[论文解读] Condensate-mediated shape transformations of cellular membranes by capillary forces

Lukas Hauer, Katharina Sporbeck+6 more|arXiv (Cornell University)|Mar 16, 2026

Lipid Membrane Structure and Behavior被引用 0

一句话总结

论文证明相分离的生物大分子冷凝相在冷凝相-膜界面处引发毛细力，驱动亚稳态的膜形状（管状、片状、杯状），以及由界面张力控制的滞后性；它结合在体植物细胞腔观察、可调界面张力的体外再构成，以及离体数值膜模型来绘制能量景观与转变动力学。

ABSTRACT

Phase-separated biomolecular condensates with liquid-like properties play a key role in the organization and compartmentalization of the intracellular environment. Condensate-mediated capillary forces acting on membranes drive physiologically important reshaping of membrane-bound organelles, such as vacuoles and autophagosomes. Here, we explore condensate-mediated membrane shape transformations. We employ { extit{in planta}} live-cell imaging, an extit{in vitro} reconstitution system with tunable interfacial tension, and computer simulations of an elastic membrane model to describe three morphologies of membrane structures localized at condensate interfaces: tubes, sheets, and cups. We find that the forces associated with high interfacial tension drive the formation of stable sheets, while tubes and cups prevail at lower interfacial tension. We calculate the free energies of each membrane shape and identify the energy barriers that govern the transitions between the shapes. With this approach, we find that shape transformations depend on the history of the interfacial membrane and exhibit a tube-to-cup hysteresis. These findings indicate that temporal control of condensate surface properties can mediate the morphogenesis of cup-like structures in cells, such as the formation of "bulbs" within plant vacuoles. Our results further generalize how the interplay of condensates and membranes contributes to intracellular organization.

研究动机与目标

• 理解 condensate wetting 在细胞液-液界面如何重新塑形膜。
• 定量界面张力如何控制膜形态（管、片、杯）。
• 表征形状转变的能量屏障与亚稳性。
• 区分平衡与非平衡（滞后）对界面膜的影响。
• 将发现转译到潜在的细胞形态发生，例如植物液泡球状化。

提出的方法

• 在植物 Arabidopsis thaliana 的子叶进行原位活细胞成像，观察液-液界面上涂层膜的片状和杯状结构。
• 体外在巨型单层囊泡（GUVs）中使用相分离的聚合物溶液再构成体系，以调控界面张力 Sigma。
• 对粗粒度蒙特卡洛（MC）最小化及对三角网囊泡的MC模拟，计算包含体积-面积比 v 与简化界面张力 sigma 的自由能景观。
• 对变量接触角 theta 的解析测试，以评估能量预测的鲁棒性。
• STED显微镜以解析膜间距并证实双层分离。
• 对体外/自由能差异的解析与数值比较，以及与离体结果的对比。

Figure 1: Condensates within plant vacuoles shape internal membrane structures. (A) Each individual A. thaliana plant can be used to sample multiple developmental stages of their embryos. Each fruit (seed capsule) contains 30-60 seeds (light gray) with a single embryo. (B) Embryo cells (white dashed

实验结果

研究问题

• RQ1 condensate–膜界面毛细力如何将膜形变为管、片、杯？
• RQ2 界面张力 Sigma 如何影响界面形态的稳定性与转变？
• RQ3 管状、片状、杯状形态之间的能量屏障及其如何依赖于 v 与 sigma？
• RQ4 是否存在由于非平衡亚稳性导致的形状转变滞后，及其控制因素？
• RQ5 离体模型是否能再现体外观测，哪些因素解释二者差异？

主要发现

• 在冷凝相界面上的界面膜形成三种形态：管状、片状和杯状，体内外均可观测到。
• 较高的界面张力 Sigma 稳定片状并降低能量屏障，促进管到片的转变；较低的 Sigma 有利于杯状的形成。
• 能量屏障 H1（管→片）和 H2（片→杯）受 sigma 与 v 调控，预测一个包含管、片、杯区域的形态图。
• 形状转变具有滞后性；管到片和片到杯的转变受历史影响，并可由热涨落激活。
• MC 模拟与实验结果显示管更易初步形成，但片通常先于杯；低 Sigma 下杯更可能，高 Sigma 下片更可能。
• 自由能比较表明低 Sigma 时杯能量更低，而高 Sigma 时片在能量上更有利；体外与离散模型在管能量方面存在差异的讨论。

Figure 2: Membrane structures at liquid-liquid interfaces inside GUV. (A) Left, schematics of GUVs (green) cut in half for illustration purposes. The GUV interior is filled with homogeneous dextran/PEG solutions (light magenta). It undergoes phase separation upon hyperosmotic quenching, forming an u