Mechanisms of apoptosis

Nearly 15 types of programmed cell death (PCD) have been identified to date. Among them, apoptosis is the most common and well-studied type of PCD. In this review, we discuss different apoptotic pathways in which plasma membrane and membrane organelles, such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and nucleus play the pivotal role. Data concerning caspase cascades involved in these mechanisms are described. Various apoptosis induction mechanisms are analyzed and compared. The close relations between them and the possibility of switching from one pathway to another are demonstrated. In most cases, the result of these pathways is mitochondrial membrane permeabilization and/or caspase activation. These two events are closely linked and serve as the central point of integration of the apoptotic cell death pathways.