Sphingolipid research has surged in the past two decades and has produced a wide variety of evidence supporting the role of this class of molecules in mediating cellular growth, differentiation, senescence, and apoptosis. Ceramides are a subgroup of sphingolipids (SLs) that are directly involved in the process of initiation of apoptosis. We, and others, have recently shown that ceramides are capable of the formation of protein-permeable channels in mitochondrial outer membranes under physiological conditions. These pores are indeed good candidates for the pathway of release of pro-apoptotic proteins from the mitochondrial intermembrane space (IMS) into the cytosol to initiate intrinsic apoptosis. Here, we review recent findings on the regulation of ceramide channel formation and disassembly, highlighting possible implications on the initiation of the intrinsic apoptotic pathway.
Keywords: Apoptosis; Assembly and disassembly; Bcl-2 family proteins; Bcl-2, B cell CLL/lymphoma-2; Cer, ceramide; CerS, ceramide synthase; Ceramide channels; Chain length; DES, dihydroceramide desaturase; DHCer, dihydroceramide; ER, endoplasmic reticulum; IMS, intermembrane space; KSR, 3-ketosphinganine reductase; MOMP, mitochondrial outer membrane permeability; Mitochondria; SLs, sphingolipids; SM, sphingomyelin; SPT, serine palmitoyl transferase; So, sphingosine; Sphingolipids; de novo synthesis.