Cell Death, Apop/Autophagy Flashcards
apop definition
death by programmed cell death-death by suicide
autophagy defintion
catabolic process includeing digression of cells own component through lysosomes
-cell eats itself
Ncrosis definition
Premature death of cells death by external
Intracellualr=Apoptosis
very similar between different species-same things die
Apoptosis uses
tissue sculpting
Eliminate used T and B cells
Tissue hoeostatus
Eliminating damaged cells
Syndactiliy
no apoptosis between digits
-more severe form of webbing-no differentiation between fingers
caspase-9
apoptosis protein
morphological markers of apop
INTACT CELL MEMBRANES!!!!
large clear valcuoules on surface
look like splitting up into small circles (blebs)
loss of cell cell adhesion
PS flipping
marker of apoptosis
phosphotidyl serine (normally on cyto side-moves to other side_
Annexin 5
antibody to phosphotidyl serine
tell degree of apoptosis
TUNEL
label nicks that are in DNA of apoptotic cells
0added by terminal transferase-adds dUTP
TUNEL advantages/disadvantes
Highsenestity, fast, high reproductibility
No idea of number of strands breaks needed for detection-may miss early stages
- nectrotic cells cause fale positive
- detergent for permeablitizng cells-make fragile
Biomolecular diagnosis for apop
membrane intact, DNA ladering, PS flipping, TUNEl
DNA laddering
caspase degrades DNA-in little ladder rungs
-normal cell is just smear or 1 pand
caspase activation
at 33 kda
can rescue cells after capsize is activated
-remove noxious element
capspases must be cleaved to become activef
- two proteolytic cleavages activate initiator
- initator cleaves effector
cell extrinisic apoptotic pathway
proapoptotic ligand binds to death receptor and activates caspases
caspase facts
cleaved to become active
inititator caspse- 2,8,9, 10
effector (exectue) caspases-3, 6, 7
regulated post translationally (reapidly activated)
caspase cascade (with numbers)
pro-apop stimulus
2,8,9, 10
3,6,7
what does effector cleave? initiator?
initator cleaves effector
effector cleaves nuclear lamina, inhibitors of DNAases (DFF450), Actin
DFF45 inhibits
DFF40-normally exist as inert dimer
-DFF40 oligomerizes before cutting
begins cleaving
Intrinsic apop pathway proteins
BCL2 proteins
-pro-apoptotic- BAX and BAK
-Anti-BCl2, BCL-XL, MCL1
Regulators-DA
BCL
responsible for keeping integrity of mito membrane
Insrinsic apop pathway
LACK of survival signals/DNA damage
-activation of sensor proteins (BH3 only)
-these adhere to mito membrane and make leaky
-leakiness activates Bax/Bak channel
-leakage of city c and other proteins
-also bcl2 is antagonized by BH3 protein-plug up channel
-2, 8-10 get cleaved
-cleave 367
Apop
intrinsic app when cell viable
survival signal and growth factor
-produceds bcl2
bcl2 keeps integrity of protein
P53 has many mechanisms of anticancer function
- activate dNA repair proteins mdm2
- arrest growth by holding cell cycle at g1/s regulation pint
- initate apop
p53 in unstressed cells
-p53 is a tf
kept low concentrations by degradation
- mdm2 adds ubi to p53
- also moves p53 from nun to cyto
mdm2
adds ubi to p53
moves p53 from nuc to cyto (but wants to be in nuc because it is a TF
-53 activation
phosphorylation of N terminal domain -done by protein kinases -MAPK -Checkpoint kinases Onco genes stimiulate p53 activation -mediated by ARF
Problem? what does p53/ mdm2 do
p53 gets activated
mdm2 is inhibited
no send p53 to sit and no ubi
bcl2 proteins
has both pro and anti apop members
BCL2-antiapop
Bak/Bax/bad/bid?-pro apop-get signal from p53 or from dna damage
-normally found in cytosol, translocate to mito membrane and simulate formation allowing cyto c to leak out
BCL, BCLxl, MCL-apop
what does cut c interact with
apaf1-apotosome forms
apoptosomes activates caspase 9 (initiator)
Bid and Bad function
promote apoptosis-te up bcl2 and free bax/bak
-may help open pore
Bcl2 function
binds to bax and bak-prevents pore fomration-anti apoptotic
too much expression leads to cancer
bax and bak function
promote pore formation-release to cyto c and APAF1 intimates apop
little sentence thing
bad biddy frees up baxter bak and ties up bcl-2
bcl2 and chacer
translation puts it in heavily promoted region-linked to cancers
what triggers intrinsic pop pathway
triggered by p53 or response to dna damage
conventioanl anti cancer therapies activate
intrinsic apop by means of p53
p53 activates intrinsic pathway by
transcriptional upreg of BaK/baxter (bcl2 family proteins)
Bax causes
release of city c from mito which bind to ADAPF1 to activate capsize 1
Capase 9
activates cases 3,6,7 destroying critical components of cell
which occurs more intrinsic /extrinisc
intrinsic (80%)
death recepttors?
Dr4 and 5
Apol2L/Trail
activate DR4 and DR5
DR4/5
recruit FADD
FADD recruits
initator caspase 8 and/or 10 to DISC
DISC
death inducing signaling complex
-release case 8 and 10 into cytoplasm
0activte 367
Extrinsic apop pathway
Apo2l/trail bind to membrane death receptors DR4/5
FADD recruited and brings procaspases to DISC-where they are cleaved
Activaes 8 and 10, which activates 3,6,7
independent of p53
Convergence of extrinsic and intrinsic pathways is at
caspases 3,6,7
too much apop
vs
too little apop
cancer, auto immune disease
-cell survival proliferation
radion injury/isehmia/reperfusion
-cell death
Autophagy function
recycle old things/things if don’t have enough energy
sekwester cellular organelle into cytoplasmic actuoles that fuse with lysosomes
4 stages of autophagy
induciton, autophagosome, formation, atuophagosome lysosome fucntion, autophagosome breakdown
Induction
mTOR-serine threonine kinase
nutrient rich-mTOR inhibits autophagy
- starvation-mTOR inactivated
- leads to dephospho rylation events resulting in transcriptional activation of autophagy related genes
MTOR pathway
normaoxia-mTOR active
-phosphate on 4EBP
Hypoxia-4EBP1 not phosphorylated
-binds to ELF4E at CAP-decereased translation
Autophagosome formation
mTOR deactivtion-gene product proteins particulpte in this process
formation of membrane around targeted portion of cell that need to be destroyed
Autophagosome/lysosome fusion
lysosome releases contents into autophagosome
autophagosome breakdown
autophagic body is broken down by degradative nature of lysosome
necrosis
typically caused by factors external to cell
-always detrimental/irreversibel
morphological features of necrosis
cell swelling, chrome digestion, disruption of PM
cell blows up-inflammation response
-usually late necrosis
What do autophagy, apop, necrosis look like
auto=blebs
apop-chromasome condesnation
necrosis-just fucked
