QN1/KIAA1009: a new essential protein for chromosome segregation and mitotic spindle assembly

We previously reported the involvement of QN1 ( quail neuroretina 1) protein in cell cycle control during retinal development. We show here that QN1 is an ATPase conserved through evolution, from fugu to humans. We show that chicken/quail QN1 protein is orthologous to the KIAA1009 protein in humans, the function of which was not known. We demonstrate here for the first time that QN1/KIAA1009 protein is located at the spindle poles of the mitotic apparatus and at centrosomes during mitosis. The siRNA-mediated depletion of KIAA1009 led to abnormal mitosis with chromosome segregation defects and abnormal centrosome separation leading to the death of PC12 and MCF7 cells. Thus, QN1/KIAA1009 is a new microtubule-associated ATPase involved in cell division.