The K1 capsule modulates trafficking of E-coli-containing vacuoles and enhances intracellular bacterial survival in human brain microvascular endothelial cells
The K1 capsule modulates trafficking of E-coli-containing vacuoles and enhances intracellular bacterial survival in human brain microvascular endothelial cells
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DOI：
10.1046/j.1462-5822.2003.t01-1-00271.x
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发表时间：
2003-04-01
影响因子：
3.4
通讯作者：
Kim, KS
中科院分区：
文献类型：
--
作者：
Kim, KJ;Elliott, SJ;Kim, KS
大肠杆菌K1在体外可侵入人脑微血管内皮细胞（HBMEC），在体内可转位血脑屏障，但目前尚不清楚大肠杆菌K1是如何侵入的。coliK 1穿过HBMEC。我们以前已经表明，内化E。coli K1定位于HBMEC的膜泡内。本研究旨在了解E. coli K1中的HBMEC中含有空泡（ECVs）。ECV最初获得两种早期内体标记蛋白，EEA 1和转铁蛋白受体。Rab 7和Lamp-1，分别为晚期内体和晚期内体/溶酶体的标志物，随后在ECV上募集，这用ECV的流式细胞术分析证实。然而，即使在孵育120分钟后，ECV也不能获得溶酶体酶组织蛋白酶D，这表明E. coli K1避免了溶酶体融合。与此相反，同基因K1胶囊缺失突变体获得早期和晚期内体标记液泡膜，并允许溶酶体融合，随后降解内空泡。这一观察结果与K1囊缺失突变体细胞内存活率降低一致，尽管突变体的结合率和内化率高于亲本E. coli K1菌株。这是E.大肠杆菌K1通过细菌表面的K1荚膜调节ECV的成熟过程并阻止与溶酶体融合，这是活细菌穿越血脑屏障所必需的事件。
Escherichia coli K1 has been shown to invade human brain microvascular endothelial cells (HBMEC) in vitro and translocate the blood-brain barrier in vivo , but it is unclear how E. coli K1 traverses HBMEC. We have previously shown that internalized E. coli K1 is localized within membrane-bound vacuole in HBMEC. The present study was carried out to understand intracellular trafficking of E. coli K1 containing vacuoles (ECVs) in HBMEC. ECVs initially acquired two early endosomal marker proteins, EEA1 and transferrin receptor. Rab7 and Lamp-1, markers for late endosome and late endosome/lysosome, respectively, were subsequently recruited on the ECVs, which was confirmed with flow cytometry analysis of ECVs. However, ECVs did not obtain cathepsin D, a lysosomal enzyme, even after 120 min incubation, suggesting that E. coli K1 avoids lysosomal fusion. In contrast, isogenic K1 capsule-deletion mutant obtained early and late endosomal markers on vacuolar membranes and allowed lysosomal fusion with subsequent degradation inside vacuoles. This observation was consistent with the decreased intracellular survival of K1 capsule-deletion mutant, even though the binding and internalization rates of the mutant were higher than those of the parent E. coli K1 strain. This is the first demonstration that E. coli K1, via the K1 capsule on the bacterial surface, modulates the maturation process of ECVs and prevents fusion with lysosomes, which is an event necessary for traversal of the blood-brain barrier as live bacteria.