Cell Death 2 Flashcards
One of the targets of caspases includes mediators and regulators of apoptosis. List 5.
Caspases Bid DFF45/ICAD NDUFS1 IAPs
One of the targets of caspases includes structural proteins. List 4.
Nuclear lamins
Catenins
Vimentin
One of the targets of caspases includes cellular DNA repair proteins. List 3.
DNA-PK
Rad51
ATM
One of the targets of caspases includes cell cycle-related proteins. List 3.
p21
Wee1
Rb
Which enzyme cleaves DNA during apoptosis?
CAD (cleaved from iCAD)
What is MOMP?
Mitochondrial Outer Membrane Permeabilisation
What is MOMP mediated/regulated by?
BCL-2 family members
Extrinsic apoptosis features one of three signalling cascades. What are these?
- Death receptor signalling and activation of the caspase-8 to caspase-3 cascade
- Death receptor signalling and activation of the caspase-8 to tBID to MOMP to caspase-9 to caspase-3 pathway
- Ligand deprivation-induced dependence receptor signalling followed by activation of the caspase-9 to caspase-3 cascade.
What are 4 main targets of caspases?
- Mediators/ regulators of apoptosis
- Structural proteins
- Cellular DNA repair proteins
- Cell cycle-related proteins
What is intrinsic apoptosis mediated by?
MOMP (mitochondrial outer membrane permeabilisation)
What is MOMP?
Mitochondrial Outer Membrane Permeabilisation
What three things is intrinsic apoptosis associated with?
- Generalised and irreversible dissipation of mitochondrial membrane potential
- Release of mitochondrial inner membrane space proteins into the cytosol
- Respiratory chain inhibition
What is intrinsic apoptosis triggered by?
Intracellular stress conditions, including: DNA damage Oxidative stress Ca++ overload ER stress (unfolded proteins)
What are the main biochemical features of extrinsic apoptosis by death receptors?
Death receptor signalling
Caspase-8 (-10) activation
BID cleavage and MOMP (in type II)
Caspase-3 (-6,-7) activation
How can extrinsic apoptosis by death receptors be inhibited?
CmA expression
Genetic inhibition of caspases (8&3)
Z-VAD-fmk administration
What are the main biochemical features of extrinsic apoptosis by dependence receptors?
Dependence receptor signalling PP2A activation DAPK1 activation Caspase-9 activation Caspase-3 (-6,-7) activation
How can extrinsic apoptosis by dependence receptors be inhibited?
Genetic inhibition of caspases (9 & 3)
Genetic inhibition of PP2A
Z-VAD-fmk administration
What are the main biochemical features of caspase-dependent intrinsic apoptosis?
MOMP
Irreversible mitochondrial transmembrane dissipation
How can caspase-dependent intrinsic apoptosis be inhibited?
BCL-2 over expression
Z-VAD-fmk administration
What are the main biochemical features of caspase-independent intrinsic apoptosis?
Release of IMS proteins
Respiratory chain inhibition
How can caspase-independent intrinsic apoptosis be inhibited?
BCL-2 over expression
What TYPE of enzyme are caspases?
Proteolytic enzymes that play a key role in apoptotic cell death
Give two biochemical features of necrosis
Activation of calpains
Activation of cathepsins
Give an example of regulated necrosis
Necroptosis
What can regulated necrosis (eg Necroptosis) be triggered by?
- Alkylating DNA damage
- Excitotoxins
- Ligation of death receptors
What chemical can inhibit most forms of regulated necrosis?
NECROSTATIN-1 (a chemical RIP1 kinase inhibitor)
What is necrostatin-1?
A chemical inhibitor of RIP1 (therefore inhibits regulated necrosis)
What are the 3 main biochemical features of Necroptosis?
- Death receptor signalling
- Caspase inhibition
- RIP1 and/or RIP3 activation
Give two main biochemical features of cornification
- Activation of transglutaminases
2. Caspase-14 activation
What signals for a cell to be phagocytosed?
Flipping of phosphatidylserine from the inner to outer leaflet
How does the PI3K/mTOR pathway affect autophagy?
Inhibits it via p70(56k)
Give 4 biochemical features of autophagy
LC3-I to LC3-II conversion
Dependency on atg gene products
Beclin-1 dissociation from Bcl2/Xl
p62(Lck) degradation
Which diseases has autophagy been primarily associated with?
Neurodegenerative - evidence for the importance of autophagy in the clearance of aggregate-prone proteins, eg those causing neurodegenerative disorders
How does inhibition of mTOR affect autophagy?
Induces it
Inhibition of mTOR induces autophagy. What is the effect of inhibiting mTOR in neurodegenerative diseases like Huntingtons? Why?
It induces autophagy which reversed protein aggregation/accumulation
Why can mTOR realistically not be inhibited therapeutically?
SIDE EFFECTS
As mTOR cannot be inhibited, how else may autophagy be induced in cells?
- L-type Ca++ channel antag
- K+ATP channel opener (MINOXIDIL)
- Gi signalling activator (CLONIDINE)
Name the K+ATP channel opener that can be used to treat diseases like Huntingtons through reversing protein aggregation. How does it do this?
MINOXIDIL
Induces autophagy
Name the Gi signalling activator that induces autophagy to reverse protein aggregation in diseases like Huntingtons
CLONIDINE
When might you want to activate cell death?
In cancer
Which are the functional TRAIL receptors?
TRAIL-R1 and TRAIL-R2
How do the functional TRAIL receptors TRAIL-R1 and TRAIL-R2 induce apoptosis?
Via their DEATH DOMAINS (DDs)
What is TRAIL?
TNF-related apoptosis-inducing ligand
Name some TRAIL-based therapeutics that act as pro-apoptotic agonists at:
1) the TRAIL-R1
2) the TRAIL-R1/R2
1) mapatamuab
2) dulanermin
Name two drugs that act to downregulate the anti-apoptotic Bcl-Xl, Bcl-2 and Mcl-1 proteins (thus releasing inhibition of Bax and Bak)
HAIF-1
ABT-737
Name two drugs that inhibit XIAPs such as survivin
Cisplatin
SM-164
Name a drug that inhibits FLIP, thus releasing inhibition of Caspase 8
Quercetin
Give an example of a drug that induces apoptosis through inhibiting kinases and down-regulating Bcl-Xl and Bcl-2
Flavopiridol
Which family of proteins regulate the outer mitochondrial membrane (OMM) permeability, thus controlling the MOMP?
Bcl-2 family
Anti-apoptotic Bcl-2 over expression may be used to treat which type of diseases?
Neurodegenerative
