Toxoplasma proteins GRA17 and GRA23 mediate the movement of small molecules between the host and the parasitophorous vacuole.

Purpose: Two secreted Toxoplasma proteins (GRA17 and GRA23) mediate the passage of small molecules between the host cytoplasm and the parasite-containing vacuole. This provides the first molecular explanation to how intracellular, vacuole-residing parasites in the phylum Apicomplexa, like Plasmodium, gain access to host nutrients. Methods: Mouse-derived Bone Marrow Macrophages were infected with Toxoplasma tachyzoites of either WT, dGRA17, dGRA23, or dGRA17rescue genetic background for 4 hours. Results: GRA23 gene expression levels are elevated in the dGRA17 strain but not vice versa. Conclusions: GRA17 and GRA23 are synergistically required for permeability of small molecules into the Toxoplasma parasitophorous vacuole. Overall design: Toxoplasma and Mouse gene expression profiles from BMDMs infected with either WT (control), dGRA17, gGRA23, or dGRA17rescue (control) tachyzoites were obtained by RNA-Seq on an Illumina HiSeq2000 instruments at 4 hours post-infection.

研究目的：两种分泌型刚地弓形虫（Toxoplasma）蛋白GRA17与GRA23可介导小分子在宿主细胞质与寄生虫寄生液泡（parasitophorous vacuole）之间的跨膜转运。本研究为阐明顶复门（Apicomplexa）内以液泡为栖息位点的胞内寄生虫（如疟原虫属Plasmodium）如何获取宿主营养物质提供了首个分子层面的合理解释。
研究方法：以携带WT、dGRA17、dGRA23或dGRA17rescue遗传背景的刚地弓形虫速殖子（tachyzoites）感染小鼠源骨髓巨噬细胞（Bone Marrow Macrophages，BMDMs），感染时长为4小时。
研究结果：在dGRA17遗传背景的菌株中，GRA23基因的表达水平显著上调，但该效应并未在dGRA23菌株中反向出现。
研究结论：GRA17与GRA23协同作用，为小分子进入刚地弓形虫寄生液泡的通透性过程所必需。
整体实验设计：在感染后4小时，通过Illumina HiSeq2000测序仪开展RNA测序，获取分别感染WT（对照组）、dGRA17、gGRA23及dGRA17rescue（对照组）速殖子的骨髓巨噬细胞中，小鼠与刚地弓形虫的基因表达谱。