Flashcards in Apoptosis Deck (14):
Describe cell morphological changes in apoptosis?
Condensation of cytosol (eosinophilic cytoplasm)
Membrane blebbing into fragments
Fragments phagocytosed by surrounding cells
Cell loss not readily apparent
Important differences between apoptosis and necrosis?
Necrosis will extrude its contents, leading to inflamm. Apop will not.
Necrosis has apparent cell loss, apop doesn't necessarily.
Causes of physiologic apoptosis (5)
Embryogenesis, Clonal deletion, hormone dependent processes, T cells/Immune Modulation, Maintenance of rapidly dividing.
Causes of pathologic apoptosis (5)
2dary to obstruction, Hypoxia
What should you know about Caspases
Carry out protein hydrolysis
Zymogens, Activated by initiator or autocatalytic
Cleave nuclear+cytoskeletal scaffold (lamins)
Cause protein crosslinking
Triggers endonuclease activity
How does DNA breakdown in apoptosis happen?
Activation of Ca and Mg dependent endonucleases
First, break into 50-300 kb pieces, then internucleosomal clevage to multiples of 180-200
How do phagocytic cells know a cell is apoptotic and should be eaten?
Expression of phosphatidylserine ont he outside of the phospholipid membrane (flipped) or thrombospondin expression
Explain the Bcl-2 pathway for regulating mitochondrial fxn
Sensors activate pro-apoptotic members of Bcl-2 family
Release of Cytochrome C as a signal and a docking protein for caspases.
name anti-apoptotic proteins
name pro-apoptotic proteins
bim, bid, bad
BAX AND BAK
Explain the Fas ligand model of apoptosis
Cross linking of TNFR1 or FAS (CD95) allows T cell binding to trigger apoptosis.
Activated surface ligand allows death domain integration into receptor.
Subsequent FADD and Procaspase 8 Activation.
So FAS and Bcl-2 lead you up to the execution phase, whats that all about?
Caspases disrupt cytoskeleton+nuclear matrix
Activation of internucleosomal clevage of DNA
How do live cells prevent phagocytosis?
Expression of CD31