Apoptosis Flashcards
organism commonly used in the study of apoptosis and why
C. elegans; has only 959 cells so each cell could be watched and mapped
apoptosis vs. necrosis
apoptosis is controlled and begins internally; necrosis is initiated by external forces, like damage
Tissue remodeling
-Vertebrate limb bud development - Without apoptosis digits remain joined by soft tissue. (chick and duck hind limbs). - Neural development - Depletion of cells in spinal ganglia occurs during development of the chick embryo.
Survival of Neurons and apoptosis
- in vertebrates the survival of motor neurons depend on the size of the muscle target field they innervate -
- (a) amputation of developing limb bud: removal of limb bub after couple days results in a marked decrease in the number of motor neurons on the affected side - normal numbers of motor neurons were produced on each side, but then many fewer neurons remained on the side with the missing limb
- (b) transplantation of an extra limb bud into an early chick embryo produces the opposite effect
blebbing
- cell membrane undergoes blebbing during apoptosiscell membrane undergoes blebbing during apoptosis
southern blot – apoptosis vs. necrosis
- Apoptosis demonstrates controlled laddering
- Necrosis would have been a smear
senescence
cell has reached the end; deterioration from age
apoptosis process (morphological changes)
Marker of Apoptosis
- phosphatidyl-serine normally found on the inner leaflet but is found on the outer leaflet in apoptosis
- never seen on outside leaflet except in cases of apoptosis
- acts as a signal to surrounding cells that the cell is apoptotic
Pathway: apoptotic stimuli to apoptosis
- Bax and Bak can form a pore in the outer membrane of the mitochondria
- pores form and open à allow the passage of cytochrome C to initiate the apoptotic process
- cyt c attaches to Apaf
- Apaf attaches to wheel of death
- wheel of death = activated Apaf
- formation of an apoptosome
- procaspase 9 sits at center of apoptosome
- procaspase 9 activated when associated with Apaf
- no cleaving of procaspase 9 to caspase 9 (other procaspases do get cleaved)
- caspases 3 6, and 7 are executioner caspases – cut only specific proteins
- targets lamin in nuclear envelope, actin, vimentin (intermediate filament), ICAD (DNAse)
- these caspases are responsible for everything that we saw visually
- Smac/DIABLO is an inhibitor of an inhibitor
Pathway: Apaf + cytochrome c
Intrinsic Apoptosis
Extrinsic Apoptosis
Extrinsic Apoptosis
- caspase 8 is the main player
- found in the immune system
absence of trophic factor
presence of trophic factor pathway
