Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koutou 135-0064, Tokyo, Japan.
Front Biosci (Landmark Ed). 2012 Jan 1;17(5):1729-46. doi: 10.2741/4015.
The eukaryotic nucleus is highly compartmentalized, and this structural complexity allows the regulation of complex gene expression pathways. Some of the subnuclear structures called nuclear bodies are known to contain RNAs. Recently multiple noncoding RNAs (ncRNAs) have been identified as products from regions covering large portions of mammalian genomes. Several abundant ncRNAs were found to localize in nuclear bodies, suggesting new roles for ncRNAs in these nuclear bodies. Paraspeckle, one of these nuclear bodies, contains specific ncRNAs, termed MEN (Multiple Endocrine Neoplasia) epsilon/beta ncRNAs, and characteristic RNA-binding proteins. Paraspeckle is ubiquitously observed in cultured cell lines but is cell type-specific in mouse tissues. Paraspeckle reportedly plays an important role in the nuclear retention of inosine-containing mRNAs and is regulated under stress conditions. Intriguingly, MEN epsilon/beta ncRNAs are prerequisite for the formation of paraspeckles, indicating architectural roles for these ncRNAs and, presumably, significant roles in the nuclear retention of mRNAs as well. This review focuses on known aspects of the paraspeckle structure and its components, and we attempt here to construct a model of the ncRNA-dependent formation of nuclear body structures.
真核细胞核高度分隔，这种结构的复杂性允许对复杂的基因表达途径进行调节。一些被称为核小体的亚核结构已知含有 RNA。最近，多种非编码 RNA (ncRNA) 已被鉴定为来自覆盖哺乳动物基因组大部分区域的区域的产物。发现几种丰富的 ncRNA 定位于核小体中，这表明 ncRNA 在这些核小体中具有新的作用。核小体之一的核斑含有特定的 ncRNA，称为 MEN（多发性内分泌肿瘤）epsilon/beta ncRNA 和特征性 RNA 结合蛋白。核斑在培养的细胞系中普遍存在，但在小鼠组织中具有细胞类型特异性。据报道，核斑在肌苷含有 mRNA 的核保留中发挥重要作用，并在应激条件下受到调节。有趣的是，MEN epsilon/beta ncRNA 是核斑形成的必要条件，表明这些 ncRNA 具有结构作用，并且可能在 mRNA 的核保留中也具有重要作用。这篇综述重点介绍了核斑结构及其成分的已知方面，我们试图在这里构建一个依赖 ncRNA 的核体结构形成模型。
