Rodriguez N, Heuvingh J, Pincet F, Cribier S
Laboratoire de Physico-Chimie Moléculaire des Membranes Biologiques, UMR7099, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
Biochim Biophys Acta. 2005 Aug 5;1724(3):281-7. doi: 10.1016/j.bbagen.2005.04.028.
Formation of pore-like structures in cell membranes could participate in exchange of matter between cell compartments and modify the lipid distribution between the leaflets of a bilayer. We present experiments on two model systems in which major lipid redistribution is attributed to few submicroscopic transient pores. The first kind of experiments consists in destabilizing the membrane of a giant unilamellar vesicle by inserting conic-shaped fluorescent lipids from the outer medium. The inserted lipids (10% of the vesicle lipids) should lead to membrane rupture if segregated on the outer leaflet. We show that a 5-nm diameter pore is sufficient to ease the stress on the membrane by redistributing the lipids. The second kind of experiments consists in forcing giant vesicles containing functionalized lipids to adhere. This adhesion leads to hemifusion (merging of the outer leaflets). In certain cases, the formation of pores in one of the vesicles is attested by contrast loss on this vesicle and redistribution of fluorescent labels between the leaflets. The kinetics of these phenomena is compatible with transient submicroscopic pores and long-lived membrane defects.
细胞膜中孔状结构的形成可能参与细胞区室之间的物质交换，并改变双层膜小叶之间的脂质分布。我们展示了在两个模型系统上进行的实验，其中主要的脂质重新分布归因于少数亚微观瞬态孔。第一种实验是通过从外部介质中插入锥形荧光脂质来破坏巨型单层囊泡的膜。如果插入的脂质（占囊泡脂质的10%）在外小叶上分离，应该会导致膜破裂。我们表明，直径为5纳米的孔足以通过重新分布脂质来缓解膜上的应力。第二种实验是迫使含有功能化脂质的巨型囊泡粘附。这种粘附会导致半融合（外小叶融合）。在某些情况下，其中一个囊泡中孔的形成通过该囊泡上的对比度损失以及荧光标记在小叶之间的重新分布得到证实。这些现象的动力学与瞬态亚微观孔和长寿命膜缺陷相符。
