Li L H, Hui S W
Membrane Biophysics Laboratory, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Biochim Biophys Acta. 1997 Jan 14;1323(1):105-16. doi: 10.1016/s0005-2736(96)00161-7.
The effect of curvature stress on the efficiency of cationic liposome-induced fusion between rabbit erythrocytes was studied. Multilamellar cationic liposomes containing 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP) and different PEs (1,2-dilnoleoyl-sn-glycero-3-phosphoethanolamine (dilin-PE), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), and lysophosphatidylethanolamine, egg (lyso-PE)) were used to induce cell-cell fusion. It was found that high cell-cell fusion yield (FY) of about 50% could be achieved in sucrose solution by using cationic liposomes containing 50% DOTAP. Cell-cell fusion was assayed by shape criterion and was verified by fluorescence microscopy, using a membrane dye mixing method. The curvature stress, as a result of mixing unsaturated PEs in cationic liposomes, had a significant effect on cell-cell FY which increased with the degree of acyl chain unsaturation, in the order dilin-PE > DOPE > POPE > lyso-PE. Replacement of dilin-PE, DOPE, or POPE by lyso-PE gradually in cationic liposomes lowered the cell-cell FY from 50% to 1%. Furthermore, cationic liposome induced cell lysis, and fusion between cationic liposomes and cells, as assayed by the N-(lissamine rhodamine B sulfonyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt and N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2- dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt (Rh-PE/NBD-PE) energy transfer method, followed the same order as that for cell-cell fusion. Fusion between the negatively charged PS liposomes and cationic liposomes also followed the same order. The electric double layer screening by electrolytes in NaCl-containing solution and phosphate buffered saline (PBS) was found to reduce the cell-cell FY and cell lysis. These findings suggest that liposome-induced cell-cell fusion was achieved by cationic liposomes serving as fusion-bridges among cells.
研究了曲率应力对阳离子脂质体诱导兔红细胞间融合效率的影响。使用了含有1,2 - 二油酰基 - 3 - 三甲基铵丙烷（DOTAP）和不同磷脂酰乙醇胺（1,2 - 二亚油酰基 - sn - 甘油 - 3 - 磷酸乙醇胺（二亚油 - PE）、1,2 - 二油酰基 - sn - 甘油 - 3 - 磷酸乙醇胺（DOPE）、1 - 棕榈酰基 - 2 - 油酰基 - sn - 甘油 - 3 - 磷酸乙醇胺（POPE）和蛋黄卵磷脂（溶血 - PE））的多层阳离子脂质体来诱导细胞间融合。发现通过使用含有50% DOTAP的阳离子脂质体，在蔗糖溶液中可实现约50%的高细胞间融合率（FY）。细胞间融合通过形态标准进行测定，并使用膜染料混合法通过荧光显微镜进行验证。由于在阳离子脂质体中混合不饱和磷脂酰乙醇胺而产生的曲率应力，对细胞间FY有显著影响，其随酰基链不饱和程度的增加而增加，顺序为二亚油 - PE > DOPE > POPE > 溶血 - PE。在阳离子脂质体中逐渐用溶血 - PE替代二亚油 - PE、DOPE或POPE会使细胞间FY从50%降至1%。此外，阳离子脂质体诱导细胞裂解，以及通过N -（丽丝胺罗丹明B磺酰基）- 1,2 - 二己酰基 - sn - 甘油 - 3 - 磷酸乙醇胺三乙铵盐和N -（7 - 硝基苯并 - 2 - 恶唑 - 1,3 - 二氮杂 - 4 - 基）- 1,二己酰基 - sn - 甘油 - 3 - 磷酸乙醇胺三乙铵盐（Rh - PE/NBD - PE）能量转移法测定的阳离子脂质体与细胞间的融合，遵循与细胞间融合相同的顺序。带负电荷的PS脂质体与阳离子脂质体之间的融合也遵循相同的顺序。发现在含NaCl溶液和磷酸盐缓冲盐水（PBS）中电解质的双电层筛选会降低细胞间FY和细胞裂解。这些发现表明脂质体诱导的细胞间融合是通过阳离子脂质体作为细胞间的融合桥来实现的。
