Marín F, Charnay P
Unité 368 de l'Institut National de la Santé et de la Recherche Médicale, Ecole Normale Supérieure, 75230 Paris Cedex 05, France.
Development. 2000 Nov;127(22):4925-35. doi: 10.1242/dev.127.22.4925.
Krox20 and mafB/kr are regulatory genes involved in hindbrain segmentation and anteroposterior (AP) patterning. They are expressed in rhombomeres (r) r3/r5 and r5/r6 respectively, as well as in the r5/r6 neural crest. Since several members of the fibroblast growth factor (FGF) family are expressed in the otic/preotic region (r2-r6), we investigated their possible involvement in the regulation of Krox20 and mafB/kr. Application of exogenous FGFs to the neural tube of 4- to 7-somite chick embryos led to ectopic expression in the neural crest of the somitic hindbrain (r7 and r8) and to the extension of the Krox20- or mafB/kr-positive areas in the neuroepithelium. Application of an inhibitor of FGF signalling led to severe and specific downregulation of Krox20 and mafB/kr in the hindbrain neuroepithelium and neural crest. These data indicate that FGFs are involved in the control of regional induction and/or maintenance of Krox20 and mafB/kr expression, thus identifying a novel function for these factors in hindbrain development, besides their proposed more general role in early neural caudalisation.
Krox20和mafB/kr是参与后脑分割和前后轴（AP）模式形成的调控基因。它们分别在菱脑节（r）r3/r5和r5/r6以及r5/r6神经嵴中表达。由于成纤维细胞生长因子（FGF）家族的几个成员在耳/耳前区域（r2 - r6）表达，我们研究了它们可能参与对Krox20和mafB/kr的调控。将外源性FGF应用于4至7体节鸡胚的神经管，导致体节后脑（r7和r8）神经嵴中的异位表达，并使神经上皮中Krox20或mafB/kr阳性区域扩展。应用FGF信号抑制剂导致后脑神经上皮和神经嵴中Krox20和mafB/kr严重且特异性下调。这些数据表明FGF参与了Krox20和mafB/kr表达的区域诱导和/或维持的控制，从而确定了这些因子在后脑发育中的新功能，除了它们在早期神经尾化中所提出的更普遍作用之外。
