CDK-1 Inhibition in G2 Stabilizes Kinetochore-Microtubules in the following Mitosis.
Cell proliferation is driven by cyclical activation of cyclin-dependent kinases (CDKs), which produce distinct biochemical cell cycle phases. Mitosis (M phase) is orchestrated by CDK-1, complexed with mitotic cyclins. During M phase, chromosomes are segregated by a bipolar array of microtubules called the mitotic spindle. The essential bipolarity of the mitotic spindle is established by the kinesin-5 Eg5, but factors influencing the maintenance of spindle bipolarity are not fully understood. Here, we describe an unexpected link between inhibiting CDK-1 before mitosis and bipolar spindle maintenance. Spindles in human RPE-1 cells normally collapse to monopolar structures when Eg5 is inhibited at metaphase. However, we found that inhibition of CDK-1 in the G2 phase of the cell cycle improved the ability of RPE-1 cells to maintain spindle bipolarity without Eg5 activity in the mitosis immediately after release from CDK-1 inhibition. This improved bipolarity maintenance correlated with an increase in the stability of kinetochore-microtubules, the subset of microtubules that link chromosomes to the spindle. The improvement in bipolarity maintenance after CDK-1 inhibition in G2 required both the kinesin-12 Kif15 and increased stability of kinetochore-microtubules. Consistent with increased kinetochore-microtubule stability, we find that inhibition of CDK-1 in G2 impairs mitotic fidelity by increasing the incidence of lagging chromosomes in anaphase. These results suggest that inhibition of CDK-1 in G2 causes unpredicted effects in mitosis, even after CDK-1 inhibition is relieved.
Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America.
A Sophia
AS
Gayek
Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America.
Ryoma
R
Ohi
D000705:Anaphase; D016203:CDC2 Protein Kinase; D002461:Cell Line, Transformed; D002877:Chromosomes, Human / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016195:G2 Phase; D006801:Humans; D016547:Kinesins / Q000235:genetics / Q000378:metabolism; D018386:Kinetochores / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics / Q000378:metabolism*
C470243:KIF11 protein, human; C486567:KIF15 protein, human; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; D018844:Cyclin-Dependent Kinases; D016547:Kinesins