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Final Activity Report Summary - AURORA A IN MITOSIS (Role of Aurora A kinase in establishment and maintainance of spindle bipolarity during mitosis)

Centrioles are cylindrical structures, the walls of which are composed of microtubules. Two centrioles arranged orthogonally and surrounded by a dense cloud of proteins form the centrosome. The centrosome is the main centre for nucleation of microtubules. Our work identified a new component, Klp10A, localised along the centriole and enriched on its ends. When levels of Klp10A are greatly reduced at this location, longer, broken and fragments of centrioles are observed in the cells of Drosophila testes at various stages of mitotic and meiotic divisions. Moreover, flies depleted for Klp10A are uncoordinated and sterile. Uncoordination and sterility are generally a consequence of defective ciliated cells of the nervous system and defective germ lines.

Longer and damaged centrioles are also detected in Drosophila cultured cells depleted for klp10A. Depolymerisation of microtubules by Klp10A has been previously shown to be responsible for the shortening of the microtubules in interphase cells and for controlling the length of the mitotic spindle. Our results show that the formation of overly long centrioles is also directly linked to the microtubule depolymerising activity of Klp10A. These elongated centrioles would then fragment when submitted to elevated tension of microtubules motors on centrosomes during mitosis.

Thus, in addition to regulating the length of cytoplasmic microtubules, Klp10A controls also the length of centriole microtubules. This is necessary to avoid the generation of multipolar spindles due to centrosomal fragmentation and to retain the capacity to nucleate asters or to keep centrioles and so generate basal bodies, cilia and flagella.

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United Kingdom
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