Chen Y Q, Sloan-Lancaster J, Berg D T, Richardson M A, Grinnell B, Tseng-Crank J
Department of Cardiovascular Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
Thromb Haemost. 2001 Dec;86(6):1563-72.
Plasminogen activator inhibitor-1 (PAI-1) is a serine protease inhibitor (SERPIN) specific for tissue-type and urokinase-like plasminogen activators. High plasma PAI-1 activity is a risk factor for thrombotic diseases. Due to the short half-life of PAI-1, regulation of PAI-1 gene expression and secretion of active PAI-1 into the blood stream is important for hemostatic balance. We have investigated transcriptional control of PAI-1 gene expression in bovine aortic endothelial cells (BAECs) and human cell lines using PAI-1 5' promoter-luciferase reporter assays. Contrary to the cytokine-induced up-regulation of PAI-1 mRNA and protein levels, we found that only transforming growth factor-beta (TGF-beta) was efficient in inducing PAI-1 promoter activation. Tissue necrosis factor-alpha (TNF-alpha) induced a small luciferase activity with the 2.5 kb PAI-1 promoter, but not with the PAI-800/4G/5G and p3TP-lux promoters. Next we investigated whether a lack of response to TNF-alpha was due to deficient signaling pathways. BAECs responded to TNF-alpha with robust NFkappaB promoter activation. TGF-beta activated the p38 MAP kinase, while TNF-alpha activated both the SAPK/JNK and p38 MAP kinases. The ERK1/2 MAP kinases were constitutively activated in BAECs. BAEC therefore responded to TNF-alpha stimulation with activation of the MAP kinases and the NFkappaB transcriptional factors. We further measured the messenger RNA stability under the influence by TGF-beta and TNF-alpha and found no difference. PAI-1 gene activation by TNF-alpha apparently is yet to be defined for the location of the response element and/or the signaling pathway, while TGF-beta is the most important cytokine for PAI-1 transcriptional activation through its 5' proximal promoter.
纤溶酶原激活物抑制剂-1（PAI-1）是一种特异性针对组织型和尿激酶型纤溶酶原激活物的丝氨酸蛋白酶抑制剂（SERPIN）。血浆PAI-1活性升高是血栓性疾病的一个危险因素。由于PAI-1半衰期较短，PAI-1基因表达的调控以及活性PAI-1分泌到血流中对于止血平衡很重要。我们使用PAI-1 5'启动子-荧光素酶报告基因分析，研究了牛主动脉内皮细胞（BAECs）和人细胞系中PAI-1基因表达的转录调控。与细胞因子诱导的PAI-1 mRNA和蛋白水平上调相反，我们发现只有转化生长因子-β（TGF-β）能有效诱导PAI-1启动子激活。肿瘤坏死因子-α（TNF-α）用2.5 kb的PAI-1启动子诱导出较小的荧光素酶活性，但用PAI-800/4G/5G和p3TP-lux启动子则不能。接下来我们研究了对TNF-α无反应是否是由于信号通路缺陷。BAECs对TNF-α有强烈的NFκB启动子激活反应。TGF-β激活p38丝裂原活化蛋白激酶（MAP激酶），而TNF-α激活SAPK/JNK和p38 MAP激酶。ERK1/2 MAP激酶在BAECs中组成性激活。因此，BAECs对TNF-α刺激有MAP激酶和NFκB转录因子的激活反应。我们进一步测量了在TGF-β和TNF-α影响下的信使RNA稳定性，未发现差异。TNF-α对PAI-1基因的激活显然尚未明确反应元件的位置和/或信号通路，而TGF-β是通过其5'近端启动子对PAI-1转录激活最重要的细胞因子。
