An overview of apoptosis

The concept that cells might possess the capacity to self-destruct by a process of programmed cell death, or apoptosis, is rather recent. Interest in this possibility suddenly galvanized when the first death genes were described in round worms 10 years ago. This led to novel rethinking of many disease processes, such as cancer, which might not purely be due to uncontrolled proliferation, but also to the lack of necessary death of lymphocytes or in autoimmune diseases with the lack of removal of self-reactive lymphocytes. This overview chronicles the events leading up to the paradigm of cell death as an active process. The commonly-used assays for measuring apoptosis are described and compared. Examples of the need for apoptosis are highlighted. This is followed by a discussion of how apoptosis is initiated in a variety of systems and what signal pathways are used, providing suggestions as to how the process of apoptosis might be therapeutically manipulated.