Apoptosis, or programmed cell death, is initiated by a variety of factors. It's a crucial process for development and maintaining tissue health.
Internal and External Triggers of Apoptosis
Several internal and external stimuli can trigger apoptosis:
Internal Triggers:
- DNA damage: Damaged DNA, caused by factors like UV radiation, ionizing radiation, or chemical mutagens, signals the cell to undergo apoptosis to prevent the replication of damaged genetic material. This prevents the propagation of potentially harmful mutations. (Source: Apoptosis can be triggered by a wide variety of cellular stresses, including DNA damage, UV radiation, ionizing radiation, heat shock and oxidative stress, as well as by extracellular stimuli acting through cell-surface receptors.)
- Oxidative stress: An imbalance between the production of reactive oxygen species (ROS) and the ability of the cell to detoxify them can lead to cellular damage and trigger apoptosis. (Source: Glucose-induced reactive oxygen species cause apoptosis of podocytes and podocyte depletion at the onset of diabetic nephropathy. Glucose-induced reactive oxygen species cause apoptosis of podocytes and podocyte depletion in vitro and in vivo.)
- Heat shock: Extreme temperatures can damage cellular components, leading to apoptosis as a protective mechanism. (Source: Apoptosis can be triggered by a wide variety of cellular stresses, including DNA damage, UV radiation, ionizing radiation, heat shock and oxidative stress, as well as by extracellular stimuli acting through cell-surface receptors.)
External Triggers:
- Extracellular stimuli: Signals from outside the cell, often through cell-surface receptors, can initiate apoptosis. For instance, the binding of certain ligands to death receptors can trigger a cascade of events leading to cell death. (Source: Apoptosis can be triggered by a wide variety of cellular stresses, including DNA damage, UV radiation, ionizing radiation, heat shock and oxidative stress, as well as by extracellular stimuli acting through cell-surface receptors.)
- Soluble antigens: In the immune system, high-affinity antigen binding to germinal-center B cells can induce apoptosis, a mechanism for controlling immune responses. (Source: Soluble antigen can cause enhanced apoptosis of germinal-centre B cells.)
- Growth factor withdrawal: The absence of essential growth factors can deprive cells of survival signals, leading to apoptosis.
Examples of Apoptosis in Action:
- Development: Apoptosis plays a crucial role in shaping tissues during embryonic development, removing unwanted cells to create structures like fingers and toes. (Source: Apoptosis is the process of programmed cell death. It is used during early development to eliminate unwanted cells; for example, those between the fingers of a...)
- Immune response: Apoptosis eliminates self-reactive immune cells, preventing autoimmune diseases. (Source: Soluble antigen can cause enhanced apoptosis of germinal-centre B cells.)
- Cancer: Cancer cells can sometimes evade apoptosis, contributing to tumor growth. Conversely, inducing apoptosis in cancer cells is a major goal of cancer therapy. (Source: GTP consumption was found to cause significant apoptosis of PCa cells, which possibly resulted in reduced dissemination of cancer cells, thereby causing...)
