Quah Shan, Hui Jerome H L, Holland Peter W H
Department of Zoology, University of Oxford.
Department of Zoology, University of Oxford
Mol Biol Evol. 2015 May;32(5):1161-74. doi: 10.1093/molbev/msv004. Epub 2015 Jan 8.
MicroRNAs (miRNAs) are involved in posttranscriptional regulation of gene expression. Because several miRNAs are known to affect the stability or translation of developmental regulatory genes, the origin of novel miRNAs may have contributed to the evolution of developmental processes and morphology. Lepidoptera (butterflies and moths) is a species-rich clade with a well-established phylogeny and abundant genomic resources, thereby representing an ideal system in which to study miRNA evolution. We sequenced small RNA libraries from developmental stages of two divergent lepidopterans, Cameraria ohridella (Horse chestnut Leafminer) and Pararge aegeria (Speckled Wood butterfly), discovering 90 and 81 conserved miRNAs, respectively, and many species-specific miRNA sequences. Mapping miRNAs onto the lepidopteran phylogeny reveals rapid miRNA turnover and an episode of miRNA fixation early in lepidopteran evolution, implying that miRNA acquisition accompanied the early radiation of the Lepidoptera. One lepidopteran-specific miRNA gene, miR-2768, is located within an intron of the homeobox gene invected, involved in insect segmental and wing patterning. We identified cubitus interruptus (ci) as a likely direct target of miR-2768, and validated this suppression using a luciferase assay system. We propose a model by which miR-2768 modulates expression of ci in the segmentation pathway and in patterning of lepidopteran wing primordia.
微小RNA(miRNA)参与基因表达的转录后调控。由于已知几种miRNA会影响发育调控基因的稳定性或翻译,新型miRNA的起源可能促进了发育过程和形态的进化。鳞翅目(蝴蝶和蛾类)是一个物种丰富的类群,具有完善的系统发育和丰富的基因组资源,因此是研究miRNA进化的理想系统。我们对两种不同鳞翅目昆虫——栎绿卷蛾(栗叶潜叶蛾)和眼蝶(斑点木蝴蝶)发育阶段的小RNA文库进行了测序,分别发现了90个和81个保守的miRNA以及许多物种特异性的miRNA序列。将miRNA映射到鳞翅目系统发育树上,揭示了miRNA的快速更替以及在鳞翅目进化早期的一次miRNA固定事件,这意味着miRNA的获得伴随着鳞翅目的早期辐射。一个鳞翅目特异性的miRNA基因miR - 2768位于同源异型框基因invected的一个内含子中,该基因参与昆虫的体节和翅膀图案形成。我们确定了patched(ci)是miR - 2768可能的直接靶标,并使用荧光素酶检测系统验证了这种抑制作用。我们提出了一个模型,通过该模型miR - 2768在鳞翅目体节形成途径和翅膀原基图案形成中调节ci的表达。