What is the primary action of initiator caspases in response to an apoptotic stimulus?

Initiator caspases play a crucial role in the process of apoptosis, which is programmed cell death. Their primary action is to cleave and activate executioner caspases. When an apoptotic stimulus is detected, initiator caspases, such as caspase-8 and caspase-9, get activated, often through specific signaling complexes. Once activated, these initiator caspases go on to cleave executioner caspases, such as caspase-3, caspase-6, and caspase-7. This activation is essential, as executioner caspases then carry out the death program of the cell by dismantling essential cellular components, leading to apoptosis.

This process is a key step in the apoptotic signaling cascade, transforming a cell from survival to programmed death. The specific action of cleaving and activating executioner caspases ensures a rapid and efficient progression of the apoptotic process, facilitating the breakdown of cellular structures and ultimately allowing the cell to be removed by phagocytes without triggering inflammation.