熵驱动的起始与细胞骨架黏弹性在内吞作用中的贡献：一个Onsager变分框架
Entropy-Driven Initiation and Cytoskeletal Viscoelasticity in Endocytosis: An Onsager Variational Framework
- Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
- Zhejiang Key Laboratory of Soft Matter Biomedical Materials, Wenzhou Institute, University of Chinese Academy of Sciences（温州研究院，中国科学院大学，浙江省软物质生物医用材料重点实验室）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究通过Onsager变分框架整合耗尽吸引、配体-受体结合、膜变形和细胞骨架黏弹性，揭示了内吞起始的熵驱动力，并预测了包裹时间与刚度、尺寸窗口的依赖关系。
AI中文摘要：
受体介导的内吞作用要求颗粒在配体-受体结合发生之前接近细胞膜至几纳米范围内。现有的连续介质模型通常从已建立的接触开始，并未明确描述细胞外侧面上的拥挤颗粒如何影响颗粒在膜附近的分布。我们考察熵耗尽力作为这种初始接近的一种可能的非特异性贡献。对于理想耗散剂，Asakura-Osawa排除体积构造在接触前的平面几何中给出了精确的耗尽势。该势和力在排除体积重叠开始时连续消失。这种相互作用在特异性结合之前为膜接近提供了可能的贡献，而其向弯曲包裹几何的扩展需要额外的近似。在一个简化的连续介质模型中，我们结合了耗尽吸引、配体-受体结合、膜变形和细胞骨架黏弹性耗散。黏弹性接触通过遗传积分和标准线性固体来表述。动力学模型给出了完全吞噬的条件性最小配体密度、有限的颗粒尺寸窗口以及依赖于刚度的上限。当稳态半径位于有限正包裹时间域内时，估计的包裹时间在某个半径处取得最小值，该半径随结合能密度的增加而减小。在固定黏度和其他独立参数下，相同的时间近似预测随着细胞刚度增加，包裹变慢。定义尺寸窗口的两个正根在极限参数值处合并，这表征了允许尺寸区间的闭合。耗尽吸引被解释为颗粒-膜关联的一种可能贡献。
英文摘要：
Receptor-mediated endocytosis requires a particle to approach the cell membrane to within a few nanometers before ligand--receptor binding can occur. Existing continuum models often start from an already established contact and do not explicitly describe how crowding particles on the extracellular side influence the distribution of the particle near the membrane. We examine entropic depletion forces as one possible nonspecific contribution to this initial approach. For ideal depletants, the Asakura--Oosawa excluded-volume construction gives an exact depletion potential for the planar geometry before contact. The potential and force vanish continuously at the onset of excluded-volume overlap. This interaction provides a possible contribution to membrane proximity before specific binding, while its extension to curved wrapping geometries requires additional approximation. Within a reduced continuum model, we combine depletion attraction, ligand--receptor binding, membrane deformation, and cytoskeletal viscoelastic dissipation. The viscoelastic contact is formulated through a hereditary integral and a standard linear solid. The kinetic model gives a conditional minimum ligand density for complete engulfment, a finite particle-size window, and a stiffness-dependent upper limit. When the stationary radius lies inside the domain of finite positive wrapping times, the estimated wrapping time has a minimum at a radius that decreases with increasing binding energy density. At fixed viscosity and other independent parameters, the same time approximation predicts slower wrapping as cell stiffness increases. The two positive roots defining the size window merge at a limiting parameter value, which characterizes closure of the admissible size interval. Depletion attraction is interpreted as one possible contribution to particle-membrane association
