Caspase cascade
The caspase cascade plays a vital role in the induction, transduction, amplification and execution of apoptotic signals within the cell (Figure 2.2).
Figure 2.2. The caspase cascade.Click here to view a PDF of this image.
The caspases are a group of intracellular cysteine enzymes that — upon activation through the intrinsic and/or extrinsic pathways — destroy essential cellular proteins, leading to controlled cell death. There are two tiers of caspase activation during apoptosis. Initiator caspases are activated through the apoptosis-signaling pathways and activate the effector caspases which, in an expanding cascade, carry out apoptosis (Table 2.1).3,4 Caspase cascades are initiated through assembly of multiprotein complexes that trigger activation of the initator caspases which are then released and able to activate the downstream effector caspases.
| Caspase subfamily | Members |
|---|---|
| Initiator caspases | 2, 8, 9, 10 |
| Effector caspases | 3, 6, 7 |
The activation and functions of caspases are regulated by various molecules in the cell, including c-FLIP proteins and inhibitor of apoptosis proteins (IAP).5,6