The role of microtubule dependent motors in centrosome movements and spindle pole organization during mitosis

In recent years, it has become clear that both pills and minus end directed motors are required for centrosome separation. In this review, we provide a speculative interpretation of results obtained in various systems. Plus end directed motels associated with centrosomes pushing on microtubules originating from the opposite centrosome may act in concert with plus end directed motors cross-linking anti-parallel microtubules to separate centrosomes in prophase. In addition, minus end directed motors present in the cell cortex could produce pulling forces on astral microtubules that contribute to centrosome separation and determine their final position in relation to cortical cues. Finally, we propose that centrosomes are maintained closely associated with the nuclear envelope during their migration through pulling forces applied on astral microtubules by minus end directed motors associated with the nuclear envelope. We also discuss the role of motors in spindle pole assembly and separation in the absence of centrosomes.