Apoptosis – Programmed cell death

Apoptosis is a pathway of cellular suicide. Occurs without an inflammatory response. Responsible for programmed cell death in important physiological and pathological processes.

E.g.;

Programmed death of the cells in embryogenesis

Hormone dependent physiological involution

Cell deletion in proliferating populations

Irreparable DNA damage

Apoptosis can be triggered by internal and external stimuli.

Internal - p53 activation

Internal embryogenic signals

External – Release of granzyme B by cytotoxic T cells.

Specific ligand receptor interaction

The conversion of these signals to death signal is done by the execution of the caspases. BCL-2 class proteins of the mitochondria regulate the process of apoptosis.

After the execution DNA is fragmented into nucleosome size pieces. Cytoskeleton is broken down and finally karyorrhexis occurs.