ERYTHROID CELL-SPECIFIC DETERMINANTS OF ALPHA-GLOBIN MESSENGER-RNA STABILITY
ERYTHROID CELL-SPECIFIC DETERMINANTS OF ALPHA-GLOBIN MESSENGER-RNA STABILITY
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DOI：
10.1128/mcb.14.12.8123
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发表时间：
1994-12-01
影响因子：
5.3
通讯作者：
LIEBHABER, SA
中科院分区：
文献类型：
--
作者：
WEISS, IM;LIEBHABER, SA
尽管珠蛋白 mRNA 被认为是高度稳定信息的原型，但其长寿的机制在很大程度上仍不清楚。作为识别有助于其稳定性的潜在顺式作用元件或结构的第一步，我们分析了天然存在的 α2-珠蛋白突变体 α(Constant Spring) (CS) 的表达缺陷。 CS 突变是翻译终止密码子中的单碱基变化（AA 下的（U）--> AA 下的（C）），允许核糖体通读到 3' 非翻译区 (NTR)。 CS mRNA 在转录活跃的红细胞前体细胞中存在，而在分化程度更高的转录沉默红细胞中不存在（相对于正常的 α-珠蛋白 mRNA），表明这种突变破坏了 α-珠蛋白 mRNA 稳定性所需的某些特征。使用瞬时转染系统，我们证明在小鼠红白血病细胞中，CS mRNA 与正常的 α2-珠蛋白 mRNA 相比不稳定。对小鼠红白血病细胞中其他几种天然存在的定点突变α珠蛋白基因的分析表明，翻译核糖体进入3'NTR的目标是红系细胞中加速降解的信息。相比之下，CS 和 α2-珠蛋白 mRNA 在几种非红系细胞系中都是稳定的。这些结果表明，翻译通读破坏了与 α2-珠蛋白 3' NTR 相关的决定因素，而该决定因素是红细胞中 mRNA 稳定性所必需的。
Although globin mRNAs are considered prototypes of highly stable messages, the mechanisms responsible for their longevity remain largely undefined. As an initial step in identifying potential cis-acting elements or structures which contribute to their stability, we analyzed the defect in expression of a naturally occurring alpha 2-globin mutant, alpha(Constant Spring) (CS). The CS mutation is a single-base change in the translation termination codon ((U) under bar AA-->(C) under bar AA) that allows the ribosome to read through into the 3' nontranslated region (NTR). The presence of CS mRNA in transcriptionally active erythroid precursors and its absence (relative to normal alpha-globin mRNA) in the more differentiated transcriptionally silent erythrocytes suggest that this mutation disrupts some feature of the alpha-globin mRNA required for its stability. Using a transient transfection system, we demonstrate that in murine erythroleukemia cells the CS mRNA is unstable compared with the normal alpha 2-globin mRNA. The analyses of several other naturally occurring and site-directed mutant alpha-globin genes in murine erythroleukemia cells indicate that entry of a translating ribosome into the 3' NTR targets the message for accelerated degradation in erythroid cells. In contrast, both the CS and alpha 2-globin mRNAs are stable in several nonerythroid cell lines. These results suggest that translational readthrough disrupts a determinant associated with the alpha 2-globin 3' NTR which is required for mRNA stability in erythroid cells.