Jaakkola P, Vihinen T, Jalkanen M
Turku Centre for Biotechnology, University of Turku and Abo Akademi University, Tykistökatu 6B, BioCity, Turku, FIN-20520, Finland.
Biochem Biophys Res Commun. 2000 Nov 19;278(2):432-9. doi: 10.1006/bbrc.2000.3812.
Far upstream enhancers are predicted to act by looping and activating general transcription factors on core promoters and to require proximal promoter sequences for appropriate gene activation in time and space. We have previously described an FGF-inducible response element (FiRE) located far upstream on the syndecan-1 gene. The FiRE is activated specifically by members of the fibroblast growth factor (FGF) family in NIH3T3 cells. Here we describe the requirements of syndecan-1 proximal promoter for the activation of FiRE by FGF-2. Transient and stable transfections revealed that neither proximal promoter SP1 sites nor TATA-box are required for the FGF-2 induced activation of FiRE. Notably, the enhancer is activated in both orientations by FGF-2 even in the absence of proximal promoter. Importantly, removal of the promoter did not affect the growth factor specificity of FiRE. Proximal promoter independent activation of syndecan-1 gene by FGF-2 might be required during development when syndecan-1 proximal promoter needs to be largely attenuated but simultaneous transient and rapid FGF-2 induced transcription is required.
远上游增强子据预测是通过环化作用并激活核心启动子上的通用转录因子来发挥作用的，并且在时间和空间上进行适当的基因激活需要近端启动子序列。我们之前描述过一个位于syndecan-1基因远上游的FGF诱导反应元件（FiRE）。该FiRE在NIH3T3细胞中被成纤维细胞生长因子（FGF）家族成员特异性激活。在此我们描述了syndecan-1近端启动子对于FGF-2激活FiRE的要求。瞬时转染和稳定转染表明，FGF-2诱导的FiRE激活既不需要近端启动子的SP1位点，也不需要TATA框。值得注意的是，即使在没有近端启动子的情况下，增强子也能被FGF-2以两种方向激活。重要的是，去除启动子并不影响FiRE的生长因子特异性。在发育过程中，当syndecan-1近端启动子需要大幅减弱但同时又需要FGF-2诱导的瞬时快速转录时，可能需要FGF-2对syndecan-1基因进行近端启动子非依赖性激活。
