Inhibitor of apoptosis

Apoptosis inhibitors ( engl. inhibitor of apoptosis protein, IAP) are a family of proteins that were first discovered in baculoviruses and as endogenous inhibitors of apoptosis (programmed cell death) act.

History

IAP - coding sequences were first discovered in 1993 in the genome of baculoviruses. It was found that IAPs are involved in the suppression of cell death by the baculovirus -infected host cells. Since then, many other IAP representatives were found in different species. This IAPs in common is the presence of at least one BIR domain ( baculovirus IAP repeat), which consists of about 70 amino acids and is responsible for the inhibition of apoptosis.

The IAP family

The human IAP family currently comprises eight proteins.

• The three IAPs XIAP, c- IAP -1 and c- IAP -2 directly inhibit caspases -3, -7, and procaspase -9
• Survivin inhibits caspases -3, -7 and -9.
• C- IAP -1 and c- IAP -2 in the signal transduction of membrane-bound receptors, such as TNF receptor 2 ( TNFR2 ) complex, involved.
• ILP2, ML - IAP, NAIP and BRUCE are other IAPs.

Effects

Tumor cells increase their vitality with the help of apoptosis inhibition and are resistant to immunological and cytotoxic therapies. The absence of caspase activity results in an increased resistance against apoptosis induction. Transformed cells overexpressing survivin and ML- IAP only. Survivin is the most common tumor-specific expressed IAP. This makes it the most interesting member of this protein family and an important study object oncology.