Lecture 15: Cell Death;Apoptosis

Apoptosis

programmed & controlled cell death where cells are deleted without making a fuss about it all

Why is Cell Death Done?

1. When a cell becomes diseased or damaged (virus) 

2. To remove structures/things no longer needed (tails)

3. Maintain tissue size

Why does cancer arise

when there is too little apoptosis

Necrosis

• cell death as a result of acute insult

• UNprogrammed

• inflammatory & MESSY

• cell contents leak all about

Apoptotic Signallign Cascade (what is it)

the signallign cascade that begins apoptosis through caspases

Caspaces

proteases that work to destroy internal parts of the cell during apoptosis

Initiator Capspase

capspases that initiate apoptosis by activating executioner caspases 

Executioner Caspase

capsasapes that are activate day initiator and DISMANTLING the cell 

How are procapsaspes activated and made into capspaces 

• Adaptor proteins cleave the procapspaces and allowing them to become dimerized allowing them to cleave the site in protease domain

• cleavage rearranges them into the large and small subunits

“I CUT YOU, YOU CUT ME” 

Importnat Proteins Cleaved by Executioner Caspasces

• Nuclear Lamin

• Cytoskeleton

• Cell Adhesion Proteins

True or False: Proteases cleave ICAD, letting CAD be free and destroy DNA

true

CAD

nuclease activated by the cleavage of it;s inhibitor protein ICAD

Extrinsic vs Intrinsic Apoptosis

Extrinsic happens due to an outside signal telling the cell to DIE 

Intrinsic happens when the cell is depressed (mitochondrial pathway) 

The Extrinsic Pathway

• damaged cells induce the creation of the Fas receptor

• Induces the formation of the Death Induced Signaling Complex (DISC) 

• DISC activated procaspase 8 to dimerize and cleave each other to become initiator capsules 

Intrinsic Apoptosis Pathway

• cytochrome C launches from the mitochondria

• cytochrome C latches on to the adaptor protein 

• 7 adaptor proteins come together to create the wheel heptameter se llama apoptosome

• apopotosme initiates pro-intirator caspases 

• caspases then the regular pathway. 

Apoptosome

heptameter of adaptor proteins that are connected to cytochrome C 

Bax & Bak

They mediate cytochrome C release by creating a channel for it, Pro-apoptotic 

Survival Factors 

cell signals that inhibit apoptosis but causing the activation of tanscrititon factors and in turn the activation of the BCL2 protein  

BCL2 protein 

an anti-apoptotic protein, (BLOCKED BY JAMES) and does this by messing with Bax/Bak

True or False: The balance between pro & anti- apoptic factors determine whether a cell lives or DIES

true

If apoptotic stimulus is there what happens to BCL2

it gets chopped, for Bax & Bak to get to work