Centromere Clustering and Spindle Organization in Dictyostelium Amoebae

The phenomenon of centromere clustering and its impact are still largely unclear in the eukaryotic supergroup of Amoebozoa. In this review, we highlight the molecular basis for centromere clustering, its relationship to the centrosome, and its role in mitotic spindle organization in Dictyostelium amoebae. Here, the centrosome is anchored to the cytosolic side of the nucleus during interphase and is connected via the nuclear envelope to the nuclear lamina and a cluster of the centromeres of all six chromosomes. Upon transition from the G2 phase to mitosis, the centrosome penetrates a fenestra in the persisting nuclear envelope and duplicates. During this process, microtubule connections are established between the mitotic centrosomes and the kinetochores. We review all known molecular players in this process and pose a hypothesis on how the centromere protein Cenp68, which is related to monopolin from fission yeast, could facilitate and accelerate the process of mitotic spindle formation.