Li Y, Strabala T J, Hagen G, Guilfoyle T J
Department of Biochemistry, University of Missouri, Columbia 65211.
Plant Mol Biol. 1994 Mar;24(5):715-23. doi: 10.1007/BF00029853.
Little is known about how mRNA stability is regulated in higher plants. The SAURs (Small Auxin-Up RNAs) are a family of highly unstable mRNAs in soybean that rapidly increase in abundance after excised organs are treated with the plant hormone auxin. The SAURs are also induced by protein synthesis inhibitors, including cycloheximide, in the absence of auxin treatment and are superinduced when organs are treated with cycloheximide plus auxin. While the induction of SAURs is transcriptionally regulated by auxin, the induction by cycloheximide is posttranscriptional. Cycloheximide as well as other protein synthesis inhibitors appear to induce SAUR accumulation by increasing the stabilities of these mRNAs. To determine whether the 5'-untranslated region, the 3'-untranslated region, or the open reading frame of these unstable mRNAs is responsible for the cycloheximide inducibility, we have used chimeric genes in transgenic tobacco plants to test each of these mRNA regions. Our results show that the SAUR open reading frame within a chimeric mRNA confers cycloheximide inducibility in transgenic tobacco plants whereas chimeric mRNAs containing the SAUR 5'-untranslated region or 3'-untranslated region as isolated elements or in combination are not induced by cycloheximide. These results suggest that the SAUR open reading frame contains sequence elements that are involved in the stability of these mRNAs.
关于高等植物中mRNA稳定性是如何调控的，目前所知甚少。SAURs（小生长素上调RNA）是大豆中一类高度不稳定的mRNA，在离体器官用植物激素生长素处理后，其丰度会迅速增加。在没有生长素处理的情况下，SAURs也会被包括环己酰亚胺在内的蛋白质合成抑制剂诱导，并且当器官用环己酰亚胺加生长素处理时会被超诱导。虽然SAURs的诱导受生长素的转录调控，但环己酰亚胺的诱导是转录后调控。环己酰亚胺以及其他蛋白质合成抑制剂似乎通过增加这些mRNA的稳定性来诱导SAUR的积累。为了确定这些不稳定mRNA的5'非翻译区、3'非翻译区或开放阅读框是否对环己酰亚胺诱导性负责，我们在转基因烟草植物中使用嵌合基因来测试这些mRNA区域中的每一个。我们的结果表明，嵌合mRNA中的SAUR开放阅读框赋予转基因烟草植物环己酰亚胺诱导性，而含有SAUR 5'非翻译区或3'非翻译区作为分离元件或组合的嵌合mRNA不会被环己酰亚胺诱导。这些结果表明，SAUR开放阅读框包含参与这些mRNA稳定性的序列元件。
