出版社：American Society for Biochemistry and Molecular Biology
摘要：GM1a [Galß1-3GalNAcß1-4(NeuAc2-3)Galß1-4Glcß1-1Cer]is known to support and protect neuronal functions. However,we report that -linolenic acid-containing GM1a (C18:3-GM1a),which was prepared using the reverse hydrolysis reaction ofsphingolipid ceramide N-deacylase, induced apoptosis in neuronalcells. Intranucleosomal DNA fragmentation, chromatin condensation,and caspase activation, all typical features of apoptosis, wereobserved when mouse neuroblastoma Neuro2a cells were culturedwith C18:3-GM1a but not GM1a containing stearic acid (C18:0)or oleic acid (C18:1). The phenotype of Neuro2a cells inducedby C18:3-GM1a was similar to that evoked by lyso-GM1a. However,lyso-GM1a caused a complete disruption of lipid microdomainsof Neuro2a cells and hemolysis of sheep erythrocytes, whereasC18:3-GM1a did neither. C18:3-GM1a, but not lyso-GM1a, was foundto be abundant in lipid microdomains after the removal of looselybound GM1a by BSA. The activation of stress-activated proteinkinase/c-Jun N-terminal kinase in Neuro2a cells was observedwith lyso-GM1a but not C18:3-GM1a.
These results indicate that the mechanism of apoptosis inducedby C18:3-GM1a is distinct from that caused by lyso-GM1a. Thisstudy also clearly shows that fatty acid composition of gangliosidessignificantly affected their pharmacological activities whenadded to the cell cultures and suggests why naturally occurringgangliosides do not possess polyunsaturated fatty acids as amajor constituent.Abbreviations: Cer, ceramide; CTB, cholera toxin B-subunit; DIM, detergent-insoluble membrane; ERK, extracellular signal-regulated kinase; ESI-LC-MS, electrospray ionization-liquid chromatography-mass spectrometry; GM1a, Galß1-3GalNAcß1-4(NeuAc2-3)Galß1-4Glcß1-1Cer; GSL, glycosphingolipid; MAPK, mitogen-activated protein kinase; NCAM, neural cell adhesion molecule; SAPK/JNK, stress-activated protein kinase/c-Jun N-terminal kinase; SCDase, sphingolipid ceramide N-deacylase
Supplementary key words ganglioside • polyunsaturated fatty acids • neuroblastoma • lipid microdomain
2-3)Galß1-4Glcß1-1Cer] is known to support and protect neuronal functions. However, we report that 
