Abstract FR:

As an organelle coupling nuclear and cytoplasmic divisions, the centrosome is essential to mitotic fidelity and its inheritance could be critical to understanding cell transformation. Investigating the behavior of the centrosome in living mitotic cells, we have documented a transient and remarkable post-anaphase repositioning of this organelle which apparently controls the release of central microtubules from the midbody and the completion of cell division. We further observed that the absence of the centrosome leads to cytokinesis defects. Like the yeast SPB, the mother-centriole could possess a specifically associated activity. That activity would trigger the narrowing of the bridge, for example by disrupting the matrix anchoring MTs in the midbody. A second event would trigger abscission when the mother-centriole moves away from the bridge. The main implication of our work is that disassembly of the central spindle and of the cleavage furrow, both necessary for abscission, are distinct events and would be, like the metaphase spindle disassembly, under checkpoint control. Together with recent results in yeasts, our data point to a conserved centrosome-dependent pathway integrating spatial controls into the decision of completing cell division, which would rely on the repositioning of the centrosome organelle.