Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany.
Icahn School of Medicine Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA.
Nat Commun. 2023 Feb 4;14(1):615. doi: 10.1038/s41467-023-35847-z.
During endocytosis of nanoparticles by cells, the cellular membranes engulf the particles, thereby forming a closed membrane neck that subsequently undergoes fission. For solid nanoparticles, these endocytic processes have been studied in some detail. Recently, such processes have also been found for liquid and condensate droplets, both in vitro and in vivo. These processes start with the spreading of the droplet onto the membrane followed by partial or complete engulfment of the droplet. Here, we use molecular dynamics simulations to study these processes at the nanoscale, for nano-sized droplets and vesicles. For both partial and complete engulfment, we observe two different endocytic pathways. Complete engulfment leads to a closed membrane neck which may be formed in a circular or strongly non-circular manner. A closed circular neck undergoes fission, thereby generating two nested daughter vesicles whereas a non-circular neck hinders the fission process. Likewise, partial engulfment of larger droplets leads to open membrane necks which can again have a circular or non-circular shape. Two key parameters identified here for these endocytic pathways are the transbilayer stress asymmetry of the vesicle membrane and the positive or negative line tension of the membrane-droplet contact line.
在细胞内纳米颗粒的内吞作用过程中，细胞膜会包裹颗粒，从而形成一个封闭的膜颈，随后膜颈会发生分裂。对于固态纳米颗粒，这些内吞过程已经得到了较为详细的研究。最近，人们在体外和体内也发现了这些过程同样适用于液态和凝聚态液滴。这些过程首先是液滴在细胞膜上展开，然后部分或完全包裹液滴。在这里，我们使用分子动力学模拟在纳米尺度上研究纳米级液滴和囊泡的这些过程。对于部分和完全包裹，我们观察到两种不同的内吞途径。完全包裹会导致封闭的膜颈形成，该膜颈可能以圆形或强烈非圆形的方式形成。一个封闭的圆形颈会发生分裂，从而产生两个嵌套的子囊泡，而非圆形的颈会阻碍分裂过程。同样，较大液滴的部分包裹会导致开放的膜颈，这些膜颈也可以是圆形或非圆形的。这里确定的这两种内吞途径的两个关键参数是囊泡膜的跨膜压力不对称和膜-液滴接触线的正或负线张力。
