Vesicle fission of giant unilamellar vesicles of liquid-ordered-phase membranes induced by amphiphiles with a single long hydrocarbon chain
Vesicle fission of giant unilamellar vesicles of liquid-ordered-phase membranes induced by amphiphiles with a single long hydrocarbon chain
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DOI：
10.1021/la062078k
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发表时间：
2007-01-16
期刊：
影响因子：
3.9
通讯作者：
Yamazaki, Masahito
中科院分区：
文献类型：
--
作者：
Inaoka, Yasuyuki;Yamazaki, Masahito
囊泡分裂是细胞生物膜的重要过程，但其机制尚不清楚，且存在争议。利用单巨单层囊泡（GUV）方法，我们最近发现低浓度（低于临界胶束浓度（CMC））的溶血磷脂酰胆碱（lyso-PC）诱导二棕榈酰磷脂酰胆碱/胆固醇（6/4）（DPPC/chol（6/4））膜和鞘磷脂/胆固醇（6/4）膜的GUV在液体有序（lo）相中的囊泡分裂。在这份报告中，为了阐明其机制，我们研究了低浓度（远低于其CMC）的其他具有单一长烃链的两亲物（即，单长链两亲物）对DPPC/chol（6/4）GUV的影响以及膜组成对溶血-PC诱导的囊泡分裂的影响。我们发现，低浓度的单一长链两亲物（溶血磷脂酸，辛基葡糖苷，和十二烷基硫酸钠）诱导的形状变化从一个扁长的两个球连接一个非常窄的脖子，表明单一的长链两亲物可以分配到外部单层在LO相的GUV从水溶液。随着单个长链两亲物浓度的增加，它们都诱导DPPC/chol（6/4）GUV的囊泡分裂，超过它们的阈值浓度。为了阐明胆固醇在单个长链两亲物诱导的囊泡分裂中的作用，我们研究了lyso-PC对L-α相中的二油酰-PC（DOPC）/chol（6/4）膜的GUV的影响;没有囊泡分裂发生，表明胆固醇本身在囊泡分裂中没有发挥重要作用。最后，为了阐明在GUV的lo相膜中包含DOPC对DPPC/chol（6/4）GUV的lyso-PC诱导的囊泡分裂的影响，我们研究了低浓度的lyso-PC对DPPC/DOPC/chol膜的GUV的影响。随着膜中DOPC浓度的增加，lyso-PC的阈值浓度增加。当DOPC浓度为30 mol %或更高时，没有囊泡分裂发生。在此基础上，我们提出了一个假说的机制，单一的长链两亲分子诱导囊泡分裂的GUV的一个lo相膜。
Vesicle fissions are very important processes of biomembranes in cells, but their mechanisms are not clear and are controversial. Using the single giant unilamellar vesicle (GUV) method, we recently found that low concentrations (less than the critical micelle concentration (CMC)) of lysophosphatidylcholine (lyso-PC) induced the vesicle fission of GUVs of dipalmitoylphosphatidylcholine/cholesterol(6/4) (DPPC/chol(6/4)) membranes and sphingomyelin/cholesterol membranes (6/4) in the liquid-ordered (lo) phase. In this report, to elucidate its mechanism, we have investigated the effect of low concentrations (much less than their CMC) of other amphiphiles with a single long hydrocarbon chain (i.e., single long chain amphiphiles) on DPPC/chol(6/4) GUVs as well as the effect of the membrane composition on the lyso-PC-induced vesicle fission. We found that low concentrations of single long chain amphiphiles (lyosophosphatidic acid, octylglucoside, and sodium dodecyl sulfate) induced the shape change from a prolate to two spheres connected by a very narrow neck, indicating that the single long chain amphiphiles can be partitioned into the external monolayer in the lo phase of the GUV from the aqueous solution. As the single long chain amphiphile concentrations were increased, all of them induced vesicle fission of DPPC/chol(6/4) GUVs above their threshold concentrations. To elucidate the role of cholesterol in the single long chain amphiphile-induced vesicle fission, we investigated the effect of lyso-PC on GUVs of dioleoyl-PC (DOPC)/chol(6/4) membranes in the L-alpha phase; no vesicle fission occurred, indicating that cholesterol in itself did not play an important role in the vesicle fission. Finally, to elucidate the effect of the inclusion of DOPC in the lo-phase membrane of GUVs on the lyso-PC-induced vesicle fission of the DPPC/chol(6/4) GUV, we investigated the effect of low concentrations of lyso-PC on GUVs of DPPC/DOPC/chol membranes. With an increase in DOPC concentration in the membrane, the threshold concentration of lyso-PC increased. At and above 30 mol % DOPC, no vesicle fission occurred. On the basis of these results, we have proposed a hypothesis of the mechanism of the single long chain amphiphile-induced vesicle fission of a GUV of a lo-phase membrane.