Process of dispersion and fragmentation of Golgi complex by microtubule bundles formed in taxol treated HeLa cells.

By means of a monoclonal antibody (mAbG3A5) against Golgi membrane glycoprotein, we have visualized the relative position of cytoplasmic polymerized microtubule bundles to Golgi stack cisternae in taxol treated HeLa cells, and found extensive fragmentation of the Golgi stack cisternae brought about by microtubule bundles. Within a 1 h period of taxol treatment, polymerization of cytoplasmic microtubules increased rapidly to form microtubule bundles, while the Golgi complex dispersed slightly along with the polymerized microtubule bundles. After 2 to 3 h taxol treatment the dispersal of the Golgi complex from the microtubule-organizing center (MTOC) to cytoplasmic periphery rapidly progressed in the direction which the microtubules ran. At early dispersal, the microtubule bundles were oriented apart from the stretched end of the Golgi stack cisternae and exhibited little direct contact with the Golgi stack cisternae membrane. The Golgi stack cisternae then began to wind around the microtubule bundles, followed by the beginning of fragmentation of the Golgi stack cisternae. At this step, some of the microtubules seemed to attach to a part of the Golgi stack cisternae. After prolonged exposure of cells to taxol (25 h) the microtubule bundles were highly developed throughout the cells and most of the Golgi fragments were trapped at their termini. In these cells, extensive fragmentation of Golgi stack cisternae occurred, resulting in small Golgi vesicles bound to the microtubule bundle.