Sequential protein secretion from three distinct organelles of Toxoplasma gondii accompanies invasion of human fibroblasts.
Sequential protein secretion from three distinct organelles of Toxoplasma gondii accompanies invasion of human fibroblasts.
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发表时间：
1997
影响因子：
6.6
通讯作者：
V. Carruthers;L. Sibley
中科院分区：
文献类型：
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作者：
V. Carruthers;L. Sibley
原生动物弓形虫对脊椎动物细胞的入侵伴随着三种不同寄生虫细胞器（称为微线体、棒状体和致密颗粒）的受调节蛋白质分泌。我们使用免疫荧光、免疫电子显微镜和定量免疫分析比较了宿主细胞侵袭过程中这些不同区室的分泌动力学。与宿主细胞的结合触发了微线蛋白 MIC2 在寄生虫和宿主细胞之间形成的紧密附着区的顶端释放。第二步，通过释放棒状体蛋白 ROP1 来引发宿主细胞质膜的内陷，形成新生的寄生液泡 (PV)。当入侵完成时，ROP1 已完全排入液泡。与这些非常快速的早期事件相反，致密颗粒标记物 GRA1 和 NTPase 的释放被延迟，直到寄生虫完全进入 PV 后，最终在入侵后 20 分钟达到峰值。不同细胞器分泌的顺序触发意味着它们的释放是由单独的信号控制的，并且它们的内容物介导细胞内寄生的不同阶段。
Invasion of vertebrate cells by the protozoan Toxoplasma gondii is accompanied by regulated protein secretion from three distinct parasite organelles called micronemes, rhoptries, and dense granules. We have compared the kinetics of secretion from these different compartments during host cell invasion using immunofluorescence, immunoelectron microscopy, and quantitative immunoassays. Binding to the host cell triggered apical release of the micronemal protein MIC2 at the tight attachment zone that forms between the parasite and the host cell. In a second step, invagination of the host cell plasma membrane was initiated by discharge of the rhoptry protein ROP1 to form a nascent parasitophorous vacuole (PV). ROP1 was fully discharged into the vacuole by the time invasion was complete. In contrast to these very rapid early events, release of the dense granule markers GRA1 and NTPase was delayed until after the parasite was fully within the PV, eventually peaking at 20 min post-invasion. The sequential triggering of secretion from different organelles implies that their release is governed by separate signals and that their contents mediate distinct phases of intracellular parasitism.