Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK, 73019, USA.
Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK, 73019, USA
Development. 2018 Jul 26;145(14):dev164780. doi: 10.1242/dev.164780.
The origin of the vertebrate head is one of the great unresolved issues in vertebrate evolutionary developmental biology. Although many of the novelties in the vertebrate head and pharynx derive from the neural crest, it is still unknown how early vertebrates patterned the neural crest within the ancestral body plan they inherited from invertebrate chordates. Here, using a basal vertebrate, the sea lamprey, we show that homologs of Semaphorin3F (Sema3F) ligand and its Neuropilin (Nrp) receptors show complementary and dynamic patterns of expression that correlate with key periods of neural crest development (migration and patterning of cranial neural crest-derived structures). Using CRISPR/Cas9-mediated mutagenesis, we demonstrate that lamprey Sema3F is essential for patterning of neural crest-derived melanocytes, cranial ganglia and the head skeleton, but is not required for neural crest migration or patterning of trunk neural crest derivatives. Based on comparisons with jawed vertebrates, our results suggest that the deployment of Nrp-Sema3F signaling, along with other intercellular guidance cues, was pivotal in allowing early vertebrates to organize and pattern cranial neural crest cells into many of the hallmark structures that define the vertebrate head.
脊椎动物头部的起源是脊椎动物进化发育生物学中尚未解决的重大问题之一。尽管脊椎动物头部和咽部的许多新特征源自神经嵴，但仍不清楚早期脊椎动物如何在从无脊椎脊索动物继承的祖先体式图中对神经嵴进行模式化。在这里，我们使用一种基础脊椎动物——海七鳃鳗，表明 Sema3F（Semaphorin3F）配体及其 Neuropilin（Nrp）受体的同源物表现出互补和动态的表达模式，与神经嵴发育的关键时期（颅神经嵴衍生结构的迁移和模式化）相关。使用 CRISPR/Cas9 介导的诱变，我们证明了七鳃鳗 Sema3F 对于神经嵴衍生的黑色素细胞、颅神经节和头部骨骼的模式化是必不可少的，但对于神经嵴迁移或躯干神经嵴衍生物的模式化是不需要的。基于与有颌脊椎动物的比较，我们的结果表明，Nrp-Sema3F 信号的部署以及其他细胞间导向线索，对于早期脊椎动物将颅神经嵴细胞组织并模式化为许多定义脊椎动物头部的标志性结构至关重要。
