Calcium depletion destabilises kinetochore fibres by the removal of CENP-F from the kinetochore.

The attachment of spindle fibres to the kinetochore is an important process that ensures successful completion of the cell division. The Ca concentration increases during the mitotic phase and contributes microtubule stability. However, its role in the spindle organisation in mitotic cells remains controversial. Here, we investigated the role of Ca on kinetochore fibres in living cells. We found that depletion of Ca during mitosis reduced kinetochore fibre stability. Reduction of kinetochore fibre stability was not due to direct inhibition of microtubule polymerisation by Ca-depletion but due to elimination of one dynamic component of kinetochore, CENP-F from the kinetochore. This compromised the attachment of kinetochore fibres to the kinetochore which possibly causes mitotic defects induced by the depletion of Ca.