Quantitative analysis of multilayer organization of proteins and RNA in nuclear speckles at super resolution
Quantitative analysis of multilayer organization of proteins and RNA in nuclear speckles at super resolution
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DOI：
10.1242/jcs.206854
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发表时间：
2017-12-01
影响因子：
4
通讯作者：
Ha, Taekjip
中科院分区：
文献类型：
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作者：
Fei, Jingyi;Jadaliha, Mahdieh;Ha, Taekjip
核斑是由rna和蛋白质组成的自组装细胞器。它们被认为是控制基因表达不同步骤的结构域，包括转录、剪接和mRNA输出。早期的研究发现了斑点中一些成分的不同定位。据推测，散斑成分的空间组织可能直接有助于协调不同过程的操作顺序。在这里，通过执行多色结构照明显微镜，我们以更高的分辨率表征了斑点的多层组织。我们发现SON和SC35（也称为asSRSF2）定位于斑点的中心区域，而MALAT1和小核（sn） rna富集于斑点的外围。粗粒度模拟表明，非随机组织的产生是由于有利的序列编码的斑点驻留蛋白和rna的分子间相互作用之间的相互作用。最后，我们观察到斑点内存在的RNA总量与斑点大小呈正相关。这些结果暗示斑点的大小可能被调节以适应RNA的积累和加工。来自各种活跃转录的斑点相关基因的RNA的积累可能有助于在单个细胞内观察到的斑点大小变化。
Nuclear speckles are self-assembled organelles composed of RNAs and proteins. They are proposed to act as structural domains that control distinct steps in gene expression, including transcription, splicing and mRNA export. Earlier studies identified differential localization of a few components within the speckles. It was speculated that the spatial organization of speckle components might contribute directly to the order of operations that coordinate distinct processes. Here, by performing multi-color structured illumination microscopy, we characterized the multilayer organization of speckles at a higher resolution. We found that SON and SC35 (also known asSRSF2) localize to the central region of the speckle, whereas MALAT1 and small nuclear (sn)RNAs are enriched at the speckle periphery. Coarse-grained simulations indicate that the non-random organization arises due to the interplay between favorable sequence-encoded intermolecular interactions of speckle-resident proteins and RNAs. Finally, we observe positive correlation between the total amount of RNA present within a speckle and the speckle size. These results imply that speckle sizemay be regulated to accommodate RNA accumulation and processing. Accumulation of RNA from various actively transcribed speckle-associated genes could contribute to the observed speckle size variations within a single cell.