Caspase 9 is an initiator in the cysteine aspartic acid protease, or caspase, family. Found in all mammals, it is involved in initiating the programmed death of cells. As an initiator caspase, it works by activating other caspases, called effector caspases, creating a cascade. Effector caspases then break apart the proteins in the cell's nucleus, causing cell death.
Cell death is an important part of the mammalian cell life cycle; cells must die so the body can regenerate newer, healthier cells. The body disposes of the cells through multiple system processes. The process by which cells are programmed to die is called apoptosis.
The function of caspase 9, while very important, is rather simple. When apoptotic stimulation occurs near the cells that are designated by the body as needing to be replaced, a special type of protein, called a cytochrome, containing caspase 9 is released from mitochondria within the cell. It is directed to the nucleus of the cell, where it activates other caspases, namely 3, 6, and 7. They begin cleaving key proteins in the nucleus of the cell, shutting it down. These caspases are sometimes referred to as executioner proteins because of their role.
Health problems can develop if caspase 9 does not function properly. The most common side effects of caspase 9 failures are necrosis, the premature death of cells, and inflammation. If this initiator acts too soon, it can cause a wide variety of symptoms including pain, cell erosion, and even death. When these caspases continue to fail to function over extended periods of time, tumors have been known to develop.
Doctors can detect the abnormal function of caspase 9 by looking for its unique antibody. An antibody is the body's response to the intrusion of a foreign object, and its attempt to fight the abnormality or infection. Caspase antibodies are very specific, and they cannot detect problems with other caspases. This means that when a medical professional detects this specific antibody, he or she can usually narrow the cause of the problem.
To treat these abnormalities, a medical professional can inject the patient with synthetic peptides. This treatment is most effective for delaying premature release of caspase 9, but it also can help prevent tumor development associated with delayed or non-release of the caspase.