Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK.
Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
Cell Rep Methods. 2024 Jul 15;4(7):100814. doi: 10.1016/j.crmeth.2024.100814. Epub 2024 Jul 8.
Inorganic polyphosphate (polyP) is a ubiquitous polymer that controls fundamental processes. To overcome the absence of a genetically tractable mammalian model, we developed an inducible mammalian cell line expressing Escherichia coli polyphosphate kinase 1 (EcPPK1). Inducing EcPPK1 expression prompted polyP synthesis, enabling validation of polyP analytical methods. Virtually all newly synthesized polyP accumulates within the nucleus, mainly in the nucleolus. The channeled polyP within the nucleolus results in the redistribution of its markers, leading to altered rRNA processing. Ultrastructural analysis reveals electron-dense polyP structures associated with a hyper-condensed nucleolus resulting from an exacerbation of the liquid-liquid phase separation (LLPS) phenomena controlling this membraneless organelle. The selective accumulation of polyP in the nucleoli could be interpreted as an amplification of polyP channeling to where its physiological function takes place. Indeed, quantitative analysis of several mammalian cell lines confirms that endogenous polyP accumulates within the nucleolus.
无机多聚磷酸盐（polyP）是一种普遍存在的聚合物，控制着基本过程。为了克服缺乏可遗传的哺乳动物模型的问题，我们开发了一种诱导型哺乳动物细胞系，表达大肠杆菌多聚磷酸盐激酶 1（EcPPK1）。诱导 EcPPK1 表达促使 polyP 合成，从而验证了 polyP 分析方法。几乎所有新合成的 polyP 都在核内积累，主要在核仁中。核仁内通道化的 polyP 导致其标记物的重新分布，导致 rRNA 加工改变。超微结构分析显示，电子致密的 polyP 结构与核仁的超浓缩有关，这是由于控制无膜细胞器的液-液相分离（LLPS）现象加剧所致。polyP 在核仁中的选择性积累可以解释为 polyP 通道化的放大，使其生理功能发生在那里。事实上，对几种哺乳动物细胞系的定量分析证实，内源性 polyP 积累在核仁中。
