Chavrier P, Vesque C, Galliot B, Vigneron M, Dollé P, Duboule D, Charnay P
European Molecular Biology Laboratory, Heidelberg, FRG.
EMBO J. 1990 Apr;9(4):1209-18. doi: 10.1002/j.1460-2075.1990.tb08228.x.
Krox-20 is a mouse zinc finger gene expressed in a segment-specific manner in the early central nervous system, which makes it a potential developmental control gene. In this report, we show that the Krox-20 protein binds in vitro to two specific DNA sites located upstream from the homeobox containing gene Hox-1.4. The nucleotide sequence recognized by Krox-20 is closely related to the Sp1 target sequence, which is consistent with the similarity existing between the zinc fingers of the two proteins. In co-transfection experiments in cultured cells, Krox-20 dramatically activates transcription from the herpes simplex virus thymidine kinase promoter when an oligomer of its binding site is present in cis close to the promoter. Analysis of mutated binding sites demonstrates that the level of activation by Krox-20 correlates with the affinity of the protein for the mutant sequence. These data indicate that Krox-20 constitutes a sequence-specific DNA-binding transcription factor. Parallel analysis of the expression of Krox-20 and Hox-1.4 in the neural tube by in situ hybridization revealed no overlap, arguing against direct interactions between these two genes. The possible involvement of Krox-20 in the regulation of the transcription of other homeobox genes is discussed in view of their respective patterns of expression.
Krox-20是一种小鼠锌指基因，在早期中枢神经系统中以片段特异性方式表达，这使其成为一种潜在的发育控制基因。在本报告中，我们表明Krox-20蛋白在体外与位于含同源盒基因Hox-1.4上游的两个特定DNA位点结合。Krox-20识别的核苷酸序列与Sp1靶序列密切相关，这与两种蛋白质的锌指之间存在的相似性一致。在培养细胞的共转染实验中，当Krox-20结合位点的寡聚体顺式存在于启动子附近时，它会显著激活单纯疱疹病毒胸苷激酶启动子的转录。对突变结合位点的分析表明，Krox-20的激活水平与蛋白质对突变序列的亲和力相关。这些数据表明Krox-20构成一种序列特异性DNA结合转录因子。通过原位杂交对神经管中Krox-20和Hox-1.4的表达进行的平行分析显示没有重叠，这表明这两个基因之间不存在直接相互作用。鉴于它们各自的表达模式，讨论了Krox-20可能参与其他同源盒基因转录调控的情况。
