Programmed cell death

Programmed cell death is a biological process that happens in all living organisms. It is mediated by an intracellular program with different enzymes involved, depending on the type of programmed cell death. The most important ones are listed below:

• Apoptosis: Biochemical events trigger morphology changes, such as cell shrinkage, nuclear fragmentation, chromatin condensation, or chromosomal DNA fragmentation, which eventually lead to cell death. Apoptosis cannot stop once it begins and, therefore, it is a highly regulated process in the cell. It can be activated via two different pathways (internal and external) but both induce cell death by activating a type of proteases called caspases, which degrades cell proteins until the cell dies.

• Anoikis: Very similar to apoptosis, it occurs in anchorage-dependent cells when they detach from the surrounding extracellular matrix (ECM), which is essential for providing essential signals for growth or survival.

• Autophagy: Catabolic process that results in the degradation of cytoplasmic contents, abnormal protein aggregates, and excess or damaged organelles by autophagosomic-lysosomes. It is generally activated by conditions of nutrient deprivation but has also been associated with physiological processes such as development or differentiation, and and pathological processes like neurodegenerative diseases, stress, infection, and cancer.