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ABSTRACT: Bis(monoacylglycero)phosphate (BMP), also called lysobisphosphatidic acid, is a phospholipid highly enriched in the internal membranes of multivesicular late endosomes, in which it forms specialized lipid domains. It has been suggested that BMP-rich membranes regulate cholesterol transport. Here, we examine the effects of an anti-BMP antibody on cholesterol metabolism and transport in two macrophage cell lines, RAW 264.7 and THP-1, during loading with acetylated low density lipoprotein (AcLDL). Anti-BMP antibody was internalized and accumulated in both macrophage cell types. Cholesterol staining with filipin and mass measurements indicate that AcLDL-stimulated accumulation of free cholesterol (FC) was enhanced in macrophages that had accumulated the antibody. Unlike the hydrophobic amine U18666A (3-beta-[2-(diethylamino)ethoxy]androst-5-en-17-one), esterification of AcLDL-derived cholesterol by ACAT was not modified after anti-BMP treatment. AcLDL loading led to an increase of FC in the plasma membrane. This increase was further enhanced in anti-BMP-treated macrophages. However, cholesterol efflux to HDL was reduced in antibody-treated cells. These results suggest that the accumulation of anti-BMP antibody alters cholesterol homeostasis in AcLDL-loaded macrophages.
The Journal of Lipid Research 04/2007; 48(3):543-52. · 5.56 Impact Factor
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Tomohiro Hayakawa,
Yoshinori Hirano,
Asami Makino,
Sabine Michaud,
Michel Lagarde, Jean-François Pageaux,
Alain Doutheau,
Kazuki Ito,
Tetsuro Fujisawa,
Hiroshi Takahashi,
Toshihide Kobayashi
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ABSTRACT: Bis(monoacylglycero)phosphate (BMP) reveals an unusual sn-1,sn-1' stereoconfiguration of glycerophosphate. We synthesized sn-(3-myristoyl-2-hydroxy)glycerol-1-phospho-sn-1'-(3'-myristoyl-2'-hydroxy)glycerol (1,1'-DMBMP) and characterized the thermotropic phase behavior and membrane structure, in comparison with those of the corresponding sn-3:sn-1' stereoisomer (3,1'-DMBMP), by means of differential scanning calorimetry (DSC), small- and wide-angle X-ray scattering (SAXS and WAXS, respectively), pressure-area (pi-A) isotherms, epifluorescence microscopy of monolayers, and molecular dynamics (MD) simulations. In DSC, these lipids exhibited weakly energetic broad peaks with an onset temperature of 9 degrees C for 1,1'-DMBMP and 18 degrees C for 3,1'-DMBMP. In addition, a highly cooperative, strongly energetic transition peak was observed at approximately 40 degrees C for 1,1'-DMBMP and approximately 42 degrees C for 3,1'-DMBMP. These results are supported by the observation that 1,1'-DMBMP exhibited a larger phase transition pressure (pi(c)) than 3,1'-DMBMP. Small- and wide-angle X-ray scattering measurements identified these small and large energetic transitions as a quasi-crystalline (L(c1))-quasi-crystalline with different tilt angle (L(c2)) phase transition and an L(c2)-L(alpha) main phase transition, respectively. X-ray measurements also revealed that these DMBMPs undergo an unbinding at the main phase transition temperature. The MD simulations estimated stronger hydrogen bonding formation in the 3,1'-DMBMP membrane than in 1,1'-DMBMP, supporting the experimental data.
Biochemistry 09/2006; 45(30):9198-209. · 3.42 Impact Factor
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Karine Laulagnier,
Claude Motta,
Safouane Hamdi,
Sébastien Roy,
Florence Fauvelle, Jean-François Pageaux,
Toshihide Kobayashi,
Jean-Pierre Salles,
Bertrand Perret,
Christian Bonnerot,
Michel Record
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ABSTRACT: Exosomes are small vesicles secreted from multivesicular bodies, which are able to stimulate the immune system leading to tumour cell eradication. We have analysed lipids of exosomes secreted either upon stimulation from rat mast cells (RBL-2H3 cells), or constitutively from human dendritic cells. As compared with parent cells, exosomes displayed an enrichment in sphingomyelin, but not in cholesterol. Phosphatidylcholine content was decreased, but an enrichment was noted in disaturated molecular species as in phosphatidylethanolamines. Lyso(bis)phosphatidic acid was not enriched in exosomes as compared with cells. Fluorescence anisotropy demonstrated an increase in exosome-membrane rigidity from pH 5 to 7, suggesting their membrane reorganization between the acidic multivesicular body compartment and the neutral outer cell medium. NMR analysis established a bilayer organization of exosome membrane, and ESR studies using 16-doxyl stearic acid demonstrated a higher flip-flop of lipids between the two leaflets as compared with plasma membrane. In addition, the exosome membrane exhibited no asymmetrical distribution of phosphatidylethanolamines. Therefore exosome membrane displays a similar content of the major phospholipids and cholesterol, and is organized as a lipid bilayer with a random distribution of phosphatidylethanolamines. In addition, we observed tight lipid packing at neutral pH and a rapid flip-flop between the two leaflets of exosome membranes. These parameters could be used as a hallmark of exosomes.
Biochemical Journal 06/2004; 380(Pt 1):161-71. · 4.90 Impact Factor
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ABSTRACT: To gain some insight into the mechanisms involved in the opposing effects of arachidonic acid and docosahexaenoic acid on the growth of rat uterine stromal cells (UIIIcells), the dynamics of the uptake, conversion, and incorporation of labeled 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3), and 22:6(n-3) into lipid pools and phospholipid subclasses were examined. A very active and time-dependent conversion of [14C]18:3(n-3) to higher homologs was observed; 64.7 ± 0.7 and 11.5 ± 0.4% of the [14C] radioactivity incorporated in cellular lipids were recovered as 22:5(n-3) and 22:6(n-3) after 72 h incubation, respectively. The distribution of labeled fatty acids obtained after 72 h incubation with [3H]20:5(n-3) was not significantly different from that observed with 18:3(n-3). Arachidonic acid was the major fatty acid formed from [14C]18:2(n-6) and only trace amounts of 22:5(n-6) were detected. When cells were incubated for 72 h with 20:4(n-6), more than 75% of the radioactivity was recovered as arachidonate and slightly higher amounts of 22:4(n-6) and 22:5(n-6) were formed compared to those obtained after incubation with 18:2(n-6). Using both [14C]- and [3H]22:6(n-3), no significant retroconversion of labeled 22:6(n-3) occurred in the cells. More than 90% of labeled 20:4(n-6) and 22:6(n-3) taken up by the cells were esterified into phospholipids, but significant differences in their distribution among phospholipid classes and subclasses were observed. Docosahexaenoic acid was more rapidly and efficiently incorporated into phosphatidylethanolamine than 20:4(n-6) and was principally recovered in plasmalogens. Arachidonic acid was mainly incorporated in the diacyl subclasses of phosphatidylcholine and phosphatidylethanolamine and in phosphatidylinositol. The divergent distribution profiles of these two fatty acids within the phospholipid compartments provide some information for the mechanisms of their opposite effects on UIIIcell growth.
Archives of Biochemistry and Biophysics 04/1996; 327(1):142-150. · 2.93 Impact Factor
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ABSTRACT: The fatty acid (FA) compositions of plasma and oviduct phospholipids (PL) and triglycerides (TG) were studied throughout the
natural sexual development of the Japanese quail. In the oviduct, PL concentration increased rapidly during the period of
active oviduct cell proliferation and then remained at a constant level during the phase of cellular hypertrophy. Oviduct
and plasma TG concentrations were 2- and 10-fold higher, respectively, in fully developed animals than in immature ones. During
natural sexual maturation of the quail, the FA compositions of PL and TG were markedly modified both in plasma and in oviduct.
These qualitative changes occurred predominantly during the period of intense cellular proliferation of oviduct cells, and
also were observed in immature animals injected with physiological doses of estradiol. In oviduct PL, the proportions of 20∶4n−6
and 22∶4n−6 decreased significantly (from 20 to 10% and 3.5 to 0.7%, respectively) whereas those of 18∶2n−6 increased (from
8.5 to 21%). In contrast, the plasma PL proportions of 20∶4n−6, 22∶4n−6 and 18∶2n−6 were decreased significantly and the percentage
of 18∶1n−9 doubled, suggesting that the oviduct is able to utilize certain plasma FA to a greater extent than others. Changes
in plasma and oviduct lipid composition occurring in the quail during sexual development may be attributed to estradiol, which
stimulates hepatic Δ9 desaturase and inhibits the oviduct Δ6 desaturase. The changes in FA composition observed in oviduct
phospholipids are discussed in relation to eicosanoid production and cellular proliferation.
Lipids 04/1992; 27(7):518-525. · 2.13 Impact Factor
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ABSTRACT: The effects of tamoxifen on oviductal phospholipase A2 activity were studied in immature quails. Injected alone, from 0.1 to 10 mg/kg tamoxifen significantly reduced basal phospholipase A2 activity 6 h after the injection, independently of the dose used. At 24 h, maximal inhibition (-50%) was observed with 0.1 mg/kg tamoxifen, while higher doses were less effective. Combined with estradiol benzoate, tamoxifen reduced even below the control value (1 mg/kg for 24 h) the increase in phospholipase A2 activity induced by estrogen.
European Journal of Pharmacology.
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ABSTRACT: In rat uterine stromal cells (UIII cells), an oxidative stress induced by H2O2 caused a dose-dependent release of arachidonic acid (AA) that was independent of intracellular Ca2+ concentration and was not inhibited by Ca2+-dependent phospholipase A2 (cPLA2) inhibitors, nor by protein kinase C (PKC) inhibitors or by PKC down-regulation. H2O2 treatment did not impair AA esterification but significantly increased Ca2+-independent PLA2 (iPLA2) activity. Since iPLA2 specific inhibitor bromoenollactone almost completely suppressed the release of AA induced by H2O2, we conclude that iPLA2 activity represents the major mechanism by which H2O2 increases the availability of non-esterified AA in UIII cells. Moreover, PKC inhibitors sphingosine and calphostin C markedly potentiated the release of AA trigger by H2O2, suggesting a regulatory mechanism of iPLA2 by PKC that remains to be clarified.
Biochemical and Biophysical Research Communications.
