Musinova Yana R, Lisitsyna Olga M, Sorokin Dmitry V, Arifulin Eugene A, Smirnova Tatiana A, Zinovkin Roman A, Potashnikova Daria M, Vassetzky Yegor S, Sheval Eugene V
A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow 119992, Russia.
LIA1066 French-Russian Joint Cancer Research Laboratory, Villejuif 94805, France.
J Cell Sci. 2016 Dec 15;129(24):4509-4520. doi: 10.1242/jcs.189142. Epub 2016 Nov 14.
Nuclear bodies are membraneless organelles that play important roles in genome functioning. A specific type of nuclear bodies known as interphase prenucleolar bodies (iPNBs) are formed in the nucleoplasm after hypotonic stress from partially disassembled nucleoli. iPNBs are then disassembled, and the nucleoli are reformed simultaneously. Here, we show that diffusion of B23 molecules (also known as nucleophosmin, NPM1) from iPNBs, but not fusion of iPNBs with the nucleoli, contributes to the transfer of B23 from iPNBs to the nucleoli. Maturation of pre-ribosomal RNAs (rRNAs) and the subsequent outflow of mature rRNAs from iPNBs led to the disassembly of iPNBs. We found that B23 transfer was dependent on the synthesis of pre-rRNA molecules in nucleoli; these pre-rRNA molecules interacted with B23 and led to its accumulation within nucleoli. The transfer of B23 between iPNBs and nucleoli was accomplished through a nucleoplasmic pool of B23, and increased nucleoplasmic B23 content retarded disassembly, whereas B23 depletion accelerated disassembly. Our results suggest that iPNB disassembly and nucleolus assembly might be coupled through RNA-dependent exchange of nucleolar proteins, creating a highly dynamic system with long-distance correlations between spatially distinct processes.
核体是无膜细胞器，在基因组功能中发挥重要作用。一种特定类型的核体，称为间期前核仁体（iPNBs），在低渗应激后由部分解体的核仁在核质中形成。然后iPNBs解体，同时核仁重新形成。在这里，我们表明B23分子（也称为核磷蛋白，NPM1）从iPNBs扩散，而不是iPNBs与核仁融合，有助于B23从iPNBs转移到核仁。前核糖体RNA（rRNA）的成熟以及随后成熟rRNA从iPNBs流出导致iPNBs解体。我们发现B23的转移依赖于核仁中前rRNA分子的合成；这些前rRNA分子与B23相互作用并导致其在核仁内积累。B23在iPNBs和核仁之间的转移是通过B23的核质池完成的，核质中B23含量的增加会延迟解体，而B23的消耗会加速解体。我们的结果表明，iPNB解体和核仁组装可能通过核仁蛋白的RNA依赖性交换耦合，形成一个高度动态的系统，在空间上不同的过程之间存在长距离相关性。
