Cyclin A/Cdk1 promotes chromosome alignment and timely mitotic progression.
Sarah Y Valles1,2, Shrea Bural1,2, Kristina M Godek1,2
1Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH.
Molecular Biology of the Cell
|October 2, 2024
Summary
Cyclin A/Cdk1 kinase is crucial for timely chromosome alignment during prometaphase, ensuring genomic fidelity. Its depletion delays mitosis by impairing kinetochore-microtubule attachments and protein localization.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Mitotic prometaphase requires precise coordination of spindle formation, kinetochore-microtubule (k-MT) attachments, and chromosome alignment for genomic fidelity.
- Cyclin A/Cdk1 kinase is known to correct erroneous k-MT attachments by destabilizing them.
Purpose of the Study:
- To investigate additional roles of Cyclin A/Cdk1 kinase beyond k-MT attachment destabilization during prometaphase.
- To understand the impact of Cyclin A depletion on chromosome alignment and mitotic progression.
Main Methods:
- siRNA-mediated knockdown of Cyclin A in human cells.
- Microscopy to assess mitotic duration, chromosome alignment, and kinetochore protein localization (BUB1, KNL1, MPS1).
Main Results:
- Depletion of Cyclin A significantly prolonged prometaphase, delaying chromosome alignment.
- Unaligned chromosomes exhibited erroneous k-MT attachments (monotelic, syntelic, lateral).
- Localization of kinetochore proteins BUB1, KNL1, and MPS1 was reduced in Cyclin A-depleted cells, with Cyclin A promoting BUB1 localization independently of its role in k-MT destabilization.
Conclusions:
- Cyclin A/Cdk1 kinase plays a critical role in facilitating chromosome alignment during prometaphase.
- This function is partly mediated by promoting the localization of key kinetochore proteins.
- Cyclin A/Cdk1 kinase is essential for timely mitotic progression and genomic stability.
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