A New Feature of Cell Division: the Interactions among Chromosome, Telomere and Cell Division
The yellow part refers to telomeres, the protective caps on the ends of chromosomes, moving to the outer edge of a cell's nucleus (the blue part)
The constant new replacing old and impaired contributes to our life maintenance and growth. You may feel at sea by reading the first sentence, well, I’m talking about cells and cell division. During the division process, one cell becomes two; two become four, and so on.
When scientists focus on biomedical research, chromosomes will be a key point, which are duplicated during cell division so that each daughter cell receives an exact copy of a person's genome.
Recently scientists from Salk Institute have discovered a new characteristic of human cell division that may help explain how our DNA is organized in the nucleus as cells reproduce. They found that telomeres, the molecular caps that protect the ends of the chromosomes, move to the outer edge of the cell's nucleus after they have been duplicated as shown as above picture.
In addition to exploring the involvement of telomeres in premature aging diseases and interactions between the DNA damage machinery and telomeres, Karlseder studies the role of telomeres during the cell cycle.
They recorded the movement of how DNA combining with proteins to form chromosomes. In the new study, they used advanced microscopy to track telomere movement in real time throughout the cell cycle for 20 hours in living cells by labeling them with molecules that glowed under the microscope.
As a result, they found that the telomeres moved to the outer periphery of the nuclear envelope of each daughter cell nucleus as they assemble after mitosis, the stage of cell division during which the cell's DNA is duplicated to provide each daughter cell with its own copy. In order to figure out the underlying molecular pathways, the researchers determined that interactions between two proteins, RAP1 and Sun1, seem to tether the telomeres to the nuclear envelope. Sun1 alone was also capable of attracting the telomeres to the nuclear envelope, suggesting the protein is essential for the process and that other elements might be able to replace RAP1 during tethering. The tethering could work as an anchor point to reorganize chromatin after each cell division, so that our DNA is correctly situated for gene expression. It could also play a role in the maintenance of telomeres, thereby influencing aging, cancer development and other disorders associated with DNA damage.
In their next study, they plan to study the telomere tethering.
Now though the spatial reorganization of telomeres are not yet clear, the findings may lighten us on how our genes are regulated and how gene expression programs are altered during cell division.