Université Paris Descartes, Faculté de Médecine Paris Descartes, Paris, F-75006, France; INSERM, U970, Paris Cardiovascular Research Center, Paris, F-75015, France.
Cell Microbiol. 2014 Jun;16(6):878-95. doi: 10.1111/cmi.12248. Epub 2013 Dec 27.
Neisseria meningitidis is a bacterium responsible for severe sepsis and meningitis. Following type IV pilus-mediated adhesion to endothelial cells, bacteria proliferating on the cellular surface trigger a potent cellular response that enhances the ability of adhering bacteria to resist the mechanical forces generated by the blood flow. This response is characterized by the formation of numerous 100 nm wide membrane protrusions morphologically related to filopodia. Here, a high-resolution quantitative live-cell fluorescence microscopy procedure was designed and used to study this process. A farnesylated plasma membrane marker was first detected only a few seconds after bacterial contact, rapidly followed by actin cytoskeleton reorganization and bulk cytoplasm accumulation. The bacterial type IV pili-associated minor pilin PilV is necessary for the initiation of this cascade. Plasma membrane composition is a key factor as cholesterol depletion with methyl-β-cyclodextrin completely blocks the initiation of the cellular response. In contrast membrane deformation does not require the actin cytoskeleton. Strikingly, plasma membrane remodelling undermicrocolonies is also independent of common intracellular signalling pathways as cellular ATP depletion is not inhibitory. This study shows that bacteria-induced plasma membrane reorganization is a rapid event driven by a direct cross-talk between type IV pili and the plasma membrane rather than by the activation of an intracellular signalling pathway that would lead to actin remodelling.
脑膜炎奈瑟菌是一种导致严重败血症和脑膜炎的细菌。在通过 IV 型菌毛介导与内皮细胞黏附后，在细胞表面增殖的细菌会引发强烈的细胞反应，增强黏附细菌抵抗血流产生的机械力的能力。这种反应的特征是形成许多 100nm 宽的膜突起，形态上与丝状伪足有关。在这里，设计并使用了一种高分辨率定量活细胞荧光显微镜程序来研究这个过程。在细菌接触后的几秒钟内，首先检测到了一个法呢基化的质膜标记物，随后迅速发生肌动蛋白细胞骨架重组和大量细胞质积累。细菌 IV 型菌毛相关的次要菌毛 PilV 对于这个级联反应的启动是必要的。质膜组成是一个关键因素，因为用甲基-β-环糊精去除胆固醇会完全阻断细胞反应的启动。相比之下，膜变形不需要肌动蛋白细胞骨架。引人注目的是，微菌落下的质膜重塑也不依赖于常见的细胞内信号通路，因为细胞 ATP 耗竭没有抑制作用。这项研究表明，细菌诱导的质膜重组是一个快速事件，由 IV 型菌毛与质膜之间的直接相互作用驱动，而不是由激活细胞内信号通路导致肌动蛋白重塑。
