Death of Cells

Many cells have a normal life span, after which they simply wear out, die, and are discarded. These include skin cells, the cells that line the intestines, and blood cells. When things go wrong, cells in other organs die, but the entire organism does not necessarily die. For example, cell death in the brain or heart is serious because those organs have only a limited ability to regenerate. Alzheimer’s disease and Parkinson’s disease involve a breakdown of the neuronal network and loss of specific neurons. Death shapes individual organisms during development. The best-known example is in insects. Caterpillars undergo metamorphosis to become butterflies. Under certain disease conditions, cells “commit suicide” by turning on pathways that lead to death. Those mechanisms include apoptosis, autophagy, necrosis, and necroptosis. In recent years, there has been considerable research into ways that these pathways might be manipulated therapeutically.