Khanal Sweta, Zancanela Beatriz Schueng, Peter Jacob Oche, Flynt Alex Sutton
Cellular and Molecular Biology, University of Southern Mississippi, Hattiesburg, MS, United States.
Front Mol Biosci. 2022 Feb 25;9:802814. doi: 10.3389/fmolb.2022.802814. eCollection 2022.
RNAi is an evolutionarily fluid mechanism with dramatically different activities across animal phyla. One major group where there has been little investigation is annelid worms. Here, the small RNAs of the polychaete developmental model are profiled across development. As is seen with nearly all animals, nearly 200 microRNAs were found with 58 high-confidence novel species. Greater miRNA diversity was associated with later stages consistent with differentiation of tissues. Outside miRNA, a distinct composition of other small RNA pathways was found. Unlike many invertebrates, an endogenous siRNA pathway was not observed, indicating pathway loss relative to basal planarians. No processively generated siRNA-class RNAs could be found arising from dsRNA precursors. This has a significant impact on RNAi technology development for this group of animals. Unlike the apparent absence of siRNAs, a significant population of piRNAs was observed. For many piRNAs, phasing and ping-pong biogenesis pathways were identified. Interestingly, piRNAs were found to be highly expressed during early development, suggesting a potential role in regulation in metamorphosis. Critically, the configuration of RNAi factors in is found in other annelids and mollusks, suggesting that similar biology is likely to be present in the wider clade. This study is the first in providing comprehensive analysis of small RNAs in annelids.
RNA干扰是一种进化上灵活多变的机制，在不同动物门类中具有显著不同的活性。一个几乎未被深入研究的主要类群是环节动物。在此，对多毛纲发育模型的小RNA在整个发育过程中的情况进行了分析。正如在几乎所有动物中所看到的那样，发现了近200种微小RNA，其中有58种是高可信度的新物种。更大的微小RNA多样性与后期阶段相关，这与组织分化一致。在微小RNA之外，还发现了其他小RNA途径的独特组成。与许多无脊椎动物不同，未观察到内源性小干扰RNA途径，这表明相对于基础涡虫纲而言该途径有所缺失。未发现由双链RNA前体产生的连续生成的小干扰RNA类RNA。这对这类动物的RNA干扰技术发展具有重大影响。与明显不存在小干扰RNA不同，观察到大量的PIWI相互作用RNA。对于许多PIWI相互作用RNA，确定了相位和乒乓生物合成途径。有趣的是，发现PIWI相互作用RNA在早期发育期间高度表达，这表明其在变态调控中可能发挥作用。至关重要的是，在其他环节动物和软体动物中也发现了RNA干扰因子的这种配置，这表明在更广泛的进化枝中可能存在类似的生物学现象。这项研究首次对环节动物中的小RNA进行了全面分析。
