Poole Aaron R, Vicino Ian, Adachi Hironori, Yu Yi-Tao, Hebert Michael D
Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.
Department of Biochemistry and Biophysics, The University of Rochester Medical Center, Rochester, NY 14642, USA.
Biol Open. 2017 Sep 15;6(9):1342-1354. doi: 10.1242/bio.028092.
Many ribonucleoproteins (RNPs), which are comprised of noncoding RNA and associated proteins, are involved in essential cellular processes such as translation and pre-mRNA splicing. One class of RNP is the small Cajal body-specific RNP (scaRNP), which contributes to the biogenesis of small nuclear RNPs (snRNPs) that are central components of the spliceosome. Three scaRNAs are internally processed, generating stable nucleolus-enriched RNAs of unknown function. Here, we provide data that show that these RNAs become part of RNPs we term regulatory RNPs (regRNPs). Most modifications within rRNA (predominantly pseudouridylation and ribose 2'--methylation) are conducted by small nucleolar RNPs (snoRNPs), and we provide evidence that the activity of at least some of these snoRNPs is under the control of regRNPs. Because modifications within rRNA can vary in different physiological or pathological situations, rRNA modifications are thought to be the major source of ribosome heterogeneity. Our identification of regRNPs thus provides a potential mechanism for how ribosome heterogeneity may be accomplished. This work also provides additional functional connections between the Cajal body and the nucleolus.
许多核糖核蛋白（RNP）由非编码RNA和相关蛋白质组成，参与诸如翻译和前体mRNA剪接等重要的细胞过程。一类RNP是小卡哈尔体特异性RNP（scaRNP），它有助于小核核糖核蛋白（snRNP）的生物合成，而snRNP是剪接体的核心组成部分。三种小 Cajal 体特异性RNA（scaRNA）在内部进行加工，产生功能未知的稳定的富含核仁的RNA。在这里，我们提供的数据表明，这些RNA成为了我们称为调节性核糖核蛋白（regRNP）的核糖核蛋白的一部分。核糖体RNA（rRNA）中的大多数修饰（主要是假尿苷化和核糖2'-O-甲基化）由小核仁核糖核蛋白（snoRNP）进行，并且我们提供证据表明，其中至少一些snoRNP的活性受regRNP的控制。由于rRNA中的修饰在不同的生理或病理情况下可能会有所不同，因此rRNA修饰被认为是核糖体异质性的主要来源。我们对regRNP的鉴定因此提供了一种关于核糖体异质性如何实现的潜在机制。这项工作还揭示了卡哈尔体与核仁之间额外的功能联系。
