Bulens F, Ibañez-Tallon I, Van Acker P, De Vriese A, Nelles L, Belayew A, Collen D
Center for Molecular and Vascular Biology, University of Leuven, Belgium.
J Biol Chem. 1995 Mar 31;270(13):7167-75. doi: 10.1074/jbc.270.13.7167.
All-trans-retinoic acid (RA) and retinoids induce synthesis of tissue-type plasminogen activator (t-PA) in endothelial and neuroblastoma cells in vitro and in rats in vivo. In HT1080 fibrosarcoma cells, induction of t-PA-related antigen secretion and t-PA mRNA steady state levels by RA were found to depend on de novo protein and mRNA synthesis. Fragments derived from the 5'-flanking region of the t-PA gene (+197 to -9578 base pairs (bp)) were linked to the chloramphenicol acetyltransferase gene. Transfection studies demonstrated that the region spanning bp -7145 to -9578 mediated induction by RA. A functional retinoic acid response element (RARE), consisting of a direct repeat of the GGGTCA motif spaced by 5 nucleotides (t-PA/DR5), was localized at -7.3 kilobases. The t-PA/DR5 element interacted with the heterodimer composed of retinoic acid receptor alpha and retinoid X receptor alpha in vitro, whereas its mutation abolished induction by RA in transient expression. In human EA.hy926 hybrid endothelial and in SK-N-SH neuroblastoma cells, the activity of t-PA/DR5 was found to be independent of the intervening sequence (-632 to -7144 bp) and of its distance from the transcription initiation site. Staurosporine, an inhibitor of protein kinase activity, inhibited induction by RA, suggesting that it required protein phosphorylation.
全反式维甲酸（RA）和类视黄醇在体外培养的内皮细胞和成神经细胞瘤细胞以及体内的大鼠中均可诱导组织型纤溶酶原激活物（t-PA）的合成。在HT1080纤维肉瘤细胞中，发现RA诱导t-PA相关抗原分泌和t-PA mRNA稳态水平依赖于从头合成蛋白质和mRNA。将源自t-PA基因5'侧翼区（+197至-9578碱基对（bp））的片段与氯霉素乙酰转移酶基因相连。转染研究表明，跨越bp -7145至-9578的区域介导了RA的诱导作用。一个功能性视黄酸反应元件（RARE），由间隔5个核苷酸的GGGTCA基序直接重复组成（t-PA/DR5），定位于-7.3千碱基处。t-PA/DR5元件在体外与由视黄酸受体α和类视黄醇X受体α组成的异二聚体相互作用，而其突变则消除了瞬时表达中RA的诱导作用。在人EA.hy926杂交内皮细胞和SK-N-SH成神经细胞瘤细胞中，发现t-PA/DR5的活性与中间序列（-632至-7144 bp）及其与转录起始位点的距离无关。蛋白激酶活性抑制剂星形孢菌素抑制了RA的诱导作用，表明其诱导作用需要蛋白质磷酸化。
