A new component in telomere biology has been discovered, called TZAP. The importance behind TZAP is that it works as a telomere trimmer, making sure that the telomeres do not get any longer. But wait, isn’t having long telomeres a good thing? If you have longer telomeres you live longer right?
As I explained in previous post, telomerase the enzyme in charge of adding those telomere repeats at the end of the chromosomes. However telomerase is active only at certain kind of cells. With each cell division you loss telomere length, that leads (potentially) to aging. So why would you ever need a protein that trims your telomeres?
Among other things, cancer cells have an active telomerase, which means that cancer cells have long telomeres, and they are basically immortal. Therefore the importance behind TZAP is that it will maintain the length of your telomeres at a specific range, that will be the ideal length for the proper function of those. If TZAP was not present, it could lead to a lack of regulation of telomere length that could imply an increase in cancer cells in the body.
The way TZAP works is depicted in this mechanistic picture. Shelterin is another set of telomeric proteins that help the function of telomeres in the protection of the genetic material. After telomeres get elongated by telomerase, there will be less number of shelterin proteins bound to telomeres, which will mean that telomeres are too long. After TZAP ‘senses’ this fact, it will bind to telomeres and start performing is trimming action to maintain an optimal telomere length.