Thyberg J, Moskalewski S
Department of Medical Cell Biology, Karolinska Institutet, Stockholm, Sweden.
J Submicrosc Cytol Pathol. 1992 Oct;24(4):495-508.
Previous studies have shown that the Golgi complex is broken down into dispersed clusters of vesiculotubular elements as mammalian cells enter mitosis and is reformed in each daughter cell in telophase/cytokinesis. In the present investigation, mannosidase II (a membrane-bound enzyme involved in oligosaccharide processing) was used as a marker to explore the fate of the Golgi complex in dividing L929 and CHO cells in some additional detail. Immunofluorescence microscopy demonstrated a juxta- or perinuclear staining for mannosidase II (man II) in interphase and immunoelectron microscopy revealed that it was restricted to the stacked Golgi cisternae at this stage. As the cells entered mitosis, the staining for man II assumed a pattern of dispersed elements in prophase and then turned into a diffuse pattern during metaphase and anaphase. At the electron microscopic level, this corresponded to a successive disorganization of the Golgi complex, first into structurally modified stacks scattered throughout the cytoplasm, and thereafter into small clusters of vesicles and tubules. In parallel, most of the immunoreactivity for man II was shifted into partially fragmented cisternae of endoplasmic reticulum, and only small amounts were found in the clusters just mentioned. During telophase/cytokinesis a circumscribed staining for man II reappeared in each daughter cell. At the electron microscopic level, cisternal stacks positive for man II were found to reform at the same time as immunoreactivity disappeared from the endoplasmic reticulum. Typically, the Golgi region was first located on the proximal side of the nucleus as related to the intercellular bridge, and then moved to the distal side of the nucleus before the cells were about to separate. Treatment of synchronized mitotic cells with brefeldin A, a fungal metabolite that inhibits endoplasmic reticulum to Golgi transport, prevented reformation of the Golgi complex in telophase/cytokinesis. Nevertheless, the separation of the daughter cells was completed at a similar rate as in the controls. On the basis of these findings, an extended model of the disorganization and reorganization of the Golgi complex in association with mitosis is presented. According to this model the disorganization of the Golgi complex at the onset of mitosis is a two-step process: the Golgi stacks are first separated from each other and spread out in the cytoplasm; thereafter the Golgi stacks disintegrate, at least in part by return of Golgi components to the endoplasmic reticulum. In interphase cells, similar changes in the organization of the Golgi complex are produced by microtubule-disruptive drugs (dispersion of the stacks) and brefeldin A (redistribution of Golgi proteins into the endoplasmic reticulum), respectively.
以往的研究表明，随着哺乳动物细胞进入有丝分裂，高尔基体复合物会分解成泡管状元件的分散簇，并在末期/胞质分裂时在每个子细胞中重新形成。在本研究中，甘露糖苷酶II（一种参与寡糖加工的膜结合酶）被用作标记物，以更详细地探究高尔基体复合物在分裂的L929细胞和CHO细胞中的命运。免疫荧光显微镜显示，在间期甘露糖苷酶II（甘露II）呈核周或核旁染色，免疫电子显微镜显示此时它局限于堆叠的高尔基体潴泡。当细胞进入有丝分裂时，甘露II的染色在前期呈现分散元件的模式，然后在中期和后期变为弥漫模式。在电子显微镜水平上，这对应于高尔基体复合物的连续解体，首先解体为分散在整个细胞质中的结构改变的堆叠，然后解体为小的囊泡和小管簇。同时，甘露II的大部分免疫反应性转移到内质网的部分片段化潴泡中，仅在上述簇中发现少量。在末期/胞质分裂期间，每个子细胞中重新出现了甘露II的局限性染色。在电子显微镜水平上，发现对甘露II呈阳性的潴泡堆叠在免疫反应性从内质网消失的同时重新形成。通常，高尔基体区域首先位于与细胞间桥相关的细胞核近端一侧，然后在细胞即将分离之前移至细胞核远端一侧。用布雷菲德菌素A（一种抑制内质网到高尔基体转运的真菌代谢产物）处理同步化的有丝分裂细胞，可阻止高尔基体复合物在末期/胞质分裂时重新形成。然而，子细胞的分离以与对照相似的速率完成。基于这些发现，提出了一个与有丝分裂相关的高尔基体复合物解体和重组的扩展模型。根据这个模型，有丝分裂开始时高尔基体复合物的解体是一个两步过程：高尔基体堆叠首先彼此分离并在细胞质中散开；此后，高尔基体堆叠解体，至少部分是由于高尔基体成分返回内质网。在间期细胞中，高尔基体复合物组织的类似变化分别由微管破坏药物（堆叠的分散）和布雷菲德菌素A（高尔基体蛋白重新分布到内质网中）产生。
