A circadian clock gene, PER2, activates HIF-1 as an effector molecule for recruitment of HIF-1α to promoter regions of its downstream genes
A circadian clock gene, PER2, activates HIF-1 as an effector molecule for recruitment of HIF-1α to promoter regions of its downstream genes
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DOI：
10.1111/febs.14280
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发表时间：
2017-11-01
期刊：
影响因子：
5.4
通讯作者：
Harada, Hiroshi
中科院分区：
文献类型：
--
作者：
Kobayashi, Minoru;Morinibu, Akiyo;Harada, Hiroshi
缺氧诱导因子1 （HIF-1）是一种参与细胞对缺氧适应性反应的转录因子。最近的研究表明，HIF-1的活性受到重要的生物钟基因之一，周期生物钟2 （PER2）的上调；然而，其潜在机制尚不清楚。在这里，我们发现PER2作为一种效应蛋白，将HIF-1募集到其同源增强子序列，即缺氧反应元件（HRE）。我们发现，PER2的强制表达增强了HIF-1的活性，而不影响HIF-1的调控亚基HIF-1在mRNA或蛋白质水平上的表达水平。一系列基于共免疫沉淀的实验表明，PER2与HIF-1相互作用，促进HIF-1募集到血管内皮生长因子（VEGF）启动子衍生的HRE。只有当缺氧刺激、引入N803A点突变或N803-双加氧酶抑制剂去铁胺保持HIF-1的803位天冬酰胺残基（HIF-1 N803）不被羟基化时，才能观察到per2介导的HIF-1活化。然而，无论N803羟基化状态如何，PER-2-HIF-1相互作用的程度是相同的。综上所述，这些结果表明，在N803羟基化状态的未知传感器分子的帮助下，PER2作为HIF-1募集到其下游基因启动子区域的效应分子。我们的研究结果揭示了HIF-1激活的一个新的调控步骤，可以针对HIF-1相关疾病（如癌症）制定治疗策略。
Hypoxia-inducible factor 1 (HIF-1) is a transcription factor functioning in cellular adaptive responses to hypoxia. Recent studies have suggested that HIF-1 activity is upregulated by one of the important circadian clock genes, period circadian clock 2 (PER2); however, its underlying mechanism remains unclear. Here, we show that PER2 functions as an effector protein for the recruitment of HIF-1 to its cognate enhancer sequence, the hypoxia-response element (HRE). We found that the forced expression of PER2 enhanced HIF-1 activity without influencing expression levels of the regulatory subunit of HIF-1, HIF-1, at either mRNA or protein levels. A series of coimmunoprecipitation-based experiments revealed that PER2 interacted with HIF-1 and facilitated the recruitment of HIF-1 to HRE derived from vascular endothelial growth factor (VEGF) promoter. The PER2-mediated activation of HIF-1 was observed only when the asparagine residue at position 803 of HIF-1 (HIF-1 N803) was kept unhydroxylated by hypoxic stimulation, by introducing an N803A point mutation, or by an inhibitor of N803-dioxygenase, deferoxamine. However, the extent of PER-2-HIF-1 interaction was equivalent regardless of the N803 hydroxylation status. Taken together, these results suggest that, with the help of an unknown sensor molecule for the N803 hydroxylation status, PER2 functions as an effector molecule for the recruitment of HIF-1 to promoter regions of its downstream genes. Our findings reveal a novel regulatory step in the activation of HIF-1, which can be targeted to develop therapeutic strategies against HIF-1-related diseases, such as cancers.