Sulphur starvation induces the expression of microRNA-395 and one of its target genes but in different cell types
Sulphur starvation induces the expression of microRNA-395 and one of its target genes but in different cell types
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DOI：
10.1111/j.1365-313x.2008.03690.x
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发表时间：
2009-01-01
期刊：
影响因子：
7.2
通讯作者：
Dalmay, Tamas
中科院分区：
文献类型：
--
作者：
Kawashima, Cintia Goulart;Yoshimoto, Naoko;Dalmay, Tamas
植物在全球硫循环中起着重要作用，因为它们从环境中吸收硫并将其整合到甲硫氨酸和半胱氨酸中。硫同化途径的若干基因受微小RNA - 395（miR395）调控，而miR395本身是由低硫（-S）环境诱导产生的。在此，我们表明拟南芥的6个miR395基因座被不同程度地诱导。我们发现MIR395基因座在根和叶的维管系统以及根尖中表达。低硫环境在根和叶中对miR395的诱导表明，对于在低硫土壤/培养基中生长的植物来说，miR395从叶到根通过韧皮部的转运不是必需的。我们还证明miR395的诱导受SLIM1控制，SLIM1是硫同化途径中的一个关键转录因子。出乎意料的是，miR395的一个靶基因SULTR2;1的mRNA水平在根中miR395诱导期间大幅增加。我们表明MIR395转录本在维管系统中的空间表达模式似乎与先前报道的SULTR2;1 mRNA的表达模式没有重叠。这些结果说明，在复杂组织中，微小RNA与其靶基因表达水平之间的负向时间相关性并非靶基因验证的必要条件。
Plants play an important role in the global sulphur cycle because they assimilate sulphur from the environment and build it into methionine and cysteine. Several genes of the sulphur assimilation pathway are regulated by microRNA-395 (miR395) that is itself induced by a low-sulphur (-S) environment. Here, we show that the six Arabidopsis miR395 loci are induced differently. We find that MIR395 loci are expressed in the vascular system of roots and leaves and root tips. Induction of miR395 by a -S environment in both roots and leaves suggests that translocation of miR395 from leaves to roots through the phloem is not necessary for plants growing on -S soil/medium. We also demonstrate that induction of miR395 is controlled by SLIM1, a key transcription factor in the sulphur assimilation pathway. Unexpectedly, the mRNA level of a miR395 target gene, SULTR2;1, strongly increases during miR395 induction in roots. We show that the spatial expression pattern of MIR395 transcripts in the vascular system does not appear to overlap with the expression pattern previously reported for SULTR2;1 mRNA. These results illustrate that negative temporal correlation between the expression level of a miRNA and its target gene in a complex tissue cannot be a requirement for target gene validation.