Lamb K A, Johnson L R, Rizzino A
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68198-6805, USA.
Mol Reprod Dev. 1997 Nov;48(3):301-9. doi: 10.1002/(SICI)1098-2795(199711)48:3<301::AID-MRD1>3.0.CO;2-V.
FGF-4 appears to be the first fibroblast growth factor (FGF) expressed during embryogenesis, and its expression is critical for early mammalian development. FGF-4 is expressed in the embryonic cell lines, F9, D3, and NT2/D1; but its expression in these cells is repressed upon differentiation. Transcription of the FGF-4 gene in embryonic cells is regulated by an enhancer in the third exon and by a positive regulatory region upstream of the transcription start site. A CCAAT box motif within the positive regulatory region has been shown to support FGF-4 expression, but the factor that binds to this site in vivo has not been identified. In this report, we demonstrate that the transcription factor complex NF-Y binds to the FGF-4 CCAAT box motif when nuclear extracts from each of the embryonic cell lines and their differentiated cells were examined by gel mobility shift analyses. Importantly, we demonstrate that expression of a dominant-negative NF-YA mutant protein reduces the expression of FGF-4 promoter/reporter gene constructs in F9 EC cells. Hence, we provide strong evidence that the transcription factor NF-Y is involved in the expression of the FGF-4 gene.
FGF-4似乎是胚胎发育过程中表达的首个成纤维细胞生长因子（FGF），其表达对早期哺乳动物发育至关重要。FGF-4在胚胎细胞系F9、D3和NT2/D1中表达；但其在这些细胞中的表达在分化时受到抑制。胚胎细胞中FGF-4基因的转录受第三外显子中的一个增强子以及转录起始位点上游的一个正调控区域调控。已表明正调控区域内的一个CCAAT框基序支持FGF-4表达，但尚未鉴定出在体内与该位点结合的因子。在本报告中，当通过凝胶迁移率变动分析检测每个胚胎细胞系及其分化细胞的核提取物时，我们证明转录因子复合物NF-Y与FGF-4 CCAAT框基序结合。重要的是，我们证明显性负性NF-YA突变蛋白的表达降低了F9胚胎癌细胞中FGF-4启动子/报告基因构建体的表达。因此，我们提供了有力证据表明转录因子NF-Y参与FGF-4基因的表达。
