Spindle Pole Body Component Protein 25 (SPC25)

SPBC25 associates with kinetochores from prometaphase through anaphase. Transfection of HeLa cells with siRNA targeted against SPBC25 caused mitotic arrest followed by cell death. In addition, SPBC25 RNAi-treated cells showed a distribution of chromosomes over the mitotic spindle and a significantly longer spindle pole-to-pole distance, showing that SPBC25 is required for normal chromosome congression.SPBC25 interacts with HEC1 throughout the cell cycle and localizes to kinetochores during mitosis. A functional spindle checkpoint is required for the depletion of SPBC25 to cause aberrant mitosis. In addition, immunofluorescence experiments on SPBC25 RNAi-treated cells demonstrated that depletion of SPBC25 causes spindle aberrations and mislocalization of the kinetochore proteins MAD1 and HEC1 during mitosis.