A new chemical genetics toolbox to analyse genes essential for the mitotic entry
Two mitotic cyclins, cyclin A and cyclin B, are believed to promote mitotic events. However, previous studies have implicated both specific requirement and redundancy of these cyclins in human cells in mitosis. Using degron-tagging approaches, the roles of cyclin B were analysed in RPE-1 and in HeLa cells. Striking di_erences were uncovered between the two cell lines. RPE-1 cells require cyclin B for specific substrate phosphorylations only in metaphase, but HeLa cells without cyclin B stall in an intermediate prophase-like stage which was characterized by a specific morphology and a unique pattern of CDK-substrate phosphorylation. In the absence of cyclin B, endogenous levels of cyclin A alone are responsible for establishing this prophase-like stage found in HeLa cells; but overexpressing cyclin A promoted separate mitotic events in a dose-dependent manner. On the other hand, RPE-1 cells rely on a combination of cyclin A-mediated CDK activity, as well as phosphatase inactivation, to promote separate mitotic events. These results implied that HeLa cells depend on the quantity of, rather than the specific, CDKcyclin activity during mitosis, whereas RPE-1 cells require specific CDK phosphorylations conferred by different cyclins. As the expression of mitotic cyclins is altered in many cancer cells, a comprehensive understanding of the regulation of these cyclins in healthy and cancer cells will allow the design of targeted treatments and a better prediction of patient outcome after therapies.
History
File Version
- Published version
Pages
314Department affiliated with
- Sussex Centre for Genome Damage Stability Theses
Qualification level
- doctoral
Qualification name
- phd
Language
- eng
Notes
Dual-degree programme: The Hong Kong University of Science and Technology and University of SussexInstitution
University of SussexFull text available
- No