Montacié Charlotte, Durut Nathalie, Opsomer Alison, Palm Denise, Comella Pascale, Picart Claire, Carpentier Marie-Christine, Pontvianne Frederic, Carapito Christine, Schleiff Enrico, Sáez-Vásquez Julio
Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique, UMR 5096, Perpignan, France.
Laboratoire Génome et Développement des Plantes, University of Perpignan Via Domitia, UMR 5096, Perpignan, France.
Front Plant Sci. 2017 Oct 20;8:1815. doi: 10.3389/fpls.2017.01815. eCollection 2017.
In all eukaryotic cells, the nucleolus is functionally and structurally linked to rRNA synthesis and ribosome biogenesis. This compartment contains as well factors involved in other cellular activities, but the functional interconnection between non-ribosomal activities and the nucleolus (structure and function) still remains an open question. Here, we report a novel mass spectrometry analysis of isolated nucleoli from plants using the FANoS (Fluorescence Assisted Nucleolus Sorting) strategy. We identified many ribosome biogenesis factors (RBF) and proteins non-related with ribosome biogenesis, in agreement with the recognized multi-functionality of the nucleolus. Interestingly, we found that 26S proteasome subunits localize in the nucleolus and demonstrated that proteasome activity and nucleolus organization are intimately linked to each other. Proteasome subunits form discrete foci in the disorganized nucleolus of plants. protein extracts display reduced proteasome activity compared to WT protein extracts. Remarkably, proteasome activity in is similar to proteasome activity in WT plants treated with proteasome inhibitors (MG132 or ALLN). Finally, we show that MG132 treatment induces disruption of nucleolar structures in WT but not in plants. Altogether, our data suggest a functional interconnection between nucleolus structure and proteasome activity.
在所有真核细胞中，核仁在功能和结构上都与rRNA合成及核糖体生物发生相关联。这个区室还包含参与其他细胞活动的因子，但是非核糖体活动与核仁（结构和功能）之间的功能联系仍然是一个悬而未决的问题。在这里，我们报道了一项使用FANoS（荧光辅助核仁分选）策略对从植物中分离出的核仁进行的新型质谱分析。我们鉴定出了许多核糖体生物发生因子（RBF）以及与核糖体生物发生无关的蛋白质，这与核仁公认的多功能性相符。有趣的是，我们发现26S蛋白酶体亚基定位于核仁，并证明蛋白酶体活性和核仁组织彼此密切相关。蛋白酶体亚基在植物杂乱的核仁中形成离散的焦点。与野生型蛋白质提取物相比，突变体蛋白质提取物显示出降低的蛋白酶体活性。值得注意的是，突变体中的蛋白酶体活性与用蛋白酶体抑制剂（MG132或ALLN）处理的野生型植物中的蛋白酶体活性相似。最后，我们表明MG132处理会诱导野生型植物而非突变体植物的核仁结构破坏。总之，我们的数据表明核仁结构与蛋白酶体活性之间存在功能联系。
