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Sample records for cholesterol transport proteins

  1. How cholesterol interacts with proteins and lipids during its intracellular transport

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Solanko, Katarzyna

    2015-01-01

    as well as by non-vesicular sterol exchange between organelles. In this article, we will review recent progress in elucidating sterol-lipid and sterol-protein interactions contributing to proper sterol transport in living cells. We outline recent biophysical models of cholesterol distribution and dynamics...... for characterization of sterol-protein interactions and for monitoring intracellular sterol transport. Finally, we review recent work on the molecular mechanisms underlying lipoprotein-mediated cholesterol import into mammalian cells and describe the process of cellular cholesterol efflux. Overall, we emphasize how......Sterols, as cholesterol in mammalian cells and ergosterol in fungi, are indispensable molecules for proper functioning and nanoscale organization of the plasma membrane. Synthesis, uptake and efflux of cholesterol are regulated by a variety of protein-lipid and protein-protein interactions...

  2. Bilirubin Decreases Macrophage Cholesterol Efflux and ATP-Binding Cassette Transporter A1 Protein Expression.

    Science.gov (United States)

    Wang, Dongdong; Tosevska, Anela; Heiß, Elke H; Ladurner, Angela; Mölzer, Christine; Wallner, Marlies; Bulmer, Andrew; Wagner, Karl-Heinz; Dirsch, Verena M; Atanasov, Atanas G

    2017-04-28

    Mild but chronically elevated circulating unconjugated bilirubin is associated with reduced total and low-density lipoprotein cholesterol concentration, which is associated with reduced cardiovascular disease risk. We aimed to investigate whether unconjugated bilirubin influences macrophage cholesterol efflux, as a potential mechanism for the altered circulating lipoprotein concentrations observed in hyperbilirubinemic individuals. Cholesterol efflux from THP-1 macrophages was assessed using plasma obtained from normo- and hyperbilirubinemic (Gilbert syndrome) humans (n=60 per group) or (heterozygote/homozygote Gunn) rats (n=20 per group) as an acceptor. Hyperbilirubinemic plasma from patients with Gilbert syndrome and Gunn rats induced significantly reduced cholesterol efflux compared with normobilirubinemic plasma. Unconjugated bilirubin (3-17.1 μmol/L) exogenously added to plasma- or apolipoprotein A1-supplemented media also decreased macrophage cholesterol efflux in a concentration- and time-dependent manner. We also showed reduced protein expression of the ATP-binding cassette transporter A1 (ABCA1), a transmembrane cholesterol transporter involved in apolipoprotein A1-mediated cholesterol efflux, in THP-1 macrophages treated with unconjugated bilirubin and in peripheral blood mononuclear cells obtained from hyperbilirubinemic individuals. Furthermore, we demonstrated that bilirubin accelerates the degradation rate of the ABCA1 protein in THP-1 macrophages. Cholesterol efflux from THP-1 macrophages is decreased in the presence of plasma obtained from humans and rats with mild hyperbilirubinemia. A direct effect of unconjugated bilirubin on cholesterol efflux was demonstrated and is associated with decreased ABCA1 protein expression. These data improve our knowledge concerning bilirubin's impact on cholesterol transport and represent an important advancement in our understanding of bilirubin's role in cardiovascular disease. © 2017 The Authors. Published on

  3. The Endoplasmic Reticulum Coat Protein II Transport Machinery Coordinates Cellular Lipid Secretion and Cholesterol Biosynthesis*

    Science.gov (United States)

    Fryer, Lee G. D.; Jones, Bethan; Duncan, Emma J.; Hutchison, Claire E.; Ozkan, Tozen; Williams, Paul A.; Alder, Olivia; Nieuwdorp, Max; Townley, Anna K.; Mensenkamp, Arjen R.; Stephens, David J.; Dallinga-Thie, Geesje M.; Shoulders, Carol C.

    2014-01-01

    Triglycerides and cholesterol are essential for life in most organisms. Triglycerides serve as the principal energy storage depot and, where vascular systems exist, as a means of energy transport. Cholesterol is essential for the functional integrity of all cellular membrane systems. The endoplasmic reticulum is the site of secretory lipoprotein production and de novo cholesterol synthesis, yet little is known about how these activities are coordinated with each other or with the activity of the COPII machinery, which transports endoplasmic reticulum cargo to the Golgi. The Sar1B component of this machinery is mutated in chylomicron retention disorder, indicating that this Sar1 isoform secures delivery of dietary lipids into the circulation. However, it is not known why some patients with chylomicron retention disorder develop hepatic steatosis, despite impaired intestinal fat malabsorption, and why very severe hypocholesterolemia develops in this condition. Here, we show that Sar1B also promotes hepatic apolipoprotein (apo) B lipoprotein secretion and that this promoting activity is coordinated with the processes regulating apoB expression and the transfer of triglycerides/cholesterol moieties onto this large lipid transport protein. We also show that although Sar1A antagonizes the lipoprotein secretion-promoting activity of Sar1B, both isoforms modulate the expression of genes encoding cholesterol biosynthetic enzymes and the synthesis of cholesterol de novo. These results not only establish that Sar1B promotes the secretion of hepatic lipids but also adds regulation of cholesterol synthesis to Sar1B's repertoire of transport functions. PMID:24338480

  4. Overexpression and deletion of phospholipid transfer protein reduce HDL mass and cholesterol efflux capacity but not macrophage reverse cholesterol transport[S

    Science.gov (United States)

    Kuwano, Takashi; Bi, Xin; Cipollari, Eleonora; Yasuda, Tomoyuki; Lagor, William R.; Szapary, Hannah J.; Tohyama, Junichiro; Millar, John S.; Billheimer, Jeffrey T.; Lyssenko, Nicholas N.; Rader, Daniel J.

    2017-01-01

    Phospholipid transfer protein (PLTP) may affect macrophage reverse cholesterol transport (mRCT) through its role in the metabolism of HDL. Ex vivo cholesterol efflux capacity and in vivo mRCT were assessed in PLTP deletion and PLTP overexpression mice. PLTP deletion mice had reduced HDL mass and cholesterol efflux capacity, but unchanged in vivo mRCT. To directly compare the effects of PLTP overexpression and deletion on mRCT, human PLTP was overexpressed in the liver of wild-type animals using an adeno-associated viral (AAV) vector, and control and PLTP deletion animals were injected with AAV-null. PLTP overexpression and deletion reduced plasma HDL mass and cholesterol efflux capacity. Both substantially decreased ABCA1-independent cholesterol efflux, whereas ABCA1-dependent cholesterol efflux remained the same or increased, even though preβ HDL levels were lower. Neither PLTP overexpression nor deletion affected excretion of macrophage-derived radiocholesterol in the in vivo mRCT assay. The ex vivo and in vivo assays were modified to gauge the rate of cholesterol efflux from macrophages to plasma. PLTP activity did not affect this metric. Thus, deviations in PLTP activity from the wild-type level reduce HDL mass and ex vivo cholesterol efflux capacity, but not the rate of macrophage cholesterol efflux to plasma or in vivo mRCT. PMID:28137768

  5. The endoplasmic reticulum coat protein II transport machinery coordinates cellular lipid secretion and cholesterol biosynthesis

    NARCIS (Netherlands)

    Fryer, Lee G. D.; Jones, Bethan; Duncan, Emma J.; Hutchison, Claire E.; Ozkan, Tozen; Williams, Paul A.; Alder, Olivia; Nieuwdorp, Max; Townley, Anna K.; Mensenkamp, Arjen R.; Stephens, David J.; Dallinga-Thie, Geesje M.; Shoulders, Carol C.

    2014-01-01

    Triglycerides and cholesterol are essential for life in most organisms. Triglycerides serve as the principal energy storage depot and, where vascular systems exist, as a means of energy transport. Cholesterol is essential for the functional integrity of all cellular membrane systems. The endoplasmic

  6. Pitavastatin Differentially Modulates MicroRNA-Associated Cholesterol Transport Proteins in Macrophages.

    Directory of Open Access Journals (Sweden)

    Haijun Zhang

    Full Text Available There is emerging evidence identifying microRNAs (miRNAs as mediators of statin-induced cholesterol efflux, notably through the ATP-binding cassette transporter A1 (ABCA1 in macrophages. The objective of this study was to assess the impact of an HMG-CoA reductase inhibitor, pitavastatin, on macrophage miRNAs in the presence and absence of oxidized-LDL, a hallmark of a pro-atherogenic milieu. Treatment of human THP-1 cells with pitavastatin prevented the oxLDL-mediated suppression of miR-33a, -33b and -758 mRNA in these cells, an effect which was not uniquely attributable to induction of SREBP2. Induction of ABCA1 mRNA and protein by oxLDL was inhibited (30% by pitavastatin, while oxLDL or pitavastatin alone significantly induced and repressed ABCA1 expression, respectively. These findings are consistent with previous reports in macrophages. miRNA profiling was also performed using a miRNA array. We identified specific miRNAs which were up-regulated (122 and down-regulated (107 in THP-1 cells treated with oxLDL plus pitavastatin versus oxLDL alone, indicating distinct regulatory networks in these cells. Moreover, several of the differentially expressed miRNAs identified are functionally associated with cholesterol trafficking (six miRNAs in cells treated with oxLDL versus oxLDL plus pitavastatin. Our findings indicate that pitavastatin can differentially modulate miRNA in the presence of oxLDL; and, our results provide evidence that the net effect on cholesterol homeostasis is mediated by a network of miRNAs.

  7. Maternal-fetal cholesterol transport in the second half of mouse pregnancy does not involve LDL receptor-related protein 2.

    Science.gov (United States)

    Zwier, M V; Baardman, M E; van Dijk, T H; Jurdzinski, A; Wisse, L J; Bloks, V W; Berger, R M F; DeRuiter, M C; Groen, A K; Plösch, T

    2017-08-01

    LDL receptor-related protein type 2 (LRP2) is highly expressed on both yolk sac and placenta. Mutations in the corresponding gene are associated with severe birth defects in humans, known as Donnai-Barrow syndrome. We here characterized the contribution of LRP2 and maternal plasma cholesterol availability to maternal-fetal cholesterol transport and fetal cholesterol levels in utero in mice. Lrp2 +/- mice were mated heterozygously to yield fetuses of all three genotypes. Half of the dams received a 0.5% probucol-enriched diet during gestation to decrease maternal HDL cholesterol. At E13.5, the dams received an injection of D7-labelled cholesterol and were provided with 1- 13 C acetate-supplemented drinking water. At E16.5, fetal tissues were collected and maternal cholesterol transport and fetal synthesis quantified by isotope enrichments in fetal tissues by GC-MS. The Lrp2 genotype did not influence maternal-fetal cholesterol transport and fetal cholesterol. However, lowering of maternal plasma cholesterol levels by probucol significantly reduced maternal-fetal cholesterol transport. In the fetal liver, this was associated with increased cholesterol synthesis rates. No indications were found for an interaction between the Lrp2 genotype and maternal probucol treatment. Maternal-fetal cholesterol transport and endogenous fetal cholesterol synthesis depend on maternal cholesterol concentrations but do not involve LRP2 in the second half of murine pregnancy. Our results suggest that the mouse fetus can compensate for decreased maternal cholesterol levels. It remains a relevant question how the delicate system of cholesterol transport and synthesis is regulated in the human fetus and placenta. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  8. Characterization of placental cholesterol transport

    DEFF Research Database (Denmark)

    Lindegaard, Marie L; Wassif, Christopher A; Vaisman, Boris

    2008-01-01

    Patients with Smith-Lemli-Opitz syndrome (SLOS) are born with multiple congenital abnormalities. Postnatal cholesterol supplementation is provided; however, it cannot correct developmental malformations due to in utero cholesterol deficit. Increased transport of cholesterol from maternal to fetal...... circulation might attenuate congenital malformations. The cholesterol transporters Abca1, Abcg1, and Sr-b1 are present in placenta; however, their potential role in placental transport remains undetermined. In mice, expression analyses showed that Abca1 and Abcg1 transcripts increased 2-3-fold between...... embryonic days 13.5 and 18.5 in placental tissue; whereas, Sr-b1 expression decreased. To examine the functional role of Abca1, Abcg1 and Sr-b1 we measured the maternal-fetal transfer of (14)C-cholesterol in corresponding mutant embryos. Disruption of either Abca1 or Sr-b1 decreased cholesterol transfer...

  9. Relevance of hereditary defects in lipid transport proteins for the pathogenesis of cholesterol gallstone disease

    NARCIS (Netherlands)

    vanBerge-Henegouwen, G. P.; Venneman, N. G.; Portincasa, P.; Kosters, A.; van Erpecum, K. J.; Groen, A. K.

    2004-01-01

    In the formation of cholesterol gallstones, cholesterol hypersecretion into bile causing cholesterol supersaturation and crystallization appears to be the primary factor, with disturbed gallbladder and intestinal motility as secondary factors. Although intestinal uptake mechanisms have not yet been

  10. Intestinal cholesterol transport: Measuring cholesterol absorption and its reverse

    NARCIS (Netherlands)

    Jakulj, L.

    2013-01-01

    Intestinal cholesterol transport might serve as an attractive future target for cardiovascular disease reduction, provided that underlying molecular mechanisms are more extensively elucidated, combined with improved techniques to measure changes in cholesterol fluxes and their possible

  11. Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1*

    Science.gov (United States)

    Hsieh, Victar; Kim, Mi-Jurng; Gelissen, Ingrid C.; Brown, Andrew J.; Sandoval, Cecilia; Hallab, Jeannette C.; Kockx, Maaike; Traini, Mathew; Jessup, Wendy; Kritharides, Leonard

    2014-01-01

    The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes. PMID:24500716

  12. Maternal-fetal cholesterol transport in the second half ofmouse pregnancy does not involve LDL receptor-related protein 2

    NARCIS (Netherlands)

    Zwier, Mathijs V; Baardman, Maria E; van Dijk, Theo H; Jurdzinski, Angelika; Wisse, Lambertus J; Bloks, Vincent W; Berger, Rolf M F; DeRuiter, Marco C; Groen, Albert K; Plösch, Torsten

    AimLDL receptor-related protein type 2 (LRP2) is highly expressed on both yolk sac and placenta. Mutations in the corresponding gene are associated with severe birth defects in humans, known as Donnai-Barrow syndrome. We here characterized the contribution of LRP2 and maternal plasma cholesterol

  13. Scavenger receptor class B member 1 protein: hepatic regulation and its effects on lipids, reverse cholesterol transport, and atherosclerosis

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    Kent AP

    2011-04-01

    Full Text Available Anthony P Kent, Ioannis M StylianouDepartment of Medicine and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USAAbstract: Scavenger receptor class B member 1 (SR-BI, also known as SCARB1 is the primary receptor for the selective uptake of cholesterol from high-density lipoprotein (HDL. SR-BI is present in several key tissues; however, its presence and function in the liver is deemed the most relevant for protection against atherosclerosis. Cholesterol is transferred from HDL via SR-BI to the liver, which ultimately results in the excretion of cholesterol via bile and feces in what is known as the reverse cholesterol transport pathway. Much of our knowledge of SR-BI hepatic function and regulation is derived from mouse models and in vitro characterization. Multiple independent regulatory mechanisms of SR-BI have been discovered that operate at the transcriptional and post-transcriptional levels. In this review we summarize the critical discoveries relating to hepatic SR-BI cholesterol metabolism, atherosclerosis, and regulation of SR-BI, as well as alternative functions that may indirectly affect atherosclerosis.Keywords: SR-BI, SCARB1, lipids, atherosclerosis, CAD, mouse models

  14. Intracellular transport of cholesterol in mammalian cells

    International Nuclear Information System (INIS)

    Brasaemle, D.L.

    1989-01-01

    The erythrocyte was selected as a simple cell for the study of transbilayer movement of cholesterol. Cholesterol oxidase was used to measure the distribution of [ 3 H]cholesterol across the erythrocyte membrane. Cholesterol oxidase was also used to estimate the rate of transport of low density lipoprotein (LDL) cholesterol to the plasma membrane of cultured Chinese hamster ovary (CHO) fibroblasts; the half-time of this process was 42 minutes. The rate of transport of LDL cholesterol to the plasma membrane was confirmed by a second procedure using amphotericin B. Amphotericin B was also used to estimate the rate of transport of endogenously synthesized cholesterol to the plasma membrane of CHO cells. New methodology was developed including improvements of the previously published cholesterol oxidase assay for plasma membrane cholesterol. A new method for detecting transport of cholesterol to the plasma membrane in cultured cells was developed using amphotericin B. Preliminary studies investigated the use of fluorescent polyenes, pimaricin and etruscomycin, as probes for plasma membrane cholesterol in transport studies. Finally, a modification of a previously published cell staining protocol yielded a simple, quantitative assay for cell growth

  15. Upregulating reverse cholesterol transport with cholesteryl ester transfer protein inhibition requires combination with the LDL-lowering drug berberine in dyslipidemic hamsters.

    Science.gov (United States)

    Briand, François; Thieblemont, Quentin; Muzotte, Elodie; Sulpice, Thierry

    2013-01-01

    This study aimed to investigate whether cholesteryl ester transfer protein inhibition promotes in vivo reverse cholesterol transport in dyslipidemic hamsters. In vivo reverse cholesterol transport was measured after an intravenous injection of (3)H-cholesteryl-oleate-labeled/oxidized low density lipoprotein particles ((3)H-oxLDL), which are rapidly cleared from plasma by liver-resident macrophages for further (3)H-tracer egress in plasma, high density lipoprotein (HDL), liver, and feces. A first set of hamsters made dyslipidemic with a high-fat and high-fructose diet was treated with vehicle or torcetrapib 30 mg/kg (TOR) over 2 weeks. Compared with vehicle, TOR increased apolipoprotein E-rich HDL levels and significantly increased (3)H-tracer appearance in HDL by 30% over 72 hours after (3)H-oxLDL injection. However, TOR did not change (3)H-tracer recovery in liver and feces, suggesting that uptake and excretion of cholesterol deriving from apolipoprotein E-rich HDL is not stimulated. As apoE is a potent ligand for the LDL receptor, we next evaluated the effects of TOR in combination with the LDL-lowering drug berberine, which upregulates LDL receptor expression in dyslipidemic hamsters. Compared with TOR alone, treatment with TOR+berberine 150 mg/kg resulted in lower apolipoprotein E-rich HDL levels. After (3)H-oxLDL injection, TOR+berberine significantly increased (3)H-tracer appearance in fecal cholesterol by 109%. Our data suggest that cholesteryl ester transfer protein inhibition alone does not stimulate reverse cholesterol transport in dyslipidemic hamsters and that additional effects mediated by the LDL-lowering drug berberine are required to upregulate this process.

  16. Intracellular cholesterol-binding proteins enhance HDL-mediated cholesterol uptake in cultured primary mouse hepatocytes.

    Science.gov (United States)

    Storey, Stephen M; McIntosh, Avery L; Huang, Huan; Landrock, Kerstin K; Martin, Gregory G; Landrock, Danilo; Payne, H Ross; Atshaves, Barbara P; Kier, Ann B; Schroeder, Friedhelm

    2012-04-15

    A major gap in our knowledge of rapid hepatic HDL cholesterol clearance is the role of key intracellular factors that influence this process. Although the reverse cholesterol transport pathway targets HDL to the liver for net elimination of free cholesterol from the body, molecular details governing cholesterol uptake into hepatocytes are not completely understood. Therefore, the effects of sterol carrier protein (SCP)-2 and liver fatty acid-binding protein (L-FABP), high-affinity cholesterol-binding proteins present in hepatocyte cytosol, on HDL-mediated free cholesterol uptake were examined using gene-targeted mouse models, cultured primary hepatocytes, and 22-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-amino]-23,24-bisnor-5-cholen-3β-ol (NBD-cholesterol). While SCP-2 overexpression enhanced NBD-cholesterol uptake, counterintuitively, SCP-2/SCP-x gene ablation also 1) enhanced the rapid molecular phase of free sterol uptake detectable in rate and maximal uptake of HDL free cholesterol and 2) differentially enhanced free cholesterol uptake mediated by the HDL3, rather than the HDL2, subfraction. The increased HDL free cholesterol uptake was not due to increased expression or distribution of the HDL receptor [scavenger receptor B1 (SRB1)], proteins regulating SRB1 [postsynaptic density protein (PSD-95)/Drosophila disk large tumor suppressor (dlg)/tight junction protein (ZO1) and 17-kDa membrane-associated protein], or other intracellular cholesterol trafficking proteins (steroidogenic acute response protein D, Niemann Pick C, and oxysterol-binding protein-related proteins). However, expression of L-FABP, the single most prevalent hepatic cytosolic protein that binds cholesterol, was upregulated twofold in SCP-2/SCP-x null hepatocytes. Double-immunogold electron microscopy detected L-FABP sufficiently close to SRB1 for direct interaction, similar to SCP-2. These data suggest a role for L-FABP in HDL cholesterol uptake, a finding confirmed with SCP-2/SCP-x/L-FABP null

  17. The ABC of cholesterol transport

    NARCIS (Netherlands)

    Plösch, Torsten

    2004-01-01

    Cholesterol fulfills an indispensable role in mammalian physiology. It is an important constituent of all cell membranes. Furthermore, it is the precursor of steroid hormones, which regulate a variety of physiological functions, and of bile salts, which are necessary for the generation of bile flow

  18. Cholesterol-induced protein sorting: an analysis of energetic feasibility

    DEFF Research Database (Denmark)

    Lundbaek, J A; Andersen, O S; Werge, T

    2003-01-01

    thickness. In this model, Golgi proteins with short TMDs would be excluded from cholesterol-enriched domains (lipid rafts) that are incorporated into transport vesicles destined for the plasma membrane. Although attractive, this model remains unproven. We therefore evaluated the energetic feasibility...

  19. Cholesterol Transport Revisited : A New Turbo Mechanism to Drive Cholesterol Excretion

    NARCIS (Netherlands)

    de Boer, Jan Freark; Kuipers, Folkert; Groen, Albert K.

    A fine-tuned balance between cholesterol uptake and excretion by the body is pivotal to maintain health and to remain free from the deleterious consequences of cholesterol accumulation such as cardiovascular disease. The pathways involved in intracellular and extracellular cholesterol transport are

  20. The Role of Macrophage Lipophagy in Reverse Cholesterol Transport

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    Se-Jin Jeong

    2017-03-01

    Full Text Available Macrophage cholesterol efflux is a central step in reverse cholesterol transport, which helps to maintain cholesterol homeostasis and to reduce atherosclerosis. Lipophagy has recently been identified as a new step in cholesterol ester hydrolysis that regulates cholesterol efflux, since it mobilizes cholesterol from lipid droplets of macrophages via autophagy and lysosomes. In this review, we briefly discuss recent advances regarding the mechanisms of the cholesterol efflux pathway in macrophage foam cells, and present lipophagy as a therapeutic target in the treatment of atherosclerosis.

  1. Protein complexes and cholesterol in the control of late endosomal dynamicsCholesterol and multi-protein complexes in the control of late endosomal dynamics

    NARCIS (Netherlands)

    Kant, Rik Henricus Nicolaas van der

    2013-01-01

    Late endosomal transport is disrupted in several diseases such as Niemann-Pick type C, ARC syndrome and Alzheimer’s disease. This thesis describes the regulation of late endosomal dynamics by cholesterol and multi-protein complexes. We find that cholesterol acts as a cellular tomtom that steers the

  2. Regulation of biliary cholesterol secretion and reverse cholesterol transport

    NARCIS (Netherlands)

    Dikkers, Arne

    2016-01-01

    According to the World Health Organization the number one cause of death throughout the world is cardiovascular disease. Therefore, there is an urgent need for new therapeutic strategies to prevent and treat cardiovascular disease. One possible way is to target the HDL-driven reverse cholesterol

  3. Alcohol consumption stimulates early stemps in reverse cholesterol transport

    NARCIS (Netherlands)

    Gaag, van der M.S.; Tol, van A.; Vermunt, S.H.F.; Scheek, L.M.; Schaafsma, G.; Hendriks, H.F.J.

    2001-01-01

    Alcohol consumption is associated with increased HDL cholesterol levels, which may indicate stimulated reverse cholesterol transport. The mechanism is, however, not known. The aim of this study was to evaluate the effects of alcohol consumption on the first two steps of the reverse cholesterol

  4. Alcohol consumption stimulates early steps in reverse cholesterol transport

    NARCIS (Netherlands)

    Gaag, M.S. van der; Tol, A. van; Vermunt, S.H.F.; Scheek, L.M.; Schaafsma, G.; Hendriks, H.F.J.

    2001-01-01

    Alcohol consumption is associated with increased HDL cholesterol levels, which may indicate stimulated reverse cholesterol transport. The mechanism is, however, not known. The aim of this study was to evaluate the effects of alcohol consumption on the first two steps of the reverse cholesterol

  5. The GARP Complex Is Involved in Intracellular Cholesterol Transport via Targeting NPC2 to Lysosomes.

    Science.gov (United States)

    Wei, Jian; Zhang, Ying-Yu; Luo, Jie; Wang, Ju-Qiong; Zhou, Yu-Xia; Miao, Hong-Hua; Shi, Xiong-Jie; Qu, Yu-Xiu; Xu, Jie; Li, Bo-Liang; Song, Bao-Liang

    2017-06-27

    Proper intracellular cholesterol trafficking is critical for cellular function. Two lysosome-resident proteins, NPC1 and NPC2, mediate the egress of low-density lipoprotein-derived cholesterol from lysosomes. However, other proteins involved in this process remain largely unknown. Through amphotericin B-based selection, we isolated two cholesterol transport-defective cell lines. Subsequent whole-transcriptome-sequencing analysis revealed two cell lines bearing the same mutation in the vacuolar protein sorting 53 (Vps53) gene. Depletion of VPS53 or other subunits of the Golgi-associated retrograde protein (GARP) complex impaired NPC2 sorting to lysosomes and caused cholesterol accumulation. GARP deficiency blocked the retrieval of the cation-independent mannose 6-phosphate receptor (CI-MPR) to the trans-Golgi network. Further, Vps54 mutant mice displayed reduced cellular NPC2 protein levels and increased cholesterol accumulation, underscoring the physiological role of the GARP complex in cholesterol transport. We conclude that the GARP complex contributes to intracellular cholesterol transport by targeting NPC2 to lysosomes in a CI-MPR-dependent manner. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  6. 3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaochun; Lu, Feiran; Trinh, Michael N.; Schmiege, Philip; Seemann, Joachim; Wang, Jiawei; Blobel, Günter

    2017-08-07

    Niemann–Pick C1 (NPC1) and NPC2 proteins are indispensable for the export of LDL-derived cholesterol from late endosomes. Mutations in these proteins result in Niemann–Pick type C disease, a lysosomal storage disease. Despite recent reports of the NPC1 structure depicting its overall architecture, the function of its C-terminal luminal domain (CTD) remains poorly understood even though 45% of NPC disease-causing mutations are in this domain. Here, we report a crystal structure at 3.3 Å resolution of NPC1* (residues 314–1,278), which—in contrast to previous lower resolution structures—features the entire CTD well resolved. Notably, all eight cysteines of the CTD form four disulfide bonds, one of which (C909–C914) enforces a specific loop that in turn mediates an interaction with a loop of the N-terminal domain (NTD). Importantly, this loop and its interaction with the NTD were not observed in any previous structures due to the lower resolution. Our mutagenesis experiments highlight the physiological relevance of the CTD–NTD interaction, which might function to keep the NTD in the proper orientation for receiving cholesterol from NPC2. Additionally, this structure allows us to more precisely map all of the disease-causing mutations, allowing future molecular insights into the pathogenesis of NPC disease.

  7. Nuclear receptors in control of cholesterol transport

    NARCIS (Netherlands)

    van der Veen, Jelske Nynke

    2007-01-01

    Cholesterol is een structurele component van celmembranen en een grondstof voor de aanmaak van steroïde hormonen en galzouten en vervult dus een aantal essentiële fysiologische functies. Een goede balans van cholesterol opname, synthese, afbraak en uitscheiding is noodzakelijk, omdat verhoogde

  8. Oxysterol-Binding Protein-Related Protein 1L Regulates Cholesterol Egress from the Endo-Lysosomal System

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    Kexin Zhao

    2017-05-01

    Full Text Available Lipoprotein cholesterol is delivered to the limiting membrane of late endosomes/lysosomes (LELs by Niemann-Pick C1 (NPC1. However, the mechanism of cholesterol transport from LELs to the endoplasmic reticulum (ER is poorly characterized. We report that oxysterol-binding protein-related protein 1L (ORP1L is necessary for this stage of cholesterol export. CRISPR-mediated knockout of ORP1L in HeLa and HEK293 cells reduced esterification of cholesterol to the level in NPC1 knockout cells, and it increased the expression of sterol-regulated genes and de novo cholesterol synthesis, indicative of a block in cholesterol transport to the ER. In the absence of this transport pathway, cholesterol-enriched LELs accumulated in the Golgi/perinuclear region. Cholesterol delivery to the ER required the sterol-, phosphatidylinositol 4-phosphate-, and vesicle-associated membrane protein-associated protein (VAP-binding activities of ORP1L, as well as NPC1 expression. These results suggest that ORP1L-dependent membrane contacts between LELs and the ER coordinate cholesterol transfer with the retrograde movement of endo-lysosomal vesicles.

  9. The structure of a cholesterol-trapping protein

    Science.gov (United States)

    cholesterol-trapping protein Contact: Dan Krotz, dakrotz@lbl.gov Berkeley Lab Science Beat Lab website index Institute researchers determined the three-dimensional structure of a protein that controls cholesterol level in the bloodstream. Knowing the structure of the protein, a cellular receptor that ensnares

  10. Lymphatic vasculature mediates macrophage reverse cholesterol transport in mice

    NARCIS (Netherlands)

    Martel, Catherine; Li, Wenjun; Fulp, Brian; Platt, Andrew M.; Gautier, Emmanuel L.; Westerterp, Marit; Bittman, Robert; Tall, Alan R.; Chen, Shu-Hsia; Thomas, Michael J.; Kreisel, Daniel; Swartz, Melody A.; Sorci-Thomas, Mary G.; Randolph, Gwendalyn J.

    2013-01-01

    Reverse cholesterol transport (RCT) refers to the mobilization of cholesterol on HDL particles (HDL-C) from extravascular tissues to plasma, ultimately for fecal excretion. Little is known about how HDL-C leaves peripheral tissues to reach plasma. We first used 2 models of disrupted lymphatic

  11. Modulation of cholesterol transport by maternal hypercholesterolemia in human full-term placenta.

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    Ran Zhang

    Full Text Available The significance of maternal cholesterol transporting to the fetus under normal as well as pathological circumstances is less understood. The objective of this study was to observe the effects of maternal hypercholesterolemia on placental cholesterol transportation. Human full-time placenta, maternal and venous cord blood were sampled at delivery from the pregnant women with serum total cholesterol (TC concentrations at third trimester higher than 7.25 mM (n = 19 and the pregnant women with normal TC concentrations (n = 19. Serum lipids and expression of genes related to cholesterol transportation were measured by western blot or real-time PCR. The results indicated that serum TC, high density lipoprotein cholesterol (HDL-C, and low density lipoprotein cholesterol (LDL-C levels were significantly increased, in pregnancies, but decreased in cord blood in hypercholesterolemic group compared to the matched control group. All the subjects were no-drinking, non-smoker, and gestational disease free. The mRNA expression of lipoprotein receptors, including LDLR and VLDLR were significantly increased, while the protein expression of PCSK9 was significantly increased in hypercholesterolemic placenta. In conclusion, maternal hypercholesterolemia might decrease the transportation of cholesterol from mother to fetus because of the high levels of PCSK9 protein expression.

  12. Lymphatic vasculature mediates macrophage reverse cholesterol transport in mice.

    Science.gov (United States)

    Martel, Catherine; Li, Wenjun; Fulp, Brian; Platt, Andrew M; Gautier, Emmanuel L; Westerterp, Marit; Bittman, Robert; Tall, Alan R; Chen, Shu-Hsia; Thomas, Michael J; Kreisel, Daniel; Swartz, Melody A; Sorci-Thomas, Mary G; Randolph, Gwendalyn J

    2013-04-01

    Reverse cholesterol transport (RCT) refers to the mobilization of cholesterol on HDL particles (HDL-C) from extravascular tissues to plasma, ultimately for fecal excretion. Little is known about how HDL-C leaves peripheral tissues to reach plasma. We first used 2 models of disrupted lymphatic drainage from skin--1 surgical and the other genetic--to quantitatively track RCT following injection of [3H]-cholesterol-loaded macrophages upstream of blocked or absent lymphatic vessels. Macrophage RCT was markedly impaired in both models, even at sites with a leaky vasculature. Inhibited RCT was downstream of cholesterol efflux from macrophages, since macrophage efflux of a fluorescent cholesterol analog (BODIPY-cholesterol) was not altered by impaired lymphatic drainage. We next addressed whether RCT was mediated by lymphatic vessels from the aortic wall by loading the aortae of donor atherosclerotic Apoe-deficient mice with [2H]6-labeled cholesterol and surgically transplanting these aortae into recipient Apoe-deficient mice that were treated with anti-VEGFR3 antibody to block lymphatic regrowth or with control antibody to allow such regrowth. [2H]-Cholesterol was retained in aortae of anti-VEGFR3-treated mice. Thus, the lymphatic vessel route is critical for RCT from multiple tissues, including the aortic wall. These results suggest that supporting lymphatic transport function may facilitate cholesterol clearance in therapies aimed at reversing atherosclerosis.

  13. Heat shock protein 27-derived atheroprotection involves reverse cholesterol transport that is dependent on GM-CSF to maintain ABCA1 and ABCG1 expression in ApoE-/- mice.

    Science.gov (United States)

    Pulakazhi Venu, Vivek Krishna; Adijiang, Ayinuer; Seibert, Tara; Chen, Yong-Xiang; Shi, Chunhua; Batulan, Zarah; O'Brien, Edward R

    2017-06-01

    Recently, we demonstrated that heat shock protein (HSP)-27 is protective against the development of experimental atherosclerosis, reducing plaque cholesterol content by more than 30%. Moreover, elevated HSP-27 levels are predictive of relative freedom from clinical cardiovascular events. HSP-27 signaling occurs via the activation of NF-κB, which induces a marked up-regulation in expression of granulocyte-monocyte colony-stimulating factor (GM-CSF), a cytokine that is known to alter ABC transporters involved in reverse cholesterol transport (RCT). Therefore, we hypothesized that HSP-27-derived GM-CSF has a potent role in impeding plaque formation by promoting macrophage RCT and sought to better characterize this pathway. Treatment of THP-1 cells, RAW-Blue cells, and primary macrophages with recombinant HSP-27 resulted in NF-κB activation via TLR-4 and was inhibited by various pharmacologic blockers of this pathway. Moreover, HSP-27-induced upregulation of GM-CSF expression was dependent on TLR-4 signaling. Recombinant (r)HSP-27 treatment of ApoE -/- female (but not male) mice for 4 wk yielded reductions in plaque area and cholesterol clefts of 33 and 47%, respectively, with no effect on GM-CSF -/- ApoE -/- mice. With 12 wk of rHSP-27 treatment, both female and male mice showed reductions in plaque burden (55 and 42%, respectively) and a 60% reduction in necrotic core area but no treatment effect in GM-CSF -/- ApoE -/- mice. In vitro functional studies revealed that HSP-27 enhanced the expression of ABCA1 and ABCG1, as well as facilitated cholesterol efflux in vitro by ∼10%. These novel findings establish a paradigm for HSP-27-mediated RCT and set the stage for the development of HSP-27 atheroprotective therapeutics.-Pulakazhi Venu, V. K., Adijiang, A., Seibert, T., Chen, Y.-X., Shi, C., Batulan, Z., O'Brien, E. R. Heat shock protein 27-derived atheroprotection involves reverse cholesterol transport that is dependent on GM-CSF to maintain ABCA1 and ABCG1

  14. Macrophage mitochondrial damage from StAR transport of 7-hydroperoxycholesterol: implications for oxidative stress-impaired reverse cholesterol transport.

    Science.gov (United States)

    Korytowski, Witold; Wawak, Katarzyna; Pabisz, Pawel; Schmitt, Jared C; Girotti, Albert W

    2014-01-03

    StAR family proteins in vascular macrophages participate in reverse cholesterol transport (RCT). We hypothesize that under pathophysiological oxidative stress, StARs will transport not only cholesterol to macrophage mitochondria, but also pro-oxidant cholesterol hydroperoxides (7-OOHs), thereby impairing early-stage RCT. Upon stimulation with dibutyryl-cAMP, RAW264.7 macrophages exhibited a strong time-dependent induction of mitochondrial StarD1 and plasma membrane ABCA1, which exports cholesterol. 7α-OOH uptake by stimulated RAW cell mitochondria (like cholesterol uptake) was strongly reduced by StarD1 knockdown, consistent with StarD1 involvement. Upon uptake by mitochondria, 7α-OOH (but not redox-inactive 7α-OH) triggered lipid peroxidation and membrane depolarization while reducing ABCA1 upregulation. These findings provide strong initial support for our hypothesis. Copyright © 2013. Published by Elsevier B.V.

  15. The hedgehog receptor patched is involved in cholesterol transport.

    Directory of Open Access Journals (Sweden)

    Michel Bidet

    Full Text Available Sonic hedgehog (Shh signaling plays a crucial role in growth and patterning during embryonic development, and also in stem cell maintenance and tissue regeneration in adults. Aberrant Shh pathway activation is involved in the development of many tumors, and one of the most affected Shh signaling steps found in these tumors is the regulation of the signaling receptor Smoothened by the Shh receptor Patched. In the present work, we investigated Patched activity and the mechanism by which Patched inhibits Smoothened.Using the well-known Shh-responding cell line of mouse fibroblasts NIH 3T3, we first observed that enhancement of the intracellular cholesterol concentration induces Smoothened enrichment in the plasma membrane, which is a crucial step for the signaling activation. We found that binding of Shh protein to its receptor Patched, which involves Patched internalization, increases the intracellular concentration of cholesterol and decreases the efflux of a fluorescent cholesterol derivative (BODIPY-cholesterol from these cells. Treatment of fibroblasts with cyclopamine, an antagonist of Shh signaling, inhibits Patched expression and reduces BODIPY-cholesterol efflux, while treatment with the Shh pathway agonist SAG enhances Patched protein expression and BODIPY-cholesterol efflux. We also show that over-expression of human Patched in the yeast S. cerevisiae results in a significant boost of BODIPY-cholesterol efflux. Furthermore, we demonstrate that purified Patched binds to cholesterol, and that the interaction of Shh with Patched inhibits the binding of Patched to cholesterol.Our results suggest that Patched may contribute to cholesterol efflux from cells, and to modulation of the intracellular cholesterol concentration. This activity is likely responsible for the inhibition of the enrichment of Smoothened in the plasma membrane, which is an important step in Shh pathway activation.

  16. Transport of cholesterol autoxidation products in rabbit lipoproteins

    International Nuclear Information System (INIS)

    Peng, Shi-Kaung; Phillips, G.A.; Xia, Guang-Zhi; Morin, R.J.

    1987-01-01

    Radiolabeled pure [4- 14 C] cholesterol was kept at 60 0 C under air to autoxidize for 5 weeks, after which approximately 12% cholesterol oxidation products were formed. The mixture, suspended in gelatin, was given to rabbits by gastric gavage. Rabbits were killed 4, 24 and 48 h after treatment. Cholesterol and its autoxidation products were separated by thin-layer chromatography into 5 fractions and radioactivities of each fraction were measured. Percentages of each fraction of cholesterol oxidation products and cholesterol in the original mixture before administration and in the rabbit sera after administration were similar, suggesting that the rates of absorption of cholesterol oxidation products are not significantly different from that of cholesterol. Lipoproteins were fractioned by ultracentrifugation into VLDL, LDL and HDL. Radioactivities of each fraction in lipoproteins separated by thin layer chromatography showed that fractions containing cholestane-3β, 5α, 6β-triol, 7α- and 7β-hydroxycholesterol and 7-ketocholesterol were more selectively transported in VLDL, whereas most of the 25-hydroxycholesterol was present in LDL. HDL contained only minute amounts of cholesterol oxidation products. 22 refs

  17. CUP-1 Is a Novel Protein Involved in Dietary Cholesterol Uptake in Caenorhabditis elegans

    Science.gov (United States)

    Valdes, Victor J.; Athie, Alejandro; Salinas, Laura S.; Navarro, Rosa E.; Vaca, Luis

    2012-01-01

    Sterols transport and distribution are essential processes in all multicellular organisms. Survival of the nematode Caenorhabditis elegans depends on dietary absorption of sterols present in the environment. However the general mechanisms associated to sterol uptake in nematodes are poorly understood. In the present work we provide evidence showing that a previously uncharacterized transmembrane protein, designated Cholesterol Uptake Protein-1 (CUP-1), is involved in dietary cholesterol uptake in C. elegans. Animals lacking CUP-1 showed hypersensitivity to cholesterol limitation and were unable to uptake cholesterol. A CUP-1-GFP fusion protein colocalized with cholesterol-rich vesicles, endosomes and lysosomes as well as the plasma membrane. Additionally, by FRET imaging, a direct interaction was found between the cholesterol analog DHE and the transmembrane “cholesterol recognition/interaction amino acid consensus” (CRAC) motif present in C. elegans CUP-1. In-silico analysis identified two mammalian homologues of CUP-1. Most interestingly, CRAC motifs are conserved in mammalian CUP-1 homologous. Our results suggest a role of CUP-1 in cholesterol uptake in C. elegans and open up the possibility for the existence of a new class of proteins involved in sterol absorption in mammals. PMID:22479487

  18. Acrolein impairs the cholesterol transport functions of high density lipoproteins.

    Science.gov (United States)

    Chadwick, Alexandra C; Holme, Rebecca L; Chen, Yiliang; Thomas, Michael J; Sorci-Thomas, Mary G; Silverstein, Roy L; Pritchard, Kirkwood A; Sahoo, Daisy

    2015-01-01

    High density lipoproteins (HDL) are considered athero-protective, primarily due to their role in reverse cholesterol transport, where they transport cholesterol from peripheral tissues to the liver for excretion. The current study was designed to determine the impact of HDL modification by acrolein, a highly reactive aldehyde found in high abundance in cigarette smoke, on the cholesterol transport functions of HDL. HDL was chemically-modified with acrolein and immunoblot and mass spectrometry analyses confirmed apolipoprotein crosslinking, as well as acrolein adducts on apolipoproteins A-I and A-II. The ability of acrolein-modified HDL (acro-HDL) to serve as an acceptor of free cholesterol (FC) from COS-7 cells transiently expressing SR-BI was significantly decreased. Further, in contrast to native HDL, acro-HDL promotes higher neutral lipid accumulation in murine macrophages as judged by Oil Red O staining. The ability of acro-HDL to mediate efficient selective uptake of HDL-cholesteryl esters (CE) into SR-BI-expressing cells was reduced compared to native HDL. Together, the findings from our studies suggest that acrolein modification of HDL produces a dysfunctional particle that may ultimately promote atherogenesis by impairing functions that are critical in the reverse cholesterol transport pathway.

  19. Absorption and transport of cholesterol autoxidation derivatives in rabbits

    International Nuclear Information System (INIS)

    Peng, S.K.; Morin, R.J.; Phillips, G.A.; Xia, G.Z.

    1986-01-01

    Spontaneously autoxidized products of cholesterol have been demonstrated to be angiotoxic and possibly atherogenic. This study investigates the absorption and transport of these cholesterol oxidation derivatives (COD's) as compared to cholesterol. 14 C-labeled cholesterol autoxidized by incubation in a 60 0 C water bath for 5 weeks, then suspended in gelatin and given to New Zealand white rabbits by gastric gavage. Rabbits were sacrificed 24 hours after treatment. COD's were separated by thin layer chromatography (TLC) and radioactivities of each COD and cholesterol were measured. Percentages of each COD and cholesterol in the original mixture before administration and in the rabbits' serum after administration are almost identical, suggesting that the rates of absorption of COD's are not significantly different from that of cholesterol. Lipoproteins were fractionated by ultracentrifugation into VLDL, LDL and HDL. Radioactivities of each COD separated by TLC in each lipoprotein fraction showed that cholestane-3β,5α,6β-triol, 7α- and 7β-hydroxycholesterol and 7-ketocholesterol were predominantly present in VLDL (3 x serum concentration) and 25-hydroxycholesterol was predominantly in LDL (2.5 x serum concentration). HDL contained only minute amounts of COD's. The increased levels of COD's in VLDL and LDL may contribute to the atherogenicity of these lipoprotein

  20. Voluntary exercise increases cholesterol efflux but not macrophage reverse cholesterol transport in vivo in mice

    Directory of Open Access Journals (Sweden)

    Kuipers Folkert

    2010-07-01

    Full Text Available Abstract Physical exercise beneficially impacts on the plasma lipoprotein profile as well as on the incidence of cardiovascular events and is therefore recommended in primary and secondary prevention strategies against atherosclerotic cardiovascular disease. However, the underlying mechanisms of the protective effect of exercise remain largely unknown. Therefore, the present study tested the hypothesis that voluntary exercise in mice impacts on cholesterol efflux and in vivo reverse cholesterol transport (RCT. After two weeks of voluntary wheel running (average 10.1 ± 1.4 km/day plasma triglycerides were lower (p

  1. The cholesterol transporter ABCG1 links cholesterol homeostasis and tumour immunity.

    Science.gov (United States)

    Sag, Duygu; Cekic, Caglar; Wu, Runpei; Linden, Joel; Hedrick, Catherine C

    2015-02-27

    ATP-binding cassette transporter G1 (ABCG1) promotes cholesterol efflux from cells and regulates intracellular cholesterol homeostasis. Here we demonstrate a role of ABCG1 as a mediator of tumour immunity. Abcg1(-/-) mice have dramatically suppressed subcutaneous MB49-bladder carcinoma and B16-melanoma growth and prolonged survival. We show that reduced tumour growth in Abcg1(-/-) mice is myeloid cell intrinsic and is associated with a phenotypic shift of the macrophages from a tumour-promoting M2 to a tumour-fighting M1 within the tumour. Abcg1(-/-) macrophages exhibit an intrinsic bias towards M1 polarization with increased NF-κB activation and direct cytotoxicity for tumour cells in vitro. Overall, our study demonstrates that the absence of ABCG1 inhibits tumour growth through modulation of macrophage function within the tumour, and illustrates a link between cholesterol homeostasis and cancer.

  2. Impaired reverse cholesterol transport and hepatic steatosis ...

    African Journals Online (AJOL)

    DOAJ), African Journal Online, Bioline International, Open-J-Gate and Pharmacy Abstracts ..... membrane receptors responsible for uptake of .... for valuable discussion and revision. .... binding protein and Sp1 is specifically disrupted by the.

  3. Transporters for the Intestinal Absorption of Cholesterol, Vitamin E, and Vitamin K.

    Science.gov (United States)

    Yamanashi, Yoshihide; Takada, Tappei; Kurauchi, Ryoya; Tanaka, Yusuke; Komine, Toko; Suzuki, Hiroshi

    2017-04-03

    Humans cannot synthesize fat-soluble vitamins such as vitamin E and vitamin K. For this reason, they must be obtained from the diet via intestinal absorption. As the deficiency or excess of these vitamins has been reported to cause several types of diseases and disorders in humans, the intestinal absorption of these nutrients must be properly regulated to ensure good health. However, the mechanism of their intestinal absorption remains poorly understood. Recent studies on cholesterol using genome-edited mice, genome-wide association approaches, gene mutation analyses, and the development of cholesterol absorption inhibitors have revealed that several membrane proteins play crucial roles in the intestinal absorption of cholesterol. Surprisingly, detailed analyses of these cholesterol transporters have revealed that they can also transport vitamin E and vitamin K, providing clues to uncover the molecular mechanisms underlying the intestinal absorption of these fat-soluble vitamins. In this review, we focus on the membrane proteins (Niemann-Pick C1 like 1, scavenger receptor class B type I, cluster of differentiation 36, and ATP-binding cassette transporter A1) that are (potentially) involved in the intestinal absorption of cholesterol, vitamin E, and vitamin K and discuss their physiological and pharmacological importance. We also discuss the related uncertainties that need to be explored in future studies.

  4. Cholesterol-induced conformational changes in the sterol-sensing domain of the Scap protein suggest feedback mechanism to control cholesterol synthesis.

    Science.gov (United States)

    Gao, Yansong; Zhou, Yulian; Goldstein, Joseph L; Brown, Michael S; Radhakrishnan, Arun

    2017-05-26

    Scap is a polytopic protein of endoplasmic reticulum (ER) membranes that transports sterol regulatory element-binding proteins to the Golgi complex for proteolytic activation. Cholesterol accumulation in ER membranes prevents Scap transport and decreases cholesterol synthesis. Previously, we provided evidence that cholesterol inhibition is initiated when cholesterol binds to loop 1 of Scap, which projects into the ER lumen. Within cells, this binding causes loop 1 to dissociate from loop 7, another luminal Scap loop. However, we have been unable to demonstrate this dissociation when we added cholesterol to isolated complexes of loops 1 and 7. We therefore speculated that the dissociation requires a conformational change in the intervening polytopic sequence separating loops 1 and 7. Here we demonstrate such a change using a protease protection assay in sealed membrane vesicles. In the absence of cholesterol, trypsin or proteinase K cleaved cytosolic loop 4, generating a protected fragment that we visualized with a monoclonal antibody against loop 1. When cholesterol was added to these membranes, cleavage in loop 4 was abolished. Because loop 4 is part of the so-called sterol-sensing domain separating loops 1 and 7, these results support the hypothesis that cholesterol binding to loop 1 alters the conformation of the sterol-sensing domain. They also suggest that this conformational change helps transmit the cholesterol signal from loop 1 to loop 7, thereby allowing separation of the loops and facilitating the feedback inhibition of cholesterol synthesis. These insights suggest a new structural model for cholesterol-mediated regulation of Scap activity. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Rethinking reverse cholesterol transport and dysfunctional high-density lipoproteins.

    Science.gov (United States)

    Gillard, Baiba K; Rosales, Corina; Xu, Bingqing; Gotto, Antonio M; Pownall, Henry J

    2018-04-12

    Human plasma high-density lipoprotein cholesterol concentrations are a negative risk factor for atherosclerosis-linked cardiovascular disease. Pharmacological attempts to reduce atherosclerotic cardiovascular disease by increasing plasma high-density lipoprotein cholesterol have been disappointing so that recent research has shifted from HDL quantity to HDL quality, that is, functional vs dysfunctional HDL. HDL has varying degrees of dysfunction reflected in impaired reverse cholesterol transport (RCT). In the context of atheroprotection, RCT occurs by 2 mechanisms: one is the well-known trans-hepatic pathway comprising macrophage free cholesterol (FC) efflux, which produces early forms of FC-rich nascent HDL (nHDL). Lecithin:cholesterol acyltransferase converts HDL-FC to HDL-cholesteryl ester while converting nHDL from a disc to a mature spherical HDL, which transfers its cholesteryl ester to the hepatic HDL receptor, scavenger receptor B1 for uptake, conversion to bile salts, or transfer to the intestine for excretion. Although widely cited, current evidence suggests that this is a minor pathway and that most HDL-FC and nHDL-FC rapidly transfer directly to the liver independent of lecithin:cholesterol acyltransferase activity. A small fraction of plasma HDL-FC enters the trans-intestinal efflux pathway comprising direct FC transfer to the intestine. SR-B1 -/- mice, which have impaired trans-hepatic FC transport, are characterized by high plasma levels of a dysfunctional FC-rich HDL that increases plasma FC bioavailability in a way that produces whole-body hypercholesterolemia and multiple pathologies. The design of future therapeutic strategies to improve RCT will have to be formulated in the context of these dual RCT mechanisms and the role of FC bioavailability. Copyright © 2018 National Lipid Association. Published by Elsevier Inc. All rights reserved.

  6. Immuno-histochemical localization of cholesterol binding proteins in ...

    African Journals Online (AJOL)

    This manuscript aims to investigate immunocytochemical localization of cholesterol binding proteins (CBPs) in semi-thin sections of midgut of Schistocerca gregaria (Forskal). For this purpose ... Further, same protein was also localized in other tissues like fat body, testis, and ovary of male and female insects of S. gregaria.

  7. Human immunodeficiency virus impairs reverse cholesterol transport from macrophages.

    Directory of Open Access Journals (Sweden)

    Zahedi Mujawar

    2006-10-01

    Full Text Available Several steps of HIV-1 replication critically depend on cholesterol. HIV infection is associated with profound changes in lipid and lipoprotein metabolism and an increased risk of coronary artery disease. Whereas numerous studies have investigated the role of anti-HIV drugs in lipodystrophy and dyslipidemia, the effects of HIV infection on cellular cholesterol metabolism remain uncharacterized. Here, we demonstrate that HIV-1 impairs ATP-binding cassette transporter A1 (ABCA1-dependent cholesterol efflux from human macrophages, a condition previously shown to be highly atherogenic. In HIV-1-infected cells, this effect was mediated by Nef. Transfection of murine macrophages with Nef impaired cholesterol efflux from these cells. At least two mechanisms were found to be responsible for this phenomenon: first, HIV infection and transfection with Nef induced post-transcriptional down-regulation of ABCA1; and second, Nef caused redistribution of ABCA1 to the plasma membrane and inhibited internalization of apolipoprotein A-I. Binding of Nef to ABCA1 was required for down-regulation and redistribution of ABCA1. HIV-infected and Nef-transfected macrophages accumulated substantial amounts of lipids, thus resembling foam cells. The contribution of HIV-infected macrophages to the pathogenesis of atherosclerosis was supported by the presence of HIV-positive foam cells in atherosclerotic plaques of HIV-infected patients. Stimulation of cholesterol efflux from macrophages significantly reduced infectivity of the virions produced by these cells, and this effect correlated with a decreased amount of virion-associated cholesterol, suggesting that impairment of cholesterol efflux is essential to ensure proper cholesterol content in nascent HIV particles. These results reveal a previously unrecognized dysregulation of intracellular lipid metabolism in HIV-infected macrophages and identify Nef and ABCA1 as the key players responsible for this effect. Our findings

  8. Lack of P2Y(13) in mice fed a high cholesterol diet results in decreased hepatic cholesterol content, biliary lipid secretion and reverse cholesterol transport

    NARCIS (Netherlands)

    Lichtenstein, Laeticia; Serhan, Nizar; Annema, Wijtske; Combes, Guillaume; Robaye, Bernard; Boeynaems, Jean-Marie; Perret, Bertrand; Tietge, Uwe J. F.; Laffargue, Muriel; Martinez, Laurent O.

    2013-01-01

    Background: The protective effect of HDL is mostly attributed to their metabolic function in reverse cholesterol transport (RCT), a process whereby excess cellular cholesterol is taken up from peripheral cells, processed in HDL particles, and later delivered to the liver for further metabolism and

  9. Reverse Cholesterol Transport: Molecular Mechanisms and the Non-medical Approach to Enhance HDL Cholesterol

    Directory of Open Access Journals (Sweden)

    Leandro R. Marques

    2018-05-01

    Full Text Available Dyslipidemia (high concentrations of LDL-c and low concentrations of HDL-c is a major cause of cardiovascular events, which are the leading cause of death in the world. On the other hand, nutrition and regular exercise can be an interesting strategy to modulate lipid profile, acting as prevention or treatment, inhibiting the risk of diseases due to its anti-inflammatory and anti-atherogenic characteristics. Additionally, the possibility of controlling different training variables, such as type, intensity and recovery interval, can be used to maximize the benefits of exercise in promoting cardiovascular health. However, the mechanisms by which exercise and nutrients act in the regulation of cholesterol and its fractions, such as reverse cholesterol transport, receptors and transcription factors involved, such as PPARs and their role related to exercise, deserve further discussion. Therefore, the objective of this review is to debate about non-medical approaches to increase HDL-c, such as nutritional and training strategies, and to discuss the central mechanisms involved in the modulation of lipid profile during exercise, as well as that can be controlled by physical trainers or sports specialists in attempt to maximize the benefits promoted by exercise. The search for papers was performed in the databases: Medline (Pubmed, Science Direct, Scopus, Sport Discus, Web of Science, Scielo and Lilacs until February 2016.

  10. Differential effects of gemfibrozil and fenofibrate on reverse cholesterol transport from macrophages to feces in vivo.

    Science.gov (United States)

    Rotllan, Noemí; Llaverías, Gemma; Julve, Josep; Jauhiainen, Matti; Calpe-Berdiel, Laura; Hernández, Cristina; Simó, Rafael; Blanco-Vaca, Francisco; Escolà-Gil, Joan Carles

    2011-02-01

    Gemfibrozil and fenofibrate, two of the fibrates most used in clinical practice, raise HDL cholesterol (HDLc) and are thought to reduce the risk of atherosclerotic cardiovascular disease. These drugs act as PPARα agonists and upregulate the expression of genes crucial in reverse cholesterol transport (RCT). In the present study, we determined the effects of these two fibrates on RCT from macrophages to feces in vivo in human apoA-I transgenic (hApoA-ITg) mice. [(3)H]cholesterol-labeled mouse macrophages were injected intraperitoneally into hApoA-ITg mice treated with intragastric doses of fenofibrate, gemfibrozil or a vehicle solution for 17days, and radioactivity was determined in plasma, liver and feces. Fenofibrate, but not gemfibrozil, enhanced [(3)H]cholesterol flux to plasma and feces of female hApoA-ITg mice. Fenofibrate significantly increased plasma HDLc, HDL phospholipids, hApoA-I levels and phospholipid transfer protein activity, whereas these parameters were not altered by gemfibrozil treatment. Unlike gemfibrozil, fenofibrate also induced the generation of larger HDL particles, which were more enriched in cholesteryl esters, together with higher potential to generate preβ-HDL formation and caused a significant increase in [(3)H]cholesterol efflux to plasma. Our findings demonstrate that fenofibrate promotes RCT from macrophages to feces in vivo and, thus, highlight a differential action of this fibrate on HDL. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. LDL Receptor-Related Protein-1 (LRP1 Regulates Cholesterol Accumulation in Macrophages.

    Directory of Open Access Journals (Sweden)

    Anna P Lillis

    Full Text Available Within the circulation, cholesterol is transported by lipoprotein particles and is taken up by cells when these particles associate with cellular receptors. In macrophages, excessive lipoprotein particle uptake leads to foam cell formation, which is an early event in the development of atherosclerosis. Currently, mechanisms responsible for foam cell formation are incompletely understood. To date, several macrophage receptors have been identified that contribute to the uptake of modified forms of lipoproteins leading to foam cell formation, but the in vivo contribution of the LDL receptor-related protein 1 (LRP1 to this process is not known [corrected]. To investigate the role of LRP1 in cholesterol accumulation in macrophages, we generated mice with a selective deletion of LRP1 in macrophages on an LDL receptor (LDLR-deficient background (macLRP1-/-. After feeding mice a high fat diet for 11 weeks, peritoneal macrophages isolated from Lrp+/+ mice contained significantly higher levels of total cholesterol than those from macLRP1-/- mice. Further analysis revealed that this was due to increased levels of cholesterol esters. Interestingly, macLRP1-/- mice displayed elevated plasma cholesterol and triglyceride levels resulting from accumulation of large, triglyceride-rich lipoprotein particles in the circulation. This increase did not result from an increase in hepatic VLDL biosynthesis, but rather results from a defect in catabolism of triglyceride-rich lipoprotein particles in macLRP1-/- mice. These studies reveal an important in vivo contribution of macrophage LRP1 to cholesterol homeostasis.

  12. [A history and review of cholesterol ester transfer protein inhibitors and their contribution to the understanding of the physiology and pathophysiology of high density lipoprotein].

    Science.gov (United States)

    Corral, Pablo; Schreier, Laura

    2014-01-01

    There is irrefutable evidence that statins reduce the risk of cardiovascular events in a magnitude proportional to the intensity of the decrease in cholesterol transport by the low density lipoproteins. Despite this great advance there is still a residual risk of cardiovascular events. For this reason, an increase in the levels of high density lipoprotein is considered in order to boost the main action of this lipoprotein, which is reverse cholesterol transport. Distinct classes of evidence (epidemiological, genetic, and pathophysiological) show that the inhibition and/or modulation of cholesterol ester transfer protein increases plasma high density lipoprotein-cholesterol levels. The main reason for presenting this review is to look at the physiology of cholesterol ester transfer protein, its interrelationship with high density lipoproteins, and to give an update on the development of different cholesterol ester transfer protein inhibitor/modulator molecules. Copyright © 2013 Elsevier España, S.L. y SEA. All rights reserved.

  13. Localization of the placental BCRP/ABCG2 transporter to lipid rafts: Role for cholesterol in mediating efflux activity.

    Science.gov (United States)

    Szilagyi, John T; Vetrano, Anna M; Laskin, Jeffrey D; Aleksunes, Lauren M

    2017-07-01

    The breast cancer resistance protein (BCRP/ABCG2) is an efflux transporter in the placental barrier. By transporting chemicals from the fetal to the maternal circulation, BCRP limits fetal exposure to a range of drugs, toxicants, and endobiotics such as bile acids and hormones. The purpose of the present studies was to 1) determine whether BCRP localizes to highly-ordered, cholesterol-rich lipid raft microdomains in placenta microvillous membranes, and 2) determine the impact of cholesterol on BCRP-mediated placental transport in vitro. BCRP expression was analyzed in lipid rafts isolated from placentas from healthy, term pregnancies and BeWo trophoblasts by density gradient ultracentrifugation. BeWo cells were also tested for their ability to efflux BCRP substrates after treatment with the cholesterol sequestrant methyl-β-cyclodextrin (MβCD, 5 mM, 1 h) or the cholesterol synthesis inhibitor pravastatin (200 μM, 48 h). BCRP was found to co-localize with lipid raft proteins in detergent-resistant, lipid raft-containing fractions from placental microvillous membranes and BeWo cells. Treatment of BeWo cells with MβCD redistributed BCRP protein into higher density non-lipid raft fractions. Repletion of the cells with cholesterol restored BCRP localization to lipid raft-containing fractions. Treatment of BeWo cells with MβCD or pravastatin increased cellular retention of two BCRP substrates, the fluorescent dye Hoechst 33342 and the mycotoxin zearalenone. Repletion with cholesterol restored BCRP transporter activity. Taken together, these data demonstrate that cholesterol may play a critical role in the post-translational regulation of BCRP in placental lipid rafts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Lower Squalene Epoxidase and Higher Scavenger Receptor Class B Type 1 Protein Levels Are Involved in Reduced Serum Cholesterol Levels in Stroke-Prone Spontaneously Hypertensive Rats.

    Science.gov (United States)

    Michihara, Akihiro; Mido, Mayuko; Matsuoka, Hiroshi; Mizutani, Yurika

    2015-01-01

    A lower serum cholesterol level was recently shown to be one of the causes of stroke in an epidemiological study. Spontaneously hypertensive rats stroke-prone (SHRSP) have lower serum cholesterol levels than normotensive Wistar-Kyoto rats (WKY). To elucidate the mechanisms responsible for the lower serum cholesterol levels in SHRSP, we determined whether the amounts of cholesterol biosynthetic enzymes or the receptor and transporter involved in cholesterol uptake and efflux in the liver were altered in SHRSP. When the mRNA levels of seven cholesterol biosynthetic enzymes were measured using real-time polymerase chain reaction (PCR), farnesyl pyrophosphate synthase and squalene epoxidase (SQE) levels in the liver of SHRSP were significantly lower than those in WKY. SQE protein levels were significantly reduced in tissues other than the brain of SHRSP. No significant differences were observed in low-density lipoprotein (LDL) receptor (uptake of serum LDL-cholesterol) or ATP-binding cassette transporter A1 (efflux of cholesterol from the liver/formation of high-density lipoprotein (HDL)) protein levels in the liver and testis between SHRSP and WKY, whereas scavenger receptor class B type 1 (SRB1: uptake of serum HDL-cholesterol) protein levels were higher in the livers of SHRSP. These results indicated that the lower protein levels of SQE and higher protein levels of SRB1 in the liver were involved in the reduced serum cholesterol levels in SHRSP.

  15. Common structural features of cholesterol binding sites in crystallized soluble proteins.

    Science.gov (United States)

    Bukiya, Anna N; Dopico, Alejandro M

    2017-06-01

    Cholesterol-protein interactions are essential for the architectural organization of cell membranes and for lipid metabolism. While cholesterol-sensing motifs in transmembrane proteins have been identified, little is known about cholesterol recognition by soluble proteins. We reviewed the structural characteristics of binding sites for cholesterol and cholesterol sulfate from crystallographic structures available in the Protein Data Bank. This analysis unveiled key features of cholesterol-binding sites that are present in either all or the majority of sites: i ) the cholesterol molecule is generally positioned between protein domains that have an organized secondary structure; ii ) the cholesterol hydroxyl/sulfo group is often partnered by Asn, Gln, and/or Tyr, while the hydrophobic part of cholesterol interacts with Leu, Ile, Val, and/or Phe; iii ) cholesterol hydrogen-bonding partners are often found on α-helices, while amino acids that interact with cholesterol's hydrophobic core have a slight preference for β-strands and secondary structure-lacking protein areas; iv ) the steroid's C21 and C26 constitute the "hot spots" most often seen for steroid-protein hydrophobic interactions; v ) common "cold spots" are C8-C10, C13, and C17, at which contacts with the proteins were not detected. Several common features we identified for soluble protein-steroid interaction appear evolutionarily conserved. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  16. Impact of LDL apheresis on atheroprotective reverse cholesterol transport pathway in familial hypercholesterolemia

    NARCIS (Netherlands)

    Orsoni, Alexina; Villard, Elise F.; Bruckert, Eric; Robillard, Paul; Carrie, Alain; Bonnefont-Rousselot, Dominique; Chapman, M. John; Dallinga-Thie, Geesje M.; Le Goff, Wilfried; Guerin, Maryse

    2012-01-01

    In familial hypercholesterolemia (FH), low HDL cholesterol (HDL-C) levels are associated with functional alterations of HDL particles that reduce their capacity to mediate the reverse cholesterol transport (RCT) pathway. The objective of this study was to evaluate the consequences of LDL apheresis

  17. Role of Hepatic Lipase and Endothelial Lipase in High-Density Lipoprotein-Mediated Reverse Cholesterol Transport

    NARCIS (Netherlands)

    Annema, Wijtske; Tietge, Uwe J. F.

    Reverse cholesterol transport (RCT) constitutes a key part of the atheroprotective properties of high-density lipoproteins (HDL). Hepatic lipase (HL) and endothelial lipase (EL) are negative regulators of plasma HDL cholesterol levels. Although overexpression of EL decreases overall

  18. The ABCG5/8 Cholesterol Transporter and Myocardial Infarction Versus Gallstone Disease

    DEFF Research Database (Denmark)

    Stender, Stefan; Frikke-Schmidt, Ruth; Nordestgaard, Børge G

    2014-01-01

    OBJECTIVES: The study sought to test the hypothesis that genetic variation in ABCG5/8, the transporter responsible for intestinal and hepatobiliary cholesterol efflux, may simultaneously influence plasma and biliary cholesterol levels, and hence risk of myocardial infarction (MI) and gallstone...... disease in opposite directions. BACKGROUND: High plasma levels of low-density lipoprotein (LDL) cholesterol are a causal risk factor for MI, whereas high levels of biliary cholesterol promote gallstone formation. METHODS: A total of 60,239 subjects from Copenhagen were included, including 5,647 with MI...... and 3,174 with symptomatic gallstone disease. Subjects were genotyped for 6 common, nonsynonymous and functional variants in ABCG5/8, and a combined weighted genotype score was calculated. RESULTS: Combined, weighted genotype scores were associated with stepwise decreases in LDL cholesterol of up to 5...

  19. Cholesterol as a co-solvent and a ligand for membrane proteins

    Science.gov (United States)

    Song, Yuanli; Kenworthy, Anne K; Sanders, Charles R

    2014-01-01

    As of mid 2013 a Medline search on “cholesterol” yielded over 200,000 hits, reflecting the prominence of this lipid in numerous aspects of animal cell biology and physiology under conditions of health and disease. Aberrations in cholesterol homeostasis underlie both a number of rare genetic disorders and contribute to common sporadic and complex disorders including heart disease, stroke, type II diabetes, and Alzheimer's disease. The corresponding author of this review and his lab stumbled only recently into the sprawling area of cholesterol research when they discovered that the amyloid precursor protein (APP) binds cholesterol, a topic covered by the Hans Neurath Award lecture at the 2013 Protein Society Meeting. Here, we first provide a brief overview of cholesterol-protein interactions and then offer our perspective on how and why binding of cholesterol to APP and its C99 domain (β-CTF) promotes the amyloidogenic pathway, which is closely related to the etiology of Alzheimer's disease. PMID:24155031

  20. Fluorescent Sterols and Cholesteryl Esters as Probes for Intracellular Cholesterol Transport

    Science.gov (United States)

    Solanko, Katarzyna A.; Modzel, Maciej; Solanko, Lukasz M.; Wüstner, Daniel

    2015-01-01

    Cholesterol transport between cellular organelles comprised vesicular trafficking and nonvesicular exchange; these processes are often studied by quantitative fluorescence microscopy. A major challenge for using this approach is producing analogs of cholesterol with suitable brightness and structural and chemical properties comparable with those of cholesterol. This review surveys currently used fluorescent sterols with respect to their behavior in model membranes, their photophysical properties, as well as their transport and metabolism in cells. In the first part, several intrinsically fluorescent sterols, such as dehydroergosterol or cholestatrienol, are discussed. These polyene sterols (P-sterols) contain three conjugated double bonds in the steroid ring system, giving them slight fluorescence in ultraviolet light. We discuss the properties of P-sterols relative to cholesterol, outline their chemical synthesis, and explain how to image them in living cells and organisms. In particular, we show that P-sterol esters inserted into low-density lipoprotein can be tracked in the fibroblasts of Niemann–Pick disease using high-resolution deconvolution microscopy. We also describe fluorophore-tagged cholesterol probes, such as BODIPY-, NBD-, Dansyl-, or Pyrene-tagged cholesterol, and eventual esters of these analogs. Finally, we survey the latest developments in the synthesis and use of alkyne cholesterol analogs to be labeled with fluorophores by click chemistry and discuss the potential of all approaches for future applications. PMID:27330304

  1. Water-transporting proteins

    DEFF Research Database (Denmark)

    Zeuthen, Thomas

    2010-01-01

    . In the K(+)/Cl(-) and the Na(+)/K(+)/2Cl(-) cotransporters, water is entirely cotransported, while water transport in glucose uniporters and Na(+)-coupled transporters of nutrients and neurotransmitters takes place by both osmosis and cotransport. The molecular mechanism behind cotransport of water...... transport. Epithelial water transport is energized by the movements of ions, but how the coupling takes place is uncertain. All epithelia can transport water uphill against an osmotic gradient, which is hard to explain by simple osmosis. Furthermore, genetic removal of aquaporins has not given support...... to osmosis as the exclusive mode of transport. Water cotransport can explain the coupling between ion and water transport, a major fraction of transepithelial water transport and uphill water transport. Aquaporins enhance water transport by utilizing osmotic gradients and cause the osmolarity...

  2. Potential of BODIPY-cholesterol for analysis of cholesterol transport and diffusion in living cells

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Lund, Frederik Wendelboe; Röhrl, Clemens

    2016-01-01

    and collaborative efforts with Bob Bittman for studying diffusion in the plasma membrane (PM) and uptake of BChol in a quantitative manner. For that purpose, we used a variety of fluorescence approaches including fluorescence correlation spectroscopy and its imaging variants, fluorescence recovery after...... photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP). We also describe pulse-chase studies from the PM using BChol in direct comparison to DHE. Based on the gathered imaging data, we present a two-step kinetic model for sterol transport between PM and recycling endosomes. In addition, we...

  3. Mutations of the central tyrosines of putative cholesterol recognition amino acid consensus (CRAC) sequences modify folding, activity, and sterol-sensing of the human ABCG2 multidrug transporter.

    Science.gov (United States)

    Gál, Zita; Hegedüs, Csilla; Szakács, Gergely; Váradi, András; Sarkadi, Balázs; Özvegy-Laczka, Csilla

    2015-02-01

    Human ABCG2 is a plasma membrane glycoprotein causing multidrug resistance in cancer. Membrane cholesterol and bile acids are efficient regulators of ABCG2 function, while the molecular nature of the sterol-sensing sites has not been elucidated. The cholesterol recognition amino acid consensus (CRAC, L/V-(X)(1-5)-Y-(X)(1-5)-R/K) sequence is one of the conserved motifs involved in cholesterol binding in several proteins. We have identified five potential CRAC motifs in the transmembrane domain of the human ABCG2 protein. In order to define their roles in sterol-sensing, the central tyrosines of these CRACs (Y413, 459, 469, 570 and 645) were mutated to S or F and the mutants were expressed both in insect and mammalian cells. We found that mutation in Y459 prevented protein expression; the Y469S and Y645S mutants lost their activity; while the Y570S, Y469F, and Y645F mutants retained function as well as cholesterol and bile acid sensitivity. We found that in the case of the Y413S mutant, drug transport was efficient, while modulation of the ATPase activity by cholesterol and bile acids was significantly altered. We suggest that the Y413 residue within a putative CRAC motif has a role in sterol-sensing and the ATPase/drug transport coupling in the ABCG2 multidrug transporter. Copyright © 2014. Published by Elsevier B.V.

  4. Cholesterol activates the G-protein coupled receptor Smoothened to promote Hedgehog signaling

    Science.gov (United States)

    Luchetti, Giovanni; Sircar, Ria; Kong, Jennifer H; Nachtergaele, Sigrid; Sagner, Andreas; Byrne, Eamon FX; Covey, Douglas F; Siebold, Christian; Rohatgi, Rajat

    2016-01-01

    Cholesterol is necessary for the function of many G-protein coupled receptors (GPCRs). We find that cholesterol is not just necessary but also sufficient to activate signaling by the Hedgehog (Hh) pathway, a prominent cell-cell communication system in development. Cholesterol influences Hh signaling by directly activating Smoothened (SMO), an orphan GPCR that transmits the Hh signal across the membrane in all animals. Unlike many GPCRs, which are regulated by cholesterol through their heptahelical transmembrane domains, SMO is activated by cholesterol through its extracellular cysteine-rich domain (CRD). Residues shown to mediate cholesterol binding to the CRD in a recent structural analysis also dictate SMO activation, both in response to cholesterol and to native Hh ligands. Our results show that cholesterol can initiate signaling from the cell surface by engaging the extracellular domain of a GPCR and suggest that SMO activity may be regulated by local changes in cholesterol abundance or accessibility. DOI: http://dx.doi.org/10.7554/eLife.20304.001 PMID:27705744

  5. Following Intracellular Cholesterol Transport by Linear and Non-Linear Optical Microscopy of Intrinsically Fluorescent Sterols

    DEFF Research Database (Denmark)

    Wustner, D.

    2012-01-01

    Elucidation of intracellular cholesterol transport is important for understanding the molecular basis of several metabolic and neuronal diseases, like atheroclerosis or lysosomal storage disorders. Progress in this field depends crucially on the development of new technical approaches to follow...... is on recent developments in imaging technology to follow the intracellular fate of intrinsically fluorescent sterols as faithful cholesterol markers. In particular, UV-sensitive wide field and multiphoton microscopy of the sterol dehydroergosterol, DHE, is explained and new methods of quantitative image...... analysis like pixel-wise bleach rate fitting and multiphoton image correlation spectroscopy are introduced. Several applications of the new technology including observation of vectorial sterol trafficking in polarized human hepatoma cells for investigation of reverse cholesterol transport are presented....

  6. Tritium labelling of a cholesterol amphiphile designed for cell membrane anchoring of proteins.

    Science.gov (United States)

    Schäfer, Balázs; Orbán, Erika; Kele, Zoltán; Tömböly, Csaba

    2015-01-01

    Cell membrane association of proteins can be achieved by the addition of lipid moieties to the polypeptide chain, and such lipid-modified proteins have important biological functions. A class of cell surface proteins contains a complex glycosylphosphatidylinositol (GPI) glycolipid at the C-terminus, and they are accumulated in cholesterol-rich membrane microdomains, that is, lipid rafts. Semisynthetic lipoproteins prepared from recombinant proteins and designed lipids are valuable probes and model systems of the membrane-associated proteins. Because GPI-anchored proteins can be reinserted into the cell membrane with the retention of the biological function, they are appropriate candidates for preparing models via reduction of the structural complexity. A synthetic headgroup was added to the 3β-hydroxyl group of cholesterol, an essential lipid component of rafts, and the resulting cholesterol derivative was used as a simplified GPI mimetic. In order to quantitate the membrane integrated GPI mimetic after the exogenous addition to live cells, a tritium labelled cholesterol anchor was prepared. The radioactive label was introduced into the headgroup, and the radiolabelled GPI mimetic anchor was obtained with a specific activity of 1.37 TBq/mmol. The headgroup labelled cholesterol derivative was applied to demonstrate the sensitive detection of the cell membrane association of the anchor under in vivo conditions. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Intracellular transport of low density lipoprotein-derived cholesterol is defective in Niemann-Pick type C fibroblasts

    International Nuclear Information System (INIS)

    Liscum, L.; Ruggiero, R.M.; Faust, J.R.

    1989-01-01

    Niemann-Pick disease type C (NPC) is characterized by substantial intracellular accumulation of unesterified cholesterol. The accumulation of unesterified cholesterol in NPC fibroblasts cultured with low density lipoprotein (LDL) appears to result from the inability of LDL to stimulate cholesterol esterification in addition to impaired LDL-mediated downregulation of LDL receptor activity and cellular cholesterol synthesis. Although a defect in cholesterol transport in NPC cells has been inferred from previous studies, no experiments have been reported that measure the intracellular movement of LDL-cholesterol specifically. We have used four approaches to assess intracellular cholesterol transport in normal and NPC cells and have determined the following: (a) mevinolin-inhibited NPC cells are defective in using LDL-cholesterol for growth. However, exogenously added mevalonate restores cell growth equally in normal and NPC cells; (b) the transport of LDL-derived [3H]cholesterol to the plasma membrane is slower in NPC cells, while the rate of appearance of [3H]acetate-derived, endogenously synthesized [3H]cholesterol at the plasma membrane is the same for normal and NPC cells; (c) in NPC cells, LDL-derived [3H]cholesterol accumulates in lysosomes to higher levels than normal, resulting in defective movement to other cell membranes; and (d) incubation of cells with LDL causes an increase in cholesterol content of NPC lysosomes that is threefold greater than that observed in normal lysosomes. Our results indicate that a cholesterol transport defect exists in NPC that is specific for LDL-derived cholesterol

  8. Model of OSBP-Mediated Cholesterol Supply to Aichi Virus RNA Replication Sites Involving Protein-Protein Interactions among Viral Proteins, ACBD3, OSBP, VAP-A/B, and SAC1.

    Science.gov (United States)

    Ishikawa-Sasaki, Kumiko; Nagashima, Shigeo; Taniguchi, Koki; Sasaki, Jun

    2018-04-15

    Positive-strand RNA viruses, including picornaviruses, utilize cellular machinery for genome replication. Previously, we reported that each of the 2B, 2BC, 2C, 3A, and 3AB proteins of Aichi virus (AiV), a picornavirus, forms a complex with the Golgi apparatus protein ACBD3 and phosphatidylinositol 4-kinase IIIβ (PI4KB) at viral RNA replication sites (replication organelles [ROs]), enhancing PI4KB-dependent phosphatidylinositol 4-phosphate (PI4P) production. Here, we demonstrate AiV hijacking of the cellular cholesterol transport system involving oxysterol-binding protein (OSBP), a PI4P-binding cholesterol transfer protein. AiV RNA replication was inhibited by silencing cellular proteins known to be components of this pathway, OSBP, the ER membrane proteins VAPA and VAPB (VAP-A/B), the PI4P-phosphatase SAC1, and PI-transfer protein β. OSBP, VAP-A/B, and SAC1 were present at RNA replication sites. We also found various previously unknown interactions among the AiV proteins (2B, 2BC, 2C, 3A, and 3AB), ACBD3, OSBP, VAP-A/B, and SAC1, and the interactions were suggested to be involved in recruiting the component proteins to AiV ROs. Importantly, the OSBP-2B interaction enabled PI4P-independent recruitment of OSBP to AiV ROs, indicating preferential recruitment of OSBP among PI4P-binding proteins. Protein-protein interaction-based OSBP recruitment has not been reported for other picornaviruses. Cholesterol was accumulated at AiV ROs, and inhibition of OSBP-mediated cholesterol transfer impaired cholesterol accumulation and AiV RNA replication. Electron microscopy showed that AiV-induced vesicle-like structures were close to ER membranes. Altogether, we conclude that AiV directly recruits the cholesterol transport machinery through protein-protein interactions, resulting in formation of membrane contact sites between the ER and AiV ROs and cholesterol supply to the ROs. IMPORTANCE Positive-strand RNA viruses utilize host pathways to modulate the lipid composition of

  9. Artificial oxygen transport protein

    Science.gov (United States)

    Dutton, P. Leslie

    2014-09-30

    This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

  10. The role of cholesterol metabolism and cholesterol transport in carcinogenesis; A review of scientific findings, relevant to future cancer therapeutics.

    Directory of Open Access Journals (Sweden)

    Pedro Miguel Cruz

    2013-09-01

    Full Text Available While the unique metabolic activities of malignant tissues as potential targets for cancer therapeutics has been the subject of several recent reviews, the role of cholesterol metabolism in this context is yet to be fully explored. Cholesterol is an essential component of mammalian cell membranes as well as a precursor of bile acids and steroid hormones. The hypothesis that cancer cells need excess cholesterol and intermediates of the cholesterol biosynthesis pathway to maintain a high level of proliferation is well accepted, however the mechanisms by which malignant cells and tissues reprogram cholesterol synthesis, uptake and efflux are yet to be fully elucidated as potential therapeutic targets. High and low density plasma lipoproteins, area the likely major suppliers of cholesterol to cancer cells and tumors, potentially via receptor mediated mechanisms. This review is primarily focused on the role(s of lipoproteins in carcinogenesis, and their future roles as drug delivery vehicles for targeted cancer chemotherapy.

  11. Cholesterol transport and steroidogenesis by the corpus luteum

    Directory of Open Access Journals (Sweden)

    Christenson Lane K

    2003-11-01

    Full Text Available Abstract The synthesis of progesterone by the corpus luteum is essential for the establishment and maintenance of early pregnancy. Regulation of luteal steroidogenesis can be broken down into three major events; luteinization (i.e., conversion of an ovulatory follicle, luteal regression, and pregnancy induced luteal maintenance/rescue. While the factors that control these events and dictate the final steroid end products are widely varied among different species, the composition of the corpus luteum (luteinized thecal and granulosa cells and the enzymes and proteins involved in the steroidogenic pathway are relatively similar among all species. The key factors involved in luteal steroidogenesis and several new exciting observations regarding regulation of luteal steroidogenic function are discussed in this review.

  12. Purification and characterization of a novel cholesterol-lowering protein from the seeds of Senna obtusifolia

    Institute of Scientific and Technical Information of China (English)

    LI ChuHuai; LI Mei; CHANG WenRui; GUO BaoJiang

    2008-01-01

    "Juemingzi", a source of traditional Chinese herbal medicine, has been demonstrated to play a role in decreasing serum cholesterol concentration. In this study, a novel protein, which has shown an in-hibitory effect on cholesterol biosynthesis, was isolated from Senna obtusifolia L. seed by gel filtration and ion exchange chromatography. The novel protein's molecular mass was 19.7 kD and its pl was 4.80. Both SDS-PAGE and isoelectric-focusing (IEF) revealed a single Coomassie brilliant blue stained band, indicating that the novel protein was a single peptide. The N-terminal amino acid sequence of the pro-tein was IPYISASFPLNIEFLPSE, which had no similarity with any other protein sequences in the NCBI protein database. Circular dichroism (CD) signals indicated that S. obtusifolia seed protein contained 12.5% α-helix, 55.6% β-sheet, and 31.9% random coil.

  13. Effects of Dietary Flavonoids on Reverse Cholesterol Transport, HDL Metabolism, and HDL Function.

    Science.gov (United States)

    Millar, Courtney L; Duclos, Quinn; Blesso, Christopher N

    2017-03-01

    Strong experimental evidence confirms that HDL directly alleviates atherosclerosis. HDL particles display diverse atheroprotective functions in reverse cholesterol transport (RCT), antioxidant, anti-inflammatory, and antiapoptotic processes. In certain inflammatory disease states, however, HDL particles may become dysfunctional and proatherogenic. Flavonoids show the potential to improve HDL function through their well-documented effects on cellular antioxidant status and inflammation. The aim of this review is to summarize the basic science and clinical research examining the effects of dietary flavonoids on RCT and HDL function. Based on preclinical studies that used cell culture and rodent models, it appears that many flavonoids (e.g., anthocyanidins, flavonols, and flavone subclasses) influence RCT and HDL function beyond simple HDL cholesterol concentration by regulating cellular cholesterol efflux from macrophages and hepatic paraoxonase 1 expression and activity. In clinical studies, dietary anthocyanin intake is associated with beneficial changes in serum biomarkers related to HDL function in a variety of human populations (e.g., in those who are hyperlipidemic, hypertensive, or diabetic), including increased HDL cholesterol concentration, as well as HDL antioxidant and cholesterol efflux capacities. However, clinical research on HDL functionality is lacking for some flavonoid subclasses (e.g., flavanols, flavones, flavanones, and isoflavones). Although there has been a tremendous effort to develop HDL-targeted drug therapies, more research is warranted on how the intake of foods or specific nutrients affects HDL function. © 2017 American Society for Nutrition.

  14. Free cholesterol is a potent regulator of lipid transfer protein function

    International Nuclear Information System (INIS)

    Morton, R.E.

    1988-01-01

    This study investigates the effect of altered lipoprotein free cholesterol (FC) content on the transfer of cholesteryl ester (CE) and triglyceride (TG) from very low- (VLDL), low- (LDL), and high-(HDL) density lipoproteins by the plasma-derived lipid transfer protein (LTP). The FC content of VLDL and HDL was selectively altered by incubating these lipoproteins with FC/phospholipid dispersions of varying composition. FC-modified lipoproteins were then equilibrated with [3H] TG, [14C]CE-labeled lipoproteins of another class to facilitate the subsequent modification of the radiolabeled donor lipoproteins. LTP was added and the extent of radiolabeled TG and CE transfer determined after 1 h. With either LDL or VLDL as lipid donor, an increase in the FC content of these lipoproteins caused a concentration-dependent inhibition (up to 50%) of CE transfer from these particles, without any significant effect on TG transfer. In contrast, with HDL as donor, increasing the HDL FC content had little effect on CE transfer from HDL, but markedly stimulated (up to 2.5-fold) the transfer of TG. This differential effect of FC on the unidirectional transfer of radiolabeled lipids from VLDL and HDL led to marked effects on LTP-facilitated net mass transfer of lipids. During long-term incubation of a constant amount of LTP with FC-modified VLDL and HDL, the extent of net mass transfer was linearly related to lipoprotein FC content; a 4-fold increase in FC content resulted in a 3-fold stimulation of the CE mass transferred to VLDL, which was coupled to an equimolar, reciprocal transfer of TG mass to HDL. Since lipid transfer between lipoproteins is integral to the process of reverse cholesterol transport, we conclude that lipoprotein FC levels are a potent, positive regulator of the pathways involved in sterol clearance. FC may modulate lipid transfer by altering the availability of CE and TG to LTP at the lipoprotein surface

  15. Super-resolution microscopy reveals functional organization of dopamine transporters into cholesterol and neuronal activity-dependent nanodomains

    DEFF Research Database (Denmark)

    Rahbek-Clemmensen, Troels; Lycas, Matthew D.; Erlendsson, Simon

    2017-01-01

    is dynamically sequestrated into cholesterol-dependent nanodomains in the plasma membrane of presynaptic varicosities and neuronal projections of dopaminergic neurons. Stochastic optical reconstruction microscopy reveals irregular dopamine transporter nanodomains (∼70 nm mean diameter) that were highly sensitive...... to cholesterol depletion. Live photoactivated localization microscopy shows a similar dopamine transporter membrane organization in live heterologous cells. In neurons, dual-color dSTORM shows that tyrosine hydroxylase and vesicular monoamine transporter-2 are distinctively localized adjacent to...

  16. Total protein and cholesterol concentrations in brain regions of male ...

    African Journals Online (AJOL)

    The results showed similarities (P>0.05) between the treatments in total protein concentrations in the cerebral cortex, medulla, hypothalamus, amygdala, mesencephalon and hippocampus. Total protein concentrations however differed significantly between diets (P<0.05) in the cerebellum and pons varoli with the lowest ...

  17. Cholesterol Transporters ABCA1 and ABCG1 Gene Expression in Peripheral Blood Mononuclear Cells in Patients with Metabolic Syndrome

    Directory of Open Access Journals (Sweden)

    Zahra Tavoosi

    2015-01-01

    Full Text Available ABCA1 and ABCG1 genes encode the cholesterol transporter proteins that play a key role in cholesterol and phospholipids homeostasis. This study was aimed at evaluating and comparing ABCA1 and ABCG1 genes expression in metabolic syndrome patients and healthy individuals. This case-control study was performed on 36 patients with metabolic syndrome and the same number of healthy individuals in Hamadan (west of Iran during 2013-2014. Total RNA was extracted from mononuclear cells and purified using RNeasy Mini Kit column. The expression of ABCA1 and ABCG1 genes was performed by qRT-PCR. Lipid profile and fasting blood glucose were measured using colorimetric procedures. ABCG1 expression in metabolic syndrome patients was significantly lower (about 75% compared to that of control group, while for ABCA1 expression, there was no significant difference between the two studied groups. Comparison of other parameters such as HDL-C, FBS, BMI, waist circumference, and systolic and diastolic blood pressure between metabolic syndrome patients and healthy individuals showed significant differences (P<0.05. Decrease in ABCG1 expression in metabolic syndrome patients compared to healthy individuals suggests that hyperglycemia, related metabolites, and hyperlipidemia over the transporter capacity resulted in decreased expression of ABCG1. Absence of a significant change in ABCA1 gene expression between two groups can indicate a different regulation mechanism for ABCA1 expression.

  18. Effect of DOPE and cholesterol on the protein adsorption onto lipid nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Caracciolo, Giulio, E-mail: giulio.caracciolo@uniroma1.it; Pozzi, Daniela [' Sapienza' University of Rome, Department of Molecular Medicine (Italy); Capriotti, Anna Laura; Cavaliere, Chiara; Lagana, Aldo [' Sapienza' University of Rome, Department of Chemistry (Italy)

    2013-03-15

    Upon administration, nanoparticles (NPs) are exposed to biological fluids from which they adsorb proteins and other biomolecules to form a 'protein corona'. NP-protein interactions are still poorly understood and quantitative studies to characterize them remain scarce. Here, we have investigated the effect of neutral dioleoylphosphatidylethanolamine (DOPE) and cholesterol on the adsorption of human plasma proteins onto the surface of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based cationic liposomes of 100 nm in diameter. Quantitative analysis of the protein corona revealed that replacing cationic DOTAP lipids with neutral lipids, being indifferently DOPE or cholesterol, reduces the affinity of fibrinogen, prothrombin, vitamin K, and vitronectin for the lipid surface. On the other side, DOPE specifically promotes the adsorption of apolipoproteins and serum albumin, while cholesterol induces the preferential binding of immunoglobulins and complement proteins. The results of this study will help to explain why NPs of different lipid compositions have a dramatic difference in their in vivo transfection efficiency and will be useful for design of lipid NPs with optimal circulation profiles.

  19. Effect of DOPE and cholesterol on the protein adsorption onto lipid nanoparticles

    International Nuclear Information System (INIS)

    Caracciolo, Giulio; Pozzi, Daniela; Capriotti, Anna Laura; Cavaliere, Chiara; Laganà, Aldo

    2013-01-01

    Upon administration, nanoparticles (NPs) are exposed to biological fluids from which they adsorb proteins and other biomolecules to form a “protein corona”. NP–protein interactions are still poorly understood and quantitative studies to characterize them remain scarce. Here, we have investigated the effect of neutral dioleoylphosphatidylethanolamine (DOPE) and cholesterol on the adsorption of human plasma proteins onto the surface of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based cationic liposomes of 100 nm in diameter. Quantitative analysis of the protein corona revealed that replacing cationic DOTAP lipids with neutral lipids, being indifferently DOPE or cholesterol, reduces the affinity of fibrinogen, prothrombin, vitamin K, and vitronectin for the lipid surface. On the other side, DOPE specifically promotes the adsorption of apolipoproteins and serum albumin, while cholesterol induces the preferential binding of immunoglobulins and complement proteins. The results of this study will help to explain why NPs of different lipid compositions have a dramatic difference in their in vivo transfection efficiency and will be useful for design of lipid NPs with optimal circulation profiles.

  20. Insig proteins mediate feedback inhibition of cholesterol synthesis in the intestine.

    Science.gov (United States)

    McFarlane, Matthew R; Liang, Guosheng; Engelking, Luke J

    2014-01-24

    Enterocytes are the only cell type that must balance the de novo synthesis and absorption of cholesterol, although the coordinate regulation of these processes is not well understood. Our previous studies demonstrated that enterocytes respond to the pharmacological blockade of cholesterol absorption by ramping up de novo sterol synthesis through activation of sterol regulatory element-binding protein-2 (SREBP-2). Here, we genetically disrupt both Insig1 and Insig2 in the intestine, two closely related proteins that are required for the feedback inhibition of SREBP and HMG-CoA reductase (HMGR). This double knock-out was achieved by generating mice with an intestine-specific deletion of Insig1 using Villin-Cre in combination with a germ line deletion of Insig2. Deficiency of both Insigs in enterocytes resulted in constitutive activation of SREBP and HMGR, leading to an 11-fold increase in sterol synthesis in the small intestine and producing lipidosis of the intestinal crypts. The intestine-derived cholesterol accumulated in plasma and liver, leading to secondary feedback inhibition of hepatic SREBP2 activity. Pharmacological blockade of cholesterol absorption was unable to further induce the already elevated activities of SREBP-2 or HMGR in Insig-deficient enterocytes. These studies confirm the essential role of Insig proteins in the sterol homeostasis of enterocytes.

  1. Insig Proteins Mediate Feedback Inhibition of Cholesterol Synthesis in the Intestine*

    Science.gov (United States)

    McFarlane, Matthew R.; Liang, Guosheng; Engelking, Luke J.

    2014-01-01

    Enterocytes are the only cell type that must balance the de novo synthesis and absorption of cholesterol, although the coordinate regulation of these processes is not well understood. Our previous studies demonstrated that enterocytes respond to the pharmacological blockade of cholesterol absorption by ramping up de novo sterol synthesis through activation of sterol regulatory element-binding protein-2 (SREBP-2). Here, we genetically disrupt both Insig1 and Insig2 in the intestine, two closely related proteins that are required for the feedback inhibition of SREBP and HMG-CoA reductase (HMGR). This double knock-out was achieved by generating mice with an intestine-specific deletion of Insig1 using Villin-Cre in combination with a germ line deletion of Insig2. Deficiency of both Insigs in enterocytes resulted in constitutive activation of SREBP and HMGR, leading to an 11-fold increase in sterol synthesis in the small intestine and producing lipidosis of the intestinal crypts. The intestine-derived cholesterol accumulated in plasma and liver, leading to secondary feedback inhibition of hepatic SREBP2 activity. Pharmacological blockade of cholesterol absorption was unable to further induce the already elevated activities of SREBP-2 or HMGR in Insig-deficient enterocytes. These studies confirm the essential role of Insig proteins in the sterol homeostasis of enterocytes. PMID:24337570

  2. Transintestinal transport of the anti-inflammatory drug 4F and the modulation of transintestinal cholesterol efflux[S

    Science.gov (United States)

    Meriwether, David; Sulaiman, Dawoud; Wagner, Alan; Grijalva, Victor; Kaji, Izumi; Williams, Kevin J.; Yu, Liqing; Fogelman, Spencer; Volpe, Carmen; Bensinger, Steven J.; Anantharamaiah, G. M.; Shechter, Ishaiahu; Fogelman, Alan M.; Reddy, Srinivasa T.

    2016-01-01

    The site and mechanism of action of the apoA-I mimetic peptide 4F are incompletely understood. Transintestinal cholesterol efflux (TICE) is a process involved in the clearance of excess cholesterol from the body. While TICE is responsible for at least 30% of the clearance of neutral sterols from the circulation into the intestinal lumen, few pharmacological agents have been identified that modulate this pathway. We show first that circulating 4F selectively targets the small intestine (SI) and that it is predominantly transported into the intestinal lumen. This transport of 4F into the SI lumen is transintestinal in nature, and it is modulated by TICE. We also show that circulating 4F increases reverse cholesterol transport from macrophages and cholesterol efflux from lipoproteins via the TICE pathway. We identify the cause of this modulation of TICE either as 4F being a cholesterol acceptor with respect to enterocytes, from which 4F enhances cholesterol efflux, or as 4F being an intestinal chaperone with respect to TICE. Our results assign a novel role for 4F as a modulator of the TICE pathway and suggest that the anti-inflammatory functions of 4F may be a partial consequence of the codependent intestinal transport of both 4F and cholesterol. PMID:27199144

  3. Chronic vitamin A-enriched diet feeding regulates hypercholesterolaemia through transcriptional regulation of reverse cholesterol transport pathway genes in obese rat model of WNIN/GR-Ob strain

    Directory of Open Access Journals (Sweden)

    Shanmugam M Jeyakumar

    2016-01-01

    Full Text Available Background & objectives: Hepatic scavenger receptor class B1 (SR-B1, a high-density lipoprotein (HDL receptor, is involved in the selective uptake of HDL-associated esterified cholesterol (EC, thereby regulates cholesterol homoeostasis and improves reverse cholesterol transport. Previously, we reported in euglycaemic obese rats (WNIN/Ob strain that feeding of vitamin A-enriched diet normalized hypercholesterolaemia, possibly through hepatic SR-B1-mediated pathway. This study was aimed to test whether it would be possible to normalize hypercholesterolaemia in glucose-intolerant obese rat model (WNIN/GR/Ob through similar mechanism by feeding identical vitamin A-enriched diet. Methods: In this study, 30 wk old male lean and obese rats of WNIN/GR-Ob strain were divided into two groups and received either stock diet or vitamin A-enriched diet (2.6 mg or 129 mg vitamin A/kg diet for 14 wk. Blood and other tissues were collected for various biochemical analyses. Results: Chronic vitamin A-enriched diet feeding decreased hypercholesterolaemia and normalized abnormally elevated plasma HDL-cholesterol (HDL-C levels in obese rats as compared to stock diet-fed obese groups. Further, decreased free cholesterol (FC and increased esterified cholesterol (EC contents of plasma cholesterol were observed, which were reflected in higher EC to FC ratio of vitamin A-enriched diet-fed obese rats. However, neither lecithin-cholesterol acyltransferase (LCAT activity of plasma nor its expression (both gene and protein in the liver were altered. On the contrary, hepatic cholesterol levels significantly increased in vitamin A-enriched diet fed obese rats. Hepatic SR-B1 expression (both mRNA and protein remained unaltered among groups. Vitamin A-enriched diet fed obese rats showed a significant increase in hepatic low-density lipoprotein receptor mRNA levels, while the expression of genes involved in HDL synthesis, namely, ATP-binding cassette protein 1 (ABCA1 and

  4. Cholesterol regulates the endoplasmic reticulum exit of the major membrane protein P0 required for peripheral myelin compaction.

    Science.gov (United States)

    Saher, Gesine; Quintes, Susanne; Möbius, Wiebke; Wehr, Michael C; Krämer-Albers, Eva-Maria; Brügger, Britta; Nave, Klaus-Armin

    2009-05-13

    Rapid impulse conduction requires electrical insulation of axons by myelin, a cholesterol-rich extension of the glial cell membrane with a characteristic composition of proteins and lipids. Mutations in several myelin protein genes cause endoplasmic reticulum (ER) retention and disease, presumably attributable to failure of misfolded proteins to pass the ER quality control. Because many myelin proteins partition into cholesterol-rich membrane rafts, their interaction with cholesterol could potentially be part of the ER quality control system. Here, we provide in vitro and in vivo evidence that the major peripheral myelin protein P0 requires cholesterol for exiting the ER and reaching the myelin compartment. Cholesterol dependency of P0 trafficking in heterologous cells is mediated by a cholesterol recognition/interaction amino acid consensus (CRAC) motif. Mutant mice lacking cholesterol biosynthesis in Schwann cells suffer from severe hypomyelination with numerous uncompacted myelin stretches. This demonstrates that high-level cholesterol coordinates P0 export with myelin membrane synthesis, which is required for the correct stoichiometry of myelin components and for myelin compaction.

  5. Effect of the combinations between pea proteins and soluble fibres on cholesterolaemia and cholesterol metabolism in rats.

    Science.gov (United States)

    Parolini, Cinzia; Manzini, Stefano; Busnelli, Marco; Rigamonti, Elena; Marchesi, Marta; Diani, Erika; Sirtori, Cesare R; Chiesa, Giulia

    2013-10-01

    Many functional foods and dietary supplements have been reported to be beneficial for the management of dyslipidaemia, one of the major risk factors for CVD. Soluble fibres and legume proteins are known to be a safe and practical approach for cholesterol reduction. The present study aimed at investigating the hypocholesterolaemic effect of the combinations of these bioactive vegetable ingredients and their possible effects on the expression of genes regulating cholesterol homeostasis. A total of six groups of twelve rats each were fed, for 28 d, Nath's hypercholesterolaemic diets, differing in protein and fibre sources, being, respectively, casein and cellulose (control), pea proteins and cellulose (pea), casein and oat fibres (oat), casein and apple pectin (pectin), pea proteins and oat fibres (pea+oat) and pea proteins and apple pectin (pea+pectin). Administration of each vegetable-containing diet was associated with lower total cholesterol concentrations compared with the control. The combinations (pea+oat and pea+pectin) were more efficacious than fibres alone in modulating cholesterolaemia ( - 53 and - 54%, respectively, at 28 d; Ppea proteins, a lower hepatic cholesterol content (Ppea proteins and oat fibres or apple pectin are extremely effective in lowering plasma cholesterol concentrations in rats and affect cellular cholesterol homeostasis by up-regulating genes involved in hepatic cholesterol turnover.

  6. Tracking cholesterol/sphingomyelin-rich membrane domains with the ostreolysin A-mCherry protein.

    Directory of Open Access Journals (Sweden)

    Matej Skočaj

    Full Text Available Ostreolysin A (OlyA is an ∼15-kDa protein that has been shown to bind selectively to membranes rich in cholesterol and sphingomyelin. In this study, we investigated whether OlyA fluorescently tagged at the C-terminal with mCherry (OlyA-mCherry labels cholesterol/sphingomyelin domains in artificial membrane systems and in membranes of Madin-Darby canine kidney (MDCK epithelial cells. OlyA-mCherry showed similar lipid binding characteristics to non-tagged OlyA. OlyA-mCherry also stained cholesterol/sphingomyelin domains in the plasma membranes of both fixed and living MDCK cells, and in the living cells, this staining was abolished by pretreatment with either methyl-β-cyclodextrin or sphingomyelinase. Double labelling of MDCK cells with OlyA-mCherry and the sphingomyelin-specific markers equinatoxin II-Alexa488 and GST-lysenin, the cholera toxin B subunit as a probe that binds to the ganglioside GM1, or the cholesterol-specific D4 domain of perfringolysin O fused with EGFP, showed different patterns of binding and distribution of OlyA-mCherry in comparison with these other proteins. Furthermore, we show that OlyA-mCherry is internalised in living MDCK cells, and within 90 min it reaches the juxtanuclear region via caveolin-1-positive structures. No binding to membranes could be seen when OlyA-mCherry was expressed in MDCK cells. Altogether, these data clearly indicate that OlyA-mCherry is a promising tool for labelling a distinct pool of cholesterol/sphingomyelin membrane domains in living and fixed cells, and for following these domains when they are apparently internalised by the cell.

  7. Cholesterol transfer at endosomal-organelle membrane contact sites.

    Science.gov (United States)

    Ridgway, Neale D; Zhao, Kexin

    2018-06-01

    Cholesterol is delivered to the limiting membrane of late endosomes by Niemann-Pick Type C1 and C2 proteins. This review summarizes recent evidence that cholesterol transfer from endosomes to the endoplasmic reticulum and other organelles is mediated by lipid-binding proteins that localize to membrane contact sites (MCS). LDL-cholesterol in the late endosomal/lysosomes is exported to the plasma membrane, where most cholesterol resides, and the endoplasmic reticulum, which harbors the regulatory complexes and enzymes that control the synthesis and esterification of cholesterol. A major advance in dissecting these cholesterol transport pathways was identification of frequent and dynamic MCS between endosomes and the endoplasmic reticulum, peroxisomes and plasma membrane. Positioned at these MCS are members of the oxysterol-binding protein (OSBP) and steroidogenic acute regulatory protein-related lipid-transfer family of lipid transfer proteins that bridge the opposing membranes and directly or indirectly mediate cholesterol transfer. OSBP-related protein 1L (ORP1L), ORP5 and ORP6 mediate cholesterol transfer to the endoplasmic reticulum that regulates cholesterol homeostasis. ORP1L and STARD3 also move cholesterol from the endoplasmic reticulum-to-late endosomal/lysosomes under low-cholesterol conditions to facilitate intraluminal vesicle formation. Cholesterol transport also occurs at MCS with peroxisomes and possibly the plasma membrane. Frequent contacts between organelles and the endo-lysosomal vesicles are sites for bidirectional transfer of cholesterol.

  8. Transporter taxonomy - a comparison of different transport protein classification schemes.

    Science.gov (United States)

    Viereck, Michael; Gaulton, Anna; Digles, Daniela; Ecker, Gerhard F

    2014-06-01

    Currently, there are more than 800 well characterized human membrane transport proteins (including channels and transporters) and there are estimates that about 10% (approx. 2000) of all human genes are related to transport. Membrane transport proteins are of interest as potential drug targets, for drug delivery, and as a cause of side effects and drug–drug interactions. In light of the development of Open PHACTS, which provides an open pharmacological space, we analyzed selected membrane transport protein classification schemes (Transporter Classification Database, ChEMBL, IUPHAR/BPS Guide to Pharmacology, and Gene Ontology) for their ability to serve as a basis for pharmacology driven protein classification. A comparison of these membrane transport protein classification schemes by using a set of clinically relevant transporters as use-case reveals the strengths and weaknesses of the different taxonomy approaches.

  9. Medium-chain triglycerides promote macrophage reverse cholesterol transport and improve atherosclerosis in ApoE-deficient mice fed a high-fat diet.

    Science.gov (United States)

    Zhang, Xinsheng; Zhang, Yong; Liu, Yinghua; Wang, Jin; Xu, Qing; Yu, Xiaoming; Yang, Xueyan; Liu, Zhao; Xue, Changyong

    2016-09-01

    We previously observed that medium-chain triglycerides (MCTs) could reduce body fat mass and improve the metabolism of cholesterol. We hypothesized that MCTs can improve atherosclerosis by promoting the reverse cholesterol transport (RCT) process. Therefore, the objective of this study was to investigate the roles of MCTs in macrophage RCT and the progression of atherosclerosis. To test this hypothesis, 30 4-week-old ApoE-deficient (ApoE(-/-)) mice were randomly divided into 2 groups and fed a diet of 2% MCTs or long-chain triglycerides (LCTs) for 16 weeks. Ten age- and sex-matched C57BL/6J mice were fed a diet of 2% LCTs as the control. Macrophage-to-feces RCT was assessed in vivo by intraperitoneal injection of RAW 264.7 macrophages containing (3)H-labeled cholesterol, and atherosclerotic plaques were measured. The mRNA and protein expressions were determined by reverse transcriptase polymerase chain reaction and Western blot analyses, respectively. There was a greater decrease in body fat mass, atherosclerotic plaques, and an improvement in serum lipid profiles. In addition, the MCT mice group showed an increase in (3)H-tracer in the feces and a decrease in the liver. Significantly higher levels of mRNA and protein expression of hepatic ATP-binding cassette transporter A1, ATP-binding cassette transporter G5, cholesterol 7α-hydroxylase, and intestinal ATP-binding cassette transporter G8, as well as lower levels of expression of intestinal Niemann-Pick C1-like 1, were found in the MCT group. These results suggest that MCTs could obviously promote macrophage RCT and improve atherosclerosis in ApoE(-/-) mice, indicating that MCTs have the potential to prevent cardiovascular disease. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Effect of sardine proteins on hyperglycaemia, hyperlipidaemia and lecithin:cholesterol acyltransferase activity, in high-fat diet-induced type 2 diabetic rats.

    Science.gov (United States)

    Benaicheta, Nora; Labbaci, Fatima Z; Bouchenak, Malika; Boukortt, Farida O

    2016-01-14

    Type 2 diabetes (T2D) is a major risk factor of CVD. The effects of purified sardine proteins (SP) were examined on glycaemia, insulin sensitivity and reverse cholesterol transport in T2D rats. Rats fed a high-fat diet (HFD) for 5 weeks, and injected with a low dose of streptozotocin, were used. The diabetic rats were divided into four groups, and they were fed casein (CAS) or SP combined with 30 or 5% lipids, for 4 weeks. HFD-induced hyperglycaemia, insulin resistance and hyperlipidaemia in rats fed HFD, regardless of the consumed protein. In contrast, these parameters lowered in rats fed SP combined with 5 or 30% lipids, and serum insulin values reduced in SP v. CAS. HFD significantly increased total cholesterol and TAG concentrations in the liver and serum, whereas these parameters decreased with SP, regardless of lipid intake. Faecal cholesterol excretion was higher with SP v. CAS, combined with 30 or 5% lipids. Lecithin:cholesterol acyltransferase (LCAT) activity and HDL3-phospholipids (PL) were higher in CAS-HF than in CAS, whereas HDL2-cholesteryl esters (CE) were lower. Otherwise, LCAT activity and HDL2-CE were higher in the SP group than in the CAS group, whereas HDL3-PL and HDL3-unesterified cholesterol were lower. Moreover, LCAT activity lowered in the SP-HF group than in the CAS-HF group, when HDL2-CE was higher. In conclusion, these results indicate the potential effects of SP to improve glycaemia, insulin sensitivity and reverse cholesterol transport, in T2D rats.

  11. In Vitro Analysis of Metabolite Transport Proteins.

    Science.gov (United States)

    Roell, Marc-Sven; Kuhnert, Franziska; Zamani-Nour, Shirin; Weber, Andreas P M

    2017-01-01

    The photorespiratory cycle is distributed over four cellular compartments, the chloroplast, peroxisomes, cytoplasm, and mitochondria. Shuttling of photorespiratory intermediates between these compartments is essential to maintain the function of photorespiration. Specific transport proteins mediate the transport across biological membranes and represent important components of the cellular metabolism. Although significant progress was made in the last years on identifying and characterizing new transport proteins, the overall picture of intracellular metabolite transporters is still rather incomplete. The photorespiratory cycle requires at least 25 transmembrane transport steps; however to date only plastidic glycolate/glycerate transporter and the accessory 2-oxoglutarate/malate and glutamate/malate transporters as well as the mitochondrial transporter BOU1 have been identified. The characterization of transport proteins and defining their substrates and kinetics are still major challenges.Here we present a detailed set of protocols for the in vitro characterization of transport proteins. We provide protocols for the isolation of recombinant transport protein expressed in E. coli or Saccharomyces cerevisiae and the extraction of total leaf membrane protein for in vitro analysis of transporter proteins. Further we explain the process of reconstituting transport proteins in artificial lipid vesicles and elucidate the details of transport assays.

  12. Mevinolin-induced changes in cholesterol synthesis and protein glycosylation in lymphocytes of hypercholesterolemics

    International Nuclear Information System (INIS)

    Goel, V.; Premkumar, N.D.; Ramachandran, C.K.; Melnykovych, G.; Dujovne, C.A.

    1987-01-01

    Mevinolin (lovastatin, MVN), a potent competitive inhibitor of HMG CoA reductase (HMGR), has proven to be an effective hypolipidemic agent in patients with non-homozygous primary hypercholesterolemia. Since inhibition of HMGR can also reduce the synthesis of non-sterol mevalonate products such as dolichols, it was of interest to examine the dolichol-mediated cellular reactions in MVN-treated patients. Blood was collected from patients after various durations of MVN therapy. Peripheral lymphocytes were isolated using Ficoll-Paque gradient. The cells were suspended in RPMI-1640 medium and pulsed in the presence of 14 C-2-acetate or 3 H-mannose for 30 min. At the end of incubation the radioactivity recovered in non-saponifiable fraction ( 14 C) or TCA precipitable protein ( 3 H) was measured. Cholesterol synthesis continued to fall gradually and remained low throughout, in direct correlation with falls in plasma LDL cholesterol levels. Incorporation of mannose into protein fraction was reduced by the 1st month of therapy, remained low until the 7th month and recovered by the 10th month while on MVN. In summary, MVN appears to reduce cholesterol synthesis continuously but its inhibitory effect on glycosylation seems to be overcome after prolonged therapy. This escape effect could result from a rebound increase in HMGR in response to its competitive inhibition by MVN

  13. Plasma lecithin : cholesterol acyltransferase activity modifies the inverse relationship of C-reactive protein with HDL cholesterol in nondiabetic men

    NARCIS (Netherlands)

    Dullaart, R. P. F.; Perton, F.; Kappelle, P.J.W.H.; de Vries, R.; Sluiter, W. J.; van Tol, A.

    Lecithin:cholesterol acyltransferase (LCAT) is instrumental in high-density lipoprotein (HDL) maturation, but high LCAT levels do not predict low cardiovascular risk. LCAT may affect antioxidative or anti-inflammatory properties of HDL We determined the relationship of plasma high-sensitivity

  14. The Impairment of Macrophage-to-Feces Reverse Cholesterol Transport during Inflammation Does Not Depend on Serum Amyloid A.

    Science.gov (United States)

    de Beer, Maria C; Wroblewski, Joanne M; Noffsinger, Victoria P; Ji, Ailing; Meyer, Jason M; van der Westhuyzen, Deneys R; de Beer, Frederick C; Webb, Nancy R

    2013-01-01

    Studies suggest that inflammation impairs reverse cholesterol transport (RCT). We investigated whether serum amyloid A (SAA) contributes to this impairment using an established macrophage-to-feces RCT model. Wild-type (WT) mice and mice deficient in SAA1.1 and SAA2.1 (SAAKO) were injected intraperitoneally with (3)H-cholesterol-labeled J774 macrophages 4 hr after administration of LPS or buffered saline. (3)H-cholesterol in plasma 4 hr after macrophage injection was significantly reduced in both WT and SAAKO mice injected with LPS, but this was not associated with a reduced capacity of serum from LPS-injected mice to promote macrophage cholesterol efflux in vitro. Hepatic accumulation of (3)H-cholesterol was unaltered in either WT or SAAKO mice by LPS treatment. Radioactivity present in bile and feces of LPS-injected WT mice 24 hr after macrophage injection was reduced by 36% (P < 0.05) and 80% (P < 0.001), respectively. In contrast, in SAAKO mice, LPS did not significantly reduce macrophage-derived (3)H-cholesterol in bile, and fecal excretion was reduced by only 45% (P < 0.05). Injection of cholesterol-loaded allogeneic J774 cells, but not syngeneic bone-marrow-derived macrophages, transiently induced SAA in C57BL/6 mice. Our study confirms reports that acute inflammation impairs steps in the RCT pathway and establishes that SAA plays only a minor role in this impairment.

  15. Cholesterol up-regulates neuronal G protein-gated inwardly rectifying potassium (GIRK) channel activity in the hippocampus.

    Science.gov (United States)

    Bukiya, Anna N; Durdagi, Serdar; Noskov, Sergei; Rosenhouse-Dantsker, Avia

    2017-04-14

    Hypercholesterolemia is a well known risk factor for the development of neurodegenerative disease. However, the underlying mechanisms are mostly unknown. In recent years, it has become increasingly evident that cholesterol-driven effects on physiology and pathophysiology derive from its ability to alter the function of a variety of membrane proteins including ion channels. Yet, the effect of cholesterol on G protein-gated inwardly rectifying potassium (GIRK) channels expressed in the brain is unknown. GIRK channels mediate the actions of inhibitory brain neurotransmitters. As a result, loss of GIRK function can enhance neuron excitability, whereas gain of GIRK function can reduce neuronal activity. Here we show that in rats on a high-cholesterol diet, cholesterol levels in hippocampal neurons are increased. We also demonstrate that cholesterol plays a critical role in modulating neuronal GIRK currents. Specifically, cholesterol enrichment of rat hippocampal neurons resulted in enhanced channel activity. In accordance, elevated currents upon cholesterol enrichment were also observed in Xenopus oocytes expressing GIRK2 channels, the primary GIRK subunit expressed in the brain. Furthermore, using planar lipid bilayers, we show that although cholesterol did not affect the unitary conductance of GIRK2, it significantly enhanced the frequency of channel openings. Last, combining computational and functional approaches, we identified two putative cholesterol-binding sites in the transmembrane domain of GIRK2. These findings establish that cholesterol plays a critical role in modulating GIRK activity in the brain. Because up-regulation of GIRK function can reduce neuronal activity, our findings may lead to novel approaches for prevention and therapy of cholesterol-driven neurodegenerative disease. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Genetic variation in ABC transporter A1 contributes to HDL cholesterol in the general population

    DEFF Research Database (Denmark)

    Frikke-Schmidt, Ruth; Nordestgaard, Børge G; Jensen, Gorm B

    2004-01-01

    Homozygosity for mutations in ABC transporter A1 (ABCA1) causes Tangier disease, a rare HDL-deficiency syndrome. Whether heterozygosity for genetic variation in ABCA1 also contributes to HDL cholesterol (HDL-C) levels in the general population is presently unclear. We determined whether mutations...... or single-nucleotide polymorphisms (SNPs) in ABCA1 were overrepresented in individuals with the lowest 1% (n=95) or highest 1% (n=95) HDL-C levels in the general population by screening the core promoter and coding region of ABCA1. For all nonsynonymous SNPs identified, we determined the effect of genotype...... on lipid traits in 9,259 individuals from the general population. Heterozygosity for ABCA1 mutations was identified in 10% of individuals with low HDL-C only. Three of 6 nonsynonymous SNPs (V771M, V825I, and R1587K) were associated with increases or decreases in HDL-C in women in the general population...

  17. IMB2026791, a Xanthone, Stimulates Cholesterol Efflux by Increasing the Binding of Apolipoprotein A-I to ATP-Binding Cassette Transporter A1

    Directory of Open Access Journals (Sweden)

    Zijian Xie

    2012-03-01

    Full Text Available It is known that the ATP-binding cassette transporter A1 (ABCA1 plays a major role in cholesterol homeostasis and high density lipoprotein (HDL metabolism. Several laboratories have demonstrated that ABCA1 binding to lipid-poor apolipoprotein A-I (apoA-I will mediate the assembly of nascent HDL and cellular cholesterol efflux, which suggests a possible receptor-ligand interaction between ABCA1 and apoA-I. In this study, a cell-based-ELISA-like high-throughput screening (HTS method was developed to identify the synthetic and natural compounds that can regulate binding activity of ABCA1 to apoA-I. The cell-based-ELISA-like high-throughput screen was conducted in a 96-well format using Chinese hamster ovary (CHO cells stably transfected with ABCA1 pIRE2-EGFP (Enhanced Green Fluorecence Protein expression vector and the known ABCA1 inhibitor glibenclamide as the antagonist control. From 2,600 compounds, a xanthone compound (IMB 2026791 was selected using this HTS assay, and it was proved as an apoA-I binding agonist to ABCA1 by a flow cytometry assay and western blot analysis. The [3H] cholesterol efflux assay of IMB2026791 treated ABCA1-CHO cells and PMA induced THP-1 macrophages (human acute monocytic leukemia cell further confirmed the compound as an accelerator of cholesterol efflux in a dose-dependent manner with an EC50 of 25.23 μM.

  18. The Role of Maternal-Fetal Cholesterol Transport in Early Fetal Life : Current Insights

    NARCIS (Netherlands)

    Baardman, Maria E.; Kerstjens-Frederikse, Wilhelmina S.; Berger, Rolf M. F.; Bakker, Marian K.; Hofstra, Robert M. W.; Plosch, Torsten

    The importance of maternal cholesterol as an exogenous cholesterol source for the growing embryo was first reported in studies of Smith-Lemli-Opitz syndrome. Although most of the fetus's cholesterol is synthesized by the fetus itself, there is now growing evidence that during the first weeks of

  19. The role of maternal-fetal cholesterol transport in early fetal life: Current insights

    NARCIS (Netherlands)

    T. Baardman (Taco); W.S. Kerstjens-Frederikse (Wilhelmina); R.M.F. Berger (Rolf); M.K. Bakker (Marian); R.M.W. Hofstra (Robert); T. Plösch (Torsten)

    2013-01-01

    textabstractThe importance of maternal cholesterol as an exogenous cholesterol source for the growing embryo was first reported in studies of Smith-Lemli-Opitz syndrome. Although most of the fetus's cholesterol is synthesized by the fetus itself, there is now growing evidence that during the first

  20. Na,K-ATPase reconstituted in ternary liposome: the presence of cholesterol affects protein activity and thermal stability.

    Science.gov (United States)

    Yoneda, Juliana Sakamoto; Rigos, Carolina Fortes; de Lourenço, Thaís Fernanda Aranda; Sebinelli, Heitor Gobbi; Ciancaglini, Pietro

    2014-12-15

    Differential scanning calorimetry (DSC) was applied to investigate the effect of cholesterol on the thermotropic properties of the lipid membrane (DPPC and DPPE). The thermostability and unfolding of solubilized and reconstituted Na,K-ATPase in DPPC:DPPE:cholesterol-liposomes was also studied to gain insight into the role of cholesterol in the Na,K-ATPase modulation of enzyme function and activity. The tertiary system (DPPC:DPPE:cholesterol) (molar ratio DPPC:DPPE equal 1:1) when cholesterol content was increased from 0% up to 40% results in a slight decrease in the temperature of transition and enthalpy, and an increase in width. We observed that, without heating treatment, at 37°C, the activity was higher for 20mol% cholesterol. However, thermal inactivation experiments showed that the enzyme activity loss time depends on the cholesterol membrane content. The unfolding of the enzyme incorporated to liposomes of DPPC:DPPE (1:1mol) with different cholesterol contents, ranging from 0% to 40% mol was also studied by DSC. Some differences between the thermograms indicate that the presence of lipids promotes a conformational change in protein structure and this change is enough to change the way Na,K-ATPase thermally unfolds. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Inhibition of protein kinase C affects on mode of synaptic vesicle exocytosis due to cholesterol depletion

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Alexey M., E-mail: fysio@rambler.ru; Zakyrjanova, Guzalija F., E-mail: guzik121192@mail.ru; Yakovleva, Anastasia A., E-mail: nastya1234qwer@mail.ru; Zefirov, Andrei L., E-mail: zefiroval@rambler.ru

    2015-01-02

    Highlights: • We examine the involvement of PKC in MCD induced synaptic vesicle exocytosis. • PKC inhibitor does not decrease the effect MCD on MEPP frequency. • PKC inhibitor prevents MCD induced FM1-43 unloading. • PKC activation may switch MCD induced exocytosis from kiss-and-run to a full mode. • Inhibition of phospholipase C does not lead to similar change in exocytosis. - Abstract: Previous studies demonstrated that depletion of membrane cholesterol by 10 mM methyl-beta-cyclodextrin (MCD) results in increased spontaneous exocytosis at both peripheral and central synapses. Here, we investigated the role of protein kinase C in the enhancement of spontaneous exocytosis at frog motor nerve terminals after cholesterol depletion using electrophysiological and optical methods. Inhibition of the protein kinase C by myristoylated peptide and chelerythrine chloride prevented MCD-induced increases in FM1-43 unloading, whereas the frequency of spontaneous postsynaptic events remained enhanced. The increase in FM1-43 unloading still could be observed if sulforhodamine 101 (the water soluble FM1-43 quencher that can pass through the fusion pore) was added to the extracellular solution. This suggests a possibility that exocytosis of synaptic vesicles under these conditions could occur through the kiss-and-run mechanism with the formation of a transient fusion pore. Inhibition of phospholipase C did not lead to similar change in MCD-induced exocytosis.

  2. Synthesis and live-cell imaging of fluorescent sterols for analysis of intracellular cholesterol transport

    DEFF Research Database (Denmark)

    Modzel, Maciej; Lund, Frederik W.; Wüstner, Daniel

    2017-01-01

    Cellular cholesterol homeostasis relies on precise control of the sterol content of organelle membranes. Obtaining insight into cholesterol trafficking pathways and kinetics by live-cell imaging relies on two conditions. First, one needs to develop suitable analogs that resemble cholesterol...... as closely as possible with respect to their biophysical and biochemical properties. Second, the cholesterol analogs should have good fluorescence properties. This interferes, however, often with the first requirement, such that the imaging instrumentation must be optimized to collect photons from suboptimal...... fluorophores, but good cholesterol mimics, such as the intrinsically fluorescent sterols, cholestatrienol (CTL) or dehydroergosterol (DHE). CTL differs from cholesterol only in having two additional double bonds in the ring system, which is why it is slightly fluorescent in the ultraviolet (UV). In the first...

  3. Cholesterol Corrects Altered Conformation of MHC-II Protein in Leishmania donovani Infected Macrophages: Implication in Therapy

    Science.gov (United States)

    Chakrabarti, Saikat; Roy, Syamal

    2016-01-01

    Background Previously we reported that Kala-azar patients show progressive decrease in serum cholesterol as a function of splenic parasite burden. Splenic macrophages (MΦ) of Leishmania donovani (LD) infected mice show decrease in membrane cholesterol, while LD infected macrophages (I-MΦ) show defective T cell stimulating ability that could be corrected by liposomal delivery of cholesterol. T helper cells recognize peptide antigen in the context of class II MHC molecule. It is known that the conformation of a large number of membrane proteins is dependent on membrane cholesterol. In this investigation we tried to understand the influence of decreased membrane cholesterol in I-MΦ on the conformation of MHC-II protein and peptide-MHC-II stability, and its bearing on the antigen specific T-cell activation. Methodology/Principal Findings MΦ of CBA/j mice were infected with Leishmania donovani (I-MΦ). Two different anti-Aκ mAbs were used to monitor the status of MHC-II protein under parasitized condition. One of them (11.5–2) was conformation specific, whereas the other one (10.2.16) was not. Under parasitized condition, the binding of 11.5–2 decreased significantly with respect to the normal counterpart, whereas that of 10.2.16 remained unaltered. The binding of 11.5–2 was restored to normal upon liposomal delivery of cholesterol in I-MΦ. By molecular dynamics (MD) simulation studies we found that there was considerable conformational fluctuation in the transmembrane domain of the MHC-II protein in the presence of membrane cholesterol than in its absence, which possibly influenced the distal peptide binding groove. This was evident from the faster dissociation of the cognate peptide from peptide-MHC complex under parasitized condition, which could be corrected by liposomal delivery of cholesterol in I-MΦ. Conclusion The decrease in membrane cholesterol in I-MΦ may lead to altered conformation of MHC II, and this may contribute to a faster dissociation of

  4. HDL cholesterol response to GH replacement is associated with common cholesteryl ester transfer protein gene variation (-629C>A) and modified by glucocorticoid treatment

    NARCIS (Netherlands)

    Dullaart, Robin P. F.; van den Berg, Gerrit; van der Knaap, Aafke M.; Dijck-Brouwer, Janneke; Dallinga-Thie, Geesje M.; Zelissen, Peter M. J.; Sluiter, Wim J.; van Beek, André P.

    2010-01-01

    GH replacement lowers total cholesterol and low-density lipoprotein cholesterol (LDL-C) in GH-deficient adults, but effects on high-density lipoprotein (HDL) cholesterol (HDL-C) are variable. Both GH and glucocorticoids decrease cholesteryl ester transfer protein (CETP) activity, which is important

  5. Water Transport Mediated by Other Membrane Proteins.

    Science.gov (United States)

    Huang, Boyue; Wang, Hongkai; Yang, Baoxue

    2017-01-01

    Water transport through membrane is so intricate that there are still some debates. (Aquaporins) AQPs are entirely accepted to allow water transmembrane movement depending on osmotic gradient. Cotransporters and uniporters , however, are also concerned in water homeotatsis. Urea transporter B (UT-B) has a single-channel water permeability that is similar to AQP1. Cystic fibrosis transmembrane conductance regulator (CFTR ) was initially thought as a water channel but now not believed to transport water directly. By cotranporters, water is transported by water osmosis coupling with substrates, which explains how water is transported across the isolated small intestine. This chapter provides information about water transport mediated by other membrane proteins except AQPs .

  6. The Impairment of Macrophage-to-Feces Reverse Cholesterol Transport during Inflammation Does Not Depend on Serum Amyloid A

    Directory of Open Access Journals (Sweden)

    Maria C. de Beer

    2013-01-01

    Full Text Available Studies suggest that inflammation impairs reverse cholesterol transport (RCT. We investigated whether serum amyloid A (SAA contributes to this impairment using an established macrophage-to-feces RCT model. Wild-type (WT mice and mice deficient in SAA1.1 and SAA2.1 (SAAKO were injected intraperitoneally with 3H-cholesterol-labeled J774 macrophages 4 hr after administration of LPS or buffered saline. 3H-cholesterol in plasma 4 hr after macrophage injection was significantly reduced in both WT and SAAKO mice injected with LPS, but this was not associated with a reduced capacity of serum from LPS-injected mice to promote macrophage cholesterol efflux in vitro. Hepatic accumulation of 3H-cholesterol was unaltered in either WT or SAAKO mice by LPS treatment. Radioactivity present in bile and feces of LPS-injected WT mice 24 hr after macrophage injection was reduced by 36%   (P<0.05 and 80%   (P<0.001, respectively. In contrast, in SAAKO mice, LPS did not significantly reduce macrophage-derived 3H-cholesterol in bile, and fecal excretion was reduced by only 45%   (P<0.05. Injection of cholesterol-loaded allogeneic J774 cells, but not syngeneic bone-marrow-derived macrophages, transiently induced SAA in C57BL/6 mice. Our study confirms reports that acute inflammation impairs steps in the RCT pathway and establishes that SAA plays only a minor role in this impairment.

  7. Comparison of serum leptin, glucose, total cholesterol and total protein levels in fertile and repeat breeder cows

    Directory of Open Access Journals (Sweden)

    Saime Guzel

    2014-12-01

    Full Text Available In the present study we measured serum glucose, leptin, total cholesterol and total protein concentrations in repeat breeder cows and compared them with fertile cows. For this aim, 20 repeat breeder cows and 20 fertile cows were used as material. Repeat breeder cows were found to have lower levels of leptin and glucose as compared with fertile ones. No significant differences in total cholesterol and total protein levels were observed between the two groups. No significant correlation of leptin with glucose, total cholesterol and total protein was observed in fertile and repeat breeder cows. Low concentrations of glucose and leptin can have some effects on reproductive problems as repeat breeder and help to understand potential mechanisms impairing fertility in repeat breeder cows.

  8. Consequences of exchanging carbohydrates for proteins in the cholesterol metabolism of mice fed a high-fat diet.

    Directory of Open Access Journals (Sweden)

    Frédéric Raymond

    Full Text Available Consumption of low-carbohydrate, high-protein, high-fat diets lead to rapid weight loss but the cardioprotective effects of these diets have been questioned. We examined the impact of high-protein and high-fat diets on cholesterol metabolism by comparing the plasma cholesterol and the expression of cholesterol biosynthesis genes in the liver of mice fed a high-fat (HF diet that has a high (H or a low (L protein-to-carbohydrate (P/C ratio. H-P/C-HF feeding, compared with L-P/C-HF feeding, decreased plasma total cholesterol and increased HDL cholesterol concentrations at 4-wk. Interestingly, the expression of genes involved in hepatic steroid biosynthesis responded to an increased dietary P/C ratio by first down-regulation (2-d followed by later up-regulation at 4-wk, and the temporal gene expression patterns were connected to the putative activity of SREBF1 and 2. In contrast, Cyp7a1, the gene responsible for the conversion of cholesterol to bile acids, was consistently up-regulated in the H-P/C-HF liver regardless of feeding duration. Over expression of Cyp7a1 after 2-d and 4-wk H-P/C-HF feeding was connected to two unique sets of transcription regulators. At both time points, up-regulation of the Cyp7a1 gene could be explained by enhanced activations and reduced suppressions of multiple transcription regulators. In conclusion, we demonstrated that the hypocholesterolemic effect of H-P/C-HF feeding coincided with orchestrated changes of gene expressions in lipid metabolic pathways in the liver of mice. Based on these results, we hypothesize that the cholesterol lowering effect of high-protein feeding is associated with enhanced bile acid production but clinical validation is warranted. (246 words.

  9. Consequences of exchanging carbohydrates for proteins in the cholesterol metabolism of mice fed a high-fat diet.

    Science.gov (United States)

    Raymond, Frédéric; Wang, Long; Moser, Mireille; Metairon, Sylviane; Mansourian, Robert; Zwahlen, Marie-Camille; Kussmann, Martin; Fuerholz, Andreas; Macé, Katherine; Chou, Chieh Jason

    2012-01-01

    Consumption of low-carbohydrate, high-protein, high-fat diets lead to rapid weight loss but the cardioprotective effects of these diets have been questioned. We examined the impact of high-protein and high-fat diets on cholesterol metabolism by comparing the plasma cholesterol and the expression of cholesterol biosynthesis genes in the liver of mice fed a high-fat (HF) diet that has a high (H) or a low (L) protein-to-carbohydrate (P/C) ratio. H-P/C-HF feeding, compared with L-P/C-HF feeding, decreased plasma total cholesterol and increased HDL cholesterol concentrations at 4-wk. Interestingly, the expression of genes involved in hepatic steroid biosynthesis responded to an increased dietary P/C ratio by first down-regulation (2-d) followed by later up-regulation at 4-wk, and the temporal gene expression patterns were connected to the putative activity of SREBF1 and 2. In contrast, Cyp7a1, the gene responsible for the conversion of cholesterol to bile acids, was consistently up-regulated in the H-P/C-HF liver regardless of feeding duration. Over expression of Cyp7a1 after 2-d and 4-wk H-P/C-HF feeding was connected to two unique sets of transcription regulators. At both time points, up-regulation of the Cyp7a1 gene could be explained by enhanced activations and reduced suppressions of multiple transcription regulators. In conclusion, we demonstrated that the hypocholesterolemic effect of H-P/C-HF feeding coincided with orchestrated changes of gene expressions in lipid metabolic pathways in the liver of mice. Based on these results, we hypothesize that the cholesterol lowering effect of high-protein feeding is associated with enhanced bile acid production but clinical validation is warranted. (246 words).

  10. Functional analysis of candidate ABC transporter proteins for sitosterol transport

    DEFF Research Database (Denmark)

    Albrecht, C; Elliott, J I; Sardini, A

    2002-01-01

    implicated in lipid movement and expressed in tissues with a role in sterol synthesis and absorption, might also be involved in sitosterol transport. Transport by the multidrug resistance P-glycoprotein (P-gp; Abcb1), the multidrug resistance-associated protein (Mrp1; Abcc1), the breast cancer resistance...

  11. Modulation of microRNA Expression in Subjects with Metabolic Syndrome and Decrease of Cholesterol Efflux from Macrophages via microRNA-33-Mediated Attenuation of ATP-Binding Cassette Transporter A1 Expression by Statins.

    Directory of Open Access Journals (Sweden)

    Wei-Ming Chen

    Full Text Available Metabolic syndrome (MetS is a complicated health problem that encompasses a variety of metabolic disorders. In this study, we analyzed the relationship between the major biochemical parameters associated with MetS and circulating levels of microRNA (miR-33, miR-103, and miR-155. We found that miRNA-33 levels were positively correlated with levels of fasting blood glucose, glycosylated hemoglobin A1c, total cholesterol, LDL-cholesterol, and triacylglycerol, but negatively correlated with HDL-cholesterol levels. In the cellular study, miR-33 levels were increased in macrophages treated with high glucose and cholesterol-lowering drugs atorvastatin and pitavastatin. miR-33 has been reported to play an essential role in cholesterol homeostasis through ATP-binding cassette transporter A1 (ABCA1 regulation and reverse cholesterol transport. However, the molecular mechanism underlying the linkage between miR-33 and statin treatment remains unclear. In the present study, we investigated whether atorvastatin and pitavastatin exert their functions through the modulation of miR-33 and ABCA1-mediated cholesterol efflux from macrophages. The results showed that treatment of the statins up-regulated miR-33 expression, but down-regulated ABCA1 mRNA levels in RAW264.7 cells and bone marrow-derived macrophages. Statin-mediated ABCA1 regulation occurs at the post-transcriptional level through targeting of the 3'-UTR of the ABCA1 transcript by miR-33. Additionally, we found significant down-regulation of ABCA1 protein expression in macrophages treated with statins. Finally, we showed that high glucose and statin treatment significantly suppressed cholesterol efflux from macrophages. These findings have highlighted the complexity of statins, which may exert detrimental effects on metabolic abnormalities through regulation of miR-33 target genes.

  12. Modulation of microRNA Expression in Subjects with Metabolic Syndrome and Decrease of Cholesterol Efflux from Macrophages via microRNA-33-Mediated Attenuation of ATP-Binding Cassette Transporter A1 Expression by Statins.

    Science.gov (United States)

    Chen, Wei-Ming; Sheu, Wayne H-H; Tseng, Pei-Chi; Lee, Tzong-Shyuan; Lee, Wen-Jane; Chang, Pey-Jium; Chiang, An-Na

    2016-01-01

    Metabolic syndrome (MetS) is a complicated health problem that encompasses a variety of metabolic disorders. In this study, we analyzed the relationship between the major biochemical parameters associated with MetS and circulating levels of microRNA (miR)-33, miR-103, and miR-155. We found that miRNA-33 levels were positively correlated with levels of fasting blood glucose, glycosylated hemoglobin A1c, total cholesterol, LDL-cholesterol, and triacylglycerol, but negatively correlated with HDL-cholesterol levels. In the cellular study, miR-33 levels were increased in macrophages treated with high glucose and cholesterol-lowering drugs atorvastatin and pitavastatin. miR-33 has been reported to play an essential role in cholesterol homeostasis through ATP-binding cassette transporter A1 (ABCA1) regulation and reverse cholesterol transport. However, the molecular mechanism underlying the linkage between miR-33 and statin treatment remains unclear. In the present study, we investigated whether atorvastatin and pitavastatin exert their functions through the modulation of miR-33 and ABCA1-mediated cholesterol efflux from macrophages. The results showed that treatment of the statins up-regulated miR-33 expression, but down-regulated ABCA1 mRNA levels in RAW264.7 cells and bone marrow-derived macrophages. Statin-mediated ABCA1 regulation occurs at the post-transcriptional level through targeting of the 3'-UTR of the ABCA1 transcript by miR-33. Additionally, we found significant down-regulation of ABCA1 protein expression in macrophages treated with statins. Finally, we showed that high glucose and statin treatment significantly suppressed cholesterol efflux from macrophages. These findings have highlighted the complexity of statins, which may exert detrimental effects on metabolic abnormalities through regulation of miR-33 target genes.

  13. Influence of dietary tender cluster beans (Cyamopsis tetragonoloba) on biliary proteins, bile acid synthesis and cholesterol crystal growth in rat bile.

    Science.gov (United States)

    Raghavendra, Chikkanna K; Srinivasan, Krishnapura

    2015-02-01

    Tender cluster beans (CBs; Cyamopsis tetragonoloba) are observed to possess anti-lithogenic potential in experimental mice. Formation of cholesterol gallstones in gallbladder is controlled by procrystallizing and anticrystallizing factors present in bile in addition to supersaturation of cholesterol. This study aimed at evaluating the influence of CB on biliary glycoproteins, low molecular weight (LMW) and high molecular weight (HMW) proteins, cholesterol nucleation time, and cholesterol crystal growth in rat hepatic bile. Groups of rats were fed for 10 weeks with 0.5% cholesterol to render the bile lithogenic. Experimental dietary interventions were: 10% freeze-dried CB, 1% garlic powder or their combination. Incorporation of CB into HCD decreased the cholesterol saturation index in bile, increased bile flow and biliary glycoproteins. Dietary CB prolonged cholesterol nucleation time in bile. Electrophoresis of biliary proteins showed the presence of high concentration of 27 kDa protein which might be responsible for the prolongation of cholesterol nucleation time in the CB fed group. Proteins of 20 kDa and 18 kDa were higher in CB treated animals, while the same were less expressed in HCD group. Biliary proteins from CB fed animals reduced cholesterol crystal growth index which was elevated in the presence of proteins from HCD group. Cholesterol-7α-hydroxylase and cholesterol-27-hydroxylase mRNA expression was increased in CB treated animals contributing to the bile acid synthesis. Thus, the beneficial anti-lithogenic effect of dietary CB which primarily is due to reduced cholesterol saturation index was additionally affected through a modulation of the nucleating and anti-nucleating proteins that affect cholesterol crystallization. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Phytosterols Differentially Influence ABC transporter Expression, Cholesterol Efflux and Inflammatory Cytokine Secretion in Macrophage Foam Cells

    Science.gov (United States)

    Sabeva, Nadezhda S; McPhaul, Christopher M; Li, Xiangan; Cory, Theodore J.; Feola, David J.; Graf, Gregory A

    2010-01-01

    Phytosterol supplements lower low density lipoprotein (LDL) cholesterol, but accumulate in vascular lesions of patients and limit the anti-atherosclerotic effects of LDL lowering in apolipoprotein E deficient mice, suggesting that the cholesterol lowering benefit of phytosterol supplementation may not be fully realized. Individual phytosterols have cell-type specific effects that may either be beneficial or deleterious with respect to atherosclerosis, but little is known concerning their effects on macrophage function. The effects of phytosterols on ABCA1 and ABCG1 abundance, cholesterol efflux, and inflammatory cytokine secretion were determined in cultured macrophage foam cells. Among the commonly consumed phytosterols, stigmasterol increased expression of ABCA1 and ABCG1 and increased efflux of cholesterol to apolipoprotein (Apo) AI and high density lipoprotein (HDL). Campesterol and sitosterol had no effect on ABCA1 or ABCG1 levels. Sitosterol had no effect of cholesterol efflux to Apo AI or HDL, whereas campesterol had a modest, but significant reduction in cholesterol efflux to HDL in THP-1 macrophages. Whereas stigmasterol blunted aggregated LDL-induced increases in tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β secretion, sitosterol exacerbated these effects. The presence of campesterol had no effect on agLDL-induced inflammatory cytokine secretion from THP-1 macrophages. In conclusion, the presence of stigmasterol in modified lipoproteins promoted cholesterol efflux and suppressed inflammatory cytokine secretion in response to lipid loading in macrophage foam cells. While campesterol was largely inert, the presence of sitosterol increased the proinflammatory cytokine secretion. PMID:21111593

  15. Synergistic activation of G protein-gated inwardly rectifying potassium channels by cholesterol and PI(4,5)P2.

    Science.gov (United States)

    Bukiya, Anna N; Rosenhouse-Dantsker, Avia

    2017-07-01

    G-protein gated inwardly rectifying potassium (GIRK or Kir3) channels play a major role in the control of the heart rate, and require the membrane phospholipid phosphatidylinositol-bis-phosphate (PI(4,5)P 2 ) for activation. Recently, we have shown that the activity of the heterotetrameric Kir3.1/Kir3.4 channel that underlies atrial K ACh currents was enhanced by cholesterol. Similarly, the activities of both the Kir3.4 homomer and its active pore mutant Kir3.4* (Kir3.4_S143T) were also enhanced by cholesterol. Here we employ planar lipid bilayers to investigate the crosstalk between PI(4,5)P 2 and cholesterol, and demonstrate that these two lipids act synergistically to activate Kir3.4* currents. Further studies using the Xenopus oocytes heterologous expression system suggest that PI(4,5)P 2 and cholesterol act via distinct binding sites. Whereas PI(4,5)P 2 binds to the cytosolic domain of the channel, the putative binding region of cholesterol is located at the center of the transmembrane domain overlapping the central glycine hinge region of the channel. Together, our data suggest that changes in the levels of two key membrane lipids - cholesterol and PI(4,5)P 2 - could act in concert to provide fine-tuning of Kir3 channel function. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Interleukin-10 increases reverse cholesterol transport in macrophages through its bidirectional interaction with liver X receptor α

    International Nuclear Information System (INIS)

    Halvorsen, Bente; Holm, Sverre; Yndestad, Arne; Scholz, Hanne; Sagen, Ellen Lund; Nebb, Hilde; Holven, Kirsten B.; Dahl, Tuva B.; Aukrust, Pål

    2014-01-01

    Highlights: • IL-10 promotes reverse cholesterol efflux from lipid loaded macrophages. • IL-10 increases the expression of ABCA-1 and ABCG-1. • IL-10 exhibits cross-talk with the nuclear receptor LXRα. - Abstract: Interleukin (IL)-10 is a prototypical anti-inflammatory cytokine that has been shown to attenuate atherosclerosis development. In addition to its anti-inflammatory properties, the anti-atherogenic effect of IL-10 has recently also been suggested to reflect a complex effect of IL-10 on lipid metabolism in macrophages. In the present study we examined the effects of IL-10 on cholesterol efflux mechanism in lipid-loaded THP-1 macrophages. Our main findings were: (i) IL-10 significantly enhanced cholesterol efflux induced by fetal-calf serum, high-density lipoprotein (HDL) 2 and apolipoprotein A-1. (ii) The IL-10-mediated effects on cholesterol efflux were accompanied by an increased IL-10-mediated expression of the ATP-binding cassette transporters ABCA1 and ABCG1, that was further enhanced when the cells were co-activated with the liver X receptor (LXR)α agonist (22R)-hydroxycholesterol. (iii) The effect of LXRα activation on the IL-10-mediated effects on the ATP-binding cassette transporters seems to include enhancing effects on the IL-10 receptor 1 (IL10R1) expression and interaction with STAT-3 signaling. (iv) These enhancing effects on ABCA1 and ABCG1 was not seen when the cells were stimulated with the IL-10 family members IL-22 and IL-24. This study suggests that the anti-atherogenic properties of IL-10 may include enhancing effects on cholesterol efflux mechanism that involves cross-talk with LXRα activation

  17. Interleukin-10 increases reverse cholesterol transport in macrophages through its bidirectional interaction with liver X receptor α

    Energy Technology Data Exchange (ETDEWEB)

    Halvorsen, Bente, E-mail: Bente.Halvorsen@rr-research.no [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo (Norway); Holm, Sverre [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Yndestad, Arne [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo (Norway); Scholz, Hanne [Section for Transplantation, Institute for Surgical Research, Oslo University Hospital Rikshospitalet, Oslo (Norway); Sagen, Ellen Lund [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Nebb, Hilde [Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); Holven, Kirsten B. [Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Oslo (Norway); Dahl, Tuva B. [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); Aukrust, Pål [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo (Norway)

    2014-08-08

    Highlights: • IL-10 promotes reverse cholesterol efflux from lipid loaded macrophages. • IL-10 increases the expression of ABCA-1 and ABCG-1. • IL-10 exhibits cross-talk with the nuclear receptor LXRα. - Abstract: Interleukin (IL)-10 is a prototypical anti-inflammatory cytokine that has been shown to attenuate atherosclerosis development. In addition to its anti-inflammatory properties, the anti-atherogenic effect of IL-10 has recently also been suggested to reflect a complex effect of IL-10 on lipid metabolism in macrophages. In the present study we examined the effects of IL-10 on cholesterol efflux mechanism in lipid-loaded THP-1 macrophages. Our main findings were: (i) IL-10 significantly enhanced cholesterol efflux induced by fetal-calf serum, high-density lipoprotein (HDL){sub 2} and apolipoprotein A-1. (ii) The IL-10-mediated effects on cholesterol efflux were accompanied by an increased IL-10-mediated expression of the ATP-binding cassette transporters ABCA1 and ABCG1, that was further enhanced when the cells were co-activated with the liver X receptor (LXR)α agonist (22R)-hydroxycholesterol. (iii) The effect of LXRα activation on the IL-10-mediated effects on the ATP-binding cassette transporters seems to include enhancing effects on the IL-10 receptor 1 (IL10R1) expression and interaction with STAT-3 signaling. (iv) These enhancing effects on ABCA1 and ABCG1 was not seen when the cells were stimulated with the IL-10 family members IL-22 and IL-24. This study suggests that the anti-atherogenic properties of IL-10 may include enhancing effects on cholesterol efflux mechanism that involves cross-talk with LXRα activation.

  18. rHDL administration increases reverse cholesterol transport in mice, but is not additive on top of ezetimibe or cholestyramine treatment

    NARCIS (Netherlands)

    Maugeais, Cyrille; Annema, Wijtske; Blum, Denise; Mary, Jean-Luc; Tietge, Uwe J. F.

    Objective: Promoting reverse cholesterol transport (RCT) is a major atheroprotective property of HDL. The present study explored the effect of stimulating the first step of RCT (cholesterol efflux from macrophages) alone or in combination with stimulating the last step of RCT (fecal sterol

  19. Acute and chronic effects of a 24-hour intravenous triglyceride emulsion challenge on plasma lecithin : cholesterol acyltransferase, phospholipid transfer protein, and cholesteryl ester transfer protein activities

    NARCIS (Netherlands)

    Riemens, SC; Van Tol, A; Sluiter, WJ; Dullaart, RPF

    Lecithin:cholesterol acyltransferase (LCAT), phospholipid transfer protein (PLTP), and cholesteryl ester transfer protein (CETP) are key factors in remodeling of high density lipoproteins (HDL) and triglyceride-rich lipoproteins. We examined the effect of a large, 24 h intravenous fat load on plasma

  20. EHD proteins: Key conductors of endocytic transport

    Science.gov (United States)

    Naslavsky, Naava; Caplan, Steve

    2010-01-01

    Regulation of endocytic transport is controlled by an elaborate network of proteins. Rab GTP-binding proteins and their effectors have well-defined roles in mediating specific endocytic transport steps, but until recently, less was known about the four mammalian dynamin-like C-terminal Eps15 Homology Domain (EHD) proteins that also regulate endocytic events. In recent years, however, great strides have been made in understanding the structure and function of these unique proteins. Indeed, a growing body of literature addresses EHD protein structure, interactions with binding partners, functions in mammalian cells, and the generation of various new model systems. Accordingly, this is now an opportune time to pause and review the function and mechanisms of action of EHD proteins, and to highlight some of the challenges and future directions for the field. PMID:21067929

  1. Reversible mode of binding of serum proteins to DOTAP/cholesterol Lipoplexes: a possible explanation for intravenous lipofection efficiency.

    Science.gov (United States)

    Simberg, Dmitri; Weiss, Aryeh; Barenholz, Yechezkel

    2005-09-01

    There are many indications that interaction of serum proteins with intravenously injected cationic lipoplexes disturbs lipofection in vitro and in vivo. However, transfection with certain lipid compositions such as N-[1- (2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP)/cholesterol appears to be more resistant to serum and more efficacious. We investigated the mechanism of interaction between fluorescently labeled lipoplexes of the above composition and fluorescently labeled serum proteins. Fluorescence resonance energy transfer measurements in vitro indicate that serum proteins interact instantly and closely with the DOTAP/cholesterol lipoplexes. In accord with this, preinjection of fluorescently labeled serum into mice before injection of lipoplexes showed an immediate association of proteins with lipoplexes. Serum proteins colocalized with the lipoplexes in the lung vasculature; however, they dissociated from the cationic lipid as soon as 1 hr postinjection, probably because of displacement of serum proteins from lipoplexes by extracellular proteoglycans. Indeed, this displacement was imitated by heparin, a typical glycosaminoglycan, and could be explained by the inability of weakly acidic serum proteins to neutralize the DOTAP/cholesterol electrical surface potential psi0. The stability of the cationic lipid psi0 in serum could be a key reason for the high lung association and transfection efficiency with this formulation.

  2. A compact, multifunctional fusion module directs cholesterol-dependent homomultimerization and syncytiogenic efficiency of reovirus p10 FAST proteins.

    Directory of Open Access Journals (Sweden)

    Tim Key

    2014-03-01

    Full Text Available The homologous p10 fusion-associated small transmembrane (FAST proteins of the avian (ARV and Nelson Bay (NBV reoviruses are the smallest known viral membrane fusion proteins, and are virulence determinants of the fusogenic reoviruses. The small size of FAST proteins is incompatible with the paradigmatic membrane fusion pathway proposed for enveloped viral fusion proteins. Understanding how these diminutive viral fusogens mediate the complex process of membrane fusion is therefore of considerable interest, from both the pathogenesis and mechanism-of-action perspectives. Using chimeric ARV/NBV p10 constructs, the 36-40-residue ectodomain was identified as the major determinant of the differing fusion efficiencies of these homologous p10 proteins. Extensive mutagenic analysis determined the ectodomain comprises two distinct, essential functional motifs. Syncytiogenesis assays, thiol-specific surface biotinylation, and liposome lipid mixing assays identified an ∼25-residue, N-terminal motif that dictates formation of a cystine loop fusion peptide in both ARV and NBV p10. Surface immunofluorescence staining, FRET analysis and cholesterol depletion/repletion studies determined the cystine loop motif is connected through a two-residue linker to a 13-residue membrane-proximal ectodomain region (MPER. The MPER constitutes a second, independent motif governing reversible, cholesterol-dependent assembly of p10 multimers in the plasma membrane. Results further indicate that: (1 ARV and NBV homomultimers segregate to distinct, cholesterol-dependent microdomains in the plasma membrane; (2 p10 homomultimerization and cholesterol-dependent microdomain localization are co-dependent; and (3 the four juxtamembrane MPER residues present in the multimerization motif dictate species-specific microdomain association and homomultimerization. The p10 ectodomain therefore constitutes a remarkably compact, multifunctional fusion module that directs syncytiogenic

  3. Effect of growth hormone replacement therapy on plasma lecithin:cholesterol acyltransferase and lipid transfer protein activities in growth hormone-deficient adults

    NARCIS (Netherlands)

    J.A. Beentjes; A. van Tol (Arie); W.J. Sluiter (Wim); R.P.F. Dullaart (Robin)

    2000-01-01

    textabstractThe effects of growth hormone (GH) replacement on plasma lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP), and phospholipid transfer protein (PLTP), factors involved in high density lipoprotein (HDL) metabolism, are

  4. The effect of simvastatin treatment on the amyloid precursor protein and brain cholesterol metabolism in patients with Alzheimer's disease

    DEFF Research Database (Denmark)

    Hoglund, K; Thelen, K M; Syversen, S

    2005-01-01

    During the last years, several clinical studies have been published trying to elucidate the effect of statin treatment on amyloid precursor protein (APP) processing and metabolism of brain cholesterol in Alzheimer's disease (AD) in humans. We present an open biochemical study where 19 patients...... with AD have been treated with simvastatin (20 mg/day) for 12 months. The aim was to further investigate the effect of simvastatin treatment on cerebrospinal fluid (CSF) biomarkers of APP processing, AD biomarkers as total tau and tau phosphorylated at threonine 181, brain cholesterol metabolism as well...... as on cognitive decline in patients with AD. Despite biochemical data suggesting that treatment with 20 mg/day of simvastatin for 12 months does affect the brain cholesterol metabolism, we did not find any change in CSF or plasma levels of beta-amyloid (Abeta)(1-42). However, by analysis of APP isoforms, we found...

  5. Cholesterol Promotes Protein Binding by Affecting Membrane Electrostatics and Solvation Properties.

    Science.gov (United States)

    Doktorova, Milka; Heberle, Frederick A; Kingston, Richard L; Khelashvili, George; Cuendet, Michel A; Wen, Yi; Katsaras, John; Feigenson, Gerald W; Vogt, Volker M; Dick, Robert A

    2017-11-07

    Binding of the retroviral structural protein Gag to the cellular plasma membrane is mediated by the protein's matrix (MA) domain. Prominent among MA-PM interactions is electrostatic attraction between the positively charged MA domain and the negatively charged plasma membrane inner leaflet. Previously, we reported that membrane association of HIV-1 Gag, as well as purified Rous sarcoma virus (RSV) MA and Gag, depends strongly on the presence of acidic lipids and is enhanced by cholesterol (Chol). The mechanism underlying this enhancement was unclear. Here, using a broad set of in vitro and in silico techniques we addressed molecular mechanisms of association between RSV MA and model membranes, and investigated how Chol enhances this association. In neutron scattering experiments with liposomes in the presence or absence of Chol, MA preferentially interacted with preexisting POPS-rich clusters formed by nonideal lipid mixing, binding peripherally to the lipid headgroups with minimal perturbation to the bilayer structure. Molecular dynamics simulations showed a stronger MA-bilayer interaction in the presence of Chol, and a large Chol-driven increase in lipid packing and membrane surface charge density. Although in vitro MA-liposome association is influenced by disparate variables, including ionic strength and concentrations of Chol and charged lipids, continuum electrostatic theory revealed an underlying dependence on membrane surface potential. Together, these results conclusively show that Chol affects RSV MA-membrane association by making the electrostatic potential at the membrane surface more negative, while decreasing the penalty for lipid headgroup desolvation. The presented approach can be applied to other viral and nonviral proteins. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Cholesterol-dependent energy transfer between fluorescent proteins-insights into protein proximity of APP and BACE1 in different membranes in Niemann-Pick type C disease cells.

    Science.gov (United States)

    von Einem, Bjoern; Weber, Petra; Wagner, Michael; Malnar, Martina; Kosicek, Marko; Hecimovic, Silva; Arnim, Christine A F von; Schneckenburger, Herbert

    2012-11-26

    Förster resonance energy transfer (FRET) -based techniques have recently been applied to study the interactions between β-site APP-cleaving enzyme-GFP (BACE1-GFP) and amyloid precursor protein-mRFP (APP-mRFP) in U373 glioblastoma cells. In this context, the role of APP-BACE1 proximity in Alzheimer's disease (AD) pathogenesis has been discussed. FRET was found to depend on intracellular cholesterol levels and associated alterations in membrane stiffness. Here, NPC1 null cells (CHO-NPC1-/-), exhibiting increased cholesterol levels and disturbed cholesterol transport similar to that observed in Niemann-Pick type C disease (NPC), were used to analyze the influence of altered cholesterol levels on APP-BACE1 proximity. Fluorescence lifetime measurements of whole CHO-wild type (WT) and CHO-NPC1-/- cells (EPI-illumination microscopy), as well as their plasma membranes (total internal reflection fluorescence microscopy, TIRFM), were performed. Additionally, generalized polarization (GP) measurements of CHO-WT and CHO-NPC1-/- cells incubated with the fluorescence marker laurdan were performed to determine membrane stiffness of plasma- and intracellular-membranes. CHO-NPC1-/- cells showed higher membrane stiffness at intracellular- but not plasma-membranes, equivalent to cholesterol accumulation in late endosomes/lysosomes. Along with higher membrane stiffness, the FRET efficiency between BACE1-GFP and APP-mRFP was reduced at intracellular membranes, but not within the plasma membrane of CHO-NPC1-/-. Our data show that FRET combined with TIRF is a powerful technique to determine protein proximity and membrane fluidity in cellular models of neurodegenerative diseases.

  7. Transport proteins promoting Escherichia coli pathogenesis

    Science.gov (United States)

    Tang, Fengyi; Saier, Milton H.

    2014-01-01

    Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies. PMID:24747185

  8. Transport proteins promoting Escherichia coli pathogenesis.

    Science.gov (United States)

    Tang, Fengyi; Saier, Milton H

    2014-01-01

    Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Semantic role labeling for protein transport predicates

    Directory of Open Access Journals (Sweden)

    Martin James H

    2008-06-01

    Full Text Available Abstract Background Automatic semantic role labeling (SRL is a natural language processing (NLP technique that maps sentences to semantic representations. This technique has been widely studied in the recent years, but mostly with data in newswire domains. Here, we report on a SRL model for identifying the semantic roles of biomedical predicates describing protein transport in GeneRIFs – manually curated sentences focusing on gene functions. To avoid the computational cost of syntactic parsing, and because the boundaries of our protein transport roles often did not match up with syntactic phrase boundaries, we approached this problem with a word-chunking paradigm and trained support vector machine classifiers to classify words as being at the beginning, inside or outside of a protein transport role. Results We collected a set of 837 GeneRIFs describing movements of proteins between cellular components, whose predicates were annotated for the semantic roles AGENT, PATIENT, ORIGIN and DESTINATION. We trained these models with the features of previous word-chunking models, features adapted from phrase-chunking models, and features derived from an analysis of our data. Our models were able to label protein transport semantic roles with 87.6% precision and 79.0% recall when using manually annotated protein boundaries, and 87.0% precision and 74.5% recall when using automatically identified ones. Conclusion We successfully adapted the word-chunking classification paradigm to semantic role labeling, applying it to a new domain with predicates completely absent from any previous studies. By combining the traditional word and phrasal role labeling features with biomedical features like protein boundaries and MEDPOST part of speech tags, we were able to address the challenges posed by the new domain data and subsequently build robust models that achieved F-measures as high as 83.1. This system for extracting protein transport information from Gene

  10. Genetic variation in the cholesterol transporter NPC1L1, ischaemic vascular disease, and gallstone disease

    DEFF Research Database (Denmark)

    Lauridsen, Bo Kobberø; Stender, Stefan; Frikke-Schmidt, Ruth

    2015-01-01

    developed IVD or symptomatic gallstone disease, respectively, during follow-up from 1977 to 2013. We genotyped four common NPC1L1 variants, previously associated with reduced LDL cholesterol levels, thus mimicking the effect of ezetimibe, and calculated a weighted genotype score. With increasing genotype...

  11. Cognition, learning behaviour and hippocampal synaptic plasticity are not disrupted in mice over-expressing the cholesterol transporter ABCG1

    Directory of Open Access Journals (Sweden)

    Eadie Brennan D

    2009-02-01

    Full Text Available Abstract Background Cognitive deficits are a hallmark feature of both Down Syndrome (DS and Alzheimer's Disease (AD. Extra copies of the genes on chromosome 21 may also play an important role in the accelerated onset of AD in DS individuals. Growing evidence suggests an important function for cholesterol in the pathogenesis of AD, particularly in APP metabolism and production of Aβ peptides. The ATP-Binding Cassette-G1 (ABCG1 transporter is located on chromosome 21, and participates in the maintenance of tissue cholesterol homeostasis. Results To assess the role of ABCG1 in DS-related cognition, we evaluated the cognitive performance of mice selectively over-expressing the ABCG1 gene from its endogenous regulatory signals. Both wild-type and ABCG1 transgenic mice performed equivalently on several behavioral tests, including measures of anxiety, as well as on reference and working memory tasks. No deficits in hippocampal CA1 synaptic plasticity as determined with electrophysiological studies were apparent in mice over-expressing ABCG1. Conclusion These findings indicate that although ABCG1 may play a role in maintaining cellular or tissue cholesterol homeostasis, it is unlikely that excess ABCG1 expression contributes to the cognitive deficits in DS individuals.

  12. What's Cholesterol?

    Science.gov (United States)

    ... LDL. Most cholesterol is LDL (low-density lipoprotein) cholesterol. LDL cholesterol is more likely to clog blood vessels because ... Here's a way to remember the difference: the LDL cholesterol is the bad kind, so call it "lousy" ...

  13. Complement Activation by Ceramide Transporter Proteins

    NARCIS (Netherlands)

    Bode, G.H.; Losen, M.; Buurman, W.A.; Veerhuis, R.; Molenaar, P.C.; Steinbusch, H.W.M.; De Baets, M.H.; Daha, MR; Martinez-Martinez, P.

    2014-01-01

    C1q is the initiator of the classical complement pathway and, as such, is essential for efficient opsonization and clearance of pathogens, altered self-structures, and apoptotic cells. The ceramide transporter protein (CERT) and its longer splicing isoform CERTL are known to interact with

  14. Cholesterol and polyunsaturated lipids working in concert to modulate G protein-coupled receptors

    Czech Academy of Sciences Publication Activity Database

    Javanainen, M.; Manna, M.; Vähäheikkilä, M.; Niemelä, M.; Tynkkynen, J.; Guixa-Gonzaléz, R.; Martinez-Seara, Hector; Enkavi, G.; Kulig, W.; Müller, D. J.; Rog, T.; Vattulainen, I.

    2017-01-01

    Roč. 46, Suppl 1 (2017), S47 ISSN 0175-7571. [IUPAB congress /19./ and EBSA congress /11./. 16.07.2017-20.07.2017, Edinburgh] Institutional support: RVO:61388963 Keywords : GPCR * cholesterol * lipids Subject RIV: BO - Biophysics

  15. Decreased Retinol Binding Protein 4 Concentrations are Associated With Cholesterol Gallstone Disease

    Directory of Open Access Journals (Sweden)

    Shen-Nien Wang

    2010-06-01

    Conclusion: Circulating RBP4 decreases in cholesterol gallstone disease independent of renal function. Further studies are needed to investigate the relationship between liver function and RBP4 levels in these patients.

  16. Transporters for the Intestinal Absorption of Cholesterol, Vitamin E, and Vitamin K

    OpenAIRE

    Yamanashi, Yoshihide; Takada, Tappei; Kurauchi, Ryoya; Tanaka, Yusuke; Komine, Toko; Suzuki, Hiroshi

    2017-01-01

    Humans cannot synthesize fat-soluble vitamins such as vitamin E and vitamin K. For this reason, they must be obtained from the diet via intestinal absorption. As the deficiency or excess of these vitamins has been reported to cause several types of diseases and disorders in humans, the intestinal absorption of these nutrients must be properly regulated to ensure good health. However, the mechanism of their intestinal absorption remains poorly understood. Recent studies on cholesterol using ge...

  17. Distribution and Spectroscopy of Green Fluorescent Protein and Acyl-CoA: Cholesterol Acytransferase in Sf21 Insect Cells

    Science.gov (United States)

    Richmond, R. C.; Mahtani, H.; Lu, X.; Chang, T. Y.; Malak, H.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Acyl-CoA: cholesterol acyltransferase (ACAT) is thought to significantly participate in the pathway of cholesterol esterification that underlies the pathology of artherosclerosis. This enzyme is a membrane protein known to be preferentially bound within the endoplasmic reticulum of mammalian cells, from which location it esterifies cholesterol derived from low density lipoprotein. Cultures of insect cells were separately infected with baculovirus containing the gene for green fluroescent protein (GFP) and with baculovirus containing tandem genes for GFP and ACAT. These infected cultures expressed GFP and the fusion protein GCAT, respectively, with maximum expression occurring on the fourth day after infection. Extraction of GFP- and of GCAT-expressing cells with urea and detergent resulted in recovery of fluorescent protein in aqueous solution. Fluorescence spectra at neutral pH were identical for both GFP and GCAT extracts in aqueous solution, indicating unperturbed tertiary structure for the GFP moiety within GCAT. In a cholesterol esterification assay, GCAT demonstrated ACAT activity, but with less efficiency compared to native ACAT. It was hypothesized that the membrane protein ACAT would lead to differences in localization of GCAT compared to GFP within the respective expressing insect cells. The GFP marker directly and also within the fusion protein GCAT was accordingly used as the intracellular probe that was fluorescently analyzed by the new biophotonics technique of hyperspectral imaging. In that technique, fluorescence imaging was obtained from two dimensional arrays of cells, and regions of interest from within those images were then retrospectively analyzed for the emission spectra that comprises the image. Results of hyperspectral imaging of insect cells on day 4 postinfection showed that GCAT was preferentially localized to the cytoplasm of these cells compared to GFP. Furthermore, the emission spectra obtained for the localized GCAT displayed a peak

  18. Differential mRNA expression of seven genes involved in cholesterol metabolism and transport in the liver of atherosclerosis-susceptible and -resistant Japanese quail strains

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    Li Xinrui

    2012-06-01

    Full Text Available Abstract Background Two atherosclerosis-susceptible and -resistant Japanese quail (Coturnix japonica strains obtained by divergent selection are commonly used as models to study atherosclerosis, but no genetic characterization of their phenotypic differences has been reported so far. Our objective was to examine possible differences in the expression of genes involved in cholesterol metabolism and transport in the liver between these two strains and to evaluate the value of this model to analyze the gene system affecting cholesterol metabolism and transport. Methods A factorial study with both strains (atherosclerosis-susceptible versus atherosclerosis-resistant and two diets (control versus cholesterol was carried out. The mRNA concentrations of four genes involved in cholesterol biosynthesis (HMGCR, FDFT1, SQLE and DHCR7 and three genes in cholesterol transport (ABCG5, ABCG8 and APOA1 were assayed using real-time quantitative PCR. Plasma lipids were also assayed. Results Expression of ABCG5 (control diet and ABCG8 (regardless of dietary treatment and expression of HMGCR, FDFT1 and SQLE (regardless of dietary treatment were significantly higher in the atherosclerosis-resistant than in the atherosclerosis-susceptible strain. Plasma triglyceride and LDL levels, and LDL/HDL ratio were significantly higher in the atherosclerosis-susceptible than in the atherosclerosis-resistant strain fed the cholesterol diet. In the atherosclerosis-susceptible strain, ABCG5 expression regressed significantly and positively on plasma LDL level, whereas DHCR7 and SQLE expression regressed significantly and negatively on plasma triglyceride level. Conclusions Our results provide support for the hypothesis that the atherosclerosis-resistant strain metabolizes and excretes cholesterol faster than the atherosclerosis-susceptible strain. We have also demonstrated that these quail strains are a useful model to study cholesterol metabolism and transport in relation with

  19. Isoflavone and Protein Constituents of Lactic Acid-Fermented Soy Milk Combine to Prevent Dyslipidemia in Rats Fed a High Cholesterol Diet

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    Maki Kobayashi

    2014-12-01

    Full Text Available A high cholesterol diet induces dyslipidemia. This study investigated whether isoflavone aglycones in lactic acid-fermented soy milk (LFS improve lipid metabolism in rats fed a high cholesterol diet. Male Sprague-Dawley rats aged seven weeks were fed an AIN-93G diet, a 1% cholesterol diet (a high cholesterol diet, a high-cholesterol diet containing 4% isoflavone extract of LFS (LFS extract diet, a high-cholesterol diet containing 19.4% ethanol-washed LFS (ethanol-washed LFS diet, isoflavone-poor diet, or a high cholesterol diet containing 23.2% intact LFS (intact LFS diet for five weeks. The plasma total cholesterol (TC level was increased in the rats fed the LFS extract diet compared with those fed the high cholesterol diet. The TC level was decreased by the intact LFS and ethanol-washed LFS diets. The cholesterol-lowering effect was stronger in the rats fed the intact LFS diet than those fed the ethanol-washed LFS diet. The plasma triglyceride (TG level was unchanged in the rats fed the LFS extract diet, but it decreased in rats fed the intact LFS and ethanol-washed LFS diets. Although, compared with the high cholesterol diet, the LFS extract and ethanol-washed LFS diets did not reduce hepatic cholesterol and TG, both levels were remarkably lowered by the intact LFS diet. These results suggest that the improvement in lipid metabolism of rats fed a high-cholesterol diet containing LFS isoflavone aglycones is not due to an independent effect but due to a cooperative effect with soy protein.

  20. Isoflavone and Protein Constituents of Lactic Acid-Fermented Soy Milk Combine to Prevent Dyslipidemia in Rats Fed a High Cholesterol Diet

    Science.gov (United States)

    Kobayashi, Maki; Egusa, Shintaro; Fukuda, Mitsuru

    2014-01-01

    A high cholesterol diet induces dyslipidemia. This study investigated whether isoflavone aglycones in lactic acid-fermented soy milk (LFS) improve lipid metabolism in rats fed a high cholesterol diet. Male Sprague-Dawley rats aged seven weeks were fed an AIN-93G diet, a 1% cholesterol diet (a high cholesterol diet), a high-cholesterol diet containing 4% isoflavone extract of LFS (LFS extract diet), a high-cholesterol diet containing 19.4% ethanol-washed LFS (ethanol-washed LFS diet, isoflavone-poor diet), or a high cholesterol diet containing 23.2% intact LFS (intact LFS diet) for five weeks. The plasma total cholesterol (TC) level was increased in the rats fed the LFS extract diet compared with those fed the high cholesterol diet. The TC level was decreased by the intact LFS and ethanol-washed LFS diets. The cholesterol-lowering effect was stronger in the rats fed the intact LFS diet than those fed the ethanol-washed LFS diet. The plasma triglyceride (TG) level was unchanged in the rats fed the LFS extract diet, but it decreased in rats fed the intact LFS and ethanol-washed LFS diets. Although, compared with the high cholesterol diet, the LFS extract and ethanol-washed LFS diets did not reduce hepatic cholesterol and TG, both levels were remarkably lowered by the intact LFS diet. These results suggest that the improvement in lipid metabolism of rats fed a high-cholesterol diet containing LFS isoflavone aglycones is not due to an independent effect but due to a cooperative effect with soy protein. PMID:25514389

  1. Cholesterol Removal from Adult Skeletal Muscle impairs Excitation-Contraction Coupling and Aging reduces Caveolin-3 and alters the Expression of other Triadic Proteins

    Directory of Open Access Journals (Sweden)

    Genaro eBarrientos

    2015-04-01

    Full Text Available Cholesterol and caveolin are integral membrane components that modulate the function/location of many cellular proteins. Skeletal muscle fibers, which have unusually high cholesterol levels in transverse tubules, express the caveolin-3 isoform but its association with transverse tubules remains contentious. Cholesterol removal impairs excitation-contraction coupling in amphibian and mammalian fetal skeletal muscle fibers. Here, we show that treating single muscle fibers from adult mice with the cholesterol removing agent methyl-β-cyclodextrin decreased fiber cholesterol by 26%, altered the location pattern of caveolin-3 and of the voltage dependent calcium channel Cav1.1, and suppressed or reduced electrically evoked Ca2+ transients without affecting membrane integrity or causing sarcoplasmic reticulum calcium depletion. We found that transverse tubules from adult muscle and triad fractions that contain ~10% attached transverse tubules, but not sarcoplasmic reticulum membranes, contained caveolin-3 and Cav1.1; both proteins partitioned into detergent-resistant membrane fractions highly enriched in cholesterol. Aging entails significant deterioration of skeletal muscle function. We found that triad fractions from aged rats had similar cholesterol and RyR1 protein levels compared to triads from young rats, but had lower caveolin-3 and glyceraldehyde 3-phosphate dehydrogenase and increased Na+/K+-ATPase protein levels. Both triad fractions had comparable NADPH oxidase (NOX activity and protein content of NOX2 subunits (p47phox and gp91phox, implying that NOX activity does not increase during aging. These findings show that partial cholesterol removal impairs excitation-contraction coupling and alters caveolin-3 and Cav1.1 location pattern, and that aging reduces caveolin-3 protein content and modifies the expression of other triadic proteins. We discuss the possible implications of these findings for skeletal muscle function in young and aged

  2. Examination of the relation between periodontal health status and cardiovascular risk factors: serum total and high density lipoprotein cholesterol, C-reactive protein, and plasma fibrinogen.

    Science.gov (United States)

    Wu, T; Trevisan, M; Genco, R J; Falkner, K L; Dorn, J P; Sempos, C T

    2000-02-01

    Using data from the Third National Health and Nutrition Examination Survey (1988-1994), the authors examined the relation between periodontal health and cardiovascular risk factors: serum total and high density lipoprotein cholesterol, C-reactive protein, and plasma fibrinogen. A total of 10,146 participants were included in the analyses of cholesterol and C-reactive protein and 4,461 in the analyses of fibrinogen. Periodontal health indicators included the gingival bleeding index, calculus index, and periodontal disease status (defined by pocket depth and attachment loss). While cholesterol and fibrinogen were analyzed as continuous variables, C-reactive protein was dichotomized into two levels. The results show a significant relation between indicators of poor periodontal status and increased C-reactive protein and fibrinogen. The association between periodontal status and total cholesterol level is much weaker. No consistent association between periodontal status and high density lipoprotein cholesterol was detectable. Similar patterns of association were observed for participants aged 17-54 years and those 55 years and older. In conclusion, this study suggests that total cholesterol, C-reactive protein, and fibrinogen are possible intermediate factors that may link periodontal disease to elevated cardiovascular risk.

  3. Inhibitory effect of Piper betel leaf extracts on copper-mediated LDL oxidation and oxLDL-induced lipid accumulation via inducing reverse cholesterol transport in macrophages.

    Science.gov (United States)

    Ma, Gwo-Chin; Wu, Pei-Fang; Tseng, Hsien-Chun; Chyau, Charng-Cherng; Lu, Hsiu-Chin; Chou, Fen-Pi

    2013-12-15

    Piper betel leaf (PBL) has the biological capabilities of detoxification and can work as an anti-inflammatory agent and an anti-oxidant. In this study, we evaluated the anti-oxidative activity of the extract of Piper betel leaves (PBLs) on the basis of Cu(2+)-mediated oxidation, and its ability to prevent foam cell formation in a model for oxidised low density lipoprotein (oxLDL)-induced lipid accumulation in macrophages. Our data demonstrated that PBLs were able to inhibit LDL oxidation in vitro and are able to reduce the lipid accumulation in macrophages. We showed the underlying mechanisms to be the following: PBLs up-regulated the protein levels of the class A and class B scavenger receptors, the membrane lipid transporter ABCA1, and its upstream regulator Liver X receptor (LXR) in the macrophages exposed to oxLDL. The results suggested that PBLs activated the reverse cholesterol transport mechanism to enhance the metabolism of the oxLDL that could prevent both lipid accumulation and foam cell formation and further minimise the possible damage of vessels caused by the oxLDL. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Rapid Diagnosis of 83 Patients with Niemann Pick Type C Disease and Related Cholesterol Transport Disorders by Cholestantriol Screening

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    Janine Reunert

    2016-02-01

    Full Text Available Niemann Pick type C (NP-C is a rare neurodegenerative disorder caused by an impairment of intracellular lipid transport. Due to the heterogeneous clinical phenotype and the lack of a reliable blood test, diagnosis and therapy are often delayed for years. In the cell, accumulating cholesterol leads to increased formation of oxysterols that can be used as a powerful screening parameter for NP-C. In a large scale study, we evaluated the oxysterol cholestane-3β,5α,6β-triol (c-triol as potential biomarker for a rapid diagnosis of NP-C. Using GC/MS, c-triol has been analyzed in 1902 plasma samples of patients with the suspicion for NP-C. Diagnosis in patients with elevated oxysterols was confirmed by genetic analysis. 71 new NP-C patients (69 NP-C1 and two NP-C2 and 12 Niemann Pick type A/B patients were identified. 24 new mutations in NPC1, one new mutation in NPC2 and three new mutations in the SMPD1 gene were found. Cholestane-3β,5α,6β-triol was elevated in Niemann Pick type C1, type C2, type A/B and in CESD disease. No other study has ever identified so many NP-C patients, proving that c-triol is a rapid and reliable biomarker to detect patients with NP-C disease and related cholesterol transport disorders. It should replace the filipin test as the first-line diagnostic assay.

  5. An Essential Role of Hrs/Vps27 in Endosomal Cholesterol Trafficking

    Directory of Open Access Journals (Sweden)

    Ximing Du

    2012-01-01

    Full Text Available The endosomal sorting complex required for transport (ESCRT plays a crucial role in the degradation of ubiquitinated endosomal membrane proteins. Here, we report that Hrs, a key protein of the ESCRT-0 complex, is required for the transport of low-density lipoprotein-derived cholesterol from endosomes to the endoplasmic reticulum. This function of Hrs in cholesterol transport is distinct from its previously defined role in lysosomal sorting and downregulation of membrane receptors via the ESCRT pathway. In line with this, knocking down other ESCRT proteins does not cause prominent endosomal cholesterol accumulation. Importantly, the localization and biochemical properties of key cholesterol-sorting proteins, NPC1 and NPC2, appear to be unchanged upon Hrs knockdown. Our data identify Hrs as a regulator of endosomal cholesterol trafficking and provide additional insights into the budding of intralumenal vesicles.

  6. Fluorescence spectroscopy studies of HEK293 cells expressing DOR-Gi1alfa fusion protein; the effect of cholesterol depletion

    Czech Academy of Sciences Publication Activity Database

    Brejchová, Jana; Sýkora, Jan; Dlouhá, Kateřina; Roubalová, Lenka; Ostašov, Pavel; Vošahlíková, Miroslava; Hof, Martin; Svoboda, Petr

    2011-01-01

    Roč. 1808, č. 12 (2011), s. 2819-2829 ISSN 0005-2736 R&D Projects: GA MŠk(CZ) LC06063; GA MŠk(CZ) LC554; GA ČR(CZ) GD305/08/H037 Grant - others:GA ČR(CZ) GAP208/10/1090 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z40400503 Keywords : plasma membrane * cholesterol depletion * fluorescence spectroscopy * hydrophobic membrane interior * delta-opioid receptor ( DOR ), * G protein Subject RIV: BO - Biophysics Impact factor: 3.990, year: 2011

  7. MicroRNA-20a/b regulates cholesterol efflux through post-transcriptional repression of ATP-binding cassette transporter A1.

    Science.gov (United States)

    Liang, Bin; Wang, Xin; Song, Xiaosu; Bai, Rui; Yang, Huiyu; Yang, Zhiming; Xiao, Chuanshi; Bian, Yunfei

    2017-09-01

    ATP-binding cassette transporter A1 (ABCA1) plays a crucial role in reverse cholesterol transport and exhibits anti-atherosclerosis effects. Some microRNAs (miRs) regulate ABCA1 expression, and recent studies have shown that miR-20a/b might play a critical role in atherosclerotic diseases. Here, we attempted to clarify the potential contribution of miR-20a/b in post-transcriptional regulation of ABCA1, cholesterol efflux, and atherosclerosis. We performed bioinformatics analysis and found that miR-20a/b was highly conserved and directly bound to ABCA1 mRNA with low binding free energy. Luciferase-reporter assay also confirmed that miR-20a/b significantly reduced luciferase activity associated with the ABCA1 3' untranslated region reporter construct. Additionally, miR-20a/b decreased ABCA1 expression, which, in turn, decreased cholesterol efflux and increased cholesterol content in THP-1 and RAW 264.7 macrophage-derived foam cells. In contrast, miR-20a/b inhibitors increased ABCA1 expression and cholesterol efflux, decreased cholesterol content, and inhibited foam-cell formation. Consistent with our in vitro results, miR-20a/b-treated ApoE -/- mice showed decreased ABCA1expression in the liver and reductions of reverse cholesterol transport in vivo. Furthermore, miR-20a/b regulated the formation of nascent high-density lipoprotein and promoted atherosclerotic development, whereas miR-20a/b knockdown attenuated atherosclerotic formation. miR-20 is a new miRNA capable of targeting ABCA1 and regulating ABCA1 expression. Therefore, miR-20 inhibition constitutes a new strategy for ABCA1-based treatment of atherosclerosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Complement activation by ceramide transporter proteins.

    Science.gov (United States)

    Bode, Gerard H; Losen, Mario; Buurman, Wim A; Veerhuis, Robert; Molenaar, Peter C; Steinbusch, Harry W M; De Baets, Marc H; Daha, Mohamed R; Martinez-Martinez, Pilar

    2014-02-01

    C1q is the initiator of the classical complement pathway and, as such, is essential for efficient opsonization and clearance of pathogens, altered self-structures, and apoptotic cells. The ceramide transporter protein (CERT) and its longer splicing isoform CERTL are known to interact with extracellular matrix components, such as type IV collagen, and with the innate immune protein serum amyloid P. In this article, we report a novel function of CERT in the innate immune response. Both CERT isoforms, when immobilized, were found to bind the globular head region of C1q and to initiate the classical complement pathway, leading to activation of C4 and C3, as well as generation of the membrane attack complex C5b-9. In addition, C1q was shown to bind to endogenous CERTL on the surface of apoptotic cells. These results demonstrate the role of CERTs in innate immunity, especially in the clearance of apoptotic cells.

  9. The Human ABCG1 Transporter Mobilizes Plasma Membrane and Late Endosomal Non-Sphingomyelin-Associated-Cholesterol for Efflux and Esterification

    Directory of Open Access Journals (Sweden)

    Edward B. Neufeld

    2014-12-01

    Full Text Available We have previously shown that GFP-tagged human ABCG1 on the plasma membrane (PM and in late endosomes (LE mobilizes sterol on both sides of the membrane lipid bilayer, thereby increasing cellular cholesterol efflux to lipid surfaces. In the present study, we examined ABCG1-induced changes in membrane cholesterol distribution, organization, and mobility. ABCG1-GFP expression increased the amount of mobile, non-sphingomyelin(SM-associated cholesterol at the PM and LE, but not the amount of SM-associated-cholesterol or SM. ABCG1-mobilized non-SM-associated-cholesterol rapidly cycled between the PM and LE and effluxed from the PM to extracellular acceptors, or, relocated to intracellular sites of esterification. ABCG1 increased detergent-soluble pools of PM and LE cholesterol, generated detergent-resistant, non-SM-associated PM cholesterol, and increased resistance to both amphotericin B-induced (cholesterol-mediated and lysenin-induced (SM-mediated cytolysis, consistent with altered organization of both PM cholesterol and SM. ABCG1 itself resided in detergent-soluble membrane domains. We propose that PM and LE ABCG1 residing at the phase boundary between ordered (Lo and disordered (Ld membrane lipid domains alters SM and cholesterol organization thereby increasing cholesterol flux between Lo and Ld, and hence, the amount of cholesterol available for removal by acceptors on either side of the membrane bilayer for either efflux or esterification.

  10. Phytosterol and cholesterol precursor levels indicate increased cholesterol excretion and biosynthesis in gallstone disease.

    Science.gov (United States)

    Krawczyk, Marcin; Lütjohann, Dieter; Schirin-Sokhan, Ramin; Villarroel, Luis; Nervi, Flavio; Pimentel, Fernando; Lammert, Frank; Miquel, Juan Francisco

    2012-05-01

    In hepatocytes and enterocytes sterol uptake and secretion is mediated by Niemann-Pick C1-like 1 (NPC1L1) and ATP-binding cassette (ABC)G5/8 proteins, respectively. Whereas serum levels of phytosterols represent surrogate markers for intestinal cholesterol absorption, cholesterol precursors reflect cholesterol biosynthesis. Here we compare serum and biliary sterol levels in ethnically different populations of patients with gallstone disease (GSD) and stone-free controls to identify differences in cholesterol transport and synthesis between these groups. In this case-control study four cohorts were analyzed: 112 German patients with GSD and 152 controls; two distinct Chilean ethnic groups: Hispanics (100 GSD, 100 controls), and Amerindians (20 GSD, 20 controls); additionally an 8-year follow-up of 70 Hispanics was performed. Serum sterols were measured by gas chromatography / mass spectrometry. Gallbladder bile sterol levels were analyzed in cholesterol GSD and controls. Common ABCG5/8 variants were genotyped. Comparison of serum sterols showed lower levels of phytosterols and higher levels of cholesterol precursors in GSD patients than in controls. The ratios of phytosterols to cholesterol precursors were lower in GSD patients, whereas biliary phytosterol and cholesterol concentrations were elevated as compared with controls. In the follow-up study, serum phytosterol levels were significantly lower even before GSD was detectable by ultrasound. An ethnic gradient in the ratios of phytosterols to cholesterol precursors was apparent (Germans > Hispanics > Amerindians). ABCG5/8 variants did not fully explain the sterol metabolic trait of GSD in any of the cohorts. Individuals predisposed to GSD display increased biliary output of cholesterol in the setting of relatively low intestinal cholesterol absorption, indicating enhanced whole-body sterol clearance. This metabolic trait precedes gallstone formation and is a feature of ethnic groups at higher risk of cholesterol

  11. Expression of the Acyl-Coenzyme A: Cholesterol Acyltransferase GFP Fusion Protein in Sf21 Insect Cells

    Science.gov (United States)

    Mahtani, H. K.; Richmond, R. C.; Chang, T. Y.; Chang, C. C. Y.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    The enzyme acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an important contributor to the pathological expression of plaque leading to artherosclerosis n a major health problem. Adequate knowledge of the structure of this protein will enable pharmaceutical companies to design drugs specific to the enzyme. ACAT is a membrane protein located in the endoplasmic reticulum.t The protein has never been purified to homogeneity.T.Y. Chang's laboratory at Dartmouth College provided a 4-kb cDNA clone (K1) coding for a structural gene of the protein. We have modified the gene sequence and inserted the cDNA into the BioGreen His Baculovirus transfer vector. This was successfully expressed in Sf2l insect cells as a GFP-labeled ACAT protein. The advantage to this ACAT-GFP fusion protein (abbreviated GCAT) is that one can easily monitor its expression as a function of GFP excitation at 395 nm and emission at 509 nm. Moreover, the fusion protein GCAT can be detected on Western blots with the use of commercially available GFP antibodies. Antibodies against ACAT are not readily available. The presence of the 6xHis tag in the transfer vector facilitates purification of the recombinant protein since 6xHis fusion proteins bind with high affinity to Ni-NTA agarose. Obtaining highly pure protein in large quantities is essential for subsequent crystallization. The purified GCAT fusion protein can readily be cleaved into distinct GFP and ACAT proteins in the presence of thrombin. Thrombin digests the 6xHis tag linking the two protein sequences. Preliminary experiments have indicated that both GCAT and ACAT are expressed as functional proteins. The ultimate aim is to obtain large quantities of the ACAT protein in pure and functional form appropriate for protein crystal growth. Determining protein structure is the key to the design and development of effective drugs. X-ray analysis requires large homogeneous crystals that are difficult to obtain in the gravity environment of earth

  12. Detergent insolubility of alkaline phosphatase during biosynthetic transport and endocytosis. Role of cholesterol

    NARCIS (Netherlands)

    Cerneus, D. P.; Ueffing, E.; Posthuma, G.; Strous, G. J.; van der Ende, A.

    1993-01-01

    Alkaline phosphatase is anchored to the outer leaflet of the plasma membrane by a covalently attached glycosyl-phosphatidylinositol anchor. We have studied the biosynthetic transport and endocytosis of alkaline phosphatase in the choriocarcinoma cell line BeWo, which endogenously expresses this

  13. The association of 83 plasma proteins with CHD mortality, BMI, HDL-, and total-cholesterol in men: Applying multivariate statistics to identify proteins with prognostic value and biological relevance

    NARCIS (Netherlands)

    Geert Heidema, A.; Thissen, U.; Boer, J.M.A.; Bouwman, F.G.; Feskens, E.J.M.; Mariman, E.C.M.

    2009-01-01

    In this study, we applied the multivariate statistical tool Partial Least Squares (PLS) to analyze the relative importance of 83 plasma proteins in relation to coronary heart disease (CHD) mortality and the intermediate end points body mass index, HDL-cholesterol and total cholesterol. From a Dutch

  14. Type I diabetes mellitus decreases in vivo macrophage-to-feces reverse cholesterol transport despite increased biliary sterol secretion in mice

    NARCIS (Netherlands)

    de Boer, Jan Freark; Annema, Wijtske; Schreurs, Marijke; van der Veen, Jelske N; van der Giet, Markus; Nijstad, Niels; Kuipers, Folkert; Tietge, Uwe J F

    Type I diabetes mellitus (T1DM) increases atherosclerotic cardiovascular disease; however, the underlying pathophysiology is still incompletely understood. We investigated whether experimental T1DM impacts HDL-mediated reverse cholesterol transport (RCT). C57BL/6J mice with alloxan-induced T1DM had

  15. Chlordecone altered hepatic disposition of [14C]cholesterol and plasma cholesterol distribution but not SR-BI or ABCG8 proteins in livers of C57BL/6 mice

    International Nuclear Information System (INIS)

    Lee, Junga; Scheri, Richard C.; Curtis, Lawrence R.

    2008-01-01

    Organochlorine (OC) insecticides continue to occur in tissues of humans and wildlife throughout the world although they were banned in the United States a few decades ago. Low doses of the OC insecticide chlordecone (CD) alter hepatic disposition of lipophilic xenobiotics and perturb lipid homeostasis in rainbow trout, mice and rats. CD pretreatment altered tissue and hepatic subcellular distribution of exogenous [ 14 C]cholesterol (CH) equivalents 4 and 16 h after a bolus intraperitoneal (ip) injection of 5 ml corn oil/kg that contained 10 mg CH/kg. CD pretreatment altered tissue distribution of exogenously administered [ 14 C]CH by decreased hepatic and renal accumulation, and increased biliary excretion up to 300%. Biliary excretion of polar [ 14 C]CH metabolites was not altered by CD. CD pretreatment decreased subcellular distribution of [ 14 C]CH equivalents in hepatic cytosol and microsomes and lipoprotein-rich fraction-to-homogenate ratio. CD pretreatment increased the ratio of [ 14 C]CH equivalents in high density lipoprotein (HDL) to that in plasma and reduced [ 14 C]CH equivalents in the non-HDL fraction 4 h after a bolus lipid dose. CD pretreatment increased plasma non-HDL total CH by 80% 4 h after a bolus lipid dose. Scavenger receptor class B type I (SR-BI) and ATP-binding cassette transporter G8 (ABCG8) proteins were quantified by western blotting in hepatic membranes from control and CD treated mice. Liver membrane contents of SR-BI and ABCG8 proteins were unchanged by CD pretreatment. The data demonstrated that a single dose of CD altered CH homeostasis and lipoprotein metabolism

  16. Chlordecone altered hepatic disposition of [14C]cholesterol and plasma cholesterol distribution but not SR-BI or ABCG8 proteins in livers of C57BL/6 mice.

    Science.gov (United States)

    Lee, Junga; Scheri, Richard C; Curtis, Lawrence R

    2008-06-15

    Organochlorine (OC) insecticides continue to occur in tissues of humans and wildlife throughout the world although they were banned in the United States a few decades ago. Low doses of the OC insecticide chlordecone (CD) alter hepatic disposition of lipophilic xenobiotics and perturb lipid homeostasis in rainbow trout, mice and rats. CD pretreatment altered tissue and hepatic subcellular distribution of exogenous [(14)C]cholesterol (CH) equivalents 4 and 16 h after a bolus intraperitoneal (ip) injection of 5 ml corn oil/kg that contained 10 mg CH/kg. CD pretreatment altered tissue distribution of exogenously administered [(14)C]CH by decreased hepatic and renal accumulation, and increased biliary excretion up to 300%. Biliary excretion of polar [(14)C]CH metabolites was not altered by CD. CD pretreatment decreased subcellular distribution of [(14)C]CH equivalents in hepatic cytosol and microsomes and lipoprotein-rich fraction-to-homogenate ratio. CD pretreatment increased the ratio of [(14)C]CH equivalents in high density lipoprotein (HDL) to that in plasma and reduced [(14)C]CH equivalents in the non-HDL fraction 4 h after a bolus lipid dose. CD pretreatment increased plasma non-HDL total CH by 80% 4 h after a bolus lipid dose. Scavenger receptor class B type I (SR-BI) and ATP-binding cassette transporter G8 (ABCG8) proteins were quantified by western blotting in hepatic membranes from control and CD treated mice. Liver membrane contents of SR-BI and ABCG8 proteins were unchanged by CD pretreatment. The data demonstrated that a single dose of CD altered CH homeostasis and lipoprotein metabolism.

  17. Intestinal Farnesoid X Receptor Controls Transintestinal Cholesterol Excretion in Mice

    NARCIS (Netherlands)

    Boer, J.F. de; Schonewille, M.; Boesjes, M.; Wolters, H.; Bloks, V.W.; Bos, T.; Dijk, T.H. van; Jurdzinski, A.; Boverhof, R.; Wolters, J.C.; Kuivenhoven, J.A.; Deursen, J.M.A. van; Elferink, R.P.; Moschetta, A.; Kremoser, C.; Verkade, H.J.; Kuipers, F.; Groen, A.K.

    2017-01-01

    BACKGROUND & AIMS: The role of the intestine in the maintenance of cholesterol homeostasis increasingly is recognized. Fecal excretion of cholesterol is the last step in the atheroprotective reverse cholesterol transport pathway, to which biliary and transintestinal cholesterol excretion (TICE)

  18. In Situ and Real-Time SFG Measurements Revealing Organization and Transport of Cholesterol Analogue 6-Ketocholestanol in a Cell Membrane.

    Science.gov (United States)

    Ma, Sulan; Li, Hongchun; Tian, Kangzhen; Ye, Shuji; Luo, Yi

    2014-02-06

    Cholesterol organization and transport within a cell membrane are essential for human health and many cellular functions yet remain elusive so far. Using cholesterol analogue 6-ketocholestanol (6-KC) as a model, we have successfully exploited sum frequency generation vibrational spectroscopy (SFG-VS) to track the organization and transport of cholesterol in a membrane by combining achiral-sensitive ssp (ppp) and chiral-sensitive psp polarization measurements. It is found that 6-KC molecules are aligned at the outer leaflet of the DMPC lipid bilayer with a tilt angle of about 10°. 6-KC organizes itself by forming an α-β structure at low 6-KC concentration and most likely a β-β structure at high 6-KC concentration. Among all proposed models, our results favor the so-called umbrella model with formation of a 6-KC cluster. Moreover, we have found that the long anticipated flip-flop motion of 6-KC in the membrane takes time to occur, at least much longer than previously thought. All of these interesting findings indicate that it is critical to explore in situ, real-time, and label-free methodologies to obtain a precise molecular description of cholesterol's behavior in membranes. This study represents the first application of SFG to reveal the cholesterol-lipid interaction mechanism at the molecular level.

  19. Cholesterol depletion induces dynamic confinement of the G-protein coupled serotonin(1A) receptor in the plasma membrane of living cells.

    Science.gov (United States)

    Pucadyil, Thomas J; Chattopadhyay, Amitabha

    2007-03-01

    Cholesterol is an essential constituent of eukaryotic membranes and plays a crucial role in membrane organization, dynamics, function, and sorting. It is often found distributed non-randomly in domains or pools in biological and model membranes and is thought to contribute to a segregated distribution of membrane constituents. Signal transduction events mediated by seven transmembrane domain G-protein coupled receptors (GPCRs) are the primary means by which cells communicate with and respond to their external environment. We analyzed the role of cholesterol in the plasma membrane organization of the G-protein coupled serotonin(1A) receptor by fluorescence recovery after photobleaching (FRAP) measurements with varying bleach spot sizes. Our results show that lateral diffusion parameters of serotonin(1A) receptors in normal cells are consistent with models describing diffusion of molecules in a homogenous membrane. Interestingly, these characteristics are altered in cholesterol-depleted cells in a manner that is consistent with dynamic confinement of serotonin(1A) receptors in the plasma membrane. Importantly, analysis of ligand binding and downstream signaling of the serotonin(1A) receptor suggests that receptor function is affected in a significantly different manner when intact cells or isolated membranes are depleted of cholesterol. These results assume significance in the context of interpreting effects of cholesterol depletion on diffusion characteristics of membrane proteins in particular, and cholesterol-dependent cellular processes in general.

  20. Effect of growth hormone replacement therapy on plasma lecithin : cholesterol acyltransferase and lipid transfer protein activities in growth hormone-deficient adults

    NARCIS (Netherlands)

    Beentjes, JAM; van Tol, A; Sluiter, WJ; Dullaart, RPF

    The effects of growth hormone (GH) replacement on plasma lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP), and phospholipid transfer protein (PLTP), factors involved in high density lipoprotein (HDL) metabolism, We unknown. We carried out a 6 mouths study in 24

  1. Tritium Suicide Selection Identifies Proteins Involved in the Uptake and Intracellular Transport of Sterols in Saccharomyces cerevisiae▿

    Science.gov (United States)

    Sullivan, David P.; Georgiev, Alexander; Menon, Anant K.

    2009-01-01

    Sterol transport between the plasma membrane (PM) and the endoplasmic reticulum (ER) occurs by a nonvesicular mechanism that is poorly understood. To identify proteins required for this process, we isolated Saccharomyces cerevisiae mutants with defects in sterol transport. We used Upc2-1 cells that have the ability to take up sterols under aerobic conditions and exploited the observation that intracellular accumulation of exogenously supplied [3H]cholesterol in the form of [3H]cholesteryl ester requires an intact PM-ER sterol transport pathway. Upc2-1 cells were mutagenized using a transposon library, incubated with [3H]cholesterol, and subjected to tritium suicide selection to isolate mutants with a decreased ability to accumulate [3H]cholesterol. Many of the mutants had defects in the expression and trafficking of Aus1 and Pdr11, PM-localized ABC transporters that are required for sterol uptake. Through characterization of one of the mutants, a new role was uncovered for the transcription factor Mot3 in controlling expression of Aus1 and Pdr11. A number of mutants had transposon insertions in the uncharacterized Ydr051c gene, which we now refer to as DET1 (decreased ergosterol transport). These mutants expressed Aus1 and Pdr11 normally but were severely defective in the ability to accumulate exogenously supplied cholesterol. The transport of newly synthesized sterols from the ER to the PM was also defective in det1Δ cells. These data indicate that the cytoplasmic protein encoded by DET1 is involved in intracellular sterol transport. PMID:19060182

  2. High pressure modulated transport and signaling functions of membrane proteins in models and in vivo

    International Nuclear Information System (INIS)

    Vogel, R F; Linke, K; Teichert, H; Ehrmann, M A

    2008-01-01

    Cellular membranes serve in the separation of compartments, recognition of the environment, selective transport and signal transduction. Membrane lipids and membrane proteins play distinct roles in these processes, which are affected by environmental chemical (e. g. pH) or physical (e. g. pressure and temperature) changes. High hydrostatic pressure (HHP) affects fluidity and integrity of bacterial membranes instantly during the ramp, resulting in a loss of membrane potential and vital membrane protein functions. We have used the multiple drug transporter LmrA from Lactococcus lactis and ToxR, a membrane protein sensor from Photobacterium profundum, a deep-sea bacterium, and Vibrio cholerae to study membrane protein interaction and functionality in proteolioposomes and by the use of in vivo reporter systems, respectively. Both proteins require dimerization in the phospholipid bilayer for their functionality, which was favoured in the liquid crystalline lipid phase with ToxR and LmrA. Whereas LmrA, which resides in liposomes consisting of DMPC, DMPC/cholesterol or natural lipids, lost its ATPase activity above 20 or 40 MPa, it maintained its active dimeric structure in DOPC/DPPC/cholesterol liposomes up to 120 MPa. By using a specific indicator strain in which the dimerisation of ToxR initiates the transcription of lacZ it was demonstrated, that the amino acid sequence of the transmembrane domain influences HHP stability of ToxR dimerization in vivo. Thus, both the lipid structure and the nature of the protein affect membrane protein interaction. It is suggested that the protein structure determines basic functionality, e.g. principle ability or kinetics to dimerize to a functional complex, while the lipid environment modulates this property

  3. High pressure modulated transport and signaling functions of membrane proteins in models and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, R F; Linke, K; Teichert, H; Ehrmann, M A [Technische Universitaet Muenchen, Technische Mikrobiologie, Weihenstephaner Steig 16, 85350 Freising (Germany)], E-mail: rudi.vogel@wzw.tum.de

    2008-07-15

    Cellular membranes serve in the separation of compartments, recognition of the environment, selective transport and signal transduction. Membrane lipids and membrane proteins play distinct roles in these processes, which are affected by environmental chemical (e. g. pH) or physical (e. g. pressure and temperature) changes. High hydrostatic pressure (HHP) affects fluidity and integrity of bacterial membranes instantly during the ramp, resulting in a loss of membrane potential and vital membrane protein functions. We have used the multiple drug transporter LmrA from Lactococcus lactis and ToxR, a membrane protein sensor from Photobacterium profundum, a deep-sea bacterium, and Vibrio cholerae to study membrane protein interaction and functionality in proteolioposomes and by the use of in vivo reporter systems, respectively. Both proteins require dimerization in the phospholipid bilayer for their functionality, which was favoured in the liquid crystalline lipid phase with ToxR and LmrA. Whereas LmrA, which resides in liposomes consisting of DMPC, DMPC/cholesterol or natural lipids, lost its ATPase activity above 20 or 40 MPa, it maintained its active dimeric structure in DOPC/DPPC/cholesterol liposomes up to 120 MPa. By using a specific indicator strain in which the dimerisation of ToxR initiates the transcription of lacZ it was demonstrated, that the amino acid sequence of the transmembrane domain influences HHP stability of ToxR dimerization in vivo. Thus, both the lipid structure and the nature of the protein affect membrane protein interaction. It is suggested that the protein structure determines basic functionality, e.g. principle ability or kinetics to dimerize to a functional complex, while the lipid environment modulates this property.

  4. High pressure modulated transport and signaling functions of membrane proteins in models and in vivo

    Science.gov (United States)

    Vogel, R. F.; Linke, K.; Teichert, H.; Ehrmann, M. A.

    2008-07-01

    Cellular membranes serve in the separation of compartments, recognition of the environment, selective transport and signal transduction. Membrane lipids and membrane proteins play distinct roles in these processes, which are affected by environmental chemical (e. g. pH) or physical (e. g. pressure and temperature) changes. High hydrostatic pressure (HHP) affects fluidity and integrity of bacterial membranes instantly during the ramp, resulting in a loss of membrane potential and vital membrane protein functions. We have used the multiple drug transporter LmrA from Lactococcus lactis and ToxR, a membrane protein sensor from Photobacterium profundum, a deep-sea bacterium, and Vibrio cholerae to study membrane protein interaction and functionality in proteolioposomes and by the use of in vivo reporter systems, respectively. Both proteins require dimerization in the phospholipid bilayer for their functionality, which was favoured in the liquid crystalline lipid phase with ToxR and LmrA. Whereas LmrA, which resides in liposomes consisting of DMPC, DMPC/cholesterol or natural lipids, lost its ATPase activity above 20 or 40 MPa, it maintained its active dimeric structure in DOPC/DPPC/cholesterol liposomes up to 120 MPa. By using a specific indicator strain in which the dimerisation of ToxR initiates the transcription of lacZ it was demonstrated, that the amino acid sequence of the transmembrane domain influences HHP stability of ToxR dimerization in vivo. Thus, both the lipid structure and the nature of the protein affect membrane protein interaction. It is suggested that the protein structure determines basic functionality, e.g. principle ability or kinetics to dimerize to a functional complex, while the lipid environment modulates this property.

  5. Dietary cholesterol induces trafficking of intestinal Niemann-Pick Type C1 Like 1 from the brush border to endosomes

    DEFF Research Database (Denmark)

    Skov, Marianne; Tønnesen, Carina K; Hansen, Gert H

    2011-01-01

    The transmembrane protein Niemann-Pick C1 Like 1 (NPC1L1) belongs to the Niemann-Pick C1 (NPC1) family of cholesterol transporters and is mainly expressed in the liver and the small intestine. NPC1L1 is believed to be the main transporter responsible for the absorption of dietary cholesterol. Lik...

  6. Transintestinal cholesterol excretion in humans

    NARCIS (Netherlands)

    Reeskamp, Laurens F.; Meessen, Emma C. E.; Groen, Albert K.

    2018-01-01

    Purpose of review To discuss recent insights into the measurement and cellular basis of transintestinal cholesterol excretion (TICE) in humans and to explore TICE as a therapeutic target for increasing reverse cholesterol transport. Recent findings TICE is the net effect of cholesterol excretion by

  7. Proteins mediating intra- and intercellular transport of lipids and lipid-modified proteins

    NARCIS (Netherlands)

    Neumann, S.

    2008-01-01

    Proteins mediating intra- and intercellular transport of lipids and lipid-modified proteins In this thesis, I studied the intra- and intercellular transport of lipidic molecules, in particular glycosphingolipids and lipid-modified proteins. The first part focuses on the intracellular transport of

  8. Cholesterol: Its Regulation and Role in Central Nervous System Disorders

    Directory of Open Access Journals (Sweden)

    Matthias Orth

    2012-01-01

    Full Text Available Cholesterol is a major constituent of the human brain, and the brain is the most cholesterol-rich organ. Numerous lipoprotein receptors and apolipoproteins are expressed in the brain. Cholesterol is tightly regulated between the major brain cells and is essential for normal brain development. The metabolism of brain cholesterol differs markedly from that of other tissues. Brain cholesterol is primarily derived by de novo synthesis and the blood brain barrier prevents the uptake of lipoprotein cholesterol from the circulation. Defects in cholesterol metabolism lead to structural and functional central nervous system diseases such as Smith-Lemli-Opitz syndrome, Niemann-Pick type C disease, and Alzheimer’s disease. These diseases affect different metabolic pathways (cholesterol biosynthesis, lipid transport and lipoprotein assembly, apolipoproteins, lipoprotein receptors, and signaling molecules. We review the metabolic pathways of cholesterol in the CNS and its cell-specific and microdomain-specific interaction with other pathways such as the amyloid precursor protein and discuss potential treatment strategies as well as the effects of the widespread use of LDL cholesterol-lowering drugs on brain functions.

  9. Molecular mechanisms of protein-cholesterol interactions in plasma membranes: Functional distinction between topological (tilted) and consensus (CARC/CRAC) domains.

    Science.gov (United States)

    Fantini, Jacques; Di Scala, Coralie; Baier, Carlos J; Barrantes, Francisco J

    2016-09-01

    The molecular mechanisms that control the multiple possible modes of protein association with membrane cholesterol are remarkably convergent. These mechanisms, which include hydrogen bonding, CH-π stacking and dispersion forces, are used by a wide variety of extracellular proteins (e.g. microbial or amyloid) and membrane receptors. Virus fusion peptides penetrate the membrane of host cells with a tilted orientation that is compatible with a transient interaction with cholesterol; this tilted orientation is also characteristic of the process of insertion of amyloid proteins that subsequently form oligomeric pores in the plasma membrane of brain cells. Membrane receptors that are associated with cholesterol generally display linear consensus binding motifs (CARC and CRAC) characterized by a triad of basic (Lys/Arg), aromatic (Tyr/phe) and aliphatic (Leu/Val) amino acid residues. In some cases, the presence of both CARC and CRAC within the same membrane-spanning domain allows the simultaneous binding of two cholesterol molecules, one in each membrane leaflet. In this review the molecular basis and the functional significance of the different modes of protein-cholesterol interactions in plasma membranes are discussed. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. Morphology-Variable Aggregates Prepared from Cholesterol-Containing Amphiphilic Glycopolymers: Their Protein Recognition/Adsorption and Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Zhao Wang

    2018-02-01

    Full Text Available In this study, a series of diblock glycopolymers, poly(6-O-methacryloyl-d-galactopyranose-b-poly(6-cholesteryloxyhexyl methacrylate (PMAgala-b-PMAChols, with cholesterol/galactose grafts were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT polymerization and deprotection process. The glycopolymers could self-assemble into aggregates with various morphologies depending on cholesterol/galactose-containing block weight ratios, as determined by transmission electronic microscopy (TEM and dynamic laser light scattering (DLS. In addition, the lectin (Ricinus communis agglutinin II, RCA120 recognition and bovine serum albumin (BSA adsorption of the PMAgala-b-PMAChol aggregates were evaluated. The SK-Hep-1 tumor cell inhibition properties of the PMAgala-b-PMAChol/doxorubicin (DOX complex aggregates were further examined in vitro. Results indicate that the PMAgala-b-PMAChol aggregates with various morphologies showed different interaction/recognition features with RCA120 and BSA. Spherical aggregates (d ≈ 92 nm possessed the highest RCA120 recognition ability and lowest BSA protein adsorption. In addition, the DOX-loaded spherical complex aggregates exhibited a better tumor cell inhibition property than those of nanofibrous complex aggregates. The morphology-variable aggregates derived from the amphiphilic glycopolymers may serve as multifunctional biomaterials with biomolecular recognition and drug delivery features.

  11. Reduction in C-reactive protein and LDL cholesterol and cardiovascular event rates after initiation of rosuvastatin: a prospective study of the JUPITER trial

    DEFF Research Database (Denmark)

    Ridker, Paul M; Danielson, Eleanor; Fonseca, Francisco Ah

    2009-01-01

    BACKGROUND: Statins lower high-sensitivity C-reactive protein (hsCRP) and cholesterol concentrations, and hypothesis generating analyses suggest that clinical outcomes improve in patients given statins who achieve hsCRP concentrations less than 2 mg/L in addition to LDL cholesterol less than 1.......8 mmol/L (LDL cholesterol and hsCRP after the start of statin therapy is controversial. We prospectively tested this hypothesis. METHODS: In an analysis of 15 548 initially healthy men and women participating in the JUPITER trial (87% of full cohort), we...... to on-treatment concentrations of LDL cholesterol (>/=1.8 mmol/L or /=2 mg/L or

  12. Cholesterol and Health

    Indian Academy of Sciences (India)

    fats and oil in the diet on the other hand. Gallstones result from ... such factors as high levels of estrogens, multiple pregnancies, obesity, genetic factors and certain ... protein with an inner core of cholesterol and triglycerides. Lipoproteins are ...

  13. The levels of plasma low density lipoprotein are independent of cholesterol ester transfer protein in fish-oil fed F1B hamsters

    Directory of Open Access Journals (Sweden)

    Davis Phillip J

    2005-03-01

    Full Text Available Abstract Background Cholesterol ester transfer protein (CETP plays a major role in regulating the levels of LDL- and HDL-cholesterol. We previously observed a fish-oil-induced elevation of low-density lipoprotein (LDL-and very-low-density lipoprotein (VLDL-cholesterol concentrations and a decrease in high-density lipoprotein (HDL-cholesterol concentration in F1B hamsters. The molecular mechanism/s by which fish oil induces hyperlipidaemic effect was investigated in this study. We examined whether the effects of dietary fish oil on plasma lipoprotein concentrations are due to fish-oil-induced alterations in plasma CETP activity. MIX diet, a diet supplemented with a mixture of lard and safflower oil, was used as the control diet. Results We found that fish oil feeding in hamsters reduced CETP mass as well as CETP activity. Increasing the dietary fat level of fish-oil from 5% to 20% (w/w led to a further decrease in CETP mass. Supplementation with dietary cholesterol increased both CETP mass and CETP activity in fish-oil and MIX-diet fed hamsters. However, there was no correlation between CETP mass as well as CETP activity and LDL-cholesterol concentrations. Conclusion These findings suggest that cholesterol ester transfer between HDL and LDL is not likely to play a major role in determining fish-oil-induced changes in LDL- and HDL-cholesterol concentrations in F1B hamsters. A possible role of reduced clearance of LDL-particles as well as dietary fat level and dietary cholesterol dependent changes in LDL-lipid composition have been discussed.

  14. Cholesterol (image)

    Science.gov (United States)

    Cholesterol is a soft, waxy substance that is present in all parts of the body including the ... and obtained from animal products in the diet. Cholesterol is manufactured in the liver and is needed ...

  15. Cholesterol Test

    Science.gov (United States)

    ... artery disease. Other names for a cholesterol test: Lipid profile, Lipid panel What is it used for? If you ... Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998-2017.Cholesterol Test: Overview; 2016 Jan 12 [ ...

  16. Tofacitinib restores the inhibition of reverse cholesterol transport induced by inflammation: understanding the lipid paradox associated with rheumatoid arthritis.

    Science.gov (United States)

    Pérez-Baos, S; Barrasa, J I; Gratal, P; Larrañaga-Vera, A; Prieto-Potin, I; Herrero-Beaumont, G; Largo, R

    2017-09-01

    Patients with active rheumatoid arthritis (RA) have increased cardiovascular mortality, paradoxically associated with reduced circulating lipid levels. The JAK inhibitor tofacitinib ameliorates systemic and joint inflammation in RA with a concomitant increase in serum lipids. We analysed the effect of tofacitinib on the lipid profile of hyperlipidaemic rabbits with chronic arthritis (CA) and on the changes in reverse cholesterol transport (RCT) during chronic inflammation. CA was induced in previously immunized rabbits, fed a high-fat diet, by administering four intra-articular injections of ovalbumin. A group of rabbits received tofacitinib (10 mg·kg -1 ·day -1 ) for 2 weeks. Systemic and synovial inflammation and lipid content were evaluated. For in vitro studies, THP-1-derived macrophages were exposed to high lipid concentrations and then stimulated with IFNγ in the presence or absence of tofacitinib in order to study mediators of RCT. Tofacitinib decreased systemic and synovial inflammation and increased circulating lipid levels. Although it did not modify synovial macrophage density, it reduced the lipid content within synovial macrophages. In foam macrophages in culture, IFNγ further stimulated intracellular lipid accumulation, while the JAK/STAT inhibition provoked by tofacitinib induced lipid release by increasing the levels of cellular liver X receptor α and ATP-binding cassette transporter (ABCA1) synthesis. Active inflammation could be associated with lipid accumulation within macrophages of CA rabbits. JAK inhibition induced lipid release through RCT activation, providing a plausible explanation for the effect of tofacitinib on the lipid profile of RA patients. © 2017 The British Pharmacological Society.

  17. High protein and cholesterol intakes associated with emergence of glucose intolerance in a low-risk Canadian Inuit population.

    Science.gov (United States)

    Sefidbakht, Saghar; Johnson-Down, Louise; Young, T Kue; Egeland, Grace M

    2016-07-01

    The rate of type 2 diabetes mellitus among Inuit is 12·2 % in individuals over 50 years of age, similar to the Canadian prevalence. Given marked dietary transitions in the Arctic, we evaluated the dietary and other correlates of not previously diagnosed glucose intolerance, defined as type 2 diabetes mellitus, impaired fasting glucose or impaired glucose tolerance. Cross-sectional analyses were limited to adults with a completed 2 h oral glucose tolerance test and without pre-existing diabetes. Anthropometric assessments, health and medication usage questionnaires and a 24 h dietary recall were administered. Canadian International Polar Year Inuit Health Survey (2007-2008). Inuit adults (n 777). Glucose intolerance was associated with older age and adiposity. Percentage of energy from protein above the Acceptable Macronutrient Distribution Range of 35 %, compared with intake within the range, was associated with increased odds of glucose intolerance (OR=1·98; 95 % CI 1·09, 3·61) in multivariable analyses. Further, cholesterol intake in the highest three quartiles combined (median exposures of 207, 416 and 778 mg/d, respectively) compared with the lowest quartile (median intake of 81 mg/d) was associated with glucose intolerance (OR=2·15; 95 % CI 1·23, 3·78) in multivariable analyses. Past-day traditional food consumption was borderline protective of glucose intolerance (P=0·054) and high fibre intake was not significantly protective (P=0·08). The results contribute to the existing literature on high protein and cholesterol intakes as they may relate to diabetes risk.

  18. Hepatitis C Virus Replication Depends on Endosomal Cholesterol Homeostasis.

    Science.gov (United States)

    Stoeck, Ina Karen; Lee, Ji-Young; Tabata, Keisuke; Romero-Brey, Inés; Paul, David; Schult, Philipp; Lohmann, Volker; Kaderali, Lars; Bartenschlager, Ralf

    2018-01-01

    Similar to other positive-strand RNA viruses, hepatitis C virus (HCV) causes massive rearrangements of intracellular membranes, resulting in a membranous web (MW) composed of predominantly double-membrane vesicles (DMVs), the presumed sites of RNA replication. DMVs are enriched for cholesterol, but mechanistic details on the source and recruitment of cholesterol to the viral replication organelle are only partially known. Here we focused on selected lipid transfer proteins implicated in direct lipid transfer at various endoplasmic reticulum (ER)-membrane contact sites. RNA interference (RNAi)-mediated knockdown identified several hitherto unknown HCV dependency factors, such as steroidogenic acute regulatory protein-related lipid transfer domain protein 3 (STARD3), oxysterol-binding protein-related protein 1A and -B (OSBPL1A and -B), and Niemann-Pick-type C1 (NPC1), all residing at late endosome and lysosome membranes and required for efficient HCV RNA replication but not for replication of the closely related dengue virus. Focusing on NPC1, we found that knockdown or pharmacological inhibition caused cholesterol entrapment in lysosomal vesicles concomitant with decreased cholesterol abundance at sites containing the viral replicase factor NS5A. In untreated HCV-infected cells, unesterified cholesterol accumulated at the perinuclear region, partially colocalizing with NS5A at DMVs, arguing for NPC1-mediated endosomal cholesterol transport to the viral replication organelle. Consistent with cholesterol being an important structural component of DMVs, reducing NPC1-dependent endosomal cholesterol transport impaired MW integrity. This suggests that HCV usurps lipid transfer proteins, such as NPC1, at ER-late endosome/lysosome membrane contact sites to recruit cholesterol to the viral replication organelle, where it contributes to MW functionality. IMPORTANCE A key feature of the replication of positive-strand RNA viruses is the rearrangement of the host cell

  19. Inhibition of Cholesterol Synthesis in HepG2 Cells by GINST-Decreasing HMG-CoA Reductase Expression Via AMP-Activated Protein Kinase.

    Science.gov (United States)

    Han, Joon-Seung; Sung, Jong Hwan; Lee, Seung Kwon

    2017-11-01

    GINST, a hydrolyzed ginseng extract, has been reported to have antidiabetic effects and to reduce hyperglycemia and hyperlipidemia. Hypercholesterolemia is caused by diet or genetic factors and can lead to atherosclerosis and coronary heart disease. Thus, the purpose of this study is to determine whether GINST and the ginsenoside metabolite, IH-901 (compound K), reduce cholesterol synthesis in HepG2 cells and the signal transduction pathways involved. Concentrations of cholesterol were measured by using an enzymatic method. Expression levels of sterol regulatory element-binding protein 2 (SREBP2), HMG-CoA reductase (HMGCR), peroxisome proliferators-activated receptor γ (PPARγ), CCAAT/enhancer-binding proteins α (C/EBPα), GAPDH, and phosphorylation of AMP-activated protein kinase α (AMPKα), protein kinase B (PKB, also known as Akt), and mechanistic target of rapamycin complex 1 (mTORC1) were measured using western blot. Total cholesterol concentration decreased after GINST treatment for 24 and 48 h. Expression of HMGCR decreased more with GINST than with the inhibitors, U18666A and atorvastatin, after 48 h in a dose-dependent manner. Phosphorylation of AMPKα increased 2.5x by GINST after 360 min of treatment, and phosphorylation of Akt decreased after 120 and 360 min. We separated compound K from GINST extracts flash chromatography. Compound K decreased cholesterol synthesis in HepG2 cells at 24 and 48 h. Therefore, we conclude that GINST inhibits cholesterol synthesis in HepG2 cells by decreasing HMGCR expression via AMPKα activation. GINST, a hydrolyzed ginseng extract, can inhibit cholesterol synthesis in liver cells via activation of AMPKα. IH-901 (compound K), which is the main component with bioactivity in GINST, also has anticholesterol effects. Thus, we suggest that GINST can be used to reduce hypercholesterolemia. © 2017 Institute of Food Technologists®.

  20. C-Reactive Protein Binds to Cholesterol Crystals and Co-Localizes with the Terminal Complement Complex in Human Atherosclerotic Plaques

    DEFF Research Database (Denmark)

    Pilely, Katrine; Fumagalli, Stefano; Rosbjerg, Anne

    2017-01-01

    Inflammation is a part of the initial process leading to atherosclerosis and cholesterol crystals (CC), found in atherosclerotic plaques, which are known to induce complement activation. The pentraxins C-reactive protein (CRP), long pentraxin 3 (PTX3), and serum amyloid P component (SAP) are seru...

  1. Down-regulation of lipid raft-associated onco-proteins via cholesterol-dependent lipid raft internalization in docosahexaenoic acid-induced apoptosis.

    Science.gov (United States)

    Lee, Eun Jeong; Yun, Un-Jung; Koo, Kyung Hee; Sung, Jee Young; Shim, Jaegal; Ye, Sang-Kyu; Hong, Kyeong-Man; Kim, Yong-Nyun

    2014-01-01

    Lipid rafts, plasma membrane microdomains, are important for cell survival signaling and cholesterol is a critical lipid component for lipid raft integrity and function. DHA is known to have poor affinity for cholesterol and it influences lipid rafts. Here, we investigated a mechanism underlying the anti-cancer effects of DHA using a human breast cancer cell line, MDA-MB-231. We found that DHA decreased cell surface levels of lipid rafts via their internalization, which was partially reversed by cholesterol addition. With DHA treatment, caveolin-1, a marker for rafts, and EGFR were colocalized with LAMP-1, a lysosomal marker, in a cholesterol-dependent manner, indicating that DHA induces raft fusion with lysosomes. DHA not only displaced several raft-associated onco-proteins, including EGFR, Hsp90, Akt, and Src, from the rafts but also decreased total levels of those proteins via multiple pathways, including the proteasomal and lysosomal pathways, thereby decreasing their activities. Hsp90 overexpression maintained its client proteins, EGFR and Akt, and attenuated DHA-induced cell death. In addition, overexpression of Akt or constitutively active Akt attenuated DHA-induced apoptosis. All these data indicate that the anti-proliferative effect of DHA is mediated by targeting of lipid rafts via decreasing cell surface lipid rafts by their internalization, thereby decreasing raft-associated onco-proteins via proteasomal and lysosomal pathways and decreasing Hsp90 chaperone function. © 2013.

  2. Mucins and calcium phosphate precipitates additively stimulate cholesterol crystallization

    NARCIS (Netherlands)

    van den Berg, A. A.; van Buul, J. D.; Tytgat, G. N.; Groen, A. K.; Ostrow, J. D.

    1998-01-01

    Human biliary mucin and calcium binding protein (CBP) influence formation of both calcium salt precipitates and cholesterol crystals and colocalize in the center of cholesterol gallstones. We investigated how physiological concentrations of these proteins regulate cholesterol crystallization in

  3. Estimation of Serum Triglycerides, Serum Cholesterol, Total Protein, IgG Levels in Chronic Periodontitis Affected Elderly Patients: A Cross-Sectional Study

    Science.gov (United States)

    Saravanan, A. V.; Ravishankar, P. L.; Kumar, Pradeep; Rajapandian, K.; Kalaivani, V.; Rajula, M. Prem Blaisie

    2017-01-01

    Aim: The present study was conducted to evaluate the serum triglycerides, serum cholesterol, total protein, and IgG levels in elderly patients who were affected by periodontal disease. Materials and Methods: This study was conducted at the Rajah Muthiah Dental College and Hospital in the periodontics division. The study was conducted for a period of 3 months. This study is a prospective analytical study. Sixty individuals who were systemically healthy in the age group of 50 and above were included in this study. Control and experimental groups of 30 participants each were included. Plaque index, gingival index, probing pocket depth, and clinical attachment loss were recorded. Biochemical parameters such as serum cholesterol, serum triglycerides, total protein, and IgG levels were also evaluated and correlated with the periodontal parameters. Data was analyzed using SPSS version 16.0 (IBM Corp., Armonk, NY). The relationship between periodontal status and the biochemical parameters such as serum cholesterol, serum triglycerides, total protein, and IgG levels were evaluated by Student's t-test. Results: There was no significant difference in the plaque and gingival scores between the experimental and control group. It was observed that serum cholesterol level and total protein level was lower in participants suffering from chronic periodontitis. Triglycerides level was significantly elevated in the experimental group. IgG, a level which is not significant, concluded that there is no difference in control and experimental group. Conclusion: It was concluded from the results obtained from the study that there is an association between serum triglycerides, serum cholesterol, total protein, and periodontal disease. However, further longitudinal and well-controlled studies are required to evaluate the relationship between these biochemical parameters and periodontal disease. PMID:28462181

  4. Estimation of Serum Triglycerides, Serum Cholesterol, Total Protein, IgG Levels in Chronic Periodontitis Affected Elderly Patients: A Cross-Sectional Study.

    Science.gov (United States)

    Saravanan, A V; Ravishankar, P L; Kumar, Pradeep; Rajapandian, K; Kalaivani, V; Rajula, M Prem Blaisie

    2017-01-01

    The present study was conducted to evaluate the serum triglycerides, serum cholesterol, total protein, and IgG levels in elderly patients who were affected by periodontal disease. This study was conducted at the Rajah Muthiah Dental College and Hospital in the periodontics division. The study was conducted for a period of 3 months. This study is a prospective analytical study. Sixty individuals who were systemically healthy in the age group of 50 and above were included in this study. Control and experimental groups of 30 participants each were included. Plaque index, gingival index, probing pocket depth, and clinical attachment loss were recorded. Biochemical parameters such as serum cholesterol, serum triglycerides, total protein, and IgG levels were also evaluated and correlated with the periodontal parameters. Data was analyzed using SPSS version 16.0 (IBM Corp., Armonk, NY). The relationship between periodontal status and the biochemical parameters such as serum cholesterol, serum triglycerides, total protein, and IgG levels were evaluated by Student's t-test. There was no significant difference in the plaque and gingival scores between the experimental and control group. It was observed that serum cholesterol level and total protein level was lower in participants suffering from chronic periodontitis. Triglycerides level was significantly elevated in the experimental group. IgG, a level which is not significant, concluded that there is no difference in control and experimental group. It was concluded from the results obtained from the study that there is an association between serum triglycerides, serum cholesterol, total protein, and periodontal disease. However, further longitudinal and well-controlled studies are required to evaluate the relationship between these biochemical parameters and periodontal disease.

  5. Biliary lipid composition and gallstone formation in rabbits fed on soy protein, cholesterol, casein and modified casein.

    OpenAIRE

    Ozben, T

    1989-01-01

    In four experimental groups, rabbits were fed on diets containing soy beans, soy beans plus cholesterol (1%, w/w), casein and modified casein for 8 weeks. Biliary lipid levels, lithogenic-index values and the rate of gallstone formation were determined. The highest mean relative concentrations (mol%) of cholesterol and phospholipid were found in the soy bean + cholesterol group, and the highest mean relative bile acid concentration was in the soy bean group. The lowest mean relative cholester...

  6. Tunneling explains efficient electron transport via protein junctions.

    Science.gov (United States)

    Fereiro, Jerry A; Yu, Xi; Pecht, Israel; Sheves, Mordechai; Cuevas, Juan Carlos; Cahen, David

    2018-05-15

    Metalloproteins, proteins containing a transition metal ion cofactor, are electron transfer agents that perform key functions in cells. Inspired by this fact, electron transport across these proteins has been widely studied in solid-state settings, triggering the interest in examining potential use of proteins as building blocks in bioelectronic devices. Here, we report results of low-temperature (10 K) electron transport measurements via monolayer junctions based on the blue copper protein azurin (Az), which strongly suggest quantum tunneling of electrons as the dominant charge transport mechanism. Specifically, we show that, weakening the protein-electrode coupling by introducing a spacer, one can switch the electron transport from off-resonant to resonant tunneling. This is a consequence of reducing the electrode's perturbation of the Cu(II)-localized electronic state, a pattern that has not been observed before in protein-based junctions. Moreover, we identify vibronic features of the Cu(II) coordination sphere in transport characteristics that show directly the active role of the metal ion in resonance tunneling. Our results illustrate how quantum mechanical effects may dominate electron transport via protein-based junctions.

  7. Association among retinol-binding protein 4, small dense LDL cholesterol and oxidized LDL levels in dyslipidemia subjects.

    Science.gov (United States)

    Wu, Jia; Shi, Yong-hui; Niu, Dong-mei; Li, Han-qing; Zhang, Chun-ni; Wang, Jun-jun

    2012-06-01

    To investigate retinol-binding protein 4 (RBP4), small dense low-density lipoprotein cholesterol (sdLDL-C) and oxidized low-density lipoprotein (ox-LDL) levels and their associations in dyslipidemia subjects. We determined RBP4, sdLDL-C, ox-LDL levels in 150 various dyslipidemia subjects and 50 controls. The correlation analysis and multiple linear regression analysis were performed. The RBP4, sdLDL-C and ox-LDL levels were found increased in various dyslipidemia subjects. The sdLDL-C levels were positively correlated with RBP4 (r=0.273, P=0.001) and ox-LDL (r=0.273, P=0.001). RBP4 levels were also correlated with ox-LDL (r=0.167, P=0.043). The multiple regression analysis showed that only sdLDL-C was a significant independent predictor for RBP4 (β coefficient=0.219, P=0.009; adjusted R(2)=0.041) and ox-LDL (β coefficient=0.253, P=0.003; adjusted R(2)=0.057) levels, respectively. The independent associations of sdLDL-C with RBP4 and ox-LDL were observed in dyslipidemia subjects. RBP4 may play an important role in lipid metabolism of atherosclerosis, particularly in formation of sdLDL. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  8. CER-001, a HDL-mimetic, stimulates the reverse lipid transport and atherosclerosis regression in high cholesterol diet-fed LDL-receptor deficient mice.

    Science.gov (United States)

    Tardy, Claudine; Goffinet, Marine; Boubekeur, Nadia; Ackermann, Rose; Sy, Gavin; Bluteau, Alice; Cholez, Guy; Keyserling, Constance; Lalwani, Narendra; Paolini, John F; Dasseux, Jean-Louis; Barbaras, Ronald; Baron, Rudi

    2014-01-01

    CER-001 is a novel engineered HDL-mimetic comprised of recombinant human apoA-I and phospholipids that was designed to mimic the beneficial properties of nascent pre-β HDL. In this study, we have evaluated the capacity of CER-001 to perform reverse lipid transport in single dose studies as well as to regress atherosclerosis in LDLr(-/-) mice after short-term multiple-dose infusions. CER-001 induced cholesterol efflux from macrophages and exhibited anti-inflammatory response similar to natural HDL. Studies with HUVEC demonstrated CER-001 at a concentration of 500 μg/mL completely suppressed the secretion of cytokines IL-6, IL-8, GM-CSF and MCP-1. Following infusion of CER-001 (10mg/kg) in C57Bl/6J mice, we observed a transient increase in the mobilization of unesterified cholesterol in HDL particles containing recombinant human apoA-I. Finally we show that cholesterol elimination was stimulated in CER-001 treated animals as demonstrated by the increased cholesterol concentration in liver and feces. In a familial hypercholesterolemia mouse model (LDL-receptor deficient mice), the infusion of CER-001 caused 17% and 32% reductions in plaque size, 17% and 23% reductions in lipid content after 5 and 10 doses given every 2 days, respectively. Also, there was an 80% reduction in macrophage content in the plaque following 5 doses, and decreased VCAM-1 expression by 16% and 22% in the plaque following 5 and 10 intravenous doses of CER-001, respectively. These data demonstrate that CER-001 rapidly enhances reverse lipid transport in the mouse, reducing vascular inflammation and promoting regression of diet-induced atherosclerosis in LDLr(-/-) mice upon a short-term multiple dose treatment. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. Cholesterol regulates contractility and inotropic response to β2-adrenoceptor agonist in the mouse atria: Involvement of Gi-protein-Akt-NO-pathway.

    Science.gov (United States)

    Odnoshivkina, Yulia G; Sytchev, Vaycheslav I; Petrov, Alexey M

    2017-06-01

    Majority of cardiac β2-adrenoceptors is located in cholesterol-rich microdomains. Here, we have investigated the underlying mechanisms by which a slight to moderate cholesterol depletion with methyl-β-cyclodextrin (MβCD, 1 and 5mM) interferes with contractility and inotropic effect of β2-adrenergic agonist (fenoterol, 50μM) in the mouse atria. Treatment with MβCD itself increased amplitude of Ca 2+ transient but did not change the contraction amplitude due to a clamping action of elevated NO. Cholesterol depletion significantly attenuated the positive inotropic response to fenoterol which is accompanied by increase in NO generation and decrease in Ca 2+ transient. Influence of 1mM MβCD on the fenoterol-driven changes in both contractility and NO level was strongly attenuated by inhibition of G i -protein (pertussis toxin), Akt (Akt 1/2 kinase inhibitor) or NO-synthase (L-NAME). After exposure to 5mM MβCD, pertussis toxin or Akt inhibitor could recover the β2-agonist effects on contractility, NO production and Ca 2+ transient, while L-NAME only reduced NO level. An adenylyl cyclase activator (forskolin, 50nM) had no influence on the MβCD-induced changes in the β2-agonist effects. Obtained results suggest that slight cholesterol depletion upregulates G i -protein/Akt/NO-synthase signaling that attenuates the positive inotropic response to β2-adrenergic stimulation without altering the Ca 2+ transient. Whilst moderate cholesterol depletion additionally could suppress the enhancement of the Ca 2+ transient amplitude caused by the β2-adrenergic agonist administration in G i -protein/Akt-dependent but NO-independent manner. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Trafficking of cholesterol from cell bodies to distal axons in Niemann Pick C1-deficient neurons.

    Science.gov (United States)

    Karten, Barbara; Vance, Dennis E; Campenot, Robert B; Vance, Jean E

    2003-02-07

    Niemann Pick type C (NPC) disease is a progressive neurodegenerative disorder. In cells lacking functional NPC1 protein, endocytosed cholesterol accumulates in late endosomes/lysosomes. We utilized primary neuronal cultures in which cell bodies and distal axons reside in separate compartments to investigate the requirement of NPC1 protein for transport of cholesterol from cell bodies to distal axons. We have recently observed that in NPC1-deficient neurons compared with wild-type neurons, cholesterol accumulates in cell bodies but is reduced in distal axons (Karten, B., Vance, D. E., Campenot, R. B., and Vance, J. E. (2002) J. Neurochem. 83, 1154-1163). We now show that NPC1 protein is expressed in both cell bodies and distal axons. In NPC1-deficient neurons, cholesterol delivered to cell bodies from low density lipoproteins (LDLs), high density lipoproteins, or cyclodextrin complexes was transported into axons in normal amounts, whereas transport of endogenously synthesized cholesterol was impaired. Inhibition of cholesterol synthesis with pravastatin in wild-type and NPC1-deficient neurons reduced axonal growth. However, LDLs restored a normal rate of growth to wild-type but not NPC1-deficient neurons treated with pravastatin. Thus, although LDL cholesterol is transported into axons of NPC1-deficient neurons, this source of cholesterol does not sustain normal axonal growth. Over the lifespan of NPC1-deficient neurons, these defects in cholesterol transport might be responsible for the observed altered distribution of cholesterol between cell bodies and axons and, consequently, might contribute to the neurological dysfunction in NPC disease.

  11. High blood cholesterol levels

    Science.gov (United States)

    Cholesterol - high; Lipid disorders; Hyperlipoproteinemia; Hyperlipidemia; Dyslipidemia; Hypercholesterolemia ... There are many types of cholesterol. The ones talked about most are: ... lipoprotein (HDL) cholesterol -- often called "good" cholesterol ...

  12. DIETARY FISH OIL-INDUCED CHANGES IN INTRAHEPATIC CHOLESTEROL TRANSPORT AND BILE-ACID SYNTHESIS IN RATS

    NARCIS (Netherlands)

    SMIT, MJ; TEMMERMAN, AM; WOLTERS, H; KUIPERS, F; BEYNEN, AC; VONK, RJ

    Hepatic cholesterol metabolism was studied in rats fed purified diets supplemented (9% wt/wt) with either fish oil (FO) (n-3 fatty acids) or corn oil (CO) (n-6 fatty acids) for 4 wk. Rats were equipped with permanent catheters in heart, bile duct, and duodenum to allow studies under normal feeding

  13. The Ala54Thr Polymorphism of the Fatty Acid Binding Protein 2 Gene Modulates HDL Cholesterol in Mexican-Americans with Type 2 Diabetes

    Directory of Open Access Journals (Sweden)

    Lorena M. Salto

    2015-12-01

    Full Text Available The alanine to threonine amino acid substitution at codon 54 (Ala54Thr of the intestinal fatty acid binding protein (FABP2 has been associated with elevated levels of insulin and blood glucose as well as with dyslipidemia. The aim of this study was to characterize the effect of this FABP2 polymorphism in Mexican-Americans with type 2 diabetes (T2D in the context of a three-month intervention to determine if the polymorphism differentially modulates selected clinical outcomes. For this study, we genotyped 43 participant samples and performed post-hoc outcome analysis of the profile changes in fasting blood glucose, HbA1c, insulin, lipid panel and body composition, stratified by the Ala54Thr polymorphism. Our results show that the Thr54 allele carriers (those who were heterozygous or homozygous for the threonine-encoding allele had lower HDL cholesterol and higher triglyceride levels at baseline compared to the Ala54 homozygotes (those who were homozygous for the alanine-encoding allele. Both groups made clinically important improvements in lipid profiles and glycemic control as a response to the intervention. Whereas the Ala54 homozygotes decreased HDL cholesterol in the context of an overall total cholesterol decrease, Thr54 allele carriers increased HDL cholesterol as part of an overall total cholesterol decrease. We conclude that the Ala54Thr polymorphism of FABP2 modulates HDL cholesterol in Mexican-Americans with T2D and that Thr54 allele carriers may be responsive in interventions that include dietary changes.

  14. Biomimetic materials for protein storage and transport

    Science.gov (United States)

    Firestone, Millicent A [Elmhurst, IL; Laible, Philip D [Villa Park, IL

    2012-05-01

    The invention provides a method for the insertion of protein in storage vehicles and the recovery of the proteins from the vehicles, the method comprising supplying isolated protein; mixing the isolated protein with a fluid so as to form a mixture, the fluid comprising saturated phospholipids, lipopolymers, and a surfactant; cycling the mixture between a first temperature and a second temperature; maintaining the mixture as a solid for an indefinite period of time; diluting the mixture in detergent buffer so as to disrupt the composition of the mixture, and diluting to disrupt the fluid in its low viscosity state for removal of the guest molecules by, for example, dialysis, filtering or chromatography dialyzing/filtering the emulsified solid.

  15. Placenta Copper Transport Proteins in Preeclampsia

    Science.gov (United States)

    Placental insufficiency underlying preeclampsia (PE) is associated with impaired placental angiogenesis. As copper (Cu) is essential to angiogenesis, we investigated differences in the expression of placental Cu transporters Menkes (ATP7A), Wilsons (ATP7B) and the Cu chaperone (CCS) for superoxide d...

  16. Ezetimibe Increases Endogenous Cholesterol Excretion in Humans.

    Science.gov (United States)

    Lin, Xiaobo; Racette, Susan B; Ma, Lina; Wallendorf, Michael; Ostlund, Richard E

    2017-05-01

    Ezetimibe improves cardiovascular outcomes when added to optimum statin treatment. It lowers low-density lipoprotein cholesterol and percent intestinal cholesterol absorption, but the exact cardioprotective mechanism is unknown. We tested the hypothesis that the dominant effect of ezetimibe is to increase the reverse transport of cholesterol from rapidly mixing endogenous cholesterol pool into the stool. In a randomized, placebo-controlled, double-blind parallel trial in 24 healthy subjects with low-density lipoprotein cholesterol 100 to 200 mg/dL, we measured cholesterol metabolism before and after a 6-week treatment period with ezetimibe 10 mg/d or placebo. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d 7 in a lipid emulsion and dietary cholesterol with cholesterol-d 5 and sitostanol-d 4 solubilized in oil. Plasma and stool samples collected during a cholesterol- and phytosterol-controlled metabolic kitchen diet were analyzed by mass spectrometry. Ezetimibe reduced intestinal cholesterol absorption efficiency 30±4.3% (SE, P <0.0001) and low-density lipoprotein cholesterol 19.8±1.9% ( P =0.0001). Body cholesterol pool size was unchanged, but fecal endogenous cholesterol excretion increased 66.6±12.2% ( P <0.0001) and percent cholesterol excretion from body pools into the stool increased 74.7±14.3% ( P <0.0001), whereas plasma cholesterol turnover rose 26.2±3.6% ( P =0.0096). Fecal bile acids were unchanged. Ezetimibe increased the efficiency of reverse cholesterol transport from rapidly mixing plasma and tissue pools into the stool. Further work is needed to examine the potential relation of reverse cholesterol transport and whole body cholesterol metabolism to coronary events and the treatment of atherosclerosis. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01603758. © 2017 American Heart Association, Inc.

  17. Transfer of plasma lipoprotein components and of plasma proteins into aortas of cholesterol-fed rabbits. Molecular size as a determinant of plasma lipoprotein influx

    International Nuclear Information System (INIS)

    Stender, S.; Zilversmit, D.B.

    1981-01-01

    The arterial influx of esterified and free cholesterol from low density lipoproteins and very low density lipoproteins in 20 hypercholesterolemic rabbits was measured simultaneously by the use of lipoproteins labeled in vivo with [ 3 H]- and [ 14 C]-cholesterol. The simultaneous arterial influx of either [ 3 H]-leucine-labeled very low density lipoproteins, low density lipoproteins, high density lipoproteins, or plasma proteins was also measured in each rabbit. The arterial influx was calculated as intimal clearance, i.e., the influx of a given fraction divided by its plasma concentration. The intimal clearance of low density lipoprotein esterified cholesterol was equal to that for the apolipoproteins of that fraction, which is compatible with an arterial influx of intact low density lipoprotein molecules. The intimal clearance of very low density apolipoprotein or cholesteryl ester was less than that for low density lipoprotein, whereas high density lipoprotein and albumin clearances exceeded low density lipoprotein clearance by 1.5- to 3-fold. The intimal clearances of plasma proteins, high density, low density, and very low density lipoproteins decreased linearly with the logarithm of the macromolecular diameter. This indicates that the arterial influx of three plasma lipoprotein fractions and of plasma proteins proceeds by similar mechanisms. Apparently the relative intimal clearances of lipoproteins are more dependent on their size relative to pores or vesicular diameters at the plasma-artery interface than on specific interactions between lipoproteins and the arterial intimal surface

  18. Protein replacement therapy partially corrects the cholesterol-storage phenotype in a mouse model of Niemann-Pick type C2 disease.

    Directory of Open Access Journals (Sweden)

    Gitte Krogh Nielsen

    Full Text Available Niemann-Pick type C2 (NPC2 disease is a fatal autosomal recessive neurovisceral degenerative disorder characterized by late endosomal-lysosomal sequestration of low-density lipoprotein derived cholesterol. The breach in intracellular cholesterol homeostasis is caused by deficiency of functional NPC2, a soluble sterol binding protein targeted to the lysosomes by binding the mannose-6-phosphate receptor. As currently there is no effective treatment for the disorder, we have investigated the efficacy of NPC2 replacement therapy in a murine gene-trap model of NPC2-disease generated on the 129P2/OlaHsd genetic background. NPC2 was purified from bovine milk and its functional competence assured in NPC2-deficient fibroblasts using the specific cholesterol fluorescent probe filipin. For evaluation of phenotype correction in vivo, three-week-old NPC2(-/- mice received two weekly intravenous injections of 5 mg/kg NPC2 until trial termination 66 days later. Whereas the saline treated NPC2(-/- mice exhibited massive visceral cholesterol storage as compared to their wild-type littermates, administration of NPC2 caused a marked reduction in cholesterol build up. The histological findings, indicating an amelioration of the disease pathology in liver, spleen, and lungs, corroborated the biochemical results. Little or no difference in the overall cholesterol levels was observed in the kidneys, blood, cerebral cortex and hippocampus when comparing NPC2(-/- and wild type mice. However, cerebellum cholesterol was increased about two fold in NPC2(-/- mice compared with wild-type littermates. Weight gain performance was slightly improved as a result of the NPC2 treatment but significant motor coordination deficits were still observed. Accordingly, ultrastructural cerebellar abnormalities were detected in both saline treated and NPC2 treated NPC2(-/- animals 87 days post partum. Our data indicate that protein replacement may be a beneficial therapeutic approach in the

  19. Mechanistic logic underlying the axonal transport of cytosolic proteins

    Science.gov (United States)

    Scott, David A.; Das, Utpal; Tang, Yong; Roy, Subhojit

    2011-01-01

    Proteins vital to presynaptic function are synthesized in the neuronal perikarya and delivered into synapses via two modes of axonal transport. While membrane-anchoring proteins are conveyed in fast axonal transport via motor-driven vesicles, cytosolic proteins travel in slow axonal transport; via mechanisms that are poorly understood. We found that in cultured axons, populations of cytosolic proteins tagged to photoactivable-GFP (PA-GFP) move with a slow motor-dependent anterograde bias; distinct from vesicular-trafficking or diffusion of untagged PA-GFP. The overall bias is likely generated by an intricate particle-kinetics involving transient assembly and short-range vectorial spurts. In-vivo biochemical studies reveal that cytosolic proteins are organized into higher-order structures within axon-enriched fractions that are largely segregated from vesicles. Data-driven biophysical modeling best predicts a scenario where soluble molecules dynamically assemble into mobile supra-molecular structures. We propose a model where cytosolic proteins are transported by dynamically assembling into multi-protein complexes that are directly/indirectly conveyed by motors. PMID:21555071

  20. Microvillus-Specific Protein Tyrosine Phosphatase SAP-1 Plays a Role in Regulating the Intestinal Paracellular Transport of Macromolecules.

    Science.gov (United States)

    Mori, Shingo; Kamei, Noriyasu; Murata, Yoji; Takayama, Kozo; Matozaki, Takashi; Takeda-Morishita, Mariko

    2017-09-01

    The stomach cancer-associated protein tyrosine phosphatase 1 (SAP-1) is a receptor-type protein tyrosine phosphatase that is specifically expressed on the apical membrane of the intestinal epithelium. SAP-1 is known to maintain the balance of phosphorylation of proteins together with protein kinases; however, its biological function and impact on pharmacokinetics in the intestine remain unclear. The present study, therefore, aimed at clarifying the relationship between SAP-1 and the intestinal absorption behaviors of typical transporter substrates and macromolecules. The endogenous levels of glucose and total cholesterol in the blood were similar between wild-type and SAP-1-deficient mice (Sap1 -/- ), suggesting no contribution of SAP-1 to biogenic influx. Moreover, in vitro transport study with everted ileal sacs demonstrated that there was no difference in the absorption of breast cancer resistance protein, P-glycoprotein, and peptide transporter substrates between both mice. However, absorptive clearance of macromolecular model dextrans (FD-4 and FD-10) in Sap1 -/- mice was significantly higher than that in wild-type mice, and this was confirmed by the trend of increased FD-4 absorption from colonic loops of Sap1 -/- mice. Therefore, the results of this study suggest the partial contribution of SAP-1 to the regulated transport of hydrophilic macromolecules through paracellular tight junctions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  1. Direct observation of electrogenic NH4(+) transport in ammonium transport (Amt) proteins.

    Science.gov (United States)

    Wacker, Tobias; Garcia-Celma, Juan J; Lewe, Philipp; Andrade, Susana L A

    2014-07-08

    Ammonium transport (Amt) proteins form a ubiquitous family of integral membrane proteins that specifically shuttle ammonium across membranes. In prokaryotes, archaea, and plants, Amts are used as environmental NH4(+) scavengers for uptake and assimilation of nitrogen. In the eukaryotic homologs, the Rhesus proteins, NH4(+)/NH3 transport is used instead in acid-base and pH homeostasis in kidney or NH4(+)/NH3 (and eventually CO2) detoxification in erythrocytes. Crystal structures and variant proteins are available, but the inherent challenges associated with the unambiguous identification of substrate and monitoring of transport events severely inhibit further progress in the field. Here we report a reliable in vitro assay that allows us to quantify the electrogenic capacity of Amt proteins. Using solid-supported membrane (SSM)-based electrophysiology, we have investigated the three Amt orthologs from the euryarchaeon Archaeoglobus fulgidus. Af-Amt1 and Af-Amt3 are electrogenic and transport the ammonium and methylammonium cation with high specificity. Transport is pH-dependent, with a steep decline at pH values of ∼5.0. Despite significant sequence homologies, functional differences between the three proteins became apparent. SSM electrophysiology provides a long-sought-after functional assay for the ubiquitous ammonium transporters.

  2. Cholesterol testing and results

    Science.gov (United States)

    ... your cholesterol is in this normal range. LDL (Bad) Cholesterol LDL cholesterol is sometimes called "bad" cholesterol. ... to 3.3 mmol/l) are desired. VLDL (Bad) Cholesterol VLDL contains the highest amount of triglycerides. ...

  3. What Is Cholesterol?

    Science.gov (United States)

    ... of Cholesterol There are two main types of cholesterol: LDL and HDL. The cholesterol blood test tells how much of each kind you have. Most cholesterol is LDL (low-density lipoprotein) cholesterol. This type is most ...

  4. Cholesterol Facts and Statistics

    Science.gov (United States)

    ... Managing High Cholesterol Cholesterol-lowering Medicine High Cholesterol Statistics and Maps High Cholesterol Facts High Cholesterol Maps ... Deo R, et al. Heart disease and stroke statistics—2017 update: a report from the American Heart ...

  5. Dietary fatty acids regulate hepatic low density lipoprotein (LDL) transport by altering LDL receptor protein and mRNA levels.

    Science.gov (United States)

    Horton, J D; Cuthbert, J A; Spady, D K

    1993-01-01

    The concentration of LDL in plasma is strongly influenced by the amount and the type of lipid in the diet. Recent studies in the hamster have shown that dietary fatty acids differentially affect circulating LDL levels primarily by altering receptor-dependent LDL uptake in the liver. To investigate the mechanistic basis of this effect, rates of receptor-dependent LDL transport in the liver were correlated with LDL receptor protein and mRNA levels in hamsters fed safflower oil or coconut oil and varying amounts of cholesterol. Hepatic LDL receptor activity was significantly lower in animals fed coconut oil than in animals fed safflower oil at all levels of cholesterol intake (26, 53, and 61% lower at cholesterol intakes of 0, 0.06, and 0.12%, respectively). These fatty acid-induced changes in hepatic LDL receptor activity were accompanied by parallel changes in hepatic LDL receptor protein and mRNA levels, suggesting that dietary fatty acids regulate the LDL receptor pathway largely at the mRNA level. Images PMID:8349814

  6. The association of 83 plasma proteins with CHD mortality, BMI, HDL-, and total-cholesterol in men: applying multivariate statistics to identify proteins with prognostic value and biological relevance.

    Science.gov (United States)

    Heidema, A Geert; Thissen, Uwe; Boer, Jolanda M A; Bouwman, Freek G; Feskens, Edith J M; Mariman, Edwin C M

    2009-06-01

    In this study, we applied the multivariate statistical tool Partial Least Squares (PLS) to analyze the relative importance of 83 plasma proteins in relation to coronary heart disease (CHD) mortality and the intermediate end points body mass index, HDL-cholesterol and total cholesterol. From a Dutch monitoring project for cardiovascular disease risk factors, men who died of CHD between initial participation (1987-1991) and end of follow-up (January 1, 2000) (N = 44) and matched controls (N = 44) were selected. Baseline plasma concentrations of proteins were measured by a multiplex immunoassay. With the use of PLS, we identified 15 proteins with prognostic value for CHD mortality and sets of proteins associated with the intermediate end points. Subsequently, sets of proteins and intermediate end points were analyzed together by Principal Components Analysis, indicating that proteins involved in inflammation explained most of the variance, followed by proteins involved in metabolism and proteins associated with total-C. This study is one of the first in which the association of a large number of plasma proteins with CHD mortality and intermediate end points is investigated by applying multivariate statistics, providing insight in the relationships among proteins, intermediate end points and CHD mortality, and a set of proteins with prognostic value.

  7. Position-dependent Effects of Polylysine on Sec Protein Transport*

    Science.gov (United States)

    Liang, Fu-Cheng; Bageshwar, Umesh K.; Musser, Siegfried M.

    2012-01-01

    The bacterial Sec protein translocation system catalyzes the transport of unfolded precursor proteins across the cytoplasmic membrane. Using a recently developed real time fluorescence-based transport assay, the effects of the number and distribution of positive charges on the transport time and transport efficiency of proOmpA were examined. As expected, an increase in the number of lysine residues generally increased transport time and decreased transport efficiency. However, the observed effects were highly dependent on the polylysine position in the mature domain. In addition, a string of consecutive positive charges generally had a more significant effect on transport time and efficiency than separating the charges into two or more charged segments. Thirty positive charges distributed throughout the mature domain resulted in effects similar to 10 consecutive charges near the N terminus of the mature domain. These data support a model in which the local effects of positive charge on the translocation kinetics dominate over total thermodynamic constraints. The rapid translocation kinetics of some highly charged proOmpA mutants suggest that the charge is partially shielded from the electric field gradient during transport, possibly by the co-migration of counter ions. The transport times of precursors with multiple positively charged sequences, or “pause sites,” were fairly well predicted by a local effect model. However, the kinetic profile predicted by this local effect model was not observed. Instead, the transport kinetics observed for precursors with multiple polylysine segments support a model in which translocation through the SecYEG pore is not the rate-limiting step of transport. PMID:22367204

  8. Position-dependent effects of polylysine on Sec protein transport.

    Science.gov (United States)

    Liang, Fu-Cheng; Bageshwar, Umesh K; Musser, Siegfried M

    2012-04-13

    The bacterial Sec protein translocation system catalyzes the transport of unfolded precursor proteins across the cytoplasmic membrane. Using a recently developed real time fluorescence-based transport assay, the effects of the number and distribution of positive charges on the transport time and transport efficiency of proOmpA were examined. As expected, an increase in the number of lysine residues generally increased transport time and decreased transport efficiency. However, the observed effects were highly dependent on the polylysine position in the mature domain. In addition, a string of consecutive positive charges generally had a more significant effect on transport time and efficiency than separating the charges into two or more charged segments. Thirty positive charges distributed throughout the mature domain resulted in effects similar to 10 consecutive charges near the N terminus of the mature domain. These data support a model in which the local effects of positive charge on the translocation kinetics dominate over total thermodynamic constraints. The rapid translocation kinetics of some highly charged proOmpA mutants suggest that the charge is partially shielded from the electric field gradient during transport, possibly by the co-migration of counter ions. The transport times of precursors with multiple positively charged sequences, or "pause sites," were fairly well predicted by a local effect model. However, the kinetic profile predicted by this local effect model was not observed. Instead, the transport kinetics observed for precursors with multiple polylysine segments support a model in which translocation through the SecYEG pore is not the rate-limiting step of transport.

  9. Relationship between circulating microRNA-30c with total- and LDL-cholesterol, their circulatory transportation and effect of statins.

    Science.gov (United States)

    Sodi, Ravinder; Eastwood, Jarlath; Caslake, Muriel; Packard, Chris J; Denby, Laura

    2017-03-01

    Small non-coding microRNAs (miR) have important regulatory roles and are used as biomarkers of disease. We investigated the relationship between lipoproteins and circulating miR-30c, evaluated how they are transported in circulation and determined whether statins altered the circulating concentration of miR-30c. To determine the relationship between lipoproteins and circulating miR-30c, serum samples from 79 subjects recruited from a lipid clinic were evaluated. Ultracentrifugation and nanoparticle tracking analysis was used to evaluate the transportation of miR-30c in the circulation by lipoproteins and extracellular vesicles in three healthy volunteers. Using archived samples from previous studies, the effects of 40mg rosuvastatin (n=22) and 40mg pravastatin (n=24) on miR-30c expression was also examined. RNA extraction, reverse transcription-quantitative real-time polymerase chain reaction was carried out using standard procedures. When stratified according to total cholesterol concentration, there was increased miR-30c expression in the highest compared to the lowest tertile (p=0.035). There was significant positive correlation between miR-30c and total- (r=0.367; p=0.002) and LDL-cholesterol (r=0.391; p=0.001). We found that miR-30c was transported in both exosomes and on HDL3. There was a 3.8-fold increased expression of circulating miR-30c after pravastatin treatment for 1year (p=0.005) but no significant change with atorvastatin after 8weeks (p=0.145). This study shows for the first-time in humans that circulating miR-30c is significantly, positively correlated with total- and LDL-cholesterol implicating regulatory functions in lipid homeostasis. We show miR-30c is transported in both exosomes and on HDL3 and pravastatin therapy significantly increased circulating miR-30c expression adding to the pleiotropic dimensions of statins. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Intestinal cholesterol secretion: future clinical implications

    NARCIS (Netherlands)

    Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

    2013-01-01

    Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

  11. Intestinal cholesterol secretion : future clinical implications

    NARCIS (Netherlands)

    Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

    2013-01-01

    Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

  12. Amphipathic alpha-helices and putative cholesterol binding domains of the influenza virus matrix M1 protein are crucial for virion structure organisation.

    Science.gov (United States)

    Tsfasman, Tatyana; Kost, Vladimir; Markushin, Stanislav; Lotte, Vera; Koptiaeva, Irina; Bogacheva, Elena; Baratova, Ludmila; Radyukhin, Victor

    2015-12-02

    The influenza virus matrix M1 protein is an amphitropic membrane-associated protein, forming the matrix layer immediately beneath the virus raft membrane, thereby ensuring the proper structure of the influenza virion. The objective of this study was to elucidate M1 fine structural characteristics, which determine amphitropic properties and raft membrane activities of the protein, via 3D in silico modelling with subsequent mutational analysis. Computer simulations suggest the amphipathic nature of the M1 α-helices and the existence of putative cholesterol binding (CRAC) motifs on six amphipathic α-helices. Our finding explains for the first time many features of this protein, particularly the amphitropic properties and raft/cholesterol binding potential. To verify these results, we generated mutants of the A/WSN/33 strain via reverse genetics. The M1 mutations included F32Y in the CRAC of α-helix 2, W45Y and W45F in the CRAC of α-helix 3, Y100S in the CRAC of α-helix 6, M128A and M128S in the CRAC of α-helix 8 and a double L103I/L130I mutation in both a putative cholesterol consensus motif and the nuclear localisation signal. All mutations resulted in viruses with unusual filamentous morphology. Previous experimental data regarding the morphology of M1-gene mutant influenza viruses can now be explained in structural terms and are consistent with the pivotal role of the CRAC-domains and amphipathic α-helices in M1-lipid interactions. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Some changes of cholesterol, glucose and total proteins in serum of chicken after effect of low dose of ionizing irradiation

    International Nuclear Information System (INIS)

    Danova, D.; Novakova, J.; Benova, K.; Falis, M.; Sezstakova, E.; Toropila, M.

    2006-01-01

    The aim of investigate was the effect of low-dose ionizing irradiation on the organism of chicken. We investigated changes of concentration of cholesterol and triacylglycerols in time gap 1, 3, 14 and 25 days after expose with a single whole-body gamma irradiation of 3 Gy. (authors)

  14. Sensitivity to lysosome-dependent cell death is directly regulated by lysosomal cholesterol content.

    Directory of Open Access Journals (Sweden)

    Hanna Appelqvist

    Full Text Available Alterations in lipid homeostasis are implicated in several neurodegenerative diseases, although the mechanisms responsible are poorly understood. We evaluated the impact of cholesterol accumulation, induced by U18666A, quinacrine or mutations in the cholesterol transporting Niemann-Pick disease type C1 (NPC1 protein, on lysosomal stability and sensitivity to lysosome-mediated cell death. We found that neurons with lysosomal cholesterol accumulation were protected from oxidative stress-induced apoptosis. In addition, human fibroblasts with cholesterol-loaded lysosomes showed higher lysosomal membrane stability than controls. Previous studies have shown that cholesterol accumulation is accompanied by the storage of lipids such as sphingomyelin, glycosphingolipids and sphingosine and an up regulation of lysosomal associated membrane protein-2 (LAMP-2, which may also influence lysosomal stability. However, in this study the use of myriocin and LAMP deficient fibroblasts excluded these factors as responsible for the rescuing effect and instead suggested that primarily lysosomal cholesterol content determineD the cellular sensitivity to toxic insults. Further strengthening this concept, depletion of cholesterol using methyl-β-cyclodextrin or 25-hydroxycholesterol decreased the stability of lysosomes and cells became more prone to undergo apoptosis. In conclusion, cholesterol content regulated lysosomal membrane permeabilization and thereby influenced cell death sensitivity. Our data suggests that lysosomal cholesterol modulation might be used as a therapeutic strategy for conditions associated with accelerated or repressed apoptosis.

  15. STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC.

    Science.gov (United States)

    Garbarino, Jeanne; Pan, Meihui; Chin, Harvey F; Lund, Frederik W; Maxfield, Frederick R; Breslow, Jan L

    2012-12-01

    STARD4, a member of the evolutionarily conserved START gene family, has been implicated in the nonvesicular intracellular transport of cholesterol. However, the direction of transport and the membranes with which this protein interacts are not clear. We present studies of STARD4 function using small hairpin RNA knockdown technology to reduce STARD4 expression in HepG2 cells. In a cholesterol-poor environment, we found that a reduction in STARD4 expression leads to retention of cholesterol at the plasma membrane, reduction of endoplasmic reticulum-associated cholesterol, and decreased ACAT synthesized cholesteryl esters. Furthermore, D4 KD cells exhibited a reduced rate of sterol transport to the endocytic recycling compartment after cholesterol repletion. Although these cells displayed normal endocytic trafficking in cholesterol-poor and replete conditions, cell surface low density lipoprotein receptor (LDLR) levels were increased and decreased, respectively. We also observed a decrease in NPC1 protein expression, suggesting the induction of compensatory pathways to maintain cholesterol balance. These data indicate a role for STARD4 in nonvesicular transport of cholesterol from the plasma membrane and the endocytic recycling compartment to the endoplasmic reticulum and perhaps other intracellular compartments as well.

  16. Analysis of Cholesterol Trafficking with Fluorescent Probes

    DEFF Research Database (Denmark)

    Maxfield, Frederick R.; Wustner, Daniel

    2012-01-01

    Cholesterol plays an important role in determining the biophysical properties of biological membranes, and its concentration is tightly controlled by homeostatic processes. The intracellular transport of cholesterol among organelles is a key part of the homeostatic mechanism, but sterol transport...... that can bind to cholesterol to reveal its distribution in cells. We also discuss the use of intrinsically fluorescent sterols that closely mimic cholesterol, as well as some minimally modified fluorophore-labeled sterols. Methods for imaging these sterols by conventional fluorescence microscopy...... and by multiphoton microscopy are described. Some label-free methods for imaging cholesterol itself are also discussed briefly....

  17. Multidrug and toxin extrusion proteins as transporters of antimicrobial drugs.

    Science.gov (United States)

    Nies, Anne T; Damme, Katja; Schaeffeler, Elke; Schwab, Matthias

    2012-12-01

    Antimicrobial drugs are essential in the treatment of infectious diseases. A better understanding of transport processes involved in drug disposition will improve the predictability of drug-drug interactions with consequences for drug response. Multidrug And Toxin Extrusion (MATE; SLC47A) proteins are efflux transporters mediating the excretion of several antimicrobial drugs as well as other organic compounds into bile and urine, thereby contributing to drug disposition. This review summarizes current knowledge of the structural and molecular features of human MATE transporters including their functional role in drug transport with a specific focus on antimicrobial drugs. The PubMed database was searched using the terms "MATE1," "MATE-2K," "MATE2," "SLC47A1," "SLC47A2," and "toxin extrusion protein" (up to June 2012). MATE proteins have been recognized as important transporters mediating the final excretion step of cationic drugs into bile and urine. These include the antiviral drugs acyclovir, amprenavir, and ganciclovir, the antibiotics cephalexin, cephradine and levofloxacin, as well as the antimalarial agents chloroquine and quinine. It is therefore important to enhance our understanding of the role of MATEs in drug extrusion with particular emphasis on the functional consequences of genetic variants on disposition of these antimicrobial drugs.

  18. JTT-130, a microsomal triglyceride transfer protein (MTP inhibitor lowers plasma triglycerides and LDL cholesterol concentrations without increasing hepatic triglycerides in guinea pigs

    Directory of Open Access Journals (Sweden)

    Shrestha Sudeep

    2005-09-01

    Full Text Available Abstract Background Microsomal transfer protein inhibitors (MTPi have the potential to be used as a drug to lower plasma lipids, mainly plasma triglycerides (TG. However, studies with animal models have indicated that MTPi treatment results in the accumulation of hepatic TG. The purpose of this study was to evaluate whether JTT-130, a unique MTPi, targeted to the intestine, would effectively reduce plasma lipids without inducing a fatty liver. Methods Male guinea pigs (n = 10 per group were used for this experiment. Initially all guinea pigs were fed a hypercholesterolemic diet containing 0.08 g/100 g dietary cholesterol for 3 wk. After this period, animals were randomly assigned to diets containing 0 (control, 0.0005 or 0.0015 g/100 g of MTPi for 4 wk. A diet containing 0.05 g/100 g of atorvastatin, an HMG-CoA reductase inhibitor was used as the positive control. At the end of the 7th week, guinea pigs were sacrificed to assess drug effects on plasma and hepatic lipids, composition of LDL and VLDL, hepatic cholesterol and lipoprotein metabolism. Results Plasma LDL cholesterol and TG were 25 and 30% lower in guinea pigs treated with MTPi compared to controls (P Conclusion These results suggest that JTT-130 could have potential clinical applications due to its plasma lipid lowering effects with no alterations in hepatic lipid concentrations.

  19. Study of the transport of mercurial compounds by seric proteins

    International Nuclear Information System (INIS)

    Jullien-Saint Guily, Nicole

    1970-01-01

    A bond between the seric proteins and various mercurial compounds labeled with the radioisotopes 203 Hg and 197 Hg was demonstrated by means of research methods specific to radioactivity combined with protein separation techniques. In the course of this study it was shown how strongly the composition of the buffer during electrophoretic migration influences the transport of certain organo-mercurial compounds by the seric proteins. By means of a thioloprive: N - ethyl - maleimide, labeled with 14 C, it was proved that the bonding sites between the proteins and the mercurial compounds were the thiol groups of the proteins but that other bonding sites, in particular the amino groups, could also be involved. (author) [fr

  20. Rab proteins: The key regulators of intracellular vesicle transport

    International Nuclear Information System (INIS)

    Bhuin, Tanmay; Roy, Jagat Kumar

    2014-01-01

    Vesicular/membrane trafficking essentially regulates the compartmentalization and abundance of proteins within the cells and contributes in many signalling pathways. This membrane transport in eukaryotic cells is a complex process regulated by a large and diverse array of proteins. A large group of monomeric small GTPases; the Rabs are essential components of this membrane trafficking route. Most of the Rabs are ubiquitously expressed proteins and have been implicated in vesicle formation, vesicle motility/delivery along cytoskeleton elements and docking/fusion at target membranes through the recruitment of effectors. Functional impairments of Rabs affecting transport pathways manifest different diseases. Rab functions are accompanied by cyclical activation and inactivation of GTP-bound and GDP-bound forms between the cytosol and membranes which is regulated by upstream regulators. Rab proteins are characterized by their distinct sub-cellular localization and regulate a wide variety of endocytic, transcytic and exocytic transport pathways. Mutations of Rabs affect cell growth, motility and other biological processes. - Highlights: • Rab proteins regulate different signalling pathways. • Deregulation of Rabs is the fundamental causes of a variety of human diseases. • This paper gives potential directions in developing therapeutic targets. • This paper also gives ample directions for modulating pathways central to normal physiology. • These are the huge challenges for drug discovery and delivery in near future

  1. Rab proteins: The key regulators of intracellular vesicle transport

    Energy Technology Data Exchange (ETDEWEB)

    Bhuin, Tanmay [Cell and Developmental Biology Unit, Department of Zoology, The University of Burdwan, Golapbag 713104 (India); Roy, Jagat Kumar, E-mail: jkroy@bhu.ac.in [Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi 221005 (India)

    2014-10-15

    Vesicular/membrane trafficking essentially regulates the compartmentalization and abundance of proteins within the cells and contributes in many signalling pathways. This membrane transport in eukaryotic cells is a complex process regulated by a large and diverse array of proteins. A large group of monomeric small GTPases; the Rabs are essential components of this membrane trafficking route. Most of the Rabs are ubiquitously expressed proteins and have been implicated in vesicle formation, vesicle motility/delivery along cytoskeleton elements and docking/fusion at target membranes through the recruitment of effectors. Functional impairments of Rabs affecting transport pathways manifest different diseases. Rab functions are accompanied by cyclical activation and inactivation of GTP-bound and GDP-bound forms between the cytosol and membranes which is regulated by upstream regulators. Rab proteins are characterized by their distinct sub-cellular localization and regulate a wide variety of endocytic, transcytic and exocytic transport pathways. Mutations of Rabs affect cell growth, motility and other biological processes. - Highlights: • Rab proteins regulate different signalling pathways. • Deregulation of Rabs is the fundamental causes of a variety of human diseases. • This paper gives potential directions in developing therapeutic targets. • This paper also gives ample directions for modulating pathways central to normal physiology. • These are the huge challenges for drug discovery and delivery in near future.

  2. Intracellular Transport and Kinesin Superfamily Proteins: Structure, Function and Dynamics

    Science.gov (United States)

    Hirokawa, N.; Takemura, R.

    Using various molecular cell biological and molecular genetic approaches, we identified kinesin superfamily proteins (KIFs) and characterized their significant functions in intracellular transport, which is fundamental for cellular morphogenesis, functioning, and survival. We showed that KIFs not only transport various membranous organelles, proteins complexes and mRNAs fundamental for cellular functions but also play significant roles in higher brain functions such as memory and learning, determination of important developmental processes such as left-right asymmetry formation and brain wiring. We also elucidated that KIFs recognize and bind to their specific cargoes using scaffolding or adaptor protein complexes. Concerning the mechanism of motility, we discovered the simplest unique monomeric motor KIF1A and determined by molecular biophysics, cryoelectron microscopy and X-ray crystallography that KIF1A can move on a microtubule processively as a monomer by biased Brownian motion and by hydolyzing ATP.

  3. Effect of Atorvastatin on Serum Levels of Total Cholesterol and High-Sensitivity C-reactive Protein in High-Risk Patients with Atrial Fibrillation in Asia.

    Science.gov (United States)

    Shi, Ming Yu; Xue, Feng Hua; Teng, Shi Chao; Jiang, Li; Zhu, Jing; Yin, Feng; Gu, Hong Yue

    2015-08-01

    The aim of this meta-analysis was to investigate the effects of atorvastatin on serum levels of high-sensitivity C-reactive protein (hs-CRP) and total cholesterol in atrial fibrillation (AF) patients in Asia. By searching English and Chinese language-based electronic databases (ie, PubMed, EBSCO, Ovid, SpringerLink, Wiley, Web of Science, Wanfang database, China National Knowledge Infrastructure, and VIP database), we identified 13 studies relevant to our topic of interest. Data were collected from the 13 studies and analyzed with Comprehensive Meta-Analysis software (version 2.0, Biostat Inc., Englewood, New Jersey). Initially, our database searches retrieved 356 studies (45 in English, 311 in Chinese). Thirteen studies were selected for the meta-analysis following stringent criteria. The data included 1239 patients with AF, of whom 634 were treated with atorvastatin and included in the treatment group, and 605 patients were treated with conventional treatment and included in the control group. The results of our meta-analysis suggested that the serum levels of hs-CRP (mg/L) and total cholesterol (mmol/L) in the treatment group were significantly lower than those of the control group (hs-CRP: standardized mean difference = 0.962; 95% CI, 0.629-1.295, P < 0.001; total cholesterol: standardized mean difference = 1.400; 95% CI, 0.653-2.146, P < 0.001). The findings of this study suggest that atorvastatin may be very effective in decreasing serum levels of hs-CRP and total cholesterol to prevent cardiovascular events. Copyright © 2015 Elsevier HS Journals, Inc. All rights reserved.

  4. Beyond the Cholesterol-Lowering Effect of Soy Protein: A Review of the Effects of Dietary Soy and Its Constituents on Risk Factors for Cardiovascular Disease

    Directory of Open Access Journals (Sweden)

    D. Dan Ramdath

    2017-03-01

    Full Text Available The hypocholesterolemic effect of soy is well-documented and this has led to the regulatory approval of a health claim relating soy protein to a reduced risk of cardiovascular disease (CVD. However, soybeans contain additional components, such as isoflavones, lecithins, saponins and fiber that may improve cardiovascular health through independent mechanisms. This review summarizes the evidence on the cardiovascular benefits of non-protein soy components in relation to known CVD risk factors such as hypertension, hyperglycemia, inflammation, and obesity beyond cholesterol lowering. Overall, the available evidence suggests non-protein soy constituents improve markers of cardiovascular health; however, additional carefully designed studies are required to independently elucidate these effects. Further, work is also needed to clarify the role of isoflavone-metabolizing phenotype and gut microbiota composition on biological effect.

  5. DISP3, a sterol-sensing domain-containing protein that links thyroid hormone action and cholesterol metabolism

    Czech Academy of Sciences Publication Activity Database

    Zíková, Martina; Corlett, Alicia; Bendová, Zdeňka; Pajer, Petr; Bartůněk, Petr

    2009-01-01

    Roč. 23, č. 4 (2009), s. 520-528 ISSN 0888-8809 R&D Projects: GA AV ČR IAA500520705 Grant - others:EC(XE) LSHM-CT-2005-018652 Institutional research plan: CEZ:AV0Z50520514; CEZ:AV0Z50110509 Keywords : thyroid hormone receptor * cholesterol metabolism * sterol-sensing domain Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.257, year: 2009

  6. Myelin-associated proteins labelled by slow axonal transport

    International Nuclear Information System (INIS)

    Giorgi, P.P.; DuBois, H.

    1981-01-01

    This paper deals with the problem of protein metabolism and provides evidence that the neuronal contribution to myelin metabolism may be restricted to lipids only. On the other hand this line of research led to the partial characterization of a group of neuronal proteins probably involved in axo-glial interactions subserving the onset of myelination and the structural maintenance of the mature myelin sheath. Intraocular injection of radioactive amino acids allows the study of the anterograde transport of labelled proteins along retinofugal fibres which are well myelinated. Myelin extracted from the optic nerve and tract under these conditions also contains labelled proteins. Three hypotheses are available to explain this phenomenon. To offer an explanation for this phenomenon the work was planned as follows. a) Characterization of the spatio-temporal pattern of labelling of myelin, in order to define the experimental conditions (survival time and region of the optic pathway to be studied) necessary to obtain maximal labelling. b) Characterization (by gel electrophoresis) of the myelin-associated proteins which become labelled by axonal transport, in order to work on a consistent pattern of labelling. c) Investigation of the possible mechanism responsible for the labelling of myelin-associated proteins. (Auth.)

  7. LDL: The "Bad" Cholesterol

    Science.gov (United States)

    ... There are two main types of cholesterol: LDL (bad) cholesterol and HDL (good) cholesterol: LDL stands for low-density lipoproteins. It is called the "bad" cholesterol because a high LDL level leads to ...

  8. Modelling Transcapillary Transport of Fluid and Proteins in Hemodialysis Patients.

    Directory of Open Access Journals (Sweden)

    Mauro Pietribiasi

    Full Text Available The kinetics of protein transport to and from the vascular compartment play a major role in the determination of fluid balance and plasma refilling during hemodialysis (HD sessions. In this study we propose a whole-body mathematical model describing water and protein shifts across the capillary membrane during HD and compare its output to clinical data while evaluating the impact of choosing specific values for selected parameters.The model follows a two-compartment structure (vascular and interstitial space and is based on balance equations of protein mass and water volume in each compartment. The capillary membrane was described according to the three-pore theory. Two transport parameters, the fractional contribution of large pores (αLP and the total hydraulic conductivity (LpS of the capillary membrane, were estimated from patient data. Changes in the intensity and direction of individual fluid and solute flows through each part of the transport system were analyzed in relation to the choice of different values of small pores radius and fractional conductivity, lymphatic sensitivity to hydraulic pressure, and steady-state interstitial-to-plasma protein concentration ratio.The estimated values of LpS and αLP were respectively 10.0 ± 8.4 mL/min/mmHg (mean ± standard deviation and 0.062 ± 0.041. The model was able to predict with good accuracy the profiles of plasma volume and serum total protein concentration in most of the patients (average root-mean-square deviation < 2% of the measured value.The applied model provides a mechanistic interpretation of fluid transport processes induced by ultrafiltration during HD, using a minimum of tuned parameters and assumptions. The simulated values of individual flows through each kind of pore and lymphatic absorption rate yielded by the model may suggest answers to unsolved questions on the relative impact of these not-measurable quantities on total vascular refilling and fluid balance.

  9. Yarrowia lipolytica vesicle-mediated protein transport pathways

    Directory of Open Access Journals (Sweden)

    Beckerich Jean-Marie

    2007-11-01

    transport shows that 40% of Y. lipolytica proteins are closer to animal ones, whereas they are only 13% in the case of S. cerevisiae. Conclusion These results provide further support for the idea, previously noted about the endoplasmic reticulum translocation pathway, that Y. lipolytica is more representative of vesicular secretion of animals and other fungi than is S. cerevisiae.

  10. Perfringolysin O Theta Toxin as a Tool to Monitor the Distribution and Inhomogeneity of Cholesterol in Cellular Membranes.

    Science.gov (United States)

    Maekawa, Masashi; Yang, Yanbo; Fairn, Gregory D

    2016-03-08

    Cholesterol is an essential structural component of cellular membranes in eukaryotes. Cholesterol in the exofacial leaflet of the plasma membrane is thought to form membrane nanodomains with sphingolipids and specific proteins. Additionally, cholesterol is found in the intracellular membranes of endosomes and has crucial functions in membrane trafficking. Furthermore, cellular cholesterol homeostasis and regulation of de novo synthesis rely on transport via both vesicular and non-vesicular pathways. Thus, the ability to visualize and detect intracellular cholesterol, especially in the plasma membrane, is critical to understanding the complex biology associated with cholesterol and the nanodomains. Perfringolysin O (PFO) theta toxin is one of the toxins secreted by the anaerobic bacteria Clostridium perfringens and this toxin forms pores in the plasma membrane that causes cell lysis. It is well understood that PFO recognizes and binds to cholesterol in the exofacial leaflets of the plasma membrane, and domain 4 of PFO (D4) is sufficient for the binding of cholesterol. Recent studies have taken advantage of this high-affinity cholesterol-binding domain to create a variety of cholesterol biosensors by using a non-toxic PFO or the D4 in isolation. This review highlights the characteristics and usefulness of, and the principal findings related to, these PFO-derived cholesterol biosensors.

  11. Effect of Doublesynch and Estradoublesynch protocols on estrus induction, conception rate, plasma progesterone, protein, and cholesterol profile in anestrus Gir heifers

    Directory of Open Access Journals (Sweden)

    N. J. Chaudhary

    2018-04-01

    Full Text Available Aim: This study aimed to evaluate the efficacy of Doublesynch and Estradoublesynch protocols on estrus induction, conception rates, plasma progesterone, protein, and cholesterol profile in anestrus Gir heifers. Materials and Methods: In this study, 50 pubertal anestrus Gir heifers were selected from the field and farm conditions. The heifers were dewormed (injection ivermectin, 100 mg, s/c and supplemented with minerals and vitamins (injection organic phosphorus 800 mg and injection Vitamin AD3E and Biotin 10 ml i/m and multi-mineral bolus at 1 bolus daily for 7 days. The heifers were randomly divided into three groups: Doublesynch (n=20, Estradoublesynch (n=20, and control (n=10. The animals were monitored for estrus response, estrus interval, behavioral signs, and conception rates after induced/first, second, and third cycle post-treatment. Blood samples were obtained on day 0, day 9, day 12, and on day 12 post-artificial insemination (AI for determination of plasma progesterone, protein, and cholesterol profile. Results: The estrus response rate between Doublesynch and Estradoublesynch protocols was similar between treated heifers (85% and 95%. The interval from the second prostaglandin F2α (PGF2α injection to estrus induction did not differ between the groups (63.87±4.19 vs. 58.27±3.83 h. The conception rates following induced estrus (20% vs. 30%, at the second cycle (23.07% vs. 16.66%, at the third cycle (22.22% vs. 30.00%, and the overall conception rate (45% and 55% within 27.89±5.75 and 26.45±5.48 days were the same across the treatment groups. The mean plasma progesterone concentrations were significantly (p<0.01 higher on day 9 (second PGF2α injection and day 12 post-AI compared to day 0 (first PGF2α injection and the day of fixed-timed artificial insemination. The concentrations were also significantly (p<0.05 higher in conceived than non-conceived heifers on day 9 of treatment and day 12 post-AI in both the protocols. The

  12. Photoaffinity labeling with cholesterol analogues precisely maps a cholesterol-binding site in voltage-dependent anion channel-1.

    Science.gov (United States)

    Budelier, Melissa M; Cheng, Wayland W L; Bergdoll, Lucie; Chen, Zi-Wei; Janetka, James W; Abramson, Jeff; Krishnan, Kathiresan; Mydock-McGrane, Laurel; Covey, Douglas F; Whitelegge, Julian P; Evers, Alex S

    2017-06-02

    Voltage-dependent anion channel-1 (VDAC1) is a highly regulated β-barrel membrane protein that mediates transport of ions and metabolites between the mitochondria and cytosol of the cell. VDAC1 co-purifies with cholesterol and is functionally regulated by cholesterol, among other endogenous lipids. Molecular modeling studies based on NMR observations have suggested five cholesterol-binding sites in VDAC1, but direct experimental evidence for these sites is lacking. Here, to determine the sites of cholesterol binding, we photolabeled purified mouse VDAC1 (mVDAC1) with photoactivatable cholesterol analogues and analyzed the photolabeled sites with both top-down mass spectrometry (MS), and bottom-up MS paired with a clickable, stable isotope-labeled tag, FLI -tag. Using cholesterol analogues with a diazirine in either the 7 position of the steroid ring (LKM38) or the aliphatic tail (KK174), we mapped a binding pocket in mVDAC1 localized to Thr 83 and Glu 73 , respectively. When Glu 73 was mutated to a glutamine, KK174 no longer photolabeled this residue, but instead labeled the nearby Tyr 62 within this same binding pocket. The combination of analytical strategies employed in this work permits detailed molecular mapping of a cholesterol-binding site in a protein, including an orientation of the sterol within the site. Our work raises the interesting possibility that cholesterol-mediated regulation of VDAC1 may be facilitated through a specific binding site at the functionally important Glu 73 residue. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Loss of Subcellular Lipid Transport Due to ARV1 Deficiency Disrupts Organelle Homeostasis and Activates the Unfolded Protein Response*

    Science.gov (United States)

    Shechtman, Caryn F.; Henneberry, Annette L.; Seimon, Tracie A.; Tinkelenberg, Arthur H.; Wilcox, Lisa J.; Lee, Eunjee; Fazlollahi, Mina; Munkacsi, Andrew B.; Bussemaker, Harmen J.; Tabas, Ira; Sturley, Stephen L.

    2011-01-01

    The ARV1-encoded protein mediates sterol transport from the endoplasmic reticulum (ER) to the plasma membrane. Yeast ARV1 mutants accumulate multiple lipids in the ER and are sensitive to pharmacological modulators of both sterol and sphingolipid metabolism. Using fluorescent and electron microscopy, we demonstrate sterol accumulation, subcellular membrane expansion, elevated lipid droplet formation, and vacuolar fragmentation in ARV1 mutants. Motif-based regression analysis of ARV1 deletion transcription profiles indicates activation of Hac1p, an integral component of the unfolded protein response (UPR). Accordingly, we show constitutive splicing of HAC1 transcripts, induction of a UPR reporter, and elevated expression of UPR targets in ARV1 mutants. IRE1, encoding the unfolded protein sensor in the ER lumen, exhibits a lethal genetic interaction with ARV1, indicating a viability requirement for the UPR in cells lacking ARV1. Surprisingly, ARV1 mutants expressing a variant of Ire1p defective in sensing unfolded proteins are viable. Moreover, these strains also exhibit constitutive HAC1 splicing that interacts with DTT-mediated perturbation of protein folding. These data suggest that a component of UPR induction in arv1Δ strains is distinct from protein misfolding. Decreased ARV1 expression in murine macrophages also results in UPR induction, particularly up-regulation of activating transcription factor-4, CHOP (C/EBP homologous protein), and apoptosis. Cholesterol loading or inhibition of cholesterol esterification further elevated CHOP expression in ARV1 knockdown cells. Thus, loss or down-regulation of ARV1 disturbs membrane and lipid homeostasis, resulting in a disruption of ER integrity, one consequence of which is induction of the UPR. PMID:21266578

  14. Association of a cholesteryl ester transfer protein variant (rs1800777) with fat mass, HDL cholesterol levels, and metabolic syndrome.

    Science.gov (United States)

    de Luis, Daniel; Izaola, Olatz; Primo, David; Gomez, Emilia; Lopez, Juan Jose; Ortola, Ana; Aller, Rocio

    2018-04-25

    There is little evidence of the association between CETP SNPs and obesity and/or related metabolic parameters. To analyze the association of the polymorphism rs1800777 of the CETP gene with anthropometric parameters, lipid profile, metabolic syndrome and its components, and adipokine levels in obese subjects without type 2 diabetes mellitus or hypertension. A population of 1005 obese subjects was analyzed. Electrical bioimpedance was performed, and blood pressure, presence of metabolic syndrome, dietary intake, physical activity, and biochemical tests were recorded. Nine hundred and sixty eight patients (96.3%) had the GG genotype, 37 patients the GA genotype (3.7%) (no AA genotype was detected). Fat mass (delta: 4.4±1.1kg; p=0.04), waist circumference (delta: 5.6±2.1cm; p=0.02), and waist to hip ratio (delta: 0.04±0.01cm; p=0.01) were higher in A allele carriers than in non-A allele carriers. HDL cholesterol levels were lower in A allele carriers than in non-A allele carriers (delta: 4.2±1.0mg/dL; p=0.04). In the logistic regression analysis, the GA genotype was associated to an increased risk of central obesity (OR 7.55, 95% CI 1.10-55.70, p=0.02) and low HDL cholesterol levels (OR 2.46, 95% CI 1.23-4.91, p=0.014). The CETP variant at position +82 is associated to lower HDL cholesterol levels, increased fat mass, and central obesity in obese subjects. These results may suggest a potential role of this variant gene in pathophysiology of adipose tissue. Copyright © 2018 SEEN y SED. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. Changes in plasma low-density lipoprotein (LDL)- and high-density lipoprotein cholesterol in hypo- and hyperthyroid patients are related to changes in free thyroxine, not to polymorphisms in LDL receptor or cholesterol ester transfer protein genes

    NARCIS (Netherlands)

    Diekman, M. J.; Anghelescu, N.; Endert, E.; Bakker, O.; Wiersinga, W. M.

    2000-01-01

    Thyroid function disorders lead to changes in lipoprotein metabolism. Both plasma low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) increase in hypothyroidism and decrease in hyperthyroidism. Changes in LDL-C relate to altered clearance of LDL particles

  16. Increased expression of RXRα in dementia: an early harbinger for the cholesterol dyshomeostasis?

    Directory of Open Access Journals (Sweden)

    Katsel Pavel

    2010-09-01

    Full Text Available Abstract Background Cholesterol content of cerebral membranes is tightly regulated by elaborate mechanisms that balance the level of cholesterol synthesis, uptake and efflux. Among the conventional regulatory elements, a recent research focus has been nuclear receptors, a superfamily of ligand-activated transcription factors providing an indispensable regulatory framework in controlling cholesterol metabolism pathway genes. The mechanism of transcriptional regulation by nuclear receptors such as LXRs involves formation of heterodimers with RXRs. LXR/RXR functions as a sensor of cellular cholesterol concentration and mediates cholesterol efflux by inducing the transcription of key cholesterol shuffling vehicles namely, ATP-binding cassette transporter A1 (ABCA1 and ApoE. Results In the absence of quantitative data from humans, the relevance of expression of nuclear receptors and their involvement in cerebral cholesterol homeostasis has remained elusive. In this work, new evidence is provided from direct analysis of human postmortem brain gene and protein expression suggesting that RXRα, a key regulator of cholesterol metabolism is differentially expressed in individuals with dementia. Importantly, RXRα expression showed strong association with ABCA1 and ApoE gene expression, particularly in AD vulnerable regions. Conclusions These findings suggest that LXR/RXR-induced upregulation of ABCA1 and ApoE levels may be the molecular determinants of cholesterol dyshomeostasis and of the accompanying dementia observed in AD.

  17. From blood to gut: Direct secretion of cholesterol via transintestinal cholesterol efflux

    NARCIS (Netherlands)

    Vrins, Carlos L. J.

    2010-01-01

    The reverse cholesterol transport pathway (RCT) is the focus of many cholesterol lowering therapies By way of this pathway, excess cholesterol is collected from peripheral tissues and delivered back to the liver and gastrointestinal tract for excretion from the body For a long time this removal via

  18. Lack of Abcg1 results in decreased plasma HDL cholesterol levels and increased biliary cholesterol secretion in mice fed a high cholesterol diet

    NARCIS (Netherlands)

    Wiersma, Harmen; Nijstad, Niels; de Boer, Jan Freark; Out, Ruud; Hogewerf, Wytse; Van Berkel, Theo J.; Kuipers, Folkert; Tietge, Uwe J. F.

    Objective: The ATP Binding Cassette transporter G1 (ABCG1) has been implicated in cholesterol efflux towards HDL and reverse cholesterol transport (RCT). Biliary cholesterol secretion is considered as an important step in RCT. The aim of the present study was to determine the consequences of Abcg1

  19. Pharmaceutical excipients influence the function of human uptake transporting proteins.

    Science.gov (United States)

    Engel, Anett; Oswald, Stefan; Siegmund, Werner; Keiser, Markus

    2012-09-04

    Although pharmaceutical excipients are supposed to be pharmacologically inactive, solubilizing agents like Cremophor EL have been shown to interact with cytochrome P450 (CYP)-dependent drug metabolism as well as efflux transporters such as P-glycoprotein (ABCB1) and multidrug resistance associated protein 2 (ABCC2). However, knowledge about their influence on the function of uptake transporters important in drug disposition is very limited. In this study we investigated the in vitro influence of polyethylene glycol 400 (PEG), hydroxypropyl-β-cyclodextrin (HPCD), Solutol HS 15 (SOL), and Cremophor EL (CrEL) on the organic anion transporting polypeptides (OATP) 1A2, OATP2B1, OATP1B1, and OATP1B3 and the Na(+)/taurocholate cotransporting polypeptide (NTCP). In stably transfected human embryonic kidney cells we analyzed the competition of the excipients with the uptake of bromosulfophthalein in OATP1B1, OATP1B3, OATP2B1, and NTCP, estrone-3-sulfate (E(3)S) in OATP1A2, OATP1B1, and OATP2B1, estradiol-17β-glucuronide in OATP1B3, and taurocholate (TA) in OATP1A2 and NTCP cells. SOL and CrEL were the most potent inhibitors of all transporters with the strongest effect on OATP1A2, OATP1B3, and OATP2B1 (IC(50) < 0.01%). HPCD also strongly inhibited all transport proteins but only for substrates containing a sterane-backbone. Finally, PEG seems to be a selective and potent modulator of OATP1A2 with IC(50) values of 0.05% (TA) and 0.14% (E(3)S). In conclusion, frequently used solubilizing agents were shown to interact substantially with intestinal and hepatic uptake transporters which should be considered in drug development. However, the clinical relevance of these findings needs to be evaluated in further in vivo studies.

  20. Membrane ion transport in erythrocytes of salt hypertensive Dahl rats and their F2 hybrids: the importance of cholesterol

    Czech Academy of Sciences Publication Activity Database

    Vokurková, Martina; Dobešová, Zdenka; Kuneš, Jaroslav; Zicha, Josef

    2003-01-01

    Roč. 26, č. 5 (2003), s. 397-404 ISSN 0916-9636 R&D Projects: GA ČR GA305/00/1638; GA MŠk LN00A069 Institutional research plan: CEZ:AV0Z5011922 Keywords : ion transport * salt hypertension * plasma lipids Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 2.013, year: 2003

  1. The Effects of Intrauterine Malnutrition on Maternal-Fetal Cholesterol Transport and Fetal Lipid Synthesis in Mice

    NARCIS (Netherlands)

    van Meer, Hester; van Straten, Esther M. E.; Baller, Julius F. W.; van Dijk, Theo H.; Kuipers, Folkert; Verkade, Henkjan J.; Plosch, Torsten

    Intrauterine malnutrition is associated with increased susceptibility to chronic diseases in adulthood. Growth-restricted infants display a less favorable lipid profile already shortly postnatal. Maternal low protein diet (LPD) during gestation is a well-defined model of fetal programming in rodents

  2. Nanoscale Membrane Domain Formation Driven by Cholesterol

    DEFF Research Database (Denmark)

    Javanainen, Matti; Martinez-Seara, Hector; Vattulainen, Ilpo

    2017-01-01

    Biological membranes generate specific functions through compartmentalized regions such as cholesterol-enriched membrane nanodomains that host selected proteins. Despite the biological significance of nanodomains, details on their structure remain elusive. They cannot be observed via microscopic...... dipalmitoylphosphatidylcholine and cholesterol - the "minimal standard" for nanodomain formation. The simulations reveal how cholesterol drives the formation of fluid cholesterol-rich nanodomains hosting hexagonally packed cholesterol-poor lipid nanoclusters, both of which show registration between the membrane leaflets....... The complex nanodomain substructure forms when cholesterol positions itself in the domain boundary region. Here cholesterol can also readily flip-flop across the membrane. Most importantly, replacing cholesterol with a sterol characterized by a less asymmetric ring region impairs the emergence of nanodomains...

  3. Nuclear transport of heat shock proteins in stressed cells

    International Nuclear Information System (INIS)

    Chughtai, Zahoor Saeed

    2001-01-01

    Nuclear import of proteins that are too large to passively enter the nucleus requires soluble factors, energy , and a nuclear localization signal (NLS). Nuclear protein transport can be regulated, and different forms of stress affect nucleocytoplasmic trafficking. As such, import of proteins containing a classical NLS is inhibited in starving yeast cells. In contrast, the heat shock protein hsp70 Ssa4p concentrates in nuclei upon starvation. Nuclear concentration of Ssa4p in starving cells is reversible, and transfer of nutrient-depleted cells to fresh medium induces Ssa4p nuclear export. This export reaction represents an active process that is sensitive to oxidative stress. Upon starvation, the N-terminal domain of Ssa4p mediates Ssa4p nuclear accumulation, and a short hydrophobic sequence, termed Star (for starvation), is sufficient to localize the reporter proteins green fluorescent protein or β-gaIactosidase to nuclei. To determine whether nuclear accumulation of Star-β-galactosidase depends on a specific nuclear carrier, I have analyzed its distribution in mutant yeast strains that carry a deletion of a single β-importin gene. With this assay I have identified Nmd5p as a β-importin required to concentrate Star-β-galactosidase in nuclei of stationary phase cells. (author)

  4. Nuclear transport of heat shock proteins in stressed cells

    Energy Technology Data Exchange (ETDEWEB)

    Chughtai, Zahoor Saeed

    2001-07-01

    Nuclear import of proteins that are too large to passively enter the nucleus requires soluble factors, energy , and a nuclear localization signal (NLS). Nuclear protein transport can be regulated, and different forms of stress affect nucleocytoplasmic trafficking. As such, import of proteins containing a classical NLS is inhibited in starving yeast cells. In contrast, the heat shock protein hsp70 Ssa4p concentrates in nuclei upon starvation. Nuclear concentration of Ssa4p in starving cells is reversible, and transfer of nutrient-depleted cells to fresh medium induces Ssa4p nuclear export. This export reaction represents an active process that is sensitive to oxidative stress. Upon starvation, the N-terminal domain of Ssa4p mediates Ssa4p nuclear accumulation, and a short hydrophobic sequence, termed Star (for starvation), is sufficient to localize the reporter proteins green fluorescent protein or {beta}-gaIactosidase to nuclei. To determine whether nuclear accumulation of Star-{beta}-galactosidase depends on a specific nuclear carrier, I have analyzed its distribution in mutant yeast strains that carry a deletion of a single {beta}-importin gene. With this assay I have identified Nmd5p as a {beta}-importin required to concentrate Star-{beta}-galactosidase in nuclei of stationary phase cells. (author)

  5. Lipid-protein interactions. The leucine transport system of Lactococcus lactis.

    NARCIS (Netherlands)

    Veld, Geertruida Elisabeth in 't

    1992-01-01

    In summary, it is concluded, that a functionally reconstituted leucine transport system of L. lactis is affected by bilayer features in the following order of importance: lipid headgroup (H+-bonding) › acyl chain carbon number (thickness) › cholesterol (fluidity) › acyl chain unsaturation (indirect

  6. Cellular Cholesterol Facilitates the Postentry Replication Cycle of Herpes Simplex Virus 1.

    Science.gov (United States)

    Wudiri, George A; Nicola, Anthony V

    2017-07-15

    initial entry and transport of viral capsids to the nucleus. Viral protein expression, encapsidation of the viral genome, and the release of mature virions were impacted by the reduction of cellular cholesterol. Cholesterol was also critical for cell-to-cell spread of infection. These findings provide new insights into the cholesterol dependence of HSV-1 replication. Copyright © 2017 American Society for Microbiology.

  7. Isoflavone and Protein Constituents of Lactic Acid-Fermented Soy Milk Combine to Prevent Dyslipidemia in Rats Fed a High Cholesterol Diet

    OpenAIRE

    Kobayashi, Maki; Egusa, Shintaro; Fukuda, Mitsuru

    2014-01-01

    A high cholesterol diet induces dyslipidemia. This study investigated whether isoflavone aglycones in lactic acid-fermented soy milk (LFS) improve lipid metabolism in rats fed a high cholesterol diet. Male Sprague-Dawley rats aged seven weeks were fed an AIN-93G diet, a 1% cholesterol diet (a high cholesterol diet), a high-cholesterol diet containing 4% isoflavone extract of LFS (LFS extract diet), a high-cholesterol diet containing 19.4% ethanol-washed LFS (ethanol-washed LFS diet, isoflavon...

  8. Whole Soy Flour Incorporated into a Muffin and Consumed at 2 Doses of Soy Protein Does Not Lower LDL Cholesterol in a Randomized, Double-Blind Controlled Trial of Hypercholesterolemic Adults12

    Science.gov (United States)

    Padhi, Emily MT; Blewett, Heather J; Duncan, Alison M; Guzman, Randolph P; Hawke, Aileen; Seetharaman, Koushik; Tsao, Rong; Wolever, Thomas MS; Ramdath, D Dan

    2015-01-01

    Background: Soy protein may reduce coronary heart disease (CHD) risk by lowering LDL cholesterol, but few studies have assessed whether whole soy flour displays a similar effect. Objective: The aim of this study was to assess the dose effect of whole soy flour incorporated into muffins on plasma LDL cholesterol in hypercholesterolemic adults. Methods: Adults aged 30–70 y (n = 243) with elevated LDL cholesterol (≥3.0 and ≤5.0 mmol/L) were stratified by LDL cholesterol and randomly assigned to consume 2 soy muffins containing 25 g soy protein [high-dose soy (HDS)], 1 soy and 1 wheat muffin containing 12.5 g soy protein and 12.5 g whey protein [low-dose soy (LDS)], or 2 wheat muffins containing 25 g whey protein (control) daily for 6 wk while consuming a self-selected diet. Fasting blood samples were collected at weeks 0, 3, and 6 for analysis of plasma lipids [total, LDL, and HDL cholesterol and triglycerides (TGs)], glucose, insulin, C-reactive protein (CRP), and isoflavones. Blood pressures also were measured. Dietary intake was assessed at weeks 0 and 4 with the use of 3 d food records. Treatment effects were assessed with the use of intention-to-treat analysis with multiple imputation and LDL cholesterol as the primary outcome. Results: In total, 213 (87.6%) participants completed the trial. Participants were primarily Caucasian (83%) and mostly female (63%), with a mean ± SD body mass index (in kg/m2) of 28.0 ± 4.6 and systolic and diastolic blood pressures of 122 ± 16 and 77 ± 11 mm Hg, respectively. Despite a dose-dependent increase in plasma isoflavones (P < 0.001), neither HDS nor LDS had a significant effect on LDL cholesterol compared with control (mean ± SEM changes: control, −0.04 ± 0.05 mmol/L; HDS, 0.01 ± 0.05 mmol/L; and LDS, −0.04 ± 0.06 mmol/L). There were no significant treatment effects on total or HDL cholesterol, TGs, CRP, homeostatic model assessment of insulin resistance, blood pressure, or the Framingham 10-y CHD risk score

  9. Whole Soy Flour Incorporated into a Muffin and Consumed at 2 Doses of Soy Protein Does Not Lower LDL Cholesterol in a Randomized, Double-Blind Controlled Trial of Hypercholesterolemic Adults.

    Science.gov (United States)

    Padhi, Emily Mt; Blewett, Heather J; Duncan, Alison M; Guzman, Randolph P; Hawke, Aileen; Seetharaman, Koushik; Tsao, Rong; Wolever, Thomas Ms; Ramdath, D Dan

    2015-12-01

    Soy protein may reduce coronary heart disease (CHD) risk by lowering LDL cholesterol, but few studies have assessed whether whole soy flour displays a similar effect. The aim of this study was to assess the dose effect of whole soy flour incorporated into muffins on plasma LDL cholesterol in hypercholesterolemic adults. Adults aged 30-70 y (n = 243) with elevated LDL cholesterol (≥3.0 and ≤5.0 mmol/L) were stratified by LDL cholesterol and randomly assigned to consume 2 soy muffins containing 25 g soy protein [high-dose soy (HDS)], 1 soy and 1 wheat muffin containing 12.5 g soy protein and 12.5 g whey protein [low-dose soy (LDS)], or 2 wheat muffins containing 25 g whey protein (control) daily for 6 wk while consuming a self-selected diet. Fasting blood samples were collected at weeks 0, 3, and 6 for analysis of plasma lipids [total, LDL, and HDL cholesterol and triglycerides (TGs)], glucose, insulin, C-reactive protein (CRP), and isoflavones. Blood pressures also were measured. Dietary intake was assessed at weeks 0 and 4 with the use of 3 d food records. Treatment effects were assessed with the use of intention-to-treat analysis with multiple imputation and LDL cholesterol as the primary outcome. In total, 213 (87.6%) participants completed the trial. Participants were primarily Caucasian (83%) and mostly female (63%), with a mean ± SD body mass index (in kg/m2) of 28.0 ± 4.6 and systolic and diastolic blood pressures of 122 ± 16 and 77 ± 11 mm Hg, respectively. Despite a dose-dependent increase in plasma isoflavones (P LDL cholesterol compared with control (mean ± SEM changes: control, -0.04 ± 0.05 mmol/L; HDS, 0.01 ± 0.05 mmol/L; and LDS, -0.04 ± 0.06 mmol/L). There were no significant treatment effects on total or HDL cholesterol, TGs, CRP, homeostatic model assessment of insulin resistance, blood pressure, or the Framingham 10-y CHD risk score. Consuming 12.5 or 25 g protein from defatted soy flour incorporated into muffins does not reduce LDL

  10. Chloroplast Iron Transport Proteins - Function and Impact on Plant Physiology.

    Science.gov (United States)

    López-Millán, Ana F; Duy, Daniela; Philippar, Katrin

    2016-01-01

    Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field.

  11. Effect of soy protein on swine intestinal lipoproteins

    International Nuclear Information System (INIS)

    Ho, H.T.

    1987-01-01

    Hypocholesterolemic effect of soy protein appears to be the result of reduced cholesterol absorption and enhanced cholesterol excretion. The objective of this study is to delineate the underlying mechanism of soy protein effect on cholesterol absorption. At the end of a 5-week soy-protein or casein diet, swine were subjected to cannulation of mesenteric lymph duct under halothane anesthesia. A single dose of 250 μCi [ 14 C]-cholesterol and 10 mCi [ 3 H]-leucine was infused into the upper jejunum two hours after one-fifth of daily food was given. Then lymph was collected hourly for three hours and the lipoprotein fractions were separated by ultracentrifugation. SDS-PAGE (5%) was used to measure the concentrations of individual apoproteins by densitometric scanning. The three-hour lymphatic transport of cholesterol in casein-fed swine was significantly higher than in those fed soy protein. Triglyceride transports were similar in two groups. The [ 3 H]-leucine incorporation study revealed that transport of apo B-48 bore a significant positive relationship to transport of cholesterol in both chylomicron and VLDL fractions of mesenteric lymph. A greater apo B-48 secretion with higher specific activity was probably responsible for the greater transport of cholesterol in chylomicrons in casein-fed swine. On the other hand, the lesser cholesterol transport in chylomicrons in soy protein-fed swine was probably caused by lower apo B-48 secretion. Similarly, the transport of lymph VLDL cholesterol in swine fed casein or soy protein paralleled the amount of accompanying apo B-48. Dietary proteins probably influence the intestinal synthesis of apo B-48 which in turn affects cholesterol transport into the lymphatics

  12. Regulation of dopamine transporter function by protein-protein interactions: new discoveries and methodological challenges

    DEFF Research Database (Denmark)

    Eriksen, Jacob; Jørgensen, Trine Nygaard; Gether, Ulrik

    2010-01-01

    -synaptic neurons. This has led to the identification of a plethora of different kinases, receptors and scaffolding proteins that interact with DAT and hereby either modulate the catalytic activity of the transporter or regulate its trafficking and degradation. Several new tools for studying DAT regulation in live...

  13. Interaction of cholesterol ester transfer protein polymo- rphisms, body mass index, and birth weight with the risk of dyslipidemia in children and adolescents: the CASPIAN-III study

    Directory of Open Access Journals (Sweden)

    Motahar Heidari-Beni

    2015-11-01

    Full Text Available Objective(s: This study aims to investigate joint association between cholesterol ester transfer protein (CETP polymorphisms and body mass index (BMI or birth weight with the risk of dyslipidemia in Iranian children and adolescents. Materials and Methods:This study was conducted as a sub-study of the “school-based nationwide health survey” (CASPIAN-III. We randomly selected 750 samples from the whole blood samples. Real-time PCR and high resolution melt (HRM analysis were performed to determine Taq1B (rs708272 and A373P (rs5880 polymorphisms. Results:Taq1B polymorphism increased HDL-C, and total cholesterol (TC as well as decreased triglyceride and LDL-C concentrations. LDL-C and triglyceride levels were significantly higher and HDL-C and TC levels were significantly lower among those with A373P polymorphism. CT/TT genotype in Taq1B polymorphism showed a protective effect on dyslipidemia (OR= 0.12, 95%CI: 0.07-0.20. G allele of A373P polymorphism increased the risk of dyslipidemia (OR=4.10, 95%CI: 2.14, 7.83 after adjusting the confounders. We observed interactive effects of CETP gene polymorphisms and BMI or birth weight on dyslipidemia. Conclusion:Findings showed Taq1B polymorphism might have a protective effect and A373P polymorphism had deleterious effect on dyslipidemia in Iranian children and adolescents. These associations interacted with BMI and birth weight.

  14. Soy-dairy protein blend and whey protein ingestion after resistance exercise increases amino acid transport and transporter expression in human skeletal muscle

    Science.gov (United States)

    Reidy, P. T.; Walker, D. K.; Dickinson, J. M.; Gundermann, D. M.; Drummond, M. J.; Timmerman, K. L.; Cope, M. B.; Mukherjea, R.; Jennings, K.; Volpi, E.

    2014-01-01

    Increasing amino acid availability (via infusion or ingestion) at rest or postexercise enhances amino acid transport into human skeletal muscle. It is unknown whether alterations in amino acid availability, from ingesting different dietary proteins, can enhance amino acid transport rates and amino acid transporter (AAT) mRNA expression. We hypothesized that the prolonged hyperaminoacidemia from ingesting a blend of proteins with different digestion rates postexercise would enhance amino acid transport into muscle and AAT expression compared with the ingestion of a rapidly digested protein. In a double-blind, randomized clinical trial, we studied 16 young adults at rest and after acute resistance exercise coupled with postexercise (1 h) ingestion of either a (soy-dairy) protein blend or whey protein. Phenylalanine net balance and transport rate into skeletal muscle were measured using stable isotopic methods in combination with femoral arteriovenous blood sampling and muscle biopsies obtained at rest and 3 and 5 h postexercise. Phenylalanine transport into muscle and mRNA expression of select AATs [system L amino acid transporter 1/solute-linked carrier (SLC) 7A5, CD98/SLC3A2, system A amino acid transporter 2/SLC38A2, proton-assisted amino acid transporter 1/SLC36A1, cationic amino acid transporter 1/SLC7A1] increased to a similar extent in both groups (P protein blend resulted in a prolonged and positive net phenylalanine balance during postexercise recovery compared with whey protein (P protein synthesis increased similarly between groups. We conclude that, while both protein sources enhanced postexercise AAT expression, transport into muscle, and myofibrillar protein synthesis, postexercise ingestion of a protein blend results in a slightly prolonged net amino acid balance across the leg compared with whey protein. PMID:24699854

  15. Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation

    Science.gov (United States)

    He, Fengping; Xu, Xin; Yuan, Shuguo; Tan, Liangqiu; Gao, Lingjun; Ma, Shaochun; Zhang, Shebin; Ma, Zhanzhong; Jiang, Wei; Liu, Fenglian; Chen, Baofeng; Zhang, Beibei; Pang, Jungang; Huang, Xiuyan; Weng, Jiaqiang

    2016-08-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia causing high morbidity and mortality. While changing of the cellular calcium homeostasis plays a critical role in AF, the L-type calcium channel α1c protein has suggested as an important regulator of reentrant spiral dynamics and is a major component of AF-related electrical remodeling. Our computational modeling predicted that miRNA-223 may regulate the CACNA1C gene which encodes the cardiac L-type calcium channel α1c subunit. We found that oxidized low-density lipoprotein (ox-LDL) cholesterol significantly up-regulates both the expression of miRNA-223 and L-type calcium channel protein. In contrast, knockdown of miRNA-223 reduced L-type calcium channel protein expression, while genetic knockdown of endogenous miRNA-223 dampened AF vulnerability. Transfection of miRNA-223 by adenovirus-mediated expression enhanced L-type calcium currents and promoted AF in mice while co-injection of a CACNA1C-specific miR-mimic counteracted the effect. Taken together, ox-LDL, as a known factor in AF-associated remodeling, positively regulates miRNA-223 transcription and L-type calcium channel protein expression. Our results implicate a new molecular mechanism for AF in which miRNA-223 can be used as an biomarker of AF rheumatic heart disease.

  16. Dietary Wheat Bran Oil Is Equally as Effective as Rice Bran Oil in Reducing Plasma Cholesterol.

    Science.gov (United States)

    Lei, Lin; Chen, Jingnan; Liu, Yuwei; Wang, Lijun; Zhao, Guohua; Chen, Zhen-Yu

    2018-03-21

    Rice bran oil (RBO) possesses a plasma cholesterol-lowering activity, while effect of wheat bran oil (WBO) on plasma cholesterol remains unknown. The present study compared the cholesterol-lowering activity of WBO with that of RBO in hamsters. Fifty-four male hamsters were divided into seven groups fed either a noncholesterol diet (NCD) or one of six high-cholesterol diets, namely HCD diet (0.2% cholesterol +9.5% lard), HCD+C diet (0.2% cholesterol +9.5% lard +0.5% cholestyramine), WL diet (0.2% cholesterol +4.8% Lard +4.8% WBO), WH diet (0.2% cholesterol +9.5% WBO), RL diet (0.2% cholesterol +4.8% Lard +4.8% RBO), and RH diet (0.2% cholesterol +9.5% RBO). Plasma total cholesterol (TC) in HCD group was 327.4 ± 31.8 mg/dL, while plasma TC in two WBO and two RBO groups was 242.2 ± 20.8, 243.1 ± 31.7, 257.1 ± 16.3, and 243.4 ± 46.0 mg/dL, respectively, leading to a decrease in plasma TC by 22-26% ( P cholesterol-lowering potency was seen between WBO and RBO. Plasma cholesterol-lowering activity of WBO and RBO was accompanied by down-regulation of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase and fatty acid synthase, while up-regulation of cholesterol-7α-hydroxylase. WL, WH, RL, and RH diets increased the fecal excretion of total neutral sterols by 72.8%, 106.9%, 5.4%, and 36.8% ( P cholesterol absorption via down-regulation of intestinal Niemann-Pick C1 like 1 protein, acyl CoA:cholesterol acyltransferase 2, and ATP binding cassette transporter 5. In summary, WBO was equally effective as RBO in decreasing plasma cholesterol in hypercholesterolemia hamsters.

  17. Serotonin transporter (SERT and translocator protein (TSPO expression in the obese ob/ob mouse

    Directory of Open Access Journals (Sweden)

    Santini Ferruccio

    2011-02-01

    Full Text Available Abstract Background An ever growing body of evidences is emerging concerning metabolism hormones, neurotransmitters or stress-related biomarkers as effective modulators of eating behavior and body weight in mammals. The present study sought at examining the density and affinity of two proteins related to neurotransmission and cell metabolism, the serotonin transporter SERT and the cholesterol import-benzodiazepine site TSPO (translocator protein, in a rodent leptin-lacking mutant, the obese ob/ob mouse. Binding studies were thus carried out in brain or peripheral tissues, blood platelets (SERT and kidneys (TSPO, of ob/ob and WT mice supplied with a standard diet, using the selective radiochemical ligands [3H]-paroxetine and [3H]-PK11195. Results We observed comparable SERT number or affinity in brain and platelets of ob/ob and WT mice, whilst a significantly higher [3H]-PK11195 density was reported in the brain of ob/ob animals. TSPO binding parameters were similar in the kidneys of all tested mice. By [3H]-PK11195 autoradiography of coronal hypothalamic-hippocampal sections, an increased TSPO signal was detected in the dentate gyrus (hippocampus and choroids plexus of ob/ob mice, without appreciable changes in the cortex or hypothalamic-thalamic regions. Conclusions These findings show that TSPO expression is up-regulated in cerebral regions of ob/ob leptin-deficient mice, suggesting a role of the translocator protein in leptin-dependent CNS trophism and metabolism. Unchanged SERT in mutant mice is discussed herein in the context of previous literature as the forerunner to a deeper biochemical investigation.

  18. Effect of P/S ratio (0.5 vs 0.9) on hepatic LDL transport at three levels of dietary cholesterol in cynomolgus macaques

    International Nuclear Information System (INIS)

    Hunt, C.E.; Funk, G.M.; Turley, S.D.; Spady, D.K.; Dietschy, J.M.

    1990-01-01

    Interaction between dietary polyunsaturated to saturated (P/S) fatty acid ratio and cholesterol (C) was studied in 6 groups of male cynomolgus macaques fed diets (oleic acid constant) for 72 weeks as follows (C mg/Cal-P/S): (1), 0.06 - 0.5; (2), 0.06-0.9, (3), 0.28-0.5; (4), 0.28-0.9; (5), 2,35-0.5; (6), 2,35-0.9. Plasma C was proportional to dietary C and was affected significantly by P/S in 1 and 2 only. Mean plasma C (mg/dl) at 72 weeks was: (1) 158; (2) 117; (3) 320; (4) 284; (5) 602; (6) 601. LDL-C was significantly higher in (1) than in (2) (90 vs 65 mg/dl). In vivo LDL turnover studies showed that LDL clearance was suppressed by excess dietary C and by saturated fats in low C diets. Receptor-independent clearance was relatively constant. Hepatic LDL transport was determined after injection of 125I-cellobiose-LDL. Hepatic LDL-C uptake was greater in (2) than in (1). LDL-C synthesis was reduced in (4) and (6) compared to (3) and (5), respectively. The authors conclude that (i) hepatic LDL receptor activity is altered by degree of saturation in dietary triglycerides when dietary C is minimal and (ii) saturated triglycerides enhance LDL-C synthesis when dietary C is ample in this model

  19. Scavenger Receptor Class B Type I Mediates Biliary Cholesterol Secretion Independent of ATP-Binding Cassette Transporter g5/g8 in Mice

    NARCIS (Netherlands)

    Wiersma, Harmen; Gatti, Alberto; Nijstad, Niels; Elferink, Ronald P. J. Oude; Kuipers, Folkert; Tietge, Uwe J. F.

    2009-01-01

    Scavenger receptor class B type I (SR-BI) mediates selective uptake of cholesterol from high-density lipoprotein (HDL) particles by the liver and influences biliary cholesterol secretion. However, it is not dear, if this effect is direct or indirect. The aim of this study was to determine the impact

  20. Cholesterol IQ Quiz

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Cholesterol IQ Quiz Updated:Jul 5,2017 Begin the quiz ... What Your Cholesterol Levels Mean Common Misconceptions Cholesterol IQ Quiz • HDL, LDL, and Triglycerides • Causes of High ...

  1. Common Misconceptions about Cholesterol

    Science.gov (United States)

    ... Venous Thromboembolism Aortic Aneurysm More Common Misconceptions about Cholesterol Updated:Jan 29,2018 How much do you ... are some common misconceptions — and the truth. High cholesterol isn’t a concern for children. High cholesterol ...

  2. Urea transporter proteins as targets for small-molecule diuretics.

    Science.gov (United States)

    Esteva-Font, Cristina; Anderson, Marc O; Verkman, Alan S

    2015-02-01

    Conventional diuretics such as furosemide and thiazides target salt transporters in kidney tubules, but urea transporters (UTs) have emerged as alternative targets. UTs are a family of transmembrane channels expressed in a variety of mammalian tissues, in particular the kidney. UT knockout mice and humans with UT mutations exhibit reduced maximal urinary osmolality, demonstrating that UTs are necessary for the concentration of urine. Small-molecule screening has identified potent and selective inhibitors of UT-A, the UT protein expressed in renal tubule epithelial cells, and UT-B, the UT protein expressed in vasa recta endothelial cells. Data from UT knockout mice and from rodents administered UT inhibitors support the diuretic action of UT inhibition. The kidney-specific expression of UT-A1, together with high selectivity of the small-molecule inhibitors, means that off-target effects of such small-molecule drugs should be minimal. This Review summarizes the structure, expression and function of UTs, and looks at the evidence supporting the validity of UTs as targets for the development of salt-sparing diuretics with a unique mechanism of action. UT-targeted inhibitors may be useful alone or in combination with conventional diuretics for therapy of various oedemas and hyponatraemias, potentially including those refractory to treatment with current diuretics.

  3. The dynamin chemical inhibitor dynasore impairs cholesterol trafficking and sterol-sensitive genes transcription in human HeLa cells and macrophages.

    Directory of Open Access Journals (Sweden)

    Emmanuelle Girard

    Full Text Available Intracellular transport of cholesterol contributes to the regulation of cellular cholesterol homeostasis by mechanisms that are yet poorly defined. In this study, we characterized the impact of dynasore, a recently described drug that specifically inhibits the enzymatic activity of dynamin, a GTPase regulating receptor endocytosis and cholesterol trafficking. Dynasore strongly inhibited the uptake of low-density lipoprotein (LDL in HeLa cells, and to a lower extent in human macrophages. In both cell types, dynasore treatment led to the abnormal accumulation of LDL and free cholesterol (FC within the endolysosomal network. The measure of cholesterol esters (CE further showed that the delivery of regulatory cholesterol to the endoplasmic reticulum (ER was deficient. This resulted in the inhibition of the transcriptional control of the three major sterol-sensitive genes, sterol-regulatory element binding protein 2 (SREBP-2, 3-hydroxy-3-methyl-coenzymeA reductase (HMGCoAR, and low-density lipoprotein receptor (LDLR. The sequestration of cholesterol in the endolysosomal compartment impaired both the active and passive cholesterol efflux in HMDM. Our data further illustrate the importance of membrane trafficking in cholesterol homeostasis and validate dynasore as a new pharmacological tool to study the intracellular transport of cholesterol.

  4. Export of recombinant proteins in Escherichia coli using ABC transporter with an attached lipase ABC transporter recognition domain (LARD

    Directory of Open Access Journals (Sweden)

    Moon Yuseok

    2009-01-01

    Full Text Available Abstract Background ATP binding cassette (ABC transporter secretes the protein through inner and outer membranes simultaneously in gram negative bacteria. Thermostable lipase (TliA of Pseudomonas fluorescens SIK W1 is secreted through the ABC transporter. TliA has four glycine-rich repeats (GGXGXD in its C-terminus, which appear in many ABC transporter-secreted proteins. From a homology model of TliA derived from the structure of P. aeruginosa alkaline protease (AprA, lipase ABC transporter domains (LARDs were designed for the secretion of fusion proteins. Results The LARDs included four glycine-rich repeats comprising a β-roll structure, and were added to the C-terminus of test proteins. Either Pro-Gly linker or Factor Xa site was added between fusion proteins and LARDs. We attached different length of LARDs such as LARD0, LARD1 or whole TliA (the longest LARD to three types of proteins; green fluorescent protein (GFP, epidermal growth factor (EGF and cytoplasmic transduction peptide (CTP. These fusion proteins were expressed in Escherichia coli together with ABC transporter of either P. fluorescens or Erwinia chrysanthemi. Export of fusion proteins with the whole TliA through the ABC transporter was evident on the basis of lipase enzymatic activity. Upon supplementation of E. coli with ABC transporter, GFP-LARDs and EGF-LARDs were excreted into the culture supernatant. Conclusion The LARDs or whole TliA were attached to C-termini of model proteins and enabled the export of the model proteins such as GFP and EGF in E. coli supplemented with ABC transporter. These results open the possibility for the extracellular production of recombinant proteins in Pseudomonas using LARDs or TliA as a C-terminal signal sequence.

  5. Identifying the molecular functions of electron transport proteins using radial basis function networks and biochemical properties.

    Science.gov (United States)

    Le, Nguyen-Quoc-Khanh; Nguyen, Trinh-Trung-Duong; Ou, Yu-Yen

    2017-05-01

    The electron transport proteins have an important role in storing and transferring electrons in cellular respiration, which is the most proficient process through which cells gather energy from consumed food. According to the molecular functions, the electron transport chain components could be formed with five complexes with several different electron carriers and functions. Therefore, identifying the molecular functions in the electron transport chain is vital for helping biologists understand the electron transport chain process and energy production in cells. This work includes two phases for discriminating electron transport proteins from transport proteins and classifying categories of five complexes in electron transport proteins. In the first phase, the performances from PSSM with AAIndex feature set were successful in identifying electron transport proteins in transport proteins with achieved sensitivity of 73.2%, specificity of 94.1%, and accuracy of 91.3%, with MCC of 0.64 for independent data set. With the second phase, our method can approach a precise model for identifying of five complexes with different molecular functions in electron transport proteins. The PSSM with AAIndex properties in five complexes achieved MCC of 0.51, 0.47, 0.42, 0.74, and 1.00 for independent data set, respectively. We suggest that our study could be a power model for determining new proteins that belongs into which molecular function of electron transport proteins. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Influence of the membrane environment on cholesterol transfer.

    Science.gov (United States)

    Breidigan, Jeffrey Michael; Krzyzanowski, Natalie; Liu, Yangmingyue; Porcar, Lionel; Perez-Salas, Ursula

    2017-12-01

    Cholesterol, an essential component in biological membranes, is highly unevenly distributed within the cell, with most localized in the plasma membrane while only a small fraction is found in the endoplasmic reticulum, where it is synthesized. Cellular membranes differ in lipid composition and protein content, and these differences can exist across their leaflets too. This thermodynamic landscape that cellular membranes impose on cholesterol is expected to modulate its transport. To uncover the role the membrane environment has on cholesterol inter- and intra-membrane movement, we used time-resolved small angle neutron scattering to study the passive movement of cholesterol between and within membranes with varying degrees of saturation content. We found that cholesterol moves systematically slower as the degree of saturation in the membranes increases, from a palmitoyl oleyl phosphotidylcholine membrane, which is unsaturated, to a dipalmitoylphosphatidylcholine (DPPC) membrane, which is fully saturated. Additionally, we found that the energetic barrier to move cholesterol in these phosphatidylcholine membranes is independent of their relative lipid composition and remains constant for both flip-flop and exchange at ∼100 kJ/mol. Further, by replacing DPPC with the saturated lipid palmitoylsphingomyelin, an abundant saturated lipid of the outer leaflet of the plasma membrane, we found the rates decreased by a factor of two. This finding is in stark contrast with recent molecular dynamic simulations that predict a dramatic slow-down of seven orders of magnitude for cholesterol flipping in membranes with a similar phosphocholine and SM lipid composition. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  7. Multidrug and toxin extrusion proteins mediate cellular transport of cadmium

    International Nuclear Information System (INIS)

    Yang, Hong; Guo, Dong; Obianom, Obinna N.; Su, Tong; Polli, James E.; Shu, Yan

    2017-01-01

    Cadmium (Cd) is an environmentally prevalent toxicant posing increasing risk to human health worldwide. As compared to the extensive research in Cd tissue accumulation, little was known about the elimination of Cd, particularly its toxic form, Cd ion (Cd 2+ ). In this study, we aimed to examine whether Cd 2+ is a substrate of multidrug and toxin extrusion proteins (MATEs) that are important in renal xenobiotic elimination. HEK-293 cells overexpressing the human MATE1 (HEK-hMATE1), human MATE2-K (HEK-hMATE2-K) and mouse Mate1 (HEK-mMate1) were used to study the cellular transport and toxicity of Cd 2+ . The cells overexpressing MATEs showed a 2–4 fold increase of Cd 2+ uptake that could be blocked by the MATE inhibitor cimetidine. A saturable transport profile was observed with the Michaelis-Menten constant (K m ) of 130 ± 15.8 μM for HEK-hMATE1; 139 ± 21.3 μM for HEK-hMATE2-K; and 88.7 ± 13.5 μM for HEK-mMate1, respectively. Cd 2+ could inhibit the uptake of metformin, a substrate of MATE transporters, with the half maximal inhibitory concentration (IC 50 ) of 97.5 ± 6.0 μM, 20.2 ± 2.6 μM, and 49.9 ± 6.9 μM in HEK-hMATE1, HEK-hMATE2-K, and HEK-mMate1 cells, respectively. In addition, hMATE1 could transport preloaded Cd 2+ out of the HEK-hMATE1 cells, thus resulting in a significant decrease of Cd 2+ -induced cytotoxicity. The present study has provided the first evidence supporting that MATEs transport Cd 2+ and may function as cellular elimination machinery in Cd intoxication. - Highlights: • Cadmium is an environmentally prevalent toxicant. • Little was known regarding the elimination and detoxification of cadmium. • Cadmium ion is here demonstrated as a substrate of MATE transporters. • MATEs may function as cellular elimination machinery in cadmium detoxification.

  8. Multidrug and toxin extrusion proteins mediate cellular transport of cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hong; Guo, Dong; Obianom, Obinna N. [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States); Su, Tong [Department of Oral Maxillofacial Surgery, the First Affiliated Hospital, Xiangya Medical School, Central South University, Hunan 410007 (China); Polli, James E. [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States); Shu, Yan, E-mail: yshu@rx.umaryland.edu [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States)

    2017-01-01

    Cadmium (Cd) is an environmentally prevalent toxicant posing increasing risk to human health worldwide. As compared to the extensive research in Cd tissue accumulation, little was known about the elimination of Cd, particularly its toxic form, Cd ion (Cd{sup 2+}). In this study, we aimed to examine whether Cd{sup 2+} is a substrate of multidrug and toxin extrusion proteins (MATEs) that are important in renal xenobiotic elimination. HEK-293 cells overexpressing the human MATE1 (HEK-hMATE1), human MATE2-K (HEK-hMATE2-K) and mouse Mate1 (HEK-mMate1) were used to study the cellular transport and toxicity of Cd{sup 2+}. The cells overexpressing MATEs showed a 2–4 fold increase of Cd{sup 2+} uptake that could be blocked by the MATE inhibitor cimetidine. A saturable transport profile was observed with the Michaelis-Menten constant (K{sub m}) of 130 ± 15.8 μM for HEK-hMATE1; 139 ± 21.3 μM for HEK-hMATE2-K; and 88.7 ± 13.5 μM for HEK-mMate1, respectively. Cd{sup 2+} could inhibit the uptake of metformin, a substrate of MATE transporters, with the half maximal inhibitory concentration (IC{sub 50}) of 97.5 ± 6.0 μM, 20.2 ± 2.6 μM, and 49.9 ± 6.9 μM in HEK-hMATE1, HEK-hMATE2-K, and HEK-mMate1 cells, respectively. In addition, hMATE1 could transport preloaded Cd{sup 2+} out of the HEK-hMATE1 cells, thus resulting in a significant decrease of Cd{sup 2+}-induced cytotoxicity. The present study has provided the first evidence supporting that MATEs transport Cd{sup 2+} and may function as cellular elimination machinery in Cd intoxication. - Highlights: • Cadmium is an environmentally prevalent toxicant. • Little was known regarding the elimination and detoxification of cadmium. • Cadmium ion is here demonstrated as a substrate of MATE transporters. • MATEs may function as cellular elimination machinery in cadmium detoxification.

  9. The national cholesterol education program diet vs a diet lower in carbohydrates and higher in protein and monounsaturated fat: a randomized trial.

    Science.gov (United States)

    Aude, Y Wady; Agatston, Arthur S; Lopez-Jimenez, Francisco; Lieberman, Eric H; Marie Almon; Hansen, Melinda; Rojas, Gerardo; Lamas, Gervasio A; Hennekens, Charles H

    2004-10-25

    In the United States, obesity is a major clinical and public health problem causing diabetes, dyslipidemia, and hypertension, as well as increasing cardiovascular and total mortality. Dietary restrictions of calories and saturated fat are beneficial. However, it remains unclear whether replacement of saturated fat with carbohydrates (as in the US National Cholesterol Education Program [NCEP] diet) or protein and monounsaturated fat (as in our isocaloric modified low-carbohydrate [MLC] diet, which is lower in total carbohydrates but higher in protein, monounsaturated fat, and complex carbohydrates) is optimal. We randomized 60 participants (29 women and 31 men) to the NCEP or the MLC diet and evaluated them every 2 weeks for 12 weeks. They were aged 28 to 71 years (mean age, 44 years in the NCEP and 46 years in the MLC group). A total of 36% of participants from the NCEP group and 35% from the MLC group had a body mass index (calculated as weight in kilograms divided by the square of height in meters) greater than 27. The primary end point was weight loss, and secondary end points were blood lipid levels and waist-to-hip ratio. Weight loss was significantly greater in the MLC (13.6 lb) than in the NCEP group (7.5 lb), a difference of 6.1 lb (P = .02). There were no significant differences between the groups for total, low density, and high-density lipoprotein cholesterol, triglycerides, or the proportion of small, dense low-density lipoprotein particles. There were significantly favorable changes in all lipid levels within the MLC but not within the NCEP group. Waist-to-hip ratio was not significantly reduced between the groups (P = .27), but it significantly decreased within the MLC group (P = .009). Compared with the NCEP diet, the MLC diet, which is lower in total carbohydrates but higher in complex carbohydrates, protein, and monounsaturated fat, caused significantly greater weight loss over 12 weeks. There were no significant differences between the groups in

  10. Binding proteins enhance specific uptake rate by increasing the substrate-transporter encounter rate.

    Science.gov (United States)

    Bosdriesz, Evert; Magnúsdóttir, Stefanía; Bruggeman, Frank J; Teusink, Bas; Molenaar, Douwe

    2015-06-01

    Microorganisms rely on binding-protein assisted, active transport systems to scavenge for scarce nutrients. Several advantages of using binding proteins in such uptake systems have been proposed. However, a systematic, rigorous and quantitative analysis of the function of binding proteins is lacking. By combining knowledge of selection pressure and physiochemical constraints, we derive kinetic, thermodynamic, and stoichiometric properties of binding-protein dependent transport systems that enable a maximal import activity per amount of transporter. Under the hypothesis that this maximal specific activity of the transport complex is the selection objective, binding protein concentrations should exceed the concentration of both the scarce nutrient and the transporter. This increases the encounter rate of transporter with loaded binding protein at low substrate concentrations, thereby enhancing the affinity and specific uptake rate. These predictions are experimentally testable, and a number of observations confirm them. © 2015 FEBS.

  11. Regional distribution of serotonin transporter protein in postmortem human brain

    Energy Technology Data Exchange (ETDEWEB)

    Kish, Stephen J. [Human Neurochemical Pathology Laboratory, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada)]. E-mail: Stephen_Kish@CAMH.net; Furukawa, Yoshiaki [Human Neurochemical Pathology Laboratory, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada); Chang Lijan [Human Neurochemical Pathology Laboratory, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada); Tong Junchao [Human Neurochemical Pathology Laboratory, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada); Ginovart, Nathalie [PET Centre, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada); Wilson, Alan [PET Centre, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada); Houle, Sylvain [PET Centre, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada); Meyer, Jeffrey H. [PET Centre, Centre for Addiction and Mental Health, Toronto, ON, M5T 1R8 (Canada)

    2005-02-01

    Introduction: The primary approach in assessing the status of brain serotonin neurons in human conditions such as major depression and exposure to the illicit drug ecstasy has been the use of neuroimaging procedures involving radiotracers that bind to the serotonin transporter (SERT). However, there has been no consistency in the selection of a 'SERT-free' reference region for the estimation of free and nonspecific binding, as occipital cortex, cerebellum and white matter have all been employed. Objective and Methods: To identify areas of human brain that might have very low SERT levels, we measured, by a semiquantitative Western blotting procedure, SERT protein immunoreactivity throughout the postmortem brain of seven normal adult subjects. Results: Serotonin transporter could be quantitated in all examined brain areas. However, the SERT concentration in cerebellar cortex and white matter were only at trace values, being approximately 20% of average cerebral cortex and 5% of average striatum values. Conclusion: Although none of the examined brain areas are completely free of SERT, human cerebellar cortex has low SERT binding as compared to other examined brain regions, with the exception of white matter. Since the cerebellar cortical SERT binding is not zero, this region will not be a suitable reference region for SERT radioligands with very low free and nonspecific binding. For SERT radioligands with reasonably high free and nonspecific binding, the cerebellar cortex should be a useful reference region, provided other necessary radioligand assumptions are met.

  12. Regional distribution of serotonin transporter protein in postmortem human brain

    International Nuclear Information System (INIS)

    Kish, Stephen J.; Furukawa, Yoshiaki; Chang Lijan; Tong Junchao; Ginovart, Nathalie; Wilson, Alan; Houle, Sylvain; Meyer, Jeffrey H.

    2005-01-01

    Introduction: The primary approach in assessing the status of brain serotonin neurons in human conditions such as major depression and exposure to the illicit drug ecstasy has been the use of neuroimaging procedures involving radiotracers that bind to the serotonin transporter (SERT). However, there has been no consistency in the selection of a 'SERT-free' reference region for the estimation of free and nonspecific binding, as occipital cortex, cerebellum and white matter have all been employed. Objective and Methods: To identify areas of human brain that might have very low SERT levels, we measured, by a semiquantitative Western blotting procedure, SERT protein immunoreactivity throughout the postmortem brain of seven normal adult subjects. Results: Serotonin transporter could be quantitated in all examined brain areas. However, the SERT concentration in cerebellar cortex and white matter were only at trace values, being approximately 20% of average cerebral cortex and 5% of average striatum values. Conclusion: Although none of the examined brain areas are completely free of SERT, human cerebellar cortex has low SERT binding as compared to other examined brain regions, with the exception of white matter. Since the cerebellar cortical SERT binding is not zero, this region will not be a suitable reference region for SERT radioligands with very low free and nonspecific binding. For SERT radioligands with reasonably high free and nonspecific binding, the cerebellar cortex should be a useful reference region, provided other necessary radioligand assumptions are met

  13. The cholesterol space of the rat; L'espace cholesterol du rat

    Energy Technology Data Exchange (ETDEWEB)

    Chevallier, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The experiments consisted in feeding daily to rats the same mass of radioactive cholesterol, over variable time intervals. From the evolution of the specific radioactivity of cholesterol carbon-14 in the organs as a function of time, information relative to the transport of cholesterol in the organism may be obtained. 1) The cholesterol space, defined as the group of molecules capable of being transferred from the organs into the serum and vice versa, represents at the most 50 per cent of the total cholesterol of the adult rat. 2) The incessant interchange between the tissual and the serum cholesterol renews entirely or for the most part the cholesterol molecules contained in the following organs: spleen, heart, adipose tissue, suprarenal glands, lungs, bone marrow, liver, erythrocytes. For a second group of organs: skin, testicles, kidneys, colon, bones, muscles, only a fraction of their cholesterol is renewable by this process. No transfer can be detected at the level of the brain. 3) The relative speeds of the various means of appearance (absorption, synthesis) and disappearance (excretion, transformation) of the cholesterol from its space are such that a stationary isotopic state is established around the eighth day, when the animal absorbs 5 milligrams of radioactive cholesterol daily. (author) [French] Les experiences ont consiste a faire ingerer quotidiennement une meme masse de cholesterol radioactif a des rats, durant des laps de temps variables. L'evolution de la radioactivite specifique du carbone-14 du cholesterol des organes en fonction du temps permet d'obtenir des renseignements relatifs au transport du cholesterol dans l'organisme. 1) L'espace cholesterol defini comme l'ensemble des molecules susceptibles d'etre transferees des organes dans le serum, et vice-versa, represente au plus 50 pour cent du cholesterol total du rat adulte. 2) Le va et vient incessant entre le cholesterol tissulaire et le cholesterol serique renouvelle en totalite ou en

  14. Artificial membranes with selective nanochannels for protein transport

    KAUST Repository

    Sutisna, Burhannudin

    2016-09-05

    A poly(styrene-b-tert-butoxystyrene-b-styrene) copolymer was synthesized by anionic polymerization and hydrolyzed to poly(styrene-b-4-hydroxystyrene-b-styrene). Lamellar morphology was confirmed in the bulk after annealing. Membranes were fabricated by self-assembly of the hydrolyzed copolymer in solution, followed by water induced phase separation. A high density of pores of 4 to 5 nm diameter led to a water permeance of 40 L m−2 h−1 bar−1 and molecular weight cut-off around 8 kg mol−1. The morphology was controlled by tuning the polymer concentration, evaporation time, and the addition of imidazole and pyridine to stabilize the terpolymer micelles in the casting solution via hydrogen bond complexes. Transmission electron microscopy of the membrane cross-sections confirmed the formation of channels with hydroxyl groups beneficial for hydrogen-bond forming sites. The morphology evolution was investigated by time-resolved grazing incidence small angle X-ray scattering experiments. The membrane channels reject polyethylene glycol with a molecular size of 10 kg mol−1, but are permeable to proteins, such as lysozyme (14.3 kg mol−1) and cytochrome c (12.4 kg mol−1), due to the right balance of hydrogen bond interactions along the channels, electrostatic attraction, as well as the right pore sizes. Our results demonstrate that artificial channels can be designed for protein transport via block copolymer self-assembly using classical methods of membrane preparation.

  15. Artificial membranes with selective nanochannels for protein transport

    KAUST Repository

    Sutisna, Burhannudin; Polymeropoulos, Georgios; Mygiakis, E.; Musteata, Valentina-Elena; Peinemann, Klaus-Viktor; Smilgies, D. M.; Hadjichristidis, Nikolaos; Nunes, Suzana Pereira

    2016-01-01

    A poly(styrene-b-tert-butoxystyrene-b-styrene) copolymer was synthesized by anionic polymerization and hydrolyzed to poly(styrene-b-4-hydroxystyrene-b-styrene). Lamellar morphology was confirmed in the bulk after annealing. Membranes were fabricated by self-assembly of the hydrolyzed copolymer in solution, followed by water induced phase separation. A high density of pores of 4 to 5 nm diameter led to a water permeance of 40 L m−2 h−1 bar−1 and molecular weight cut-off around 8 kg mol−1. The morphology was controlled by tuning the polymer concentration, evaporation time, and the addition of imidazole and pyridine to stabilize the terpolymer micelles in the casting solution via hydrogen bond complexes. Transmission electron microscopy of the membrane cross-sections confirmed the formation of channels with hydroxyl groups beneficial for hydrogen-bond forming sites. The morphology evolution was investigated by time-resolved grazing incidence small angle X-ray scattering experiments. The membrane channels reject polyethylene glycol with a molecular size of 10 kg mol−1, but are permeable to proteins, such as lysozyme (14.3 kg mol−1) and cytochrome c (12.4 kg mol−1), due to the right balance of hydrogen bond interactions along the channels, electrostatic attraction, as well as the right pore sizes. Our results demonstrate that artificial channels can be designed for protein transport via block copolymer self-assembly using classical methods of membrane preparation.

  16. MLN64 induces mitochondrial dysfunction associated with increased mitochondrial cholesterol content

    Directory of Open Access Journals (Sweden)

    Elisa Balboa

    2017-08-01

    Full Text Available MLN64 is a late endosomal cholesterol-binding membrane protein that has been implicated in cholesterol transport from endosomal membranes to the plasma membrane and/or mitochondria, in toxin-induced resistance, and in mitochondrial dysfunction. Down-regulation of MLN64 in Niemann-Pick C1 deficient cells decreased mitochondrial cholesterol content, suggesting that MLN64 functions independently of NPC1. However, the role of MLN64 in the maintenance of endosomal cholesterol flow and intracellular cholesterol homeostasis remains unclear. We have previously described that hepatic MLN64 overexpression increases liver cholesterol content and induces liver damage. Here, we studied the function of MLN64 in normal and NPC1-deficient cells and we evaluated whether MLN64 overexpressing cells exhibit alterations in mitochondrial function. We used recombinant-adenovirus-mediated MLN64 gene transfer to overexpress MLN64 in mouse liver and hepatic cells; and RNA interference to down-regulate MLN64 in NPC1-deficient cells. In MLN64-overexpressing cells, we found increased mitochondrial cholesterol content and decreased glutathione (GSH levels and ATPase activity. Furthermore, we found decreased mitochondrial membrane potential and mitochondrial fragmentation and increased mitochondrial superoxide levels in MLN64-overexpressing cells and in NPC1-deficient cells. Consequently, MLN64 expression was increased in NPC1-deficient cells and reduction of its expression restore mitochondrial membrane potential and mitochondrial superoxide levels. Our findings suggest that MLN64 overexpression induces an increase in mitochondrial cholesterol content and consequently a decrease in mitochondrial GSH content leading to mitochondrial dysfunction. In addition, we demonstrate that MLN64 expression is increased in NPC cells and plays a key role in cholesterol transport into the mitochondria.

  17. A finite element model for protein transport in vivo

    Directory of Open Access Journals (Sweden)

    Montas Hubert J

    2007-06-01

    Full Text Available Abstract Background Biological mass transport processes determine the behavior and function of cells, regulate interactions between synthetic agents and recipient targets, and are key elements in the design and use of biosensors. Accurately predicting the outcomes of such processes is crucial to both enhancing our understanding of how these systems function, enabling the design of effective strategies to control their function, and verifying that engineered solutions perform according to plan. Methods A Galerkin-based finite element model was developed and implemented to solve a system of two coupled partial differential equations governing biomolecule transport and reaction in live cells. The simulator was coupled, in the framework of an inverse modeling strategy, with an optimization algorithm and an experimental time series, obtained by the Fluorescence Recovery after Photobleaching (FRAP technique, to estimate biomolecule mass transport and reaction rate parameters. In the inverse algorithm, an adaptive method was implemented to calculate sensitivity matrix. A multi-criteria termination rule was developed to stop the inverse code at the solution. The applicability of the model was illustrated by simulating the mobility and binding of GFP-tagged glucocorticoid receptor in the nucleoplasm of mouse adenocarcinoma. Results The numerical simulator shows excellent agreement with the analytic solutions and experimental FRAP data. Detailed residual analysis indicates that residuals have zero mean and constant variance and are normally distributed and uncorrelated. Therefore, the necessary and sufficient criteria for least square parameter optimization, which was used in this study, were met. Conclusion The developed strategy is an efficient approach to extract as much physiochemical information from the FRAP protocol as possible. Well-posedness analysis of the inverse problem, however, indicates that the FRAP protocol provides insufficient

  18. The cholesterol space of the rat

    International Nuclear Information System (INIS)

    Chevallier, F.

    1959-01-01

    The experiments consisted in feeding daily to rats the same mass of radioactive cholesterol, over variable time intervals. From the evolution of the specific radioactivity of cholesterol carbon-14 in the organs as a function of time, information relative to the transport of cholesterol in the organism may be obtained. 1) The cholesterol space, defined as the group of molecules capable of being transferred from the organs into the serum and vice versa, represents at the most 50 per cent of the total cholesterol of the adult rat. 2) The incessant interchange between the tissual and the serum cholesterol renews entirely or for the most part the cholesterol molecules contained in the following organs: spleen, heart, adipose tissue, suprarenal glands, lungs, bone marrow, liver, erythrocytes. For a second group of organs: skin, testicles, kidneys, colon, bones, muscles, only a fraction of their cholesterol is renewable by this process. No transfer can be detected at the level of the brain. 3) The relative speeds of the various means of appearance (absorption, synthesis) and disappearance (excretion, transformation) of the cholesterol from its space are such that a stationary isotopic state is established around the eighth day, when the animal absorbs 5 milligrams of radioactive cholesterol daily. (author) [fr

  19. Two endoplasmic reticulum (ER) membrane proteins that facilitate ER-to-Golgi transport of glycosylphosphatidylinositol-anchored proteins.

    Science.gov (United States)

    Barz, W P; Walter, P

    1999-04-01

    Many eukaryotic cell surface proteins are anchored in the lipid bilayer through glycosylphosphatidylinositol (GPI). GPI anchors are covalently attached in the endoplasmic reticulum (ER). The modified proteins are then transported through the secretory pathway to the cell surface. We have identified two genes in Saccharomyces cerevisiae, LAG1 and a novel gene termed DGT1 (for "delayed GPI-anchored protein transport"), encoding structurally related proteins with multiple membrane-spanning domains. Both proteins are localized to the ER, as demonstrated by immunofluorescence microscopy. Deletion of either gene caused no detectable phenotype, whereas lag1Delta dgt1Delta cells displayed growth defects and a significant delay in ER-to-Golgi transport of GPI-anchored proteins, suggesting that LAG1 and DGT1 encode functionally redundant or overlapping proteins. The rate of GPI anchor attachment was not affected, nor was the transport rate of several non-GPI-anchored proteins. Consistent with a role of Lag1p and Dgt1p in GPI-anchored protein transport, lag1Delta dgt1Delta cells deposit abnormal, multilayered cell walls. Both proteins have significant sequence similarity to TRAM, a mammalian membrane protein thought to be involved in protein translocation across the ER membrane. In vivo translocation studies, however, did not detect any defects in protein translocation in lag1Delta dgt1Delta cells, suggesting that neither yeast gene plays a role in this process. Instead, we propose that Lag1p and Dgt1p facilitate efficient ER-to-Golgi transport of GPI-anchored proteins.

  20. Low plasma lecithin : cholesterol acyltransferase and lipid transfer protein activities in growth hormone deficient and acromegalic men: role in altered high density lipoproteins

    NARCIS (Netherlands)

    Beentjes, JAM; van Tol, A; Sluiter, WJ; Dullaart, RPF

    2000-01-01

    Growth hormone (GH) deficiency and acromegaly may be associated with increased cardiovascular risk. Little is known about alterations in high density lipoproteins (HDL) in these conditions. Lecithin:cholesterol acyl transferase (LCAT) has the ability to esterify free cholesterol (FC) in HDL.

  1. Mechanism of transfer of LDL-derived free cholesterol to HDL subfractions in human plasma

    International Nuclear Information System (INIS)

    Miida, T.; Fielding, C.J.; Fielding, P.E.

    1990-01-01

    The transfer of [ 3 H]cholesterol in low-density lipoprotein (LDL) to different high-density lipoprotein (HDL) species in native human plasma was determined by using nondenaturing two-dimensional electrophoresis. Transfer from LDL had a t 1/2 at 37 degree C of 51 ± 8 min and an activation energy of 18.0 kCal mol -1 . There was unexpected specificity among HDL species as acceptors of LDL-derived labeled cholesterol. The largest fraction of the major α-migrating class (HDL 2b ) was the major initial acceptor of LDL-derived cholesterol. Kinetic analysis indicated a rapid secondary transfer from HDL 2b to smaller αHDL (particularly HDL 3 ) driven enzymatically by the lecithin-cholesterol acyltransferase reaction. Rates of transfer among αHDL were most rapid from the largest αHDL fraction (HDL 2b ), suggesting possible protein-mediated facilitation. Simultaneous measurements of the transport of LDL-derived and cell-derived isotopic cholesterol indicated that the former preferably utilized the αHDL pathyway, with little label in pre-βHDL. The same experiments confirmed earlier data that cell-derived cholesterol is preferentially channeled through pre-βHDL. The authors suggest that the functional heterogeneity of HDL demonstrated here includes the ability to independently process cell- and LDL-derived free cholesterol

  2. LDL-Cholesterol Increases the Transcytosis of Molecules through Endothelial Monolayers.

    Science.gov (United States)

    Magalhaes, Ana; Matias, Inês; Palmela, Inês; Brito, Maria Alexandra; Dias, Sérgio

    2016-01-01

    Cholesterol has been identified as a causative factor in numerous pathologies including atherosclerosis and cancer. One of the frequent effects of elevated cholesterol levels in humans is the compromise of endothelial function due to activation of pro-inflammatory signalling pathways. While the mechanisms involved in endothelial activation by cholesterol during an inflammatory response are well established, less is known about the mechanisms by which cholesterol may affect endothelial barrier function, which were the subject of the present study. Here we show that low density lipoprotein (LDL) increases the permeability of endothelial monolayers to high molecular weight dextrans in an LDL receptor and cholesterol-dependent manner. The increased permeability seen upon LDL treatment was not caused by disruption of cell-to-cell junctions as determined by a normal localization of VE-Cadherin and ZO-1 proteins, and no major alterations in transendothelial electrical resistance or permeability to fluorescein. We show instead that LDL increases the level of high molecular weight transcytosis and that this occurs in an LDL receptor, cholesterol and caveolae-dependent way. Our findings contribute to our understanding of the systemic pathological effects of elevated cholesterol and the transport of cargo through endothelial monolayers.

  3. Moderate alcohol consumption increases cholesterol efflux mediated by ABCA1

    NARCIS (Netherlands)

    Beulens, J.W.J.; Sierksma, A.; Tol, A. van; Fournier, N.; Gent, T. van; Paul, J.L.; Hendriks, H.F.J.

    2004-01-01

    Moderate alcohol consumption increases HDL cholesterol, which is involved in reverse cholesterol transport (RCT). The aim of this study was to investigate the effect of moderate alcohol consumption on cholesterol efflux, using J774 mouse macrophages and Fu5AH cells, and on other parameters in the

  4. [Correlation of retinol binding protein 4 with 
metabolic indexes of glucose and 
lipid, bile cholesterol saturation index].

    Science.gov (United States)

    Wang, Wen; Li, Nianfeng

    2015-06-01

    To measure retinol binding protein 4 (RBP4) levels in serum and bile and to analyze their relationship with insulin resistance, dyslipidemia or cholesterol saturation index (CSI).
 A total of 60 patients with gallstone were divided into a diabetes group (n=30) and a control group (n=30). The concentrations of RBP4 in serum and bile were detected by enzyme-linked immunosorbent assay (ELISA). Enzyme colorimetric method was used to measure the concentration of biliary cholesterol, bile acid and phospholipid. Biliary CSI was calculated by Carey table. Partial correlation and multiple linear regression analysis were used to evaluate the correlation between the RBP4 levels in serum or bile and the above indexes.
 The RBP4 concentrations in serum and bile in the diabetes group were significantly elevated compared with those in the control group (both Ptriglyceride (TG), serum high-density lipoprotein (HDL), bile TBA, bile total cholesterol (TC) , bile phospholipids and bile CSI between the 2 groups (all P>0.05); but the serum TC, low density lipoprotein (LDL), fasting blood glucose (FBG), fasting insulin (FINS), and homeostasis model assessment for insulin resistance (HOMA-IR) in the diabetes group were significantly increased compared to those in the control group (all Pindex (BMI), waist circumference (WC), FINS, FBG, TC, LDL and HOMA-IR (r=0.283, 0.405, 0.685, 0.667, 0.553, 0.424 and 0.735, respectively), and the serum RBP4 was also positively correlated with the WC, FINS, FBG, TC, LDL and HOMA-IR (r=0.317, 0.734, 0.609, 0.528, 0.386 and 0.751, respectively). Stepwise multivariate linear regression analysis suggested that the HOMA-IR, BMI and WC were independently correlated with the level of bile RBP4 (multiple regression equation: Ybile RBP4=2.372XHOMA-IR+0.420XBMI+0.178XWC-26.813), and the serum RBP4 level was correlated with the HOMA-IR and WC independently (multiple regression equation: Yserum RBP4=2.832XHOMA-IR +0.235XWC-20.128). Multiple regression equations

  5. Evidence of a gustatory-vestibular pathway for protein transport.

    Science.gov (United States)

    Gacek, Richard; Lyon, Michael J

    2010-02-01

    To demonstrate anatomically a pathway for protein transport from the palate to the vestibular system. The vestibulofacial anastomosis and associated ganglion cells were identified in a collection of 160 horizontally sectioned human temporal bones that had been stained with hematoxylin and eosin. Wheat germ agglutinin-horseradish peroxidase (HRP) was applied to the greater superficial petrosal nerve in 4 Sprague-Dawley rats. After 30 hours, the rats were killed by intracardiac perfusion, and the seventh and eighth nerves with adjacent brainstem removed. Frozen sections cut at 30 mum through this block were then reacted for HRP, counterstained with neutral red, and mounted on slides for examination in the light microscope. Thirty-two of the 160 human temporal bones contained sections through the vestibulofacial anastomosis and its ganglion. In all cases, the ganglion was incorporated into the vestibular ganglion (VG) adjacent to the nervus intermedius. In all 4 experimental rats, HRP reaction product labeled a small number of ganglion cells in the VG adjacent to the nervus intermedius and facial nerve. These observations support the presence of a pathway from receptors in the palate to the VG.

  6. Training-induced changes in membrane transport proteins of human skeletal muscle

    DEFF Research Database (Denmark)

    Juel, C.

    2006-01-01

    Training improves human physical performance by inducing structural and cardiovascular changes, metabolic changes, and changes in the density of membrane transport proteins. This review focuses on the training-induced changes in proteins involved in sarcolemmal membrane transport. It is concluded...

  7. Prediction of membrane transport proteins and their substrate specificities using primary sequence information.

    Directory of Open Access Journals (Sweden)

    Nitish K Mishra

    Full Text Available Membrane transport proteins (transporters move hydrophilic substrates across hydrophobic membranes and play vital roles in most cellular functions. Transporters represent a diverse group of proteins that differ in topology, energy coupling mechanism, and substrate specificity as well as sequence similarity. Among the functional annotations of transporters, information about their transporting substrates is especially important. The experimental identification and characterization of transporters is currently costly and time-consuming. The development of robust bioinformatics-based methods for the prediction of membrane transport proteins and their substrate specificities is therefore an important and urgent task.Support vector machine (SVM-based computational models, which comprehensively utilize integrative protein sequence features such as amino acid composition, dipeptide composition, physico-chemical composition, biochemical composition, and position-specific scoring matrices (PSSM, were developed to predict the substrate specificity of seven transporter classes: amino acid, anion, cation, electron, protein/mRNA, sugar, and other transporters. An additional model to differentiate transporters from non-transporters was also developed. Among the developed models, the biochemical composition and PSSM hybrid model outperformed other models and achieved an overall average prediction accuracy of 76.69% with a Mathews correlation coefficient (MCC of 0.49 and a receiver operating characteristic area under the curve (AUC of 0.833 on our main dataset. This model also achieved an overall average prediction accuracy of 78.88% and MCC of 0.41 on an independent dataset.Our analyses suggest that evolutionary information (i.e., the PSSM and the AAIndex are key features for the substrate specificity prediction of transport proteins. In comparison, similarity-based methods such as BLAST, PSI-BLAST, and hidden Markov models do not provide accurate predictions

  8. Intestinal SR-BI does not impact cholesterol absorption or transintestinal cholesterol efflux in mice

    NARCIS (Netherlands)

    Bura, Kanwardeep S.; Lord, Caleb; Marshall, Stephanie; McDaniel, Allison; Thomas, Gwyn; Warrier, Manya; Zhang, Jun; Davis, Matthew A.; Sawyer, Janet K.; Shah, Ramesh; Wilson, Martha D.; Dikkers, Arne; Tietge, Uwe J. F.; Collet, Xavier; Rudel, Lawrence L.; Temel, Ryan E.; Brown, J. Mark

    Reverse cholesterol transport (RCT) can proceed through the classic hepatobiliary route or through the non-biliary transintestinal cholesterol efflux (TICE) pathway. Scavenger receptor class B type I (SR-BI) plays a critical role in the classic hepatobiliary route of RCT. However, the role of SR-BI

  9. Analysis of Nanobody-Epitope Interactions in Living Cells via Quantitative Protein Transport Assays.

    Science.gov (United States)

    Früholz, Simone; Pimpl, Peter

    2017-01-01

    Over the past few decades, quantitative protein transport analyses have been used to elucidate the sorting and transport of proteins in the endomembrane system of plants. Here, we have applied our knowledge about transport routes and the corresponding sorting signals to establish an in vivo system for testing specific interactions between soluble proteins.Here, we describe the use of quantitative protein transport assays in tobacco mesophyll protoplasts to test for interactions occurring between a GFP-binding nanobody and its GFP epitope. For this, we use a secreted GFP-tagged α-amylase as a reporter together with a vacuolar-targeted RFP-tagged nanobody. The interaction between these proteins is then revealed by a transport alteration of the secretory reporter due to the interaction-triggered attachment of the vacuolar sorting signal.

  10. Inclusion of Almonds in a Cholesterol-Lowering Diet Improves Plasma HDL Subspecies and Cholesterol Efflux to Serum in Normal-Weight Individuals with Elevated LDL Cholesterol.

    Science.gov (United States)

    Berryman, Claire E; Fleming, Jennifer A; Kris-Etherton, Penny M

    2017-08-01

    Background : Almonds may increase circulating HDL cholesterol when substituted for a high-carbohydrate snack in an isocaloric diet, yet little is known about the effects on HDL biology and function. Objective: The objective was to determine whether incorporating 43 g almonds/d in a cholesterol-lowering diet would improve HDL subspecies and function, which were secondary study outcomes. Methods: In a randomized, 2-period, crossover, controlled-feeding study, a diet with 43 g almonds/d (percentage of total energy: 51% carbohydrate, 16% protein, and 32% total and 8% saturated fat) was compared with a similar diet with an isocaloric muffin substitution (58% carbohydrate, 15% protein, and 26% total and 8% saturated fat) in men and women with elevated LDL cholesterol. Plasma HDL subspecies and cholesterol efflux from J774 macrophages to human serum were measured at baseline and after each diet period. Diet effects were examined in all participants ( n = 48) and in normal-weight (body mass index: almond diet, compared with the control diet, increased α-1 HDL [mean ± SEM: 26.7 ± 1.5 compared with 24.3 ± 1.3 mg apolipoprotein A-I (apoA-I)/dL; P = 0.001]. In normal-weight participants, the almond diet, relative to the control diet, increased α-1 HDL (33.7 ± 3.2 compared with 28.4 ± 2.6 mg apoA-I/dL), the α-1 to pre-β-1 ratio [geometric mean (95% CI): 4.3 (3.3, 5.7) compared with 3.1 (2.4, 4.0)], and non-ATP-binding cassette transporter A1 cholesterol efflux (8.3% ± 0.4% compared with 7.8% ± 0.3%) and decreased pre-β-2 (3.8 ± 0.4 compared with 4.6 ± 0.4 mg apoA-I/dL) and α-3 (23.5 ± 0.9 compared with 26.9 ± 1.1 mg apoA-I/dL) HDL ( P almonds for a carbohydrate-rich snack within a lower-saturated-fat diet may be a simple strategy to maintain a favorable circulating HDL subpopulation distribution and improve cholesterol efflux in normal-weight individuals with elevated LDL cholesterol. This trial was registered at clinicaltrials.gov as NCT01101230. © 2017

  11. Controlling Cholesterol with Statins

    Science.gov (United States)

    ... For Consumers Home For Consumers Consumer Updates Controlling Cholesterol with Statins Share Tweet Linkedin Pin it More ... not, the following tips can help keep your cholesterol in check: Talk with your healthcare provider about ...

  12. Cholesterol - drug treatment

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000314.htm Cholesterol - drug treatment To use the sharing features on ... treatment; Hardening of the arteries - statin Statins for Cholesterol Statins reduce your risk of heart disease, stroke, ...

  13. The substrate-binding protein imposes directionality on an electrochemical sodium gradient-driven TRAP transporter

    NARCIS (Netherlands)

    Mulligan, Christopher; Geertsma, Eric R.; Severi, Emmanuele; Kelly, David J.; Poolman, Bert; Thomas, Gavin H.

    2009-01-01

    Substrate-binding protein-dependent secondary transporters are widespread in prokaryotes and are represented most frequently by members of the tripartite ATP-independent periplasmic (TRAP) transporter family. Here, we report the membrane reconstitution of a TRAP transporter, the sialic acid-specific

  14. Structural Basis for a Ribofuranosyl Binding Protein: Insights into the Furanose Specific Transport

    Energy Technology Data Exchange (ETDEWEB)

    Bagaria, A.; Swaminathan, S.; Kumaran, D.; Burley, S. K.

    2011-04-01

    The ATP-binding cassette transporters (ABC-transporters) are members of one of the largest protein superfamilies, with representatives in all extant phyla. These integral membrane proteins utilize the energy of ATP hydrolysis to carry out certain biological processes, including translocation of various substrates across membranes and non-transport related processes such as translation of RNA and DNA repair. Typically, such transport systems in bacteria consist of an ATP binding component, a transmembrane permease, and a periplasmic receptor or binding protein. Soluble proteins found in the periplasm of gram-negative bacteria serve as the primary receptors for transport of many compounds, such as sugars, small peptides, and some ions. Ligand binding activates these periplasmic components, permitting recognition by the membrane spanning domain, which supports for transport and, in some cases, chemotaxis. Transport and chemotaxis processes appear to be independent of one another, and a few mutants of bifunctional periplasmic components reveal the absence of one or the other function. Previously published high-resolution X-ray structures of various periplasmic ligand binding proteins include Arabinose binding protein (ABP), Allose binding protein (ALBP), Glucose-galactose binding protein (GBP) and Ribose binding protein (RBP). Each of these proteins consists of two structurally similar domains connected by a three-stranded hinge region, with ligand buried between the domains. Upon ligand binding and release, various conformational changes have been observed. For RBP, open (apo) and closed (ligand bound) conformations have been reported and so for MBP. The closed/active form of the protein interacts with the integral membrane component of the system in both transport and chemotaxis. Herein, we report 1.9{angstrom} resolution X-ray structure of the R{sub f}BP periplasmic component of an ABC-type sugar transport system from Hahella chejuensis (UniProt Id Q2S7D2) bound to

  15. High-density lipoprotein cholesterol: How High

    Directory of Open Access Journals (Sweden)

    G Rajagopal

    2012-01-01

    Full Text Available The high-density lipoprotein cholesterol (HDL-C is considered anti-atherogenic good cholesterol. It is involved in reverse transport of lipids. Epidemiological studies have found inverse relationship of HDL-C and coronary heart disease (CHD risk. When grouped according to HDL-C, subjects having HDL-C more than 60 mg/dL had lesser risk of CHD than those having HDL-C of 40-60 mg/dL, who in turn had lesser risk than those who had HDL-C less than 40 mg/dL. No upper limit for beneficial effect of HDL-C on CHD risk has been identified. The goals of treating patients with low HDL-C have not been firmly established. Though many drugs are known to improve HDL-C concentration, statins are proven to improve CHD risk and mortality. Cholesteryl ester transfer protein (CETP is involved in metabolism of HDL-C and its inhibitors are actively being screened for clinical utility. However, final answer is still awaited on CETP-inhibitors.

  16. Mitochondrial damage and cholesterol storage in human hepatocellular carcinoma cells with silencing of UBIAD1 gene expression

    Directory of Open Access Journals (Sweden)

    Carlos R. Morales

    2014-01-01

    Full Text Available Heterozygous mutations in the UBIAD1 gene cause Schnyder corneal dystrophy characterized by abnormal cholesterol and phospholipid deposits in the cornea. Ubiad1 protein was recently identified as Golgi prenyltransferase responsible for biosynthesis of vitamin K2 and CoQ10, a key protein in the mitochondrial electron transport chain. Our study shows that silencing UBIAD1 in cultured human hepatocellular carcinoma cells causes dramatic morphological changes and cholesterol storage in the mitochondria, emphasizing an important role of UBIAD1 in mitochondrial function.

  17. Home-Use Tests - Cholesterol

    Science.gov (United States)

    ... Medical Procedures In Vitro Diagnostics Home Use Tests Cholesterol Share Tweet Linkedin Pin it More sharing options ... a home-use test kit to measure total cholesterol. What cholesterol is: Cholesterol is a fat (lipid) ...

  18. Cholesterol asymmetry in synaptic plasma membranes.

    Science.gov (United States)

    Wood, W Gibson; Igbavboa, Urule; Müller, Walter E; Eckert, Gunter P

    2011-03-01

    Lipids are essential for the structural and functional integrity of membranes. Membrane lipids are not randomly distributed but are localized in different domains. A common characteristic of these membrane domains is their association with cholesterol. Lipid rafts and caveolae are examples of cholesterol enriched domains, which have attracted keen interest. However, two other important cholesterol domains are the exofacial and cytofacial leaflets of the plasma membrane. The two leaflets that make up the bilayer differ in their fluidity, electrical charge, lipid distribution, and active sites of certain proteins. The synaptic plasma membrane (SPM) cytofacial leaflet contains over 85% of the total SPM cholesterol as compared with the exofacial leaflet. This asymmetric distribution of cholesterol is not fixed or immobile but can be modified by different conditions in vivo: (i) chronic ethanol consumption; (ii) statins; (iii) aging; and (iv) apoE isoform. Several potential candidates have been proposed as mechanisms involved in regulation of SPM cholesterol asymmetry: apoE, low-density lipoprotein receptor, sterol carrier protein-2, fatty acid binding proteins, polyunsaturated fatty acids, P-glycoprotein and caveolin-1. This review examines cholesterol asymmetry in SPM, potential mechanisms of regulation and impact on membrane structure and function. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  19. Fast axonal transport of labeled proteins in motoneurons of exercise-trained rats

    International Nuclear Information System (INIS)

    Jasmin, B.J.; Lavoie, P.A.; Gardiner, P.F.

    1988-01-01

    In this study, the fast orthograde axonal transport of radiolabeled proteins was measured to determine the effects of endurance-running training on transport velocity and amounts of transported proteins in rat sciatic motoneurons. Female rats were subjected to a progressive running-training program for 10-12 wk. Twenty-four hours after the last training session, rats underwent right L4-L5 dorsal root ganglionectomy. The next day, 20 microCi of [3H]leucine was injected bilaterally in the vicinity of the motoneuronal cell bodies supplying the sciatic nerve, to study axonal transport parameters. Results showed that peak and average transport velocities of labeled proteins were significantly (P less than 0.05) increased by 22 and 29%, respectively, in the deafferented nerves of the runners as compared with controls. Moreover, the amount of total transported protein-bound radioactivity was increased in both left (40%) and right (37%) sciatic nerves of the runners. An exhaustive exercise session reduced (P less than 0.05) peak displacement (8%) and total transported protein-bound radioactivity (36%) in the sciatic nerves of control rats, whereas no changes were noticed in trained animals. The data suggest that chronic endurance running induces significant adaptations in the fast axonal transport of labeled proteins

  20. Sex Differences in the Hepatic Cholesterol Sensing Mechanisms in Mice

    Directory of Open Access Journals (Sweden)

    Ingemar Björkhem

    2013-09-01

    Full Text Available Cholesterol is linked to many multifactorial disorders, including different forms of liver disease where development and severity depend on the sex. We performed a detailed analysis of cholesterol and bile acid synthesis pathways at the level of genes and metabolites combined with the expression studies of hepatic cholesterol uptake and transport in female and male mice fed with a high-fat diet with or without cholesterol. Lack of dietary cholesterol led to a stronger response of the sterol sensing mechanism in females, resulting in higher expression of cholesterogenic genes compared to males. With cholesterol in the diet, the genes were down-regulated in both sexes; however, males maintained a more efficient hepatic metabolic flux through the pathway. Females had higher content of hepatic cholesterol but this was likely not due to diminished excretion but rather due to increased synthesis and absorption. Dietary cholesterol and sex were not important for gallbladder bile acids composition. Neither sex up-regulated Cyp7a1 upon cholesterol loading and there was no compensatory up-regulation of Abcg5 or Abcg8 transporters. On the other hand, females had higher expression of the Ldlr and Cd36 genes. These findings explain sexual dimorphism of cholesterol metabolism in response to dietary cholesterol in a high-fat diet in mice, which contributes to understanding the sex-basis of cholesterol-associated liver diseases.

  1. Polymorphism 1936A > G in the AKAP10 gene (encoding A-kinase-anchoring protein 10) is associated with higher cholesterol cord blood concentration in Polish full-term newsborns.

    Science.gov (United States)

    Łoniewska, Beata; Kaczmarczyk, Mariusz; Clark, Jeremy Simon; Kordek, Agnieszka; Ciechanowicz, Andrzej

    2013-03-01

    A-Kinase anchoring proteins (AKAPs) coordinate the specificity of protein kinase A signaling by localizing the kinase to subcellular sites. The 1936G (V646) AKAP10 allele has been associated with adults with low cholinergic/vagus nerve sensitivity and with newborns with increased blood pressure. Decreased activity of the parasympathetic system is associated with risk of metabolic syndrome. The aim of this study was to answer the question of whether 1936A > G AKAP10 polymorphism is associated with metabolic changes in full-term newborns that are predictive factors for the metabolic phenotype in adulthood. The study included 114 consecutive healthy Polish newborns born after the end of the 37 th week of gestation to healthy women with uncomplicated pregnancies. At birth, cord blood of neonates was obtained for isolation of genomic DNA and cholesterol as well as triglyceride concentration. The cholesterol level in homozygotes GG was significantly higher than that in 1936A variant carriers (AG + AA, recessive mode of inheritance). Our results demonstrate a possible association between the 1936G AKAP10 variant and the total cholesterol level in the cord blood of the Polish newborn population.

  2. Effects of isoflavone-containing soya protein on ex vivo cholesterol efflux, vascular function and blood markers of CVD risk in adults with moderately elevated blood pressure: a dose-response randomised controlled trial.

    Science.gov (United States)

    Richter, Chesney K; Skulas-Ray, Ann C; Fleming, Jennifer A; Link, Christina J; Mukherjea, Ratna; Krul, Elaine S; Kris-Etherton, Penny M

    2017-05-01

    Emerging CVD risk factors (e.g. HDL function and central haemodynamics) may account for residual CVD risk experienced by individuals who meet LDL-cholesterol and blood pressure (BP) targets. Recent evidence suggests that these emerging risk factors can be modified by polyphenol-rich interventions such as soya, but additional research is needed. This study was designed to investigate the effects of an isoflavone-containing soya protein isolate (delivering 25 and 50 g/d soya protein) on HDL function (i.e. ex vivo cholesterol efflux), macrovascular function and blood markers of CVD risk. Middle-aged adults (n 20; mean age=51·6 (sem 6·6) years) with moderately elevated brachial BP (mean systolic BP=129 (sem 9) mmHg; mean diastolic BP=82·5 (sem 8·4) mmHg) consumed 0 (control), 25 and 50 g/d soya protein in a randomised cross-over design. Soya and control powders were consumed for 6 weeks each with a 2-week compliance break between treatment periods. Blood samples and vascular function measures were obtained at baseline and following each supplementation period. Supplementation with 50 g/d soya protein significantly reduced brachial diastolic BP (-2·3 mmHg) compared with 25 g/d soya protein (Tukey-adjusted P=0·03) but not the control. Soya supplementation did not improve ex vivo cholesterol efflux, macrovascular function or other blood markers of CVD risk compared with the carbohydrate-matched control. Additional research is needed to clarify whether effects on these CVD risk factors depend on the relative health of participants and/or equol producing capacity.

  3. Dietary saturated fat/cholesterol, but not unsaturated fat or starch, induces C-reactive protein associated early atherosclerosis and ectopic fat deposition in diabetic pigs

    Directory of Open Access Journals (Sweden)

    Serlie Mireille J

    2011-07-01

    Full Text Available Abstract Background Diabetes is thought to accelerate cardiovascular disease depending on the type of diet. This study in diabetic subjects was performed to investigate the metabolic, inflammatory and cardiovascular effects of nutritional components typically present in a Western, Mediterranean or high glycaemic diet. Methods Streptozotocin-diabetic pigs (~45 kg were fed for 10 weeks supplemental (40% of dietary energy saturated fat/cholesterol (SFC, unsaturated fat (UF or starch (S in an eucaloric dietary intervention study. Results Fasting plasma total, LDL and HDL cholesterol concentrations were 3-5 fold higher (p 2 = 0.95. Retroperitoneal fat depot weight (g was intermediate in SFC (260 ± 72, lowest in S (135 ± 51 and highest (p Conclusion Dietary saturated fat/cholesterol induces inflammation, atherosclerosis and ectopic fat deposition whereas an equally high dietary unsaturated fat load does not induce these abnormalities and shows beneficial effects on postprandial glycaemia in diabetic pigs.

  4. Active zone proteins are transported via distinct mechanisms regulated by Par-1 kinase.

    Directory of Open Access Journals (Sweden)

    Kara R Barber

    2017-02-01

    Full Text Available Disruption of synapses underlies a plethora of neurodevelopmental and neurodegenerative disease. Presynaptic specialization called the active zone plays a critical role in the communication with postsynaptic neuron. While the role of many proteins at the active zones in synaptic communication is relatively well studied, very little is known about how these proteins are transported to the synapses. For example, are there distinct mechanisms for the transport of active zone components or are they all transported in the same transport vesicle? Is active zone protein transport regulated? In this report we show that overexpression of Par-1/MARK kinase, a protein whose misregulation has been implicated in Autism spectrum disorders (ASDs and neurodegenerative disorders, lead to a specific block in the transport of an active zone protein component- Bruchpilot at Drosophila neuromuscular junctions. Consistent with a block in axonal transport, we find a decrease in number of active zones and reduced neurotransmission in flies overexpressing Par-1 kinase. Interestingly, we find that Par-1 acts independently of Tau-one of the most well studied substrates of Par-1, revealing a presynaptic function for Par-1 that is independent of Tau. Thus, our study strongly suggests that there are distinct mechanisms that transport components of active zones and that they are tightly regulated.

  5. Transport of soluble proteins through the Golgi occurs by diffusion via continuities across cisternae

    Science.gov (United States)

    Beznoussenko, Galina V; Parashuraman, Seetharaman; Rizzo, Riccardo; Polishchuk, Roman; Martella, Oliviano; Di Giandomenico, Daniele; Fusella, Aurora; Spaar, Alexander; Sallese, Michele; Capestrano, Maria Grazia; Pavelka, Margit; Vos, Matthijn R; Rikers, Yuri GM; Helms, Volkhard; Mironov, Alexandre A; Luini, Alberto

    2014-01-01

    The mechanism of transport through the Golgi complex is not completely understood, insofar as no single transport mechanism appears to account for all of the observations. Here, we compare the transport of soluble secretory proteins (albumin and α1-antitrypsin) with that of supramolecular cargoes (e.g., procollagen) that are proposed to traverse the Golgi by compartment progression–maturation. We show that these soluble proteins traverse the Golgi much faster than procollagen while moving through the same stack. Moreover, we present kinetic and morphological observations that indicate that albumin transport occurs by diffusion via intercisternal continuities. These data provide evidence for a transport mechanism that applies to a major class of secretory proteins and indicate the co-existence of multiple intra-Golgi trafficking modes. DOI: http://dx.doi.org/10.7554/eLife.02009.001 PMID:24867214

  6. Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins.

    NARCIS (Netherlands)

    Hsu, Y.J.; Dimke, H.; Schoeber, J.P.H.; Hsu, S.C.; Lin, S.H.; Chu, P.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2010-01-01

    Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had

  7. Nuclear transport factor directs localization of protein synthesis during mitosis

    NARCIS (Netherlands)

    Bogaart, Geert van den; Meinema, Anne C.; Krasnikov, Viktor; Veenhoff, Liesbeth M.; Poolman, Bert

    Export of messenger RNA from the transcription site in the nucleus and mRNA targeting to the translation site in the cytoplasm are key regulatory processes in protein synthesis. In yeast, the mRNA-binding proteins Nab2p and Nab4p/Hrp1p accompany transcripts to their translation site, where the

  8. Communication Maps: Exploring Energy Transport through Proteins and Water

    Czech Academy of Sciences Publication Activity Database

    Agbo, J. K.; Gnanasekaran, Ramachandran; Leitner, D. M.

    2014-01-01

    Roč. 54, 8/9 (2014), s. 1065-1073 ISSN 0021-2148 Institutional support: RVO:61388963 Keywords : energy transfer * heme proteins * hydrogen bonds * molecular modeling * protein models Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.221, year: 2014

  9. Effects of apolipoproteins on the kinetics of cholesterol exchange

    International Nuclear Information System (INIS)

    Letizia, J.Y.; Phillips, M.C.

    1991-01-01

    The effects of apolipoproteins on the kinetics of cholesterol exchange have been investigated by monitoring the transfer of [ 14 C]cholesterol from donor phospholipid/cholesterol complexes containing human apolipoproteins A, B, or C. Negatively charged discoidal and vesicular particles containing purified apolipoproteins complexed with lipid and a trace of [ 14 C]cholesterol were incubated with a 10-fold excess of neutral, acceptor, small unilamellar vesicles. The donor and acceptor particles were separated by chromatogrphy of DEAE-Sepharose, and the rate of movement of labeled cholesterol was analyzed as a first-order exchange process. The kinetics of exchange of cholesterol from both vesicular and discoidal complexes that contain apoproteins are consistent with an aqueous diffusion mechanism, as has been established previously for PC/cholesterol SUV. Apolipoproteins A-I, A-II, reduced and carboxymethylated A-11, and B-100 present in SUV at the same lipid/protein (w/w) ratio all enhance the rate of cholesterol exchange to about the same degree. Cholesterol molecules exchange more rapidly from discoidal complexes. Generally, as the diameter of apoprotein/phospholipid/cholesterol discs decreases, t 1/2 for cholesterol exchange decreases. Since small bilayer discs have a relatively high ratio of boundary to face surface area, cholesterol molecules desorb more rapidly than from larger discs. The modulation of lipid packing by the apoprotein molecules present at the surface of lipoprotein particles affects the rate of cholesterol exchange from such particles

  10. Novel Apo E-Derived ABCA1 Agonist Peptide (CS-6253 Promotes Reverse Cholesterol Transport and Induces Formation of preβ-1 HDL In Vitro.

    Directory of Open Access Journals (Sweden)

    Anouar Hafiane

    Full Text Available Apolipoprotein (apo mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253 that was non-toxic. We evaluated this peptide designed from the carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These

  11. Transport proteins of parasitic protists and their role in nutrient salvage.

    Science.gov (United States)

    Dean, Paul; Major, Peter; Nakjang, Sirintra; Hirt, Robert P; Embley, T Martin

    2014-01-01

    The loss of key biosynthetic pathways is a common feature of important parasitic protists, making them heavily dependent on scavenging nutrients from their hosts. This is often mediated by specialized transporter proteins that ensure the nutritional requirements of the parasite are met. Over the past decade, the completion of several parasite genome projects has facilitated the identification of parasite transporter proteins. This has been complemented by functional characterization of individual transporters along with investigations into their importance for parasite survival. In this review, we summarize the current knowledge on transporters from parasitic protists and highlight commonalities and differences in the transporter repertoires of different parasitic species, with particular focus on characterized transporters that act at the host-pathogen interface.

  12. Localization and role of NPC1L1 in cholesterol absorption in human intestine.

    Science.gov (United States)

    Sané, Alain Théophile; Sinnett, Daniel; Delvin, Edgard; Bendayan, Moise; Marcil, Valérie; Ménard, Daniel; Beaulieu, Jean-François; Levy, Emile

    2006-10-01

    Recent studies have documented the presence of Niemann-Pick C1-Like 1 (NPC1L1) in the small intestine and its capacity to transport cholesterol in mice and rats. The current investigation was undertaken to explore the localization and function of NPC1L1 in human enterocytes. Cell fractionation experiments revealed an NPC1L1 association with apical membrane of the enterocyte in human jejunum. Signal was also detected in lysosomes, endosomes, and mitochondria. Confirmation of cellular NPC1L1 distribution was obtained by immunocytochemistry. Knockdown of NPC1L1 caused a decline in the ability of Caco-2 cells to capture micellar [(14)C]free cholesterol. Furthermore, this NPC1L1 suppression resulted in increased and decreased mRNA levels and activity of HMG-CoA reductase, the rate-limiting step in cholesterol synthesis, and of ACAT, the key enzyme in cholesterol esterification, respectively. An increase was also noted in the transcriptional factor sterol-regulatory element binding protein that modulates cholesterol homeostasis. Efforts were devoted to define the impact of NPC1L1 knockdown on other mediators of cholesterol uptake. RT-PCR evidence is presented to show the significant decrease in the levels of scavenger receptor class B type I (SR-BI) with no changes in ABCA1, ABCG5, and cluster determinant 36 in NPC1L1-deficient Caco-2 cells. Together, our data suggest that NPC1L1 contributes to intestinal cholesterol homeostasis and possibly cooperates with SR-BI to mediate cholesterol absorption in humans.

  13. Effect of physical training on glucose transporter protein and mRNA levels in rat adipocytes

    DEFF Research Database (Denmark)

    Stallknecht, B; Andersen, P H; Vinten, J

    1993-01-01

    Physical training increases insulin-stimulated glucose transport and the number of glucose transporters in adipocytes measured by cytochalasin B binding. In the present study we used immunoblotting to measure the abundance of two glucose transporters (GLUT-4, GLUT-1) in white adipocytes from....../or intrinsic activity). GLUT-1 protein and mRNA levels/adipocyte volume did not change with age or training....

  14. Hepatic nuclear sterol regulatory binding element protein 2 abundance is decreased and that of ABCG5 increased in male hamsters fed plant sterols.

    Science.gov (United States)

    Harding, Scott V; Rideout, Todd C; Jones, Peter J H

    2010-07-01

    The effect of dietary plant sterols on cholesterol homeostasis has been well characterized in the intestine, but how plant sterols affect lipid metabolism in other lipid-rich tissues is not known. Changes in hepatic cholesterol homeostasis in response to high dietary intakes of plant sterols were determined in male golden Syrian hamsters fed hypercholesterolemia-inducing diets with and without 2% plant sterols (wt:wt; Reducol, Forbes Meditech) for 28 d. Plasma and hepatic cholesterol concentrations, cholesterol biosynthesis and absorption, and changes in the expression of sterol response element binding protein 2 (SREBP2) and liver X receptor-beta (LXRbeta) and their target genes were measured. Plant sterol feeding reduced plasma total cholesterol, non-HDL cholesterol, and HDL cholesterol concentrations 43% (P 6-fold (P = 0.029) and >2-fold (P sterol-fed hamsters compared with controls. Plant sterol feeding also increased fractional cholesterol synthesis >2-fold (P sterol feeding increased hepatic protein expression of cytosolic (inactive) SREBP2, decreased nuclear (active) SREBP2, and tended to increase LXRbeta (P = 0.06) and ATP binding cassette transporter G5, indicating a differential modulation of the expression of proteins central to cholesterol metabolism. In conclusion, high-dose plant sterol feeding of hamsters changes hepatic protein abundance in favor of cholesterol excretion despite lower hepatic cholesterol concentrations and higher cholesterol fractional synthesis.

  15. Cholesterol: a novel regulatory role in myelin formation.

    Science.gov (United States)

    Saher, Gesine; Quintes, Susanne; Nave, Klaus-Armin

    2011-02-01

    Myelin consists of tightly compacted membranes that form an insulating sheath around axons. The function of myelin for rapid saltatory nerve conduction is dependent on its unique composition, highly enriched in glycosphingolipids and cholesterol. Cholesterol emerged as the only integral myelin component that is essential and rate limiting for the development of CNS and PNS myelin. Experiments with conditional mouse mutants that lack cholesterol biosynthesis in oligodendrocytes revealed that only minimal changes of the CNS myelin lipid composition are tolerated. In Schwann cells of the PNS, protein trafficking and myelin compaction depend on cholesterol. In this review, the authors summarize the role of cholesterol in myelin biogenesis and myelin disease.

  16. Effect of electric charge on the transperitoneal transport of plasma proteins during CAPD

    NARCIS (Netherlands)

    Buis, B.; Koomen, G. C.; Imholz, A. L.; Struijk, D. G.; Reddingius, R. E.; Arisz, L.; Krediet, R. T.

    1996-01-01

    BACKGROUND: Controversy exists as to whether electric charges of plasma proteins influence their transport across the peritoneal membrane during CAPD. Fixed negative charges in the peritoneal membrane are diminished during peritonitis in rats. METHODS: Peritoneal clearances of 10 proteins and their

  17. National Cholesterol Education Month

    Centers for Disease Control (CDC) Podcasts

    2009-09-01

    Do you know your cholesterol numbers? Your doctor can do a simple test to check your cholesterol levels and help you make choices that lower your risk for heart disease and stroke.  Created: 9/1/2009 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 9/9/2009.

  18. Retrograde transport of protein toxins through the Golgi apparatus

    DEFF Research Database (Denmark)

    Sandvig, Kirsten; Skotland, Tore; van Deurs, Bo

    2013-01-01

    at the cell surface, and they are endocytosed both by clathrin-dependent and clathrin-independent mechanisms. Sorting to the Golgi and retrograde transport to the endoplasmic reticulum (ER) are common to these toxins, but the exact mechanisms turn out to be toxin and cell-type dependent. In the ER...

  19. [Trans-intestinal cholesterol excretion (TICE): a new route for cholesterol excretion].

    Science.gov (United States)

    Blanchard, Claire; Moreau, François; Cariou, Bertrand; Le May, Cédric

    2014-10-01

    The small intestine plays a crucial role in dietary and biliary cholesterol absorption, as well as its lymphatic secretion as chylomicrons (lipoprotein exogenous way). Recently, a new metabolic pathway called TICE (trans-intestinal excretion of cholesterol) that plays a central role in cholesterol metabolism has emerged. TICE is an inducible way, complementary to the hepatobiliary pathway, allowing the elimination of the plasma cholesterol directly into the intestine lumen through the enterocytes. This pathway is poorly characterized but several molecular actors of TICE have been recently identified. Although it is a matter of debate, two independent studies suggest that TICE is involved in the anti-atherogenic reverse cholesterol transport pathway. Thus, TICE is an innovative drug target to reduce -cardiovascular diseases. © 2014 médecine/sciences – Inserm.

  20. Cholesterol - what to ask your doctor

    Science.gov (United States)

    ... your doctor; What to ask your doctor about cholesterol ... What is my cholesterol level? What should my cholesterol level be? What are HDL ("good") cholesterol and LDL ("bad") cholesterol? Does my cholesterol ...

  1. Structural basis of transport function in major facilitator superfamily protein from Trichoderma harzianum.

    Science.gov (United States)

    Chaudhary, Nitika; Sandhu, Padmani; Ahmed, Mushtaq; Akhter, Yusuf

    2017-02-01

    Trichothecenes are the sesquiterpenes secreted by Trichoderma spp. residing in the rhizosphere. These compounds have been reported to act as plant growth promoters and bio-control agents. The structural knowledge for the transporter proteins of their efflux remained limited. In this study, three-dimensional structure of Thmfs1 protein, a trichothecene transporter from Trichoderma harzianum, was homology modelled and further Molecular Dynamics (MD) simulations were used to decipher its mechanism. Fourteen transmembrane helices of Thmfs1 protein are observed contributing to an inward-open conformation. The transport channel and ligand binding sites in Thmfs1 are identified based on heuristic, iterative algorithm and structural alignment with homologous proteins. MD simulations were performed to reveal the differential structural behaviour occurring in the ligand free and ligand bound forms. We found that two discrete trichothecene binding sites are located on either side of the central transport tunnel running from the cytoplasmic side to the extracellular side across the Thmfs1 protein. Detailed analysis of the MD trajectories showed an alternative access mechanism between N and C-terminal domains contributing to its function. These results also demonstrate that the transport of trichodermin occurs via hopping mechanism in which the substrate molecule jumps from one binding site to another lining the transport tunnel. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. The actin cytoskeleton may control the polar distribution of an auxin transport protein

    Science.gov (United States)

    Muday, G. K.; Hu, S.; Brady, S. R.; Davies, E. (Principal Investigator)

    2000-01-01

    The gravitropic bending of plants has long been linked to the changes in the transport of the plant hormone auxin. To understand the mechanism by which gravity alters auxin movement, it is critical to know how polar auxin transport is initially established. In shoots, polar auxin transport is basipetal (i.e., from the shoot apex toward the base). It is driven by the basal localization of the auxin efflux carrier complex. One mechanism for localizing this efflux carrier complex to the basal membrane may be through attachment to the actin cytoskeleton. The efflux carrier protein complex is believed to consist of several polypeptides, including a regulatory subunit that binds auxin transport inhibitors, such as naphthylphthalamic acid (NPA). Several lines of experimentation have been used to determine if the NPA binding protein interacts with actin filaments. The NPA binding protein has been shown to partition with the actin cytoskeleton during detergent extraction. Agents that specifically alter the polymerization state of the actin cytoskeleton change the amount of NPA binding protein and actin recovered in these cytoskeletal pellets. Actin-affinity columns were prepared with polymers of actin purified from zucchini hypocotyl tissue. NPA binding activity was eluted in a single peak from the actin filament column. Cytochalasin D, which fragments the actin cytoskeleton, was shown to reduce polar auxin transport in zucchini hypocotyls. The interaction of the NPA binding protein with the actin cytoskeleton may localize it in one plane of the plasma membrane, and thereby control the polarity of auxin transport.

  3. Nucleocytoplasmic transport of nucleocapsid proteins of enveloped RNA viruses

    Directory of Open Access Journals (Sweden)

    Wahyu eWulan

    2015-06-01

    Full Text Available Most viruses with non-segmented single stranded RNA genomes complete their life cycle in the cytoplasm of infected cells. However, despite undergoing replication in the cytoplasm, the structural proteins of some of these RNA viruses localize to the nucleus at specific times in the virus life cycle, primarily early in infection. Limited evidence suggests that this enhances successful viral replication by interfering with or inhibiting the host antiviral response. Nucleocapsid proteins of RNA viruses have a well-established, essential cytoplasmic role in virus replication and assembly. Intriguingly, nucleocapsid proteins of some RNA viruses also localize to the nucleus/nucleolus of infected cells. Their nuclear function is less well understood although significant advances have been made in recent years. This review will focus on the nucleocapsid protein of cytoplasmic enveloped RNA viruses, including their localization to the nucleus/nucleolus and function therein. A greater understanding of the nuclear localization of nucleocapsid proteins has the potential to enhance therapeutic strategies as it can be a target for the development of live-attenuated vaccines or antiviral drugs.

  4. The comparison of the effects of standard 20 mg atorvastatin daily and 20 mg atorvastatin every other day on serum LDL-cholesterol and high sensitive C-reactive protein levels.

    Science.gov (United States)

    Keleş, Telat; Akar Bayram, Nihal; Kayhan, Tuğba; Canbay, Alper; Sahin, Deniz; Durmaz, Tahir; Ozdemir, Ozcan; Aydoğdu, Sinan; Diker, Erdem

    2008-12-01

    In this study, we aimed at comparing the effects of standard once daily 20 mg atorvastatin treatment with that of atorvastatin 20 mg administered every other day on serum lipids and high sensitive C-reactive protein (hs-CRP) levels. Sixty-one patients with serum total cholesterol levels of above 200 mg/dl and low density lipoprotein (LDL)--cholesterol levels of above 130 mg/dl were included in this prospective, randomized study. The patients were randomized into daily treatment of 20 mg atorvastatin (standard treatment) and 20 mg atorvastatin every other day (every other day treatment) groups. Before the treatment and at each visit, serum lipids and hs-CRP levels of all the patients were measured. Statistical analyses were performed Chi-square, unpaired t and two-way repeated measurements ANOVA tests. In the every other day treatment group, there was a 36.1% reduction in LDL-cholesterol levels by the end of first month (p0.05). The LDL cholesterol levels of the group receiving 20 mg atorvastatin every day was reduced by %41 by the end of 1 month (pevery other day, there was a 21% decrease in hs-CRP levels compared to the basal measurements at the end of first month (pevery day the decrease in hs-CRP levels at the end of one month was more striking (37%, p0.05). Alternate-day dosing of atorvastatin causes a significant lipid-lowering and antiinflammatory effects similar to that of daily administration and yet may provide some cost savings.

  5. ATPase and GTPase Tangos Drive Intracellular Protein Transport.

    Science.gov (United States)

    Shan, Shu-Ou

    2016-12-01

    The GTPase superfamily of proteins provides molecular switches to regulate numerous cellular processes. The 'GTPase switch' paradigm, in which external regulatory factors control the switch of a GTPase between 'on' and 'off' states, has been used to interpret the regulatory mechanism of many GTPases. However, recent work unveiled a class of nucleotide hydrolases that do not adhere to this classical paradigm. Instead, they use nucleotide-dependent dimerization cycles to regulate key cellular processes. In this review article, recent studies of dimeric GTPases and ATPases involved in intracellular protein targeting are summarized. It is suggested that these proteins can use the conformational plasticity at their dimer interface to generate multiple points of regulation, thereby providing the driving force and spatiotemporal coordination of complex cellular pathways. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Interaction of pathogens with host cholesterol metabolism.

    Science.gov (United States)

    Sviridov, Dmitri; Bukrinsky, Michael

    2014-10-01

    Pathogens of different taxa, from prions to protozoa, target cellular cholesterol metabolism to advance their own development and to impair host immune responses, but also causing metabolic complications, for example, atherosclerosis. This review describes recent findings of how pathogens do it. A common theme in interaction between pathogens and host cholesterol metabolism is pathogens targeting lipid rafts of the host plasma membrane. Many intracellular pathogens use rafts as an entry gate, taking advantage of the endocytic machinery and high abundance of outward-looking molecules that can be used as receptors. At the same time, disruption of the rafts' functional capacity, achieved by the pathogens through a number of various means, impairs the ability of the host to generate immune response, thus helping pathogen to thrive. Pathogens cannot synthesize cholesterol, and salvaging host cholesterol helps pathogens build advanced cholesterol-containing membranes and assembly platforms. Impact on cholesterol metabolism is not limited to the infected cells; proteins and microRNAs secreted by infected cells affect lipid metabolism systemically. Given an essential role that host cholesterol metabolism plays in pathogen development, targeting this interaction may be a viable strategy to fight infections, as well as metabolic complications of the infections.

  7. Genome, secretome and glucose transport highlight unique features of the protein production host Pichia pastoris

    Directory of Open Access Journals (Sweden)

    Mattanovich Diethard

    2009-06-01

    Full Text Available Abstract Background Pichia pastoris is widely used as a production platform for heterologous proteins and model organism for organelle proliferation. Without a published genome sequence available, strain and process development relied mainly on analogies to other, well studied yeasts like Saccharomyces cerevisiae. Results To investigate specific features of growth and protein secretion, we have sequenced the 9.4 Mb genome of the type strain DSMZ 70382 and analyzed the secretome and the sugar transporters. The computationally predicted secretome consists of 88 ORFs. When grown on glucose, only 20 proteins were actually secreted at detectable levels. These data highlight one major feature of P. pastoris, namely the low contamination of heterologous proteins with host cell protein, when applying glucose based expression systems. Putative sugar transporters were identified and compared to those of related yeast species. The genome comprises 2 homologs to S. cerevisiae low affinity transporters and 2 to high affinity transporters of other Crabtree negative yeasts. Contrary to other yeasts, P. pastoris possesses 4 H+/glycerol transporters. Conclusion This work highlights significant advantages of using the P. pastoris system with glucose based expression and fermentation strategies. As only few proteins and no proteases are actually secreted on glucose, it becomes evident that cell lysis is the relevant cause of proteolytic degradation of secreted proteins. The endowment with hexose transporters, dominantly of the high affinity type, limits glucose uptake rates and thus overflow metabolism as observed in S. cerevisiae. The presence of 4 genes for glycerol transporters explains the high specific growth rates on this substrate and underlines the suitability of a glycerol/glucose based fermentation strategy. Furthermore, we present an open access web based genome browser http://www.pichiagenome.org.

  8. Role of UBIAD1 in Intracellular Cholesterol Metabolism and Vascular Cell Calcification.

    Directory of Open Access Journals (Sweden)

    Sha Liu

    Full Text Available Vascular calcification is an important risk factor associated with mortality among patients with chronic kidney disease. Intracellular cholesterol metabolism is involved in the process of vascular cell calcification. In this study, we investigated the role of UbiA prenyltransferase domain containing 1 (UBIAD1 in intracellular cholesterol metabolism and vascular cell calcification, and identified its subcellular location. Primary human umbilical vein smooth muscle cells (HUVSMCs were incubated with either growth medium (1.4 mmol/L Pi or calcification medium (CM (3.0 mmol/L Pi. Under treatment with CM, HUVSMCs were further incubated with exogenous cholesterol, or menaquinone-4, a product of UBIAD1. The plasmid and small interfering RNA were transfected in HUVSMCs to alter the expression of UBIAD1. Matrix calcium quantitation, alkaline phosphatase activity, intracellular cholesterol level and menaquinone-4 level were measured. The expression of several genes involved in cholesterol metabolism were analyzed. Using an anti-UBIAD1 antibody, an endoplasmic reticulum marker and a Golgi marker, the subcellular location of UBIAD1 in HUVSMCs was analyzed. CM increased matrix calcium, alkaline phosphatase activity and intracellular cholesterol level, and reduced UBIAD1 expression and menaquinone-4 level. Addition of cholesterol contributed to increased matrix calcification and alkaline phosphatase activity in a dose-dependent manner. Elevated expression of UBIAD1 or menaquinone-4 in HUVSMCs treated with CM significantly reduced intracellular cholesterol level, matrix calcification and alkaline phosphatase activity, but increased menaquinone-4 level. Elevated expression of UBIAD1 or menaquinone-4 reduced the gene expression of sterol regulatory element-binding protein-2, and increased gene expression of ATP binding cassette transporters A1, which are in charge of cholesterol synthesis and efflux. UBIAD1 co-localized with the endoplasmic reticulum marker and

  9. Bile acid sequestrants for cholesterol

    Science.gov (United States)

    ... ency/patientinstructions/000787.htm Bile acid sequestrants for cholesterol To use the sharing features on this page, ... are medicines that help lower your LDL (bad) cholesterol . Too much cholesterol in your blood can stick ...

  10. A Closer Look at Cardioprotective Function of HDL: Revise the HDL – Cholesterol Hypothesis?

    Directory of Open Access Journals (Sweden)

    Anna Meiliana

    2014-04-01

    Full Text Available BACKGROUND: The strong inverse association of plasma levels of high-density lipoprotein (HDL cholesterol with coronary heart disease (CHD found in human epidemiological studies led to the development of the ‘HDL cholesterol hypothesis’, which posits that intervention to raise HDL cholesterol will result in reduced risk of CHD. A number of recent developments have brought the potential protective role of HDL into question. Several clinical trials of agents that substantially raise HDL-C have been demonstrated to not reduce CHD event rates. CONTENT: For decades, HDL and HDL-cholesterol (HDL-C levels were viewed as synonymous, and modulation of HDL-C levels by drug therapy held great promise for the prevention and treatment of cardiovascular disease. Nevertheless, recent failures of drugs that raise HDL-C to reduce cardiovascular risk and the now greater understanding of the complexity of HDL composition and biology have prompted researchers in the field to redefine HDL. As such, the focus of HDL has now started to shift away from a cholesterol-centric view toward HDL particle number, subclasses, and other alternative metrics of HDL. Many of the recently discovered functions of HDL are, in fact, not strictly conferred by its ability to promote cholesterol flux but by the other molecules it transports, including a diverse set of proteins, small RNAs, hormones, carotenoids, vitamins, and bioactive lipids. Based on HDL’s ability to interact with almost all cells and deliver fat-soluble cargo, HDL has the remarkable capacity to affect a wide variety of endocrine-like systems. SUMMARY: There is a significant need to redefine HDL and its benefit. HDL transports a diverse set of functional proteins, including many binding proteins. HDL transports and deliver vitamins, carotenoids, and other small molecules. Moreover, HDL transports hormones, steroids and bile acids, and can modulate multiple endocrine pathways. HDLs also transport and deliver micro

  11. A critical role for the cholesterol-associated proteolipids PLP and M6B in myelination of the central nervous system.

    Science.gov (United States)

    Werner, Hauke B; Krämer-Albers, Eva-Maria; Strenzke, Nicola; Saher, Gesine; Tenzer, Stefan; Ohno-Iwashita, Yoshiko; De Monasterio-Schrader, Patricia; Möbius, Wiebke; Moser, Tobias; Griffiths, Ian R; Nave, Klaus-Armin

    2013-04-01

    The formation of central nervous system myelin by oligodendrocytes requires sterol synthesis and is associated with a significant enrichment of cholesterol in the myelin membrane. However, it is unknown how oligodendrocytes concentrate cholesterol above the level found in nonmyelin membranes. Here, we demonstrate a critical role for proteolipids in cholesterol accumulation. Mice lacking the most abundant myelin protein, proteolipid protein (PLP), are fully myelinated, but PLP-deficient myelin exhibits a reduced cholesterol content. We therefore hypothesized that "high cholesterol" is not essential in the myelin sheath itself but is required for an earlier step of myelin biogenesis that is fully compensated for in the absence of PLP. We also found that a PLP-homolog, glycoprotein M6B, is a myelin component of low abundance. By targeting the Gpm6b-gene and crossbreeding, we found that single-mutant mice lacking either PLP or M6B are fully myelinated, while double mutants remain severely hypomyelinated, with enhanced neurodegeneration and premature death. As both PLP and M6B bind membrane cholesterol and associate with the same cholesterol-rich oligodendroglial membrane microdomains, we suggest a model in which proteolipids facilitate myelination by sequestering cholesterol. While either proteolipid can maintain a threshold level of cholesterol in the secretory pathway that allows myelin biogenesis, lack of both proteolipids results in a severe molecular imbalance of prospective myelin membrane. However, M6B is not efficiently sorted into mature myelin, in which it is 200-fold less abundant than PLP. Thus, only PLP contributes to the high cholesterol content of myelin by association and co-transport. Copyright © 2013 Wiley Periodicals, Inc.

  12. Alterations in protein transport events in rat liver after estrogen treatment

    International Nuclear Information System (INIS)

    Goldsmith, M.A.; Jones, A.L.; Underdown, B.J.; Schiff, J.M.

    1987-01-01

    The effects of 17α-ethynylestradiol (EE) treatment on the hepatic processing of rat polymeric immunoglobulin A (IgA) and human asialoorosomucoid (ASOr) were studied. After 5 days of treatment with EE (5 mg/kg) or solvent alone, male rats were anesthetized and injected with tracer doses of the test proteins. Bile flow rates had been reduced by >60% in the EE-treated animals. A previously reported radiolabeling strategy was used to monitor both the transport of intact protein to bile and the degradation of protein in lysosomes. Transport of intact IgA to bile was reduced by 43%, with transport peaking 27 min later in EE-treated animals compared with controls. There was a corresponding impairment of uptake of labeled IgA from blood. EE induced no kinetic change in the uptake or processing of ASOr. However, there was an increase in the proportion of ASOr reaching bile intact from 3% to 15-23% of the injected dose. The data indicate that EE disables the transport pathway for IgA and causes a partial change in the routing of ASOr after endocytosis in favor of direct transport to the bile canaliculus. These findings may have implications for the importance of membrane composition in protein transport events

  13. Taurine ameliorates cholesterol metabolism by stimulating bile acid production in high-cholesterol-fed rats.

    Science.gov (United States)

    Murakami, Shigeru; Fujita, Michiko; Nakamura, Masakazu; Sakono, Masanobu; Nishizono, Shoko; Sato, Masao; Imaizumi, Katsumi; Mori, Mari; Fukuda, Nobuhiro

    2016-03-01

    This study was designed to investigate the effects of dietary taurine on cholesterol metabolism in high-cholesterol-fed rats. Male Sprague-Dawley rats were randomly divided into two dietary groups (n = 6 in each group): a high-cholesterol diet containing 0.5% cholesterol and 0.15% sodium cholate, and a high-cholesterol diet with 5% (w/w) taurine. The experimental diets were given for 2 weeks. Taurine supplementation reduced the serum and hepatic cholesterol levels by 37% and 32%, respectively. Faecal excretion of bile acids was significantly increased in taurine-treated rats, compared with untreated rats. Biliary bile acid concentrations were also increased by taurine. Taurine supplementation increased taurine-conjugated bile acids by 61% and decreased glycine-conjugated bile acids by 53%, resulting in a significant decrease in the glycine/taurine (G/T) ratio. Among the taurine-conjugated bile acids, cholic acid and deoxycholic acid were significantly increased. In the liver, taurine supplementation increased the mRNA expression and enzymatic activity of hepatic cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme for bile acid synthesis, by three- and two-fold, respectively. Taurine also decreased the enzymatic activity of acyl-CoA:cholesterol acyltransferase (ACAT) and microsomal triglyceride transfer protein (MTP). These observations suggest that taurine supplementation increases the synthesis and excretion of taurine-conjugated bile acids and stimulates the catabolism of cholesterol to bile acid by elevating the expression and activity of CYP7A1. This may reduce cholesterol esterification and lipoprotein assembly for very low density lipoprotein (VLDL) secretion, leading to reductions in the serum and hepatic cholesterol levels. © 2016 John Wiley & Sons Australia, Ltd.

  14. Choline transport via choline transporter-like protein 1 in conditionally immortalized rat syncytiotrophoblast cell lines TR-TBT.

    Science.gov (United States)

    Lee, N-Y; Choi, H-M; Kang, Y-S

    2009-04-01

    Choline is an essential nutrient for phospholipids and acetylcholine biosynthesis in normal development of fetus. In the present study, we investigated the functional characteristics of choline transport system and inhibitory effect of cationic drugs on choline transport in rat conditionally immortalized syncytiotrophoblast cell line (TR-TBT). Choline transport was weakly Na(+) dependent and significantly influenced by extracellular pH and by membrane depolarization. The transport process of choline is saturable with Michaelis-Menten constants (K(m)) of 68microM and 130microM in TR-TBT 18d-1 and TR-TBT 18d-2 respectively. Choline uptake in the cells was inhibited by unlabeled choline and hemicholinium-3 as well as various organic cations including guanidine, amiloride and acetylcholine. However, the prototypical organic cation tetraethylammonium and cimetidine showed very little inhibitory effect of choline uptake in TR-TBT cells. RT-PCR revealed that choline transporter-like protein 1 (CTL1) and organic cation transporter 2 (OCT2) are expressed in TR-TBT cells. The transport properties of choline in TR-TBT cells were similar or identical to that of CTL1 but not OCT2. CTL1 was also detected in human placenta. In addition, several cationic drugs such as diphenhydramine and verapamil competitively inhibited choline uptake in TR-TBT 18d-1 with K(i) of 115microM and 55microM, respectively. Our results suggest that choline transport system, which has intermediate affinity and weakly Na(+) dependent, in TR-TBT seems to occur through a CTL1 and this system may have relevance with the uptake of pharmacologically important organic cation drugs.

  15. Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway.

    Science.gov (United States)

    Xu, Xiaolin; Li, Qian; Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian; Wang, Yiqing

    2013-11-15

    Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Curcumin inhibits cholesterol uptake in Caco-2 cells by down-regulation of NPC1L1 expression

    Directory of Open Access Journals (Sweden)

    Duan Rui-Dong

    2010-04-01

    Full Text Available Abstract Background Curcumin is a polyphenol and the one of the principle curcuminoids of the spice turmeric. Its antioxidant, anti-cancer and anti-inflammatory effects have been intensively studied. Previous in vivo studies showed that administration of curcumin also decreased cholesterol levels in the blood, and the effects were considered to be related to upregulation of LDL receptor. However, since plasma cholesterol levels are also influenced by the uptake of cholesterol in the gut, which is mediated by a specific transporter Niemann-Pick Cl-like 1 (NPC1L1 protein, the present study is to investigate whether curcumin affects cholesterol uptake in the intestinal Caco-2 cells. Methods Caco-2 cells were cultured to confluence. The micelles composed of bile salt, monoolein, and 14C-cholesterol were prepared. We first incubated the cells with the micelles in the presence and absence of ezetimibe, the specific inhibitor of NPC1L1, to see whether the uptake of the cholesterol in the cells was mediated by NPC1L1. We then pretreated the cells with curcumin at different concentrations for 24 h followed by examination of the changes of cholesterol uptake in these curcumin-treated cells. Finally we determined whether curcumin affects the expression of NPC1L1 by both Western blot analysis and qPCR quantification. Results We found that the uptake of radioactive cholesterol in Caco-2 cells was inhibited by ezetimibe in a dose-dependent manner. The results indicate that the uptake of cholesterol in this study was mediated by NPC1L1. We then pretreated the cells with 25-100 μM curcumin for 24 h and found that such a treatment dose-dependently inhibited cholesterol uptake with 40% inhibition obtained by 100 μM curcumin. In addition, we found that the curcumin-induced inhibition of cholesterol uptake was associated with significant decrease in the levels of NPC1L1 protein and NPC1L1 mRNA, as analyzed by Western blot and qPCR, respectively. Conclusion

  17. Curcumin inhibits cholesterol uptake in Caco-2 cells by down-regulation of NPC1L1 expression.

    Science.gov (United States)

    Feng, Dan; Ohlsson, Lena; Duan, Rui-Dong

    2010-04-19

    Curcumin is a polyphenol and the one of the principle curcuminoids of the spice turmeric. Its antioxidant, anti-cancer and anti-inflammatory effects have been intensively studied. Previous in vivo studies showed that administration of curcumin also decreased cholesterol levels in the blood, and the effects were considered to be related to upregulation of LDL receptor. However, since plasma cholesterol levels are also influenced by the uptake of cholesterol in the gut, which is mediated by a specific transporter Niemann-Pick Cl-like 1 (NPC1L1) protein, the present study is to investigate whether curcumin affects cholesterol uptake in the intestinal Caco-2 cells. Caco-2 cells were cultured to confluence. The micelles composed of bile salt, monoolein, and 14C-cholesterol were prepared. We first incubated the cells with the micelles in the presence and absence of ezetimibe, the specific inhibitor of NPC1L1, to see whether the uptake of the cholesterol in the cells was mediated by NPC1L1. We then pretreated the cells with curcumin at different concentrations for 24 h followed by examination of the changes of cholesterol uptake in these curcumin-treated cells. Finally we determined whether curcumin affects the expression of NPC1L1 by both Western blot analysis and qPCR quantification. We found that the uptake of radioactive cholesterol in Caco-2 cells was inhibited by ezetimibe in a dose-dependent manner. The results indicate that the uptake of cholesterol in this study was mediated by NPC1L1. We then pretreated the cells with 25-100 muM curcumin for 24 h and found that such a treatment dose-dependently inhibited cholesterol uptake with 40% inhibition obtained by 100 muM curcumin. In addition, we found that the curcumin-induced inhibition of cholesterol uptake was associated with significant decrease in the levels of NPC1L1 protein and NPC1L1 mRNA, as analyzed by Western blot and qPCR, respectively. Curcumin inhibits cholesterol uptake through suppression of NPC1L1

  18. Sterol transfer between cyclodextrin and membranes: similar but not identical mechanism to NPC2-mediated cholesterol transfer.

    Science.gov (United States)

    McCauliff, Leslie A; Xu, Zhi; Storch, Judith

    2011-08-30

    Niemann--Pick C disease is an inherited disorder in which cholesterol and other lipids accumulate in the late endosomal/lysosomal compartment. Recently, cyclodextrins (CD) have been shown to reduce symptoms and extend lifespan in animal models of the disease. In the present studies we examined the mechanism of sterol transport by CD using in vitro model systems and fluorescence spectroscopy and NPC2-deficient fibroblasts. We demonstrate that cholesterol transport from the lysosomal cholesterol-binding protein NPC2 to CD occurs via aqueous diffusional transfer and is very slow; the rate-limiting step appears to be dissociation of cholesterol from NPC2, suggesting that specific interactions between NPC2 and CD do not occur. In contrast, the transfer rate of the fluorescent cholesterol analogue dehydroergosterol (DHE) from CD to phospholipid membranes is very rapid and is directly proportional to the acceptor membrane concentration, as is DHE transfer from membranes to CD. Moreover, CD dramatically increases the rate of sterol transfer between membranes, with rates that can approach those mediated by NPC2. The results suggest that sterol transfer from CD to membranes occurs by a collisional transfer mechanism involving direct interaction of CD with membranes, similar to that shown previously for NPC2. For CD, however, absolute rates are slower compared to NPC2 for a given concentration, and the lysosomal phospholipid lysobisphosphatidic acid (LBPA) does not stimulate rates of sterol transfer between membranes and CD. As expected from the apparent absence of interaction between CD and NPC2, the addition of CD to NPC2-deficient fibroblasts rapidly rescued the cholesterol accumulation phenotype. Thus, the recent observations of CD efficacy in mouse models of NPC disease are likely the result of CD enhancement of cholesterol transport between membranes, with rapid sterol transfer occurring during CD--membrane interactions.

  19. Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na+/K+-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes

    Directory of Open Access Journals (Sweden)

    Stefanie Klinger

    2018-03-01

    Full Text Available Background: Beneficial effects of Resveratrol (RSV have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min in Ussing chambers (functional studies and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs. Results: RSV reduced alanine and glucose-induced short circuit currents (ΔIsc and influenced forskolin-induced ΔIsc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1, AMP-activated protein kinase (AMPK, protein kinase A substrates (PKA-S and liver kinase B1 (LKB1 increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1 and (phosphorylated Na+/H+-exchanger 3 (NHE3 did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.

  20. Plasma membrane microdomains regulate turnover of transport proteins in yeast

    Czech Academy of Sciences Publication Activity Database

    Grossmann, G.; Malínský, Jan; Stahlschmidt, W.; Loibl, M.; Weig-Meckl, I.; Frommer, W.B.; Opekarová, Miroslava; Tanner, W.

    2008-01-01

    Roč. 183, č. 6 (2008), s. 1075-1088 ISSN 0021-9525 R&D Projects: GA ČR GA204/06/0009; GA ČR GA204/07/0133; GA ČR GC204/08/J024 Institutional research plan: CEZ:AV0Z50390703; CEZ:AV0Z50200510 Keywords : Lithium acetate * Membrane compartment of Can1 * Monomeric red fluorescent protein Subject RIV: EA - Cell Biology Impact factor: 9.120, year: 2008

  1. How to Lower Cholesterol

    Science.gov (United States)

    ... includes high triglyceride levels, low HDL (good) cholesterol levels, and being overweight with a large waist measurement (more than 40 inches for men and more than 35 inches for women). Physical Activity. Everyone should get regular physical activity (30 minutes ...

  2. Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xiaolin [Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai 200032 (China); Li, Qian [Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai (China); Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian [Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai 200032 (China); Wang, Yiqing [Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai 200032 (China)

    2013-11-15

    Highlights: •Arctigenin enhanced cholesterol efflux in oxLDL-loaded THP-1 macrophages. •The expression of ABCA1, ABCG1 and apoE was upregulated in arctigenin-treated cells. •Arctigenin promoted the expression of PPAR-γ and LXR-α. •Inhibition of PPAR-γ or LXR-α reversed arctigenin-mediated biological effects. •Arctigenin promotes cholesterol efflux via activation of PPAR-γ/LXR-α/ABCA1 pathway. -- Abstract: Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α.

  3. Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway

    International Nuclear Information System (INIS)

    Xu, Xiaolin; Li, Qian; Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian; Wang, Yiqing

    2013-01-01

    Highlights: •Arctigenin enhanced cholesterol efflux in oxLDL-loaded THP-1 macrophages. •The expression of ABCA1, ABCG1 and apoE was upregulated in arctigenin-treated cells. •Arctigenin promoted the expression of PPAR-γ and LXR-α. •Inhibition of PPAR-γ or LXR-α reversed arctigenin-mediated biological effects. •Arctigenin promotes cholesterol efflux via activation of PPAR-γ/LXR-α/ABCA1 pathway. -- Abstract: Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α

  4. Endogenous Cholesterol Excretion Is Negatively Associated With Carotid Intima-Media Thickness in Humans.

    Science.gov (United States)

    Lin, Xiaobo; Racette, Susan B; Ma, Lina; Wallendorf, Michael; Dávila-Román, Victor G; Ostlund, Richard E

    2017-12-01

    Epidemiological studies strongly suggest that lipid factors independent of low-density lipoprotein cholesterol contribute significantly to cardiovascular disease risk. Because circulating lipoproteins comprise only a small fraction of total body cholesterol, the mobilization and excretion of cholesterol from plasma and tissue pools may be an important determinant of cardiovascular disease risk. Our hypothesis is that fecal excretion of endogenous cholesterol is protective against atherosclerosis. Cholesterol metabolism and carotid intima-media thickness were quantitated in 86 nondiabetic adults. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d 7 solubilized in a lipid emulsion and dietary cholesterol by cholesterol-d 5 and the nonabsorbable stool marker sitostanol-d 4 . Plasma and stool samples were collected while subjects consumed a cholesterol- and phytosterol-controlled metabolic kitchen diet and were analyzed by mass spectrometry. Carotid intima-media thickness was negatively correlated with fecal excretion of endogenous cholesterol ( r =-0.426; P cholesterol ( r =-0.472; P ≤0.0001), and daily percent excretion of cholesterol from the rapidly mixing cholesterol pool ( r =-0.343; P =0.0012) and was positively correlated with percent cholesterol absorption ( r =+0.279; P =0.0092). In a linear regression model controlling for age, sex, systolic blood pressure, hemoglobin A1c, low-density lipoprotein, high-density lipoprotein cholesterol, and statin drug use, fecal excretion of endogenous cholesterol remained significant ( P =0.0008). Excretion of endogenous cholesterol is strongly, independently, and negatively associated with carotid intima-media thickness. The reverse cholesterol transport pathway comprising the intestine and the rapidly mixing plasma, and tissue cholesterol pool could be an unrecognized determinant of cardiovascular disease risk not reflected in circulating lipoproteins. Further work is needed to relate measures of

  5. Phloem RNA-binding proteins as potential components of the long-distance RNA transport system.

    Directory of Open Access Journals (Sweden)

    VICENTE ePALLAS

    2013-05-01

    Full Text Available RNA-binding proteins (RBPs govern a myriad of different essential processes in eukaryotic cells. Recent evidence reveals that apart from playing critical roles in RNA metabolism and RNA transport, RBPs perform a key function in plant adaption to various environmental conditions. Long distance RNA transport occurs in land plants through the phloem, a conducting tissue that integrates the wide range of signalling pathways required to regulate plant development and response to stress processes. The macromolecules in the phloem pathway vary greatly and include defence proteins, transcription factors, chaperones acting in long distance trafficking, and RNAs (mRNAs, siRNAs and miRNAs. How these RNA molecules translocate through the phloem is not well understood, but recent evidence indicates the presence of translocatable RNA-binding proteins in the phloem, which act as potential components of long distance RNA transport system. This review updates our knowledge on the characteristics and functions of RBPs present in the phloem.

  6. Reference intervals for serum total cholesterol, HDL cholesterol and ...

    African Journals Online (AJOL)

    Reference intervals of total cholesterol, HDL cholesterol and non-HDL cholesterol concentrations were determined on 309 blood donors from an urban and peri-urban population of Botswana. Using non-parametric methods to establish 2.5th and 97.5th percentiles of the distribution, the intervals were: total cholesterol 2.16 ...

  7. Type 2 diabetes mellitus is associated with differential effects on plasma cholesteryl ester transfer protein and phospholipid transfer protein activities and concentrations

    NARCIS (Netherlands)

    Dullaart, RPF; De Vries, R; Scheek, L; Borggreve, SE; Van Gent, T; Dallinga-Thie, GM; Ito, M; Nagano, M; Sluiter, WJ; Hattori, H; Van Tol, A

    Background: Human plasma contains two lipid transfer proteins, cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP), which are crucial in reverse cholesterol transport. Methods: Plasma CETP and PLTP activity levels and concentrations in 16 type 2 diabetic patients and

  8. Cholesterol in unusual places

    International Nuclear Information System (INIS)

    Kucerka, N; Nieh, M P; Marquardt, D; Harroun, T A; Wassail, S R; Katsaras, J

    2010-01-01

    Cholesterol is an essential component of mammalian cells, and is required for building and maintaining cell membranes, regulating their fluidity, and possibly acting as an antioxidant. Cholesterol has also been implicated in cell signaling processes, where it has been suggested that it triggers the formation of lipid rafts in the plasma membrane. Aside from cholesterol's physiological roles, what is also becoming clear is its poor affinity for lipids with unsaturated fatty acids as opposed to saturated lipids, such as sphingomyelin with which it forms rafts. We previously reported the location of cholesterol in membranes with varying degrees of acyl chain unsaturation as determined by neutron diffraction studies (Harroun et al 2006 Biochemistry 45, 1227; Harroun et al 2008 Biochemistry 47, 7090). In bilayers composed of phosphatidylcholine (PC) molecules with a saturated acyl chain at the sn-1 position or a monounsaturated acyl chain at both sn-1 and sn-2 positions, cholesterol was found in its much-accepted 'upright' position. However, in dipolyunsaturated 1,2-diarachidonyl phosphatidylcholine (20:4-20:4PC) membranes the molecule was found sequestered in the center of the bilayers. In further experiments, mixing l-palmitoyl-2-oleoyl phosphatidylcholine (16:0-18:1 PC) with 20:4-20:4PC resulted in cholesterol reverting to its upright orientation at approximately 40 mol% 16:0-18:1 PC. Interestingly, the same effect was achieved with only 5 mol% 1,2-dimyristoyl phosphatidylchoile (14:0-14:0PC).

  9. Cholesterol in unusual places

    Energy Technology Data Exchange (ETDEWEB)

    Kucerka, N; Nieh, M P; Marquardt, D; Harroun, T A; Wassail, S R; Katsaras, J, E-mail: John.Katsaras@nrc.gc.ca, E-mail: Norbert.Kucerka@nrc.gc.ca

    2010-11-01

    Cholesterol is an essential component of mammalian cells, and is required for building and maintaining cell membranes, regulating their fluidity, and possibly acting as an antioxidant. Cholesterol has also been implicated in cell signaling processes, where it has been suggested that it triggers the formation of lipid rafts in the plasma membrane. Aside from cholesterol's physiological roles, what is also becoming clear is its poor affinity for lipids with unsaturated fatty acids as opposed to saturated lipids, such as sphingomyelin with which it forms rafts. We previously reported the location of cholesterol in membranes with varying degrees of acyl chain unsaturation as determined by neutron diffraction studies (Harroun et al 2006 Biochemistry 45, 1227; Harroun et al 2008 Biochemistry 47, 7090). In bilayers composed of phosphatidylcholine (PC) molecules with a saturated acyl chain at the sn-1 position or a monounsaturated acyl chain at both sn-1 and sn-2 positions, cholesterol was found in its much-accepted 'upright' position. However, in dipolyunsaturated 1,2-diarachidonyl phosphatidylcholine (20:4-20:4PC) membranes the molecule was found sequestered in the center of the bilayers. In further experiments, mixing l-palmitoyl-2-oleoyl phosphatidylcholine (16:0-18:1 PC) with 20:4-20:4PC resulted in cholesterol reverting to its upright orientation at approximately 40 mol% 16:0-18:1 PC. Interestingly, the same effect was achieved with only 5 mol% 1,2-dimyristoyl phosphatidylchoile (14:0-14:0PC).

  10. Astragalus polysaccharides lowers plasma cholesterol through mechanisms distinct from statins.

    Directory of Open Access Journals (Sweden)

    Yunjiu Cheng

    Full Text Available To determine the efficacy and underlying mechanism of Astragalus polysaccharides (APS on plasma lipids in hypercholesterolemia hamsters. The effect of APS (0.25 g/kg/d on plasma and liver lipids, fecal bile acids and neutral sterol, cholesterol absorption and synthesis, HMG-CoA reductase activity, and gene and protein expressions in the liver and small intestine was investigated in twenty-four hypercholesterolemia hamsters. Treatment periods lasted for three months. APS significantly lowered plasma total cholesterol by 45.8%, triglycerides by 30%, and low-density lipoprotein-cholesterol by 47.4%, comparable to simvastatin. Further examinations revealed that APS reduced total cholesterol and triglycerides in the liver, increased fecal bile acid and neutral sterol excretion, inhibited cholesterol absorption, and by contrast, increased hepatic cholesterol synthesis and HMG-CoA reductase activity. Plasma total cholesterol or low-density lipoprotein-cholesterol levels were significantly correlated with cholesterol absorption rates. APS up-regulated cholesterol-7α-hydroxylase and LDL-receptor gene expressions. These new findings identify APS as a potential natural cholesterol lowering agent, working through mechanisms distinct from statins.

  11. Comparative genomic analyses of transport proteins encoded within the genomes of Leptospira species.

    Science.gov (United States)

    Buyuktimkin, Bora; Saier, Milton H

    2015-11-01

    Select species of the bacterial genus Leptospira are causative agents of leptospirosis, an emerging global zoonosis affecting nearly one million people worldwide annually. We examined two Leptospira pathogens, Leptospira interrogans serovar Lai str. 56601 and Leptospira borgpetersenii serovar Hardjo-bovis str. L550, as well as the free-living leptospiral saprophyte, Leptospira biflexa serovar Patoc str. 'Patoc 1 (Ames)'. The transport proteins of these leptospires were identified and compared using bioinformatics to gain an appreciation for which proteins may be related to pathogenesis and saprophytism. L. biflexa possesses a disproportionately high number of secondary carriers for metabolite uptake and environmental adaptability as well as an increased number of inorganic cation transporters providing ionic homeostasis and effective osmoregulation in a rapidly changing environment. L. interrogans and L. borgpetersenii possess far fewer transporters, but those that they have are remarkably similar, with near-equivalent representation in most transporter families. These two Leptospira pathogens also possess intact sphingomyelinases, holins, and virulence-related outer membrane porins. These virulence-related factors, in conjunction with decreased transporter substrate versatility, indicate that pathogenicity was accompanied by progressively narrowing ecological niches and the emergence of a limited set of proteins responsible for host invasion. The variability of host tropism and mortality rates by infectious leptospires suggests that small differences in individual sets of proteins play important physiological and pathological roles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Comparative analyses of transport proteins encoded within the genomes of Leptospira species.

    Science.gov (United States)

    Buyuktimkin, Bora; Saier, Milton H

    2016-09-01

    Select species of the bacterial genus Leptospira are causative agents of leptospirosis, an emerging global zoonosis affecting nearly one million people worldwide annually. We examined two Leptospira pathogens, Leptospira interrogans serovar Lai str. 56601 and Leptospira borgpetersenii serovar Hardjo-bovis str. L550, as well as the free-living leptospiral saprophyte, Leptospira biflexa serovar Patoc str. 'Patoc 1 (Ames)'. The transport proteins of these leptospires were identified and compared using bioinformatics to gain an appreciation for which proteins may be related to pathogenesis and saprophytism. L. biflexa possesses a disproportionately high number of secondary carriers for metabolite uptake and environmental adaptability as well as an increased number of inorganic cation transporters providing ionic homeostasis and effective osmoregulation in a rapidly changing environment. L. interrogans and L. borgpetersenii possess far fewer transporters, but those that they all have are remarkably similar, with near-equivalent representation in most transporter families. These two Leptospira pathogens also possess intact sphingomyelinases, holins, and virulence-related outer membrane porins. These virulence-related factors, in conjunction with decreased transporter substrate versatility, indicate that pathogenicity arose in Leptospira correlating to progressively narrowing ecological niches and the emergence of a limited set of proteins responsible for host invasion. The variability of host tropism and mortality rates by infectious leptospires suggests that small differences in individual sets of proteins play important physiological and pathological roles. Copyright © 2016. Published by Elsevier Ltd.

  13. Fluoroquinolone resistance protein NorA of Staphylococcus aureus is a multidrug efflux transporter.

    OpenAIRE

    Neyfakh, A A; Borsch, C M; Kaatz, G W

    1993-01-01

    The gene of the Staphylococcus aureus fluoroquinolone efflux transporter protein NorA confers resistance to a number of structurally dissimilar drugs, not just to fluoroquinolones, when it is expressed in Bacillus subtilis. NorA provides B. subtilis with resistance to the same drugs and to a similar extent as the B. subtilis multidrug transporter protein Bmr does. NorA and Bmr share 44% sequence similarity. Both the NorA- and Bmr-conferred resistances can be completely reversed by reserpine.

  14. Mutations that alter the transport function of the LamB protein in Escherichia coli.

    OpenAIRE

    Wandersman, C; Schwartz, M

    1982-01-01

    Some Escherichia coli K-12 lamB mutants, those producing reduced amounts of LamB protein (one-tenth the wild type amount), grow normally on dextrins but transport maltose when present at a concentration of 1 microM at about one-tenth the normal rate. lamB Dex- mutants were found as derivatives of these strains. These Dex- mutants are considerably impaired in the transport of maltose at low concentrations (below 10 microM), and they have a structurally altered LamB protein which is impaired in...

  15. Light-fuelled transport of large dendrimers and proteins.

    Science.gov (United States)

    Koskela, Jenni E; Liljeström, Ville; Lim, Jongdoo; Simanek, Eric E; Ras, Robin H A; Priimagi, Arri; Kostiainen, Mauri A

    2014-05-14

    This work presents a facile water-based supramolecular approach for light-induced surface patterning. The method is based upon azobenzene-functionalized high-molecular weight triazine dendrimers up to generation 9, demonstrating that even very large globular supramolecular complexes can be made to move in response to light. We also demonstrate light-fuelled macroscopic movements in native biomolecules, showing that complexes of apoferritin protein and azobenzene can effectively form light-induced surface patterns. Fundamentally, the results establish that thin films comprising both flexible and rigid globular particles of large diameter can be moved with light, whereas the presented material concepts offer new possibilities for the yet marginally explored biological applications of azobenzene surface patterning.

  16. Quantitative comparison of the efficacy of various compounds in lowering intracellular cholesterol levels in Niemann-Pick type C fibroblasts.

    Directory of Open Access Journals (Sweden)

    Zachary T Wehrmann

    Full Text Available Niemann-Pick Type C disease (NPC is a lethal, autosomal recessive disorder caused by mutations in the NPC1 and NPC2 cholesterol transport proteins. NPC's hallmark symptoms include an accumulation of unesterified cholesterol and other lipids in the late endosomal and lysosomal cellular compartments, causing progressive neurodegeneration and death. Although the age of onset may vary in those affected, NPC most often manifests in juveniles, and is usually fatal before adolescence. In this study, we investigated the effects of various drugs, many of which modify the epigenetic control of NPC1/NPC2 gene expression, in lowering the otherwise harmful elevated intracellular cholesterol levels in NPC cells. Our studies utilized a previously described image analysis technique, which allowed us to make quantitative comparisons of the efficacy of these drugs in lowering cholesterol levels in a common NPC1 mutant model. Of the drugs analyzed, several that have been previously studied (vorinostat, panobinostat, and β-cyclodextrin significantly lowered the relative amount of unesterified cellular cholesterol, consistent with earlier observations. In addition, a novel potential treatment, rapamycin, likewise alleviated the NPC phenotype. We also studied combinations of effective compounds with β-cyclodextrin; the addition of β-cyclodextrin significantly enhanced the cholesterol-lowering activity of vorinostat and panobinostat, but had mixed effects with rapamycin. Collectively, these results may provide a basis for the eventual development of improved NPC therapies.

  17. Molecular interactions between bile salts, phospholipids and cholesterol : relevance to bile formation, cholesterol crystallization and bile salt toxicity

    NARCIS (Netherlands)

    Moschetta, Antonio

    2001-01-01

    Cholesterol is a nonpolar lipid dietary constituent, absorbed from the small intestine, transported in blood and taken up by the liver. In bile, the sterol is solubilized in mixed micelles by bile salts and phospholipids. In case of supersaturation, cholesterol is kept in vesicles with phospholipid

  18. The role of cholesterol in the association of endoplasmic reticulum membranes with mitochondria

    International Nuclear Information System (INIS)

    Fujimoto, Michiko; Hayashi, Teruo; Su, Tsung-Ping

    2012-01-01

    Highlights: ► The endoplasmic reticulum subdomain termed MAM associates with mitochondria. ► The biophysical role of lipids in the MAM–mitochondria association is unknown. ► The in vitro membrane association assay was used to examine the role of lipids. ► Cholesterol was found to negatively regulate the association. -- Abstract: The unique endoplasmic reticulum (ER) subdomain termed the mitochondria-associated ER membrane (MAM) engages the physical connection between the ER and the mitochondrial outer membrane and plays a role in regulating IP 3 receptor-mediated Ca 2+ influx and the phospholipid transport between the two organelles. The MAM contains certain signaling and membrane-tethering proteins but also lipids including cholesterol. The biophysical role of lipids at the MAM, specifically in the physical interaction between the MAM of the ER and mitochondria, remains not totally clarified. Here we employed the in vitro membrane association assay to investigate the role of cholesterol in the association between MAMs and mitochondria. The purified MAMs and mitochondria were mixed in vitro in a test tube and then the physical association of the two subcellular organelles was quantified indirectly by measuring the presence of the MAM-specific protein sigma-1 receptors in the mitochondria fraction. Purified MAMs contained free cholesterol approximately 7 times higher than that in microsomes. We found that depletion of cholesterol in MAMs with methyl-β-cyclodextrin (MβC) significantly increases the association between MAMs and mitochondria, whereas MβC saturated with cholesterol does not change the association. 14 C-Serine pulse-labeling demonstrated that the treatment of living cells with MβC decreases the level of de novo synthesized 14 C-phosphatidylserine (PtSer) and concomitantly increases greatly the synthesis of 14 C-phosphatidylethanolamine (PtEt). Apparently, cholesterol depletion increased the PtSer transport from MAMs to mitochondria. Our

  19. The role of cholesterol in the association of endoplasmic reticulum membranes with mitochondria

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Michiko [Cellular Stress Signaling Unit, Integrative Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224 (United States); Hayashi, Teruo, E-mail: thayashi@mail.nih.gov [Cellular Stress Signaling Unit, Integrative Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224 (United States); Su, Tsung-Ping, E-mail: tsu@intra.nida.nih.gov [Cellular Pathobiology Section, Integrative Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224 (United States)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer The endoplasmic reticulum subdomain termed MAM associates with mitochondria. Black-Right-Pointing-Pointer The biophysical role of lipids in the MAM-mitochondria association is unknown. Black-Right-Pointing-Pointer The in vitro membrane association assay was used to examine the role of lipids. Black-Right-Pointing-Pointer Cholesterol was found to negatively regulate the association. -- Abstract: The unique endoplasmic reticulum (ER) subdomain termed the mitochondria-associated ER membrane (MAM) engages the physical connection between the ER and the mitochondrial outer membrane and plays a role in regulating IP{sub 3} receptor-mediated Ca{sup 2+} influx and the phospholipid transport between the two organelles. The MAM contains certain signaling and membrane-tethering proteins but also lipids including cholesterol. The biophysical role of lipids at the MAM, specifically in the physical interaction between the MAM of the ER and mitochondria, remains not totally clarified. Here we employed the in vitro membrane association assay to investigate the role of cholesterol in the association between MAMs and mitochondria. The purified MAMs and mitochondria were mixed in vitro in a test tube and then the physical association of the two subcellular organelles was quantified indirectly by measuring the presence of the MAM-specific protein sigma-1 receptors in the mitochondria fraction. Purified MAMs contained free cholesterol approximately 7 times higher than that in microsomes. We found that depletion of cholesterol in MAMs with methyl-{beta}-cyclodextrin (M{beta}C) significantly increases the association between MAMs and mitochondria, whereas M{beta}C saturated with cholesterol does not change the association. {sup 14}C-Serine pulse-labeling demonstrated that the treatment of living cells with M{beta}C decreases the level of de novo synthesized {sup 14}C-phosphatidylserine (PtSer) and concomitantly increases greatly the synthesis of

  20. Ezetimibe Promotes Brush Border Membrane-to-Lumen Cholesterol Efflux in the Small Intestine.

    Directory of Open Access Journals (Sweden)

    Takanari Nakano

    Full Text Available Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1, an apical membrane cholesterol transporter of enterocytes, thereby reduces intestinal cholesterol absorption. This treatment also increases extrahepatic reverse cholesterol transport via an undefined mechanism. To explore this, we employed a trans-intestinal cholesterol efflux (TICE assay, which directly detects circulation-to-intestinal lumen 3H-cholesterol transit in a cannulated jejunal segment, and found an increase of TICE by 45%. To examine whether such increase in efflux occurs at the intestinal brush border membrane(BBM-level, we performed luminal perfusion assays, similar to TICE but the jejunal wall was labelled with orally-given 3H-cholesterol, and determined elevated BBM-to-lumen cholesterol efflux by 3.5-fold with ezetimibe. Such increased efflux probably promotes circulation-to-lumen cholesterol transit eventually; thus increases TICE. Next, we wondered how inhibition of NPC1L1, an influx transporter, resulted in increased efflux. When we traced orally-given 3H-cholesterol in mice, we found that lumen-to-BBM 3H-cholesterol transit was rapid and less sensitive to ezetimibe treatment. Comparison of the efflux and fractional cholesterol absorption revealed an inverse correlation, indicating the efflux as an opposite-regulatory factor for cholesterol absorption efficiency and counteracting to the naturally-occurring rapid cholesterol influx to the BBM. These suggest that the ezetimibe-stimulated increased efflux is crucial in reducing cholesterol absorption. Ezetimibe-induced increase in cholesterol efflux was approximately 2.5-fold greater in mice having endogenous ATP-binding cassette G5/G8 heterodimer, the major sterol efflux transporter of enterocytes, than the knockout counterparts, suggesting that the heterodimer confers additional rapid BBM-to-lumen cholesterol efflux in response to NPC1L1 inhibition. The observed framework for intestinal cholesterol fluxes may provide ways to

  1. Cloning and expression of a novel lysophospholipase which structurally resembles lecithin cholesterol acyltransferase.

    Science.gov (United States)

    Taniyama, Y; Shibata, S; Kita, S; Horikoshi, K; Fuse, H; Shirafuji, H; Sumino, Y; Fujino, M

    1999-04-02

    Lecithin cholesterol acyltransferase (LCAT) is the key enzyme in the esterification of plasma cholesterol and in the reverse cholesterol transport on high-density lipoprotein (HDL). We have found a novel LCAT-related gene among differentially expressed cDNA fragments between two types of foam cells derived from THP-1 cells, which are different in cholesterol efflux ability, using a subtractive PCR technique. The deduced 412-amino-acid sequence has 49% amino acid sequence similarity with human LCAT. In contrast to the liver-specific expression of LCAT, mRNA expression of the gene was observed mainly in peripheral tissues including kidney, placenta, pancreas, testis, spleen, heart, and skeletal muscle. The protein exists in human plasma and is probably associated with HDL. Moreover, we discovered that the recombinant protein hydrolyzed lysophosphatidylcholine (lysoPC), a proatherogenic lipid, to glycerophosphorylcholine and a free fatty acid. We have therefore named this novel enzyme LCAT-like lysophospholipase (LLPL), through which a new catabolic pathway for lysoPC on lipoproteins could be elucidated. Copyright 1999 Academic Press.

  2. RECOVERY ACT - Thylakoid Assembly and Folded Protein Transport by the Tat Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Dabney-Smith, Carole [Miami Univ., Oxford, OH (United States)

    2016-07-18

    Assembly of functional photosystems complete with necessary intrinsic (membrane-bound) and extrinsic proteins requires the function of at least 3 protein transport pathways in thylakoid membranes. Our research focuses on one of those pathways, a unique and essential protein transport pathway found in the chloroplasts of plants, bacteria, and some archaebacteria, the Twin arginine translocation (Tat) system. The chloroplast Tat (cpTat) system is thought to be responsible for the proper location of ~50% of thylakoid lumen proteins, several of which are necessary for proper photosystem assembly, maintenance, and function. Specifically, cpTat systems are unique because they transport fully folded and assembled proteins across ion tight membranes using only three membrane components, Tha4, Hcf106, and cpTatC, and the protonmotive force generated by photosynthesis. Despite the importance of the cpTat system in plants, the mechanism of transport of a folded precursor is not well known. Our long-term goal is to investigate the role protein transport systems have on organelle biogenesis, particularly the assembly of membrane protein complexes in thylakoids of chloroplasts. The objective of this proposal is to correlate structural changes in the membrane-bound cpTat component, Tha4, to the mechanism of translocation of folded-precursor substrates across the membrane bilayer by using a cysteine accessibility and crosslinking approach. Our central hypothesis is that the precursor passes through a proteinaceous pore of assembled Tha4 protomers that have undergone a conformational or topological change in response to transport. This research is predicated upon the observations that Tha4 exists in molar excess in the membrane relative to the other cpTat components; its regulated assembly to the precursor-bound receptor; and our data showing oligomerization of Tha4 into very large complexes in response to transport. Our rationale for these studies is that understanding cp

  3. Cysteine-rich intestinal protein binds zinc during transmucosal zinc transport

    International Nuclear Information System (INIS)

    Hempe, J.M.; Cousins, R.J.

    1991-01-01

    The mechanism of zinc absorption has not been delineated, but kinetic studies show that both passive and carrier-mediated processes are involved. The authors have identified a low molecular mass zinc-binding protein in the soluble fraction of rat intestinal mucosa that could function as an intracellular zinc carrier. The protein was not detected in liver or pancreas, suggesting a role specific to the intestine. The protein binds zinc during transmucosal zinc transport and shows signs of saturation at higher luminal zinc concentrations, characteristics consistent with a role in carrier-mediated zinc absorption. Microsequence analysis of the protein purified by gel-filtration HPCL and SDS/PAGE showed complete identity within the first 41 N-terminal amino acids with the deduced protein sequence of cysteine-rich intestinal protein. These investigators showed that the gene for this protein is developmentally regulated in neonates during the suckling period, conserved in many vertebrate species, and predominantly expressed in the small intestine. Cysteine-rich intestinal protein contains a recently identified conserved sequence of histidine and cysteine residues, the LIM motif, which our results suggest confers metal-binding properties that are important for zinc transport and/or functions of this micronutrient

  4. Cholesterol impairment contributes to neuroserpin aggregation

    Science.gov (United States)

    Giampietro, Costanza; Lionetti, Maria Chiara; Costantini, Giulio; Mutti, Federico; Zapperi, Stefano; La Porta, Caterina A. M.

    2017-03-01

    Intraneural accumulation of misfolded proteins is a common feature of several neurodegenerative pathologies including Alzheimer’s and Parkinson’s diseases, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB). FENIB is a rare disease due to a point mutation in neuroserpin which accelerates protein aggregation in the endoplasmic reticulum (ER). Here we show that cholesterol depletion induced either by prolonged exposure to statins or by inhibiting the sterol reg-ulatory binding-element protein (SREBP) pathway also enhances aggregation of neuroserpin proteins. These findings can be explained considering a computational model of protein aggregation under non-equilibrium conditions, where a decrease in the rate of protein clearance improves aggregation. Decreasing cholesterol in cell membranes affects their biophysical properties, including their ability to form the vesicles needed for protein clearance, as we illustrate by a simple mathematical model. Taken together, these results suggest that cholesterol reduction induces neuroserpin aggregation, even in absence of specific neuroserpin mutations. The new mechanism we uncover could be relevant also for other neurodegenerative diseases associated with protein aggregation.

  5. Electronic transport on the spatial structure of the protein: Three-dimensional lattice model

    International Nuclear Information System (INIS)

    Sarmento, R.G.; Frazão, N.F.; Macedo-Filho, A.

    2017-01-01

    Highlights: • The electronic transport on the structure of the three-dimensional lattice model of the protein is studied. • The signing of the current–voltage is directly affected by permutations of the weak bonds in the structure. • Semiconductor behave of the proteins suggest a potential application in the development of novel biosensors. - Abstract: We report a numerical analysis of the electronic transport in protein chain consisting of thirty-six standard amino acids. The protein chains studied have three-dimensional structure, which can present itself in three distinct conformations and the difference consist in the presence or absence of thirteen hydrogen-bondings. Our theoretical method uses an electronic tight-binding Hamiltonian model, appropriate to describe the protein segments modeled by the amino acid chain. We note that the presence and the permutations between weak bonds in the structure of proteins are directly related to the signing of the current–voltage. Furthermore, the electronic transport depends on the effect of temperature. In addition, we have found a semiconductor behave in the models investigated and it suggest a potential application in the development of novel biosensors for molecular diagnostics.

  6. Electronic transport on the spatial structure of the protein: Three-dimensional lattice model

    Energy Technology Data Exchange (ETDEWEB)

    Sarmento, R.G. [Departamento de Ciências Biológicas, Universidade Federal do Piauí, 64800-000 Floriano, PI (Brazil); Frazão, N.F. [Centro de Educação e Saúde, Universidade Federal de Campina Grande, 581750-000 Cuité, PB (Brazil); Macedo-Filho, A., E-mail: amfilho@gmail.com [Campus Prof. Antonio Geovanne Alves de Sousa, Universidade Estadual do Piauí, 64260-000 Piripiri, PI (Brazil)

    2017-01-30

    Highlights: • The electronic transport on the structure of the three-dimensional lattice model of the protein is studied. • The signing of the current–voltage is directly affected by permutations of the weak bonds in the structure. • Semiconductor behave of the proteins suggest a potential application in the development of novel biosensors. - Abstract: We report a numerical analysis of the electronic transport in protein chain consisting of thirty-six standard amino acids. The protein chains studied have three-dimensional structure, which can present itself in three distinct conformations and the difference consist in the presence or absence of thirteen hydrogen-bondings. Our theoretical method uses an electronic tight-binding Hamiltonian model, appropriate to describe the protein segments modeled by the amino acid chain. We note that the presence and the permutations between weak bonds in the structure of proteins are directly related to the signing of the current–voltage. Furthermore, the electronic transport depends on the effect of temperature. In addition, we have found a semiconductor behave in the models investigated and it suggest a potential application in the development of novel biosensors for molecular diagnostics.

  7. Prion Protein Regulates Iron Transport by Functioning as a Ferrireductase

    Science.gov (United States)

    Singh, Ajay; Haldar, Swati; Horback, Katharine; Tom, Cynthia; Zhou, Lan; Meyerson, Howard; Singh, Neena

    2017-01-01

    Prion protein (PrPC) is implicated in the pathogenesis of prion disorders, but its normal function is unclear. We demonstrate that PrPC is a ferrireductase (FR), and its absence causes systemic iron deficiency in PrP knock-out mice (PrP−/−). When exposed to non-transferrin-bound (NTB) radioactive-iron (59FeCl3) by gastric-gavage, PrP−/− mice absorb significantly more 59Fe from the intestinal lumen relative to controls, indicating appropriate systemic response to the iron deficiency. Chronic exposure to excess dietary iron corrects this deficiency, but unlike wild-type (PrP+/+) controls that remain iron over-loaded, PrP−/− mice revert back to the iron deficient phenotype after 5 months of chase on normal diet. Bone marrow (BM) preparations of PrP−/− mice on normal diet show relatively less stainable iron, and this phenotype is only partially corrected by intraperitoneal administration of excess iron-dextran. Cultured PrP−/− BM-macrophages incorporate significantly less NTB-59Fe in the absence or presence of excess extracellular iron, indicating reduced uptake and/or storage of available iron in the absence of PrPC. When expressed in neuroblastoma cells, PrPC exhibits NAD(P)H-dependent cell-surface and intracellular FR activity that requires the copper-binding octa-peptide-repeat region and linkage to the plasma membrane for optimal function. Incorporation of NTB-59Fe by neuroblastoma cells correlates with FR activity of PrPC, implicating PrPC in cellular iron uptake and metabolism. These observations explain the correlation between PrPC expression and cellular iron levels, and the cause of iron imbalance in sporadic-Creutzfeldt-Jakob-disease brains where PrPC accumulates as insoluble aggregates. PMID:23478311

  8. Regorafenib is transported by the organic anion transporter 1B1 and the multidrug resistance protein 2.

    Science.gov (United States)

    Ohya, Hiroki; Shibayama, Yoshihiko; Ogura, Jiro; Narumi, Katsuya; Kobayashi, Masaki; Iseki, Ken

    2015-01-01

    Regorafenib is a small molecule inhibitor of tyrosine kinases, and has been shown to improve the outcomes of patients with advanced colorectal cancer and advanced gastrointestinal stromal tumors. The transport profiles of regorafenib by various transporters were evaluated. HEK293/organic anion transporting polypeptide 1B1 (OATP1B1) cells exhibited increased drug sensitivity to regorafenib. Regorafenib inhibited the uptake of 3H-estrone sulfate by HEK293/OATP1B1 cells in a dose-dependent manner, but did not affect its elimination by P-glycoproteins. The concentration of regorafenib was significantly lower in LLC-PK1/multidrug resistance protein 2 (MRP2) cells than in LLC-PK1 cells treated with the MRP2 inhibitor, MK571. MK571 abolished the inhibitory effects of regorafenib on intracellular accumulation in LLC-PK1/MRP2 cells. The uptake of regorafenib was significantly higher in HEK293/OATP1B1 cells than in OATP1B1-mock cells. Transport kinetics values were estimated to be Km=15.9 µM and Vmax=1.24 nmol/mg/min. No significant difference was observed in regorafenib concentrations between HEK293/OATP1B3 and OATP1B3-mock cells. These results indicated that regorafenib is a substrate for MRP2 and OATP1B1, and also suggest that the substrate preference of regorafenib may implicate the pharmacokinetic profiles of regorafenib.

  9. Annexins as organizers of cholesterol- and sphingomyelin-enriched membrane microdomains in Niemann-Pick type C disease.

    Science.gov (United States)

    Domon, Magdalena; Nasir, Mehmet Nail; Matar, Gladys; Pikula, Slawomir; Besson, Françoise; Bandorowicz-Pikula, Joanna

    2012-06-01

    Growing evidence suggests that membrane microdomains enriched in cholesterol and sphingomyelin are sites for numerous cellular processes, including signaling, vesicular transport, interaction with pathogens, and viral infection, etc. Recently some members of the annexin family of conserved calcium and membrane-binding proteins have been recognized as cholesterol-interacting molecules and suggested to play a role in the formation, stabilization, and dynamics of membrane microdomains to affect membrane lateral organization and to attract other proteins and signaling molecules onto their territory. Furthermore, annexins were implicated in the interactions between cytosolic and membrane molecules, in the turnover and storage of cholesterol and in various signaling pathways. In this review, we focus on the mechanisms of interaction of annexins with lipid microdomains and the role of annexins in membrane microdomains dynamics including possible participation of the domain-associated forms of annexins in the etiology of human lysosomal storage disease called Niemann-Pick type C disease, related to the abnormal storage of cholesterol in the lysosome-like intracellular compartment. The involvement of annexins and cholesterol/sphingomyelin-enriched membrane microdomains in other pathologies including cardiac dysfunctions, neurodegenerative diseases, obesity, diabetes mellitus, and cancer is likely, but is not supported by substantial experimental observations, and therefore awaits further clarification.

  10. Disparate effects of p24alpha and p24delta on secretory protein transport and processing.

    Directory of Open Access Journals (Sweden)

    Jeroen R P M Strating

    Full Text Available BACKGROUND: The p24 family is thought to be somehow involved in endoplasmic reticulum (ER-to-Golgi protein transport. A subset of the p24 proteins (p24alpha(3, -beta(1, -gamma(3 and -delta(2 is upregulated when Xenopus laevis intermediate pituitary melanotrope cells are physiologically activated to produce vast amounts of their major secretory cargo, the prohormone proopiomelanocortin (POMC. METHODOLOGY/PRINCIPAL FINDINGS: Here we find that transgene expression of p24alpha(3 or p24delta(2 specifically in the Xenopus melanotrope cells in both cases causes an effective displacement of the endogenous p24 proteins, resulting in severely distorted p24 systems and disparate melanotrope cell phenotypes. Transgene expression of p24alpha(3 greatly reduces POMC transport and leads to accumulation of the prohormone in large, ER-localized electron-dense structures, whereas p24delta(2-transgenesis does not influence the overall ultrastructure of the cells nor POMC transport and cleavage, but affects the Golgi-based processes of POMC glycomaturation and sulfation. CONCLUSIONS/SIGNIFICANCE: Transgenic expression of two distinct p24 family members has disparate effects on secretory pathway functioning, illustrating the specificity and non-redundancy of our transgenic approach. We conclude that members of the p24 family furnish subcompartments of the secretory pathway with specific sets of machinery cargo to provide the proper microenvironments for efficient and correct secretory protein transport and processing.

  11. Steric exclusion and protein conformation determine the localization of plasma membrane transporters

    NARCIS (Netherlands)

    Bianchi, Frans; Syga, Łukasz; Moiset, Gemma; Spakman, Dian; Schavemaker, Paul E; Punter, Christiaan M; Seinen, Anne-Bart; van Oijen, Antoine M; Robinson, Andrew; Poolman, Bert

    2018-01-01

    The plasma membrane (PM) of Saccharomyces cerevisiae contains membrane compartments, MCC/eisosomes and MCPs, named after the protein residents Can1 and Pma1, respectively. Using high-resolution fluorescence microscopy techniques we show that Can1 and the homologous transporter Lyp1 are able to

  12. Acid-base status determines the renal expression of Ca2+ and Mg2+ transport proteins.

    NARCIS (Netherlands)

    Nijenhuis, T.; Renkema, K.Y.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2006-01-01

    Chronic metabolic acidosis results in renal Ca2+ and Mg2+ wasting, whereas chronic metabolic alkalosis is known to exert the reverse effects. It was hypothesized that these adaptations are mediated at least in part by the renal Ca2+ and Mg2+ transport proteins. The aim of this study, therefore, was

  13. Crystallization of the A-Domain of the Mannitol Transport Protein Enzyme IImtl

    NARCIS (Netherlands)

    Lammers, Leidy A.; Dijkstra, Bauke W.; Weeghel, Rob P. van; Pas, Hendri H.; Robillard, George T.

    1992-01-01

    The A-domain of the mannitol transport protein enzyme IImtl from Escherichia coli (relative molecular mass 16,300) was crystallized, both at room temperature and 4°C, from 40% polyethylene glycol 6000 (pH 8.5 to 9.0) using the hanging-drop method of vapour diffusion. The crystals have the monoclinic

  14. Lipid Raft-Based Membrane Compartmentation of a Plant Transport Protein Expressed in Saccharomyces cerevisiae

    Czech Academy of Sciences Publication Activity Database

    Grossmann, Q.; Opekarová, Miroslava; Nováková, L.; Stolz, J.; Tanner, W.

    2006-01-01

    Roč. 5, č. 6 (2006), s. 945-953 ISSN 1535-9778 R&D Projects: GA MŠk LC545 Institutional research plan: CEZ:AV0Z50200510 Keywords : saccharomyces cerevisiae * plant transport protein * hup1 Subject RIV: EE - Microbiology, Virology Impact factor: 3.707, year: 2006

  15. The peritoneal transport of serum proteins and neutral dextran in CAPD patients

    NARCIS (Netherlands)

    Krediet, R. T.; Koomen, G. C.; Koopman, M. G.; Hoek, F. J.; Struijk, D. G.; Boeschoten, E. W.; Arisz, L.

    1989-01-01

    The peritoneal transport of five serum proteins and intravenously-administered neutral dextran was studied in 13 CAPD patients. In all patients a study was done three hours after the administration of dextran. In nine the study was repeated after 14 hours, and in six also after 38 hours. Using gel

  16. Data in support of a central role of plasminogen activator inhibitor-2 polymorphism in recurrent cardiovascular disease risk in the setting of high HDL cholesterol and C-reactive protein using Bayesian network modeling

    Directory of Open Access Journals (Sweden)

    James P. Corsetti

    2016-09-01

    Full Text Available Data is presented that was utilized as the basis for Bayesian network modeling of influence pathways focusing on the central role of a polymorphism of plasminogen activator inhibitor-2 (PAI-2 on recurrent cardiovascular disease risk in patients with high levels of HDL cholesterol and C-reactive protein (CRP as a marker of inflammation, “Influences on Plasminogen Activator Inhibitor-2 Polymorphism-Associated Recurrent Cardiovascular Disease Risk in Patients with High HDL Cholesterol and Inflammation” (Corsetti et al., 2016; [1]. The data consist of occurrence of recurrent coronary events in 166 post myocardial infarction patients along with 1. clinical data on gender, race, age, and body mass index; 2. blood level data on 17 biomarkers; and 3. genotype data on 53 presumptive CVD-related single nucleotide polymorphisms. Additionally, a flow diagram of the Bayesian modeling procedure is presented along with Bayesian network subgraphs (root nodes to outcome events utilized as the data from which PAI-2 associated influence pathways were derived (Corsetti et al., 2016; [1]. Keywords: Recurrent cardiovascular disease risk, Pathophysiology, Plasminogen activator inhibitor-2, Bayesian network

  17. Cardiometabolic risk factors as apolipoprotein B, triglyceride/HDL-cholesterol ratio and C-reactive protein, in adolescents with and without obesity: cross-sectional study in middle class suburban children.

    Science.gov (United States)

    Musso, Carla; Graffigna, Mabel; Soutelo, Jimena; Honfi, Margarita; Ledesma, Laura; Miksztowicz, Verónica; Pazos, Mónica; Migliano, Marta; Schreier, Laura Ester; Berg, Gabriela Alicia

    2011-05-01

    The prevalence of obesity (OB), overweight (OW), and metabolic syndrome (MS) has increased worldwide. That imposes a substantial risk for type 2 diabetes and premature cardiovascular disease. However, to date no unified criteria exist to asses risk or outcomes in children and adolescents. To establish the presence of OB/OW and MS and risk factors for cardiovascular disease in adolescents. Male (n = 514) and female (n = 429) adolescents from high school were studied (11-14 yr). Weight, height, body mass index (BMI), waist circumference (WC), and blood pressure were determined in all subjects. Glucose, lipoprotein profile, apolipoprotein B (apoB), and high-sensitivity C-reactive protein (hs-CRP) levels were measured. Triglyceride/high-density lipoprotein-cholesterol (TG/HDL-cholesterol) ratio was calculated. The frequency of OB/OW and MS were 22.2 and 3.7%, respectively. In comparison to healthy adolescents, TG/HDL-cholesterol ratio was increased in OB/OW (2.9 ± 2.5 vs. 1.6 ± 1.0) and MS groups (4.0 ± 2.5 vs. 1.6 ± 0.9), p < 0.001. OB/OW adolescents presented higher values of hs-CRP in comparison to non-obese, median (range): 1.9 (0.1-9.4) vs. 1.4 (0.1-9.9), mg/L, p < 0.001. ApoB (mean ± SD) was 71 ± 21 mg/dL in MS group and 59 ± 17 mg/dL in those without MS (p < 0.001). TG/HDL-cholesterol ratio positively correlated with BMI (r = 0.18, p < 0.001), WC (r = 0.24, p < 0.001), and apoB (r = 0.24, p < 0.001); hs-CRP correlated with WC (r = 0.14, p < 0.001) and BMI (r = 0.17, p < 0.001). Even when the frequency of OB, OW, and MS in adolescents was low, those subjects presented an atherogenic lipoprotein. These findings emphasize the importance to evaluate cardiovascular risk factors in adolescents to assess strategies to prevent future disease. © 2011 John Wiley & Sons A/S.

  18. Structural and functional studies of conserved nucleotide-binding protein LptB in lipopolysaccharide transport

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhongshan [Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, NR4 7TJ (United Kingdom); College of Life Sciences, Sichuan University, Chengdu 610065 (China); Biomedical Sciences Research Complex, School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST (United Kingdom); Xiang, Quanju [College of Life Sciences, Sichuan University, Chengdu 610065 (China); Biomedical Sciences Research Complex, School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST (United Kingdom); Department of Microbiology, College of Resource and Environment Science, Sichuan Agriculture University, Yaan 625000 (China); Zhu, Xiaofeng [College of Life Sciences, Sichuan University, Chengdu 610065 (China); Dong, Haohao [Biomedical Sciences Research Complex, School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST (United Kingdom); He, Chuan [School of Electronics and Information, Wuhan Technical College of Communications, No. 6 Huangjiahu West Road, Hongshan District, Wuhan, Hubei 430065 (China); Wang, Haiyan; Zhang, Yizheng [College of Life Sciences, Sichuan University, Chengdu 610065 (China); Wang, Wenjian, E-mail: Wenjian166@gmail.com [Laboratory of Department of Surgery, The First Affiliated Hospital, Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, Guangdong 510080 (China); Dong, Changjiang, E-mail: C.Dong@uea.ac.uk [Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, NR4 7TJ (United Kingdom)

    2014-09-26

    Highlights: • Determination of the structure of the wild-type LptB in complex with ATP and Mg{sup 2+}. • Demonstrated that ATP binding residues are essential for LptB’s ATPase activity and LPS transport. • Dimerization is required for the LptB’s function and LPS transport. • Revealed relationship between activity of the LptB and the vitality of E. coli cells. - Abstract: Lipopolysaccharide (LPS) is the main component of the outer membrane of Gram-negative bacteria, which plays an essential role in protecting the bacteria from harsh conditions and antibiotics. LPS molecules are transported from the inner membrane to the outer membrane by seven LPS transport proteins. LptB is vital in hydrolyzing ATP to provide energy for LPS transport, however this mechanism is not very clear. Here we report wild-type LptB crystal structure in complex with ATP and Mg{sup 2+}, which reveals that its structure is conserved with other nucleotide-binding proteins (NBD). Structural, functional and electron microscopic studies demonstrated that the ATP binding residues, including K42 and T43, are crucial for LptB’s ATPase activity, LPS transport and the vitality of Escherichia coli cells with the exceptions of H195A and Q85A; the H195A mutation does not lower its ATPase activity but impairs LPS transport, and Q85A does not alter ATPase activity but causes cell death. Our data also suggest that two protomers of LptB have to work together for ATP hydrolysis and LPS transport. These results have significant impacts in understanding the LPS transport mechanism and developing new antibiotics.

  19. Structural and functional studies of conserved nucleotide-binding protein LptB in lipopolysaccharide transport

    International Nuclear Information System (INIS)

    Wang, Zhongshan; Xiang, Quanju; Zhu, Xiaofeng; Dong, Haohao; He, Chuan; Wang, Haiyan; Zhang, Yizheng; Wang, Wenjian; Dong, Changjiang

    2014-01-01

    Highlights: • Determination of the structure of the wild-type LptB in complex with ATP and Mg 2+ . • Demonstrated that ATP binding residues are essential for LptB’s ATPase activity and LPS transport. • Dimerization is required for the LptB’s function and LPS transport. • Revealed relationship between activity of the LptB and the vitality of E. coli cells. - Abstract: Lipopolysaccharide (LPS) is the main component of the outer membrane of Gram-negative bacteria, which plays an essential role in protecting the bacteria from harsh conditions and antibiotics. LPS molecules are transported from the inner membrane to the outer membrane by seven LPS transport proteins. LptB is vital in hydrolyzing ATP to provide energy for LPS transport, however this mechanism is not very clear. Here we report wild-type LptB crystal structure in complex with ATP and Mg 2+ , which reveals that its structure is conserved with other nucleotide-binding proteins (NBD). Structural, functional and electron microscopic studies demonstrated that the ATP binding residues, including K42 and T43, are crucial for LptB’s ATPase activity, LPS transport and the vitality of Escherichia coli cells with the exceptions of H195A and Q85A; the H195A mutation does not lower its ATPase activity but impairs LPS transport, and Q85A does not alter ATPase activity but causes cell death. Our data also suggest that two protomers of LptB have to work together for ATP hydrolysis and LPS transport. These results have significant impacts in understanding the LPS transport mechanism and developing new antibiotics

  20. Prediction of arsenic and antimony transporter major intrinsic proteins from the genomes of crop plants.

    Science.gov (United States)

    Azad, Abul Kalam; Ahmed, Jahed; Alum, Md Asraful; Hasan, Md Mahbub; Ishikawa, Takahiro; Sawa, Yoshihiro

    2018-02-01

    Major intrinsic proteins (MIPs), commonly known as aquaporins, transport water and non-polar small solutes. Comparing the 3D models and the primary selectivity-related motifs (two Asn-Pro-Ala (NPA) regions, the aromatic/arginine (ar/R) selectivity filter, and Froger's positions (FPs)) of all plant MIPs that have been experimentally proven to transport arsenic (As) and antimony (Sb), some substrate-specific signature sequences (SSSS) or specificity determining sites (SDPs) have been predicted. These SSSS or SDPs were determined in 543 MIPs found in the genomes of 12 crop plants; the As and Sb transporters were predicted to be distributed in noduline-26 like intrinsic proteins (NIPs), and every plant had one or several As and Sb transporter NIPs. Phylogenetic grouping of the NIP subfamily based on the ar/R selectivity filter and FPs were linked to As and Sb transport. We further determined the group-wise substrate selectivity profiles of the NIPs in the 12 crop plants. In addition to two NPA regions, the ar/R filter, and FPs, certain amino acids especially in the pore line, loop D, and termini contribute to the functional distinctiveness of the NIP groups. Expression analysis of transcripts in different organs indicated that most of the As and Sb transporter NIPs were expressed in roots. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Atorvastatin increases HDL cholesterol by reducing CETP expression in cholesterol-fed APOE*3-Leiden.CETP mice

    NARCIS (Netherlands)

    Haan, W. de; Hoogt, C.C. van der; Westerterp, M.; Hoekstra, M.; Dallinga-Thie, G.M.; Princen, H.M.G.; Romijn, J.A.; Jukema, J.W.; Havekes, L.M.; Rensen, P.C.N.

    2008-01-01

    Objective: In addition to lowering low-density lipoprotein (LDL)-cholesterol, statins modestly increase high-density lipoprotein (HDL)-cholesterol in humans and decrease cholesteryl ester transfer protein (CETP) mass and activity. Our aim was to determine whether the increase in HDL depends on CETP

  2. Tubule urate and PAH transport: sensitivity and specificity of serum protein inhibition

    International Nuclear Information System (INIS)

    Grantham, J.J.; Kennedy, J.; Cowley, B.

    1987-01-01

    Macromolecules in rabbit serum inhibit the cellular uptake and transepithelial secretion of [ 14 C]urate and p-[ 3 H]aminohippurate ([ 3 H]PAH) in rabbit S 2 proximal tubule segments. To understand better the potential role these inhibitors may have in the regulation of renal organic anion excretion, the authors examined the specificity and relative inhibitory effects on tubule urate and PAH transport of albumin and γ-globulin, the major inhibitory proteins in rabbit serum. Native rabbit serum markedly inhibited the cellular accumulation or urate and PAH by isolated nonperfused segments. Urate and PAH transport was also inhibited by bovine serum, human serum, Cohn-fractionated rabbit albumin, and rabbit γ-globulin, but not by Cohn-fractionated bovine serum albumin. α-Lactalbumin and β-lactoglobulin, derived from milk, also inhibited urate and PAH transport, but to a lesser extent than albumin and γ-globulin. The transport inhibitory effects of proteins were independent of their binding to urate and PAH. Unidirectional influx and the steady-state intracellular accumulation of urate and PAH in suspensions of proximal tubules were decreased by rabbit serum proteins, suggesting that these inhibitors act on the external face of the cells to diminish the uptake of the organic anions. These studies indicate that the principal plasma proteins (albumin and γ-globulin) significantly inhibit urate and PAH transporters in the basolateral membranes of S 2 proximal tubules. They suggest that circulating plasma proteins that can penetrate the basement membrane of proximal tubules may directly modulate the renal excretion of urate and PAH

  3. Cholesterol trafficking and raft-like membrane domain composition mediate scavenger receptor class B type 1-dependent lipid sensing in intestinal epithelial cells.

    Science.gov (United States)

    Morel, Etienne; Ghezzal, Sara; Lucchi, Géraldine; Truntzer, Caroline; Pais de Barros, Jean-Paul; Simon-Plas, Françoise; Demignot, Sylvie; Mineo, Chieko; Shaul, Philip W; Leturque, Armelle; Rousset, Monique; Carrière, Véronique

    2018-02-01

    Scavenger receptor Class B type 1 (SR-B1) is a lipid transporter and sensor. In intestinal epithelial cells, SR-B1-dependent lipid sensing is associated with SR-B1 recruitment in raft-like/ detergent-resistant membrane domains and interaction of its C-terminal transmembrane domain with plasma membrane cholesterol. To clarify the initiating events occurring during lipid sensing by SR-B1, we analyzed cholesterol trafficking and raft-like domain composition in intestinal epithelial cells expressing wild-type SR-B1 or the mutated form SR-B1-Q445A, defective in membrane cholesterol binding and signal initiation. These features of SR-B1 were found to influence both apical cholesterol efflux and intracellular cholesterol trafficking from plasma membrane to lipid droplets, and the lipid composition of raft-like domains. Lipidomic analysis revealed likely participation of d18:0/16:0 sphingomyelin and 16:0/0:0 lysophosphatidylethanolamine in lipid sensing by SR-B1. Proteomic analysis identified proteins, whose abundance changed in raft-like domains during lipid sensing, and these included molecules linked to lipid raft dynamics and signal transduction. These findings provide new insights into the role of SR-B1 in cellular cholesterol homeostasis and suggest molecular links between SR-B1-dependent lipid sensing and cell cholesterol and lipid droplet dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Pitfalls in the detection of cholesterol in Huntington's disease models.

    Science.gov (United States)

    Marullo, Manuela; Valenza, Marta; Leoni, Valerio; Caccia, Claudio; Scarlatti, Chiara; De Mario, Agnese; Zuccato, Chiara; Di Donato, Stefano; Carafoli, Ernesto; Cattaneo, Elena

    2012-10-11

    Background Abnormalities in brain cholesterol homeostasis have been reported in Huntington's disease (HD), an adult-onset neurodegenerative disorder caused by an expansion in the number of CAG repeats in the huntingtin (HTT) gene. However, the results have been contradictory with respect to whether cholesterol levels increase or decrease in HD models. Biochemical and mass spectrometry methods show reduced levels of cholesterol precursors and cholesterol in HD cells and in the brains of several HD animal models. Abnormal brain cholesterol homeostasis was also inferred from studies in HD patients. In contrast, colorimetric and enzymatic methods indicate cholesterol accumulation in HD cells and tissues. Here we used several methods to investigate cholesterol levels in cultured cells in the presence or absence of mutant HTT protein. Results Colorimetric and enzymatic methods with low sensitivity gave variable results, whereas results from a sensitive analytical method, gas chromatography-mass spectrometry, were more reliable. Sample preparation, high cell density and cell clonality also influenced the detection of intracellular cholesterol. Conclusions Detection of cholesterol in HD samples by colorimetric and enzymatic assays should be supplemented by detection using more sensitive analytical methods. Care must be taken to prepare the sample appropriately. By evaluating lathosterol levels using isotopic dilution mass spectrometry, we confirmed reduced cholesterol biosynthesis in knock-in cells expressing the polyQ mutation in a constitutive or inducible manner. *Correspondence should be addressed to Elena Cattaneo: elena.cattaneo@unimi.it.

  5. Cholesterol and myelin biogenesis.

    Science.gov (United States)

    Saher, Gesine; Simons, Mikael

    2010-01-01

    Myelin consists of several layers of tightly compacted membranes wrapped around axons in the nervous system. The main function of myelin is to provide electrical insulation around the axon to ensure the rapid propagation of nerve conduction. As the myelinating glia terminally differentiates, they begin to produce myelin membranes on a remarkable scale. This membrane is unique in its composition being highly enriched in lipids, in particular galactosylceramide and cholesterol. In this review we will summarize the role of cholesterol in myelin biogenesis in the central and peripheral nervous system.

  6. A novel cholesterol-producing Pichia pastoris strain is an ideal host for functional expression of human Na,K-ATPase α3β1 isoform.

    Science.gov (United States)

    Hirz, Melanie; Richter, Gerald; Leitner, Erich; Wriessnegger, Tamara; Pichler, Harald

    2013-11-01

    The heterologous expression of mammalian membrane proteins in lower eukaryotes is often hampered by aberrant protein localization, structure, and function, leading to enhanced degradation and, thus, low expression levels. Substantial quantities of functional membrane proteins are necessary to elucidate their structure-function relationships. Na,K-ATPases are integral, human membrane proteins that specifically interact with cholesterol and phospholipids, ensuring protein stability and enhancing ion transport activity. In this study, we present a Pichia pastoris strain which was engineered in its sterol pathway towards the synthesis of cholesterol instead of ergosterol to foster the functional expression of human membrane proteins. Western blot analyses revealed that cholesterol-producing yeast formed enhanced and stable levels of human Na,K-ATPase α3β1 isoform. ATPase activity assays suggested that this Na,K-ATPase isoform was functionally expressed in the plasma membrane. Moreover, [(3)H]-ouabain cell surface-binding studies underscored that the Na,K-ATPase was present in high numbers at the cell surface, surpassing reported expression strains severalfold. This provides evidence that the humanized sterol composition positively influenced Na,K-ATPase α3β1 stability, activity, and localization to the yeast plasma membrane. Prospectively, cholesterol-producing yeast will have high potential for functional expression of many mammalian membrane proteins.

  7. Alzheimer's disease: neuroprogesterone, epoxycholesterol, and ABC transporters as determinants of neurodesmosterol tissue levels and its role in amyloid protein processing.

    Science.gov (United States)

    Javitt, Norman B

    2013-01-01

    Evidence is emerging that during the development of Alzheimer's disease (AD), changes in the synthesis and metabolism of cholesterol and progesterone are occurring that may or may not affect the progression of the disease. The concept arose from the recognition that dehydrocholesterol 24-reductase (DHCR24/Seladin-1), one of the nine enzymes in the endoplasmic reticulum that determines the transformation of lanosterol to cholesterol, is selectively reduced in late AD. As a consequence, the tissue level of desmosterol increases, affecting the expression of ABC transporters and the structure of lipid rafts, both determinants of amyloid-β processing. However, the former effect is considered beneficial and the latter detrimental to processing. Other determinants of desmosterol tissue levels are 24,25 epoxycholesterol and the ABCG1 and ABCG4 transporters. Progesterone and its metabolites are determinants of tissue levels of desmosterol and several other sterol intermediates in cholesterol synthesis. Animal models indicate marked elevations in the tissue levels of these sterols at early time frames in the progression of neurodegenerative diseases. The low level of neuroprogesterone and metabolites in AD are consonant with the low level of desmosterol and may have a role in amyloid-β processing. The sparse data that has accumulated appears to be a sufficient basis for proposing a systematic evaluation of the biologic roles of sterol intermediates in the slowly progressive neurodegeneration characteristic of AD.

  8. Biogenesis of plasma membrane cholesterol

    International Nuclear Information System (INIS)

    Lange, Y.

    1986-01-01

    A striking feature of the molecular organization of eukaryotic cells is the singular enrichment of their plasma membranes in sterols. The authors studies are directed at elucidating the mechanisms underlying this inhomogeneous disposition. Cholesterol oxidase catalyzes the oxidation of plasma membrane cholesterol in intact cells, leaving intracellular cholesterol pools untouched. With this technique, the plasma membrane was shown to contain 95% of the unesterified cholesterol of cultured human fibroblasts. Cholesterol synthesized from [ 3 H] acetate moved to the plasma membrane with a half-time of 1 h at 37 0 C. They used equilibrium gradient centrifugation of homogenates of biosynthetically labeled, cholesterol oxidase treated cells to examine the distribution of newly synthesized sterols among intracellular pools. Surprisingly, lanosterol, a major precursor of cholesterol, and intracellular cholesterol both peaked at much lower buoyant density than did 3-hydroxy-3-methylglutaryl-CoA reductase. This suggests that cholesterol biosynthesis is not taken to completion in the endoplasmic reticulum. The cholesterol in the buoyant fraction eventually moved to the plasma membrane. Digitonin treatment increased the density of the newly synthesized cholesterol fractions, indicating that nascent cholesterol in transit is associated with cholesterol-rich membranes. The authors are testing the hypothesis that the pathway of cholesterol biosynthesis is spatially organized in various intracellular membranes such that the sequence of biosynthetic steps both concentrates the sterol and conveys it to the plasma membrane

  9. DIETARY FISH-OIL POTENTIATES BILE ACID-INDUCED CHOLESTEROL SECRETION INTO BILE IN RATS

    NARCIS (Netherlands)

    SMIT, MJ; VERKADE, HJ; HAVINGA, R; VONK, RJ; SCHERPHOF, GL; TVELD, GI; KUIPERS, F

    Recently we demonstrated that dietary fish oil (FO) causes changes in intrahepatic cholesterol transport and hyper secretion of cholesterol into bile in rats V. Clin. Invest. 88: 943-951, 1991). We have now investigated in more detail the relationship between cholesterol and bile acid secretion in

  10. Impaired renal secretion of substrates for the multidrug resistance protein 2 in mutant transport-deficient (TR-) rats.

    NARCIS (Netherlands)

    Masereeuw, R.; Notenboom, S.; Smeets, P.H.E.; Wouterse, A.C.; Russel, F.G.M.

    2003-01-01

    Previous studies with mutant transport-deficient rats (TR(-)), in which the multidrug resistance protein 2 (Mrp2) is lacking, have emphasized the importance of this transport protein in the biliary excretion of a wide variety of glutathione conjugates, glucuronides, and other organic anions. Mrp2 is

  11. Intracellular and transcellular transport of secretory and membrane proteins in the rat hepatocyte

    International Nuclear Information System (INIS)

    Sztul, E.S.

    1984-01-01

    The intra- and transcellular transport of hepatic secretory and membrane proteins was studied in rats in vivo using [ 3 H]fucose and [ 35 S]cyteine as metabolic precursors. Incorporated radioactivity in plasma, bile, and liver subcellular fractions was measured and the labeled proteins of the Golgi complex, bile and plasma were separated by SDS-PAGE and identified by fluorography. 3 H-radioactivity in Golgi fractions peaked at 10 min post injection (p.i.) and then declined concomitantly with the appearance of labeled glycoproteins in plasma. Maximal secretion of secretory fucoproteins from the Golgi complex occurred between 10 and 20 min p.i. In contrast, the clearance of labeled proteins from Golgi membrane subfractions occurred past 30 min p.i., indicating that membrane proteins leave the Golgi complex at least 10 min later than the bulk of content proteins. A major 80K form of Secretory Component (SC) was identified in the bile by precipitation with an anti IgA antibody. A comparative study of kinetics of transport of 35 S-labeled SC and 35 S-labeled albumin showed that albumin peaked in bile at ∼45 min p.i., whereas the SC peak occurred at 80 min p.i., suggesting that the transit time differs for plasma and membrane proteins which are delivered to the bile canaliculus (BC)

  12. Tungsten transport protein A (WtpA) in Pyrococcus furiosus: the first member of a new class of tungstate and molybdate transporters.

    Science.gov (United States)

    Bevers, Loes E; Hagedoorn, Peter-Leon; Krijger, Gerard C; Hagen, Wilfred R

    2006-09-01

    A novel tungstate and molybdate binding protein has been discovered from the hyperthermophilic archaeon Pyrococcus furiosus. This tungstate transport protein A (WtpA) is part of a new ABC transporter system selective for tungstate and molybdate. WtpA has very low sequence similarity with the earlier-characterized transport proteins ModA for molybdate and TupA for tungstate. Its structural gene is present in the genome of numerous archaea and some bacteria. The identification of this new tungstate and molybdate binding protein clarifies the mechanism of tungstate and molybdate transport in organisms that lack the known uptake systems associated with the ModA and TupA proteins, like many archaea. The periplasmic protein of this ABC transporter, WtpA (PF0080), was cloned and expressed in Escherichia coli. Using isothermal titration calorimetry, WtpA was observed to bind tungstate (dissociation constant [K(D)] of 17 +/- 7 pM) and molybdate (K(D) of 11 +/- 5 nM) with a stoichiometry of 1.0 mol oxoanion per mole of protein. These low K(D) values indicate that WtpA has a higher affinity for tungstate than do ModA and TupA and an affinity for molybdate similar to that of ModA. A displacement titration of molybdate-saturated WtpA with tungstate showed that the tungstate effectively replaced the molybdate in the binding site of the protein.

  13. Influence of multidrug resistance and drug transport proteins on chemotherapy drug metabolism.

    Science.gov (United States)

    Joyce, Helena; McCann, Andrew; Clynes, Martin; Larkin, Annemarie

    2015-05-01

    Chemotherapy involving the use of anticancer drugs remains an important strategy in the overall management of patients with metastatic cancer. Acquisition of multidrug resistance remains a major impediment to successful chemotherapy. Drug transporters in cell membranes and intracellular drug metabolizing enzymes contribute to the resistance phenotype and determine the pharmacokinetics of anticancer drugs in the body. ATP-binding cassette (ABC) transporters mediate the transport of endogenous metabolites and xenobiotics including cytotoxic drugs out of cells. Solute carrier (SLC) transporters mediate the influx of cytotoxic drugs into cells. This review focuses on the substrate interaction of these transporters, on their biology and what role they play together with drug metabolizing enzymes in eliminating therapeutic drugs from cells. The majority of anticancer drugs are substrates for the ABC transporter and SLC transporter families. Together, these proteins have the ability to control the influx and the efflux of structurally unrelated chemotherapeutic drugs, thereby modulating the intracellular drug concentration. These interactions have important clinical implications for chemotherapy because ultimately they determine therapeutic efficacy, disease progression/relapse and the success or failure of patient treatment.

  14. Molecular mechanism of ligand recognition by membrane transport protein, Mhp1

    Science.gov (United States)

    Simmons, Katie J; Jackson, Scott M; Brueckner, Florian; Patching, Simon G; Beckstein, Oliver; Ivanova, Ekaterina; Geng, Tian; Weyand, Simone; Drew, David; Lanigan, Joseph; Sharples, David J; Sansom, Mark SP; Iwata, So; Fishwick, Colin WG; Johnson, A Peter; Cameron, Alexander D; Henderson, Peter JF

    2014-01-01

    The hydantoin transporter Mhp1 is a sodium-coupled secondary active transport protein of the nucleobase-cation-symport family and a member of the widespread 5-helix inverted repeat superfamily of transporters. The structure of Mhp1 was previously solved in three different conformations providing insight into the molecular basis of the alternating access mechanism. Here, we elucidate detailed events of substrate binding, through a combination of crystallography, molecular dynamics, site-directed mutagenesis, biochemical/biophysical assays, and the design and synthesis of novel ligands. We show precisely where 5-substituted hydantoin substrates bind in an extended configuration at the interface of the bundle and hash domains. They are recognised through hydrogen bonds to the hydantoin moiety and the complementarity of the 5-substituent for a hydrophobic pocket in the protein. Furthermore, we describe a novel structure of an intermediate state of the protein with the external thin gate locked open by an inhibitor, 5-(2-naphthylmethyl)-L-hydantoin, which becomes a substrate when leucine 363 is changed to an alanine. We deduce the molecular events that underlie acquisition and transport of a ligand by Mhp1. PMID:24952894

  15. Absorption of Vitamin A and Carotenoids by the Enterocyte: Focus on Transport Proteins

    Directory of Open Access Journals (Sweden)

    Emmanuelle Reboul

    2013-09-01

    Full Text Available Vitamin A deficiency is a public health problem in most developing countries, especially in children and pregnant women. It is thus a priority in health policy to improve preformed vitamin A and/or provitamin A carotenoid status in these individuals. A more accurate understanding of the molecular mechanisms of intestinal vitamin A absorption is a key step in this direction. It was long thought that β-carotene (the main provitamin A carotenoid in human diet, and thus all carotenoids, were absorbed by a passive diffusion process, and that preformed vitamin A (retinol absorption occurred via an unidentified energy-dependent transporter. The discovery of proteins able to facilitate carotenoid uptake and secretion by the enterocyte during the past decade has challenged established assumptions, and the elucidation of the mechanisms of retinol intestinal absorption is in progress. After an overview of vitamin A and carotenoid fate during gastro-duodenal digestion, our focus will be directed to the putative or identified proteins participating in the intestinal membrane and cellular transport of vitamin A and carotenoids across the enterocyte (i.e., Scavenger Receptors or Cellular Retinol Binding Proteins, among others. Further progress in the identification of the proteins involved in intestinal transport of vitamin A and carotenoids across the enterocyte is of major importance for optimizing their bioavailability.

  16. A solute-binding protein for iron transport in Streptococcus iniae

    Directory of Open Access Journals (Sweden)

    Li Anxing

    2010-12-01

    Full Text Available Abstract Background Streptococcus iniae (S. iniae is a major pathogen that causes considerable morbidity and mortality in cultured fish worldwide. The pathogen's ability to adapt to the host affects the extent of infection, hence understanding the mechanisms by which S. iniae overcomes physiological stresses during infection will help to identify potential virulence determinants of streptococcal infection. Grow S. iniae under iron-restricted conditions is one approach for identifying host-specific protein expression. Iron plays an important role in many biological processes but it has low solubility under physiological condition. Many microorganisms have been shown to be able to circumvent this nutritional limitation by forming direct contacts with iron-containing proteins through ATP-binding cassette (ABC transporters. The ABC transporter superfamilies constitute many different systems that are widespread among living organisms with different functions, such as ligands translocation, mRNA translation, and DNA repair. Results An ABC transporter system, named as mtsABC (metal transport system was cloned from S. iniae HD-1, and was found to be involved in heme utilization. mtsABC is cotranscribed by three downstream genes, i.e., mtsA, mtsB, and mtsC. In this study, we cloned the first gene of the mtsABC transporter system (mtsA, and purified the corresponding recombinant protein MtsA. The analysis indicated that MtsA is a putative lipoprotein which binds to heme that can serve as an iron source for the microorganism, and is expressed in vivo during Kunming mice infection by S. iniae HD-1. Conclusions This is believed to be the first report on the cloning the ABC transporter lipoprotein from S. iniae genomic DNA. Together, our data suggested that MtsA is associated with heme, and is expressed in vivo during Kunming mice infection by S. iniae HD-1 which indicated that it can be a potential candidate for S. iniae subunit vaccine.

  17. Solitary BioY Proteins Mediate Biotin Transport into Recombinant Escherichia coli

    Science.gov (United States)

    Finkenwirth, Friedrich; Kirsch, Franziska

    2013-01-01

    Energy-coupling factor (ECF) transporters form a large group of vitamin uptake systems in prokaryotes. They are composed of highly diverse, substrate-specific, transmembrane proteins (S units), a ubiquitous transmembrane protein (T unit), and homo- or hetero-oligomeric ABC ATPases. Biotin transporters represent a special case of ECF-type systems. The majority of the biotin-specific S units (BioY) is known or predicted to interact with T units and ABC ATPases. About one-third of BioY proteins, however, are encoded in organisms lacking any recognizable T unit. This finding raises the question of whether these BioYs function as transporters in a solitary state, a feature ascribed to certain BioYs in the past. To address this question in living cells, an Escherichia coli K-12 derivative deficient in biotin synthesis and devoid of its endogenous high-affinity biotin transporter was constructed as a reference strain. This organism is particularly suited for this purpose because components of ECF transporters do not naturally occur in E. coli K-12. The double mutant was viable in media containing either high levels of biotin or a precursor of the downstream biosynthetic path. Importantly, it was nonviable on trace levels of biotin. Eight solitary bioY genes of proteobacterial origin were individually expressed in the reference strain. Each of the BioYs conferred biotin uptake activity on the recombinants, which was inferred from uptake assays with [3H]biotin and growth of the cells on trace levels of biotin. The results underscore that solitary BioY transports biotin across the cytoplasmic membrane. PMID:23836870

  18. Comprehensive identification of protein substrates of the Dot/Icm type IV transporter of Legionella pneumophila.

    Directory of Open Access Journals (Sweden)

    Wenhan Zhu

    2011-03-01

    Full Text Available A large number of proteins transferred by the Legionella pneumophila Dot/Icm system have been identified by various strategies. With no exceptions, these strategies are based on one or more characteristics associated with the tested proteins. Given the high level of diversity exhibited by the identified proteins, it is possible that some substrates have been missed in these screenings. In this study, we took a systematic method to survey the L. pneumophila genome by testing hypothetical orfs larger than 300 base pairs for Dot/Icm-dependent translocation. 798 of the 832 analyzed orfs were successfully fused to the carboxyl end of β-lactamase. The transfer of the fusions into mammalian cells was determined using the β-lactamase reporter substrate CCF4-AM. These efforts led to the identification of 164 proteins positive in translocation. Among these, 70 proteins are novel substrates of the Dot/Icm system. These results brought the total number of experimentally confirmed Dot/Icm substrates to 275. Sequence analysis of the C-termini of these identified proteins revealed that Lpg2844, which contains few features known to be important for Dot/Icm-dependent protein transfer can be translocated at a high efficiency. Thus, our efforts have identified a large number of novel substrates of the Dot/Icm system and have revealed the diverse features recognizable by this protein transporter.

  19. Inhibition of epithelial Na+ transport by atriopeptin, protein kinase c, and pertussis toxin

    International Nuclear Information System (INIS)

    Mohrmann, M.; Cantiello, H.F.; Ausiello, D.A.

    1987-01-01

    The authors have recently shown the selective inhibition of an amiloride-sensitive, conductive pathway for Na + by atrial natriuretic peptide and 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) in the renal epithelial cell line, LLC-PK i . Using 22 Na + fluxes, they further investigated the modulation of Na + transport by atrial natriuretic peptide and by agents that increase cGMP production, activate protein kinase c, or modulate guanine nucleotide regulatory protein function. Sodium nitroprusside increases intracellular cGMP concentrations without affecting cAMP concentrations and completely inhibits amiloride-sensitive Na + uptake in a time- and concentration-dependent manner. Oleoyl 2-acetylglycerol and phorbol 12-myristate 13-acetate, activators of protein kinase c, inhibit Na + uptake by 93 ± 13 and 51 ± 10%, respectively. Prolonged incubation with phorbol ester results in the downregulation of protein kinase c activity and reduces the inhibitory effect of atrial natriuretic peptide, suggesting that the action of this peptide involves stimulation of protein kinase c. Pertussis toxin, which induces the ADP-ribosylation of a 41-kDa guanine nucleotide regulatory protein in LLC-PK i cells, inhibits 22 Na + influx to the same extent as amiloride. Thus, increasing cGMP, activating protein kinase c, and ADP-ribosylating a guanine nucleotide regulatory protein all inhibit Na + uptake. These events may be sequentially involved in the action of atrial natriuretic peptide

  20. Niemann-pick type C1 (NPC1) overexpression alters cellular cholesterol homeostasis.

    Science.gov (United States)

    Millard, E E; Srivastava, K; Traub, L M; Schaffer, J E; Ory, D S

    2000-12-08

    The Niemann-Pick type C1 (NPC1) protein is a key participant in intracellular trafficking of low density lipoprotein cholesterol, but its role in regulation of sterol homeostasis is not well understood. To characterize further the function of NPC1, we generated stable Chinese hamster ovary (CHO) cell lines overexpressing the human NPC1 protein (CHO/NPC1). NPC1 overexpression increases the rate of trafficking of low density lipoprotein cholesterol to the endoplasmic reticulum and the rate of delivery of endosomal cholesterol to the plasma membrane (PM). CHO/NPC1 cells exhibit a 1.5-fold increase in total cellular cholesterol and up to a 2.9-fold increase in PM cholesterol. This increase in PM cholesterol is closely paralleled by a 3-fold increase in de novo cholesterol synthesis. Inhibition of cholesterol synthesis results in marked redistribution of PM cholesterol to intracellular sites, suggesting an unsuspected role for NPC1 in internalization of PM cholesterol. Despite elevated total cellular cholesterol, CHO/NPC1 cells exhibit increased cholesterol synthesis, which may be attributable to both resistance to oxysterol suppression of sterol-regulated gene expression and to reduced endoplasmic reticulum cholesterol levels under basal conditions. Taken together, these studies provide important new insights into the role of NPC1 in the determination of the levels and distribution of cellular cholesterol.

  1. Inhibition of the NLRP3 inflammasome attenuates foam cell formation of THP-1 macrophages by suppressing ox-LDL uptake and promoting cholesterol efflux.

    Science.gov (United States)

    Chen, Liang; Yao, Qiying; Xu, Siwei; Wang, Hongyan; Qu, Peng

    2018-01-01

    The NOD-like receptor family, pyrin domain-containing protein 3 (NLRP3) inflammasome plays an important role in the development of atherosclerosis. The activated NLRP3 inflammasome has been reported to promote macrophage foam cell formation, but not all studies have obtained the same result, and how NLRP3 inflammasome is involved in the formation of foam cells remains elusive. We used selective NLRP3 inflammasome inhibitors and NLRP3-deficient THP-1 cells to assess the effect of NLRP3 inflammasome inhibition on macrophage foam cell formation, oxidized low-density lipoprotein (ox-LDL) uptake, esterification, and cholesterol efflux, as well as the expression of associated proteins. Inhibition of the NLRP3 inflammasome attenuated foam cell formation, diminished ox-LDL uptake, and promoted cholesterol efflux from THP-1 macrophages. Moreover, it downregulated CD36, acyl coenzyme A: cholesterol acyltransferase-1 and neutral cholesterol ester hydrolase expression; upregulated ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) expression; but had no effect on the expression of scavenger receptor class A and ATP-binding cassette transporter G1. Collectively, our findings show that inhibition of the NLRP3 inflammasome decreases foam cell formation of THP-1 macrophages via suppression of ox-LDL uptake and enhancement of cholesterol efflux, which may be due to downregulation of CD36 expression and upregulation of ABCA1 and SR-BI expression, respectively. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. The Small Protein SgrT Controls Transport Activity of the Glucose-Specific Phosphotransferase System.

    Science.gov (United States)

    Lloyd, Chelsea R; Park, Seongjin; Fei, Jingyi; Vanderpool, Carin K

    2017-06-01

    The bacterial small RNA (sRNA) SgrS has been a fruitful model for discovery of novel RNA-based regulatory mechanisms and new facets of bacterial physiology and metabolism. SgrS is one of only a few characterized dual-function sRNAs. SgrS can control gene expression posttranscriptionally via sRNA-mRNA base-pairing interactions. Its second function is coding for the small protein SgrT. Previous work demonstrated that both functions contribute to relief of growth inhibition caused by glucose-phosphate stress, a condition characterized by disrupted glycolytic flux and accumulation of sugar phosphates. The base-pairing activity of SgrS has been the subject of numerous studies, but the activity of SgrT is less well characterized. Here, we provide evidence that SgrT acts to specifically inhibit the transport activity of the major glucose permease PtsG. Superresolution microscopy demonstrated that SgrT localizes to the cell membrane in a PtsG-dependent manner. Mutational analysis determined that residues in the N-terminal domain of PtsG are important for conferring sensitivity to SgrT-mediated inhibition of transport activity. Growth assays support a model in which SgrT-mediated inhibition of PtsG transport activity reduces accumulation of nonmetabolizable sugar phosphates and promotes utilization of alternative carbon sources by modulating carbon catabolite repression. The results of this study expand our understanding of a basic and well-studied biological problem, namely, how cells coordinate carbohydrate transport and metabolism. Further, this work highlights the complex activities that can be carried out by sRNAs and small proteins in bacteria. IMPORTANCE Sequencing, annotation and investigation of hundreds of bacterial genomes have identified vast numbers of small RNAs and small proteins, the majority of which have no known function. In this study, we explore the function of a small protein that acts in tandem with a well-characterized small RNA during metabolic

  3. Evidence of G-protein-coupled receptor and substrate transporter heteromerization at a single molecule level.

    Science.gov (United States)

    Fischer, Jana; Kleinau, Gunnar; Rutz, Claudia; Zwanziger, Denise; Khajavi, Noushafarin; Müller, Anne; Rehders, Maren; Brix, Klaudia; Worth, Catherine L; Führer, Dagmar; Krude, Heiko; Wiesner, Burkhard; Schülein, Ralf; Biebermann, Heike

    2018-06-01

    G-protein-coupled receptors (GPCRs) can constitute complexes with non-GPCR integral membrane proteins, while such interaction has not been demonstrated at a single molecule level so far. We here investigated the potential interaction between the thyrotropin receptor (TSHR) and the monocarboxylate transporter 8 (MCT8), a member of the major facilitator superfamily (MFS), using fluorescence cross-correlation spectroscopy (FCCS). Both the proteins are expressed endogenously on the basolateral plasma membrane of the thyrocytes and are involved in stimulation of thyroid hormone production and release. Indeed, we demonstrate strong interaction between both the proteins which causes a suppressed activation of G q/11 by TSH-stimulated TSHR. Thus, we provide not only evidence for a novel interaction between the TSHR and MCT8, but could also prove this interaction on a single molecule level. Moreover, this interaction forces biased signaling at the TSHR. These results are of general interest for both the GPCR and the MFS research fields.

  4. Mechanisms of EHD/RME-1 Protein Function in Endocytic Transport

    Science.gov (United States)

    Grant, Barth D.; Caplan, Steve

    2009-01-01

    The evolutionarily conserved Eps15 homology domain (EHD)/receptor-mediated endocytosis (RME)-1 family of C-terminal EH domain proteins has recently come under intense scrutiny because of its importance in intracellular membrane transport, especially with regard to the recycling of receptors from endosomes to the plasma membrane. Recent studies have shed new light on the mode by which these adenosine triphosphatases function on endosomal membranes in mammals and Caenorhabditis elegans. This review highlights our current understanding of the physiological roles of these proteins in vivo, discussing conserved features as well as emerging functional differences between individual mammalian paralogs. In addition, these findings are discussed in light of the identification of novel EHD/RME-1 protein and lipid interactions and new structural data for proteins in this family, indicating intriguing similarities to the Dynamin superfamily of large guanosine triphosphatases. PMID:18801062

  5. Ion Binding Energies Determining Functional Transport of ClC Proteins

    Science.gov (United States)

    Yu, Tao; Guo, Xu; Zou, Xian-Wu; Sang, Jian-Ping

    2014-06-01

    The ClC-type proteins, a large family of chloride transport proteins ubiquitously expressed in biological organisms, have been extensively studied for decades. Biological function of ClC proteins can be reflected by analyzing the binding situation of Cl- ions. We investigate ion binding properties of ClC-ec1 protein with the atomic molecular dynamics simulation approach. The calculated electrostatic binding energy results indicate that Cl- at the central binding site Scen has more binding stability than the internal binding site Sint. Quantitative comparison between the latest experimental heat release data isothermal titration calorimetry (ITC) and our calculated results demonstrates that chloride ions prefer to bind at Scen than Sint in the wild-type ClC-ec1 structure and prefer to bind at Sext and Scen than Sint in mutant E148A/E148Q structures. Even though the chloride ions make less contribution to heat release when binding to Sint and are relatively unstable in the Cl- pathway, they are still part contributors for the Cl- functional transport. This work provides a guide rule to estimate the importance of Cl- at the binding sites and how chloride ions have influences on the function of ClC proteins.

  6. A Salmonella typhimurium-translocated Glycerophospholipid:Cholesterol Acyltransferase Promotes Virulence by Binding to the RhoA Protein Switch Regions

    Energy Technology Data Exchange (ETDEWEB)

    LaRock, Doris L.; Brzovic, Peter S.; Levin, Itay; Blanc, Marie-Pierre; Miller, Samuel I.

    2012-08-24

    Salmonella enterica serovar typhimurium translocates a glycerophospholipid: cholesterol acyltransferase (SseJ) into the host cytosol after its entry into mammalian cells. SseJ is recruited to the cytoplasmic face of the host cell phagosome membrane where it is activated upon binding the small GTPase, RhoA. SseJ is regulated similarly to cognate eukaryotic effectors, as only the GTP-bound form of RhoA family members stimulates enzymatic activity. Using NMR and biochemistry, this work demonstrates that SseJ competes effectively with Rhotekin, ROCK, and PKN1 in binding to a similar RhoA surface. The RhoA surface that binds SseJ includes the regulatory switch regions that control activation of mammalian effectors. These data were used to create RhoA mutants with altered SseJ binding and activation. This structure-function analysis supports a model in which SseJ activation occurs predominantly through binding to residues within switch region II. We further defined the nature of the interaction between SseJ and RhoA by constructing SseJ mutants in the RhoA binding surface. These data indicate that SseJ binding to RhoA is required for recruitment of SseJ to the endosomal network and for full Salmonella virulence for inbred susceptible mice, indicating that regulation of SseJ by small GTPases is an important virulence strategy of this bacterial pathogen. The dependence of a bacterial effector on regulation by a mammalian GTPase defines further how intimately host pathogen interactions have coevolved through similar and divergent evolutionary strategies.

  7. Protein Kinases C-Mediated Regulations of Drug Transporter Activity, Localization and Expression

    Directory of Open Access Journals (Sweden)

    Abdullah Mayati

    2017-04-01

    Full Text Available Drug transporters are now recognized as major actors in pharmacokinetics, involved notably in drug–drug interactions and drug adverse effects. Factors that govern their activity, localization and expression are therefore important to consider. In the present review, the implications of protein kinases C (PKCs in transporter regulations are summarized and discussed. Both solute carrier (SLC and ATP-binding cassette (ABC drug transporters can be regulated by PKCs-related signaling pathways. PKCs thus target activity, membrane localization and/or expression level of major influx and efflux drug transporters, in various normal and pathological types of cells and tissues, often in a PKC isoform-specific manner. PKCs are notably implicated in membrane insertion of bile acid transporters in liver and, in this way, are thought to contribute to cholestatic or choleretic effects of endogenous compounds or drugs. The exact clinical relevance of PKCs-related regulation of drug transporters in terms of drug resistance, pharmacokinetics, drug–drug interactions and drug toxicity remains however to be precisely determined. This issue is likely important to consider in the context of the development of new drugs targeting PKCs-mediated signaling pathways, for treating notably cancers, diabetes or psychiatric disorders.

  8. Specificity of the second binding protein of the peptide ABC-transporter (Dpp) of Lactococcus lactis IL1403

    NARCIS (Netherlands)

    Sanz, Y; Toldra, F; Renault, P; Poolman, B

    2003-01-01

    The genome sequence of Lactococcus lactis IL1403 revealed the presence of a putative peptide-binding protein-dependent ABC-transporter (Dpp). The genes for two peptide-binding proteins (dppA and dppP) precede the membrane components, which include two transmembrane protein genes (dppB and dppC) and

  9. Identification of mitochondrial carriers in Saccharomyces cerevisiae by transport assay of reconstituted recombinant proteins.

    Science.gov (United States)

    Palmieri, Ferdinando; Agrimi, Gennaro; Blanco, Emanuela; Castegna, Alessandra; Di Noia, Maria A; Iacobazzi, Vito; Lasorsa, Francesco M; Marobbio, Carlo M T; Palmieri, Luigi; Scarcia, Pasquale; Todisco, Simona; Vozza, Angelo; Walker, John

    2006-01-01

    The inner membranes of mitochondria contain a family of carrier proteins that are responsible for the transport in and out of the mitochondrial matrix of substrates, products, co-factors and biosynthetic precursors that are essential for the function and activities of the organelle. This family of proteins is characterized by containing three tandem homologous sequence repeats of approximately 100 amino acids, each folded into two transmembrane alpha-helices linked by an extensive polar loop. Each repeat contains a characteristic conserved sequence. These features have been used to determine the extent of the family in genome sequences. The genome of Saccharomyces cerevisiae contains 34 members of the family. The identity of five of them was known before the determination of the genome sequence, but the functions of the remaining family members were not. This review describes how the functions of 15 of these previously unknown transport proteins have been determined by a strategy that consists of expressing the genes in Escherichia coli or Saccharomyces cerevisiae, reconstituting the gene products into liposomes and establishing their functions by transport assay. Genetic and biochemical evidence as well as phylogenetic considerations have guided the choice of substrates that were tested in the transport assays. The physiological roles of these carriers have been verified by genetic experiments. Various pieces of evidence point to the functions of six additional members of the family, but these proposals await confirmation by transport assay. The sequences of many of the newly identified yeast carriers have been used to characterize orthologs in other species, and in man five diseases are presently known to be caused by defects in specific mitochondrial carrier genes. The roles of eight yeast mitochondrial carriers remain to be established.

  10. Effect of heat stress on protein utilization and nutrient transporters in meat-type chickens

    Science.gov (United States)

    Habashy, Walid S.; Milfort, Marie C.; Fuller, Alberta L.; Attia, Youssef A.; Rekaya, Romdhane; Aggrey, Samuel E.

    2017-12-01

    The aim of this study was to investigate the effect of heat stress (HS) on digestibility of protein and fat and the expression of nutrient transporters in broilers. Forty-eight male Cobb500 chicks were used in this study. At day 14, birds were randomly divided into two groups and kept under either constant normal temperature (25 °C) or high temperature (35 °C) in individual cages. Five birds per treatment at 1 and 12 days post-treatment were euthanized, and Pectoralis major ( P. major) and ileum were sampled for gene expression analysis. At day 33, ileal contents were collected and used for digestibility analysis. The total consumption and retention of protein and fat were significantly lower in the HS group compared to the control group. Meanwhile, the retention of crude protein per BWG was significantly higher in the HS group compared to the control group. In P. major and ileum tissues at day 1, transporters FATP1 and SGLT1 were down-regulated in the HS group. Meanwhile, FABP1 and PepT1 were down-regulated only in the ileum of the HS group. The converse was shown in P. major. The nutrient transporter FABP1 at day 12 post-HS was down-regulated in the P. major and ileum, but GLUT1 and PepT2 were down-regulated only in the ileum, and PepT1 was down-regulated only in the P. major compared with the control group. These changes in nutrient transporters suggest that high ambient temperature might change the ileum and P. major lipids, glucose, and oligopeptide transporters.

  11. Pectin penta-oligogalacturonide reduces cholesterol accumulation by promoting bile acid biosynthesis and excretion in high-cholesterol-fed mice.

    Science.gov (United States)

    Zhu, Ru-Gang; Sun, Yan-Di; Hou, Yu-Ting; Fan, Jun-Gang; Chen, Gang; Li, Tuo-Ping

    2017-06-25

    Haw pectin penta-oligogalacturonide (HPPS) has important role in improving cholesterol metabolism and promoting the conversion of cholesterol to bile acids (BA) in mice fed high-cholesterol diet (HCD). However, the mechanism is not clear. This study aims to investigate the effects of HPPS on cholesterol accumulation and the regulation of hepatic BA synthesis and transport in HCD-fed mice. Results showed that HPPS significantly decreased plasma and hepatic TC levels but increased plasma high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apoA-I) levels, compared to HCD. BA analysis showed that HPPS markedly decreased hepatic and small intestine BA levels but increased the gallbladder BA levels, and finally decreased the total BA pool size, compared to HCD. Studies of molecular mechanism revealed that HPPS promoted hepatic ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), and scavenger receptor BI (SR-BI) expression but did not affect ATB binding cassette transporter G5/G8 (ABCG5/8) expression. HPPS inactivated hepatic farnesoid X receptor (FXR) and target genes expression, which resulted in significant increase of cholesterol 7α-hydroxylase 1 (CYP7A1) and sterol 12α-hydroxylase (CYP8B1) expression, with up-regulations of 204.2% and 33.5% for mRNA levels, respectively, compared with HCD. In addition, HPPS markedly enhanced bile salt export pump (BSEP) expression but didn't affect the sodium/taurocholate co-transporting polypeptide (NTCP) expression. In conclusion, the study revealed that HPPS reduced cholesterol accumulation by promoting BA synthesis in the liver and excretion in the feces, and might promote macrophage-to-liver reverse cholesterol transport (RCT) but did not liver-to-fecal RCT. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Cytoskeleton-centric protein transportation by exosomes transforms tumor-favorable macrophages

    Science.gov (United States)

    Cui, Yizhi; Zhou, Yanlong; Yin, Xingfeng; Guo, Jiahui; Zhang, Gong; Wang, Tong; He, Qing-Yu

    2016-01-01

    The exosome is a key initiator of pre-metastatic niche in numerous cancers, where macrophages serve as primary inducers of tumor microenvironment. However, the proteome that can be exosomally transported from cancer cells to macrophages has not been sufficiently characterized so far. Here, we used colorectal cancer (CRC) exosomes to educate tumor-favorable macrophages. With a SILAC-based mass spectrometry strategy, we successfully traced the proteome transported from CRC exosomes to macrophages. Such a proteome primarily focused on promoting cytoskeleton rearrangement, which was biologically validated with multiple cell lines. We reproduced the exosomal transportation of functional vimentin as a proof-of-concept example. In addition, we found that some CRC exosomes could be recognized by macrophages via Fc receptors. Therefore, we revealed the active and necessary role of exosomes secreted from CRC cells to transform cancer-favorable macrophages, with the cytoskeleton-centric proteins serving as the top functional unit. PMID:27602764

  13. Maintenance of asymmetric cellular localization of an auxin transport protein through interaction with the actin cytoskeleton

    Science.gov (United States)

    Muday, G. K.

    2000-01-01

    In shoots, polar auxin transport is basipetal (that is, from the shoot apex toward the base) and is driven by the basal localization of the auxin efflux carrier complex. The focus of this article is to summarize the experiments that have examined how the asymmetric distribution of this protein complex is controlled and the significance of this polar distribution. Experimental evidence suggests that asymmetries in the auxin efflux carrier may be established through localized secretion of Golgi vesicles, whereas an attachment of a subunit of the efflux carrier to the actin cytoskeleton may maintain this localization. In addition, the idea that this localization of the efflux carrier may control both the polarity of auxin movement and more globally regulate developmental polarity is explored. Finally, evidence indicating that the gravity vector controls auxin transport polarity is summarized and possible mechanisms for the environmentally induced changes in auxin transport polarity are discussed.

  14. Cytoskeleton-centric protein transportation by exosomes transforms tumor-favorable macrophages.

    Science.gov (United States)

    Chen, Zhipeng; Yang, Lijuan; Cui, Yizhi; Zhou, Yanlong; Yin, Xingfeng; Guo, Jiahui; Zhang, Gong; Wang, Tong; He, Qing-Yu

    2016-10-11

    The exosome is a key initiator of pre-metastatic niche in numerous cancers, where macrophages serve as primary inducers of tumor microenvironment. However, the proteome that can be exosomally transported from cancer cells to macrophages has not been sufficiently characterized so far. Here, we used colorectal cancer (CRC) exosomes to educate tumor-favorable macrophages. With a SILAC-based mass spectrometry strategy, we successfully traced the proteome transported from CRC exosomes to macrophages. Such a proteome primarily focused on promoting cytoskeleton rearrangement, which was biologically validated with multiple cell lines. We reproduced the exosomal transportation of functional vimentin as a proof-of-concept example. In addition, we found that some CRC exosomes could be recognized by macrophages via Fc receptors. Therefore, we revealed the active and necessary role of exosomes secreted from CRC cells to transform cancer-favorable macrophages, with the cytoskeleton-centric proteins serving as the top functional unit.

  15. Specific changes in rapidly transported proteins during regeneration of the goldfish optic nerve

    International Nuclear Information System (INIS)

    Benowitz, L.I.; Shashoua, V.E.; Yoon, M.G.

    1981-01-01

    Double labeling methods were used to identify changes in the complement of proteins synthesized in the retinal ganglion cells and transported down the optic nerve during the process of axonal regeneration. Eight to 62 days after goldfish underwent a unilateral optic nerve crush, one eye was labeled with [3H]-, the other with [14C]proline. Control and regenerating optic nerves were dissected out and homogenized together after 5 hr, a time which allowed us to examine selectively membrane-bound components which migrate in the rapid phase of axoplasmic transport. Proteins from the two sides were so-purified and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Analysis of the 3H and 14C incorporation patterns along the gels revealed a radical shift away from the normal labeling spectrum during regeneration, with selective changes in labeling at particular molecular weights varying over a 3-fold range. Eight days after crushing the optic nerve, the greatest increases in labeling were seen for material with apparent molecular weights of 24,000 to 27,000, 44,000, and 210,000 daltons. These peaks declined thereafter, and on days 29 to 39, the most prominent increases were at 110,000 to 140,000 daltons. These studies indicate a continuously changing pattern in the synthesis and/or degradation of proteins that are rapidly transported down the optic nerve during regeneration and point to molecular species potential significance in the establishment of the visual map upon the brain

  16. Aquaporin-11: A channel protein lacking apparent transport function expressed in brain

    Directory of Open Access Journals (Sweden)

    Tsunenari Takashi

    2006-05-01

    Full Text Available Abstract Background The aquaporins are a family of integral membrane proteins composed of two subfamilies: the orthodox aquaporins, which transport only water, and the aquaglyceroporins, which transport glycerol, urea, or other small solutes. Two recently described aquaporins, numbers 11 and 12, appear to be more distantly related to the other mammalian aquaporins and aquaglyceroporins. Results We report on the characterization of Aquaporin-11 (AQP11. AQP11 RNA and protein is found in multiple rat tissues, including kidney, liver, testes and brain. AQP11 has a unique distribution in brain, appearing in Purkinje cell dendrites, hippocampal neurons of CA1 and CA2, and cerebral cortical neurons. Immunofluorescent staining of Purkinje cells indicates that AQP11 is intracellular. Unlike other aquaporins, Xenopus oocytes expressing AQP11 in the plasma membrane failed to transport water, glycerol, urea, or ions. Conclusion AQP11 is functionally distinct from other proteins of the aquaporin superfamily and could represent a new aquaporin subfamily. Further studies are necessary to elucidate the role of AQP11 in the brain.

  17. A FYVE zinc finger domain protein specifically links mRNA transport to endosome trafficking

    Science.gov (United States)

    Pohlmann, Thomas; Baumann, Sebastian; Haag, Carl; Albrecht, Mario; Feldbrügge, Michael

    2015-01-01

    An emerging theme in cellular logistics is the close connection between mRNA and membrane trafficking. A prominent example is the microtubule-dependent transport of mRNAs and associated ribosomes on endosomes. This coordinated process is crucial for correct septin filamentation and efficient growth of polarised cells, such as fungal hyphae. Despite detailed knowledge on the key RNA-binding protein and the molecular motors involved, it is unclear how mRNAs are connected to membranes during transport. Here, we identify a novel factor containing a FYVE zinc finger domain for interaction with endosomal lipids and a new PAM2-like domain required for interaction with the MLLE domain of the key RNA-binding protein. Consistently, loss of this FYVE domain protein leads to specific defects in mRNA, ribosome, and septin transport without affecting general functions of endosomes or their movement. Hence, this is the first endosomal component specific for mRNP trafficking uncovering a new mechanism to couple mRNPs to endosomes. DOI: http://dx.doi.org/10.7554/eLife.06041.001 PMID:25985087

  18. A FYVE zinc finger domain protein specifically links mRNA transport to endosome trafficking.

    Science.gov (United States)

    Pohlmann, Thomas; Baumann, Sebastian; Haag, Carl; Albrecht, Mario; Feldbrügge, Michael

    2015-05-18

    An emerging theme in cellular logistics is the close connection between mRNA and membrane trafficking. A prominent example is the microtubule-dependent transport of mRNAs and associated ribosomes on endosomes. This coordinated process is crucial for correct septin filamentation and efficient growth of polarised cells, such as fungal hyphae. Despite detailed knowledge on the key RNA-binding protein and the molecular motors involved, it is unclear how mRNAs are connected to membranes during transport. Here, we identify a novel factor containing a FYVE zinc finger domain for interaction with endosomal lipids and a new PAM2-like domain required for interaction with the MLLE domain of the key RNA-binding protein. Consistently, loss of this FYVE domain protein leads to specific defects in mRNA, ribosome, and septin transport without affecting general functions of endosomes or their movement. Hence, this is the first endosomal component specific for mRNP trafficking uncovering a new mechanism to couple mRNPs to endosomes.

  19. Regulation of neuronal APL-1 expression by cholesterol starvation.

    Directory of Open Access Journals (Sweden)

    Mary Wiese

    Full Text Available BACKGROUND: Alzheimer's disease (AD is a neurodegenerative disorder characterized by the deposition of β-amyloid plaques composed primarily of the amyloid-β peptide, a cleavage product of amyloid precursor protein (APP. While mutations in APP lead to the development of Familial Alzheimer's Disease (FAD, sporadic AD has only one clear genetic modifier: the ε4 allele of the apolipoprotein E (ApoE gene. Cholesterol starvation in Caenorhabditis elegans leads to molting and arrest phenotypes similar to loss-of-function mutants of the APP ortholog, apl-1 (amyloid precursor-like protein 1, and lrp-1 (lipoprotein receptor-related protein 1, suggesting a potential interaction between apl-1 and cholesterol metabolism. METHODOLOGY/PRINCIPAL FINDINGS: Previously, we found that RNAi knock-down of apl-1 leads to aldicarb hypersensitivity, indicating a defect in synaptic function. Here we find the same defect is recapitulated during lrp-1 knock-down and by cholesterol starvation. A cholesterol-free diet or loss of lrp-1 directly affects APL-1 levels as both lead to loss of APL-1::GFP fluorescence in neurons. However, loss of cholesterol does not affect global transcription or protein levels as seen by qPCR and Western blot. CONCLUSIONS: Our results show that cholesterol and lrp-1 are involved in the regulation of synaptic transmission, similar to apl-1. Both are able to modulate APL-1 protein levels in neurons, however cholesterol changes do not affect global apl-1 transcription or APL-1 protein indicating the changes are specific to neurons. Thus, regulation of synaptic transmission and molting by LRP-1 and cholesterol may be mediated by their ability to control APL-1 neuronal protein expression.

  20. Relations Between Atherogenic Index of Plasma, Ratio of Small Dense Low Density Lipoprotein/Lecithin Cholesterol Acyl Transferase and Ratio of Small Dense Low Density Lipoprotein/Cholesteryl Ester Transfer Protein of Controlled and Uncontrolled Type 2 DM

    Directory of Open Access Journals (Sweden)

    Ellis Susanti

    2009-08-01

    Full Text Available BACKGROUND: Patients with Diabetes Melitus are proven to be prone to atherosclerosis and coronary heart disease, especially type 2 Diabetes Melitus (T2DM patient who have higher risk and mortality for cardiovascular risk factor. The Dyslipidemia condition is very common in T2DM as one of the risk factors. Diabetic dyslipidemia is marked by the increased triglyceride (TG, low HDL cholesterol (HDL-C, and increased small dense LDL and apolipoprotein B. Therefore the aim of this study is to assess the differential and correlation between Atherogenic Index of Plasma (AIP, ratio of small dense low density lipoprotein (sdLDL/lecithin cholesterol acyl transferase (LCAT and ratio of sdLDL/cholesteryl ester transfer protein (CETP of controlled and uncontrolled T2DM. METHODS: This study was observational with cross sectional design. In total of 72 patients with T2DM consist of 36 controlled and 36 uncontrolled, participated in this study. The serum TG, HDL-C, sdLDL, LCAT and CETP were examined in their relationship with to T2DM risk. RESULTS: The results of the study indicate that the AIP (p<0.001 increase controlled and uncontrolled T2DM and the ratio of sdLDL/CETP (p=0.004, odds ratio of AIP was 4 (95% CI: 1.501-10.658 and odds ratio of sdLDL/CETP ratio was 4 (95% CI: 1.501-10.658 in uncontrolled T2DM. CONCLUSIONS: This study showed that the AIP and ratio of small dense LDL/CETP had a significant correlation with the uncontrolled T2DM. The AIP and ratio of small dense LDL/CETP increase was found at the uncontrolled T2DM to be 4 times greater than the controlled T2DM. KEYWORDS: T2DM, atherosclerosis, atherogenic index of plasma, small dense LDL, LCAT, CETP, ratio of sdLDL/LCAT, ratio of sdLDL/CETP.

  1. Effects of dietary fucoxanthin on cholesterol metabolism in diabetic/obese KK-Ay mice

    Directory of Open Access Journals (Sweden)

    Beppu Fumiaki

    2012-09-01

    Full Text Available Abstract Background Fucoxanthin is a xanthophyll present in brown seaweeds and has several beneficial effects, including anti-obesity and anti-diabetic effects. However, we and another group previously observed that fucoxanthin increases serum cholesterol levels in rodents. Cholesterol is an important component of cell membranes and biosynthesis of bile acids. Serum cholesterol levels are also closely associated with atherosclerosis. Therefore, we sought to identify the mechanism underlying the increase in serum cholesterol levels by fucoxanthin. Methods Diabetic/obese KK-Ay mice were fed a diet containing 0.2% fucoxanthin for 4 weeks. The mice were sacrificed, and total blood samples were collected for the measurement of serum total cholesterol, HDL-cholesterol and non-HDL-cholesterol levels. Cholesterol content in tissues was also analyzed. Real-time PCR and Western blotting were performed to determine hepatic mRNA and protein expression of genes involved in cholesterol metabolism, respectively. Results Dietary fucoxanthin significantly increased serum HDL and non-HDL cholesterol levels, and reduced hepatic cholesterol content. In liver, the expression of SREBP1, SREBP2 and their target genes involved in cholesterol biosynthesis significantly increased and tended to increase in the fucoxanthin-fed mice, respectively. In contrast, hepatic levels of LDLR and SR-B1 proteins which is important factors for LDL-cholesterol and HDL-cholesterol uptake in the liver from serum, decreased to 60% and 80% in the fucoxanthin-fed mice, respectively, compared with the control mice. Further, we found that dietary fucoxanthin significantly increased the mRNA expression of proprotein convertase subtilisin/kexin type 9 (PCSK9, which enhances intracellular degradation of LDLR in lysosomes. Conclusions Fucoxanthin increased HDL-cholesterol and non-HDL-cholesterol levels in KK-Ay mice by inducing SREBP expression and reduced cholesterol uptake in the liver via

  2. Metalloido-porins: Essentiality of Nodulin 26-like intrinsic proteins in metalloid transport.

    Science.gov (United States)

    Pommerrenig, Benjamin; Diehn, Till Arvid; Bienert, Gerd Patrick

    2015-09-01

    Metalloids are a group of physiologically important elements ranging from the essential to the highly toxic. Arsenic, antimony, germanium, and tellurium are highly toxic to plants themselves and to consumers of metalloid-contaminated plants. Boron, silicon, and selenium fulfill essential or beneficial functions in plants. However, when present at high concentrations, boron and selenium cause toxicity symptoms that are detrimental to plant fitness and yield. Consequently, all plants require efficient membrane transport systems to control the uptake and extrusion of metalloids into or out of the plant and their distribution within the plant body. Several Nodulin 26-like intrinsic proteins (NIPs) that belong to the aquaporin plant water channel protein family facilitate the diffusion of uncharged metalloid species. Genetic, physiological, and molecular evidence is that NIPs from primitive to higher plants not only transport all environmentally important metalloids, but that these proteins have a major role in the uptake, translocation, and extrusion of metalloids in plants. As most of the metalloid-permeable NIP aquaporins are impermeable or are poorly permeable to water, these NIP channel proteins should be considered as physiologically essential metalloido-porins. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  3. N-MYC DOWN-REGULATED-LIKE Proteins Regulate Meristem Initiation by Modulating Auxin Transport and MAX2 Expression

    OpenAIRE

    Mudgil, Yashwanti; Ghawana, Sanjay; Jones, Alan M.

    2013-01-01

    Background N-MYC DOWN-REGULATED-LIKE (NDL) proteins interact with the G? subunit (AGB1) of the heterotrimeric G protein complex and play an important role in AGB1-dependent regulation of lateral root formation by affecting root auxin transport, auxin gradients and the steady-state levels of mRNA encoding the PIN-FORMED 2 and AUXIN 1 auxin transport facilitators. Auxin transport in aerial tissue follows different paths and utilizes different transporters than in roots; therefore, in the presen...

  4. In silico characterization of boron transporter (BOR1 protein sequences in Poaceae species

    Directory of Open Access Journals (Sweden)

    Ertuğrul Filiz

    2013-01-01

    Full Text Available Boron (B is essential for the plant growth and development, and its primary function is connected with formation of the cell wall. Moreover, boron toxicity is a shared problem in semiarid and arid regions. In this study, boron transporter protein (BOR1 sequences from some Poaceae species (Hordeum vulgare subsp. vulgare, Zea mays, Brachypodium distachyon, Oryza sativa subsp. japonica, Oryza sativa subsp. indica, Sorghum bicolor, Triticum aestivum were evaluated by bioinformatics tools. Physicochemical analyses revealed that most of BOR1 proteins were basic character and had generally aliphatic amino acids. Analysis of the domains showed that transmembrane domains were identified constantly and three motifs were detected with 50 amino acids length. Also, the motif SPNPWEPGSYDHWTVAKDMFNVPPAYIFGAFIPATMVAGLYYFDHSVASQ was found most frequently with 25 repeats. The phylogenetic tree showed divergence into two main clusters. B. distachyon species were clustered separately. Finally, this study contributes to the new BOR1 protein characterization in grasses and create scientific base for in silico analysis in future.

  5. Steric exclusion and protein conformation determine the localization of plasma membrane transporters.

    Science.gov (United States)

    Bianchi, Frans; Syga, Łukasz; Moiset, Gemma; Spakman, Dian; Schavemaker, Paul E; Punter, Christiaan M; Seinen, Anne-Bart; van Oijen, Antoine M; Robinson, Andrew; Poolman, Bert

    2018-02-05

    The plasma membrane (PM) of Saccharomyces cerevisiae contains membrane compartments, MCC/eisosomes and MCPs, named after the protein residents Can1 and Pma1, respectively. Using high-resolution fluorescence microscopy techniques we show that Can1 and the homologous transporter Lyp1 are able to diffuse into the MCC/eisosomes, where a limited number of proteins are conditionally trapped at the (outer) edge of the compartment. Upon addition of substrate, the immobilized proteins diffuse away from the MCC/eisosomes, presumably after taking a different conformation in the substrate-bound state. Our data indicate that the mobile fraction of all integral plasma membrane proteins tested shows extremely slow Brownian diffusion through most of the PM. We also show that proteins with large cytoplasmic domains, such as Pma1 and synthetic chimera of Can1 and Lyp1, are excluded from the MCC/eisosomes. We hypothesize that the distinct localization patterns found for these integral membrane proteins in S. cerevisiae arises from a combination of slow lateral diffusion, steric exclusion, and conditional trapping in membrane compartments.

  6. Enhanced hepatic apoA-I secretion and peripheral efflux of cholesterol and phospholipid in CD36 null mice.

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    Pin Yue

    2010-03-01

    Full Text Available CD36 facilitates oxidized low density lipoprotein uptake and is implicated in development of atherosclerotic lesions. CD36 also binds unmodified high and very low density lipoproteins (HDL, VLDL but its role in the metabolism of these particles is unclear. Several polymorphisms in the CD36 gene were recently shown to associate with serum HDL cholesterol. To gain insight into potential mechanisms for these associations we examined HDL metabolism in CD36 null (CD36(-/- mice. Feeding CD36(-/- mice a high cholesterol diet significantly increased serum HDL, cholesterol and phospholipids, as compared to wild type mice. HDL apolipoproteins apoA-I and apoA-IV were increased and shifted to higher density HDL fractions suggesting altered particle maturation. Clearance of dual-labeled HDL was unchanged in CD36(-/- mice and cholesterol uptake from HDL or LDL by isolated CD36(-/- hepatocytes was unaltered. However, CD36(-/- hepatocytes had higher cholesterol and phospholipid efflux rates. In addition, expression and secretion of apoA-I and apoA-IV were increased reflecting enhanced PXR. Similar to hepatocytes, cholesterol and phospholipid efflux were enhanced in CD36(-/- macrophages without changes in protein levels of ABCA1, ABCG1 or SR-B1. However, biotinylation assays showed increased surface ABCA1 localization in CD36(-/- cells. In conclusion, CD36 influences reverse cholesterol transport and hepatic ApoA-I production. Both pathways are enhanced in CD36 deficiency, increasing HDL concentrations, which suggests the potential benefit of CD36 inhibition.

  7. Effect of cholesterol nucleation-promoting activity on cholesterol solubilization in model bile

    NARCIS (Netherlands)

    Groen, A. K.; Ottenhoff, R.; Jansen, P. L.; van Marle, J.; Tytgat, G. N.

    1989-01-01

    Human bile contains a factor with cholesterol nucleation-promoting activity that binds to concanavalin A-Sepharose. In this study we have investigated the effect of this activity on the dynamics of lipid solubilization in supersaturated model bile. A concanavalin A binding protein fraction of human

  8. Olfactory marker protein: turnover and transport in normal and regenerating neurons

    International Nuclear Information System (INIS)

    Kream, R.M.; Margolis, F.L.

    1984-01-01

    A 19,000-dalton acidic protein designated olfactory marker protein (OMP) is a cell-specific marker of mature olfactory chemosensory neurons. Intranasal irrigation of mouse olfactory epithelium with [ 35 S]methionine labeled OMP to high specific activity. Turnover and transport characteristics of 35 S-labeled OMP were compared to those of 35 S-labeled global cytosol protein in groups of young, adult, and Triton-treated adult mice. The latter contained primarily large numbers of regenerating olfactory neurons. In olfactory epithelium of young and Triton-treated mice, the specific activity of OMP was three times that of global cytosol protein, whereas in adults the two measures were equal. In all three groups, however, the rate of degradation of OMP was roughly equal to that of cytosol protein (T1/2 . 5 to 6 days). By contrast, differences in T1/2 for OMP decline in the bulb of adult, young, and Triton-treated adult mice were highly significant (T1/2's of 9.3, 6.1, and 4 to 5 days, respectively; p . 0.001). The specific activity of [35S]methionine incorporated in OMP exceeded that of the free amino acid 5-fold, indicating minimal precursor reutilization during the course of our experiments. Turnover data indicate that increased isotope incorporation into OMP in the epithelium is matched by an accelerated rate of degradation in the bulb. This may be correlated with the physiological state or developmental age of the primary neurons since in young and Triton-treated adult mice, rapidly maturing ''young'' olfactory neurons represent a larger proportion of the total population than in adults. Thus, OMP behaves as a typical, relatively slowly transported soluble protein (v . 2 to 4 mm/day, slow component b)

  9. Cholesterol transfer from normal and atherogenic low density lipoproteins to Mycoplasma membranes

    International Nuclear Information System (INIS)

    Mitschelen, J.J.; St Clair, R.W.; Hester, S.H.

    1981-01-01

    The purpose of this study was to determine whether the free cholesterol of hypercholesterolemic low density lipoprotein from cholesterol-fed nonhuman primates has a greater potential for surface transfer to cell membranes than does the free cholesterol of normal low density lipoprotein. The low density lipoproteins were isolated from normal and hypercholesterolemic rhesus and cynomolgus monkeys, incubated with membranes from Acholeplasma laidlawii, a mycoplasma species devoid of cholesterol in its membranes, and the mass transfer of free cholesterol determined by measuring membrane cholesterol content. Since these membranes neither synthesize nor esterify cholesterol, nor degrade the protein or cholesterol ester moieties of low density lipoprotein, they are an ideal model with which to study differences in the cholesterol transfer potential of low density lipoprotein independent of the uptake of the intact low density lipoprotein particle. These studies indicate that, even though there are marked differences in the cholesterol composition of normal and hypercholesterolemic low density lipoproteins, this does not result in a greater chemical potential for surface transfer of free cholesterol. Consequently, if a difference in the surface transfer of free cholesterol is responsible for the enhanced ability of hypercholesterolemic low density lipoprotein to promote cellular cholesterol accumulation and, perhaps, also atherosclerosis, it must be the result of differences in the interaction to the hypercholesterolemic low density lipoprotein with the more complicated mammalian cell membranes, rather than differences in the chemical potential for cholesterol transfer

  10. The Down regulated in Adenoma (dra) gene encodes an intestine-specific membrane sulfate transport protein.

    Science.gov (United States)

    Silberg, D G; Wang, W; Moseley, R H; Traber, P G

    1995-05-19

    A gene has been described, Down Regulated in Adenoma (dra), which is expressed in normal colon but is absent in the majority of colon adenomas and adenocarcinomas. However, the function of this protein is unknown. Because of sequence similarity to a recently cloned membrane sulfate transporter in rat liver, the transport function of Dra was examined. We established that dra encodes for a Na(+)-independent transporter for both sulfate and oxalate using microinjected Xenopus oocytes as an assay system. Sulfate transport was sensitive to the anion exchange inhibitor DIDS (4,4'-diisothiocyano-2,2' disulfonic acid stilbene). Using an RNase protection assay, we found that dra mRNA expression is limited to the small intestine and colon in mouse, therefore identifying Dra as an intestine-specific sulfate transporter. dra also had a unique pattern of expression during intestinal development. Northern blot analysis revealed a low level of expression in colon at birth with a marked increase in the first 2 postnatal weeks. In contrast, there was a lower, constant level of expression in small intestine in the postnatal period. Caco-2 cells, a colon carcinoma cell line that differentiates over time in culture, demonstrated a marked induction of dra mRNA as cells progressed from the preconfluent (undifferentiated) to the postconfluent (differentiated) state. These results show that Dra is an intestine-specific Na(+)-independent sulfate transporter that has differential expression during colonic development. This functional characterization provides the foundation for investigation of the role of Dra in intestinal sulfate transport and in the malignant phenotype.

  11. CAVER 3.0: a tool for the analysis of transport pathways in dynamic protein structures.

    Science.gov (United States)

    Chovancova, Eva; Pavelka, Antonin; Benes, Petr; Strnad, Ondrej; Brezovsky, Jan; Kozlikova, Barbora; Gora, Artur; Sustr, Vilem; Klvana, Martin; Medek, Petr; Biedermannova, Lada; Sochor, Jiri; Damborsky, Jiri

    2012-01-01

    Tunnels and channels facilitate the transport of small molecules, ions and water solvent in a large variety of proteins. Characteristics of individual transport pathways, including their geometry, physico-chemical properties and dynamics are instrumental for understanding of structure-function relationships of these proteins, for the design of new inhibitors and construction of improved biocatalysts. CAVER is a software tool widely used for the identification and characterization of transport pathways in static macromolecular structures. Herein we present a new version of CAVER enabling automatic analysis of tunnels and channels in large ensembles of protein conformations. CAVER 3.0 implements new algorithms for the calculation and clustering of pathways. A trajectory from a molecular dynamics simulation serves as the typical input, while detailed characteristics and summary statistics of the time evolution of individual pathways are provided in the outputs. To illustrate the capabilities of CAVER 3.0, the tool was applied for the analysis of molecular dynamics simulation of the microbial enzyme haloalkane dehalogenase DhaA. CAVER 3.0 safely identified and reliably estimated the importance of all previously published DhaA tunnels, including the tunnels closed in DhaA crystal structures. Obtained results clearly demonstrate that analysis of molecular dynamics simulation is essential for the estimation of pathway characteristics and elucidation of the structural basis of the tunnel gating. CAVER 3.0 paves the way for the study of important biochemical phenomena in the area of molecular transport, molecular recognition and enzymatic catalysis. The software is freely available as a multiplatform command-line application at http://www.caver.cz.

  12. CAVER 3.0: a tool for the analysis of transport pathways in dynamic protein structures.

    Directory of Open Access Journals (Sweden)

    Eva Chovancova

    Full Text Available Tunnels and channels facilitate the transport of small molecules, ions and water solvent in a large variety of proteins. Characteristics of individual transport pathways, including their geometry, physico-chemical properties and dynamics are instrumental for understanding of structure-function relationships of these proteins, for the design of new inhibitors and construction of improved biocatalysts. CAVER is a software tool widely used for the identification and characterization of transport pathways in static macromolecular structures. Herein we present a new version of CAVER enabling automatic analysis of tunnels and channels in large ensembles of protein conformations. CAVER 3.0 implements new algorithms for the calculation and clustering of pathways. A trajectory from a molecular dynamics simulation serves as the typical input, while detailed characteristics and summary statistics of the time evolution of individual pathways are provided in the outputs. To illustrate the capabilities of CAVER 3.0, the tool was applied for the analysis of molecular dynamics simulation of the microbial enzyme haloalkane dehalogenase DhaA. CAVER 3.0 safely identified and reliably estimated the importance of all previously published DhaA tunnels, including the tunnels closed in DhaA crystal structures. Obtained results clearly demonstrate that analysis of molecular dynamics simulation is essential for the estimation of pathway characteristics and elucidation of the structural basis of the tunnel gating. CAVER 3.0 paves the way for the study of important biochemical phenomena in the area of molecular transport, molecular recognition and enzymatic catalysis. The software is freely available as a multiplatform command-line application at http://www.caver.cz.

  13. Molecular Diagnostics of Copper-Transporting Protein Mutations Allows Early Onset Individual Therapy of Menkes Disease.

    Science.gov (United States)

    Králík, L; Flachsová, E; Hansíková, H; Saudek, V; Zeman, J; Martásek, P

    2017-01-01

    Menkes disease is a severe X-linked recessive disorder caused by a defect in the ATP7A gene, which encodes a membrane copper-transporting ATPase. Deficient activity of the ATP7A protein results in decreased intestinal absorption of copper, low copper level in serum and defective distribution of copper in tissues. The clinical symptoms are caused by decreased activities of copper-dependent enzymes and include neurodegeneration, connective tissue disorders, arterial changes and hair abnormalities. Without therapy, the disease is fatal in early infancy. Rapid diagnosis of Menkes disease and early start of copper therapy is critical for the effectiveness of treatment. We report a molecular biology-based strategy that allows early diagnosis of copper transport defects and implementation of individual therapies before the full development of pathological symptoms. Low serum copper and decreased activity of copperdependent mitochondrial cytochrome c oxidase in isolated platelets found in three patients indicated a possibility of functional defects in copper-transporting proteins, especially in the ATPA7 protein, a copper- transporting P-type ATPase. Rapid mutational screening of the ATP7A gene using high-resolution melting analysis of DNA indicated presence of mutations in the patients. Molecular investigation for mutations in the ATP7A gene revealed three nonsense mutations: c.2170C>T (p.Gln724Ter); c.3745G>T (p.Glu1249Ter); and c.3862C>T (p.Gln1288Ter). The mutation c.3745G>T (p.Glu1249Ter) has not been identified previously. Molecular analysis of the ATOX1 gene as a possible modulating factor of Menkes disease did not reveal presence of pathogenic mutations. Molecular diagnostics allowed early onset of individual therapies, adequate genetic counselling and prenatal diagnosis in the affected families.

  14. CAVER 3.0: A Tool for the Analysis of Transport Pathways in Dynamic Protein Structures

    Science.gov (United States)

    Strnad, Ondrej; Brezovsky, Jan; Kozlikova, Barbora; Gora, Artur; Sustr, Vilem; Klvana, Martin; Medek, Petr; Biedermannova, Lada; Sochor, Jiri; Damborsky, Jiri

    2012-01-01

    Tunnels and channels facilitate the transport of small molecules, ions and water solvent in a large variety of proteins. Characteristics of individual transport pathways, including their geometry, physico-chemical properties and dynamics are instrumental for understanding of structure-function relationships of these proteins, for the design of new inhibitors and construction of improved biocatalysts. CAVER is a software tool widely used for the identification and characterization of transport pathways in static macromolecular structures. Herein we present a new version of CAVER enabling automatic analysis of tunnels and channels in large ensembles of protein conformations. CAVER 3.0 implements new algorithms for the calculation and clustering of pathways. A trajectory from a molecular dynamics simulation serves as the typical input, while detailed characteristics and summary statistics of the time evolution of individual pathways are provided in the outputs. To illustrate the capabilities of CAVER 3.0, the tool was applied for the analysis of molecular dynamics simulation of the microbial enzyme haloalkane dehalogenase DhaA. CAVER 3.0 safely identified and reliably estimated the importance of all previously published DhaA tunnels, including the tunnels closed in DhaA crystal structures. Obtained results clearly demonstrate that analysis of molecular dynamics simulation is essential for the estimation of pathway characteristics and elucidation of the structural basis of the tunnel gating. CAVER 3.0 paves the way for the study of important biochemical phenomena in the area of molecular transport, molecular recognition and enzymatic catalysis. The software is freely available as a multiplatform command-line application at http://www.caver.cz. PMID:23093919

  15. Expression of Duodenal Iron Transporter Proteins in Diabetic Patients with and without Iron Deficiency Anemia

    Directory of Open Access Journals (Sweden)

    Efrat Broide

    2018-01-01

    Full Text Available The role of iron transport proteins in the pathogenesis of anemia in patients with diabetes mellitus (T2DM is still unclear. We investigated the expression of duodenal transporter proteins in diabetic patients with and without iron deficiency anemia (IDA. Methods. Overall, 39 patients were included: 16 with T2DM and IDA (group A, 11 with T2DM without IDA (group B, and 12 controls (group C. Duodenal mucosal expression of divalent metal transporter 1 (DMT1, ferroportin 1 (FPN, hephaestin (HEPH, and transferrin receptor 1 (TfR was evaluated by Western blotting. Chronic disease activity markers were measured as well. Results. FPN expression was increased in group A compared to group B and controls: 1.17 (0.72–1.46, 0.76 (0.53–1.04, and 0.71 (0.64–0.86, respectively (p=0.011. TfR levels were over expressed in groups A and B compared to controls: 0.39 (0.26–0.61, 0.36 (0.24–0.43, and 0.18 (0.16–0.24, respectively, (p=0.004. The three groups did not differ significantly with regard to cellular HEPH and DMT1 expression. The normal CRP and serum ferritin levels, accompanied with normal FPN among diabetic patients without IDA, do not support the association of IDA with chronic inflammatory state. Conclusion. In patients with T2DM and IDA, duodenal iron transport protein expression might be dependent on body iron stores rather than by chronic inflammation or diabetes per se.

  16. Ursodeoxycholic Acid for the Treatment of Cholesterol Gallstones

    International Nuclear Information System (INIS)

    Zaater, M.K.

    2011-01-01

    Cholesterol is the principal constituent of more than three quarters of gallstones. Pure cholesterol crystals are quite soft, and protein contributes importantly to the strength of cholesterol stones. The risk of gallstones does not correlate with total serum cholesterol levels, but it does correlate with decreased high-density lipoprotein cholesterol and increased triglyceride levels. At least 10 percent of adults have gallstones where female: male ratio of about 2:1 in the younger age groups with increasing prevalence with age. Nine patients with gallstones (6 females and 3 males) were included in the study. Patients were treated with ursodeoxycholic acids tablets in two oral doses, one after breakfast, and the other after dinner for 9 months. Ultrasound examination was repeated every 3 months. Re-examination by abdominal ultrasonography revealed that gallstone 1 cm or less in diameter disappeared within 6 months, and the largest stone 3.06 cm in diameter disappeared within 9 months.

  17. Staphylococcus aureus manganese transport protein C (MntC is an extracellular matrix- and plasminogen-binding protein.

    Directory of Open Access Journals (Sweden)

    Natália Salazar

    Full Text Available Infections caused by Staphylococcus aureus--particularly nosocomial infections--represent a great concern. Usually, the early stage of pathogenesis consists on asymptomatic nasopharynx colonization, which could result in dissemination to other mucosal niches or invasion of sterile sites, such as blood. This pathogenic route depends on scavenging of nutrients as well as binding to and disrupting extracellular matrix (ECM. Manganese transport protein C (MntC, a conserved manganese-binding protein, takes part in this infectious scenario as an ion-scavenging factor and surprisingly as an ECM and coagulation cascade binding protein, as revealed in this work. This study showed a marked ability of MntC to bind to several ECM and coagulation cascade components, including laminin, collagen type IV, cellular and plasma fibronectin, plasminogen and fibrinogen by ELISA. The MntC binding to plasminogen appears to be related to the presence of surface-exposed lysines, since previous incubation with an analogue of lysine residue, ε-aminocaproic acid, or increasing ionic strength affected the interaction between MntC and plasminogen. MntC-bound plasminogen was converted to active plasmin in the presence of urokinase plasminogen activator (uPA. The newly released plasmin, in turn, acted in the cleavage of the α and β chains of fibrinogen. In conclusion, we describe a novel function for MntC that may help staphylococcal mucosal colonization and establishment of invasive disease, through the interaction with ECM and coagulation cascade host proteins. These data suggest that this potential virulence factor could be an adequate candidate to compose an anti-staphylococcal human vaccine formulation.

  18. The Success Story of LDL Cholesterol Lowering.

    Science.gov (United States)

    Pedersen, Terje R

    2016-02-19

    We can look back at >100 years of cholesterol research that has brought medicine to a stage where people at risk of severe or fatal coronary heart disease have a much better prognosis than before. This progress has not come about without resistance. Perhaps one of the most debated topics in medicine, the cholesterol controversy, could only be brought to rest through the development of new clinical research methods that were capable of taking advantage of the amazing achievements in basic and pharmacological science after the second World War. It was only after understanding the biochemistry and physiology of cholesterol synthesis, transport and clearance from the blood that medicine could take advantage of drugs and diets to reduce the risk of atherosclerotic diseases. This review points to the highlights of the history of low-density lipoprotein-cholesterol lowering, with the discovery of the low-density lipoprotein receptor and its physiology and not only the development of statins as the stellar moments but also the development of clinical trial methodology as an effective tool to provide scientifically convincing evidence. © 2016 American Heart Association, Inc.

  19. Temozolomide, sirolimus and chloroquine is a new therapeutic combination that synergizes to disrupt lysosomal function and cholesterol homeostasis in GBM cells.

    Science.gov (United States)

    Hsu, Sanford P C; Kuo, John S; Chiang, Hsin-Chien; Wang, Hsin-Ell; Wang, Yu-Shan; Huang, Cheng-Chung; Huang, Yi-Chun; Chi, Mau-Shin; Mehta, Minesh P; Chi, Kwan-Hwa

    2018-01-23

    Glioblastoma (GBM) cells are characterized by high phagocytosis, lipogenesis, exocytosis activities, low autophagy capacity and high lysosomal demand are necessary for survival and invasion. The lysosome stands at the cross roads of lipid biosynthesis, transporting, sorting between exogenous and endogenous cholesterol. We hypothesized that three already approved drugs, the autophagy inducer, sirolimus (rapamycin, Rapa), the autophagy inhibitor, chloroquine (CQ), and DNA alkylating chemotherapy, temozolomide (TMZ) could synergize against GBM. This repurposed triple therapy combination induced GBM apoptosis in vitro and inhibited GBM xenograft growth in vivo . Cytotoxicity is caused by induction of lysosomal membrane permeabilization and release of hydrolases, and may be rescued by cholesterol supplementation. Triple treatment inhibits lysosomal function, prevents cholesterol extraction from low density lipoprotein (LDL), and causes clumping of lysosome associated membrane protein-1 (LAMP-1) and lipid droplets (LD) accumulation. Co-treatment of the cell lines with inhibitor of caspases and cathepsin B only partially reverse of cytotoxicities, while N-acetyl cysteine (NAC) can be more effective. A combination of reactive oxygen species (ROS) generation from cholesterol depletion are the early event of underling mechanism. Cholesterol repletion abolished the ROS production and reversed the cytotoxicity from QRT treatment. The shortage of free cholesterol destabilizes lysosomal membranes converting aborted autophagy to apoptosis through either direct mitochondria damage or cathepsin B release. This promising anti-GBM triple therapy combination severely decreases mitochondrial function, induces lysosome-dependent apoptotic cell death, and is now poised for further clinical testing and validation.

  20. Andrographolide Inhibits Oxidized LDL-Induced Cholesterol Accumulation and Foam Cell Formation in Macrophages.

    Science.gov (United States)

    Lin, Hung-Chih; Lii, Chong-Kuei; Chen, Hui-Chun; Lin, Ai-Hsuan; Yang, Ya-Chen; Chen, Haw-Wen

    2018-01-01

    oxLDL is involved in the pathogenesis of atherosclerotic lesions through cholesterol accumulation in macrophage foam cells. Andrographolide, the bioactive component of Andrographis paniculata, possesses several biological activities such as anti-inflammatory, anti-oxidant, and anticancer functions. Scavenger receptors (SRs), including class A SR (SR-A) and CD36, are responsible for the internalization of oxLDL. In contrast, receptors for reverse cholesterol transport, including ABCA1 and ABCG1, mediate the efflux of cholesterol from macrophage foam cells. Transcription factor liver X receptor [Formula: see text] (LXR[Formula: see text] plays a key role in lipid metabolism and inflammation as well as in the regulation of ABCA1 and ABCG1 expression. Because of the contribution of inflammation to macrophage foam cell formation and the potent anti-inflammatory activity of andrographolide, we hypothesized that andrographolide might inhibit oxLDL-induced macrophage foam cell formation. The results showed that andrographolide reduced oxLDL-induced lipid accumulation in macrophage foam cells. Andrographolide decreased the mRNA and protein expression of CD36 by inducing the degradation of CD36 mRNA; however, andrographolide had no effect on SR-A expression. In contrast, andrographolide increased the mRNA and protein expression of ABCA1 and ABCG1, which were dependent on LXR[Formula: see text]. Andrographolide enhanced LXR[Formula: see text] nuclear translocation and DNA binding activity. Treatment with the LXR[Formula: see text] antagonist GGPP and transfection with LXR[Formula: see text] siRNA reversed the ability of andrographolide to stimulate ABCA1 and ABCG1 protein expression. In conclusion, inhibition of CD36-mediated oxLDL uptake and induction of ABCA1- and ABCG1-dependent cholesterol efflux are two working mechanisms by which andrographolide inhibits macrophage foam cell formation, which suggests that andrographolide could be a potential candidate to prevent

  1. Cytosolic cholesterol ester hydrolase in adrenal cortex

    OpenAIRE

    Tocher, Douglas R.

    1983-01-01

    Cholesterol ester hydrolase (CEH) in adrenocortical cytosol was known to be phosphorylated and activated, in response to ACTH in a cAMPdependent protein kinase mediated process. The purification of CEH from bovine adrenocortical cytosol was attempted. The use of detergents to solubilise the enzyme from lipid-rich aggregates was investigated and sodium cholate was found to be effective. A purification procedure using cholate solubilised enzyme was developed. The detergent int...

  2. Implication of the C terminus of the Prunus necrotic ringspot virus movement protein in cell-to-cell transport and in its interaction with the coat protein.

    Science.gov (United States)

    Aparicio, Frederic; Pallás, Vicente; Sánchez-Navarro, Jesús

    2010-07-01

    The movement protein (MP) of Prunus necrotic ringspot virus (PNRSV) is required for viral transport. Previous analysis with MPs of other members of the family Bromoviridae has shown that the C-terminal part of these MPs plays a critical role in the interaction with the cognate coat protein (CP) and in cell-to-cell transport. Bimolecular fluorescence complementation and overlay analysis confirm an interaction between the C-terminal 38 aa of PNRSV MP and its cognate CP. Mutational analysis of the C-terminal region of the PNRSV MP revealed that its C-terminal 38 aa are dispensable for virus transport, however, the 4 aa preceding the dispensable C terminus are necessary to target the MP to the plasmodesmata and for the functionality of the protein. The capacity of the PNRSV MP to use either a CP-dependent or a CP-independent cell-to-cell transport is discussed.

  3. The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA

    Energy Technology Data Exchange (ETDEWEB)

    Koropatkin, Nicole M.; Koppenaal, David W.; Pakrasi, Himadri B.; Smith, Thomas J.

    2007-01-26

    Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of the food chain by fixing carbon and nitrogen into cellular biomass. To compensate for the low selectivity of Rubisco for CO₂ over O₂, Cyanobacteria have developed highly efficient CO₂concentrating machinery of which the ABC transport system CmpABCD from Synechocystis PCC 6803 is one component. Here we describe the structure of the bicarbonate binding protein, CmpA, in the absence and presence of bicarbonate and carbonic acid. CmpA is highly homologous to the nitrate transport protein, NrtA. CmpA binds carbonic acid at the entrance to the ligand-binding pocket whereas bicarbonate binds in nearly an identical location compared to nitrate binding to NrtA. Unexpectedly, bicarbonate binding is accompanied by a metal ion, identified as Ca²⁺ via inductively coupled plasma optical emission spectrometry. The binding of bicarbonate and metal is highly cooperative and suggests that CmpA co-transports bicarbonate and calcium.

  4. Salvianolic acid B accelerated ABCA1-dependent cholesterol efflux by targeting PPAR-γ and LXRα

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Jianmei [Department of Endocrinology, Shandong Province Hospital Affiliated to Shandong University, 324# Jing 5 Road, Jinan 255021 (China); Department of Endocrinology, The First Hospital of Zibo, 4# E Mei Shan Dong Road, Zibo 255200 (China); Li, Bo, E-mail: libosubmit@163.com [Department of Cardiology, Central Hospital of Zibo, 54# Gong Qing Tuan Xi Road, Zibo, Shandong Province (China); Jing, Qingping [Department of Endocrinology, The First Hospital of Zibo, 4# E Mei Shan Dong Road, Zibo 255200 (China); Guan, Qingbo, E-mail: guanqingbosubmit@163.com [Department of Endocrinology, Shandong Province Hospital Affiliated to Shandong University, 324# Jing 5 Road, Jinan 255021 (China)

    2015-07-03

    Objectives: Cholesterol efflux has been thought to be the main and basic mechanism by which free cholesterol is transferred from extra hepatic cells to the liver or intestine for excretion. Salvianolic acid B (Sal B) has been widely used for the prevention and treatment of atherosclerotic diseases. Here, we sought to investigate the effects of Sal B on the cholesterol efflux in THP-1 macrophages. Methods: After PMA-stimulated THP-1 cells were exposed to 50 mg/L of oxLDL and [{sup 3}H] cholesterol (1.0 μCi/mL) for another 24 h, the effect of Sal B on cholesterol efflux was evaluated in the presence of apoA-1, HDL{sub 2} or HDL{sub 3}. The expression of ATP binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-gamma (PPAR-γ), and liver X receptor-alpha (LXRα) was detected both at protein and mRNA levels in THP-1 cells after the stimulation of Sal B. Meanwhile, specific inhibition of PPAR-γ and LXRα were performed to investigate the mechanism. Results: The results showed that Sal B significantly accelerated apoA-I- and HDL-mediated cholesterol efflux in both dose- and time-dependent manners. Meanwhile, Sal B treatment also enhanced the expression of ABCA1 at both mRNA and protein levels. Then the data demonstrated that Sal B increased the expression of PPAR-γ and LXRα. And the application of specific agonists and inhibitors of further confirmed that Sal exert the function through PPAR-γ and LXRα. Conclusion: These results demonstrate that Sal B promotes cholesterol efflux in THP-1 macrophages through ABCA1/PPAR-γ/LXRα pathway. - Highlights: • Sal B promotes the expression of ABCA1. • Sal B promotes cholesterol efflux in macrophages. • Sal B promotes the expression of ABCA1 and cholesterol efflux through PPAR-γ/LXRα signaling pathway.

  5. Changes to cholesterol trafficking in macrophages by Leishmania parasites infection.

    Science.gov (United States)

    Semini, Geo; Paape, Daniel; Paterou, Athina; Schroeder, Juliane; Barrios-Llerena, Martin; Aebischer, Toni

    2017-08-01

    Leishmania spp. are protozoan parasites that are transmitted by sandfly vectors during blood sucking to vertebrate hosts and cause a spectrum of diseases called leishmaniases. It has been demonstrated that host cholesterol plays an important role during Leishmania infection. Nevertheless, little is known about the intracellular distribution of this lipid early after internalization of the parasite. Here, pulse-chase experiments with radiolabeled cholesteryl esterified to fatty acids bound to low-density lipoproteins indicated that retention of this source of cholesterol is increased in parasite-containing subcellular fractions, while uptake is unaffected. This is correlated with a reduction or absence of detectable NPC1 (Niemann-Pick disease, type C1), a protein responsible for cholesterol efflux from endocytic compartments, in the Leishmania mexicana habitat and infected cells. Filipin staining revealed a halo around parasites within parasitophorous vacuoles (PV) likely representing free cholesterol accumulation. Labeling of host cell membranous cholesterol by fluorescent cholesterol species before infection revealed that this pool is also trafficked to the PV but becomes incorporated into the parasites' membranes and seems not to contribute to the halo detected by filipin. This cholesterol sequestration happened early after infection and was functionally significant as it correlated with the upregulation of mRNA-encoding proteins required for cholesterol biosynthesis. Thus, sequestration of cholesterol by Leishmania amastigotes early after infection provides a basis to understand perturbation of cholesterol-dependent processes in macrophages that were shown previously by others to be necessary for their proper function in innate and adaptive immune responses. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  6. Impaired reverse cholesterol transport and hepatic steatosis ...

    African Journals Online (AJOL)

    Laboratory of Research and Development in Traditional Chinese Medicine, Guangzhou, Guangdong 510095, PR China .... Strand cDNA Synthesis kit and the Maxima™ ..... hematopoietic stem cell proliferation and monocytosis: studies in ...

  7. Phylogenetic profiles of all membrane transport proteins of the malaria parasite highlight new drug targets

    Directory of Open Access Journals (Sweden)

    January Weiner 3rd

    2016-08-01

    Full Text Available In order to combat the on-going malaria epidemic, discovery of new drug targets remains vital. Proteins that are essential to survival and specific to malaria parasites are key candidates. To survive within host cells, the parasites need to acquire nutrients and dispose of waste products across multiple membranes. Additionally, like all eukaryotes, they must redistribute ions and organic molecules between their various internal membrane bound compartments. Membrane transport proteins mediate all of these processes and are considered important mediators of drug resistance as well as drug targets in their own right. Recently, using advanced experimental genetic approaches and streamlined life cycle profiling, we generated a large collection of Plasmodium berghei gene deletion mutants and assigned essential gene functions, highlighting potential targets for prophylactic, therapeutic, and transmission-blocking anti-malarial drugs. Here, we present a comprehensive orthology assignment of all Plasmodium falciparum putative membrane transport proteins and provide a detailed overview of the associated essential gene functions obtained through experimental genetics studies in human and murine model parasites. Furthermore, we discuss the phylogeny of selected potential drug targets identified in our functional screen. We extensively discuss the results in the context of the functional assignments obtained using gene targeting available to date.

  8. Ischemia - reperfusion induced changes in levels of ion transport proteins in gerbil brain

    International Nuclear Information System (INIS)

    Lehotsky, J.; Racay, P.; Kaplan, P.; Mezesova, V.; Raeymaekers, L.

    1998-01-01

    A quantitative Western blotting was used to asses the levels of ion transport proteins in gerbil brain in control and in animals after ischemic-reperfusion injury (IRI). The gene products of plasma membrane Ca 2+ pump (PMCA) were detected in the hippocampus, cerebral cortex and cerebellum. However, they showed a distinct distribution pattern. Inositol 1,4,5-triphosphate (Ins 3 ) receptor and reticular Ca 2+ pump are the most abundant in cerebellum and hippocampus. The IRI leads to a selective decrease in content of PMCA and InsP 3 receptor I isoforms. The levels of α 3 isoform of Na + pump and reticular proteins: Ca 2+ pump and calreticulin remained constant. InsP 3 receptor and organellar Ca 2+ (SERCA) are the most abundant in cerebellum and hippocampus. Ischemia and reperfusion up to 10 days leads to a signal decrease of PMCA immuno-signal. We suppose that alteration of number of ion transport proteins, can contribute to changes which participate or follow the delayed death of neurons in hippocampus. (authors)

  9. Cholesterol Balance in Prion Diseases and Alzheimer’s Disease

    Science.gov (United States)

    Hannaoui, Samia; Shim, Su Yeon; Cheng, Yo Ching; Corda, Erica; Gilch, Sabine

    2014-01-01

    Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI) anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD): whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD. PMID:25419621

  10. Cholesterol Balance in Prion Diseases and Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Samia Hannaoui

    2014-11-01

    Full Text Available Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD: whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD.

  11. Influence of insulin sensitivity and the TaqIB cholesteryl ester transfer protein gene polymorphism on plasma lecithin:cholesterol acyltransferase and lipid transfer protein activities and their response to hyperinsulinemia in non-diabetic men

    NARCIS (Netherlands)

    S.C. Riemens; A. van Tol (Arie); B.K. Stulp; R.P.F. Dullaart (Robin)

    1999-01-01

    textabstractLecithin:cholesteryl acyl transferase (LCAT), cholesteryl ester transfer protein (CETP), phospholipid transfer protein (PLTP), and lipoprotein lipases are involved in high density lipoprotein (HDL) metabolism. We evaluated the influence of insulin

  12. The breast cancer resistance protein transporter ABCG2 is expressed in the human kidney proximal tubule apical membrane.

    NARCIS (Netherlands)

    Huls, M.; Brown, C.D.; Windass, A.S.; Sayer, R.; Heuvel, J.J.M.W. van den; Heemskerk, S.; Russel, F.G.M.; Masereeuw, R.

    2008-01-01

    The Breast Cancer Resistance Protein (BCRP/ABCG2) is a transporter restricting absorption and enhancing excretion of many compounds including anticancer drugs. This transporter is highly expressed in many tissues; however, in human kidney, only the mRNA was found in contrast to the mouse kidney,

  13. Involvement of adenosine monophosphate activated kinase in interleukin-6 regulation of steroidogenic acute regulatory protein and cholesterol side chain cleavage enzyme in the bovine zona fasciculata and zona reticularis.

    Science.gov (United States)

    De Silva, Matharage S I; Dayton, Adam W; Rhoten, Lance R; Mallett, John W; Reese, Jared C; Squires, Mathieu D; Dalley, Andrew P; Porter, James P; Judd, Allan M

    2018-06-01

    In bovine adrenal zona fasciculata (ZF) and NCI-H295R cells, interleukin-6 (IL-6) increases cortisol release, increases expression of steroidogenic acute regulatory protein (StAR), cholesterol side chain cleavage enzyme (P450scc), and steroidogenic factor 1 (SF-1) (increases steroidogenic proteins), and decreases the expression of adrenal hypoplasia congenita-like protein (DAX-1) (inhibits steroidogenic proteins). In contrast, IL-6 decreases bovine adrenal zona reticularis (ZR) androgen release, StAR, P450scc, and SF-1 expression, and increases DAX-1 expression. Adenosine monophosphate (AMP) activated kinase (AMPK) regulates steroidogenesis, but its role in IL-6 regulation of adrenal steroidogenesis is unknown. In the present study, an AMPK activator (AICAR) increased (P < 0.01) NCI-H295R StAR promoter activity, StAR and P450scc expression, and the phosphorylation of AMPK (PAMPK) and acetyl-CoA carboxylase (PACC) (indexes of AMPK activity). In ZR (decreased StAR, P450scc, SF-1, increased DAX-1) (P < 0.01) and ZF tissues (increased StAR, P450scc, SF-1, decreased DAX-1) (P < 0.01), AICAR modified StAR, P450scc, SF-1 and DAX-1 mRNAs/proteins similar to the effects of IL-6. The activity (increased PAMPK and PACC) (P < 0.01) of AMPK in the ZF and ZR was increased by AICAR and IL-6. In support of an AMPK role in IL-6 ZF and ZR effects, the AMPK inhibitor compound C blocked (P < 0.01) the effects of IL-6 on the expression of StAR, P450scc, SF-1, and DAX-1. Therefore, IL-6 modification of the expression of StAR and P450scc in the ZF and ZR may involve activation of AMPK and these changes may be related to changes in the expression of SF-1 and DAX-1. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Golgi localized barley MTP8 proteins facilitate Mn transport

    DEFF Research Database (Denmark)

    Pedas, Pai Rosager; Schiller, Michaela; Hegelund, Josefine Nymark

    2014-01-01

    Many metabolic processes in plants are regulated by manganese (Mn) but limited information is available on the molecular mechanisms controlling cellular Mn homeostasis. In this study, a yeast assay was used to isolate and characterize two genes, MTP8.1 and MTP8.2 , which encode membrane...... in yeast, MTP8.1 and MTP8.2 were found to be Mn transporters catalysing Mn efflux in a similar manner as the Golgi localized endogenous yeast protein Pmr1p. The level of MTP8.1 transcripts in barley roots increased with external Mn supply ranging from deficiency to toxicity, while MTP8.2 transcripts...

  15. Simultaneous determination of glucose, triglycerides, urea, cholesterol, albumin and total protein in human plasma by Fourier transform infrared spectroscopy: direct clinical biochemistry without reagents.

    Science.gov (United States)

    Jessen, Torben E; Höskuldsson, Agnar T; Bjerrum, Poul J; Verder, Henrik; Sørensen, Lars; Bratholm, Palle S; Christensen, Bo; Jensen, Lene S; Jensen, Maria A B

    2014-09-01

    Direct measurement of chemical constituents in complex biologic matrices without the use of analyte specific reagents could be a step forward toward the simplification of clinical biochemistry. Problems related to reagents such as production errors, improper handling, and lot-to-lot variations would be eliminated as well as errors occurring during assay execution. We describe and validate a reagent free method for direct measurement of six analytes in human plasma based on Fourier-transform infrared spectroscopy (FTIR). Blood plasma is analyzed without any sample preparation. FTIR spectrum of the raw plasma is recorded in a sampling cuvette specially designed for measurement of aqueous solutions. For each analyte, a mathematical calibration process is performed by a stepwise selection of wavelengths giving the optimal least-squares correlation between the measured FTIR signal and the analyte concentration measured by conventional clinical reference methods. The developed calibration algorithms are subsequently evaluated for their capability to predict the concentration of the six analytes in blinded patient samples. The correlation between the six FTIR methods and corresponding reference methods were 0.87albumin and total protein in human plasma. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  16. Plasma Membrane-Located Purine Nucleotide Transport Proteins Are Key Components for Host Exploitation by Microsporidian Intracellular Parasites

    Science.gov (United States)

    Heinz, Eva; Hacker, Christian; Dean, Paul; Mifsud, John; Goldberg, Alina V.; Williams, Tom A.; Nakjang, Sirintra; Gregory, Alison; Hirt, Robert P.; Lucocq, John M.; Kunji, Edmund R. S.; Embley, T. Martin

    2014-01-01

    Microsporidia are obligate intracellular parasites of most animal groups including humans, but despite their significant economic and medical importance there are major gaps in our understanding of how they exploit infected host cells. We have investigated the evolution, cellular locations and substrate specificities of a family of nucleotide transport (NTT) proteins from Trachipleistophora hominis, a microsporidian isolated from an HIV/AIDS patient. Transport proteins are critical to microsporidian success because they compensate for the dramatic loss of metabolic pathways that is a hallmark of the group. Our data demonstrate that the use of plasma membrane-located nucleotide transport proteins (NTT) is a key strategy adopted by microsporidians to exploit host cells. Acquisition of an ancestral transporter gene at the base of the microsporidian radiation was followed by lineage-specific events of gene duplication, which in the case of T. hominis has generated four paralogous NTT transporters. All four T. hominis NTT proteins are located predominantly to the plasma membrane of replicating intracellular cells where they can mediate transport at the host-parasite interface. In contrast to published data for Encephalitozoon cuniculi, we found no evidence for the location for any of the T. hominis NTT transporters to its minimal mitochondria (mitosomes), consistent with lineage-specific differences in transporter and mitosome evolution. All of the T. hominis NTTs transported radiolabelled purine nucleotides (ATP, ADP, GTP and GDP) when expressed in Escherichia coli, but did not transport radiolabelled pyrimidine nucleotides. Genome analysis suggests that imported purine nucleotides could be used by T. hominis to make all of the critical purine-based building-blocks for DNA and RNA biosynthesis during parasite intracellular replication, as well as providing essential energy for parasite cellular metabolism and protein synthesis. PMID:25474405

  17. Plasma membrane-located purine nucleotide transport proteins are key components for host exploitation by microsporidian intracellular parasites.

    Directory of Open Access Journals (Sweden)

    Eva Heinz

    2014-12-01

    Full Text Available Microsporidia are obligate intracellular parasites of most animal groups including humans, but despite their significant economic and medical importance there are major gaps in our understanding of how they exploit infected host cells. We have investigated the evolution, cellular locations and substrate specificities of a family of nucleotide transport (NTT proteins from Trachipleistophora hominis, a microsporidian isolated from an HIV/AIDS patient. Transport proteins are critical to microsporidian success because they compensate for the dramatic loss of metabolic pathways that is a hallmark of the group. Our data demonstrate that the use of plasma membrane-located nucleotide transport proteins (NTT is a key strategy adopted by microsporidians to exploit host cells. Acquisition of an ancestral transporter gene at the base of the microsporidian radiation was followed by lineage-specific events of gene duplication, which in the case of T. hominis has generated four paralogous NTT transporters. All four T. hominis NTT proteins are located predominantly to the plasma membrane of replicating intracellular cells where they can mediate transport at the host-parasite interface. In contrast to published data for Encephalitozoon cuniculi, we found no evidence for the location for any of the T. hominis NTT transporters to its minimal mitochondria (mitosomes, consistent with lineage-specific differences in transporter and mitosome evolution. All of the T. hominis NTTs transported radiolabelled purine nucleotides (ATP, ADP, GTP and GDP when expressed in Escherichia coli, but did not transport radiolabelled pyrimidine nucleotides. Genome analysis suggests that imported purine nucleotides could be used by T. hominis to make all of the critical purine-based building-blocks for DNA and RNA biosynthesis during parasite intracellular replication, as well as providing essential energy for parasite cellular metabolism and protein synthesis.

  18. Functional modulation of the glutamate transporter variant GLT1b by the PDZ domain protein PICK1

    DEFF Research Database (Denmark)

    Søgaard, Rikke; Borre, Lars; Braunstein, Thomas H

    2013-01-01

    The dominant glutamate transporter isoform in the mammalian brain, GLT1, exists as at least three splice variants, GLT1a, GLT1b, and GLT1c. GLT1b interacts with the scaffold protein PICK1 (protein interacting with kinase C1), which is implicated in glutamatergic neurotransmission via its regulato...

  19. Metal-like transport in proteins: A new paradigm for biological electron transfer

    Science.gov (United States)

    Malvankar, Nikhil; Vargas, Madeline; Tuominen, Mark; Lovley, Derek

    2012-02-01

    Electron flow in biologically proteins generally occurs via tunneling or hopping and the possibility of electron delocalization has long been discounted. Here we report metal-like transport in protein nanofilaments, pili, of bacteria Geobacter sulfurreducens that challenges this long-standing belief [1]. Pili exhibit conductivities comparable to synthetic organic metallic nanostructures. The temperature, magnetic field and gate-voltage dependence of pili conductivity is akin to that of quasi-1D disordered metals, suggesting a metal-insulator transition. Magnetoresistance (MR) data provide evidence for quantum interference and weak localization at room temperature, as well as a temperature and field-induced crossover from negative to positive MR. Furthermore, pili can be doped with protons. Structural studies suggest the possibility of molecular pi stacking in pili, causing electron delocalization. Reducing the disorder increases the metallic nature of pili. These electronically functional proteins are a new class of electrically conductive biological proteins that can be used to generate future generation of inexpensive and environmentally-sustainable nanomaterials and nanolectronic devices such as transistors and supercapacitors. [1] Malvankar et al. Nature Nanotechnology, 6, 573-579 (2011)

  20. Regulation of motor proteins, axonal transport deficits and adult-onset neurodegenerative diseases.

    Science.gov (United States)

    Brady, Scott T; Morfini, Gerardo A

    2017-09-01

    Neurons affected in a wide variety of unrelated adult-onset neurodegenerative diseases (AONDs) typically exhibit a "dying back" pattern of degeneration, which is characterized by early deficits in synaptic function and neuritic pathology long before neuronal cell death. Consistent with this observation, multiple unrelated AONDs including Alzheimer's disease, Parkinson's disease, Huntington's disease, and several motor neuron diseases feature early alterations in kinase-based signaling pathways associated with deficits in axonal transport (AT), a complex cellular process involving multiple intracellular trafficking events powered by microtubule-based motor proteins. These pathogenic events have important therapeutic implications, suggesting that a focus on preservation of neuronal connections may be more effective to treat AONDs than addressing neuronal cell death. While the molecular mechanisms underlying AT abnormalities in AONDs are still being analyzed, evidence has accumulated linking those to a well-established pathological hallmark of multiple AONDs: altered patterns of neuronal protein phosphorylation. Here, we present a short overview on the biochemical heterogeneity of major motor proteins for AT, their regulation by protein kinases, and evidence revealing cell type-specific AT specializations. When considered together, these findings may help explain how independent pathogenic pathways can affect AT differentially in the context of each AOND. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Dynamic factors affecting gaseous ligand binding in an artificial oxygen transport protein.

    Science.gov (United States)

    Zhang, Lei; Andersen, Eskil M E; Khajo, Abdelahad; Magliozzo, Richard S; Koder, Ronald L

    2013-01-22

    We report the functional analysis of an artificial hexacoordinate oxygen transport protein, HP7, which operates via a mechanism similar to that of human neuroglobin and cytoglobin: the destabilization of one of two heme-ligating histidine residues. In the case of HP7, this is the result of the coupling of histidine side chain ligation with the burial of three charged glutamate residues on the same helix. Here we compare gaseous ligand binding, including rates, affinities, and oxyferrous state lifetimes, of both heme binding sites in HP7. We find that despite the identical sequence of helices in both binding sites, there are differences in oxygen affinity and oxyferrous state lifetime that may be the result of differences in the freedom of motion imposed by the candelabra fold on the two sites of the protein. We further examine the effect of mutational removal of the buried glutamates on function. Heme iron in the ferrous state of this mutant is rapidly oxidized when exposed to oxygen. Compared to that of HP7, the distal histidine affinity is increased by a 22-fold decrease in the histidine ligand off rate. Electron paramagnetic resonance comparison of these ferric hemoproteins demonstrates that the mutation increases the level of disorder at the heme binding site. Nuclear magnetic resonance-detected deuterium exchange demonstrates that the mutation greatly increases the degree of penetration of water into the protein core. The inability of the mutant protein to bind oxygen may be due to an increased level of water penetration, the large decrease in binding rate caused by the increase in distal histidine affinity, or a combination of the two factors. Together, these data underline the importance of the control of protein dynamics in the design of functional artificial proteins.

  2. Consuming a hypocaloric high fat low carbohydrate diet for 12 weeks lowers C-reactive protein, and raises serum adiponectin and high density lipoprotein-cholesterol in obese subjects.

    Science.gov (United States)

    Ruth, Megan R; Port, Ava M; Shah, Mitali; Bourland, Ashley C; Istfan, Nawfal W; Nelson, Kerrie P; Gokce, Noyan; Apovian, Caroline M

    2013-12-01

    High fat, low carbohydrate (HFLC) diets have become popular tools for weight management. We sought to determine the effects of a HFLC diet compared to a low fat high carbohydrate (LFHC) diet on the change in weight loss, cardiovascular risk factors and inflammation in subjects with obesity. Obese subjects (29.0-44.6 kg/m2) recruited from Boston Medical Center were randomized to a hypocaloric LFHC (n=26) or HFLC (n=29) diet for 12 weeks. The age range of subjects was 21-62 years. As a percentage of daily calories, the HFLC group consumed 33.5% protein, 56.0% fat and 9.6% carbohydrate and the LFHC group consumed 22.0% protein, 25.0% fat and 55.7% carbohydrate. The change in percent body weight, lean and fat mass, blood pressure, flow mediated dilation, hip:waist ratio, hemoglobin A1C, fasting insulin and glucose, and glucose and insulin response to a 2h oral glucose tolerance test did not differ (P>0.05) between diets after 12 weeks. The HFLC group had greater mean decreases in serum triglyceride (P=0.07), and hs-CRP (P=0.03), and greater mean increases in HDL cholesterol (P=0.004), and total adiponectin (P=0.045) relative to the LFHC. Secreted adipose tissue adiponectin or TNF-α did not differ after weight loss for either diet. Relative to the LFHC group, the HFLC group had greater improvements in blood lipids and systemic inflammation with similar changes in body weight and composition. This small-scale study suggests that HFLC diets may be more beneficial to cardiovascular health and inflammation in free-living obese adults compared to LFHC diets. © 2013.

  3. Placental Expression of Glucose Transporter Proteins in Pregnancies Complicated by Gestational and Pregestational Diabetes Mellitus.

    Science.gov (United States)

    Stanirowski, Paweł Jan; Szukiewicz, Dariusz; Pazura-Turowska, Monika; Sawicki, Włodzimierz; Cendrowski, Krzysztof

    2018-04-01

    Gestational diabetes mellitus and pregestational diabetes mellitus constitute carbohydrate metabolism disorders, which, if not diagnosed and adequately treated, lead to serious and often life-threatening pregnancy complications. According to a recently formulated hypothesis, some diabetes-related complications, such as fetal macrosomia, may be the result of disturbances in the transplacental transport of nutrients-in particular, excessive maternal-fetal glucose transfer. Throughout pregnancy, glucose flux across the placenta is mediated by the group of facilitative glucose transporters (GLUT), the expression of which in different placental compartments is the precondition for effective glucose uptake from maternal blood and its subsequent transfer to the fetal circulation. In diabetes-complicated pregnancies, the location, expression and activity of glucose transporters are modified to an extent that results in alterations in the maternal-fetal glucose exchange, potentially leading to an excessive supply of energy substrates to the fetus. This paper reviews the literature on the expression and activity of glucose transporter proteins-GLUT-1, GLUT-3, GLUT-4, GLUT-8, GLUT-9 and GLUT-12-in the human placenta, with a special focus on diabetes-complicated pregnancy. The characteristics of transporters in conditions of maternal normoglycemia and modifications occurring in the diabetic placenta are summarized, and the factors responsible for the regulation of the expression of selected isoforms are described. Finally, the impact of alterations in the placental expression of the aforementioned members of the GLUT family on intrauterine fetal development in pregnancies complicated by diabetes mellitus is discussed. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

  4. Comparative genomics of transport proteins in probiotic and pathogenic Escherichia coli and Salmonella enterica strains.

    Science.gov (United States)

    Do, Jimmy; Zafar, Hassan; Saier, Milton H

    2017-06-01

    Escherichia coli is a genetically diverse species that can be pathogenic, probiotic, commensal, or a harmless laboratory strain. Pathogenic strains of E. coli cause urinary tract infections, diarrhea, hemorrhagic colitis, and pyelonephritis, while the two known probiotic E. coli strains combat inflammatory bowel disease and play a role in immunomodulation. Salmonella enterica, a close relative of E. coli, includes two important pathogenic serovars, Typhi and Typhimurium, causing typhoid fever and enterocolitis in humans, respectively, with the latter strain also causing a lethal typhoid fever-like disease in mice. In this study, we identify the transport systems and their substrates within seven E. coli strains: two probiotic strains, two extracellular pathogens, two intracellular pathogens, and K-12, as well as the two intracellular pathogenic S. enterica strains noted above. Transport systems characteristic of each probiotic or pathogenic species were thus identified, and the tabulated results obtained with all of these strains were compared. We found that the probiotic and pathogenic strains generally contain more iron-siderophore and sugar transporters than E. coli K-12. Pathogens have increased numbers of pore-forming toxins, protein secretion systems, decarboxylation-driven Na + exporters, electron flow-driven monovalent cation exporters, and putative transporters of unknown function compared to the probiotic strains. Both pathogens and probiotic strains encode metabolite transporters that reflect their intracellular versus extracellular environments. The results indicate that the probiotic strains live extracellularly. It seems that relatively few virulence factors can convert a beneficial or commensal microorganism into a pathogen. Taken together, the results reveal the distinguishing features of these strains and provide a starting point for future engineering of beneficial enteric bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. The putative cellodextrin transporter-like protein CLP1 is involved in cellulase induction in Neurospora crassa.

    Science.gov (United States)

    Cai, Pengli; Wang, Bang; Ji, Jingxiao; Jiang, Yongsheng; Wan, Li; Tian, Chaoguang; Ma, Yanhe

    2015-01-09

    Neurospora crassa recently has become a novel system to investigate cellulase induction. Here, we discovered a novel membrane protein, cellodextrin transporter-like protein 1 (CLP1; NCU05853), a putative cellodextrin transporter-like protein that is a critical component of the cellulase induction pathway in N. crassa. Although CLP1 protein cannot transport cellodextrin, the suppression of cellulase induction by this protein was discovered on both cellobiose and Avicel. The co-disruption of the cellodextrin transporters cdt2 and clp1 in strain Δ3βG formed strain CPL7. With induction by cellobiose, cellulase production was enhanced 6.9-fold in CPL7 compared with Δ3βG. We also showed that the suppression of cellulase expression by CLP1 occurred by repressing the expression of cellodextrin transporters, particularly cdt1 expression. Transcriptome analysis of the hypercellulase-producing strain CPL7 showed that the cellulase expression machinery was dramatically stimulated, as were the cellulase enzyme genes including the inducer transporters and the major transcriptional regulators. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. The Putative Cellodextrin Transporter-like Protein CLP1 Is Involved in Cellulase Induction in Neurospora crassa*

    Science.gov (United States)

    Cai, Pengli; Wang, Bang; Ji, Jingxiao; Jiang, Yongsheng; Wan, Li; Tian, Chaoguang; Ma, Yanhe

    2015-01-01

    Neurospora crassa recently has become a novel system to investigate cellulase induction. Here, we discovered a novel membrane protein, cellodextrin transporter-like protein 1 (CLP1; NCU05853), a putative cellodextrin transporter-like protein that is a critical component of the cellulase induction pathway in N. crassa. Although CLP1 protein cannot transport cellodextrin, the suppression of cellulase induction by this protein was discovered on both cellobiose and Avicel. The co-disruption of the cellodextrin transporters cdt2 and clp1 in strain Δ3βG formed strain CPL7. With induction by cellobiose, cellulase production was enhanced 6.9-fold in CPL7 compared with Δ3βG. We also showed that the suppression of cellulase expression by CLP1 occurred by repressing the expression of cellodextrin transporters, particularly cdt1 expression. Transcriptome analysis of the hypercellulase-producing strain CPL7 showed that the cellulase expression machinery was dramatically stimulated, as were the cellulase enzyme genes including the inducer transporters and the major transcriptional regulators. PMID:25398875

  7. The Membrane Topology of ALMT1, an Aluminum-Activated Malate Transport Protein</