Nuclear eukaryotic initiation factor 4E (eIF4E) colocalizes with splicing factors in speckles.
Nuclear eukaryotic initiation factor 4E (eIF4E) colocalizes with splicing factors in speckles.
复制标题
核真核起始因子 4E (eIF4E) 与斑点中的剪接因子共定位。
DOI：
10.1083/jcb.148.2.239
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发表时间：
2000-01-24
影响因子：
7.8
通讯作者：
Sonenberg, N
中科院分区：
文献类型：
--
作者：
Dostie, J;Lejbkowicz, F;Sonenberg, N
真核起始因子4E（eIF4E）在蛋白质合成的控制中起着关键作用。eIF4E与mRNA的5′帽结构m7GpppN（其中N为任何核苷酸）结合，并促进核糖体与mRNA的结合。先前已表明，一部分eIF4E定位于细胞核（Lejbkowicz，F.，C. Goyer，A. Darveau，S. Neron，R. Lemieux和N. Sonenberg。1992年，《美国国家科学院院刊》89：9612 - 9616）。在此，我们表明核内的eIF4E存在于整个核质中，但集中在斑点区域。双标记免疫荧光共聚焦显微镜显示eIF4E与Sm和U1snRNP共定位。我们还证明，在细胞透化实验中，帽类似物m7GpppG可使eIF4E从斑点中特异性释放。然而，核糖核酸酶A处理不会使eIF4E从斑点中释放，这表明eIF4E在斑点中的滞留不是由RNA介导的。用5,6 - 二氯 - 1 - β - D - 呋喃核糖基苯并咪唑（DRB）处理细胞会导致eIF4E核斑点凝聚。此外，双特异性激酶Clk/Sty的过表达（而非无催化活性形式）会导致eIF4E核斑点分散。
The eukaryotic initiation factor 4E (eIF4E) plays a pivotal role in the control of protein synthesis. eIF4E binds to the mRNA 5′ cap structure, m7GpppN (where N is any nucleotide) and promotes ribosome binding to the mRNA. It was previously shown that a fraction of eIF4E localizes to the nucleus (Lejbkowicz, F., C. Goyer, A. Darveau, S. Neron, R. Lemieux, and N. Sonenberg. 1992. Proc. Natl. Acad. Sci. USA. 89:9612–9616). Here, we show that the nuclear eIF4E is present throughout the nucleoplasm, but is concentrated in speckled regions. Double label immunofluorescence confocal microscopy shows that eIF4E colocalizes with Sm and U1snRNP. We also demonstrate that eIF4E is specifically released from the speckles by the cap analogue m7GpppG in a cell permeabilization assay. However, eIF4E is not released from the speckles by RNase A treatment, suggesting that retention of eIF4E in the speckles is not RNA-mediated. 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) treatment of cells causes the condensation of eIF4E nuclear speckles. In addition, overexpression of the dual specificity kinase, Clk/Sty, but not of the catalytically inactive form, results in the dispersion of eIF4E nuclear speckles.