Role of ETS transcription factors in the hypoxia-inducible factor-2 target gene selection
Role of ETS transcription factors in the hypoxia-inducible factor-2 target gene selection
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DOI：
10.1158/0008-5472.can-05-3345
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发表时间：
2006-06-01
期刊：
影响因子：
11.2
通讯作者：
Barrett, J. Carl
中科院分区：
文献类型：
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作者：
Aprelikova, Olga;Wood, Matthew;Barrett, J. Carl
肿瘤缺氧通常与侵袭性表型、转移进展和化疗耐药性直接相关。两种转录因子[缺氧诱导因子-1 α（HIF-1 α）和HIF-2 α]在缺氧区域被显著诱导，并调节肿瘤适应低氧条件所必需的基因的表达;然而，这些因子的相对贡献是有争议的。我们使用RNA干扰介导的HIF-1 α或HIF-2 α的失活，然后通过微阵列分析来鉴定在缺氧中由HIF-1或HIF-2特异性调控的基因。我们发现，在MCF 7细胞系中，绝大多数缺氧反应基因（> 80%）依赖于HIF-1 α的存在。然而，一小群基因优先受HIF-2 α调控。对这组基因的启动子分析显示，它们都具有ETS家族转录因子的假定结合位点，并且11个HIF-2 α依赖性基因中的10个在ETS转录因子结合位点附近具有至少一个潜在的低氧应答元件（HRE）。ELK-1是ETS家族中最常见的成员，敲低ELK-1可显著降低HIF-2 α依赖性基因的缺氧诱导。ELK-1和HIF-2 α之间的物理和功能相互作用通过这两种蛋白质的共免疫沉淀、使用CITED 2启动子的荧光素酶报告基因测定以及ELK-1蛋白与HRE附近的CITED 2和WISP 2基因的启动子的结合来支持。这些数据表明，HIF-1或HIF-2对靶基因的选择取决于HIF的可用性以及与识别其启动子中同源元件的其他因子的合作。
Tumor hypoxia often directly correlates with aggressive phenotype, metastasis progression, and resistance to chemotherapy. Two transcription factors [hypoxia-inducible factor-1 alpha (HIF-1 alpha) and HIF-2 alpha] are dramatically induced in hypoxic areas and regulate the expression of genes necessary for tumor adaptation to the conditions of low oxygen; however, the relative contribution of these factors is controversial. We used RNA interference-mediated inactivation of HIF-1 alpha or HIF-2 alpha followed by microarray analysis to identify genes specifically regulated by either HIF-1 or HIF-2 in hypoxia. We found that, in the MCF7 cell line, the vast majority of hypoxia-responsive genes (> 80%) were dependent on the presence of HIF-1 alpha. However, a small group of genes were preferentially regulated by HIF-2 alpha. Promoter analysis for this group of genes revealed that all of them have putative binding sites for ETS family transcription factors, and 10 of 11 HIF-2 alpha-dependent genes had at least one potential hypoxia-responsive element (HRE) in proximity to an ETS transcription factor binding site. Knockdown of ELK-1, the most often represented member of ETS family, significantly reduced hypoxic induction of the HIF-2 alpha-dependent genes. Physical and functional interaction between ELK-1 and HIF-2 alpha were supported by coimmunoprecipitation of these two proteins, luciferase reporter assay using CITED2 promoter, and binding of ELK-1 protein to the promoters of CITED2 and WISP2 genes in proximity to a HRE. These data suggest that the choice of the target genes by HIF-1 or HIF-2 depends on availability and cooperation of HIFs with other factors recognizing their cognate elements in the promoters.