C18:3-GM1a induces apoptosis in Neuro2a cells: enzymatic remodeling of fatty acyl chains of glycosphingolipids

Abstract

GM1a [Gal ␤ 1-3GalNAc ␤ 1-4(NeuAc ␣ 2-3)Gal ␤ 1-4Glc ␤ 1-1Cer] 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 of sphingolipid ceramide N -deacylase, induced apoptosis in neuronal cells. Intranucleosomal DNA fragmentation, chromatin condensation, and caspase activation, all typical features of apoptosis, were observed when mouse neuroblastoma Neuro2a cells were cultured with C18:3-GM1a but not GM1a containing stearic acid (C18:0) or oleic acid (C18:1). The phenotype of Neuro2a cells induced by C18:3-GM1a was similar to that evoked by lyso-GM1a. However, lyso-GM1a caused a complete disruption of lipid microdomains of Neuro2a cells and hemolysis of sheep erythrocytes, whereas C18:3-GM1a did neither. C18:3-GM1a, but not lyso-GM1a, was found to be abundant in lipid microdomains after the removal of loosely bound GM1a by BSA. The activation of stress-activated protein kinase/c-Jun N-terminal kinase in Neuro2a cells was observed with lyso-GM1a but not C18:3-GM1a. These results indicate that the mechanism of apoptosis induced by C18:3-GM1a is distinct from that caused by lyso-GM1a. This study also clearly shows that fatty acid composition of gangliosides significantly affected their pharmacological activities when added to the cell cultures and suggests why naturally occurring gangliosides do not possess polyunsaturated fatty acids as a major constituent. -Nakagawa, T., A. Morotomi, M. Tani

Ceramidase Enhances Phospholipase C-induced Hemolysis by Pseudomonas aeruginosa

“…Although how CDase enhances SMase-or PlcHinduced hemolysis in the presence of HSA is still unclear at present, it was elucidated that the conversion of Cer to Sph followed by withdrawal of Sph from the plasma membrane by HSA accelerated hemolysis. It is worth noting that lysosphingolipids but not parental sphingolipids, can disrupt erythrocyte membranes via a nonspecific detergent-like effect (35)(36)(37). Sph, a kind of lysosphingolipid, may have a similar effect.…”

MALDI mass spectrometry imaging of gangliosides in mouse brain using ionic liquid matrix

“…However, glycolipids show heterogeneity not only in their carbohydrate moiety but also in their lipid moiety [23]. Whereas most studies focus on functional roles of glycolipid carbohydrate moiety, little is known how the composition of ceramide moiety affects ganglioside function.…”

Membrane lipid rafts are required for AMPA receptor tyrosine phosphorylation

“…The gradients were spun at 40,000 rpm for 5 h at 4°C in the SW41 rotor. Six fractions were collected from top to bottom of centrifuge tubes ( Smart et al, 1995 ; Lafont et al, 1998 , 1999 ; Oliferenko et al, 1999 ; Lindwasser and Resh, 2001 ; Inoue et al, 2004 ; Nakagawa et al, 2005 ; Pike et al, 2005 ). An amount of 2 ml of each fraction was diluted by the addition of equal volume (2 ml) PBS and concentrated by ultrafiltration with Centricon30 (Amicon).…”