Sylvestre Julien, Vialette Stéphane, Corral Debrinski Marisol, Jacq Claude
Laboratoire de Génétique Moléculaire, Ecole Normale Supérieure, 46 rue d'Ulm 75230 Paris cedex O5, France.
Genome Biol. 2003;4(7):R44. doi: 10.1186/gb-2003-4-7-r44. Epub 2003 Jun 6.
Subcellular messenger RNA localization is important in most eukaryotic cells, even in unicellular organisms like yeast for which this process has been underestimated. Microarrays are rarely used to study subcellular mRNA localization at whole-genome level, but can be adapted to that purpose. This work focuses on studying the repartition of yeast nuclear transcripts encoding mitochondrial proteins between free cytosolic polysomes and polysomes bound to the mitochondrial outer membrane.
Combining biochemical fractionations with oligonucleotide array analyses permits clustering of genes on the basis of the subcellular sites of their mRNA translation. A large fraction of yeast nuclear transcripts known to encode mitochondrial proteins is found in mitochondrial outer-membrane-bound fractions. These results confirm and extend a previous analysis conducted with partial genomic microarrays. Interesting statistical relations among mRNA localization, gene origin and mRNA lengths were found: longer and older mRNAs are more prone to be localized to the vicinity of mitochondria. These observations are included in a refined model of mitochondrial protein import.
Mitochondrial biogenesis requires concerted expression of the many genes whose products make up the organelle. In the absence of any clear transcriptional program, coordinated mRNA localization could be an important element of the time-course of organelle construction. We have built a 'MitoChip' localization database from our results which allows us to identify interesting genes whose mRNA localization might be essential for mitochondrial biogenesis in most eukaryotic cells. Moreover, many components of the experimental and data-analysis strategy implemented here are of general relevance in global transcription studies.
亚细胞信使核糖核酸（mRNA）定位在大多数真核细胞中很重要，即使在像酵母这样的单细胞生物中也是如此，而这一过程此前一直被低估。微阵列很少用于在全基因组水平上研究亚细胞mRNA定位，但可以适用于此目的。这项工作专注于研究编码线粒体蛋白的酵母核转录本在游离胞质多核糖体和与线粒体外膜结合的多核糖体之间的分布。
将生化分级分离与寡核苷酸阵列分析相结合，能够根据mRNA翻译的亚细胞位点对基因进行聚类。已知编码线粒体蛋白的很大一部分酵母核转录本存在于与线粒体外膜结合的组分中。这些结果证实并扩展了先前使用部分基因组微阵列进行的分析。发现了mRNA定位、基因起源和mRNA长度之间有趣的统计关系：更长和更古老的mRNA更容易定位于线粒体附近。这些观察结果被纳入了一个改进的线粒体蛋白导入模型。
线粒体生物发生需要许多基因的协同表达，这些基因的产物构成了该细胞器。在没有任何明确转录程序的情况下，协调的mRNA定位可能是细胞器构建时间进程中的一个重要因素。我们根据研究结果建立了一个“线粒体芯片”定位数据库，这使我们能够识别出有趣的基因，其mRNA定位可能对大多数真核细胞中的线粒体生物发生至关重要。此外，这里实施的实验和数据分析策略的许多组成部分在全球转录研究中具有普遍相关性。
