The life of an mRNA in space and time
The life of an mRNA in space and time
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DOI：
10.1242/jcs.062638
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发表时间：
2010-05-15
影响因子：
4
通讯作者：
Shav-Tal, Yaron
中科院分区：
文献类型：
--
作者：
Ben-Ari, Ya'ara;Brody, Yehuda;Shav-Tal, Yaron
核转录基因产生的mRNA转录本注定要从转录位点转运到细胞质中进行蛋白质翻译。某些转录本可进一步定位到特定的细胞质区域。我们在一个能够在体内检测基因位点、转录的mRNA以及整合到肌动蛋白细胞骨架中的细胞质β - 肌动蛋白的细胞系统中，研究了转录的β - 肌动蛋白mRNA在整个基因表达和定位过程中的生命周期。定量分析表明，RNA聚合酶II的延伸速度为3.3 kb/分钟，反式激活因子与启动子的结合是短暂的（40秒），并展示了转录位点内整合基因的编码区和非编码区独特的空间结构。在间期和有丝分裂后测量了基因诱导的速率，表明子细胞在研究基因的转录起始方面并不同步。对核质和细胞质mRNA转运的时空动力学比较表明，β - 肌动蛋白定位反应是从现有的细胞质mRNA库启动的，而不是从基因诱导后新合成的转录本启动的。还证明了随机运动机制在介导真核细胞中mRNA的有效转运方面占主导地位。
Nuclear transcribed genes produce mRNA transcripts destined to travel from the site of transcription to the cytoplasm for protein translation. Certain transcripts can be further localized to specific cytoplasmic regions. We examined the life cycle of a transcribed beta-actin mRNA throughout gene expression and localization, in a cell system that allows the in vivo detection of the gene locus, the transcribed mRNAs and the cytoplasmic beta-actin protein that integrates into the actin cytoskeleton. Quantification showed that RNA polymerase II elongation progressed at a rate of 3.3 kb/minute and that transactivator binding to the promoter was transient (40 seconds), and demonstrated the unique spatial structure of the coding and non-coding regions of the integrated gene within the transcription site. The rates of gene induction were measured during interphase and after mitosis, demonstrating that daughter cells were not synchronized in respect to transcription initiation of the studied gene. Comparison of the spatial and temporal kinetics of nucleoplasmic and cytoplasmic mRNA transport showed that the beta-actin-localization response initiates from the existing cytoplasmic mRNA pool and not from the newly synthesized transcripts arising after gene induction. It was also demonstrated that mechanisms of random movement were predominant in mediating the efficient translocation of mRNA in the eukaryotic cell.