四种Toxoplasma gondii核向因子的组合可以保护人类宿主细胞免受干扰素马驱动的死亡
Brittany Henry1, Aubrey J Phillips1, L David Sibley2
1Department of Infectious Diseases, Center for Tropical and Emerging Infectious Diseases, University of Georgia, Athens, Georgia, USA.
mBio
|September 18, 2024
概括
毒素菌使用四种关键蛋白质阻止人体细胞对干 gamma (IFNγ) 的反应,防止寄生虫逃脱和细胞死亡. 这种机制在人类细胞中是独一无二的,与小鼠不同.
科学领域:
- 免疫学 免疫学 免疫学
- 分子生物学分子生物学
- 寄生虫学的寄生虫学
背景情况:
- 干扰素玛 (IFNγ) 对于控制小鼠和人类的*Toxoplasma gondii* (*T. gondii*) 感染至关重要.
- *T. gondii*使用通过MYR转位元复合体传递的分泌的效应蛋白来抵消宿主免疫反应,包括IFNγ信号传递.
- 之前的研究确定了MYR转位元组件对寄生虫对IFNγ的生存至关重要,但没有具体说明参与阻断IFNγ信号的单个效应蛋白.
研究的目的:
- 为了确定特定的T. gondii*效应蛋白,负责阻断人类细胞中的IFNγ信号传递.
- 调查这些效应因子防止寄生虫外流和宿主细胞死亡的机制.
- 了解人类和小鼠细胞之间T. gondii的免疫逃避策略的差异.
主要方法:
- 在IFNγ原始的人类纤维细胞中进行全基因组功能丧失查.
- 对人类细胞系中的寄生虫退出和宿主细胞死亡表型的分析.
- 研究了已识别的效应因子 (GRA24,GRA28) 与宿主信号分子 (p38 MAPK,CBP/p300) 的相互作用.
主要成果:
- 四个T. gondii*效应因子 (TgIST,GRA16,GRA24,GRA28) 对于完全阻断人类细胞中的IFNγ反应至关重要.
- 在IFNγ刺激的人类细胞中,MYR转位子复合体对于防止过早的寄生虫退出和宿主细胞死亡至关重要.
- GRA24和GRA28直接影响IFNγ驱动的转录;GRA24与p38 MAPK相互作用,GRA28抑制CBP/p300基因组酸转移酶的活性.
- 观察到的防止退出和细胞死亡的表型是人类细胞的独特特征,与之前描述的机制不同.
结论:
- *T. gondii*利用一套特定的核部署效应器来颠覆人类细胞中的IFNγ信号,扩展到JAK/STAT1通路之外.
- 这种以效应器为媒介的阻塞阻止了寄生虫的退出和宿主细胞死亡,这是人类细胞环境中独有的机制.
- 这些发现突出了人类和小鼠宿主之间T. gondii的免疫逃避策略的显著差异,强调了寄生虫的适应性.
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