Apoptosis PDF

Need Of Apoptosis • Apoptosis is needed for proper development Examples: The resorption of the tadpole tail The formation of the fingers and toes of the fetus The formation of the proper connections between neurons in the brain • Apoptosis is needed to destroy cells Examples: Cells infected with vir...

Need Of Apoptosis • Apoptosis is needed for proper development Examples: The resorption of the tadpole tail The formation of the fingers and toes of the fetus The formation of the proper connections between neurons in the brain • Apoptosis is needed to destroy cells Examples: Cells infected with viruses Cells with DNA damage Cancer cells Reasons of apoptosis • Withdrawal of positive signals a examples : – growth factors for neurons – Interleukin-2 (IL-2) • Receipt of negative signals examples : – increased levels of oxidants within the cell – damage to DNA by oxidants – death activators : • Tumor necrosis factor alpha (TNF-α) • Lymphotoxin (TNF-β) • Fas ligand (FasL) a Inducers of Apoptosis e • TNF family • Growth factor withdrawl I • Calcium • Oncogenes • Nutrient deprivation • Toxins • UV radiation • Gamma radiation I’m Types Two types: - those involved in apoptosis: Initiators – activate downstream effector caspases to initate Is activation cascades: Caspases2 Caspases9 Caspases8 Caspases10 Effectors - cleave target proteins resulting in morphological and biochemical markers of apoptosis: Caspases3 Caspases6 Caspases7 Caspases14