Apoptosis: Novel Insights into the Role of Death Receptors and Caspases in Cell Fate

Caspases, a group of cysteine-aspartic proteases, have a critical function in carrying out apoptosis, a highly regulated process of programmed cell death that is essential for maintaining tissue balance and promoting development. Caspases are produced as inactive zymogens and can be divided into two groups: initiator caspases (caspase-2, -8, -9, and -10) and effector caspases (such as caspase-3, caspase-6, and caspase-7). Initiator caspases are triggered by apoptotic signals, either through death receptors or mitochondrial pathways, leading to their oligomerization and subsequent activation. This activation then triggers effector caspases, which break down cellular components by means of proteolytic cleavage. These series of events result in distinct changes in the structure and chemistry of the cell, such as the breaking down of DNA, the production of small protrusions on the cell membrane, and the creation of apoptotic bodies. In addition to their traditional function in programmed cell death, recent research suggests that caspases can play a role in non-apoptotic processes such as inflammation, cell differentiation, and tissue remodeling. This chapter consolidates the latest information on the processes of caspase activation, their specificity in targeting substrates, the factors that regulate their activity, and their wider significance in both health and illness. Gaining knowledge about the function of caspases in programmed cell death not only reveals essential aspects of cellular biology but also presents new opportunities for developing treatments for conditions marked by either excessive or insufficient apoptosis.