Cellular Apoptosis Pathway
Apoptosis is critical for controlling proliferation and survival of cells, and dysregulation of apoptosis can lead to diseases like cancer. Growth factor receptors signal through PI3K and PKC to inhibit the mitochondrial apoptosis pathway, but withdrawal of these factors leads to release of cytochrome C from mitochondria and the activation of caspase-9. Caspase-9 then induces the intrinsic caspase cascade for apoptosis. Binding of death receptors like FAS and TNFR1 initiates signaling of death domain adaptor proteins FADD and TRADD to activate caspase-8. This leads to stimulation of the extrinsic caspase cascade, resulting in activation of executioner caspases (3, 6, 7) and eventually the fragmentation of DNA.
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