Analysis of the Hoxa3 gene that regulates the migration/differentiation of the cranial neural crest cells.

在脊椎动物中，鳃神经的近端感觉神经节和远端感觉神经节分别来自神经脊细胞(NCC)和安慰剂。我们之前曾报道，在Hoxa3基因敲除的小鼠胚胎中，舌咽神经的NCC和胎盘来源的细胞在迁移过程中存在缺陷。在这篇报道中，为了解决Hoxa3在哪种细胞类型中的表达与上述表型有关的问题，我们用反义吗啉寡核苷酸(MO)特异性地在NCCs/神经管或鸡胚胎的胎盘细胞中阻断了该基因的表达。我们的结果表明，Hoxa3功能是鳃上胎盘细胞迁移所必需的，并且Hoxa3调节这些细胞在NCCs/神经管和胎盘细胞中的迁移。我们还发现，鸡和小鼠的Hoxa3表达在前脑，这原本被认为是一个HOX阴性区域。另外，Hoxa3突变的小鼠在咽弓动脉和甲状旁腺器官发生方面存在缺陷。我们检查了该区域神经脊的迁移和分化情况。我们的结果表明，在Hoxa3突变的小鼠胚胎中，神经脊细胞的初始迁移是正常的，但进一步的增殖和/或分化受到了影响。

In vertebrates, the proximal and distal sensory ganglia of the branchial nerves are derived from neural crest cells(NCCs) and placodes, respectively. We previously reported that in Hoxa3 knockout mouse embryos, NCCs and placode-derived cells of the glossopharyngeal nerve were defective in their migration. In this report, to address the question as to in which cell type is the expression of Hoxa3 responsible for the above phenotype, we blocked the expression of the gene with anti-sense morpholino oligonucleotides(MO) specifically in either NCCs/the neural tube or placodal cells of chicken embryos. Our results showed that Hoxa3 function is required for the migration of the epibranchial placode-derived cells and that Hoxa3 regulate these cell migration in both NCCs/the neural tube and placodal cells. We also found that chicken and mouse Hoxa3 are expressed in the anterior head, which had been originally thought to be a Hox-negative region.Also, in Hoxa3 mutant mice have defects in the pharyngeal arch artery and the parathyroid gland organogenesis. We have checked the migration and differentiation of the neural crest in this area. Our results indicate that the initial migration of the neural crest is normal but further proliferation and/or differentiation of the crest cells are affected in the Hoxa3 mutant mouse embryos.