Cell Death Flashcards
What is the purpose of apoptosis?
A defence mechanism to destroy cells that represent a threat to the integrity of the organism
Morphological hallmarks of apoptosis
Blebbing Cell shrinkage Nuclear fragmentation Chromatin condensation Chromosomal DNA fragmentation Global mRNA decay
Biochemical hallmarks of apoptosis
Protein cleavage
DNA fragmentation
Cell surface markers for phagocytosis
Initiator caspases
Caspase 2, 8, 9, 10
Executioner caspases
Caspase 3, 6, 7
What is caspase?
Family of specialised intracellular proteases, used in apoptosis
Negative stimuli of intrinsic pathway of apoptosis
Absence of growth factors/hormones (failure to suppress death programs)
Positive stimuli of intrinsic pathway of apoptosis
Radiation Toxins Hypoxia Hyperthermia Viral infections Free radicals
The intrinsic pathway of apoptosis is triggered by…
Cytochrome C release from mitochondria
What proteins inhibit apoptosis by blocking Cytochrome C release?
Anti-apoptotic Bcl2 family proteins
e.g. Bcl2, BclX(L)
What proteins promote apoptosis by enhancing the Cytochrome C release?
Pro-apoptotic effect Bcl2 family: Bax, Bak
Pro-apoptotic BH3-only protein: Bad, Bim, Bid Puma, Noxa
What are IAPs?
Inhibitors of Apoptosis
Inactivate caspases