Hypoxia regulates alternative splicing of HIF and non-HIF target genes.
Hypoxia regulates alternative splicing of HIF and non-HIF target genes.
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DOI：
10.1158/1541-7786.mcr-14-0149
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发表时间：
2014-09
期刊：
影响因子：
--
通讯作者：
Hu CJ
中科院分区：
文献类型：
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作者：
Sena JA;Wang L;Heasley LE;Hu CJ
缺氧是许多实体瘤的共同特征。低氧微环境稳定低氧诱导转录因子1α（HIF 1A）和2α（HIF 2 α/EPAS 1）以激活基因转录，从而促进肿瘤细胞存活。大多数人类基因是选择性剪接的，产生编码功能不同蛋白质的RNA同种型。因此，有效的缺氧反应需要增加HIF靶基因表达以及这些HIF依赖性转录物的适当RNA剪接。然而，目前尚不清楚缺氧是否以及如何调节HIF靶点的RNA剪接。本研究探讨了低氧对肝癌细胞中HIF和非HIF靶基因选择性剪接（AS）的影响，并分析了HIF在调节HIF诱导基因AS中的作用。结果表明，缺氧通常促进缺氧诱导的外显子包含，但减少缺氧减少基因的外显子包含。从机制上讲，HIF活性，而不是缺氧本身被发现是必要的，足以增加包括丙酮酸脱氢酶激酶1（PDK 1）的几个HIF靶标的外显子包含。PDK 1剪接报告基因证实HIF的转录激活足以增加PDK 1剪接报告基因的外显子包含。相反，在缺乏内源性HIF靶基因激活的情况下，其他转录因子对PDK 1小基因的转录激活未能改变PDK 1 RNA剪接。
Hypoxia is a common characteristic of many solid tumors. The hypoxic microenvironment stabilizes hypoxia-inducible transcription factor 1α (HIF1A) and 2α (HIF2α/EPAS1) to activate gene transcription, which promotes tumor cell survival. The majority of human genes are alternatively spliced, producing RNA isoforms that code for functionally distinct proteins. Thus, an effective hypoxia response requires increased HIF target gene expression as well as proper RNA splicing of these HIF-dependent transcripts. However, it is unclear if and how hypoxia regulates RNA splicing of HIF targets. This study determined the effects of hypoxia on alternative splicing (AS) of HIF and non-HIF target genes in hepatocellular carcinoma (HCC) cells and characterized the role of HIF in regulating AS of HIF induced genes. The results indicate that hypoxia generally promotes exon inclusion for hypoxia-induced, but reduces exon inclusion for hypoxia reduced genes. Mechanistically, HIF activity, but not hypoxia per se is found to be necessary and sufficient to increase exon inclusion of several HIF targets including pyruvate dehydrogenase kinase 1 (PDK1). PDK1 splicing reporters confirm that transcriptional activation by HIF is sufficient to increase exon inclusion of PDK1 splicing reporter. In contrast, transcriptional activation of a PDK1 minigene by other transcription factors in the absence of endogenous HIF target gene activation fails to alter PDK1 RNA splicing.