Ortega Fabian E, Rengarajan Michelle, Chavez Natalie, Radhakrishnan Prathima, Gloerich Martijn, Bianchini Julie, Siemers Kathleen, Luckett William S, Lauer Peter, Nelson W James, Theriot Julie A
Department of Biochemistry, Stanford University, Stanford, CA 94305.
Department of Biology, Stanford University, Stanford, CA 94305.
Mol Biol Cell. 2017 Nov 1;28(22):2945-2957. doi: 10.1091/mbc.E16-12-0851. Epub 2017 Sep 6.
The intestinal epithelium is the first physiological barrier breached by the Gram-positive facultative pathogen during an in vivo infection. binds to the epithelial host cell receptor E-cadherin, which mediates a physical link between the bacterium and filamentous actin (F-actin). However, the importance of anchoring the bacterium to F-actin through E-cadherin for bacterial invasion has not been tested directly in epithelial cells. Here we demonstrate that depleting αE-catenin, which indirectly links E-cadherin to F-actin, did not decrease invasion of epithelial cells in tissue culture. Instead, invasion increased due to increased bacterial adhesion to epithelial monolayers with compromised cell-cell junctions. Furthermore, expression of a mutant E-cadherin lacking the intracellular domain was sufficient for efficient invasion of epithelial cells. Importantly, direct biotin-mediated binding of bacteria to surface lipids in the plasma membrane of host epithelial cells was sufficient for uptake. Our results indicate that the only requirement for invasion of epithelial cells is adhesion to the host cell surface, and that E-cadherin-mediated coupling of the bacterium to F-actin is not required.
在体内感染过程中，肠道上皮是革兰氏阳性兼性病原菌突破的第一道生理屏障。[病原菌名称]与上皮宿主细胞受体E-钙黏蛋白结合，该受体介导细菌与丝状肌动蛋白（F-肌动蛋白）之间的物理连接。然而，通过E-钙黏蛋白将细菌锚定到F-肌动蛋白上对于细菌入侵上皮细胞的重要性尚未在上皮细胞中直接进行测试。在此，我们证明，减少间接将E-钙黏蛋白与F-肌动蛋白连接的αE-连环蛋白，并不会降低组织培养中上皮细胞的[病原菌名称]入侵。相反，由于细菌对细胞间连接受损的上皮单层的黏附增加，入侵反而增强。此外，缺乏细胞内结构域的突变型E-钙黏蛋白的表达足以实现对上皮细胞的有效[病原菌名称]入侵。重要的是，细菌通过生物素直接介导与宿主上皮细胞质膜表面脂质的结合足以实现摄取。我们的结果表明，上皮细胞入侵的唯一要求是与宿主细胞表面的黏附，并且细菌与F-肌动蛋白的E-钙黏蛋白介导的偶联并非必需。
