Figure 7

Aurora-A modulates the balance of forces required for spindle pole integrity: a model. Left upper panel: in a normal mitosis balanced MT forces determine the formation of a symmetrical bipolar spindle. Arrows represent opposite-directed MT forces. Right upper panel: in Aurora-A-defective mitoses, the spindle displays fragmented poles. Lower panel: spindle pole disruption is prevented by either inactivating a MT stabiliser (ch-TOG), or weakening KT-generated (Nuf2 silencing), or inhibiting motor-associated (Eg5 inhibition) centrosome-directed MT forces in the absence of Aurora-A activity. The model suggests therefore that spindle poles fragment consequently to the imbalance in MT-generated forces in Aurora-A-defective mitoses.