Apoptosis << ap uh TOH sihs >>, also called programmed cell death, is a process that results in the controlled self-destruction of a cell. This genetically regulated process is an important part of the normal growth and development of organisms. Apoptosis provides for the orderly elimination of unnecessary and worn-out cells and also plays a role in certain diseases. For example, apoptosis can limit the uncontrolled division of cells that leads to cancer.
Cells contain genes that promote apoptosis, called proapoptotic genes. Genes that prevent apoptosis from occurring, called antiapoptotic genes, also exist in most cells. The balance between apoptosis promotion and apoptosis prevention determines if a cell triggers its own death. Apoptosis can also be activated by external factors, such as X rays and certain drugs and hormones.
Several physical changes occur when a cell undergoes apoptosis. The cell shrinks, detaches from other cells, and breaks into particles called apoptotic bodies. Apoptotic bodies are then engulfed and digested by neighboring cells. This process prevents leakage of cell contents and inflammation, a reaction to cell damage.
Many diseases and conditions can cause apoptosis, including viral infections, toxins (poisons), and oxygen deprivation. Scientists are working to develop drugs that prevent apoptosis when the process contributes to disease. They are also seeking to produce other drugs that promote apoptosis when the process is desired for killing cancer cells.
