Differential roles of hypoxia-inducible factor 1alpha (HIF-1alpha) and HIF-2alpha in hypoxic gene regulation.
Differential roles of hypoxia-inducible factor 1alpha (HIF-1alpha) and HIF-2alpha in hypoxic gene regulation.
复制标题
DOI：
--
复制
发表时间：
2003
影响因子：
5.3
通讯作者：
Cheng-Jun Hu;Liyi Wang;L. Chodosh;B. Keith;M. Simon
中科院分区：
文献类型：
--
作者：
Cheng-Jun Hu;Liyi Wang;L. Chodosh;B. Keith;M. Simon
对缺氧的转录反应主要由缺氧诱导因子（HIF）介导，HIF是HIF α和芳烃受体核转运子亚基的异源二聚体。hif -1 α和hif -2 α亚基在DNA结合和二聚化结构域上结构相似，但在转激活结构域上不同，这意味着它们可能具有独特的靶基因。先前使用hif -1 α(-/-)胚胎干细胞和小鼠胚胎成纤维细胞的研究表明，hif -1 α的缺失消除了所有分析的氧调节转录反应，这表明hif -2 α在缺氧基因调控中是必不可少的。相比之下，HIF-2alpha在肺和其他组织的瞬时转染试验和胚胎发育过程中已被证明可以调节一些缺氧诱导基因。为了解决这一差异，并确定特定的HIF-2alpha靶基因，我们使用DNA微阵列分析来评估表达HIF-2alpha而不表达HIF-1alpha的细胞中的缺氧基因诱导。此外，我们设计了HEK293细胞，通过四环素调控的启动子表达稳定形式的HIF-1alpha或HIF-2alpha。在这项首次HIF-1alpha和HIF-2alpha靶基因的比较研究中，我们证明HIF-2alpha确实调节多种广泛表达的缺氧诱导基因，这表明其功能并不像最初认为的那样局限于内皮细胞特异性基因的表达。重要的是，HIF-1alpha（而不是HIF-2alpha）在两种类型的细胞中刺激糖酵解基因表达，首次清楚地表明HIF-1alpha和HIF-2alpha具有独特的靶点。
Transcriptional responses to hypoxia are primarily mediated by hypoxia-inducible factor (HIF), a heterodimer of HIF-alpha and the aryl hydrocarbon receptor nuclear translocator subunits. The HIF-1alpha and HIF-2alpha subunits are structurally similar in their DNA binding and dimerization domains but differ in their transactivation domains, implying they may have unique target genes. Previous studies using Hif-1alpha(-/-) embryonic stem and mouse embryonic fibroblast cells show that loss of HIF-1alpha eliminates all oxygen-regulated transcriptional responses analyzed, suggesting that HIF-2alpha is dispensable for hypoxic gene regulation. In contrast, HIF-2alpha has been shown to regulate some hypoxia-inducible genes in transient transfection assays and during embryonic development in the lung and other tissues. To address this discrepancy, and to identify specific HIF-2alpha target genes, we used DNA microarray analysis to evaluate hypoxic gene induction in cells expressing HIF-2alpha but not HIF-1alpha. In addition, we engineered HEK293 cells to express stabilized forms of HIF-1alpha or HIF-2alpha via a tetracycline-regulated promoter. In this first comparative study of HIF-1alpha and HIF-2alpha target genes, we demonstrate that HIF-2alpha does regulate a variety of broadly expressed hypoxia-inducible genes, suggesting that its function is not restricted, as initially thought, to endothelial cell-specific gene expression. Importantly, HIF-1alpha (and not HIF-2alpha) stimulates glycolytic gene expression in both types of cells, clearly showing for the first time that HIF-1alpha and HIF-2alpha have unique targets.