Cell Copying Machine: How Daughters look like their Mothers

centrioles

PLK4 induced aster formation around centrioles. Credits: Zitouni Sihem and Susana Montenegro Gouveia (IGC).

Ever thought why daughters resemble their mothers? The answer to this was uncovered by a research team from Instituto Gulbenkian de Ciencia (IGC; Portugal), led by Monica Bettencourt-Dias who discovered the mechanism by which the mother copies centrioles only once before distributing it to the two daughter cells.

Centrioles are tiny structures present in our cells that control cell division and motility. Their number is well monitored; as any deviation in number of centrioles leads to infertility microcephaly and accelerates cancer.

Major question in focus was how mother cells copied the centrioles only once? For this, the team focused on investigating the key molecular trigger, a protein named PLK4 that initiates centriole formation.

“We found that the trigger only works just before centrioles are made. Something in the cell was inhibiting the trigger at other time points, ensuring the right copy number of centrioles was formed at the right time,” says Zitouni Sihem, co-first author of this study.

The research team in collaboration with scientists from Germany, USA, Japan and France, investigated what was inhibiting this trigger protein at other time points. “We discovered that a key protein complex that sets the cell division clock, CDK1, inhibits PLK4 activity by kidnapping its partner (STIL). In consequence, PLK4 can only start forming centrioles at a particular time of the cell cycle, when CDK1 is not there,” explains Zitouni Sihem. The centriole formation machinery is thus regulated by the cell cycle clock, ensuring daughters look like their mothers.

Mónica Bettencourt-Dias adds: “I am very proud of this paper, we knew the cell cycle clock and centriole formation had to be linked- otherwise how would cells ensure the right copy number is made? This is the first link showing how the cell cycle machinery regulates the trigger of centriole biogenesis, ensuring the right number of centrioles is formed at the right time, which is critical for homeostasis.”

This study is now published in the latest issue of Current Biology.

The source article can be accessed here.

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