The Splicing Factor FUBP1 Is Required for the Efficient Splicing of Oncogene MDM2 Pre-mRNA
The Splicing Factor FUBP1 Is Required for the Efficient Splicing of Oncogene MDM2 Pre-mRNA
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DOI：
10.1074/jbc.m114.554717
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发表时间：
2014-06-20
影响因子：
4.8
通讯作者：
Chandler, Dawn S.
中科院分区：
文献类型：
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作者：
Jacob, Aishwarya G.;Singh, Ravi K.;Chandler, Dawn S.
癌基因 MDM2 的选择性剪接是细胞响应基因毒性应激而发生的一种现象，也是几种癌症类型的标志，在致癌过程中具有重要意义。然而，调节这种剪接事件的机制仍不清楚。之前，我们发现了 MDM2 中内含子 11 的重要性，它影响损伤响应性 MDM2 小基因的剪接。在这里，我们鉴定了内含子 11 内的离散顺式调控元件，并报告了 FUBP1（远上游元件结合蛋白 1）与这些元件的结合及其在 MDM2 剪接中发挥的作用。 FUBP1 以其在 c-MYC 背景下作为转录因子的致癌作用而闻名，最近被描述为具有剪接抑制功能的剪接调节因子。就 MDM2 而言，我们将 FUBP1 描述为正剪接调节因子。我们观察到，在体外剪接反应中阻断 FUBP1 的功能会导致 MDM2 小基因内含子的剪接效率降低。此外，即使在正常条件下，细胞中 FUBP1 的敲低也会诱导 MDM2-ALT1 的形成，MDM2-ALT1 是 MDM2 的应激诱导剪接变体。这些结果表明 FUBP1 也是一种强正剪接调节因子，通过结合其内含子促进 MDM2 前体 mRNA 的有效剪接。这些发现是第一份描述致癌因子 FUBP1 介导的 MDM2 选择性剪接调节的报告。
Alternative splicing of the oncogene MDM2 is a phenomenon that occurs in cells in response to genotoxic stress and is also a hallmark of several cancer types with important implications in carcinogenesis. However, the mechanisms regulating this splicing event remain unclear. Previously, we uncovered the importance of intron 11 in MDM2 that affects the splicing of a damage-responsive MDM2 minigene. Here, we have identified discrete cis regulatory elements within intron 11 and report the binding of FUBP1 (Far Upstream element-Binding Protein 1) to these elements and the role it plays in MDM2 splicing. Best known for its oncogenic role as a transcription factor in the context of c-MYC, FUBP1 was recently described as a splicing regulator with splicing repressive functions. In the case of MDM2, we describe FUBP1 as a positive splicing regulatory factor. We observed that blocking the function of FUBP1 in in vitro splicing reactions caused a decrease in splicing efficiency of the introns of the MDM2 minigene. Moreover, knockdown of FUBP1 in cells induced the formation of MDM2-ALT1, a stress-induced splice variant of MDM2, even under normal conditions. These results indicate that FUBP1 is also a strong positive splicing regulator that facilitates efficient splicing of the MDM2 pre-mRNA by binding its introns. These findings are the first report describing the regulation of alternative splicing of MDM2 mediated by the oncogenic factor FUBP1.