Researchers from the Katholieke Universiteit Leuven have published a new study on how cell division timing works. The work was published in Molecular Cell yesterday.
Describing the process of cell division, senior author Mathieu Bollen says "First, the chromosomes of a cell are duplicated. Two spindles with so-called microtubules then attach to these chromosomes, allowing the two copies of each chromosome to be separated and pulled into opposite directions. This is how the chromosomes are evenly divided between two new cell nuclei. Then the actual division takes place, creating two daughter cells that are genetically identical to the parent cell."
Issues that arise during cell division include improper attachment of microtubules, sometimes a chromosome doesn't end up in a daughter cell, or even sometimes two chromosomes end up in one cell. The researchers wondered, why do these issues occur?
Junbin Qian, the first author of the paper, found that the timer gives cells the time to fix attachment-related problems. "At the start of the cell division process, the biochemical clock starts ticking when a phosphate group is attached to a key protein. About half an hour later, this phosphate group is removed again. All the while, the distribution of the chromosomes is on hold, allowing the cell to add missing links and fix wrong ones."
Bollen believes that the timer has some potential for cancer therapy. "You want to prevent cancer cells from dividing and spreading. Some of the current cancer therapies target the microtubules in the cell. One example is the drug Taxol, which is produced from yew clippings. Unfortunately, such drugs are toxic and have many unwanted side-effects. Cancer cells are also building resistance to these substances. Now that we know how the cell division timer works, we can start looking for drugs that keep the timer switched on: this brings cell division to a standstill, eventually causing the cancer cells to die. Together with existing treatment methods, this could form an effective combination therapy, because you'd be attacking the cancer cells on several fronts."
Image: Two stages of cancer cell division. The image shows the replicated chromosomes in purple. The cell contains two spindles with microtubules, shown in green. In the top image, these microtubules have attached themselves to contact points (in yellow) of the chromosomes and are pulling the copies away from each other in opposite directions. In the bottom image, this process has been completed and the chromosomes are evenly distributed between what will become the nuclei of the new daughter cells. Image courtesy of KU Leuven's Junbin Qian.