Sphingomyelin/cholesterol ratio: an important determinant of glucose transport mediated by GLUT-1 in 3T3-L1 preadipocytes

Al-Makdissy, Nehmann; Younsi, Mohamed; Pierre, Sidonie; Ziegler, O.; Donner, M.

doi:10.1016/s0898-6568(03)00070-6

Cited by 31 publications

(28 citation statements)

References 58 publications

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“…Overall, these results closely agree with the 50% decrease in plasma membrane cholesterol after treatment of astrocytes (8) or 3T3-L1 preadipocytes with bSMase (27). In contrast to our results, however, cholesterol levels recovered within 3 h in the continued presence of bSMase in preadipocytes.…”

Section: Discussionsupporting

confidence: 91%

Ceramide displaces cholesterol from lipid rafts and decreases the association of the cholesterol binding protein caveolin-1

Alterman

Dobrowsky

2005

Journal of Lipid Research

119

104

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Caveolae and lipid raft domains are distinct but related regions of the plasma membrane that are enriched in cholesterol, sphingomyelin, and glycosphingolipids (1, 2). Whereas lipid raft domains are present in many, if not all, cells (3), caveolae are specialized, morphologically distinct lipid raft domains that require the cell-specific expression of the protein caveolin-1 (Cav-1) (4).The integrity of lipid rafts is very dependent upon the presence of cholesterol (5). Relative to phospholipids, sphingolipids are more hydrophobic, undergo more hydrogen bonding, and tend to cluster within cell membranes (6). Moreover, the ability of cholesterol to pack tightly with saturated lipids is essential to promoting the liquid-ordered structure of lipid raft domains (6). The loss of cholesterol from caveolae by treatment with cholesterol-sequestering agents, through increased sterol oxidation, or by inhibiting its de novo synthesis leads to a more disordered state and the loss of raft-associated proteins. Indeed, because Cav-1 is a cholesterol binding protein, it is often used to monitor the loss of caveolar integrity after cholesterol displacement or depletion. Recent reports have provided evidence that ceramide production in raft model membranes and astrocytes causes a significant displacement of cholesterol from lipid raft membranes (7,8). However, whether a ceramide-induced displacement of cholesterol can lead to changes in the protein composition of caveolin-enriched membranes (CEMs) is unknown.The recent development of stable isotope labeling of cells in culture (SILAC) (9) has enabled a quantitative, hypothesis-driven assessment of changes in a single protein (10) as well as the unbiased, quantitative characterization of large proteomes (11). The basic premise of SILAC is that two populations of cells are grown in medium containing either unlabeled amino acids or an amino acid containing deuterium or 13 C substitutions. After a suffiAbbreviations: bSMase, bacterial sphingomyelinase; Cav-1, caveolin-1; CEM, caveolin-enriched membrane; dFCS, dialyzed fetal calf serum; MALDI-TOF MS, matrix-assisted laser desorption ionization time-of-flight mass spectrometry; M ␤ CD, methyl-␤ -cyclodextrin; SC, Schwann cell; SILAC, stable isotope labeling with amino acids in cell culture.

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Section: Discussionsupporting

confidence: 91%

Ceramide displaces cholesterol from lipid rafts and decreases the association of the cholesterol binding protein caveolin-1

Alterman

Dobrowsky

2005

Journal of Lipid Research

119

104

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“…In other words, DPH found itself in a more disordered lipid environment upon ceramide generation. The connection between DPH anisotropy and ceramide levels is direct, as anisotropy values returned to higher values in parallel with the reconversion of ceramide to SM (36). Our anisotropy data shows a similar relationship between DPH anisotropy and ceramide levels.…”

Section: Physiologically Relevant Ceramide Levels Displace Cholesterosupporting

confidence: 73%

“…There appears to be a direct relationship between these events. The rate of cholesterol displacement from the plasma membrane follows the rate of SM digestion without a significant time lag, and plasma membrane cholesterol levels recover at the same rate that SM is resynthesized from ceramide (2,36). Even the step in which internalized cholesterol is esterified follows ceramide generation within minutes (1,2,9).…”

Section: Physiologically Relevant Ceramide Levels Displace Cholesteromentioning

confidence: 99%

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Ceramide Selectively Displaces Cholesterol from Ordered Lipid Domains (Rafts)

Megha

London

2004

Journal of Biological Chemistry

377

274

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Ceramide is a membrane lipid involved in a number of crucial biological processes. Recent evidence suggests that ceramide is likely to reside and function within lipid rafts; ordered sphingolipid and cholesterol-rich lipid domains believed to exist within many eukaryotic cell membranes. Using lipid vesicles containing co-existing raft domains and disordered fluid domains, we find that natural and saturated synthetic ceramides displace sterols from rafts. Other raft lipids remain raft-associated in the presence of ceramide, showing displacement is relatively specific for sterols. Like cholesterol-containing rafts, ceramide-rich "rafts" remain in a highly ordered state. Comparison of the sterol-displacing abilities of natural ceramides with those of saturated diglycerides and an unsaturated ceramide demonstrates that tight lipid packing is critical for sterol displacement by ceramide. Based on these results, and the fact that cholesterol and ceramides both have small polar headgroups, we propose that ceramides and cholesterol compete for association with rafts because of a limited capacity of raft lipids with large headgroups to accommodate small headgroup lipids in a manner that prevents unfavorable contact between the hydrocarbon groups of the small headgroup lipids and the surrounding aqueous environment. Minimizing the exposure of cholesterol and ceramide to water may be a strong driving force for the association of other molecules with rafts. Furthermore, displacement of sterol from rafts by ceramide is very likely to have marked effects upon raft structure and function, altering liquid ordered properties as well as molecular composition. In this regard, certain previously observed physiological processes may be a result of displacement. In particular, a direct connection to the previously observed sphingomyelinase-induced displacement of cholesterol from plasma membranes in cells is proposed.

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“…36,47 It has also been previously reported that the various effects that are known to alter membrane fluidity altered the sensitivities of the regulation on the cell membrane transport, such as glucose transport and amino-acid transport. [48][49][50] Differences in membrane structure may be another explanation for the increase in DNP-SG transport of obese subjects. Further studies are therefore needed to evaluate the effect obesity on DNP-SG transport.…”

Section: Discussionmentioning

confidence: 99%

Increased glutathione conjugate transport: a possible compensatory protection mechanism against oxidative stress in obesity?

et al. 2005

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Objective: To compare glutathione S-conjugate transport in obese and nonobese persons, and how glutathione S-conjugates are involved in the antioxidant status in obesity. Materials and methods: The efflux of glutathione conjugates and malondialdehyde (MDA) levels were measured in erythrocytes of obese (N ¼ 33) and nonobese (N ¼ 28) persons at every 30 min during a 120 min incubation time in vitro. 2,4-dinitrophenyl-S-glutathione (DNP-SG) represented the glutathione S-conjugate. Results: The efflux of conjugate in erythrocytes from obese subjects (7087147 DNP-SG efflux nmol/ml erythrocytes/h) was significantly higher than that of control group (4907105 DNP-SG efflux nmol/ml erythrocytes/h) (Po0.05). At all time points measured (30-120 min), there was an increase in DNP-SG efflux in obese group (Po0.05). This is manifested by a decrease in cellular DNP-SG levels. The susceptibility of erythrocytes to in vitro 1-chloro-2,4-dinitrobenzene (CDNB)-induced oxidative stress were greater for cells of control group (Po0.05), although hemolysis sensitivity of these cells are not different between both groups (P40.05). Following CDNB pretreatment, incubation of erythrocyte with vanadate, a DNP-SG transport inhibitor, resulted in an increase of MDA in both groups. However, in this case, the difference in susceptibility was not related to obesity. On the other hand, while erythrocyte glutathione level was lower in obese subjects (79% of control) than in controls (Po0.05), the adenosine 5 0 -triphosphate (ATP) levels, the enzyme activities of glutathione S-transferase (GST) and the conjugation capacities of the erythrocytes were not different between groups (P40.05). Conclusion: Obesity may increase erythrocyte glutathione conjugate transport independent from ATP and GST activity that may protect against MDA formation in vitro.

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Sphingomyelin/cholesterol ratio: an important determinant of glucose transport mediated by GLUT-1 in 3T3-L1 preadipocytes

Cited by 31 publications

References 58 publications

Ceramide displaces cholesterol from lipid rafts and decreases the association of the cholesterol binding protein caveolin-1

Ceramide displaces cholesterol from lipid rafts and decreases the association of the cholesterol binding protein caveolin-1

Ceramide Selectively Displaces Cholesterol from Ordered Lipid Domains (Rafts)

Increased glutathione conjugate transport: a possible compensatory protection mechanism against oxidative stress in obesity?

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