Background Dyslipidemia associated with obesity often manifests as increased plasma LDL and triglyceride-rich lipoprotein levels suggesting changes in hepatic lipoprotein receptor status. Persistent organic pollutants have been recently postulated to contribute to the obesity etiology by increasing adipogenesis, but little information is available on their potential effect on hepatic lipoprotein metabolism. Objective The objective of this study was to investigate the effect of the common environmental pollutant, benzo[α]pyrene (B[α]P) on two lipoprotein receptors, the LDL-receptor and the lipolysis-stimulated lipoprotein receptor (LSR) as well as the ATP-binding cassette transporter A1 (ABCA1) using cell and animal models. Results LSR, LDL-receptor as well as ABCA1 protein levels were significantly decreased by 26–48% in Hepa1-6 cells incubated (<2 h) in the presence of B[α]P (≤1 μM). Real-time PCR analysis and lactacystin studies revealed that this effect was due primarily to increased proteasome, and not lysosomal-mediated degradation rather than decreased transcription. Furthermore, ligand blots revealed that lipoproteins exposed to 1 or 5 μM B[α]P displayed markedly decreased (42–86%) binding to LSR or LDL-receptor. B[α]P-treated (0.5 mg/kg/48 h, i.p. 15 days) C57BL/6J mice displayed higher weight gain, associated with significant increases in plasma cholesterol, triglycerides, and liver cholesterol content, and decreased hepatic LDL-receptor and ABCA1 levels. Furthermore, correlational analysis revealed that B[α]P abolished the positive association observed in control mice between the LSR and LDL-receptor. Interestingly, levels of other proteins involved in liver cholesterol metabolism, ATP-binding cassette transporter G1 and scavenger receptor-BI, were decreased, while those of acyl-CoA:cholesterol acyltransferase 1 and 2 were increased in B[α]P-treated mice. Conclusions B[α]P demonstrates inhibitory action on LSR and LDL-R, as well as ABCA1, which we propose leads to modified lipid status in B[α]P-treated mice, thus providing new insight into mechanisms underlying the involvement of pollutants in the disruption of lipid homeostasis, potentially contributing to dyslipidemia associated with obesity.
References
[1]
Caballero B (2007) The global epidemic of obesity: an overview. Epidemiol Rev 29: 1–5. doi: 10.1093/epirev/mxm012
[2]
Cunningham E (2010) Where can I find obesity statistics? J Am Diet Assoc 110: 656. doi: 10.1016/j.jada.2010.02.023
[3]
Howard BV, Ruotolo G, Robbins DC (2003) Obesity and dyslipidemia. Endocrinol Metab Clin North Am 32: 855–867. doi: 10.1016/s0889-8529(03)00073-2
[4]
Eckel RH (2011) The complex metabolic mechanisms relating obesity to hypertriglyceridemia. Arterioscler Thromb Vasc Biol 31: 1946–1948. doi: 10.1161/atvbaha.111.233049
[5]
Brown MS, Goldstein JL (1986) A receptor-mediated pathway for cholesterol homeostasis. Science 232: 34–47. doi: 10.1126/science.3513311
[6]
Narvekar P, Berriel Diaz M, Krones-Herzig A, Hardeland U, Strzoda D, et al. (2009) Liver-specific loss of lipolysis-stimulated lipoprotein receptor triggers systemic hyperlipidemia in mice. Diabetes 58: 1040–1049. doi: 10.2337/db08-1184
[7]
Stenger C, Corbier C, Yen FT (2012) Structure and function of the lipolysis stimulated lipoprotein receptor. In: D Ekinci, editor editors. Chemical Biology. Rijeka: InTech. pp. 267–292.
[8]
Yen FT, Roitel O, Bonnard L, Notet V, Pratte D, et al. (2008) Lipolysis stimulated lipoprotein receptor: a novel molecular link between hyperlipidemia, weight gain, and atherosclerosis in mice. J Biol Chem 283: 25650–25659. doi: 10.1074/jbc.m801027200
[9]
Schreyer SA, Vick C, Lystig TC, Mystkowski P, LeBoeuf RC (2002) LDL receptor but not apolipoprotein E deficiency increases diet-induced obesity and diabetes in mice. Am J Physiol Endocrinol Metab 282: E207–214.
[10]
Stenger C, Hanse M, Pratte D, Mbala ML, Akbar S, et al. (2010) Up-regulation of hepatic lipolysis stimulated lipoprotein receptor by leptin: a potential lever for controlling lipid clearance during the postprandial phase. Faseb J 24: 4218–4228. doi: 10.1096/fj.10-160440
[11]
Heindel JJ, vom Saal FS (2009) Role of nutrition and environmental endocrine disrupting chemicals during the perinatal period on the aetiology of obesity. Mol Cell Endocrinol 304: 90–96. doi: 10.1016/j.mce.2009.02.025
Hao C, Cheng X, Xia H, Ma X (2012) The endocrine disruptor mono-(2-ethylhexyl) phthalate promotes adipocyte differentiation and induces obesity in mice. Biosci Rep 32: 619–629. doi: 10.1042/bsr20120042
[14]
Sargis RM, Johnson DN, Choudhury RA, Brady MJ (2010) Environmental endocrine disruptors promote adipogenesis in the 3T3-L1 cell line through glucocorticoid receptor activation. Obesity (Silver Spring) 18: 1283–1288. doi: 10.1038/oby.2009.419
[15]
Bostrom CE, Gerde P, Hanberg A, Jernstrom B, Johansson C, et al. (2002) Cancer risk assessment, indicators, and guidelines for polycyclic aromatic hydrocarbons in the ambient air. Environ Health Perspect 110 Suppl 3451–488. doi: 10.1289/ehp.02110s3451
[16]
Brevik A, Lindeman B, Rusnakova V, Olsen AK, Brunborg G, et al. (2012) Paternal benzo[α]pyrene exposure affects gene expression in the early developing mouse embryo. Toxicol Sci 129: 157–165. doi: 10.1093/toxsci/kfs187
[17]
Palanikumar L, Kumaraguru AK, Ramakritinan CM, Anand M (2011) Biochemical response of anthracene and benzo [α] pyrene in milkfish Chanos chanos. Ecotoxicol Environ Saf 75: 187–197. doi: 10.1016/j.ecoenv.2011.08.028
[18]
EFSA (2008) Scientific opinion of the panel on contaminants in the food chain on a request from the European Commission on polycyclic aromatic hydrocarbons in food. The EFSA Journal 724: 1–114.
[19]
Hutcheon DE, Kantrowitz J, Van Gelder RN, Flynn E (1983) Factors affecting plasma benzo[α]pyrene levels in environmental studies. Environ Res 32: 104–110. doi: 10.1016/0013-9351(83)90196-2
[20]
Irigaray P, Ogier V, Jacquenet S, Notet V, Sibille P, et al. (2006) Benzo[α]pyrene impairs beta-adrenergic stimulation of adipose tissue lipolysis and causes weight gain in mice. A novel molecular mechanism of toxicity for a common food pollutant. Febs J 273: 1362–1372. doi: 10.1111/j.1742-4658.2006.05159.x
[21]
Boysen G, Hecht SS (2003) Analysis of DNA and protein adducts of benzo[α]pyrene in human tissues using structure-specific methods. Mutat Res 543: 17–30. doi: 10.1016/s1383-5742(02)00068-6
[22]
Ekstrom G, von Bahr C, Glaumann H, Ingelman-Sundberg M (1982) Interindividual variation in benzo(a)pyrene metabolism and composition of isoenzymes of cytochrome P-450 as revealed by SDS-gel electrophoresis of human liver microsomal fractions. Acta Pharmacol Toxicol (Copenh) 50: 251–260. doi: 10.1111/j.1600-0773.1982.tb00971.x
[23]
Mitchell CE, Fischer JP, Dahl AR (1987) Differential induction of cytochrome P-450 catalyzed activities by polychlorinated biphenyls and benzo [α]pyrene in B6C3F1 mouse liver and lung. Toxicology 43: 315–323. doi: 10.1016/0300-483x(87)90090-4
[24]
Fujisawa-Sehara A, Yamane M, Fujii-Kuriyama Y (1988) A DNA-binding factor specific for xenobiotic responsive elements of P-450c gene exists as a cryptic form in cytoplasm: its possible translocation to nucleus. Proc Natl Acad Sci U S A 85: 5859–5863. doi: 10.1073/pnas.85.16.5859
[25]
Schmidt JV, Bradfield CA (1996) Ah receptor signaling pathways. Annu Rev Cell Dev Biol 12: 55–89. doi: 10.1146/annurev.cellbio.12.1.55
[26]
Shimizu Y, Nakatsuru Y, Ichinose M, Takahashi Y, Kume H, et al. (2000) Benzo[α]pyrene carcinogenicity is lost in mice lacking the aryl hydrocarbon receptor. Proc Natl Acad Sci U S A 97: 779–782. doi: 10.1073/pnas.97.2.779
[27]
Busbee DL, Norman JO, Ziprin RL (1990) Comparative uptake, vascular transport, and cellular internalization of aflatoxin-B1 and benzo(a)pyrene. Arch Toxicol 64: 285–290. doi: 10.1007/bf01972988
[28]
Vauhkonen M, Kuusi T, Kinnunen PK (1980) Serum and tissue distribution of benzol[α]pyrene from intravenously injected chylomicrons in rat in vivo. Cancer Lett 11: 113–119. doi: 10.1016/0304-3835(80)90101-9
[29]
Sureau F, Chinsky L, Duquesne M, Laigle A, Turpin PY, et al. (1990) Microspectrofluorimetric study of the kinetics of cellular uptake and metabolization of benzo(a)pyrene in human T 47D mammary tumor cells: evidence for cytochrome P1450 induction. Eur Biophys J 18: 301–307. doi: 10.1007/bf00188043
[30]
Verma N, Pink M, Petrat F, Rettenmeier AW, Schmitz-Spanke S (2012) Exposure of primary porcine urothelial cells to benzo(a)pyrene: in vitro uptake, intracellular concentration, and biological response. Arch Toxicol 86: 1861–1871. doi: 10.1007/s00204-012-0899-y
[31]
Kelman BJ, Springer DL (1982) Movements of benzo[α]pyrene across the hemochorial placenta of the guinea pig. Proc Soc Exp Biol Med 169: 58–62. doi: 10.3181/00379727-169-41307
[32]
Sarkadi B, Homolya L, Szakacs G, Varadi A (2006) Human multidrug resistance ABCB and ABCG transporters: participation in a chemoimmunity defense system. Physiol Rev 86: 1179–1236. doi: 10.1152/physrev.00037.2005
[33]
Sieuwerts AM, Klijn JG, Peters HA, Foekens JA (1995) The MTT tetrazolium salt assay scrutinized: how to use this assay reliably to measure metabolic activity of cell cultures in vitro for the assessment of growth characteristics, IC50-values and cell survival. Eur J Clin Chem Clin Biochem 33: 813–823. doi: 10.1515/cclm.1995.33.11.813
[34]
Bratosin D, Mitrofan L, Palii C, Estaquier J, Montreuil J (2005) Novel fluorescence assay using calcein-AM for the determination of human erythrocyte viability and aging. Cytometry A 66: 78–84. doi: 10.1002/cyto.a.20152
[35]
Mann CJ, Khallou J, Chevreuil O, Troussard AA, Guermani LM, et al. (1995) Mechanism of activation and functional significance of the lipolysis-stimulated receptor. Evidence for a role as chylomicron remnant receptor. Biochemistry 34: 10421–10431. doi: 10.1021/bi00033a014
[36]
Ahmad N, Girardet JM, Akbar S, Lanhers MC, Paris C, et al. (2012) Lactoferrin and its hydrolysate bind directly to the oleate-activated form of the lipolysis stimulated lipoprotein receptor. Febs J 279: 4361–4373. doi: 10.1111/febs.12026
[37]
Daniel TO, Schneider WJ, Goldstein JL, Brown MS (1983) Visualization of lipoprotein receptors by ligand blotting. J Biol Chem 258: 4606–4611.
[38]
Peiffer J, Cosnier F, Grova N, Nunge H, Salquèbre G, et al. (2013) Neurobehavioral toxicity of a repeated exposure (14 days) to the airborne polycyclic aromatic hydrocarbon fluorene in adult Wistar male rats. PLoS One 8: e71413. doi: 10.1371/journal.pone.0071413
[39]
Grova N, Salquèbre G, Schroeder H, Appenzeller BM (2011) Determination of PAHs and OH-PAHs in rat brain by gas chromatography tandem (triple quadrupole) mass spectrometry. Chem Res Toxicol 24: 1653–1667. doi: 10.1021/tx2003596
[40]
Yen FT, Masson M, Clossais-Besnard N, Andre P, Grosset JM, et al. (1999) Molecular cloning of a lipolysis-stimulated remnant receptor expressed in the liver. J Biol Chem 274: 13390–13398. doi: 10.1074/jbc.274.19.13390
[41]
Bihain BE, Yen FT (1992) Free fatty acids activate a high-affinity saturable pathway for degradation of low-density lipoproteins in fibroblasts from a subject homozygous for familial hypercholesterolemia. Biochemistry 31: 4628–4636. doi: 10.1021/bi00134a013
[42]
Bihain BE, Deckelbaum RJ, Yen FT, Gleeson AM, Carpentier YA, et al. (1989) Unesterified fatty acids inhibit the binding of low density lipoproteins to the human fibroblast low density lipoprotein receptor. J Biol Chem 264: 17316–17321.
[43]
Huang M, Blair IA, Penning TM (2013) Identification of stable benzo[α]pyrene-7,8-dione-DNA adducts in human lung cells. Chem Res Toxicol 26: 685–692. doi: 10.1021/tx300476m
[44]
Pruess-Schwartz D, Baird WM, Nikbakht A, Merrick BA, Selkirk JK (1986) Benzo(a)pyrene:DNA adduct formation in normal human mammary epithelial cell cultures and the human mammary carcinoma T47D cell line. Cancer Res 46: 2697–2702.
[45]
Wu K, Shan YJ, Zhao Y, Yu JW, Liu BH (2001) Inhibitory effects of RRR-alpha-tocopheryl succinate on benzo(a)pyrene (B(a)P)-induced forestomach carcinogenesis in female mice. World J Gastroenterol 7: 60–65.
[46]
Pleil JD, Stiegel MA, Sobus JR, Tabucchi S, Ghio AJ, et al. (2010) Cumulative exposure assessment for trace-level polycyclic aromatic hydrocarbons (PAHs) using human blood and plasma analysis. J Chromatogr B Analyt Technol Biomed Life Sci 878: 1753–1760. doi: 10.1016/j.jchromb.2010.04.035
[47]
Chien YC, Yeh CT (2012) Excretion kinetics of urinary 3-hydroxybenzo[α]pyrene following dietary exposure to benzo[α]pyrene in humans. Arch Toxicol 86: 45–53. doi: 10.1007/s00204-011-0727-9
[48]
Payan JP, Lafontaine M, Simon P, Marquet F, Champmargin-Gendre C, et al. (2009) 3-Hydroxybenzo(a)pyrene as a biomarker of dermal exposure to benzo(a)pyrene. Arch Toxicol 83: 873–883. doi: 10.1007/s00204-009-0440-0
[49]
Miura H, Tomoda H, Miura K, Takishima K, Omura S (1996) Lactacystin increases LDL receptor level on HepG2 cells. Biochem Biophys Res Commun 227: 684–687. doi: 10.1006/bbrc.1996.1569
[50]
Ogura M, Ayaori M, Terao Y, Hisada T, Iizuka M, et al. (2011) Proteasomal inhibition promotes ATP-binding cassette transporter A1 (ABCA1) and ABCG1 expression and cholesterol efflux from macrophages in vitro and in vivo. Arterioscler Thromb Vasc Biol 31: 1980–1987. doi: 10.1161/atvbaha.111.228478
[51]
Chen Y, Wang H, Yu L, Yu X, Qian YW, et al. (2011) Role of ubiquitination in PCSK9-mediated low-density lipoprotein receptor degradation. Biochem Biophys Res Commun 415: 515–518. doi: 10.1016/j.bbrc.2011.10.110
[52]
Wang Y, Huang Y, Hobbs HH, Cohen JC (2012) Molecular characterization of proprotein convertase subtilisin/kexin type 9-mediated degradation of the LDLR. J Lipid Res 53: 1932–1943. doi: 10.1194/jlr.m028563
[53]
Nakanishi Y, Pei XH, Takayama K, Bai F, Izumi M, et al. (2000) Polycyclic aromatic hydrocarbon carcinogens increase ubiquitination of p21 protein after the stabilization of p53 and the expression of p21. Am J Respir Cell Mol Biol 22: 747–754. doi: 10.1165/ajrcmb.22.6.3877
[54]
Polyakov LM, Chasovskikh MI, Panin LE (1996) Binding and transport of benzo[α]pyrene by blood plasma lipoproteins: the possible role of apolipoprotein B in this process. Bioconjug Chem 7: 396–400. doi: 10.1021/bc960005e
[55]
Brown MS, Goldstein JL (1997) The SREBP pathway: regulation of cholesterol metabolism by proteolysis of a membrane-bound transcription factor. Cell 89: 331–340. doi: 10.1016/s0092-8674(00)80213-5
[56]
de Faria E, Fong LG, Komaromy M, Cooper AD (1996) Relative roles of the LDL receptor, the LDL receptor-like protein, and hepatic lipase in chylomicron remnant removal by the liver. J Lipid Res 37: 197–209.
[57]
Ishibashi S, Perrey S, Chen Z, Osuga J, Shimada M, et al. (1996) Role of the low density lipoprotein (LDL) receptor pathway in the metabolism of chylomicron remnants. A quantitative study in knockout mice lacking the LDL receptor, apolipoprotein E, or both. J Biol Chem 271: 22422–22427. doi: 10.1074/jbc.271.37.22422
[58]
Ebert B, Seidel A, Lampen A (2005) Identification of BCRP as transporter of benzo[α]pyrene conjugates metabolically formed in Caco-2 cells and its induction by Ah-receptor agonists. Carcinogenesis 26: 1754–1763. doi: 10.1093/carcin/bgi139
[59]
Yang Y, Jiang Y, Wang Y, An W (2010) Suppression of ABCA1 by unsaturated fatty acids leads to lipid accumulation in HepG2 cells. Biochimie 92: 958–963. doi: 10.1016/j.biochi.2010.04.002
