Placenta growth factor gene expression is induced by hypoxia in fibroblasts: a central role for metal transcription factor-1.
Placenta growth factor gene expression is induced by hypoxia in fibroblasts: a central role for metal transcription factor-1.
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发表时间：
2001-03
期刊：
影响因子：
11.2
通讯作者：
Christopher J. Green;P. Lichtlen;Nhung T. Huynh;M. Yanovsky;K. Laderoute;W. Schaffner;Brian J. Murphy
中科院分区：
文献类型：
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作者：
Christopher J. Green;P. Lichtlen;Nhung T. Huynh;M. Yanovsky;K. Laderoute;W. Schaffner;Brian J. Murphy
胎盘生长因子（PlGF）是一种内皮细胞有丝分裂原，可增强血管内皮生长因子的生长和透化作用。在这里，我们报告，缺氧诱导表达的PlGF mRNA和蛋白质在永生化/转化的小鼠胚胎成纤维细胞（mEFs）和NIH 3 T3细胞。重要的是，致癌Ras的存在增强了缺氧诱导PlGF表达的幅度。为了研究低氧诱导PlGF表达的转录成分，我们克隆并测序了小鼠基因5 '侧翼区的1350 bp片段。启动子区的分析表明，存在公认的共识序列已知的缺氧反应的调控位点，包括金属反应元件和Sp1样网站。在本研究中，我们表明，诱导PlGF表达缺氧是依赖于金属反应元件结合转录因子1（MTF-1）的存在。因此，与野生型mEFs相比，在靶向缺失两个MTF-1等位基因的mEFs中，缺氧诱导的PIGF mRNA和蛋白水平的增加大大减弱。此外，瞬时转染的PlGF启动子报告基因到NIH 3 T3细胞导致缺氧反应的转录激活的报告。最后，MTF-1的异位表达导致PlGF启动子报告基因的基础转录活性增加。总之，这些发现表明PlGF基因对缺氧有反应，并且这种反应由MTF-1介导。它仍然有待确定是否这种激活是直接和/或间接转录激活MTF-1的结果。致癌Ras对低氧细胞中PlGF表达诱导的刺激作用表明，PlGF可能是肿瘤微环境中重要的促血管生成因子。
Placenta growth factor (PlGF) is a mitogen for endothelial cells that can potentiate the growth and permeabilizing effects on endothelium of vascular endothelial growth factor. Here we report that hypoxia induces the expression of both PlGF mRNA and protein in immortalized/transformed mouse embryonic fibroblasts (mEFs) and in NIH 3T3 cells. Importantly, the magnitude of the induction of PlGF expression by hypoxia is enhanced by the presence of oncogenic Ras. To investigate the transcriptional component of hypoxia-inducible PlGF expression, we cloned and sequenced a 1350-bp fragment of the 5'-flanking region of the mouse gene. Analysis of the promoter region indicated the presence of putative consensus sequences for known hypoxia-responsive regulatory sites, including metal response elements and Sp1-like sites. In the present study, we show that the induction of PlGF expression by hypoxia is dependent on the presence of the metal response element-binding transcription factor 1 (MTF-1). Thus, in mEFs with targeted deletions of both MTF-1 alleles, hypoxia-induced increases of PIGF mRNA and protein levels were greatly attenuated compared with those in wild-type mEFs. Moreover, transient transfection of a PlGF promoter reporter gene into NIH 3T3 cells resulted in hypoxia-responsive transcriptional activation of the reporter. Finally, ectopic expression of MTF-1 resulted in increased basal transcriptional activity of a PlGF promoter reporter. Together, these findings demonstrate that the PlGF gene is responsive to hypoxia and that this response is mediated by MTF-1. It remains to be determined whether this activation is the result of direct and/or indirect transcriptional activation by MTF-1. The stimulatory effect of oncogenic Ras on the induction of PlGF expression in hypoxic cells suggests that PlGF could be an important proangiogenic factor in the tumor microenvironment.