Movement of interphase Golgi apparatus in fused mammalian cells and its relationship to cytoskeletal elements and rearrangement of nuclei.

Virus-induced Vero cell fusion was used to analyze the rearrangement of Golgi apparatus during the development of syncytia. Individual Golgi apparatus, associated initially with the separate microtubule-organizing centers in the perinuclear area of fused cells, congregated in the center of the syncytia and formed an extended Golgi complex within 3 to 5 h. The relocation of the Golgi apparatus, but not of nuclei, depended on the presence of an intact microtubule network, since both the microtubule depolymerizing drug nocodazole and the microtubule-stabilizing drug taxol interfered with the formation of an extended Golgi complex. Depolymerization of microfilaments with cytochalasin D and the complete collapse of intermediate filaments induced by microinjected monoclonal antibodies against vimentin had no effect on these processes. Cooling cells to 20 degrees C inhibited both congregation of Golgi apparatus and relocation of nuclei. Visualization of the movement of Golgi apparatus labeled in living cells with fluorescent metabolites of C6-NBD-ceramide showed that relocation of the Golgi apparatus was a process in which congregation and coalescence of the intact organelles was seen, rather than dispersal and reassembly of smaller Golgi elements in the center of the polykaryons. Thus, movement of intact Golgi apparatus in fused interphase cells depends on an undisturbed microtubule network and occurs independently of the relocation of nuclei.