apoptosis Flashcards
apoptosis vs necrosis
Apoptosis is programmed cell death that is organized and uses ATP. Necrosis is triggered by injury or infection and does not use ATP. Necrosis also produces swelling and disruption of cells (inflammatory cell death)
role of apoptosis?
embryonic development homeostasis cell differentiation removing damaged cells immune surveillance growth
how is mitochondria different in apoptosis vs necrosis?
In apoptosis mitochondria releases its contents like cytochrome c that activates programmed cell death.
In necrosis, the mitochondria swells.
what are proapoptotic proteins?
BAK, BAX, BAD, Bik, Bid, Bim,
what are antiapoptotic proteins?
BCL-2 and BCL-X
describe activation of apoptosis from extrinsic pathway
- FAS ligand from killer lymphocyte binds to FAS protein receptor on the target cell
- FADD recruits procaspase 8 and procaspase 10
- aggregation and cleavage of procaspase-8 molecules activates caspase 8
- activated caspase-8 initatiates caspade cascade which results in apoptosis
describe activation of apoptosis from intrinsic pathway
- cytochrome c in intermembrance space of mitochondria is released into the cytoplasm where it binds to APAF-1
- Aggregation of APAF-1 then binds to procaspase-9.
- activated procaspase-9 results in caspase cascade
what triggers mitochonrial-dependent apoptosis?
oxidants
calcium ions
proapoptotic proteins (BAX, BAK, tBid) to the mitochondrial outer membrane
what can block release of cytochrome c from the mitochondrial intermembrane space?
Bcl2
what makes up the apoptosome?
- Apaf-1
- dATP
- cytochrome c
- caspase 9
what does activation of procaspase 9 lead to ?
cleavage of procaspase 3 resulting in apoptosis
what are death substrates?
ICAD
lamin
vimentin
actin
what is necroptosis?
programmed form of necrosis
viral defense mechanism (cellular suicide)
in presence of viral caspase inhibitors to restrict virus replication.
what is necroptosis used for?
defense against pathogens by the immune system
what is a mitogen?
peptide/protein that stimulates cell division (mitosis)
what does the binding of mitogen lead to?
activation of Ras and MAP kinase cascade
what is myc?
family of regulator genes and proto-oncogenes that code for transcription factors.
what does p53 induce?
apoptosis
what does excessive myc lead to?
activation of p19ARF which inactivates Mdm2 which increases p53 which causes apoptosis
what does protein kinase B (PKB) aka AKT do?
It supresses apoptosis (when a survival factor binds to cell receptor). AKT phosphorylates and inactivates the Bcl-2 family member Bad which causes apoptosis. phosphorylated Bad makes it dissociate from Bcl-2 which suppresses apoptosis.
what is ferroptosis?
programmed cell death dependent of iron and accumulates lipid peroxides.
what is pyroptosis?
a cytotoxic process in macrophages after proteolysis of gasdermin D.
what is anastasis?
a reversal of apoptosis even after caspase activation
what is efferocytosis?
apoptotic cells are removed by phagocytic cells
