Necroptosis

Necroptosis is a programmed form of necrosis, or inflammatory cell death. Conventionally, necrosis is associated with unprogrammed cell death resulting from cellular damage or infiltration by pathogens, in contrast to orderly, programmed cell death via apoptosis. The discovery of necroptosis showed that cells can execute necrosis in a programmed fashion and that apoptosis is not always the preferred form of cell death. Furthermore, the immunogenic nature of necroptosis favors its participation in certain circumstances, such as aiding in defence against pathogens by the immune system. Necroptosis is well defined as a viral defense mechanism, allowing the cell to undergo 'cellular suicide' in a caspase-independent fashion in the presence of viral caspase inhibitors to restrict virus replication. In addition to being a response to disease, necroptosis has also been characterized as a component of inflammatory diseases such as Crohn's disease, pancreatitis, and myocardial infarction. Necroptosis is a programmed form of necrosis, or inflammatory cell death. Conventionally, necrosis is associated with unprogrammed cell death resulting from cellular damage or infiltration by pathogens, in contrast to orderly, programmed cell death via apoptosis. The discovery of necroptosis showed that cells can execute necrosis in a programmed fashion and that apoptosis is not always the preferred form of cell death. Furthermore, the immunogenic nature of necroptosis favors its participation in certain circumstances, such as aiding in defence against pathogens by the immune system. Necroptosis is well defined as a viral defense mechanism, allowing the cell to undergo 'cellular suicide' in a caspase-independent fashion in the presence of viral caspase inhibitors to restrict virus replication. In addition to being a response to disease, necroptosis has also been characterized as a component of inflammatory diseases such as Crohn's disease, pancreatitis, and myocardial infarction. The signaling pathway responsible for carrying out necroptosis is generally understood. TNFα leads to stimulation of its receptor TNFR1. TNFR1 binding protein TNFR-associated death protein TRADD and TNF receptor-associated factor 2 TRAF2 signals to RIPK1 which recruits RIPK3 forming the necrosome also named ripoptosome. Phosphorylation of MLKL by the ripoptosome drives oligomerization of MLKL, allowing MLKL to insert into and permeabilize plasma membranes and organelles. Integration of MLKL leads to the inflammatory phenotype and release of damage-associated molecular patterns (DAMPs), which elicit immune responses.