HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 20, 14868-14874, May 18, 2007

This Article Abstract Full Text (PDF) All Versions of this Article: 282/20/14868    most recent M611230200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nagao, K. Articles by Ueda, K. Search for Related Content PubMed PubMed Citation Articles by Nagao, K. Articles by Ueda, K. Social Bookmarking                      What's this?

Enhanced ApoA-I-dependent Cholesterol Efflux by ABCA1 from Sphingomyelin-deficient Chinese Hamster Ovary Cells^*

Kohjiro Nagao, Kei Takahashi, Kentaro Hanada, Noriyuki Kioka, Michinori Matsuo, and Kazumitsu Ueda¹

From the Laboratory of Cellular Biochemistry, Division of Applied Life Sciences, Kyoto University Graduate School of Agriculture, Kyoto 606-8502, Japan and Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan

Received for publication, December 7, 2006 , and in revised form, March 14, 2007.

	ABSTRACT

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
ATP binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high density lipoprotein (HDL) metabolism. It is proposed that ABCA1 reorganizes the plasma membrane and generates more loosely packed domains that facilitate apoA-I-dependent cholesterol efflux. In this study, we examined the effects of the cellular sphingomyelin level on HDL formation by ABCA1 by using a Chinese hamster ovary-K1 mutant cell line, LY-A, which has a missense mutation in the ceramide transfer protein CERT. When LY-A cells were cultured in Nutridoma-BO medium and sphingomyelin content was reduced, apoA-I-dependent cholesterol efflux by ABCA1 from LY-A cells increased 1.65-fold compared with that from LY-A/CERT cells stably transfected with human CERT cDNA. Exogenously added sphingomyelin significantly reduced the apoA-I-dependent efflux of cholesterol from LY-A cells, confirming that the decrease in sphingomyelin content in the plasma membrane stimulates cholesterol efflux by ABCA1. The amount of cholesterol available to cold methyl--cyclodextrin (MCD) extraction from LY-A cells was increased by 40% by the expression of ABCA1 and was 1.6-fold higher than that from LY-A/CERT cells. This step in ABCA1 function, making cholesterol available to cold MCD, was independent of apoA-I. These results suggest that the function of ABCA1 could be divided into two steps: (i) a flopping step to move phosphatidylcholine and cholesterol from the inner to outer leaflet of the plasma membrane, where cholesterol becomes available to cold MCD extraction, and (ii) a loading step to load phosphatidylcholine and cholesterol onto apoA-I to generate HDL.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
ATP binding cassette protein A1 (ABCA1)² plays a major role in cholesterol homeostasis and high density lipoprotein (HDL) metabolism (1). It has been reported that apolipoprotein A-I (apoA-I) binds to ABCA1 and cellular-free cholesterol (FC) and phospholipids (PL) are loaded onto apoA-I to form pre- HDL. It is clear that ABCA1 is involved in PL-rich HDL generation in plasma, because plasma PL concentration of Abca1^–/– mice was decreased by more than 75%, mostly due to a reduction of HDL (2); however, the molecular mechanism behind ABCA1-mediated pre-HDL formation is still poorly understood.

Several models have been proposed for the mechanism of ABCA1-mediated pre- HDL formation: (a) A two-step process model proposed by Fielding et al. (3) and Wang et al. (4) that ABCA1 first mediates PL efflux to apoA-I and this apolipoprotein-PL complex accepts FC in an ABCA1-independent manner; (b) a concurrent process model that FC and PL efflux by ABCA1 to apoA-I are tightly coupled to each other (5); and (c) a phosphatidylserine flopping model that ABCA1 mediates the translocation of phosphatidylserine to the outer leaflet and extracellular exposure of phosphatidylserine promotes apoA-I binding to the cell surface and subsequent translocation of phosphatidylcholine (PC) and cholesterol to apoA-I (6). To explore the mechanism of ABCA1-mediated pre- HDL formation, we purified human ABCA1 as a detergent-soluble form and examined ATPase activity (7). Purified ABCA1 showed robust ATPase activity when reconstituted in liposomes made of synthetic PC or sphingomyelin (SM), suggesting that ABCA1 recognizes PLs with choline head groups. As ATPase is reduced by the addition of cholesterol, we speculated that cholesterol also directly binds to ABCA1; however, the mechanism by which ABCA1 mediates lipid efflux to apoA-I has yet to be clarified.

Recently, Landry et al. (8) reported that ABCA1 reorganizes the plasma membrane and generates more loosely packed domains and suggested that the loosely packed domains facilitate apoA-I association with cells and, consequently, lipid acquisition by apoA-I to form nascent HDL particles. It was also reported that macrophages from ABCA1-deficient mice exhibited increased lipid rafts on the cell surface (9) and induction of ABCA1 by 8Br-cAMP made RAW264.7 cells more sensitive to MCD treatment (5). ABCA1 expression increased the Triton X-100 solubility of SM, but not that of PC (8). As SM has high affinity to cholesterol and tends to form raft domains in the plasma membrane, a change in SM content likely affects membrane dynamics. Indeed, it was reported that treating rat fibroblasts with SMase increased apoA-I- or apo-E-dependent cholesterol efflux (10); therefore, we hypothesized that reducing or redistributing SM is an ABCA1 function that facilitates apoA-I-dependent HDL formation.

In the present study, we analyzed apoA-I-dependent efflux of PLs and cholesterol from a Chinese hamster ovary-K1 mutant cell line, LY-A (11), which has a missense mutation in the ceramide transfer protein CERT, and examined the effects of the cellular SM level on HDL formation by ABCA1.

	EXPERIMENTAL PROCEDURES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
Materials—Anti-ABCA1 monoclonal antibody KM3110 was generated against the C-terminal 20 amino acids of ABCA1 in mice (12). Rabbit polyclonal anti-ABCG1 antibody was purchased from Santa Cruz Biotechnology. Rabbit polyclonal anti-caveolin-1 antibody was purchased from BD Transduction Laboratories. SM (99% from chicken egg yolk) and SMase (from Bacillus cereus) were purchased from Sigma. Sulfo-NHS-biotin was purchased from Pierce. TO901317 was purchased from Cayman Chemical. Recombinant apoA-I was prepared as reported previously (13). Other chemicals were purchased from Sigma, Amersham Biosciences, Wako Pure Chemical Industries, and Nacalai Tesque.

Cell Culture—The LY-A cell line is a Chinese hamster ovary-K1-derived mutant cell line defective in the endoplasmic reticulum-to-Golgi transport of ceramide (14), and the LY-A/CERT line is a stable transformant with human CERT cDNA. Ham's F-12 medium supplemented with 10% FBS was used as a normal culture medium. Nutridoma-BO medium (F-12 medium containing 1% Nutridoma-SP (Roche Applied Sciences), 0.1% FBS, and 10 µM sodium oleate/bovine serum albumin complex, and gentamicin (10 µg/ml)) was used as a sphingolipid-deficient culture medium (15). Chinese hamster ovary cells were maintained in the normal culture medium in a 5% CO₂ atmosphere in 100% humidity at 37 °C. For cultivation in a sphingolipid-deficient medium, cells were seeded, incubated in the normal culture medium at 37 °C for 24 h, and, after washing twice with PBS, cultured in Nutridoma-BO medium for 48 h.

Western Blotting—Cells were washed with PBS and lysed by lysis buffer (20 mM Tris-Cl, pH 7.5, 1 mM EDTA, 10% glycerol and 1% Triton X-100) containing protease inhibitors, 100 µg/ml (p-amidinophenyl)methanesulfonyl fluoride, 2 µg/ml leupeptin, and 2 µg/ml aprotinin. Samples were electrophoresed on SDS-polyacrylamide gel and immunodetected with the indicated antibodies.

Cellular Lipid Release Assay and MCD Extraction—Cells were cultured in F-12 containing 10% FBS and subcultured into 6-well plates at a density of 2 x 10⁵ cells. To deplete SM, cells were washed twice with PBS after a 24-h incubation and Nutridoma-BO medium was added. In 24 h, medium was exchanged with fresh Nutridoma-BO with or without 5 µM TO901317 and 5 µM 9 cis-retinoic acid (RA) to induce ABCA1 expression. After 24 h of incubation, cells were washed again twice with PBS and medium was exchanged to F-12 containing 0.02% bovine serum albumin, 5 µg/ml recombinant apoA-I, 5 µM TO901317, and 5 µM RA to analyze lipid release. The cholesterol and choline phospholipid content in the medium was determined after 6 h of incubation using colorimetric enzyme assays as described previously (16). To analyze the cholesterol available to cold MCD extraction, cells were washed twice with PBS and incubated with F-12 containing 5 mM MCD for 1 h on ice. The cholesterol content in the medium was determined as above.

Exogenous Addition of SM—SM was dissolved in 2:1 ethanol/Me₂SO to make a 5-mM stock. An aliquot of this stock solution was added to the culture medium (Nutridoma-BO) to make a final concentration of 40 µM as described previously (17), and cells were incubated for 12 h.

Cellular Lipid Content—The cell monolayer was washed twice with PBS, and cellular lipids were extracted with n-hexane/2-propanol (3:2). An aliquot of extracted lipids was subjected to analysis. The cholesterol and choline phospholipid content was determined as described above. The SM content was determined as described previously by Hojjati et al. (18). Extracted lipids were incubated with bacterial SMase, alkaline phosphatase, choline oxidase, peroxidase, N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3,5-dimethoxyaniline, and 4-aminoantipyrine for 45 min. The absorbance at 595 nm of generated blue dye was measured with a spectrophotometer (Bio-Rad). The specificity of this assay to SM was confirmed (data not shown).

Triton X-100 Extraction—Cellular content of Triton X-100 (TX)-soluble cholesterol was analyzed as described previously (8). Briefly, cell monolayers were washed twice with ice-cold PBS and chilled on ice for 30 min in F-12 containing 10 mM HEPES, pH 7.4. The medium was then replaced with 1 ml/well F12/HEPES in the presence of 1% Triton X-100 and further incubated on ice for 30 min. The medium was then collected, and the first wash with 500 µl of ice-cold PBS was combined with medium. The cholesterol content in the medium (TX-soluble) and cells (TX-insoluble) was determined as described above. Distribution of ABCA1 between TX-soluble and TX-insoluble membranes was determined as reported (19, 20). Cells were washed with PBS and lysed by MES-buffered saline (25 mM MES, pH 6.5, 0.15 M NaCl) containing 1% Triton X-100 and protease inhibitors. The suspension was kept on ice for 20 min and centrifuged at 14,000 x g for 20 min at 4 °C. The supernatant (TX-soluble) was removed. The pellet (TX-insoluble) was suspended in HEPES-buffered saline (25 mM HEPES, pH 7.4, 0.15 M NaCl) containing 1% Triton X-100 and protease inhibitors and solubilized by sonication.

Biotinylation of Cell Surface Proteins—Cell monolayers were kept on ice for 10 min. Cells were washed with ice-cold PBS⁺ (phosphate-buffered saline containing 0.1 mg/ml CaCl₂ and MgCl₂6H₂O) and incubated with 0.5 mg/ml sulfo-NHS-biotin solubilized in PBS⁺ for 30 min on ice in the dark. Cells were washed with PBS⁺ to remove unbound sulfo-NHS-biotin and lysed in radioimmune precipitation buffer (20 mM Tris-Cl, pH 7.5, 1% Triton X-100, 0.1% SDS, and 1% sodium deoxycholate) containing protease inhibitors. Immobilized monomeric avidin gel (Pierce) was added to the cell lysate to precipitate biotinylated proteins, which were electrophoresed on a 7% SDS-polyacrylamide gel and immunodetected.

Protein Assay—Cell monolayers were incubated in 0.1 N NaOH for 1 h at room temperature. A protein assay was performed with BCA protein assay reagent (Pierce).

Statistical Analysis—Values are presented as the means ± S.E. Statistical significance was determined by Student's t test. A value of p < 0.05 was considered statistically significant.

	RESULTS

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
ApoA-I-dependent Efflux of PLs from LY-A Cells—To examine the effect of cellular SM content on the function of ABCA1, efflux of PLs from LY-A and LY-A/CERT cells was analyzed in the presence and absence of apoA-I. Because of a mutation in the ceramide transfer protein CERT, LY-A cells are defective in de novo synthesis of SM (11). Indeed, when LY-A cells were cultured in a sphingolipid-deficient medium, SM content in LY-A cells became 65% that of LY-A/CERT cells (Table 1). The amount of choline phospholipid and total cholesterol content of these cells was not significantly changed. When these cells were cultured in F-12 medium containing 10% FBS, there was no difference in SM, PC and cholesterol content between LY-A and LY-A/CERT cells (data not shown). The expression of ABCA1 was induced by a liver X receptor agonist, TO901317, and a retinoid X receptor agonist, RA. Treatment with these compounds did not affect SM and FC content in either cells (Table 1). PL content was slightly increased by the treatment, but there was no difference between LY-A and LY-A/CERT cells. The efflux of PLs from both LY-A and LY-A/CERT cells was strongly stimulated in the presence of apoA-I compared with that in its absence (Fig. 1). When cells were cultured in the sphingolipid-deficient medium (Fig. 1A), the amount of PL excreted from LY-A cells in the presence of apoA-I was significantly higher (by 51%) than that from LY-A/CERT cells, although there was no difference in the PL excretion between the two cell types when cells were cultured in medium containing 10% FBS (Fig. 1B). LY-A and LY-A/CERT cells cultured in medium containing 10% FBS showed higher efflux of PL than those cultured in Nutridoma-BO medium. Because culture conditions did not affect the expression level of ABCA1 in these cells (data not shown), the higher efflux may be attributed to good growth rate or culture conditions.

View larger version (17K): [in this window] [in a new window]   FIGURE 1. Efflux of choline phospholipids from LY-A and LY-A/CERT cells. Cells were cultured in Nutridoma-BO medium (A) or in F-12 medium containing 10% FBS (B) for 48 h. The expression of ABCA1 was induced by incubation with TO901317 and RA for 24 h. The efflux of choline phospholipids during 6 h in the absence (open bars) or presence (filled bars) of apoA-I (5 µg) was analyzed. Experiments were performed in triplicate, and the average values are represented with the S.E.

View larger version (69K): [in this window] [in a new window]   FIGURE 2. Total and cell surface expression of ABCA1 in LY-A and LY-A/CERT cells. Cells were cultured in Nutridoma-BO medium for 48 h. The expression of ABCA1 was induced by incubation with TO901317 and RA for 24 h. A, cell lysates (5 µg of protein) were separated by 7% polyacrylamide gel electrophoresis, and ABCA1 was detected with anti-ABCA1 antibody KM3110 (12). The amount of vinculin was analyzed as a loading control. B, cells were treated with sulfo-NHS-biotin, and cell lysates were prepared. Biotinylated surface proteins were precipitated with avidin-agarose from 150 µg of cell lysates. Cell lysates (5 µg of protein, upper panel) and precipitated surface proteins (lower panel) were separated and detected with KM3110.

View larger version (16K): [in this window] [in a new window]   FIGURE 3. Efflux of cholesterol from LY-A and LY-A/CERT cells. Cells were cultured in Nutridoma-BO medium (A) or in F-12 medium containing 10% FBS (B) for 48 h. The expression of ABCA1 was induced by TO901317 and RA for 24 h. The efflux of cholesterol from LY-A and LY-A/CERT cells during 6 h in the absence (open bars) or presence (filled bars) of apoA-I (5 µg) was analyzed. The efflux of cholesterol was also analyzed in the presence of 20 µg of apoA-I, and the higher cholesterol efflux from LY-A cells was observed (data not shown). Experiments were performed in triplicate, and the average values are represented with the S.E.

View larger version (15K): [in this window] [in a new window]   FIGURE 4. Effect of exogenously added sphingomyelin on efflux of cholesterol from LY-A cells. Cells were cultured in Nutridoma-BO medium for 48 h. The expression of ABCA1 was induced by TO901317 and RA for 24 h. Sphingomyelin (40 µM) was added to the medium for 12 h. The efflux of cholesterol from LY-A cells during 6 h in the absence (open bars) or presence (filled bars) of apoA-I (5 µg) was analyzed. Experiments were performed in triplicate, and the average values are represented with the S.E.

View larger version (17K): [in this window] [in a new window]   FIGURE 5. Cholesterol extraction by cold MCD from LY-A and LY-A/CERT cells. Cells were cultured in Nutridoma-BO medium for 48 h. The expression of ABCA1 was induced by TO901317 and RA for 24 h. Cholesterol extracted by the medium with (filled bars) or without (open bars) 5 mM MCD on ice for 1 h was analyzed. Experiments were performed in triplicate, and the average values are represented with the S.E. *, p < 0.05; **, p < 0.01.

View larger version (16K): [in this window] [in a new window]   FIGURE 6. Effect of exogenously added sphingomyelin on MCD extraction of cholesterol from LY-A cells. Cells were cultured in Nutridoma-BO medium for 48 h. The expression of ABCA1 was induced by TO901317 and RA for 24 h. Sphingomyelin (40 µM) was added to the medium for 12 h. Cholesterol extracted by the medium with 5 mM MCD on ice for 1 h was analyzed. No cholesterol was observed in the medium without MCD. Experiments were performed in triplicate, and the average values are represented with the S.E. *, p < 0.05; **, p < 0.01; ***, p < 0.001.

Distribution of ABCA1 and Cholesterol in TX-soluble Membranes—The distribution of ABCA1 and cholesterol between TX-soluble and TX-insoluble fractions was examined. ABCA1 was recovered from TX-soluble membranes as previously reported (19), whereas caveolin-1, a raft-specific protein, was recovered from TX-insoluble membranes (Fig. 7A). Under these experimental conditions, significantly more cholesterol was recovered in the TX-soluble fraction from LY-A cells than from LY-A/CERT cells (Fig. 7B).

	DISCUSSION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
In this study, we have demonstrated that the SM level in the plasma membrane affects apoA-I-dependent efflux of PL and cholesterol mediated by ABCA1. When LY-A cells were cultured in Nutridoma-BO medium, the SM content in LY-A cells became 65% that of LY-A/CERT cells, whereas choline phospholipid and the total cholesterol content of these cells was not changed. Under these conditions, apoA-I-dependent cholesterol efflux by ABCA1 from LY-A cells was 1.65-fold higher than that from LY-A/CERT cells. Exogenously added SM reduced apoA-I-dependent efflux of cholesterol from LY-A cells, confirming that decrease in SM content in the plasma membrane stimulates cholesterol efflux by ABCA1.

View larger version (31K): [in this window] [in a new window]   FIGURE 7. Distribution of ABCA1 and cholesterol between TX-soluble or -insoluble membranes. Cells were cultured in Nutridoma-BO medium for 48 h. The expression of ABCA1 was induced by TO901317 and RA for 24 h. A, TX-soluble (S) and TX-insoluble (IS) proteins (5 µg), isolated as described under "Experimental Procedures," were separated by 7 or 15% polyacrylamide gel electrophoresis. ABCA1 and caveolin-1 (raft marker) were detected with specific antibodies. The experiment was repeated, and similar results were obtained. B, TX-extracted cholesterol was analyzed as described under "Experimental Procedures." The results are presented as percentage TX-soluble FC of total FC (TX-soluble plus TX-insoluble). Experiments were performed in triplicate, and the average values are represented with the S.E.

Importantly, this action of ABCA1 is independent of apoA-I. It was reported that overexpression of ABCA1 in baby hamster kidney cells in the absence of apoA-I redistributed membrane cholesterol to cell surface domains accessible to treatment with the enzyme cholesterol oxidase (21). ABCA1 may redistribute cholesterol to cell surface domains, such as non-raft domains, because the action of cholesterol oxidase on membrane cholesterol was reported to highly depend on the environment of the substrate and loosely packed cholesterol is likely more accessible to oxidase (22). Alternatively, ABCA1 may actively flop cholesterol from the inner to outer leaflet of the membrane, which makes cholesterol more accessible to cholesterol oxidase and available to cold MCD extraction. The result by Landry et al., showing that a non-functional ABCA1 with mutation in the ATP-binding domain A937V fails to redistribute cholesterol, may support the latter model. These results suggest that the function of ABCA1 could be divided into two steps: (i) to flop PC and cholesterol from the inner to outer leaflet of the plasma membrane, and (ii) to load cholesterol onto apoA-I. The first step (flopping step) makes cholesterol available to cold MCD extraction and to reorganize membrane domains. As cholesterol available to cold MCD cannot be loaded onto apoA-I spontaneously, the second step (loading step) should be also mediated by ABCA1.

Notably, not only cholesterol but also more PL was loaded onto apoA-I from LY-A when cultured in Nutridoma-BO medium (Fig. 1A). Under these conditions, more cholesterol was recovered in the TX-soluble fraction from LY-A cells than from LY-A/CERT cells and ABCA1 is distributed in TX-soluble membranes (Fig. 7). ABCA1 may preferentially function in non-raft domains containing more PC and less SM as reported by Mendez et al. (19). Recently, we reported that purified ABCA1 shows the highest ATPase activity when reconstituted in liposomes made of synthetic PC or SM (7). Alternatively, PC may be the more favorable substrate for ABCA1 to transport with cholesterol. Indeed, the medium of ABCA1-expressing cells contains more PC species than SM species in the presence of apoA-I (23).

We also analyzed the function of ABCG1 by using LY-A and LY-A/CERT cells.³ We transiently expressed human ABCG1 in these cells and analyzed the efflux of cholesterol and SM mediated by ABCG1. Interestingly, ABCG1-mediated cholesterol efflux from LY-A cells was reduced as opposed to ABCA1-mediated cholesterol efflux. These results may suggest that ABCG1-mediated cholesterol efflux occurs in raft domains whereas ABCA1-mediated cholesterol efflux occurs in non-raft domains. Alternatively, ABCG1 may recognize cholesterol with SM as substrates to transport, whereas ABCA1 recognizes cholesterol with PC as substrates to transport.

In conclusion, we analyzed the function of ABCA1 by using CERT-deficient Chinese hamster ovary-K1 cells and demonstrated that the SM level in the plasma membrane affects the apoA-I-dependent efflux of PL and cholesterol. The effect of the reduction of plasma membrane SM content on the function of ABCA1 was quite different from that on the function of ABCG1. From these results, we propose a two-step (flopping and loading) model for ABCA1 function. Because ABCG1-mediated SM efflux (23) would reduce SM content in the plasma membrane, co-expression of ABCG1 on the same cell surface with ABCA1 may facilitate cholesterol efflux by ABCA1 to generate HDL. Further studies are needed to verify these models, but this study would facilitate our understanding of the mechanism of cholesterol efflux mediated by ABC transporters involved in cholesterol homeostasis.

	FOOTNOTES

 
^* This work was supported by Grant-in-aid for Scientific Research and Creative Scientific Research 15GS0301 from the Ministry of Education, Culture, Sports, Science, and Technology, Japan, and grants from the Bio-oriented Technology Research Advancement Institution and the Pharmaceutical and Medical Devices Agency. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed. Tel.: 81-75-753-6124; Fax: 81-75-753-6104; E-mail: uedak{at}kais.kyoto-u.ac.jp.

² The abbreviations used are: ABC, ATP binding cassette; apoA-I, apolipoprotein A-I; FBS, fetal bovine serum; FC, free cholesterol; HDL, high density lipoprotein; MCD, methyl--cyclodextrin; MES, 4-morpholineethanesulfonic acid; PBS, phosphate-buffered saline; PC, phosphatidylcholine; PL, phospholipids; RA, 9 cis-retinoic acid; SM, sphingomyelin; sulfo-NHS-biotin, sulfo-N-hydroxysuccinimidobiotin; TX, Triton X-100.

³ O. Sano, A. Kobayashi, K. Nagao, K. Kumagai, N. Kioka, K. Hanada, K. Ueda, and M. Matsuo, submitted for publication.

	REFERENCES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 

1. Tanaka, A. R., Abe-Dohmae, S., Ohnishi, T., Aoki, R., Morinaga, G., Okuhira, K. I., Ikeda, Y., Kano, F., Matsuo, M., Kioka, N., Amachi, T., Murata, M., Yokoyama, S., and Ueda, K. (2003) J. Biol. Chem. 278, 8815–8819[Abstract/Free Full Text]
2. Francone, O. L., Subbaiah, P. V., van Tol, A., Royer, L., and Haghpassand, M. (2003) Biochemistry 42, 8569–8578[CrossRef][Medline] [Order article via Infotrieve]
3. Fielding, P. E., Nagao, K., Hakamata, H., Chimini, G., and Fielding, C. J. (2000) Biochemistry 39, 14113–14120[CrossRef][Medline] [Order article via Infotrieve]
4. Wang, N., Silver, D. L., Thiele, C., and Tall, A. R. (2001) J. Biol. Chem. 276, 23742–23747[Abstract/Free Full Text]
5. Smith, J. D., Le Goff, W., Settle, M., Brubaker, G., Waelde, C., Horwitz, A., and Oda, M. N. (2004) J. Lipid Res. 45, 635–644[Abstract/Free Full Text]
6. Hamon, Y., Broccardo, C., Chambenoit, O., Luciani, M. F., Toti, F., Chaslin, S., Freyssinet, J. M., Devaux, P. F., McNeish, J., Marguet, D., and Chimini, G. (2000) Nat. Cell Biol. 2, 399–406[CrossRef][Medline] [Order article via Infotrieve]
7. Takahashi, K., Kimura, Y., Kioka, N., Matsuo, M., and Ueda, K. (2006) J. Biol. Chem. 281, 10760–10768[Abstract/Free Full Text]
8. Landry, Y. D., Denis, M., Nandi, S., Bell, S., Vaughan, A. M., and Zha, X. (2006) J. Biol. Chem. 281, 36091–36101[Abstract/Free Full Text]
9. Koseki, M., Hirano, K. I., Masuda, D., Ikegami, C., Tanaka, M., Ota, A., Sandoval, J. C., Nakagawa-Toyama, Y., Sato, S. B., Kobayashi, T., Shimada, Y., Ohno-Iwashita, Y., Matsuura, F., Shimomura, I., and Yamashita, S. (2007) J. Lipid Res. 48, 299–306[Abstract/Free Full Text]
10. Ito, J.-I., Nagayasu, Y., and Yokoyama, S. (2000) J. Lipid Res. 41, 894–904[Abstract/Free Full Text]
11. Hanada, K., Hara, T., Fukasawa, M., Yamaji, A., Umeda, M., and Nishijima, M. (1998) J. Biol. Chem. 273, 33787–33794[Abstract/Free Full Text]
12. Munehira, Y., Ohnishi, T., Kawamoto, S., Furuya, A., Shitara, K., Imamura, M., Yokota, T., Takeda, S., Amachi, T., Matsuo, M., Kioka, N., and Ueda, K. (2004) J. Biol. Chem. 279, 15091–15095[Abstract/Free Full Text]
13. Ohta, K., Shibui, T., Morimoto, Y., IIjima, S., and Kobayashi, T. (1993) J. Ferment. Bioeng. 75, 155–157[CrossRef]
14. Hanada, K., Kumagai, K., Yasuda, S., Miura, Y., Kawano, M., Fukasawa, M., and Nishijima, M. (2003) Nature 426, 803–809[CrossRef][Medline] [Order article via Infotrieve]
15. Hanada, K., Nishijima, M., Kiso, M., Hasegawa, A., Fujita, S., Ogawa, T., and Akamatsu, Y. (1992) J. Biol. Chem. 267, 23527–23533[Abstract/Free Full Text]
16. Abe-Dohmae, S., Suzuki, S., Wada, Y., Aburatani, H., Vance, D. E., and Yokoyama, S. (2000) Biochemistry 39, 11092–11099[CrossRef][Medline] [Order article via Infotrieve]
17. Puri, V., Jefferson, J. R., Singh, R. D., Wheatley, C. L., Marks, D. L., and Pagano, R. E. (2003) J. Biol. Chem. 278, 20961–20970[Abstract/Free Full Text]
18. Hojjati, M. R., and Jiang, X. C. (2006) J. Lipid Res. 47, 673–676[Abstract/Free Full Text]
19. Mendez, A. J., Lin, G., Wade, D. P., Lawn, R. M., and Oram, J. F. (2001) J. Biol. Chem. 276, 3158–3166[Abstract/Free Full Text]
20. Brown, D. A., and Rose, J. K. (1992) Cell 68, 533–544[CrossRef][Medline] [Order article via Infotrieve]
21. Vaughan, A. M., and Oram, J. F. (2003) J. Lipid Res. 44, 1373–1380[Abstract/Free Full Text]
22. Wang, M. M., Olsher, M., Sugar, I. P., and Chong, P. L. (2004) Biochemistry 43, 2159–2166[CrossRef][Medline] [Order article via Infotrieve]
23. Kobayashi, A., Takanezawa, Y., Hirata, T., Shimizu, Y., Misasa, K., Kioka, N., Arai, H., Ueda, K., and Matsuo, M. (2006) J. Lipid Res. 47, 1791–1802[Abstract/Free Full Text]

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				K. Nagao, Y. Zhao, K. Takahashi, Y. Kimura, and K. Ueda Sodium taurocholate-dependent lipid efflux by ABCA1: effects of W590S mutation on lipid translocation and apolipoprotein A-I dissociation J. Lipid Res., June 1, 2009; 50(6): 1165 - 1172. [Abstract] [Full Text] [PDF]

				J. Liu, H. Zhang, Z. Li, T. K. Hailemariam, M. Chakraborty, K. Jiang, D. Qiu, H. H. Bui, D. A. Peake, M.-S. Kuo, et al. Sphingomyelin Synthase 2 Is One of the Determinants for Plasma and Liver Sphingomyelin Levels in Mice Arterioscler. Thromb. Vasc. Biol., June 1, 2009; 29(6): 850 - 856. [Abstract] [Full Text] [PDF]

				Y. Azuma, M. Takada, H.-W. Shin, N. Kioka, K. Nakayama, and K. Ueda Retroendocytosis pathway of ABCA1/apoA-I contributes to HDL formation. Genes Cells, February 1, 2009; 14(2): 191 - 204. [Abstract] [Full Text] [PDF]

				N. Mukhamedova, G. Escher, W. D'Souza, U. Tchoua, A. Grant, Z. Krozowski, M. Bukrinsky, and D. Sviridov Enhancing apolipoprotein A-I-dependent cholesterol efflux elevates cholesterol export from macrophages in vivo J. Lipid Res., November 1, 2008; 49(11): 2312 - 2322. [Abstract] [Full Text] [PDF]

				A. J. Murphy, K. J. Woollard, A. Hoang, N. Mukhamedova, R. A. Stirzaker, S. P.A. McCormick, A. T. Remaley, D. Sviridov, and J. Chin-Dusting High-Density Lipoprotein Reduces the Human Monocyte Inflammatory Response Arterioscler. Thromb. Vasc. Biol., November 1, 2008; 28(11): 2071 - 2077. [Abstract] [Full Text] [PDF]

				K. Bowden and N. D. Ridgway OSBP Negatively Regulates ABCA1 Protein Stability J. Biol. Chem., June 27, 2008; 283(26): 18210 - 18217. [Abstract] [Full Text] [PDF]

				T. Ding, Z. Li, T. Hailemariam, S. Mukherjee, F. R. Maxfield, M.-P. Wu, and X.-C. Jiang SMS overexpression and knockdown: impact on cellular sphingomyelin and diacylglycerol metabolism, and cell apoptosis J. Lipid Res., February 1, 2008; 49(2): 376 - 385. [Abstract] [Full Text] [PDF]

				O. Sano, A. Kobayashi, K. Nagao, K. Kumagai, N. Kioka, K. Hanada, K. Ueda, and M. Matsuo Sphingomyelin-dependence of cholesterol efflux mediated by ABCG1 J. Lipid Res., November 1, 2007; 48(11): 2377 - 2384. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) All Versions of this Article: 282/20/14868    most recent M611230200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nagao, K. Articles by Ueda, K. Search for Related Content PubMed PubMed Citation Articles by Nagao, K. Articles by Ueda, K. Social Bookmarking                      What's this?