Acyl chain length affects ceramide action on sterol/sphingomyelin-rich domains.
The effects of ceramides with varying saturated N-linked acyl chains (C2-C14) on cholesterol displacement from sphingomyelin-rich domains and on the stability of ordered domains were studied. The bilayers examined were made from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), D-erythro-N-palmitoyl-sphingomyelin (PSM), D-erythro-N-acyl-sphingosine, and cholesterol (60:15:15:10 mol%, respectively). Cholestatrienol (CTL) or D-erythro-N-trans-parinoyl-sphingomyelin (tParSM) were used as reporter molecules (at 1 mol%) for the ordered domains, and 1-palmitoyl-2-stearoyl-(7-doxyl)-sn-glycero-3-phosphocholine (7SLPC) as a fluorescence quencher (30 mol%, replacing POPC) in the liquid-disordered phase. The results indicate that the ceramide had to have an N-linked acyl chain with at least 8 methylene units in order for it to displace cholesterol from the sphingomyelin-rich domains at the concentration used. The melting of the sphingomyelin-rich domain shifted to higher temperatures (compared to the ceramide-free control) with C2, C12 and longer chain ceramides, whereas C4-C10 ceramides led to domain melting at lower temperatures than control. This study shows that short-chain ceramides do not have the same effects on sterol- and sphingomyelin-rich domains as naturally occurring longer-chain ceramides have.
Nybond
Susanna
S
Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistökatu 6A, FI 20520 Turku, Finland.
Björkqvist
Y Jenny E
YJ
Ramstedt
Bodil
B
Slotte
J Peter
JP
D002518:Ceramides / Q000737:chemistry*; D005456:Fluorescent Dyes; D008051:Lipid Bilayers / Q000737:chemistry*; D008560:Membrane Fluidity; D013109:Sphingomyelins / Q000737:chemistry*; D013261:Sterols / Q000737:chemistry*; D013696:Temperature
D002518:Ceramides; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D013109:Sphingomyelins; D013261:Sterols