Requirement of Cdk2-cyclin E activity for repeated centrosome reproductionin Xenopus egg extracts

The abnormally high number of centrosomes found in many human tumor cells c an lead directly to aneuploidy and genomic instability through the formatio n of multipolar mitotic spindles. To facilitate investigation of the mechan isms that control centrosome reproduction, a frog egg extract arrested in S phase of the cell cycle that supported repeated assembly of daughter centr osomes was developed, Multiple rounds of centrosome reproduction were block ed by selective inactivation of cyclin-dependent kinase 2-cyclin E (Cdk2-E) and were restored by addition of purified Cdk2-E. Confocal immunomicroscop y revealed that cyclin E was Localized at the centrosome. These results dem onstrate that Cdk2-E activity is required for centrosome duplication during S phase and suggest a mechanism that could coordinate centrosome reproduct ion with cycles of DNA synthesis and mitosis.