Zentrum für Biochemie, Universität zu Köln, Germany.
Cell Microbiol. 2010 Jun;12(6):765-80. doi: 10.1111/j.1462-5822.2010.01432.x. Epub 2010 Jan 11.
Infection of Dictyostelium discoideum with Legionella pneumophila resulted in a large number of differentially regulated genes among them three core autophagy genes, ATG8, ATG9 and ATG16. Macroautophagy contributes to many physiological and pathological processes and might also constitute an important mechanism in cell-autonomous immunity. For further studies we selected the highly conserved ATG9. In colocalization studies with GFP-tagged ATG9 and different organelle marker proteins we neither observed colocalization with mitochondria, the ER nor lysosomes. However, there was partial colocalization with the Golgi apparatus and many ATG9-GFP-containing vesicles localized along microtubules and accumulated around the microtubule organizing centre. ATG9-deficient cells had pleiotropic defects. In addition to growth defects they displayed severe developmental defects, consistent with the known role of autophagy in Dictyostelium development. Unexpectedly, the ATG9 mutant also had a strong phagocytosis defect that was particularly apparent when infecting the cells with L. pneumophila. However, those Legionellae that entered the host could multiply better in mutant than in wild-type cells, because of a less efficient clearance in the early and a more efficient replication in the late phase of infection. We conclude that ATG9 and hence macroautophagy has a protective role during pathogen infection.
秀丽隐杆线虫被嗜肺军团菌感染后,大量基因发生差异表达,其中包括三个核心自噬基因 ATG8、ATG9 和 ATG16。巨自噬参与许多生理和病理过程,也可能构成细胞自主免疫的重要机制。为了进一步研究,我们选择了高度保守的 ATG9。在与 GFP 标记的 ATG9 和不同细胞器标记蛋白的共定位研究中,我们既没有观察到与线粒体、内质网或溶酶体的共定位。然而,与高尔基体有部分共定位,并且许多含有 ATG9-GFP 的囊泡沿着微管定位,并在微管组织中心周围聚集。ATG9 缺陷细胞表现出多种缺陷。除了生长缺陷外,它们还表现出严重的发育缺陷,这与自噬在秀丽隐杆线虫发育中的已知作用一致。出乎意料的是,ATG9 突变体还表现出强烈的吞噬缺陷,当用嗜肺军团菌感染细胞时,这种缺陷尤为明显。然而,那些进入宿主细胞的军团菌在突变体中的繁殖能力比在野生型细胞中更强,因为在感染的早期清除效率较低,而在后期复制效率较高。我们得出结论,ATG9 及其介导的巨自噬在病原体感染过程中具有保护作用。