Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Genetics. 2013 Dec;195(4):1253-64. doi: 10.1534/genetics.113.155036. Epub 2013 Sep 27.
RNA transcripts without obvious coding potential are widespread in many creatures, including the fruit fly, Drosophila melanogaster. Several noncoding RNAs have been identified within the Drosophila bithorax complex. These first appear in blastoderm stage embryos, and their expression patterns indicate that they are transcribed only from active domains of the bithorax complex. It has been suggested that these noncoding RNAs have a role in establishing active domains, perhaps by setting the state of Polycomb Response Elements A comprehensive survey across the proximal half of the bithorax complex has now revealed nine distinct noncoding RNA transcripts, including four within the Ultrabithorax transcription unit. At the blastoderm stage, the noncoding transcripts collectively span ∼75% of the 135 kb surveyed. Recombination-mediated cassette exchange was used to invert the promoter of one of the noncoding RNAs, a 23-kb transcript from the bxd domain of the bithorax complex. The resulting animals fail to make the normal bxd noncoding RNA and show no transcription across the bxd Polycomb Response Element in early embryos. The mutant flies look normal; the regulation of the bxd domain appears unaffected. Thus, the bxd noncoding RNA has no apparent function.
在许多生物中，包括果蝇 Drosophila melanogaster，广泛存在没有明显编码潜力的 RNA 转录本。在果蝇双胸复合体中已经鉴定出几种非编码 RNA。这些非编码 RNA 最初出现在胚胎胚泡阶段，它们的表达模式表明它们仅从双胸复合体的活性区域转录。有人认为这些非编码 RNA 在建立活性区域方面具有作用，也许是通过设置 Polycomb 反应元件的状态。
对双胸复合体近端一半的全面调查现在揭示了九个不同的非编码 RNA 转录本，包括 Ultrabithorax 转录单元内的四个。在胚泡阶段，非编码转录本总共跨越了调查的 135kb 的约 75%。通过重组介导的盒式交换，反转了双胸复合体 bxd 区域的一个非编码 RNA 的启动子，这是一个 23kb 的转录本。由此产生的动物不能产生正常的 bxd 非编码 RNA，并且在早期胚胎中不在 bxd Polycomb 反应元件上进行转录。突变体苍蝇看起来正常；bxd 区域的调节似乎没有受到影响。因此，bxd 非编码 RNA 没有明显的功能。
