Modepalli Vengamanaidu, Moran Yehu
Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel.
Genome Biol Evol. 2017 Jun 1;9(6):1547-1560. doi: 10.1093/gbe/evx106.
In bilaterian animals the 3' ends of microRNAs (miRNAs) are frequently modified by tailing and trimming. These modifications affect miRNA-mediated gene regulation by modulating miRNA stability. Here, we analyzed data from three nonbilaterian animals: two cnidarians (Nematostella vectensis and Hydra magnipapillata) and one poriferan (Amphimedon queenslandica). Our analysis revealed that nonbilaterian miRNAs frequently undergo modifications like the bilaterian counterparts: the majority are expressed as different length isoforms and frequent modifications of the 3' end by mono U or mono A tailing are observed. Moreover, as the factors regulating miRNA modifications are largely uncharacterized in nonbilaterian animal phyla, in present study, we investigated the evolution of 3' terminal uridylyl transferases (TUTases) that are known to involved in miRNA 3' nontemplated modifications in Bilateria. Phylogenetic analysis on TUTases showed that TUTase1 and TUTase6 are a result of duplication in bilaterians and that TUTase7 and TUTase4 are the result of a vertebrate-specific duplication. We also find an unexpected number of Drosophila-specific gene duplications and domain losses in most of the investigated gene families. Overall, our findings shed new light on the evolutionary history of TUTases in Metazoa, as they reveal that this core set of enzymes already existed in the last common ancestor of all animals and was probably involved in modifying small RNAs in a similar fashion to its present activity in bilaterians.
在两侧对称动物中，微小RNA（miRNA）的3'末端经常通过加尾和修剪进行修饰。这些修饰通过调节miRNA的稳定性来影响miRNA介导的基因调控。在这里，我们分析了来自三种非两侧对称动物的数据：两种刺胞动物（星状海葵和乳头多管水母）和一种多孔动物（昆士兰双沟藻）。我们的分析表明，非两侧对称动物的miRNA与两侧对称动物的miRNA一样经常发生修饰：大多数以不同长度的异构体形式表达，并且观察到3'末端通过单尿苷或单腺苷加尾频繁修饰。此外，由于在非两侧对称动物门中调节miRNA修饰的因素在很大程度上尚未得到表征，在本研究中，我们研究了3'末端尿苷酰转移酶（TUTase）的进化，已知这些酶参与两侧对称动物中miRNA的3'非模板化修饰。对TUTase的系统发育分析表明，TUTase1和TUTase6是两侧对称动物中基因复制的结果，而TUTase7和TUTase4是脊椎动物特异性复制的结果。我们还在大多数研究的基因家族中发现了数量意外的果蝇特异性基因复制和结构域丢失。总体而言，我们的研究结果为后生动物中TUTase的进化历史提供了新的线索，因为它们揭示了这组核心酶在所有动物的最后一个共同祖先中就已经存在，并且可能以与其在两侧对称动物中目前的活性类似的方式参与修饰小RNA。
