CaspaseFamilie

The Caspase family is a group of cysteine proteases that play a critical role in programmed cell death, also known as apoptosis. These enzymes are named for their distinctive catalytic mechanism, which involves a cysteine residue in their active site and their ability to cleave peptide substrates after an aspartate residue. Caspases exist in cells as inactive precursors called procaspases, which are activated by proteolytic cleavage. Once activated, caspases initiate a cascade of proteolytic events that dismantle the cell in an orderly fashion, preventing the release of inflammatory cellular contents.

There are two main types of caspases: initiator caspases and executioner caspases. Initiator caspases, such as caspase-8 and caspase-9, are activated by upstream death signals and, in turn, activate executioner caspases. Executioner caspases, including caspase-3 and caspase-7, are responsible for cleaving a wide range of cellular substrates, leading to the characteristic morphological and biochemical changes associated with apoptosis, such as DNA fragmentation, chromatin condensation, and the formation of apoptotic bodies.

Caspases are essential for normal development and tissue homeostasis, and their dysregulation is implicated in various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases. In cancer, caspases can be inactivated, contributing to tumor survival and resistance to therapy. Conversely, excessive caspase activation can lead to excessive cell death, contributing to tissue damage in conditions like stroke or heart attack. Inhibitors of caspases are being investigated as potential therapeutic agents for diseases characterized by uncontrolled cell death.