Research from the University of Haifa has identified killer cells.
A process involving the “murder” of new generation living cells was first discovered in recent research conducted at the University of Haifa. The research, which was featured in the esteemed journal Science advancesfound that during the cell differentiation process in fruit flies, phagocytic cells consume and destroy healthy living cells.
“We have found that phagocytes can act as ‘killers’. Phagocytic cells are known to engulf and dissolve dead cells, but we show for the first time that they also kill newly created normal cells. In essence, we have characterized a new mechanism of cell death. The more we know the mechanisms of cell death, the better we understand how to deal with various diseases, especially cancer, ”explained Professor Hilla Toledano, head of the Department of Human Biology at the University of Haifa and author of the study.
The origin of various body tissues, including skin, hair, stomach and testicles, can be traced back to stem cells. By continuously supplying new cells to replace old ones, these powerful stem cells allow for tissue replenishment. Each stem cell in this process divides into two cells, one of which is stored for future use and the other develops to take the place of the lost cell in the tissue.
In the current investigation, Professor Toledano, Professor Estee Kurant and a group of scientists from the University of Haifa have examined the sex cells of fruit flies. Since many molecular processes in fruit flies and humans are similar, they can be used as an effective model in this situation.
Studies on fruit flies are useful for their ability to monitor processes in living tissues and for the simplicity of genetic alteration, which allows for the exact identification of cellular processes. Six Nobel Prizes have been awarded over the years to scientists who have discovered biological mechanisms in fruit flies that are preserved in humans.
As mentioned earlier, the division of a stem cell into two cells, a stem cell and a cell known as the progenitor, initiates the process of sperm differentiation in male fruit flies. This process continues until functional sperm are formed. Researchers already knew that a quarter of these progenitor cells die and do not turn into sperm from previous studies. The aim of the present study was to better understand what happens to these cells.
The body has a well established and crucial mechanism called cell death. Under normal circumstances, cells have the ability to “commit suicide” when a severe mutation has occurred or after they have achieved their goal. The phagocytes come to “eat” the dying cells, effectively removing their contents and dissolving them. It is known that phagocytes sometimes “eat” the cells of the immune system that have finished their job of defending the body from intruders.
In the present study, the researchers found that phagocytes “kill” a quarter of the progenitor cells in the testis, although these cells are not doing anything “wrong” and are simply undergoing differentiation; they are still new cells and are not abnormal in all respects.
In the first stage, the researchers impeded the phagocytes’ eating abilities and found no dead cells in the tissue. In other words, phagocytes are responsible for the death of progenitor cells.
In the second phase, the researchers used real-time imaging to monitor living tissues and found that progenitor cells are swallowed alive by the phagocyte and only then is the process of death initiated. “We have discovered for the first time a process involving the ‘murder’ of completely normal cells. We still don’t know why this happens. Perhaps this process aims to provide nutrients to maintain a functional stem cell population throughout the life of the organism, ”suggested Professor Toledano.
In addition to understanding a new mechanism, this study may contribute to our abilities to develop drugs and means to control cell death and, in particular, of course, to treat cancer. “Tumors are characterized by constant growth and the interruption of the natural cell death process. If we are able to introduce phagocytes into this process that are able to eliminate live cancer cells, we will be able to control the growth of the tumor. The more we learn about cell death mechanisms, the better we can use these processes to get rid of cancer cells, ”concluded Professor Toledano.
Reference: “Phagocytic cyst cells in Drosophila testis eliminate germ cell progenitors by bundling” by Maayan Zohar-Fux, Aya Ben-Hamo-Arad, Tal Arad, Marina Volin, Boris Shklyar, Ketty Hakim-Mishnaevski, Lilach Porat- Kuperstein, Estee News, 17 June 2022, Science advances.
DOI: 10.1126 / sciadv.abm4937