Rathman M, de Lanerolle P, Ohayon H, Gounon P, Sansonetti P
Unité de Pathogénie Microbienne Moléculaire, INSERM U389 and Station Centrale de Microscopie Electronique, Institut Pasteur, 75724 Paris Cedex 15, France.
J Cell Sci. 2000 Oct;113 Pt 19:3375-86. doi: 10.1242/jcs.113.19.3375.
Shigella flexneri, the causitive agent of bacillary dysentery, has been shown to disseminate in colonic epithelial cells via protrusions that extend from infected cells and are endocytosed by adjacent cells. This phenomenon occurs in the region of the eukaryotic cell's adherens junctions and is inhibited by pharmacological reagents or host cell mutations that completely disrupt the junctional complex. In this study, inhibitors of the myosin light chain kinase (MLCK) were shown to dramatically decrease intercellular spread of S. flexneri but to have no inhibitory effect on bacterial entry, multiplication or actin-based motility within the host cell. Furthermore, cell-to-cell spread of Listeria monocytogenes, another bacterial pathogen that uses an actin-based mechanism to move within the eukaryotic cytoplasm and to spread from cell to cell, was not affected by the MLCK inhibitors, indicating that (1) the inhibition of S. flexneri cell-to-cell spread in treated cells is not due to a complete break down of cell-cell contacts, which was subsequently confirmed by confocal microscopy, and (2) MLCK plays a role in a S. flexneri-specific mechanism of dissemination. Myosin has been shown to play a role in a variety of membrane-based phenomena. The work presented here suggests that activation of this molecule via phosphorylation by MLCK, at the very least participates in the formation of the bacteria-containing protrusion, and could also contribute to the endocytosis of this structure by neighboring cells.
弗氏志贺菌是细菌性痢疾的病原体，已证明其可通过从受感染细胞伸出并被相邻细胞内吞的突起在结肠上皮细胞中传播。这种现象发生在真核细胞黏附连接区域，并受到完全破坏连接复合体的药理学试剂或宿主细胞突变的抑制。在本研究中，肌球蛋白轻链激酶（MLCK）抑制剂被证明可显著降低弗氏志贺菌的细胞间传播，但对细菌进入、增殖或在宿主细胞内基于肌动蛋白的运动没有抑制作用。此外，单核细胞增生李斯特菌是另一种利用基于肌动蛋白的机制在真核细胞质内移动并在细胞间传播的细菌病原体，其细胞间传播不受MLCK抑制剂的影响，这表明：（1）经处理的细胞中弗氏志贺菌细胞间传播的抑制并非由于细胞间接触的完全破坏，共聚焦显微镜随后证实了这一点；（2）MLCK在弗氏志贺菌特异性传播机制中发挥作用。肌球蛋白已被证明在多种基于膜的现象中发挥作用。此处呈现的研究结果表明，通过MLCK磷酸化激活该分子，至少参与了含细菌突起的形成，也可能有助于相邻细胞对该结构的内吞作用。
