Bastian H, Gruss P
Department of Molecular Cell Biology, Max-Planck Institute of Biophysical Chemistry, Göttingen, FRG.
EMBO J. 1990 Jun;9(6):1839-52. doi: 10.1002/j.1460-2075.1990.tb08309.x.
Using the Drosophila even-skipped (eve) homeobox as a probe, we have isolated two murine genes, Evx 1 and Evx 2, from a genomic library. Evx 1, Evx 2, eve and the Xenopus Xhox-3 constitute a family of related genes based on similar homeodomain sequences. In addition, Evx 1 and Evx 2 share extended amino acid conservation outside of the homeobox. The Evx 1 protein consists of 416 amino acids as deduced from the longest open reading frame of Evx 1 cDNAs. Evx 1 is located 3.7 cM from the Hox 5 locus on mouse chromosome 2. It is expressed in undifferentiated F9 stem cells but not in cells differentiated with retinoic acid and cAMP. During embryogenesis, Evx 1 shows a biphasic expression pattern. From days 7 to 9 p.c. Evx 1 expression emerges at the posterior end of the embryo within the primitive ectoderm, and later in the mesoderm and neuroectoderm. From days 10 to 12.5 p.c. Evx 1 transcripts are restricted to specific cells within the neural tube and hindbrain along their entire lengths and coincides temporally, as well as spatially, with maturation of early forming interneurons, possibly commissural interneurons. The early and late transcription pattern is compatible with a role of Evx 1 in specifying posterior positional information along the embryonic axis similar to the Xenopus Xhox-3 and in specifying neuronal cell fates within the differentiating neural tube in analogy to eve in the embryonic central nervous system of Drosophila, respectively.
我们以果蝇的偶数缺口（eve）同源异型框为探针，从基因组文库中分离出了两个小鼠基因，即Evx 1和Evx 2。基于相似的同源结构域序列，Evx 1、Evx 2、eve和非洲爪蟾的Xhox-3构成了一个相关基因家族。此外，Evx 1和Evx 2在同源异型框之外还具有广泛的氨基酸保守性。根据Evx 1 cDNA最长的开放阅读框推测，Evx 1蛋白由416个氨基酸组成。Evx 1位于小鼠2号染色体上距Hox 5位点3.7 cM处。它在未分化的F9干细胞中表达，但在经视黄酸和cAMP分化的细胞中不表达。在胚胎发育过程中，Evx 1呈现双相表达模式。在胚胎发育第7至9天，Evx 1表达出现在胚胎后端的原始外胚层内，随后出现在中胚层和神经外胚层。在胚胎发育第10至12.5天，Evx 1转录本局限于神经管和后脑内的特定细胞全长范围内，并且在时间和空间上与早期形成的中间神经元（可能是连合中间神经元）的成熟过程相吻合。早期和晚期的转录模式分别与Evx 1在沿胚胎轴确定后部位置信息方面的作用（类似于非洲爪蟾的Xhox-3）以及在分化的神经管内确定神经元细胞命运方面的作用（类似于果蝇胚胎中枢神经系统中的eve）相一致。
