Apoptosis (Programmed Cell Death)

• Suicide of the cell
• Cells become more compact
• Blebbing at membranes. Chromatin condensed. DNA fragmented to 180bp

TRIGGERS

• Ligand
• Cytotoxic lymphocyte attacks target
• Withdrawal of necessary growth factor
• Irradiation
• Glucocorticoids

FAS RECEPTOR (Fas or FasR)

• Trigger for apoptosis
• Fas
• Cell-surface receptor related to tumour necrosis factor (TNF) receptor
• Homomeric trimer. Death domain. 
• Fas ligand (FasL)
• Transmembrane protein related to TNF
• Fas + FasL
• Fas trimers ￫ Large aggregates ￫ Activate apoptosis
• TNF + its receptor (TNF-R1) ￫ Apoptosis

DOWNSTREAM FROM THE FAS RECEPTOR

• Classical pathway for apoptosis
• Fas + FasL. TNF + TNF-R1.
• Members of caspase family (cysteine aspartate proteases): Important downstream components
• Pathway involving kinase JNK
• Protein c-Jun ￫ Proteases
• Not blocked by Bcl2