Translation of a small subset of Caenorhabditis elegans mRNAs is dependent on a specific eukaryotic translation initiation factor 4E isoform
Translation of a small subset of Caenorhabditis elegans mRNAs is dependent on a specific eukaryotic translation initiation factor 4E isoform
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DOI：
10.1128/mcb.25.1.100-113.2005
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发表时间：
2005-01-01
影响因子：
5.3
通讯作者：
Rhoads, RE
中科院分区：
文献类型：
--
作者：
Dinkova, TD;Keiper, BD;Rhoads, RE
mRNA帽结合蛋白真核翻译起始因子4 E（eIF 4 E）参与蛋白质合成起始、特定mRNA的翻译抑制和核质穿梭。eIF 4 E的多种亚型在多种生物体中表达，但其具体作用知之甚少。我们研究了秀丽隐杆线虫的一种同种型IFE-4，它在植物和哺乳动物中具有同源物。IFE-4：：绿色荧光蛋白（GFP）在咽和尾神经元、体壁肌肉、受精囊和外阴中表达。通过RNA干扰（RNAi）或无效突变敲除ife-4产生包括产卵缺陷的多效性表型。沉降分析表明，IFE-4，而不是IFE-1，是目前在48 S起始复合物，表明它参与蛋白质合成的起始。通过DNA微阵列分析多聚体分布来确定受ife-4敲除影响的mRNA。在没有总mRNA变化的情况下，仅在测试的18，967种秀丽隐杆线虫mRNA中的33种中观察到多核糖体移位，其中不成比例的数量与产卵有关，并在神经元和/或肌肉中表达。翻译调节通过降低的IFN-12、EGL-15和KIN-29水平得到证实。这些蛋白的功能可以解释ife-4基因敲除突变体中观察到的一些表型。这些结果表明，有限的mRNA子集的翻译依赖于eIF 4 E的特定同种型。
The mRNA cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) participates in protein synthesis initiation, translational repression of specific mRNAs, and nucleocytoplasmic shuttling. Multiple isoforms of eIF4E are expressed in a variety of organisms, but their specific roles are poorly understood. We investigated one Caenorhabditis elegans isoform, IFE-4, which has homologues in plants and mammals. IFE-4::green fluorescent protein (GFP) was expressed in pharyngeal and tail neurons, body wall muscle, spermatheca, and vulva. Knockout of ife-4 by RNA interference (RNAi) or a null mutation produced a pleiotropic phenotype that included egg-laying defects. Sedimentation analysis demonstrated that IFE-4, but not IFE-1, was present in 48S initiation complexes, indicating that it participates in protein synthesis initiation. mRNAs affected by ife-4 knockout were determined by DNA microarray analysis of polysomal distribution. Polysome shifts, in the absence of total mRNA changes, were observed for only 33 of the 18,967 C elegans mRNAs tested, of which a disproportionate number were related to egg laying and were expressed in neurons and/or muscle. Translational regulation was confirmed by reduced levels of DAF-12, EGL-15, and KIN-29. The functions of these proteins can explain some phenotypes observed in ife-4 knockout mutants. These results indicate that translation of a limited subset of mRNAs is dependent on a specific isoform of eIF4E.