Live-Cell Imaging in Caenorhabditis elegans Reveals the Distinct Roles of Dynamin Self-Assembly and Guanosine Triphosphate Hydrolysis in the Removal of Apoptotic Cells
Live-Cell Imaging in Caenorhabditis elegans Reveals the Distinct Roles of Dynamin Self-Assembly and Guanosine Triphosphate Hydrolysis in the Removal of Apoptotic Cells
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DOI：
10.1091/mbc.e09-05-0440
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发表时间：
2010-02-15
影响因子：
3.3
通讯作者：
Zhou, Zheng
中科院分区：
文献类型：
--
作者：
He, Bin;Yu, Xiaomeng;Zhou, Zheng
动力蛋白是沿着膜寡聚的大型 GTP 酶。 Dynamin 的膜裂变活性被认为是其在膜运输中的许多生理功能的基础。此前，我们报道了DYN-1（秀丽隐杆线虫动力蛋白）通过促进细胞内囊泡向吞噬杯和吞噬体的募集和融合来驱动凋亡细胞的吞噬和降解，这种活性与动力蛋白众所周知的膜裂变活性不同。在这里，我们检测到活体线虫胚胎中 DYN-1 的寡聚化，并鉴定了 DYN-1 突变，该突变消除了 DYN-1 的寡聚化或 GTPase 活性。具体来说，废除自组装会破坏 DYN-1 与延伸伪足和成熟吞噬体表面的关联，而失活三磷酸鸟苷 (GTP) 结合会阻止 DYN-1 从这些膜上解离。消除 DYN-1 的自组装或 GTP 酶活性会导致常见和差异的吞噬体成熟缺陷。虽然两种类型的突变都会导致 RAB-5 GTP 酶短暂富集到吞噬体表面的延迟，但只有自组装突变而不是 GTP 结合突变会导致将 RAB-7 GTP 酶募集到吞噬体表面的失败。我们提出，在细胞尸体去除过程中，动力蛋白的自组装和 GTP 水解活性建立了对 DYN-1 与其目标膜的瞬时关联的精确动态控制，并且这种控制机制是下游效应器动态招募到目标膜的基础。
Dynamins are large GTPases that oligomerize along membranes. Dynamin's membrane fission activity is believed to underlie many of its physiological functions in membrane trafficking. Previously, we reported that DYN-1 (Caenorhabditis elegans dynamin) drove the engulfment and degradation of apoptotic cells through promoting the recruitment and fusion of intracellular vesicles to phagocytic cups and phagosomes, an activity distinct from dynamin's well-known membrane fission activity. Here, we have detected the oligomerization of DYN-1 in living C. elegans embryos and identified DYN-1 mutations that abolish DYN-1's oligomerization or GTPase activities. Specifically, abolishing self-assembly destroys DYN-1's association with the surfaces of extending pseudopods and maturing phagosomes, whereas inactivating guanosine triphosphate (GTP) binding blocks the dissociation of DYN-1 from these membranes. Abolishing the self-assembly or GTPase activities of DYN-1 leads to common as well as differential phagosomal maturation defects. Whereas both types of mutations cause delays in the transient enrichment of the RAB-5 GTPase to phagosomal surfaces, only the self-assembly mutation but not GTP binding mutation causes failure in recruiting the RAB-7 GTPase to phagosomal surfaces. We propose that during cell corpse removal, dynamin's self-assembly and GTP hydrolysis activities establish a precise dynamic control of DYN-1's transient association to its target membranes and that this control mechanism underlies the dynamic recruitment of downstream effectors to target membranes.