Neoplasia and Apoptosis Flashcards
apoptosis
tightly regulated cell death
apoptotic bodies
cells with intact plasma membranes that will be phagocytized by macrophages
Does apoptosis have an inflammation component?
no
Can apoptosis be physiologic?
yes
Can apoptosis by pathologic?
yes
Physiologic Apoptosis
embryogenesis, involution due to hormone withdrawal, and self-reactive lymphocytes
Pathologic Apoptosis
most commonly due to DNA damage, but can also be accumulation of misfolded proteins, viral infections, or atrophy
2 Phases of Apoptosis
- Initiation Phase
- Execution Phase
2 Pathways in the Initiation Phase
- Intrinsic (Mitochondrial) Pathway
- Extrinsic (death receptor) Pathway
Which caspase is involved in the intrinsic pathway?
Caspase-9
Which caspase is involved in the extrinsic pathway?
Caspase-8
Intrinsic (Mitochondrial) Pathway
Bcl protein regulators activated by irreversible cell damage resulting in increased mitochondrial permeability (MOMP) and and release of cytochrome C into cytoplasm which promotes the formation of the apoptosome and caspase 9 activation
apoptosome
caspase-activating complex promoted by the release of cytochrome-C
MOMP
mitochondrial outer membrane permeabilization
Extrinsic (death receptor) pathway
activated by a “death ligand” (FasL) external to the cell [binding to the Fas receptor on cell membrane], then goes through a second messenger cascade via FADD which activates Caspase-8
FADD
Fas-Associated Death Domain
Are Bcl-2 genes pro or anti apoptotic proteins?
BOTH, mwahaha trick question
Main Caspases involved in the execution phase?
Caspase 3, 6, and 7
(MAINLY Caspase-3)
Execution Phase
cleaves DNA into small pieces, degrades structural components, and fragments to nucleus
Result of the Execution Phase of Apoptosis?
Apoptotic bodies
p53
tumor suppressor gene that will prevent propagation of genetically damaged cells when it is activated
When is p53 activated?
in response in cellular stress or damage, most often due to DNA damage, but also shortened telomeres and hypoxia
3 Ways p53 Prevents Neoplasms
- Quiescence
- Senescence
- Apoptosis
quiesence
temporary cell cycle arrest to allow for DNA repair
Senescence
permanent cell cycle arrest (if DNA repair fails) and cell continues to live on