Department of Cellular and Molecular Biology, Nicolaus Copernicus Univeristy, Lwowska 1, 87-100, Torun, Poland.
Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wilenska 4, 87-100, Torun, Poland.
Plant J. 2020 Aug;103(3):1155-1173. doi: 10.1111/tpj.14792. Epub 2020 May 28.
In recent years, research has increasingly focused on the key role of post-transcriptional regulation of messenger ribonucleoprotein (mRNP) function and turnover. As a result of the complexity and dynamic nature of mRNPs, the full composition of a single mRNP complex remains unrevealed and mRNPs are poorly described in plants. Here we identify canonical Sm proteins as part of the cytoplasmic mRNP complex, indicating their function in the post-transcriptional regulation of gene expression in plants. Sm proteins comprise an evolutionarily ancient family of small RNA-binding proteins involved in pre-mRNA splicing. The latest research indicates that Sm could also impact on mRNA at subsequent stages of its life cycle. In this work we show that in the microsporocyte cytoplasm of Larix decidua, the European larch, Sm proteins accumulate within distinct cytoplasmic bodies, also containing polyadenylated RNA. To date, several types of cytoplasmic bodies involved in the post-transcriptional regulation of gene expression have been described, mainly in animal cells. Their role and molecular composition in plants remain less well established, however. A total of 222 mRNA transcripts have been identified as cytoplasmic partners for Sm proteins. The specific colocalization of these mRNAs with Sm proteins within cytoplasmic bodies has been confirmed via microscopic analysis. The results from this work support the hypothesis, that evolutionarily conserved Sm proteins have been adapted to perform a whole repertoire of functions related to the post-transcriptional regulation of gene expression in Eukaryota. This adaptation presumably enabled them to coordinate the interdependent processes of splicing element assembly, mRNA maturation and processing, and mRNA translation regulation, and its degradation.
近年来，研究越来越关注信使核糖核蛋白 (mRNP) 功能和周转的转录后调控的关键作用。由于 mRNPs 的复杂性和动态性质，单个 mRNP 复合物的完整组成仍未被揭示，并且 mRNPs 在植物中的描述很差。在这里，我们确定了典型的 Sm 蛋白是细胞质 mRNP 复合物的一部分，这表明它们在植物中转录后基因表达调控中的功能。Sm 蛋白构成了一个进化上古老的小 RNA 结合蛋白家族，参与前体 mRNA 的剪接。最新的研究表明，Sm 也可能在其生命周期的后续阶段影响 mRNA。在这项工作中，我们表明在欧洲落叶松的小孢子细胞质中，Sm 蛋白在包含多聚腺苷酸化 RNA 的不同细胞质体中积累。迄今为止，已经描述了几种参与基因表达转录后调控的细胞质体，主要在动物细胞中。然而，它们在植物中的作用和分子组成仍然不太确定。总共鉴定出 222 个 mRNA 转录本作为 Sm 蛋白的细胞质伴侣。通过显微镜分析证实了这些 mRNA 与 Sm 蛋白在细胞质体中的特异性共定位。这项工作的结果支持了这样的假设，即进化上保守的 Sm 蛋白已经适应了执行与真核生物中转录后基因表达调控相关的整套功能。这种适应可能使它们能够协调剪接元件组装、mRNA 成熟和加工以及 mRNA 翻译调控及其降解的相互依存过程。
