Regulation of internal ribosome entry site-mediated translation by eukaryotic initiation factor-2α phosphorylation and translation of a small upstream open reading frame
Regulation of internal ribosome entry site-mediated translation by eukaryotic initiation factor-2α phosphorylation and translation of a small upstream open reading frame
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DOI：
10.1074/jbc.m109199200
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发表时间：
2002-01-18
影响因子：
4.8
通讯作者：
Hatzoglou, M
中科院分区：
文献类型：
--
作者：
Fernandez, J;Yaman, I;Hatzoglou, M
适应氨基酸缺乏对细胞存活至关重要。在酵母中，这种适应涉及翻译真核起始因子（eIF） 2 α被激酶GCN2磷酸化。这导致转录因子GCN4的翻译增加，这反过来又增加了氨基酸生物合成基因的转录，而此时大多数基因的表达减少。这表明，在哺乳动物细胞的氨基酸饥饿期间，精氨酸/赖氨酸转运蛋白cat-1 mRNA的翻译增加。这种增加需要GCN2对eIF2alpha的磷酸化和转运体mRNA 5'-leader内48个氨基酸的上游开放阅读框（uORF）的翻译。当这个5'-leader被置于双链mRNA表达载体中时，它作为一个内部核糖体进入序列，其调节活性依赖于uORF的翻译。氨基酸饥饿还诱导了含有cat-1 5'-先导子的单顺反子mrna的翻译，其方式依赖于eIF2alpha磷酸化和48个氨基酸的uORF的翻译。这是哺乳动物在氨基酸饥饿期间通过eIF2alpha磷酸化调节内部核糖体进入序列介导的翻译的第一个例子，表明诱导Cat-1蛋白合成的机制是细胞对氨基酸限制的适应性反应的一部分。
Adaptation to amino acid deficiency is critical for cell survival. In yeast, this adaptation involves phosphorylation of the translation eukaryotic initiation factor (eIF) 2alpha by the kinase GCN2. This leads to the increased translation of the transcription factor GCN4, which in turn increases transcription of amino acid biosynthetic genes, at a time when expression of most genes decreases. Here it is shown that translation of the arginine/lysine transporter cat-1 mRNA increases during amino acid starvation of mammalian cells. This increase requires both GCN2 phosphorylation of eIF2alpha and the translation of a 48-amino acid upstream open reading frame (uORF) present within the 5'-leader of the transporter mRNA. When this 5'-leader was placed in a bicistronic mRNA expression vector, it functioned as an internal ribosomal entry sequence and its regulated activity was dependent on uORF translation. Amino acid starvation also induced translation of monocistronic mRNAs containing the cat-1 5'-leader, in a manner dependent on eIF2alpha phosphorylation and translation of the 48-amino acid uORF. This is the first example of mammalian regulation of internal ribosomal entry sequence-mediated translation by eIF2alpha phosphorylation during amino acid starvation, suggesting that the mechanism of induced Cat-1 protein synthesis is part of the adaptive response of cells to amino acid limitation.