Assessment of the Roles of Ordered Lipid Microdomains in Post-Endocytic Trafficking of Glycosyl-Phosphatidylinositol-Anchored Proteins in Mammalian Fibroblasts
Assessment of the Roles of Ordered Lipid Microdomains in Post-Endocytic Trafficking of Glycosyl-Phosphatidylinositol-Anchored Proteins in Mammalian Fibroblasts
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DOI：
10.1111/j.1600-0854.2011.01206.x
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发表时间：
2011-08-01
期刊：
影响因子：
4.5
通讯作者：
Silvius, John R.
中科院分区：
文献类型：
--
作者：
Refaei, Mohammad;Leventis, Rania;Silvius, John R.
我们已经使用人工磷脂酰乙醇胺-聚乙二醇（PE-PEG）锚定的蛋白，纳入活的哺乳动物细胞，以评估先前提出的有序的脂质“筏”结构域的糖基磷脂酰肌醇（GPI）锚定蛋白在CHO和BHK细胞内吞后运输的作用。在CHO细胞中，内吞的PE-PEG蛋白缀合物与内化的GPI锚定的叶酸受体强烈共定位，集中在内体再循环隔室中，而不管PE-PEG“锚”的烃链的结构。然而，内化的PE-PEG蛋白缀合物与长链饱和锚再循环到质膜以缓慢的速率与GPI锚定的叶酸受体测量，而缀合物与短链或不饱和锚再循环以更快的速率类似于所观察到的转铁蛋白受体。这些发现支持该提议（Mayor等人，Cholesterol-dependent retention of GPI-anchored proteins in endosomes. EMBO J 1998; 17：4628-4638），GPI蛋白在CHO细胞中的缓慢再循环依赖于它们对有序脂质结构域的亲和力。在BHK细胞中，具有饱和或不饱和“锚”的内化PE-PEG蛋白缀合物与同时内吞的叶酸受体强烈共定位，并且像叶酸受体一样，逐渐在晚期内体/溶酶体中积累。这些后者的研究结果不支持先前的建议，即GPI蛋白的分选到BHK细胞中的晚期内体取决于它们与脂筏的关联。
We have used artificial phosphatidylethanolamine-polyethylene glycol (PE-PEG)-anchored proteins, incorporated into living mammalian cells, to evaluate previously proposed roles for ordered lipid 'raft' domains in the post-endocytic trafficking of glycosylphosphatidylinositol (GPI)-anchored proteins in CHO and BHK cells. In CHO cells, endocytosed PE-PEG protein conjugates colocalized strongly with the internalized GPI-anchored folate receptor, concentrating in the endosomal recycling compartment, regardless of the structure of the hydrocarbon chains of the PE-PEG 'anchor'. However, internalized PE-PEG protein conjugates with long-chain saturated anchors recycled to the plasma membrane at a slow rate comparable to that measured for the GPI-anchored folate receptor, whereas conjugates with short-chain or unsaturated anchors recycled at a faster rate similar to that observed for the transferrin receptor. These findings support the proposal (Mayor et al. Cholesterol-dependent retention of GPI-anchored proteins in endosomes. EMBO J 1998; 17:4628-4638) that the slow recycling of GPI proteins in CHO cells rests on their affinity for ordered lipid domains. In BHK cells, internalized PE-PEG protein conjugates with either saturated or unsaturated 'anchors' colocalized strongly with simultaneously endocytosed folate receptor and, like the folate receptor, gradually accumulated in late endosomes/lysosomes. These latter findings do not support previous suggestions that the sorting of GPI proteins to late endosomes in BHK cells depends on their association with lipid rafts.