Wang Heng, Hicks John, Khanbolooki Parham, Kim Sun-Jin, Yan Chunhong, Wang Yao, Boyd Douglas
Department of Cancer Biology, MD Anderson Cancer Center, Houston, Texas 77030, USA.
Am J Pathol. 2003 Aug;163(2):453-64. doi: 10.1016/S0002-9440(10)63675-9.
The urokinase-type plasminogen activator receptor (u-PAR) contributes to cell migration and proteolysis in normal and cancerous tissues. Currently, there are no reports on the regulatory regions directing tissue-specific expression. Consequently, we undertook a study to identify novel promoter regions required for expression of this gene in transgenic mice bearing a LacZ reporter regulated by varying amounts (0.4, 1.5, and 8.5 kb) of upstream sequence. The 0.4-kb u-PAR upstream sequence directed weak and strong LacZ expression in the placenta and epididymis, respectively, both of which are tissues that express endogenous u-PAR. Conversely, transgene expression in the apical cells of the colon positive for endogenous u-PAR protein required 1.5 kb of upstream sequence for optimal expression. Furthermore, chromatin accessibility assays coupled with real-time polymerase chain reaction suggested a putative regulatory region spanning -1295/-1192 driving u-PAR expression in colonic cells. Interestingly, placental transgene expression was augmented with the 8.5-kb upstream fragment compared with the shorter 1.5-kb fragment indicating contributing element(s) between -1.5 and -8.5 kb. Thus, while 0.4 kb of upstream sequence directs u-PAR expression in the epididymis, sequences located between -0.4 and -1.5 kb and between -1.5 and -8.5 kb are required for optimal tissue-specific expression in the colon and the placenta, respectively.
尿激酶型纤溶酶原激活物受体（u-PAR）在正常组织和癌组织中有助于细胞迁移和蛋白水解。目前，尚无关于指导组织特异性表达的调控区域的报道。因此，我们进行了一项研究，以确定在携带由不同长度（0.4、1.5和8.5 kb）上游序列调控的LacZ报告基因的转基因小鼠中，该基因表达所需的新启动子区域。0.4 kb的u-PAR上游序列分别在胎盘和附睾中指导LacZ的弱表达和强表达，这两个组织均表达内源性u-PAR。相反，在内源性u-PAR蛋白呈阳性的结肠顶端细胞中，转基因表达需要1.5 kb的上游序列才能实现最佳表达。此外，染色质可及性分析与实时聚合酶链反应表明，存在一个推定的调控区域，跨度为-1295/-1192，驱动结肠细胞中u-PAR的表达。有趣的是，与较短的1.5 kb片段相比，8.5 kb的上游片段增强了胎盘转基因的表达，表明在-1.5至-8.5 kb之间存在起作用的元件。因此，虽然0.4 kb的上游序列指导附睾中u-PAR的表达，但分别需要-0.4至-1.5 kb之间以及-1.5至-8.5 kb之间的序列才能在结肠和胎盘中实现最佳的组织特异性表达。
