Apoptosis, a form of programmed cell death in multicellular organisms, is directly triggered by FasL(igand)/Fas system. FasL, also known as CD95L, plays a pivotal role in regulating normal B- and T-cell function, suppression of autoimmunity, control of infection, and immune surveillance. As a result of its dual role, namely in self-control of T- cell expansion and in killing of virally infected or neoplastically transformed target cells, Fas/FasL system is involved in disease areas such as autoimmune diseases, cancer and immune deficiency, which are all well-known features of neoplastic diseases, in particular of the lympho-hematopoietic system.
FasL binds the Fas receptor (also known as Apo-1 or CD95), a transmembrane protein, which is part of the TNFR superfamily. The interaction between Fas receptor and FasL results in the formation of the death-inducing signaling complex (DISC), which contains FADD, caspase-8 and caspase-10. In many cell types, processed pro-caspase-8 directly activates other members of the caspase family, and triggers the execution of apoptosis.
