Centrosomes enhance the fidelity of cytokinesis in vertebrates and are required for cell cycle progression

When centrosomes are destroyed during prophase by laser microsurgery, verte brate somatic cells form bipolar acentrosomal mitotic spindles (Khodjakov, A., R.W. Cole, B.R. Oakley, and C.L. Rieder. 2000. Curr. Biol. 10:59-67), b ut the fate of these cells is unknown. Here, we show that, although these c ells lack the radial arrays of astral microtubules normally associated with each spindle pole, they undergo a normal anaphase and usually produce two acentrosomal daughter cells. Relative to controls, however, these cells exh ibit a significantly higher (30-50%) failure rate in cytokinesis. This fail ure correlates with the inability of the spindle to properly reposition its elf as the cell changes shape. Also, we destroyed just one centrosome durin g metaphase and followed the fate of the resultant acentrosomal and centros omal daughter cells. Within 72 h, 100% of the centrosome-containing cells h ad either entered DNA synthesis or divided. By contrast, during this period , none of the acentrosomal cells had entered S phase. These data reveal tha t the primary role of the centrosome in somatic cells is not to form the sp indle but instead to ensure cytokinesis and subsequent cell cycle progressi on.