Caveolin limits membrane microdomain mobility and integrin-mediated uptake of fibronectin-binding pathogens
Caveolin limits membrane microdomain mobility and integrin-mediated uptake of fibronectin-binding pathogens
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DOI：
10.1242/jcs.064006
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发表时间：
2010-12-15
影响因子：
4
通讯作者：
Hauck, Christof R.
中科院分区：
文献类型：
--
作者：
Hoffmann, Christine;Berking, Anne;Hauck, Christof R.
金黄色葡萄球菌是医院获得性感染的主要原因，其通过纤连蛋白与整合素α 5 β 1结合，这是一个可以促进宿主体内定植的过程。整合素结合诱导肌动蛋白细胞骨架重排，导致S。非专职吞噬细胞吞噬金黄色葡萄球菌。有趣的是，我们发现纤连蛋白结合S。金黄色葡萄球菌引发膜微区组分的重新分布。特别是，神经节苷脂GM 1和GPI连接的蛋白质募集后，整合素β 1的参与，和破坏膜微区阻断细菌的内化。几个膜微区相关蛋白，如flotillin-1和flotillin-2，以及小窝蛋白，被招募到细菌附着的网站。而flotillin-2的显性阴性版本不影响细菌附着或内化，细胞缺陷的小窝蛋白-1（Cav 1（-/-））显示增加的S。金黄色葡萄球菌和其他Fn结合病原体。在Cav 1（-/-）细胞中，细胞相关细菌的膜微区招募没有改变。然而，荧光恢复后的光漂白（FRAP）揭示了增强的流动性的膜微区相关的蛋白质的小窝蛋白-1的情况下。增强膜微区流动性和增加S.金黄色葡萄球菌被野生型小窝蛋白-1的表达所抑制，而不是小窝蛋白-1 G83 S，其在小窝蛋白支架结构域中具有点突变。同样，膜流动性的化学或物理刺激导致S的摄取增加。金黄色。这些结果突出了小窝蛋白-1在膜微区流动性的负调节中的关键作用，从而影响细菌接合的整合素的内吞作用。这一过程可能不仅限制了整合素结合细菌病原体对宿主细胞的侵袭，而且可能与整合素介导的细胞粘附有关。
Staphylococcus aureus, which is a leading cause of hospital-acquired infections, binds via fibronectin to integrin alpha 5 beta 1, a process that can promote host colonization in vivo. Integrin engagement induces actin cytoskeleton rearrangements that result in the uptake of S. aureus by non-professional phagocytic cells. Interestingly, we found that fibronectin-binding S. aureus trigger the redistribution of membrane microdomain components. In particular, ganglioside GM1 and GPI-linked proteins were recruited upon integrin beta 1 engagement, and disruption of membrane microdomains blocked bacterial internalization. Several membrane-microdomain-associated proteins, such as flotillin-1 and flotillin-2, as well as caveolin, were recruited to sites of bacterial attachment. Whereas dominant-negative versions of flotillin-2 did not affect bacterial attachment or internalization, cells deficient for caveolin-1 (Cav1(-/-)) showed increased uptake of S. aureus and other Fn-binding pathogens. Recruitment of membrane microdomains to cell-associated bacteria was unaltered in Cav1(-/-)cells. However, fluorescence recovery after photobleaching (FRAP) revealed an enhanced mobility of membrane-microdomain-associated proteins in the absence of caveolin-1. Enhanced membrane microdomain mobility and increased uptake of S. aureus was repressed by expression of wild-type caveolin-1, but not caveolin-1 G83S, which harbors a point mutation in the caveolin scaffolding domain. Similarly, chemical or physical stimulation of membrane fluidity led to increased uptake of S. aureus. These results highlight a crucial role for caveolin-1 in negative regulation of membrane microdomain mobility, thereby affecting endocytosis of bacteria-engaged integrins. This process might not only limit host cell invasion by integrin-binding bacterial pathogens, but might also be physiologically relevant for integrin-mediated cell adhesion.