Dynamics of lipid raft components during lymphocyte apoptosis: the paradigmatic role of GD3

Several investigations have been carried out since many years in order to precisely address the function of lipid rafts in cell life and death. On the basis of the biochemical nature of lipid rafts, composed by sphingolipids, including gangliosides, sphingomyelin, cholesterol and signaling proteins, a plethora of possible interactions with various subcellular structures has been suggested. Their structural and functional role at the plasma membrane as well as in cell organelles such as endoplasmic reticulum and Golgi apparatus has been analyzed in detail in several studies. In particular, a specific activity of lipid rafts has been hypothesized to contribute to cell death by apoptosis. Although detected in various cell types, the role of lipid rafts in apoptosis has however been mostly studied in lymphocytes where the physiological apoptotic program occurs after CD95/Fas triggering. In this review, the possible contribution of lipid rafts to the cascade of events leading to T cell apoptosis after CD95/Fas ligation are summarized. Particular attention has been given to the mitochondrial raft-like microdomains, which may represent preferential sites where some key reactions can take place and can be catalyzed, leading to either survival or death of T cells.