Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK.
Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
Development. 2019 Nov 21;146(22):dev171405. doi: 10.1242/dev.171405.
The embryonic development of the pineal organ, a neuroendocrine gland on top of the diencephalon, remains enigmatic. Classic fate-mapping studies suggested that pineal progenitors originate from the lateral border of the anterior neural plate. We show here, using gene expression and fate mapping/lineage tracing in zebrafish, that pineal progenitors originate, at least in part, from the non-neural ectoderm. Gene expression in chick indicates that this non-neural origin of pineal progenitors is conserved in amniotes. Genetic repression of placodal, but not neural crest, cell fate results in pineal hypoplasia in zebrafish, while mis-expression of transcription factors known to specify placodal identity during gastrulation promotes the formation of ectopic pineal progenitors. We also demonstrate that fibroblast growth factors (FGFs) position the pineal progenitor domain within the non-neural border by repressing pineal fate and that the Otx transcription factors promote pinealogenesis by inhibiting this FGF activity. The non-neural origin of the pineal organ reveals an underlying similarity in the formation of the pineal and pituitary glands, and suggests that all CNS neuroendocrine organs may require a non-neural contribution to form neurosecretory cells.
松果体器官的胚胎发育仍然是一个谜，松果体器官是位于间脑顶部的神经内分泌腺。经典的命运图谱研究表明，松果体细胞起源于前神经板的外侧边界。我们在这里使用斑马鱼中的基因表达和命运图谱/谱系追踪研究表明，松果体细胞的起源至少部分来自非神经外胚层。鸡胚中的基因表达表明，这种松果体细胞的非神经起源在羊膜动物中是保守的。在斑马鱼中，抑制颅嵴细胞而不是神经嵴细胞的命运会导致松果体发育不全，而在原肠胚形成过程中指定颅嵴身份的转录因子的异位表达会促进异位松果体细胞的形成。我们还证明，成纤维细胞生长因子（FGFs）通过抑制松果体命运来定位非神经边界内的松果体细胞域，而 Otx 转录因子通过抑制这种 FGF 活性来促进松果体发生。松果体器官的非神经起源揭示了松果体和垂体形成的潜在相似性，并表明所有中枢神经系统神经内分泌器官的形成可能都需要非神经贡献来形成神经分泌细胞。
