A unified view of spatio-temporal control of mitotic entry: Polo kinase as the key
The Polo kinase is an essential regulator of cell division. Its ability to regulate multiple events at distinct subcellular locations and times during mitosis is remarkable.
The functional relationship between activating phosphorylation of the KD and SUMOylation of the PBD in triggering the nuclear import of Polo remains to be explored.
How SUMO and ubiquitin differentially affect the ability of the PBD to interact with different substrates, regulators or the KD of Plk1 has not been investigated.
The importance of bringing Polo activity in the nucleus before NEB for these other functions, and to what extent each event is required for the normal completion of mitosis, has not been dissected in detail
The precise mechanisms linking Polo and the Gwl–PP2A module remain to be elucidated.
it is now clear that Polo relies on built-in mechanisms by which its activation triggers changes in subcellular localization that are required for Polo to coordinate multiple events in space and time as the cell enters mitosis.
Knowledge of the precise mechanism by which Bora (and its phosphorylation by Cyclin A–Cdk1) helps activate Plk1 (Polo) is still lacking and will likely require structural biology approaches.
Further work will be required to fully understand how phosphatasaes contribute to the spatio-temporal regulation of Polo kinase.
Although still incomplete, the new knowledge of the complex mechanisms enforcing spatio-temporal control of Polo kinase during mitotic entry constitutes a major leap forward in our understanding of cell division at the molecular level. Much work remains to be done to comprehend the regulation and precise functions of Polo kinase in late phases of cell division, including cytokinesis.
Common Design 