ABSTRACT Eukaryotic cells have 2 to 3 discrete nucleoli required for ribosome synthesis. Nucleoli are phase separated nuclear sub-organelles. Here we examined the role of nuclear Lamins and nucleolar factors in modulating the compartmentalization and dynamics of histone 2B (H2B-ECFP) in the nucleolus. Live imaging and Fluorescence Recovery After Photobleaching (FRAP) of labelled H2B, showed that the depletion of Lamin B1, Fibrillarin (FBL) or Nucleostemin (GNL3), enhances H2B-ECFP mobility in the nucleolus. Furthermore, Nucleolin knockdown significantly decreases H2B-ECFP compartmentalization in the nucleolus, while H2B-ECFP residence and mobility in the nucleolus was prolonged upon Nucleolin overexpression. Co-expression of N-terminal and RNA binding domain (RBD) deletion mutants of Nucleolin or inhibiting 45S rRNA synthesis reduces the sequestration of H2B-ECFP in the nucleolus. Taken together, these studies reveal a crucial role of Nucleolin-rRNA complex in modulating the compartmentalization, stability and dynamics of H2B within the nucleolus.

中文翻译：

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核仁素调节核仁中组蛋白 2B-ECFP 的区室化和动力学


摘要 真核细胞具有核糖体合成所需的 2 至 3 个离散的核仁。核仁是相分离的核亚细胞器。在这里，我们研究了核纤层蛋白和核仁因子在调节核仁中组蛋白 2B (H2B-ECFP) 的区室化和动力学中的作用。标记 H2B 的实时成像和光漂白后荧光恢复 (FRAP) 表明，Lamin B1、Fibrillarin (FBL) 或 Nucleostemin (GNL3) 的消耗可增强 H2B-ECFP 在核仁中的迁移率。此外，Nucleolin 敲低显着降低了 H2B-ECFP 在核仁中的区室化，而 Nucleolin 过表达后 H2B-ECFP 在核仁中的停留和移动性延长。 Nucleolin 的 N 端和 RNA 结合域 (RBD) 缺失突变体的共表达或抑制 45S rRNA 合成可减少 H2B-ECFP 在核仁中的隔离。总而言之，这些研究揭示了核仁蛋白-rRNA 复合物在调节核仁内 H2B 的区室化、稳定性和动态方面的关键作用。