Posttranscriptional Destabilization of the Liver-Specific Long Noncoding RNA HULC by the IGF2 mRNA-Binding Protein 1 (IGF2BP1)
Posttranscriptional Destabilization of the Liver-Specific Long Noncoding RNA HULC by the IGF2 mRNA-Binding Protein 1 (IGF2BP1)
复制标题
DOI：
10.1002/hep.26537
复制
发表时间：
2013-11-01
期刊：
影响因子：
13.5
通讯作者：
Diederichs, Sven
中科院分区：
文献类型：
--
作者：
Haemmerle, Monika;Gutschner, Tony;Diederichs, Sven
选择性的长链非编码RNA（lncRNA）已被证明在肿瘤发生中起重要作用。虽然这些转录物的细胞功能可以是多种多样的，但许多lncRNA调节基因表达。相反，控制lncRNA表达的因素在很大程度上仍然未知。在这里，我们研究了RNA结合蛋白对肝癌相关lncRNA HULC（在肝癌中高度上调）表达的影响。首先，我们验证了HULC在人肝细胞癌中的强烈上调。为了阐明HULC表达的转录后调控机制，我们应用RNA亲和纯化方法来鉴定特定的蛋白质相互作用伙伴和潜在的调节剂。该方法鉴定了IGF 2 BPs家族（IGF 2 mRNA结合蛋白）作为HULC的特异性结合伴侣。IGF 2BP 1（也称为IMP 1）的消耗，而不是IGF 2BP 2或IGF 2BP 3的消耗，导致HULC半衰期增加和稳态表达水平升高，表明转录后调节机制。重要的是，HULC代表第一个不稳定的IGF 2BP底物。为了阐明IGF 2BP 1使HULC不稳定的机制，hocT 1蛋白被鉴定为IGF 2BP 1的新型相互作用伴侣。hocT 1是人CCR 4-NOT去腺苷酶复合物的支架，该复合物是细胞质RNA衰变机制的主要组分。事实上，hocT 1的消耗增加了HULC的半衰期和表达。因此，IGF 2BP 1作为衔接蛋白，募集CCR 4-NOT复合物，从而启动lncRNA HULC的降解。结论：我们的发现为lncRNA表达的调控提供了重要的见解，并确定了IGF 2BP 1在RNA代谢中的新功能。（肝病学2013;58：1703-1712）
Selected long noncoding RNAs (lncRNAs) have been shown to play important roles in carcinogenesis. Although the cellular functions of these transcripts can be diverse, many lncRNAs regulate gene expression. In contrast, factors that control the expression of lncRNAs remain largely unknown. Here we investigated the impact of RNA binding proteins on the expression of the liver cancer-associated lncRNA HULC (highly up-regulated in liver cancer). First, we validated the strong up-regulation of HULC in human hepatocellular carcinoma. To elucidate posttranscriptional regulatory mechanisms governing HULC expression, we applied an RNA affinity purification approach to identify specific protein interaction partners and potential regulators. This method identified the family of IGF2BPs (IGF2 mRNA-binding proteins) as specific binding partners of HULC. Depletion of IGF2BP1, also known as IMP1, but not of IGF2BP2 or IGF2BP3, led to an increased HULC half-life and higher steady-state expression levels, indicating a posttranscriptional regulatory mechanism. Importantly, HULC represents the first IGF2BP substrate that is destabilized. To elucidate the mechanism by which IGF2BP1 destabilizes HULC, the CNOT1 protein was identified as a novel interaction partner of IGF2BP1. CNOT1 is the scaffold of the human CCR4-NOT deadenylase complex, a major component of the cytoplasmic RNA decay machinery. Indeed, depletion of CNOT1 increased HULC half-life and expression. Thus, IGF2BP1 acts as an adaptor protein that recruits the CCR4-NOT complex and thereby initiates the degradation of the lncRNA HULC. Conclusion: Our findings provide important insights into the regulation of lncRNA expression and identify a novel function for IGF2BP1 in RNA metabolism. (Hepatology 2013;58:1703-1712)