Apoptosis, or programmed cell death, is an essential physiological process that plays a critical role in development and tissue homeostasis. The progress of apoptosis is regulated in an orderly way by series of signal cascades under certain circumstances. The caspase-cascade system plays vital roles in the induction, transduction and amplification of intracellular apoptotic signals. Caspases, closely associated with apoptosis, are aspartate-specific cysteine proteases and members of the interleukin-1β-converting enzyme family. The activation and function of caspases, involved in the delicate caspase-cascade system, are regulated by various kinds of molecules, such as the inhibitor of apoptosis protein, Bcl-2 family proteins, calpain, and Ca2+The caspases are not the only executors of apoptotic change. Various pathways that result in apoptosis without the action of the caspase fraternity have been described. One involves a protein termed AIF (apoptotic initiating factor) that is released from the mitochondria, enters the nucleus and triggers cell suicide. Note that not all caspases are death-mediating enzymes; some have a role in the processing and activating of cytokines (e.g. caspase 8 is active in processing the inflammatory cytokines IL-1 and IL-18). In apoptosis the cardinal morphological features are cell shrinkage, accompanied by trisient but violent bubbling and blebbing from the surface, and culminating in separation of cell in cluster of membrane bounded bodies. Change in several cell surface molecule also ensure that, in tissues, apoptotic cell are immediately recognised and phagocytosed by their neighbours. The result is that many cells can be deleted from tissues in relatively short time. Apoptosis is clinically implicated in various body systems like cardiovascular system, central nervous system, gastrointestinal system, reproductive system, immune system and various pathological conditions like cardiovascular diseases, neurodegenerative disorder, cancer, sepsis, renal diseases Deficient apoptosis is associated with cancer, auto-immunity and viral infections. Excessive apoptosis is associated with ischaemic heart disease, stroke, neurodegenerative disease, sepsis and multiple organ dysfunction syndrome.
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