Asymmetric addition of ceramides but not dihydroceramides promotes transbilayer (flip-flop) lipid motion in membranes
Asymmetric addition of ceramides but not dihydroceramides promotes transbilayer (flip-flop) lipid motion in membranes
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DOI：
10.1529/biophysj.104.050690
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发表时间：
2005-01-01
影响因子：
3.4
通讯作者：
Goñi, FM
中科院分区：
文献类型：
--
作者：
Contreras, FX;Basañez, G;Goñi, FM
跨双分子膜脂质运动在某些生理事件中可能是重要的，如神经酰胺信号传导。在这项研究中，使用芘标记的磷脂类似物监测了由神经酰胺添加或酶促神经酰胺生成在膜一侧诱导的脂质跨双层重新分配。当在有机溶液中加入预先形成的脂质体时，蛋神经酰胺以剂量依赖的方式诱导跨双分子层脂质运动。短链（C6和C2）神经酰胺的活性低于鸡蛋神经酰胺，而二氢神经酰胺或二油基甘油在促进人的翻转方面几乎没有活性。当神经酰胺、二氢神经酰胺或二酰基甘油通过鞘磷脂酶或磷脂酶c的作用在原位生成时，也得到了同样的结果（阳性或阴性）。这种现象依赖于双层脂质组成，在促进反向相形成的脂质存在时速度更快，例如磷脂酰乙醇胺和胆固醇；相反，在溶血磷脂酰胆碱的存在下，反应速度会变慢，因为溶血磷脂酰胆碱会抑制反向相的形成。在纯磷脂酰胆碱或纯鞘磷脂组成的双分子层中几乎检测不到跨双分子层运动。pyrenee -磷脂酰丝氨酸的使用允许以与在模型膜中观察到的速率相当的速度检测人红细胞膜中卵细胞神经酰胺诱导的触发器运动。数据表明，当一个膜离开。神经酰胺变得丰富，它们向另一个叶子扩散。这被相反方向的脂质运动抵消，因此避免了单层之间的净质量传递。这些观察结果可能与神经酰胺跨膜信号传导的生理机制有关。
Transbilayer lipid motion in membranes may be important in certain physiological events, such as ceramide signaling. In this study, the transbilayer redistribution of lipids induced either by ceramide addition or by enzymatic ceramide generation at one side of the membrane has been monitored using pyrene-labeled phospholipid analogs. When added in organic solution to preformed liposomes, egg ceramide induced transbilayer lipid motion in a dose-dependent way. Short-chain (C6 and C2) ceramides were less active than egg ceramide, whereas dihydroceramides or dioleoylglycerol were virtually inactive in promoting flip-flop. The same results ( either positive or negative) were obtained when ceramides, dihydroceramides, or diacylglycerols were generated in situ through the action of a sphingomyelinase or of a phospholipase C. The phenomenon was dependent on the bilayer lipid composition, being faster in the presence of lipids that promote inverted phase formation, e. g., phosphatidylethanolamine and cholesterol; and, conversely, slower in the presence of lysophosphatidylcholine, which inhibits inverted phase formation. Transbilayer motion was almost undetectable in bilayers composed of pure phosphatidylcholine or pure sphingomyelin. The use of pyrene-phosphatidylserine allowed detection of flip-flop movement induced by egg ceramide in human red blood cell membranes at a rate comparable to that observed in model membranes. The data suggest that when one membrane lea. et becomes enriched in ceramides, they diffuse toward the other lea. et. This is counterbalanced by lipid movement in the opposite direction, so that net mass transfer between monolayers is avoided. These observations may be relevant to the physiological mechanism of transmembrane signaling via ceramides.