Acid sphingomyelinase is required for efficient phago-lysosomal fusion
Acid sphingomyelinase is required for efficient phago-lysosomal fusion
复制标题
DOI：
10.1111/j.1462-5822.2008.01169.x
复制
发表时间：
2008-09-01
影响因子：
3.4
通讯作者：
Utermoehlen, Olaf
中科院分区：
文献类型：
--
作者：
Schramm, Michael;Herz, Jasmin;Utermoehlen, Olaf
酸性鞘磷脂酶（ASMase）定位于内体、吞噬体和溶酶体的内腔以及质膜的外小叶，并将鞘磷脂水解为神经酰胺和磷酸胆碱。使用兼性细胞内细菌单核细胞增生李斯特菌，我们表明，吞噬体成熟成吞噬溶酶体严重受损的巨噬细胞遗传缺陷的ASMase。与野生型巨噬细胞不同，含有L。ASMase（-/-）巨噬细胞中的单核细胞增多症对晚期吞噬体标志物甘露糖-6-磷酸受体（M6 PR）和Rab 7保持阳性至少2小时，并且相应地显示溶酶体标志物如溶酶体相关膜蛋白1（Lamp 1）的延迟获得。溶酶体液相标记物转移到含L.单核细胞增生在ASMase（-/-）巨噬细胞中严重受损，并随着货物大小的增加而减少。此外，含L.来自ASMase（-/-）细胞的单核细胞增多症获得了显著更少的杀线粒体蛋白酶组织蛋白酶D、B和L。这项研究的结果表明，ASMase是晚期吞噬体与溶酶体适当融合所必需的，这对于溶酶体抗菌水解酶有效转移到吞噬体中至关重要。
The acid sphingomyelinase (ASMase) localizes to the lumen of endosomes, phagosomes and lysosomes as well as to the outer leaflet of the plasma membrane and hydrolyses sphingomyelin to ceramide and phosphorylcholine. Using the facultative intracellular bacterium Listeria monocytogenes, we show that maturation of phagosomes into phagolysosomes is severely impaired in macrophages genetically deficient for ASMase. Unlike in wild-type macrophages, phagosomes containing L. monocytogenes in ASMase(-/-) macrophages remained positive for the late phagosomal markers mannose-6-phosphate receptor (M6PR) and Rab7 for at least 2 h and, correspondingly, showed delayed acquisition of lysosomal markers like lysosome associated membrane protein 1 (Lamp1). The transfer of lysosomal fluid phase markers into phagosomes containing L. monocytogenes was severely impaired in ASMase(-/-) macrophages and decreased with increasing size of the cargo. Moreover, phagosomes containing L. monocytogenes from ASMase(-/-) cells acquired significantly less listeriocidal proteases cathepsin D, B and L. The results of this study suggest that ASMase is required for the proper fusion of late phagosomes with lysosomes, which is crucial for efficient transfer of lysosomal antibacterial hydrolases into phagosomes.