Identification and characterization of an hnRNP E1 translational silencing motif.
Identification and characterization of an hnRNP E1 translational silencing motif.
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DOI：
10.1093/nar/gkw241
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发表时间：
2016-07-08
影响因子：
14.9
通讯作者：
Howe PH
中科院分区：
文献类型：
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作者：
Brown AS;Mohanty BK;Howe PH
非典型转化生长因子β (TGFβ)信号通过蛋白激酶B （Akt2）诱导异质核核糖核蛋白E1 （hnRNP E1）丝氨酸-43 （p-hnRNP E1）磷酸化。这种hnRNP E1的翻译后修饰（PTM）促进其从3 '非翻译区（UTR）核酸调控基序解离，驱动上皮向间质转化（EMT）和转移。我们已经确定了一个hnRNP E1共识结合基序，并在基因组上解决了它所包含的一个基因子集。本研究表征了共识结合基元与hnRNP E1、其各种k -同源（KH）结构域和p-hnRNP E1的结合动力学。p-hnRNP E1水平在转移性癌细胞中高度上调，而在正常上皮组织中较低。我们发现这种PTM与Akt2及其活化形式磷酸化丝氨酸-474 （p-Akt2）水平之间存在相关性。利用转移的细胞进展模型，我们观察到转移细胞中Akt2、p-Akt2和p-hnRNP E1蛋白的高水平表达，以及总hnRNP E1水平的显著降低。被hnRNP E1翻译沉默并通过其解离表达的基因与EMT的进展和转移密切相关。这项研究提供了对非典型TGFβ信号级联的深入了解，该级联负责通过hnRNP E1沉默靶点的异常表达诱导EMT。在细胞模型中，高丰度的p-hnRNP E1和低水平的hnRNP E1清楚地显示了该系统在转移进展中的相关性。这一分子机制的解析提供了新的见解，为治疗干预提供了靶点，并进一步了解了tgf - β微环境的作用。
Non-canonical transforming growth factor β (TGFβ) signaling through protein kinase B (Akt2) induces phosphorylation of heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1) at serine-43 (p-hnRNP E1). This post-translational modification (PTM) of hnRNP E1 promotes its dissociation from a 3′ untranslated region (UTR) nucleic acid regulatory motif, driving epithelial to mesenchymal transition (EMT) and metastasis. We have identified an hnRNP E1 consensus-binding motif and genomically resolved a subset of genes in which it is contained. This study characterizes the binding kinetics of the consensus-binding motif and hnRNP E1, its various K-homology (KH) domains and p-hnRNP E1. Levels of p-hnRNP E1 are highly upregulated in metastatic cancer cells and low in normal epithelial tissue. We show a correlation between this PTM and levels of Akt2 and its activated form, phosphorylated serine-474 (p-Akt2). Using cellular progression models of metastasis, we observed a signature high level of Akt2, p-Akt2 and p-hnRNP E1 protein expression, coupled to a significantly reduced level of total hnRNP E1 in metastatic cells. Genes that are translationally silenced by hnRNP E1 and expressed by its dissociation are highly implicated in the progression of EMT and metastasis. This study provides insight into a non-canonical TGFβ signaling cascade that is responsible for inducing EMT by aberrant expression of hnRNP E1 silenced targets. The relevance of this system in metastatic progression is clearly shown in cellular models by the high abundance of p-hnRNP E1 and low levels of hnRNP E1. New insights provided by the resolution of this molecular mechanism provide targets for therapeutic intervention and give further insight into the role of the TGFβ microenvironment.