Ruiz i Altaba A, Placzek M, Baldassare M, Dodd J, Jessell T M
Howard Hughes Medical Institute, Columbia University, New York, New York 10032, USA.
Dev Biol. 1995 Aug;170(2):299-313. doi: 10.1006/dbio.1995.1216.
We have cloned a cDNA encoding the chick HNF-3 beta gene and have used RNA and antibody probes that detect HNF-3 beta to monitor the normal and induced expression of the gene in early embryos. HNF-3 beta expressed in Koller's sickle, at the onset of primitive streak formation, and later in Hensen's node. At neural plate and neural tube stages, HNF-3 beta is expressed transiently in the notochord and is then expressed by floor plate cells. Prospective floor plate cells that are located in the epiblast immediately anterior to Hensen's node prior to its regression do not express HNF-3 beta, providing evidence that floor plate fate is normally determined only after these cells populate the midline of the neural plate and overlie the notochord. Removal of the notochord in vivo prevents floor plate development and in this condition HNF-3 beta is not expressed by cells at the ventral midline of the neural tube. Notochord grafts induce ectopic floor plate development and ectopic neural expression of HNF-3 beta. In vitro, neural plate explants are induced to express HNF-3 beta by notochord cells in a contact-dependent but cycloheximide-resistant manner, providing evidence that expression of HNF-3 beta is a direct response of neural plate cells to notochord-derived inducing signals.
我们克隆了编码鸡HNF-3β基因的cDNA，并使用能检测HNF-3β的RNA和抗体探针来监测该基因在早期胚胎中的正常表达和诱导表达情况。HNF-3β在科勒镰刀区表达，在原条形成开始时表达，随后在亨森结中表达。在神经板和神经管阶段，HNF-3β在脊索中短暂表达，然后由底板细胞表达。在亨森结退化之前位于其上胚层紧邻前方的预期底板细胞不表达HNF-3β，这证明底板命运通常仅在这些细胞填充神经板中线并覆盖脊索之后才被确定。体内去除脊索会阻止底板发育，在此条件下，神经管腹侧中线的细胞不表达HNF-3β。脊索移植诱导异位底板发育和HNF-3β的异位神经表达。在体外，神经板外植体被脊索细胞以接触依赖但抗放线菌酮的方式诱导表达HNF-3β，这证明HNF-3β的表达是神经板细胞对脊索衍生诱导信号的直接反应。
