脂质筏——病原微生物出入细胞的一种门户

Lipid raft-a gateway for passing through the cell membrane for pathogens

脂质筏是富含胆固醇和鞘磷脂的一种特殊膜结构,脂质筏形成的膜微区具有更低的膜流动性,呈现有序液相。脂质筏参与包括跨膜信号转导、物质内吞、脂质及蛋白定向分选在内的多种重要细胞生物学过程。分布于脂筏的分子主要有两种形式的蛋白修饰:与糖基磷脂酰肌醇(GPI)相连,或被肉豆蔻酸酰化/软脂酸酯酰化。一系列GPI-锚固蛋白被鉴定为多种不同的细菌、细菌毒素和病毒的受体。越来越多的研究发现,不同类型和种属来源的细菌、细菌毒素、原虫及病毒利用细胞质膜表面的脂筏结构介导其入胞,完成跨细胞转运、胞内复制或感染周期,一些病毒还利用脂筏完成其病毒颗粒的组装和出芽过程。通过对病原微生物如何利用脂筏介导其内吞及内吞入胞后在胞内的转运的研究,有利于我们更好地认识病原微生物与宿主细胞之间的相互作用,从而有可能发展更有效的抗感染策略。

Lipid rafts are membrane structure enriched in cholesterol and sphingolipids, and form liquid ordereddomains of decreased membrane fluidity. Lipid rafts play important roles in many biological processes includ-ing transmembrane signal transduction, endocytosis, lipid and protein sorting, and so on. Two principal pro-teins modifications are found in lipid rafts: one is covalent binding to glycosyl-phosphatidylinositol (GPI), theother is myristoylization. A series of GPI-anchored proteins are identified as receptors of many different patho-gen organisms. Increasing amount of reports demonstrate that many pathogens (bacteria, parasites, and viruses)and toxins preferentially utilize rafts for interacting with their target cells, entry, replication and infection. Also,the lipid raft domains provide sites for assembly and budding of certain viruses. The progress in understandingthe roles of lipid rafts in pathogen infections may facilitate the development of new strategies for anti-infections.