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IBMC researchers identify a new mechanism to control cell division


Mitosis is the process by which a cell divides to give rise to two identical daughter cells with the same number of chromosomes and DNA as the mother cell. It is one of the most elegant and finely regulated biological processes that exists. Each stage of mitosis is tightly controlled in time, and a number ofcheckpoints have been identified that prevent an event from occurring before the previous event has finished. In the latest issue of the journal Sciencea team led by Helder Maiato, from the Associate Laboratory Instituto de Biologia Molecular e Celular (IBMC) of the University of Porto, describes a spatial checkpoint that ensures that the nuclei of the two daughter cells are formed only when the chromosomes are properly separated, so that no chromosome is left behind.

During mitosis, the chromosomes of the cell line up in pairs in the equatorial plane of the cell. Each pair is then separated, and the chromosomes migrate along protein cables toward the opposite poles of the cell. Hélder Maiato and his team discovered that a gradient of the Aurora protein acts as a kind of ruler in the cell, monitoring the positions of chromosomes relative to the equatorial plane and preventing nuclei from forming before the chromosomes are at a minimum safe distance apart. This new surveillance mechanism allows for the reintegration of lagging chromosomes into the new nuclei before the membranes surrounding them are fully formed.

When the Aurora protein gradient is disturbed, either globally or locally, the switch that links chromosome separation and new nuclei formation stops working, leading to abnormalities such as nuclei with too many copies of chromosomes or micro-nuclei within the cell. These situations can lead to disease situations, such as cancer, so understanding these mechanisms is a crucial step towards controlling them, with strong implications for human health.