21):4953-62. doi: 10.1242/dev.129.21.4953.
The neural crest is a uniquely vertebrate cell type present in the most basal vertebrates, but not in cephalochordates. We have studied differences in regulation of the neural crest marker AP-2 across two evolutionary transitions: invertebrate to vertebrate, and agnathan to gnathostome. Isolation and comparison of amphioxus, lamprey and axolotl AP-2 reveals its extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, implying co-option of AP-2 genes by neural crest cells early in vertebrate evolution. Expression in non-neural ectoderm is a conserved feature in amphioxus and vertebrates, suggesting an ancient role for AP-2 genes in this tissue. There is also common expression in subsets of ventrolateral neurons in the anterior neural tube, consistent with a primitive role in brain development. Comparison of AP-2 expression in axolotl and lamprey suggests an elaboration of cranial neural crest patterning in gnathostomes. However, migration of AP-2-expressing neural crest cells medial to the pharyngeal arch mesoderm appears to be a primitive feature retained in all vertebrates. Because AP-2 has essential roles in cranial neural crest differentiation and proliferation, the co-option of AP-2 by neural crest cells in the vertebrate lineage was a potentially crucial event in vertebrate evolution.
神经嵴是一种独特的脊椎动物细胞类型，存在于最原始的脊椎动物中，但在头索动物中不存在。我们研究了在两个进化转变过程中神经嵴标志物AP-2的调控差异：从无脊椎动物到脊椎动物，以及从无颌类到有颌类。文昌鱼、七鳃鳗和蝾螈AP-2的分离和比较显示，其在脊椎动物背神经管和咽弓中广泛扩展，这意味着在脊椎动物进化早期神经嵴细胞对AP-2基因的利用。在非神经外胚层中的表达是文昌鱼和脊椎动物的一个保守特征，表明AP-2基因在该组织中具有古老的作用。在前神经管腹外侧神经元亚群中也有共同表达，这与在脑发育中的原始作用一致。蝾螈和七鳃鳗中AP-2表达的比较表明，有颌类动物中颅神经嵴模式有所细化。然而，表达AP-2的神经嵴细胞向咽弓中胚层内侧迁移似乎是所有脊椎动物保留的一个原始特征。由于AP-2在颅神经嵴分化和增殖中具有重要作用，神经嵴细胞在脊椎动物谱系中对AP-2的利用可能是脊椎动物进化中的一个关键事件。
