Involvement of proteases in apoptosis.

Genetically programmed (apoptotic) cell death plays a key role in cell and tissue homeostasis and in pathogenesis of various diseases. However, the mechanisms involved in apoptotic cell death are poorly understood. At present, the role of proteases in key events of apoptosis is intensively studied and discussed and the involvement of various proteolytic enzymes in the induction and development of the cell death is well-recognized. Proteases of various classes participating in apoptosis have been identified as well as some substrates of these proteases whose cleavage is critical to cell viability; specific protease inhibitors which prevent the cell death have been synthesized. This review summarizes new data on proteolytic enzymes involved in apoptosis and considers the mechanisms of activation of proteases upon induction of apoptosis and the pathways of their involvement in the cell death. The participation of nuclear proteolytic enzymes in the destabilization of chromatin structure and regulation of DNA fragmentation by endonucleases in apoptotic cells is discussed.