Are membranes non-apoptotic compartments for apoptotic caspases

Abstract

Critical mediators of apoptotic cell death are caspases, a highly specialized class of Cys-proteases that cleave substrates after Asp residues. Under normal conditions, caspases are cytosolic proteins. After their activation, they cleave a large number of cytosolic proteins and execute apoptosis (Figure 1, left). However, in addition to their well-studied role in apoptosis, caspases also have many non-apoptotic functions [1, 2]. It is not very well understood how cells escape the potential harmful action of caspases when they perform nonapoptotic functions. In our recent work, we now show that epithelial cells may prevent apoptosis by sequestration of caspases at the plasma membrane, specifically the basal side of the plasma membrane, for non-apoptotic functions [3].