Opening the doors to cytochrome c: changes in mitochondrial shape and apoptosis.

Mitochondria are key organelles in the regulation of apoptosis induced by intrinsic stimuli. This is accomplished by the release in the cytoplasm of cytochrome c and of other cofactors that ensure the activation of effector caspases. Multiple changes in the shape of the organelle occur around the time of the release of these factors, including fragmentation of the mitochondrial network and the activation of the so-called "cristae remodeling" pathway. However, contrasting evidence exist on the functional role of these changes. Here we review the molecular mechanisms that control mitochondrial shape, their changes during apoptosis and the role that these changes might play in the amplification of the apoptotic cascade.