Bian J, Sun Y
Department of Molecular Biology, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, Michigan 48105, USA.
Mol Cell Biol. 1997 Nov;17(11):6330-8. doi: 10.1128/MCB.17.11.6330.
p53, a tumor suppressor and a transcription factor, has been shown to transcriptionally activate the expression of a number of important genes involved in the regulation of cell growth, DNA damage, angiogenesis, and apoptosis. In a computer search for other potential p53 target genes, we identified a perfect p53 binding site in the promoter of the human type IV collagenase (also called 72-kDa gelatinase or matrix metalloproteinase 2 [MMP-2]) gene. This p53 binding site was found to specifically bind to p53 protein in a gel shift assay. Transcription assays with luciferase reporters driven by the promoter or enhancer of the type IV collagenase gene revealed that (i) activation of the promoter activity is p53 binding site dependent in p53-positive cells but not in p53-negative cells and (ii) wild-type p53, but not p53 mutants commonly found in human cancers, transactivates luciferase expression driven by the type IV collagenase promoter as well as by a p53 site-containing enhancer element in the promoter. Significantly, expression of the endogenous type IV collagenase is also under the control of p53. Treatment of U2-OS cells, a wild-type p53-containing osteogenic sarcoma line, with a common p53 inducer, etoposide, induced p53 DNA binding and transactivation activities in a time-dependent manner. Induction of type IV collagenase expression followed the p53 activation pattern. No induction of type IV collagenase expression can be detected under the same experimental conditions in p53-negative Saos-2 cells. All these in vitro and in vivo assays strongly suggest that the type IV collagenase gene is a p53 target gene and that its expression is subject to p53 regulation. Our finding links p53 to a member of the MMP genes, a family of genes implicated in trophoblast implantation, wound healing, angiogenesis, arthritis, and tumor cell invasion. p53 may regulate these processes by upregulating expression of type IV collagenase.
p53是一种肿瘤抑制因子和转录因子，已被证明可转录激活许多参与细胞生长、DNA损伤、血管生成和细胞凋亡调控的重要基因的表达。在通过计算机搜索其他潜在的p53靶基因时，我们在人IV型胶原酶（也称为72 kDa明胶酶或基质金属蛋白酶2 [MMP-2]）基因的启动子中鉴定出一个完美的p53结合位点。在凝胶迁移实验中发现该p53结合位点能特异性结合p53蛋白。用IV型胶原酶基因的启动子或增强子驱动的荧光素酶报告基因进行转录分析表明：（i）在p53阳性细胞中，启动子活性的激活依赖于p53结合位点，而在p53阴性细胞中则不然；（ii）野生型p53可激活由IV型胶原酶启动子以及启动子中含p53位点的增强子元件驱动的荧光素酶表达，而人类癌症中常见的p53突变体则不能。值得注意的是，内源性IV型胶原酶的表达也受p53的调控。用常见的p53诱导剂依托泊苷处理U2-OS细胞（一种含野生型p53的骨肉瘤细胞系），可随时间依赖性诱导p53的DNA结合和反式激活活性。IV型胶原酶表达的诱导遵循p53激活模式。在相同实验条件下，在p53阴性的Saos-2细胞中未检测到IV型胶原酶表达的诱导。所有这些体外和体内实验都强烈表明IV型胶原酶基因是一个p53靶基因，其表达受p53调控。我们的发现将p53与MMP基因家族的一个成员联系起来，该基因家族与滋养层植入、伤口愈合、血管生成、关节炎和肿瘤细胞侵袭有关。p53可能通过上调IV型胶原酶的表达来调节这些过程。
