Bailey A L, Cullis P R
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
Biochemistry. 1997 Feb 18;36(7):1628-34. doi: 10.1021/bi961173x.
Determination of the mechanisms by which cationic liposomes adhere to and fuse with biological membranes is important to understanding how these lipid vesicles mediate cellular transfection. To determine what role the lipid composition of "target" membranes might have in promoting fusion with cationic liposomes, we have examined the ability of large unilamellar vesicles composed of 1,2-dioleoylsn-phosphatidylethanolamine (DOPE) and N,N-dimethyl-N,N-di-9-cis-octadecenylammonium chloride (DODAC) (1:1) to fuse with target liposomes of varying composition in the absence of DNA. Membrane fusion was promoted by increased negative surface charge and, for liquid crystalline lipids, by increased acyl chain unsaturation in target liposomes. However, the presence of disaturated phospholipids promoted fusion below the gel to liquid crystalline transition temperature, an effect which was eliminated by the addition of cholesterol. It was also shown that DOPE/DODAC (1:1) LUVs fused with erythrocyte ghosts and that this fusion was blocked by the presence of serum. Membrane fusion was determined by a quantitative fluorescent lipid mixing assay and qualitatively by freeze-fracture electron microscopy and fluorescence microscopy.
确定阳离子脂质体与生物膜粘附并融合的机制对于理解这些脂质囊泡如何介导细胞转染至关重要。为了确定“靶”膜的脂质组成在促进与阳离子脂质体融合中可能起的作用，我们研究了由1,2 - 二油酰 - sn - 磷脂酰乙醇胺（DOPE）和N,N - 二甲基 - N,N - 二 - 9 - 顺式 - 十八碳烯基氯化铵（DODAC）（1:1）组成的大单层囊泡在无DNA情况下与不同组成的靶脂质体融合的能力。膜融合通过增加表面负电荷来促进，对于液晶脂质，通过增加靶脂质体中酰基链的不饱和度来促进。然而，二饱和磷脂的存在在低于凝胶到液晶转变温度时促进融合，加入胆固醇可消除这种效应。还表明DOPE/DODAC（1:1）大单层囊泡与红细胞影融合，并且这种融合被血清的存在所阻断。通过定量荧光脂质混合测定法确定膜融合，并通过冷冻断裂电子显微镜和荧光显微镜进行定性分析。
