Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore.
Dev Cell. 2011 Aug 16;21(2):231-44. doi: 10.1016/j.devcel.2011.06.014. Epub 2011 Jul 21.
Protein toxins such as Ricin and Pseudomonas exotoxin (PE) pose major public health challenges. Both toxins depend on host cell machinery for internalization, retrograde trafficking from endosomes to the ER, and translocation to cytosol. Although both toxins follow a similar intracellular route, it is unknown how much they rely on the same genes. Here we conducted two genome-wide RNAi screens identifying genes required for intoxication and demonstrating that requirements are strikingly different between PE and Ricin, with only 13% overlap. Yet factors required by both toxins are present from the endosomes to the ER, and, at the morphological level, the toxins colocalize in multiple structures. Interestingly, Ricin, but not PE, depends on Golgi complex integrity and colocalizes significantly with a medial Golgi marker. Our data are consistent with two intertwined pathways converging and diverging at multiple points and reveal the complexity of retrograde membrane trafficking in mammalian cells.
蛋白毒素，如蓖麻毒素和绿脓杆菌外毒素（PE），对公共健康构成重大挑战。这两种毒素都依赖于宿主细胞机制进行内化、从内体逆行转运到内质网，以及易位到细胞质。尽管这两种毒素都遵循相似的细胞内途径，但尚不清楚它们在多大程度上依赖于相同的基因。在这里，我们进行了两次全基因组 RNAi 筛选，以确定毒素感染所需的基因，并证明 PE 和蓖麻毒素的需求有很大的不同，仅有 13%的重叠。然而，两种毒素都需要的因素从内体到内质网都存在，而且在形态学水平上，毒素在多个结构中发生共定位。有趣的是，蓖麻毒素而非 PE 依赖于高尔基体复合体的完整性，并且与一个中间高尔基体标志物显著共定位。我们的数据与两条相互交织的途径相一致，这些途径在多个点汇聚和分歧，并揭示了哺乳动物细胞中逆行膜运输的复杂性。
