Bullock Simon L, Stauber Michael, Prell Alexander, Hughes Julian R, Ish-Horowicz David, Schmidt-Ott Urs
Cancer Research UK, Developmental Genetics Laboratory, PO Box 123, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Development. 2004 Sep;131(17):4251-61. doi: 10.1242/dev.01289. Epub 2004 Jul 27.
Establishment of segmental pattern in the Drosophila syncytial blastoderm embryo depends on pair-rule transcriptional regulators. mRNA transcripts of pair-rule genes localise to the apical cytoplasm of the blastoderm via a selective dynein-based transport system and signals within their 3'-untranslated regions. However, the functional and evolutionary significance of this process remains unknown. We have analysed subcellular localisation of mRNAs from multiple dipteran species both in situ and by injection into Drosophila embryos. We find that although localisation of wingless transcripts is conserved in Diptera, localisation of even-skipped and hairy pair-rule transcripts is evolutionarily labile and correlates with taxon-specific changes in positioning of nuclei. We show in Drosophila that localised pair-rule transcripts target their proteins in close proximity to the nuclei and increase the reliability of the segmentation process by augmenting gene activity. Our data suggest that mRNA localisation signals in pair-rule transcripts affect nuclear protein uptake and thereby adjust gene activity to a variety of dipteran blastoderm cytoarchitectures.
果蝇合胞体胚盘胚胎中节段模式的建立依赖于成对规则转录调节因子。成对规则基因的mRNA转录本通过基于动力蛋白的选择性运输系统及其3'非翻译区内的信号定位于胚盘的顶端细胞质中。然而，这一过程的功能和进化意义仍不清楚。我们通过原位杂交和注射到果蝇胚胎中的方法，分析了多个双翅目物种mRNA的亚细胞定位。我们发现，尽管无翅转录本的定位在双翅目中是保守的，但偶数缺失和毛状成对规则转录本的定位在进化上是不稳定的，并且与细胞核定位的分类群特异性变化相关。我们在果蝇中表明，定位的成对规则转录本将其蛋白质靶向靠近细胞核的位置，并通过增强基因活性提高了节段化过程的可靠性。我们的数据表明，成对规则转录本中的mRNA定位信号影响核蛋白摄取，从而将基因活性调整为多种双翅目胚盘细胞结构。
