Center for Soft Matter Research, Department of Physics, New York University, New York, United States.
Elife. 2019 Nov 26;8:e47533. doi: 10.7554/eLife.47533.
Liquid-liquid phase separation (LLPS) has been recognized as one of the key cellular organizing principles and was shown to be responsible for formation of membrane-less organelles such as nucleoli. Although nucleoli were found to behave like liquid droplets, many ramifications of LLPS including nucleolar dynamics and interactions with the surrounding liquid remain to be revealed. Here, we study the motion of human nucleoli , while monitoring the shape of the nucleolus-nucleoplasm interface. We reveal two types of nucleolar pair dynamics: an unexpected correlated motion prior to coalescence and an independent motion otherwise. This surprising kinetics leads to a nucleolar volume distribution, [Formula: see text], unaccounted for by any current theory. Moreover, we find that nucleolus-nucleoplasm interface is maintained by ATP-dependent processes and susceptible to changes in chromatin transcription and packing. Our results extend and enrich the LLPS framework by showing the impact of the surrounding nucleoplasm on nucleoli in living cells.
液-液相分离（LLPS）已被认为是细胞的主要组织原则之一，其负责形成无膜细胞器，如核仁。尽管核仁表现得像液滴，但 LLPS 的许多分支，包括核仁动力学以及与周围液体的相互作用，仍有待揭示。在这里，我们研究了人核仁的运动，同时监测核仁-核质界面的形状。我们揭示了两种核仁对动力学：在融合之前的出乎意料的相关运动，以及否则的独立运动。这种惊人的动力学导致核仁体积分布，[公式：见文本]，这是任何现有理论都无法解释的。此外，我们发现核仁-核质界面是由 ATP 依赖性过程维持的，并且容易受到染色质转录和包装的变化的影响。我们的结果通过显示周围核质对活细胞中核仁的影响，扩展和丰富了 LLPS 框架。
