Apoptosis and Necrosis (Quiz/Review)

How does the immune system use apoptosis for homestatic control?

After a clonal expansion phase, antigen-reactive lymphocytes must be titrated back until the pool of lymphoid cells reaches the baseline level again.

What is Smac protein?

An IAP antagonist (therefore induces apoptosis = potentil drug involvement).

What's the difference between apoptosis and programmed necrosis?

Apoptosis is self-contained by plasma membrane, usually immediately followed by phagocytosis. Necrosis spills contents into surrounding environment.

Which Bcl-2 family member links intrinsic apoptotic signals (cellular stress), such as DNA damage, infections, to mito-mediated cell death?

BH3-only proteins.

What is Apaf-1 invovled in?

Cascade for caspase activation in apoptosis.

What is the DNA Fragmentation Factor (DFF) that degrades DNA in apoptotic cells?

Caspase-Activated Deoxyribonuclease (CAD; DFF40).

What are the characteristics of apoptosis?

Chromatin condensation, cell shrinkage, preservation of cellular membranes, rapid engulfment by neighboring cells.

What is the structure of caspases?

Dimer with large and small subunits.

What is an IAP?

Inhibitor of Apoptosis (IAP) - inhibit caspases.

What would you see on flow cytometry of DNA fragment staining in apoptotic cells?

Low DNA content - less than in normal cells.

What seem to be the most common disease with apoptotic defects?

Lymphomas.

What cell surface change is a signal to surrounding cells that a cell is going through apoptosis?

Phsophatidylserine (PS). It's normally on the inner leaflet, but fliped out during apoptosis.

How do caspase work?

They recognize different DNA sequences but all cleave at Aspartic Acid (D). They also disable homestatic and repair processes and halt cell cycle progression.

What is the Bcl-2 family of proteins?

"Gate-keepers" in apoptosis. There are anti-apoptotic and pro-apoptotic. Many are capable of (mito?) membrane insertion and forming pores.

What are the two types of necrosis?

Accidental (e.g. after injury) - causing inflammation and damage to surrounding cells by spilling contents; and programmed necrosis.

What are the characteristics of necrosis?

Nuclear swelling, cell swelling, rupture and release of cellular contents, inflammation.