Murakami A, Thurlow J, Dickson C
Department of Viral Oncology, Institute for Virus Research, Kyoto University, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
J Biol Chem. 1999 Jun 11;274(24):17242-8. doi: 10.1074/jbc.274.24.17242.
fgf-3 shows a complex spatial-temporal pattern of transcription during mouse development, and the gene product appears to be an important intercellular signaling molecule. Here we show that the major enhancer, which is obligatory for transcription, is composed of three elements with different properties. Both functional analyses in undifferentiated and differentiated F9 cells and characterization of DNA-protein complexes in vitro have identified the sequence motifs GTGACT(C), ATTGT, and GATA as the key transcription factor binding sites. The GTGACT(C) motif, while not essential, is required for full enhancer activity. However, binding at ATTGT is crucial for transcriptional activity and is required for cooperative binding at the proximal GATA site. The GATA binding site mediates the retinoic acid/dibutyryl cyclic AMP stimulation of transcription and correlates with the binding of Gata-4 which is induced by retinoic acid in differentiating F9 cells. The ATTGT and GATA motifs are inactive when placed separately on a minimal thymidine kinase (TK) promoter, but together they act as a strong retinoic acid-regulated enhancer. In undifferentiated F9 cells, gata-4 expression stimulates the fgf-3 promoter, whereas in differentiated F9 cells already expressing gata-4, no further increase in promoter activity was observed.
Fgf-3在小鼠发育过程中呈现出复杂的时空转录模式，其基因产物似乎是一种重要的细胞间信号分子。在此我们表明，转录所必需的主要增强子由三个具有不同特性的元件组成。对未分化和分化的F9细胞进行的功能分析以及体外DNA-蛋白质复合物的表征均已确定序列基序GTGACT(C)、ATTGT和GATA为关键转录因子结合位点。GTGACT(C)基序虽非必需，但对增强子的完全活性是必需的。然而，在ATTGT处的结合对转录活性至关重要，并且是在近端GATA位点协同结合所必需的。GATA结合位点介导视黄酸/二丁酰环磷酸腺苷对转录的刺激，并与分化的F9细胞中由视黄酸诱导的Gata-4的结合相关。当ATTGT和GATA基序分别置于最小胸苷激酶（TK）启动子上时无活性，但它们一起可作为一个强大的视黄酸调节增强子。在未分化的F9细胞中，gata-4的表达刺激fgf-3启动子，而在已表达gata-4的分化F9细胞中，未观察到启动子活性的进一步增加。
