14. Programmed cell death in eukaryotes Flashcards
Reasons for PCD
Regulation of cell numbers Developmental importance Body function, e.g. sculpting structures Elimination of diseased or dangerous cells (e.g. cancer)
Why is necrosis not a type of PCD?
No genetic programme
Hallmarks of apoptosis
external or internal signal
involvement of signal transduction
defined catabolism of cellular components
chromatin condensation
fragmentation of the nucleus
almost no morphological modifications of organelles
cell shrinkage
intactness of mitochondria and plasma membrane
plasma membrane blebbing
cellular disintegration („apoptotic bodies“)
degradation in phagocytic lysosomes of adjacent cells
Main difference between intrinsic and extrinsic pathway
Intrinsic - apoptosome
Extrinsic - DISC
Procaspase and caspase in intrinsic and extrinsic
intrinsic - 9
extrinsic - 8
What is the protein attached to the Fas death receptor?
FADD
What is the apoptosome composed of?
many APAF1 – Apoptotic protease activating factor 1
APAF1 composition
CARD – caspase recruitment domain
WD40 repeat – repeat sequence of ~40 aa; repeats form circular β-propeller structures Winged helix domain – interacts with (d)ATP / (d)ADP
What is the apoptosome?
A signalling platform that activates the extrinsic pathway
Which two mechanisms does mitochondrial membrane permeabilisation involve?
- Mitochondrial outer membrane permeabilisation (MOMP) by BAX/BAK at the outer membrane
- Mitochondrial permeability transition (MPT) by Ca2+ and ROS at the inner membrane (IM) opens the Permeability Transition Pore Complex (PTPC)
Examples of anti-apoptotic proteins
Bcl-2 family - act on intrinsic pathway
IAP family - act on both pathways
What do IAP family act as?
E3 ligase
Apoptotic features which plants and mammals share
Cell shrinkage
DNA laddering
Chromatin condensation
Differences in plants
No caspases
No Bcl2 family
Roles of PCD in plants?
Formation of trachery elements Lignification (xylogenesis) Organ development
Senescence
abiotic and biotic stress
