Hypoxia-inducible mammalian gene expression analyzed in vivo at a TATA-driven promoter and at an initiator-driven promoter
Hypoxia-inducible mammalian gene expression analyzed in vivo at a TATA-driven promoter and at an initiator-driven promoter
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DOI：
10.1074/jbc.273.37.23837
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发表时间：
1998-09-11
影响因子：
4.8
通讯作者：
Whitlock, JP
中科院分区：
文献类型：
--
作者：
Okino, ST;Chichester, CH;Whitlock, JP
我们已经分析了蛋白质-DNA相互作用在体内的转录控制元件的两个缺氧诱导基因在小鼠肝癌细胞。磷酸甘油酸激酶1（PGK 1）基因的启动子含有起始元件，但不含TATA序列，而葡萄糖转运蛋白1（Glut 1）基因的启动子含有TATA元件，但不含起始序列。我们的研究结果揭示了缺氧诱导，Arnt依赖的DNA识别位点的缺氧诱导因子1（HIF-1）上游的两个靶基因的占用。5个识别位点中保守的识别基序为5 '-CGTG-3'。PGK 1启动子表现出一个未知蛋白质的结合位点的组成型占用;然而，我们在未诱导或诱导的细胞中均未检测到起始元件处的蛋白质-DNA相互作用。Glut 1启动子也表现出组成性蛋白结合;此外，TATA元件在未诱导的细胞中表现出部分占用，并在缺氧条件下增加占用。我们没有发现缺氧诱导的染色质结构的变化，无论是基因的证据。Glut 1基因的时程分析揭示了HIF-1位点和TATA元件占用率之间的时间关系。我们的研究结果表明，这两个缺氧反应基因的启动子组成性地保持一个可访问的染色质构型，HIF-1通过在两个启动子处招募和/或稳定转录因子（如TFIID）来促进转录。
We have analyzed protein-DNA interactions in vivo at transcriptional control elements for two hypoxia-inducible genes in mouse hepatoma cells. The promoter for the phosphoglycerate kinase 1 (PGK1) gene contains an initiator element, but no TATA sequence, whereas the promoter for the glucose transporter 1 (Glut1) gene contains a TATA element but no initiator sequence. Our findings reveal hypoxia-inducible, Arnt-dependent occupancy of DNA recognition sites for hypoxia-inducible factor 1 (HIF-1) upstream of both target genes. The conserved recognition motif among the five recognition sites is 5'-CGTG-3'. The PGK1 promoter exhibits constitutive occupancy of a binding site for an unknown protein(s); however, we detect no protein-DNA interaction at the initiator element, in either uninduced or induced cells. The Glut1 promoter also exhibits constitutive protein binding; in addition, the TATA element exhibits partial occupancy in uninduced cells and increased occupancy under hypoxic conditions. We find no evidence for hypoxia-induced changes in chromatin structure of either gene. Time-course analyses of the Glut1 gene reveal a temporal relationship between occupancy of HIF-1 sites and TATA element occupancy. Our findings suggest that the promoters for both hypoxia-responsive genes constitutively maintain an accessible chromatin configuration and that HIF-1 facilitates transcription by recruiting and/or stabilizing a transcription factor(s), such as TFIID, at both promoters.