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Role for cyclin-dependent kinase 2 in mitosis exit
V D'Angiolella1, V Costanzo, M E Gottesman
1Dipartimento di Medicina Sperimentale G. Salvatore, Medical School, University of Catanzaro, Via T. Campanella 5, Catanzaro, Italy.
Current Biology : CB
|August 23, 2001
Summary
Cyclin-dependent kinase 2 (cdk2)-cyclin E activity maintains mitosis by stabilizing cyclin-dependent kinase 1 (cdk1)-cyclin B. Protein kinase A (PKA) inactivates cdk2, triggering mitosis exit.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Mitosis relies on cyclin-dependent kinase (cdk) 1-cyclin B activity.
- Exit from mitosis involves cyclin B degradation and cdk1 inactivation.
- Cdk2-cyclin E is active during mitosis and its downregulation is linked to inhibitory phosphorylation.
Purpose of the Study:
- To investigate the role of cdk2-cyclin E in maintaining mitosis.
- To elucidate the mechanism regulating cdk2 activity at the end of mitosis.
- To determine the relationship between cdk2 inactivation and mitosis exit.
Main Methods:
- Experiments using Xenopus egg extracts.
- Analysis of protein kinase A (PKA) activity.
- Inhibition and mutation of cdk2-cyclin E complexes.
- Assessment of cyclin B degradation and cdk1 inactivation.
Main Results:
- Cdk2-cyclin E activity maintains cdk1-cyclin B during mitosis.
- Cdk2 is inactivated by PKA prior to cdk1 inactivation at mitosis exit.
- Premature cdk2 inactivation accelerates mitosis exit.
- PKA inhibition or stabilization of cdk2-cyclin E delays mitosis exit.
Conclusions:
- Proteolysis-independent downregulation of cdk2 activity by PKA is essential for mitosis exit.
- Cdk2 inactivation is a prerequisite for activating the proteolysis cascade leading to mitosis exit.
- The findings reveal a novel regulatory mechanism controlling cell cycle progression.
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