Microtubule independent vesiculation of Golgi membranes and the reassembly of vesicles into Golgi stacks.
Microtubule independent vesiculation of Golgi membranes and the reassembly of vesicles into Golgi stacks.
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DOI：
10.1083/jcb.122.6.1197
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发表时间：
1993-09
影响因子：
7.8
通讯作者：
Malhotra, V
中科院分区：
文献类型：
--
作者：
Veit, B;Yucel, J K;Malhotra, V
我们最近的研究表明，伊马喹酮（ilimaquinone， IQ）可导致高尔基体膜分解成小泡（VGMs为囊化高尔基体膜），并抑制高尔基池之间的囊泡蛋白运输（Takizawa et al., 1993）。虽然其他胞内细胞器、中间丝和肌动蛋白丝不受影响，但我们发现NRK细胞的IQ处理使细胞质微管解聚。我们提供的证据表明，IQ可以分解高尔基膜，而不考虑细胞质微管的状态。从我们的研究结果可以明显看出，高尔基体膜在紫杉醇稳定微管存在的情况下会被IQ治疗分解。此外，在细胞中，微管首先被微管破坏剂解聚，导致高尔基体相互分离并分散在细胞质中，IQ处理导致这些高尔基体进一步分解为vgm。因此，IQ分解高尔基膜独立于其对细胞质微管的影响。从NRK细胞中去除IQ后，微管和高尔基膜都重新组装。然而，高尔基体膜的重组是通过两个连续的步骤进行的：第一步是微管独立的过程，在这个过程中，vgm融合在一起形成高尔基池堆叠。这一步之后是一个依赖微管的过程，通过这个过程高尔基堆被带到细胞内的核周位置。此外，我们发现IQ在16℃时对高尔基膜的结构组织没有影响。然而，IQ产生的VGMs能够在16℃时融合并组装成高尔基池。这与从BFA处理中恢复的细胞形成对比，在16℃下去除BFA后，存留的高尔基酶不能离开内质网，这一过程被认为需要形成囊泡。我们提出，在16℃时，囊泡形成过程可能普遍受到抑制，而囊泡融合过程不受影响。
We have recently shown that ilimaquinone (IQ) causes the breakdown of Golgi membranes into small vesicles (VGMs for vesiculated Golgi membranes) and inhibits vesicular protein transport between successive Golgi cisternae (Takizawa et al., 1993). While other intracellular organelles, intermediate filaments, and actin filaments are not affected, we have found that cytoplasmic microtubules are depolymerized by IQ treatment of NRK cells. We provide evidence that IQ breaks down Golgi membranes regardless of the state of cytoplasmic microtubules. This is evident from our findings that Golgi membranes break down with IQ treatment in the presence of taxol stabilized microtubules. Moreover, in cells where the microtubules are first depolymerized by microtubule disrupting agents which cause the Golgi stacks to separate from one another and scatter throughout the cytoplasm, treatment with IQ causes further breakdown of these Golgi stacks into VGMs. Thus, IQ breaks down Golgi membranes independently of its effect on cytoplasmic microtubules. Upon removal of IQ from NRK cells, both microtubules and Golgi membranes reassemble. The reassembly of Golgi membranes, however, takes place in two sequential steps: the first is a microtubule independent process in which the VGMs fuse together to form stacks of Golgi cisternae. This step is followed by a microtubule-dependent process by which the Golgi stacks are carried to their perinuclear location in the cell. In addition, we have found that IQ has no effect on the structural organization of Golgi membranes at 16 degrees C. However, VGMs generated by IQ are capable of fusing and assembling into stacks of Golgi cisternae at 16 degrees C. This is in contrast to the cells recovering from BFA treatment where, after removal of BFA at 16 degrees C, resident Golgi enzymes fail to exit the ER, a process presumed to require the formation of vesicles. We propose that at 16 degrees C there may be general inhibition in the process of vesicle formation, whereas the process of vesicle fusion is not affected.