Copy correctly
Biologists have revealed the secret of uncontrolled division of cancer cells
A group of biologists from the Gulbenkian Institute in Portugal managed to understand how the mother cell, during division, distributes among daughter cells the correct number of centrioles – organelles involved in the formation of the cell center and the spindle of division, and deviations among which can provoke cancer.
It turned out that there is a special protein that suppresses the copying of extra centrioles. The results are published in the journal Current Biology (Zitouni et al., CDK1 prevents unscheduled PLK4-STIL complex 1 assembly in centriole biogenesis; press release of The cell copying machine: how daughters look like their mothers is published on the Institute's website – VM).
A centriole is a cylindrical cellular structure consisting of microtubules. A cell usually contains two centrioles, but during cell division, each mother centriole produces a daughter centriole. The centrioles in each pair are first attached perpendicular to each other, but then they separate and diverge to the far ends of the cell, forming a spindle of division. The scientists decided to find out what mechanisms are involved in the single copy of the centriole.
The researchers drew attention to the recently discovered key regulator of the formation of centrioles – the protein Plk4. It is activated only before the formation of child centrioles begins, which means that something suppresses it the rest of the time. This ensures the correct number of copies of the tubes.
Biologists found that the CDK1 protein complex (cyclin-dependent kinase), which determines the time of cell division, also turned out to be an inhibitor of Plk4 activity. It prevents the protein from interacting with the STIL substrate. Therefore, Plk4 activates the assembly of new centrioles only in the absence of an active CDK1. In order to double the centrioles before the start of its division, the cell may begin to synthesize substances that suppress cyclin-dependent kinase. Cancer cells can constantly suppress CDK1, provoking excessive copying of centrioles and contributing to their uncontrolled division.
The spindle of division is a structure that ensures the divergence of chromosomes to the poles of the cell during its division. It consists of microtubules attached to chromosomes, and centrosomes – the center of the organization of microtubules of the cell, inside which centrioles are contained. In the cells of malignant tumors, an abnormal number of centrosomes can be detected.
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22.04.2016