School of Life Sciences, Peking University, Beijing 100871, China.
Proc Natl Acad Sci U S A. 2010 Oct 19;107(42):18016-21. doi: 10.1073/pnas.1008946107. Epub 2010 Oct 4.
Phagocytosis of apoptotic cells requires recognition of cell corpses followed by internalization and enclosure within plasma membrane-derived phagosomes. Phagosomes undergo maturation to generate phagolysosomes in which cell corpses are degraded; however, regulation of the maturation process is poorly understood. Here, we identified Rab GTPase 14, which regulates apoptotic cell degradation in Caenorhabditis elegans. rab-14 mutants accumulate many persistent cell corpses owing to defective cell corpse clearance. Loss of rab-14 function affects several steps of phagosome maturation including phagosomal acidification and phagolysosome formation. RAB-14 and UNC-108/RAB2 are recruited to phagosomes at a similar stage and function redundantly to regulate phagosome maturation. Three Rabs, RAB-14, UNC-108/RAB2, and RAB-7, act in sequential steps to control phagolysosome formation. RAB-14 and UNC-108 recruit lysosomes, whereas RAB-7 mediates fusion of lysosomes to phagosomes. Our data reveal the sequential action of Rab GTPases in regulating tethering, docking, and fusion of lysosomes to apoptotic cell-containing phagosomes.
细胞凋亡体的吞噬作用需要识别细胞尸体,然后将其内化并包裹在质膜衍生的吞噬体中。吞噬体经历成熟过程以产生吞噬溶酶体,在吞噬溶酶体中细胞尸体被降解;然而,吞噬体成熟过程的调节机制还知之甚少。在这里,我们鉴定了 Rab GTPase 14,它在秀丽隐杆线虫中调节细胞凋亡体的降解。rab-14 突变体由于细胞尸体清除缺陷而积累了许多持久的细胞尸体。rab-14 功能的丧失会影响吞噬体成熟的几个步骤,包括吞噬体酸化和吞噬溶酶体的形成。RAB-14 和 UNC-108/RAB2 在类似的阶段被招募到吞噬体上,并通过冗余作用调节吞噬体成熟。三种 Rab,RAB-14、UNC-108/RAB2 和 RAB-7,依次作用以控制吞噬溶酶体的形成。RAB-14 和 UNC-108 招募溶酶体,而 RAB-7 介导溶酶体与吞噬体的融合。我们的数据揭示了 Rab GTPases 在调节与含细胞凋亡体的吞噬体连接、对接和融合中的顺序作用。