Cooperative interaction of hypoxia-inducible factor-2α (HIF-2α) and Ets-1 in the transcriptional activation of vascular endothelial growth factor receptor-2 (Flk-1)
Cooperative interaction of hypoxia-inducible factor-2α (HIF-2α) and Ets-1 in the transcriptional activation of vascular endothelial growth factor receptor-2 (Flk-1)
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DOI：
10.1074/jbc.m211298200
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发表时间：
2003-02-28
影响因子：
4.8
通讯作者：
Flamme, I
中科院分区：
文献类型：
--
作者：
Elvert, G;Kappel, A;Flamme, I
Ets家族成员与多种其他转录因子之间的相互作用在发育和分化过程中发挥着重要作用，例如，在造血系统中。在这里，我们发现内皮碱性螺旋-环-螺旋PAS结构域转录因子缺氧诱导因子2α（HIF-2α）（但不是其近亲HIF-1α）与Ets-1合作激活血管内皮生长因子受体2（VEGF-2）基因（Flk-1）的转录。受体酪氨酸激酶Flk-1对于血管生成是不可或缺的，其表达在发育过程中受到密切调节。与 HIF-2α 在体内控制 Flk-1 表达的假设一致，我们在此表明 HIF-2α 和 Flk-1 在出生后小鼠脑毛细血管中共同调节。在 Flk-1 启动子内鉴定出串联 HIF-2α/Ets 结合位点，该位点充当强增强子元件。根据对转基因小鼠胚胎的分析，这些基序对于内皮细胞特异性报告基因表达至关重要。当与异源启动子融合时，单个 HIF-2α/Ets 元件赋予 HIF-2α 和 Ets-1 强烈的协同诱导作用，并且在内皮细胞中最活跃。 HIF-2α 与 Ets-1 的物理相互作用已被证明并分别定位于 HIF-2α 羧基末端和 Ets-1 的自抑制外显子 VII 结构域。分别删除 HIF-2α 的 DNA 结合域和羧基末端反式激活结构域，产生了显性失活突变体，该突变体抑制了野生型蛋白的反式激活，并且无法与 Ets-1 协同作用。这些结果表明，HIF-2α 和内皮 Ets 因子之间的相互作用是内皮细胞中 Flk-1 完全转录激活所必需的，因此可能代表未来操纵血管生成的目标。
Interactions between Ets family members and a variety of other transcription factors serve important functions during development and differentiation processes, e.g. in the hematopoietic system. Here we show that the endothelial basic helix-loop-helix PAS domain transcription factor, hypoxia-inducible factor-2alpha (HIF-2alpha) (but not its close relative HIF-1alpha), cooperates with Ets-1 in activating transcription of the vascular endothelial growth factor receptor-2 (VEGF-2) gene (Flk-1). The receptor tyrosine kinase Flk-1 is indispensable for angiogenesis, and its expression is closely regulated during development. Consistent with the hypothesis that HIF-2alpha controls the expression of Flk-1 in vivo, we show here that HIF-2alpha and Flk-1 are co-regulated in postnatal mouse brain capillaries. A tandem HIF-2alpha/Ets binding site was identified within the Flk-1 promoter that acted as a strong enhancer element. Based on the analysis of transgenic mouse embryos, these motifs are essential for endothelial cell-specific reporter gene expression. A single HIF-2alpha/Ets element conferred strong cooperative induction by HIF-2alpha and Ets-1 when fused to a heterologous promoter and was most active in endothelial cells. The physical interaction of HIF-2alpha with Ets-1 was demonstrated and localized to the HIF-2alpha carboxyl terminus and the autoinhibitory exon VII domain of Ets-1, respectively. The deletion of the DNA binding and carboxyl-terminal transactivation domains of HIF-2alpha, respectively, created dominant negative mutants that suppressed transactivation by the wild type protein and failed to synergize with Ets-1. These results suggest that the interaction between HIF-2alpha and endothelial Ets factors is required for the full transcriptional activation of Flk-1 in endothelial cells and may therefore represent a future target for the manipulation of angiogenesis.