Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion
Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion
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DOI：
10.1194/jlr.m003822
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发表时间：
2010-07-01
影响因子：
6.5
通讯作者：
Sandhoff, Konrad
中科院分区：
文献类型：
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作者：
Abdul-Hammed, Misbaudeen;Breiden, Bernadette;Sandhoff, Konrad
我们研究了尼曼-皮克病2型（NPC 2）蛋白和一些晚期内体脂质[鞘磷脂，神经酰胺和双（单酰基甘油）磷酸盐（BMP）]对胆固醇转移和膜融合的影响。在所有测试的脂质结合蛋白中，只有NPC 2以相当大的速率转移胆固醇，而神经酰胺、GM 3、半乳糖基神经酰胺、硫苷脂、磷脂酰乙醇胺或磷脂酰丝氨酸没有转移。BMP对胆固醇转运有很大的促进作用，神经酰胺对胆固醇转运作用不大，鞘磷脂对胆固醇转运有很强的抑制作用。胆固醇和神经酰胺也显着转移蛋白质的情况下。这种胆固醇的自发转移被神经酰胺大大增强，被BMP轻微增强，被鞘磷脂强烈抑制。在我们的转移试验中，生物素标记的供体脂质体与荧光受体脂质体通过链霉亲和素包被的磁珠分离。因此，荧光的丧失指示膜融合。神经酰胺即使在非常低的浓度下也能诱导脂囊泡的自发融合，而BMP和鞘磷脂分别在约20摩尔%和10摩尔%的浓度下也能诱导脂囊泡的自发融合。除了胆固醇的转移，NPC 2诱导膜融合，虽然低于saposin-C。在此过程中，BMP和神经酰胺分别具有强和弱的刺激作用，而鞘磷脂则具有抑制作用。注意，脂质对由NPC 2介导的胆固醇转移的作用类似于它们对由NPC 2和鞘脂激活蛋白-C诱导的膜融合的作用。Abdul-Hammed，M.，B。布莱登，M. A.阿德巴约巴巴洛拉湾Schwarzmann和K.桑德霍夫内体膜脂质和NPC 2在胆固醇转移和膜融合中的作用。J Lipid Res. 2010. 51：1747-1760。
We examined the effect of Niemann-Pick disease type 2 (NPC2) protein and some late endosomal lipids [sphingomyelin, ceramide and bis(monoacylglycero) phosphate (BMP)] on cholesterol transfer and membrane fusion. Of all lipid-binding proteins tested, only NPC2 transferred cholesterol at a substantial rate, with no transfer of ceramide, GM3, galactosylceramide, sulfatide, phosphatidylethanolamine, or phosphatidylserine. Cholesterol transfer was greatly stimulated by BMP, little by ceramide, and strongly inhibited by sphingomyelin. Cholesterol and ceramide were also significantly transferred in the absence of protein. This spontaneous transfer of cholesterol was greatly enhanced by ceramide, slightly by BMP, and strongly inhibited by sphingomyelin. In our transfer assay, biotinylated donor liposomes were separated from fluorescent acceptor liposomes by streptavidin-coated magnetic beads. Thus, the loss of fluorescence indicated membrane fusion. Ceramide induced spontaneous fusion of lipid vesicles even at very low concentrations, while BMP and sphingomyelin did so at about 20 mol% and 10 mol% concentrations, respectively. In addition to transfer of cholesterol, NPC2 induced membrane fusion, although less than saposin-C. In this process, BMP and ceramide had a strong and mild stimulating effect, and sphingomyelin an inhibiting effect, respectively. Note that the effects of the lipids on cholesterol transfer mediated by NPC2 were similar to their effect on membrane fusion induced by NPC2 and saposin-C.-Abdul-Hammed, M., B. Breiden, M. A. Adebayo, J. O. Babalola, G. Schwarzmann, and K. Sandhoff. Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion. J Lipid Res. 2010. 51: 1747-1760.