HUANG - LECTURE 4 Flashcards
involvement of apoptosis in development and morphogenesis
apoptosis happens during the metamorphosis from tadpole into frog
also happens between our fingers to get the separation of digits
apoptosis in homeostasis
involved in the immune system and T cell maturation
when T cells proliferate many of them die by programmed cell death
how is the death program controlled
by activators, which come from death signals
by suppressors, which come from survival signals
what are some disease that arise from a decrease of apoptosis
cancer
autoimmune disorders
viral infections
what are some disease that arise from an increase of apoptosis
AIDS
neurodegenerative disorders
bacterial toxins
what are the different types of cell death
during apoptosis and autophagy the contents of the membrane are protected, no membrane rupture
for pyroptosis, oncosis and necrosis the cellular contents are released
necrosis vs apoptosis comparison
what are the things that can lead to necrosis
PARP1 hyperactivation and Fas receptor binding
what is the pathway for programmed cell death in C.elegans
characteristics of caspases
initiator caspases -> effector caspases -> death substrates
which are the two initiator and effector caspases to know and where are they cleaved
initiator caspases: casp-8 and casp-9
effector caspases: casp-3 and casp-7
the cleavage sequence is DEVD, cut after the D (aspartate)
what does fluorescent microscopy reveal about apoptosis?
shows that there is nuclear fragmentation/condensation
also shows that there is cytochrome c release by the mitochondria
what does western blotting tell us about apoptosis
how does flow cytometry work
FACS: fluorescence-activated cell sorting
Sort cells depending on its fluorescent signal
Device that makes a single cell suspension
Laser shines through the region of suspension
Reflection of the laser = cell/granule size
Addition of fluorescent dye
Add different charges and can sort cells based on charges too
how does flow cytometry tell us whether a cell is dying
how does a DEVD cleavage assay work
no cleavage: energy is transferred to the quencher, no signal
cleavage: no quencher, obtain fluorescent signal
what are the two ways in which caspases can be activated
extrinsic:
DISC (death inducing signaling complex)
intrinsic:
MOMP and apoptosome
mitochondria outer membrane permeabilization
how does activation by DISC work
how does TNFR1 lead to necroptosis (necrosis+apoptosis)
apoptosis:
caspase 8 cleaves RIP and apoptosis happens
necrosis:
caspase 8 is blocked by a virus, RIP is not cut
leads to necrosis
how does intrinsic activation by MOMP work
what is the apoptosome and how does it activate
how is there a crosstalk between extrinsic and intrinsic activation of caspases
caspase 8 (extrinsic) cuts Bid into tBid
tBid then stimulates the dimerization of Bax/Bak to create a pore in the mitochondria (intrinsic)
what are the exact steps of the induction of apoptosis by DISC + crosstalk
steps for MOMP
- Apoptotic stimuli
- MOMP formation
- Cyt c released
- Cyt c binds Apaf-1
- Apaf-1 conformation change = unfolding
- Oligomerization of Apaf-1 = formation of apoptosome
- Recruits procaspase-9 (initiator)
- Activation of caspase-9
- Activation of caspase-3/7 (effector)
