SPICE--a previously uncharacterized protein required for centriole duplication and mitotic chromosome congression

Proper assembly and function of a bipolar mitotic spindle is crucial for faithful bidirectional chromosome segregation during cell division. In animal cells, the two poles of the mitotic spindle are organized by centrosomes, microtubule-organizing structures composed of a pair of centrioles surrounded by the so-called pericentriolar material. Proteomic studies have revealed a large number of centrosome proteins, but many remain uncharacterized. Here, we characterize SPICE, a protein that localizes to spindle microtubules in mitosis and to centrioles throughout the cell cycle. RNAi-mediated depletion of SPICE in human cells impairs centriole duplication and causes severe mitotic defects. SPICE depletion compromises spindle architecture, spindle pole integrity and chromosome congression, even in cells in which centriole duplication has occurred. Our data suggest that SPICE is an important dual-function regulator required for centriole duplication and for proper bipolar spindle formation and chromosome congression in mitosis.