Apoptosis

Abstract

Apoptosis is a physiologic type of programmed cell death that is essential for normal development and regular life of tissues and organs. It is used by multicellular organisms for elimination of “unwanted” cells, which may include excess and unnecessary cells, defective, senescent and harmful cells. Any apoptosis disorder potentially leads to diseases. By contrast to necrosis, which is a nonphysiologic accidental cell death resulting from irreversible cell injury, apoptosis takes place according a genetic cell-suicide programme and is an active process initiated by extern signals or by intrinsic events, such as DNA-damage or irreparable stress at cellular organelles. Both pathways that initiate and regulate apoptosis, the death receptor pathway and the mitochondrial pathway,lead to the activation of particular proteases called caspases (cysteine aspartic acid-specific proteases). A cascade of caspase-mediated cleavage processes takes place causing dramatic cellular changes, which give rise to the characteristic morphological apoptosis patterns.