Intravesicular Solute Delivery and Surface Area Regulation in Giant Unilamellar Vesicles Driven by Cycles of Osmotic Stresses
Intravesicular Solute Delivery and Surface Area Regulation in Giant Unilamellar Vesicles Driven by Cycles of Osmotic Stresses
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DOI：
10.1021/jacs.3c11679
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发表时间：
2024-01-24
影响因子：
15
通讯作者：
Parikh，Atul N.
中科院分区：
文献类型：
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作者：
Sambre，Pallavi D.;Ho，James C. S.;Parikh，Atul N.
磷脂双分子层是动态的细胞组分，其拓扑结构不断变化，促进广泛多样的生理功能，包括胞内和胞吐作用、细胞分裂和细胞内运输。这些形状的转变消耗能量，而能量总是由蛋白质的活动提供。在这里，我们表明，周期的相反方向的渗透应力-任何蛋白质活性的辅助下-可以诱导明确的巨大单层囊泡的重塑，最低限度地重演的现象表面积稳态和巨胞饮。我们发现，由通货膨胀低渗压力，然后通货膨胀的高渗压力组成的压力周期提示一个精心制作的序列膜形状的变化，最终运输分子货物从外面到囊内环境。最初的渗透性收缩产生微观球形内陷。在随后的膨胀期间，第一亚群为膨胀膜贡献面积，从而提供用于表面积调节和张力稳态的手段。第二个亚群囊泡进入母囊泡的内腔，产生胞饮囊泡。值得注意的是，GUV和子胞饮囊泡之间的溶质浓度梯度产生水流级联，诱导性瞬时穿孔，使芽和GUV内部之间的溶质交换。这导致分子货物穿过膜边界的有效水通量介导的递送。我们的研究结果表明，一个原始的物理机制的通信和运输跨原细胞室驱动的渗透应力。他们还提出了合理的物理途径，为囊内，可能是细胞内，传递离子，溶质，和分子货物刺激的水渗透电流的循环。
Phospholipid bilayers are dynamic cellular components that undergo constant changes in their topology, facilitating a broad diversity of physiological functions including endo- and exocytosis, cell division, and intracellular trafficking. These shape transformations consume energy, supplied invariably by the activity of proteins. Here, we show that cycles of oppositely directed osmotic stresses─unassisted by any protein activity─can induce well-defined remodeling of giant unilamellar vesicles, minimally recapitulating the phenomenologies of surface area homeostasis and macropinocytosis. We find that a stress cycle consisting of deflationary hypertonic stress followed by an inflationary hypotonic one prompts an elaborate sequence of membrane shape changes ultimately transporting molecular cargo from the outside into the intravesicular milieu. The initial osmotic deflation produces microscopic spherical invaginations. During the subsequent inflation, the first subpopulation contributes area to the swelling membrane, thereby providing a means for surface area regulation and tensional homeostasis. The second subpopulation vesiculates into the lumens of the mother vesicles, producing pinocytic vesicles. Remarkably, the gradients of solute concentrations between the GUV and the daughter pinocytic vesicles create cascades of water current, inducing pulsatory transient poration that enable solute exchange between the buds and the GUV interior. This results in an efficient water-flux-mediated delivery of molecular cargo across the membrane boundary. Our findings suggest a primitive physical mechanism for communication and transport across protocellular compartments driven only by osmotic stresses. They also suggest plausible physical routes for intravesicular, and possibly intracellular, delivery of ions, solutes, and molecular cargo stimulated simply by cycles of osmotic currents of water.