Ceramide-1-Phosphate, in Contrast to Ceramide, Is Not Segregated into Lateral Lipid Domains in Phosphatidylcholine Bilayers

Abstract

Sphingolipids are key lipid regulators of cell viability: ceramide is one of the key molecules in inducing programmed cell death (apoptosis), whereas other sphingolipids, such as ceramide 1-phosphate, are mitogenic. The thermotropic and structural behavior of binary systems of N-hexadecanoyl-D-erythro-ceramide (C(16)-ceramide) or N-hexadecanoyl-D-erythro-ceramide-1-phosphate (C(16)-ceramide-1-phosphate; C(16)-C1P) with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was studied with DSC and deuterium nuclear magnetic resonance ((2)H-NMR). Partial-phase diagrams (up to a mole fraction of sphingolipids X = 0.40) for both mixtures were constructed based on DSC and (2)H-NMR observations. For C(16)-ceramide-containing bilayers DSC heating scans showed already at X(cer) = 0.025 a complex structure of the main-phase transition peak suggestive of lateral-phase separation. The transition width increased significantly upon increasing X(cer), and the upper-phase boundary temperature of the mixture shifted to approximately 65 degrees C at X(cer) = 0.40. The temperature range over which (2)H-NMR spectra of C(16)-ceramide/DPPC-d(62) mixtures displayed coexistence of gel and liquid crystalline domains increased from approximately 10 degrees for X(cer) = 0.1 to approximately 21 degrees for X(cer) = 0.4. For C16-C1P/DPPC mixtures, DSC and (2)H-NMR observations indicated that two-phase coexistence was limited to significantly narrower temperature ranges for corresponding C1P concentrations. To complement these findings, C(16)-ceramide/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and C16-C1P/POPC mixtures were also studied by (2)H-NMR and fluorescence techniques. These observations indicate that DPPC and POPC bilayers are significantly less perturbed by C(16)-C1P than by C(16)-ceramide and that C(16)-C1P is miscible within DPPC bilayers at least up to X(C1P) = 0.30.

Ceramide–lipid interactions studied by MD simulations and solid-state NMR

“…Studies based on the fluorescence anisotropy have indicated that phospholipids tend to be more ordered in the presence of ceramides [20, 23, 25]; similar observations have been made using NMR, specifically for ceramides with 16-carbon chains, or C16-ceramide, in DPPC and POPC bilayers [21, 22, 27]. …”

Stratum corneum lipid liposome-encapsulated panomycocin: preparation, characterization, and the determination of antimycotic efficacy against <em>Candida</em> spp. isolated from patients with vulvovaginitis in an in vitro human vaginal epithelium tissue model

“…30 In the composition of SCLLs, ceramide is the lipid with the highest Tm value which is between 80°C and 90°C. 35 Since panomycocin is irreversibly inactive in this temperature range, we have used a modified freeze-thaw method in which the thawing was done at 4°C under vacuum 30 in order to preserve protein stability. The zeta potential values for empty and loaded liposomes were +22.0 and +21.4 mV, respectively, indicating a very low protein binding on the surface of the liposomes.…”

“…32 The high stability is most probably due to the long chain lipids with high phase transition temperatures found in the composition of SCLL structure, and this is also supported by the studies reporting a highly ordered structure and increased phase transition temperature for the lipid bilayers containing ceramides. 35,45 We have performed a biological efficacy test of the liposomal panomycocin formulation on an in vitro model of vaginal candidiasis. Liposomal lyophilized powder with predetermined panomycocin quantities for each Candida spp., which correspond to 1× MFC value of nonformulated pure panomycocin, was found to be inhibitory for all the tested strains.…”

NMR of liquid crystals and micellar solutions

“…The binary systems of N-hexadecanoyl-D-erythro-ceramide (C16-ceramide) or N-hexadecanoyl-D-erythro-ceramide-1-phosphate (C16-ceramide-1-phosphate; C16-C1P) with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) were studied with DSC and 2 H-NMR. 24 The effects of cholesterol on the thermotropic phase behavior and organization of aqueous dispersions of a homologous series of linear disaturated phosphatidylglycerols (PG) was investigated by DSC, FT-IR and and 31 P NMR spectroscopy. The incorporation of increasing quantities of cholesterol alters the temperature and progressively reduces the cooperativity of the gel-to-liquid-crystal phase transition of the host PG bilayer.…”