RNA-Binding proteins HuR and PTB promote the translation of hypoxia-inducible factor 1α
RNA-Binding proteins HuR and PTB promote the translation of hypoxia-inducible factor 1α
复制标题
DOI：
10.1128/mcb.00973-07
复制
发表时间：
2008-01-01
影响因子：
5.3
通讯作者：
Gorospe, Myriam
中科院分区：
文献类型：
--
作者：
Galban, Stefanie;Kuwano, Yuki;Gorospe, Myriam
缺氧诱导因子1α（HIF-1α）的水平受到严格控制。在这里，我们研究了人宫颈癌HELA细胞中HIF-1α表达的转录后调节，对缺氧模仿COCL2反应。 HIF-1α水平在未经处理的细胞中无法检测到，在COCL2处理的细胞中，HIF-1α水平急剧增加，而HIF-1 Alpha mRNA水平没有变化。通过从头翻译分析确定并通过监测HIF-1 Alpha mRNA的多个多体膜相关性，通过COCL进行了HIF-1 Alpha翻译，可将HIF-1 Alpha翻译有效地升高。发现HIF-1 Alpha 5'未翻译区域（UTR）中的内部核糖体入口位点可以组成构成增强翻译，但并未进一步诱导转化，以响应COCL，治疗。取而代之的是，我们假设RNA结合蛋白HUR和PTB先前显示结合HIF-1αmRNA，在COCL2处理后参加了其翻译上调。实际上，发现两种RNA结合蛋白都以COCL2诱导方式结合HIF-1αmRNA，通过免疫沉淀内源性核糖核蛋白复合物评估。使用嵌合记者，发现息肉酰胺 - 结合蛋白（PTB）结合了HIF-1 Alpha 3'utr，而HUR主要与5'UTR相关。使用RNA干扰降低PTB表达或HUR表达可降低HIF-1α翻译和表达水平，而不是HIF-1αmRNA丰度。相反，HUR过表达后，HIF-1α的表达和对COCL2的翻译显着升高。我们建议HUR和PTB响应COCL2，共同上调HIF-1 Alpha翻译。
The levels of hypoxia-inducible factor 1 alpha (HIF-1 alpha) are tightly controlled. Here, we investigated the post-transcriptional regulation of HIF-1 alpha expression in human cervical carcinoma HeLa cells responding to the hypoxia mimetic CoCl2. Undetectable in untreated cells, HIF-1 alpha levels increased dramatically in CoCl2-treated cells, while HIF-1 alpha mRNA levels were unchanged. HIF-1 alpha translation was potently elevated by CoCl, treatment, as determined by de novo translation analysis and by monitoring the polysomal association of HIF-1 alpha mRNA. An internal ribosome entry site in the HIF-1 alpha 5' untranslated region (UTR) was found to enhance translation constitutively, but it did not further induce translation in response to CoCl, treatment. Instead, we postulated that RNA-binding proteins HuR and PTB, previously shown to bind HIF-1 alpha mRNA, participated in its translational upregulation after CoCl2 treatment. Indeed, both RNA-binding proteins were found to bind HIF-1 alpha mRNA in a CoCl2-inducible manner as assessed by immunoprecipitation of endogenous ribonucleoprotein complexes. Using a chimeric reporter, polypyrimidine tract-binding protein (PTB) was found to bind the HIF-1 alpha 3'UTR, while HuR associated principally with the 5'UTR. Lowering PTB expression or HuR expression using RNA interference reduced HIF-1 alpha translation and expression levels but not HIF-1 alpha mRNA abundance. Conversely, HIF-1 alpha expression and translation in response to CoCl2 were markedly elevated after HuR overexpression. We propose that HuR and PTB jointly upregulate HIF-1 alpha translation in response to CoCl2.