Apoptosis: Molecular Mechanisms

Apoptosis is an intrinsic cell-suicide programme, which ensures tissue homeostasis and safeguards the organism by eliminating unnecessary and unwanted cells, or cells that may constitute some form of danger to the organism, for example, tumour cells. Both during embryonic development and in the adult life of organisms, there is a need for a perfect balance between cell proliferation, differentiation and death. This balance is achieved, in part, through the precise regulation of apoptosis, which involves complex molecular events that ultimately activate, or prevent the activation of caspases (cysteine-aspartic acid proteases). The activation of caspases is, in most cases, irreversible and represents the commitment to the cell death fate. Key concepts: Apoptosis is a genetically determined process, by which unwanted or unnecessary cells are eliminated from organisms. Apoptosis is important in many biological contexts and deregulation of apoptosis may cause diseases, either in the case of insufficient apoptosis, which may contribute to excessive cell proliferation and cancer, or excessive apoptosis, which may cause degenerative and other disorders. Many molecules and several signalling pathways contribute to the regulation of apoptosis; both intrinsic and extrinsic factors contribute to the regulation of apoptosis in a cell. Keywords: apoptosis; caspases; IAPs; Bcl-2; p53; c-myc