The Golgi checkpoint: Golgi unlinking during G2 is necessary for spindle formation and cytokinesis

Entry into mitosis requires not only correct DNA replication but also extensive cell reorganization, including the separation of the Golgi ribbon into isolated stacks. To understand the significance of pre-mitotic Golgi reorganization, we devised a strategy to first block Golgi segregation, with the consequent G2-arrest, and then force entry into mitosis. We found that the cells forced to enter mitosis with an intact Golgi ribbon showed remarkable cell division defects, including spindle multipolarity and binucleation. The spindle defects were caused by reduced levels at the centrosome of the kinase Aurora-A, a pivotal spindle formation regulator controlled by Golgi segregation. Overexpression of Aurora-A rescued spindle formation, indicating a crucial role of the Golgi-dependent recruitment of Aurora-A at the centrosome. Thus, our results reveal that alterations of the pre-mitotic Golgi segregation in G2 have profound consequences on the fidelity of later mitotic processes and represent potential risk factors for cell transformation and cancer development.