Prolonged hypoxia differentially regulates hypoxia-inducible factor (HIF)-1α and HIF-2α expression in lung epithelial cells -: Implication of natural antisense HIF-1α
Prolonged hypoxia differentially regulates hypoxia-inducible factor (HIF)-1α and HIF-2α expression in lung epithelial cells -: Implication of natural antisense HIF-1α
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DOI：
10.1074/jbc.m400461200
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发表时间：
2004-04-09
影响因子：
4.8
通讯作者：
Clerici, C
中科院分区：
文献类型：
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作者：
Uchida, T;Rossignol, F;Clerici, C
低氧诱导因子（HIF）-1是HIF-α和芳香烃受体核转运子亚基的异源二聚体，它介导了低氧的转录适应。HIF-1 α和HIF-2 α亚基都经历快速缺氧诱导的蛋白质稳定化，并结合相同的靶DNA序列。当在相似的细胞类型中共表达时，可能存在区别性的控制机制来调节它们，这解释了为什么HIF-1 α和HIF-2 α在胚胎发生过程中不被取代。我们报告，在人肺上皮细胞系（A549），HIF-1 α和HIF-2 α蛋白类似地诱导急性缺氧（4小时，0.5%O-2）在翻译或翻译后水平。然而，HIF-1 α和HIF-2 α的差异调节长时间缺氧（12小时，0.5%O-2），因为HIF-1 α蛋白的刺激消失，因为其mRNA的稳定性降低，而HIF-2 α蛋白的刺激保持高和稳定。长时间的缺氧也诱导了天然反义HIF-1 α（aHIF）数量的增加，其基因启动子包含几个推定的缺氧反应元件（正如我们在这里证实的）HIF-1 α或HIF-2 α蛋白可以结合。最后，用显性负性HIF-2 α瞬时转染A549细胞，同时也作为显性负性HIF-1 α，阻止了HIF-1 α蛋白的减少和aHIF转录的增加。总之，这些数据表明，在长期缺氧，HIF-α蛋白负调节HIF-1 α的表达，通过增加aHIF和HIF-1 α mRNA的不稳定。缺氧期间HIF-1 α和HIF-2 α之间的这种反式调节可能传递靶基因特异性。
Transcriptional adaptations to hypoxia are mediated by hypoxia-inducible factor (HIF)-1, a heterodimer of HIF-alpha and aryl hydrocarbon receptor nuclear translocator subunits. The HIF-1alpha and HIF-2alpha subunits both undergo rapid hypoxia-induced protein stabilization and bind identical target DNA sequences. When coexpressed in similar cell types, discriminating control mechanisms may exist for their regulation, explaining why HIF-1alpha and HIF-2alpha do not substitute during embryogenesis. We report that, in a human lung epithelial cell line (A549), HIF-1alpha and HIF-2alpha proteins were similarly induced by acute hypoxia (4 h, 0.5% O-2) at the translational or post-translational level. However, HIF-1alpha and HIF-2alpha were differentially regulated by prolonged hypoxia (12 h, 0.5% O-2) since HIF-1alpha protein stimulation disappeared because of a reduction in its mRNA stability, whereas HIF-2alpha protein stimulation remained high and stable. Prolonged hypoxia also induced an increase in the quantity of natural antisense HIF-1alpha(aHIF), whose gene promoter contains several putative hypoxia response elements to which (as we confirm here) the HIF-1alpha or HIF-2alpha protein can bind. Finally, transient transfection of A549 cells by dominant-negative HIF-2alpha, also acting as a dominant-negative for HIF-1alpha, prevented both the decrease in the HIF-1alpha protein and the increase in the aHIF transcript. Taken together, these data indicate that, during prolonged hypoxia, HIF-alpha proteins negatively regulate HIF-1alpha expression through an increase in aHIF and destabilization of HIF-1alpha mRNA. This transregulation between HIF-1alpha and HIF-2alpha during hypoxia likely conveys target gene specificity.