Institute of Cell Biology, University of Bern, 3012, Bern, Switzerland.
Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, MA, 02118, USA.
Sci Rep. 2017 May 19;7(1):2191. doi: 10.1038/s41598-017-02156-7.
The hepatic stage of the malaria parasite Plasmodium is accompanied by an autophagy-mediated host response directly targeting the parasitophorous vacuolar membrane (PVM) harbouring the parasite. Removal of the PVM-associated autophagic proteins such as ubiquitin, p62, and LC3 correlates with parasite survival. Yet, it is unclear how Plasmodium avoids the deleterious effects of selective autophagy. Here we show that parasites trap host autophagic factors in the tubovesicular network (TVN), an expansion of the PVM into the host cytoplasm. In proliferating parasites, PVM-associated LC3 becomes immediately redirected into the TVN, where it accumulates distally from the parasite's replicative centre. Finally, the host factors are shed as vesicles into the host cytoplasm. This strategy may enable the parasite to balance the benefits of the enhanced host catabolic activity with the risk of being eliminated by the cell's cytosolic immune defence.
疟原虫(Plasmodium)的肝脏阶段伴随着一种自噬介导的宿主反应,该反应直接针对含有寄生虫的吞噬小泡膜(PVM)。去除与 PVM 相关的自噬蛋白,如泛素、p62 和 LC3,与寄生虫的存活相关。然而,目前尚不清楚疟原虫如何避免选择性自噬的有害影响。在这里,我们表明寄生虫将宿主自噬因子困在管状囊泡网络(TVN)中,TVN 是 PVM 向宿主细胞质的扩张。在增殖的寄生虫中,PVM 相关的 LC3 立即被重新定向到 TVN 中,在那里它从寄生虫的复制中心远端积累。最后,宿主因子作为囊泡被释放到宿主细胞质中。这种策略可能使寄生虫能够平衡增强的宿主分解代谢活性的益处与被细胞胞质免疫防御消除的风险。