13 – cell suicide & assisted suicide & murder Flashcards
Programmed cell death serves to…
shape the body
Programmed cell death – necessary
during brain development
Apoptotic cells – perform
controlled demolition
apoptosis in neurons - how does it work?
developing nervous system
make a lot of motor neuron & send them out, those who has not found their target die of apoptosis
-if dont find good target -> doesnt get signal -> no growth factors -> die
Apoptosis network - to figure out if
cell should die because it is damaged & should be replaced
It is dangerous & should be eliminated
developmental apoptosis alos called
Homeostatic apoptosis
apoptosis prevent: and how
Prevent dying cell from damaging neighbors - neat death
later on phagocytose & removed
apoptosis is a neat death, no explosion, but cell death included cell burst?
necrosis
In necrotic tissue, cell…
Cell burst – cause widespread damage & inflammation
hypothesis of necroptosis:
Can serve as cell-death backup to apoptosis when apoptosis signaling is blocked by endogenous/exogenous factor
Viruses /mutations
Autophagy
A form of programmed cell death
-Cell can digest its own constituents to the point of death
-Cell starves & eats itself
Process of self-destruction (7)
Happens at same time!!!
DNA fragmented
Focal adhesion broken
Actin degraded
Nucleus fragmented
Translation initiators destroyed
Transcription factors destroyed
Goldi & ER fragmented
Found in C.elegans
CED genes – Cell death mutants
-if you have one single gene mutation = no apoptosis
Caspases are…
Effector proteins with 3 dimers
Agents of death in apoptosis
Proteases cut >400 known substrates
C.elegans apoptosis – triggered by & expalin how does it work
release of CED-4 form mitochondria, whenreleased it forms a octamer
- CED-4 octamer binds to CED-3 (caspase)
- CED-3 activates itself by self proteolysis
- cell death
disrupts CED-9/CED-4 complex
EGL-1
what does EGL-1 do?
EGL-1 signal if a cell should die
- it binds to CED-9
- displacing binding by CED-4
- CED-4 now can go form the octamer
what does EGL-1 stand for
& HSN?
EGG LAYING
HSN – hermaphrodite specific neuron
Serotoninergic neuron needed for egg laying
-gain of function mutation in a gene regulatory sequence
2 mobile element in electron trasnport chain
CoQ & Cyt-C (transport electron between outer/inner membrane)
cyt-c also have function of
apoptosis, because mitochondria has function of apoptosis
In mammals – initiator caspases activate
effector caspases by cleavage
in vertebrate apoptosis, important process of Cyt-C
Cyt-C released from intermembrane space into cytoplasm & bind to protein Apaf-1 (similar to CED-4)
cascade of caspases
finally can produce caspase 3 - cleave substrate
Trophic factors & how does it work
Keep Bad in phosphorylated state
prevent Cyt C move out of intermembrane space – reduce apoptosis
1.phosphorylated Bad bind to 14-3-3
2. 14-3-3 can no longer inhibit complex between Back & BCL-2
Apoptosis in mammals
Regulated a multiple level
Balance of pro-apoptotic vs anti-apoptotic signals
-to make sure it is the right thing
Trophic factors inhibit
suicide
but Death signals = murder
Cytotoxic T-cells
Punch holes in membranes
-activate caspase
-cleave negative inhibitor of apoptosis
