The controls operative during the meiotic cell cycle. Our studies of spatial aspects of the cell cycle attempt to identify some of the general principles underlying cell morphogenesis and how they change during the cell cycle. Cancer involves uncontrolled progression through the cell cycle, and genomic instability is thought to promote the development of cancer. Therefore, improved knowledge of cell cycle and checkpoint controls should contribute to our understanding of cancer. The migration of cells which occurs during metastasis requires changes in cell shape, the control of which should be illuminated by studies on cell morphogenesis.
Transcription continues even in cells arrested in mitosis with highly condensed chromatin.
Despite the high cdc18 transcript levels, Cdc18p does not accumulate in mitotic cells because it is targeted for proteolysis by phosphorylation as a consequence of the mitotic CDK Cdc2p protein kinase. Mutation of the putative Cdc2p phosphorylation sites in Cdc18p allows the protein to accumulate during mitosis. When cells exit mitosis, the mitotic CDK activity falls, stabilising Cdc18p which then rapidly accumulates. This combination of mitotic transcription and CDK mediated proteolysis ensures that exit from mitosis simultaneously prepares cells to initiate DNA replication and undergo S-phase. The presence of CDK activity during G2 could also contribute to the mechanisms which ensure that there is only one S-phase each cell cycle.