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Pedrini S, Chatterjee P, Hone E, Martins RN. High‐density lipoprotein‐related cholesterol metabolism in Alzheimer’s disease. J Neurochem 2020; 159:343-377. [DOI: 10.1111/jnc.15170] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Steve Pedrini
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
| | - Pratishtha Chatterjee
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
- Department of Biomedical Sciences Faculty of Medicine, Health and Human Sciences Macquarie University Sydney NSW Australia
| | - Eugene Hone
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
| | - Ralph N. Martins
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
- Department of Biomedical Sciences Faculty of Medicine, Health and Human Sciences Macquarie University Sydney NSW Australia
- School of Psychiatry and Clinical Neurosciences University of Western Australia Nedlands WA Australia
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2
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Kiron V, Kulkarni A, Dahle D, Vasanth G, Lokesh J, Elvebo O. Recognition of purified beta 1,3/1,6 glucan and molecular signalling in the intestine of Atlantic salmon. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 56:57-66. [PMID: 26615007 DOI: 10.1016/j.dci.2015.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 11/11/2015] [Accepted: 11/13/2015] [Indexed: 06/05/2023]
Abstract
Atlantic salmon was orally intubated with a highly purified β-glucan product (MacroGard(®)) to study the recognition of the molecule by the receptor genes, the regulation of the downstream signalling genes and global proteins, and the micromorphological changes in the intestine. The β-glucan receptor genes of Atlantic salmon, sclra, sclrb, sclrc and cr3, seem to recognize the molecule, and initiate the downstream ITAM-motif signalling, as evident from the significantly high mRNA levels of ksyk, mapkin2, il1b and mip2a levels. Among the altered proteins, the Apoa4 (involved in carbohydrate and lipid metabolism); Tagln, Actb (uptake of β-glucan); Psma2 (associated with substrate recognition); and Ckt (energy metabolism-related) were the overexpressed ones. The underexpressed proteins included the Uk114, Rpl9, Ctsb and Lgal that are connected to proliferation, LPS-stimulation, Il1b and lactose recognition, respectively. Furthermore, the mRNA levels of igt and the number of immune cells in the distal intestine were found to increase upon β-glucan uptake by the fish. This study provides some clues on the mechanisms by which the β-glucan evokes response in Atlantic salmon, particularly at the intestinal level.
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Affiliation(s)
- Viswanath Kiron
- Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway.
| | - Amod Kulkarni
- Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway.
| | - Dalia Dahle
- Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway.
| | - Ghana Vasanth
- Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway.
| | - Jep Lokesh
- Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway.
| | - Odd Elvebo
- Biorigin Europe NV, Vosseschijnstraat 59, Haven 182, BE 2030 Antwerpen, Belgium.
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3
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Rudkowska I, Vohl MC. Interaction between diets, polymorphisms and plasma lipid levels. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.10.26] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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4
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Lu S, Yao Y, Cheng X, Mitchell S, Leng S, Meng S, Gallagher JW, Shelness GS, Morris GS, Mahan J, Frase S, Mansbach CM, Weinberg RB, Black DD. Overexpression of apolipoprotein A-IV enhances lipid secretion in IPEC-1 cells by increasing chylomicron size. J Biol Chem 2005; 281:3473-83. [PMID: 16338933 DOI: 10.1074/jbc.m502501200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intestinal apolipoprotein A-IV expression is highly regulated by dietary lipid in newborn swine, suggesting a role in lipid absorption. Constitutive overexpression of apoA-IV in newborn swine enterocytes enhances basolateral secretion of triacylglycerol (TG) in TG-rich lipoproteins 4.9-fold (Lu, S., Yao, Y., Meng, S., Cheng, X., and Black, D. D. (2002) J. Biol. Chem. 277, 31929-31937). To investigate the mechanism of this enhancement, IPEC-1 cells were transfected with a tetracycline-regulatable expression system (Tet-On). In cells incubated with oleic acid, a dose response relationship was observed between medium doxycycline concentration and basolateral apoA-IV and TG secretion. Similarly regulated expression of apoA-I did not enhance lipid secretion. The mean diameter of TG-rich lipoproteins secreted from doxycycline-treated cells was larger than from untreated cells (87.0 nm versus 53.4 nm). Basolateral apoB secretion decreased. Using the same expression system, full-length human apoA-IV (376 amino acids); a "pig-like" human apoA-IV, lacking the C-terminal EQQQ repeats (361 amino acids); and a "chicken-like" apoA-IV, further truncated to 343 amino acids, were expressed in IPEC-1 cells. With increasing protein secretion, cells expressing the full-length human apoA-IV displayed a 2-fold increase in TG secretion; in sharp contrast, cells expressing the pig-like human apoA-IV displayed a 25-fold increase in TG secretion and a 27-fold increase in lipoprotein diameter. When human apoA-IV was further truncated to yield a chicken-like protein, TG secretion was inhibited. We conclude that overexpression of swine apoA-IV enhances basolateral TG secretion in a dose-dependent manner by increasing the size of secreted lipoproteins. These data suggest that the region in the human apoA-IV protein from residues 344 to 354 is critical to its ability to enhance lipid secretion, perhaps by enabling the packaging of additional core TG into chylomicron particles. The EQQQ-rich region may play an inhibitory or modulatory role in chylomicron packaging in humans.
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MESH Headings
- Amino Acid Sequence
- Animals
- Animals, Newborn
- Apolipoproteins/chemistry
- Apolipoproteins A/biosynthesis
- Apolipoproteins A/physiology
- Blotting, Western
- Cell Line
- Chickens
- Chylomicrons/chemistry
- Cloning, Molecular
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Doxycycline/metabolism
- Doxycycline/pharmacology
- Electrophoresis, Polyacrylamide Gel
- Humans
- Immunoprecipitation
- Intestinal Mucosa/metabolism
- Intestines/cytology
- Lipid Metabolism
- Lipids/chemistry
- Lipoproteins/metabolism
- Microscopy, Electron
- Microscopy, Electron, Transmission
- Molecular Sequence Data
- Mutation
- Oleic Acid/chemistry
- Oleic Acid/metabolism
- Protein Structure, Tertiary
- RNA/metabolism
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Swine
- Tetracycline/pharmacology
- Transcriptional Activation
- Triglycerides/metabolism
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Affiliation(s)
- Song Lu
- Children's Foundation Research Center at Le Bonheur Children's Medical Center and Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee 38103, USA
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5
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Abstract
Nutritional genomics has tremendous potential to change the future of dietary guidelines and personal recommendations. Nutrigenetics will provide the basis for personalized dietary recommendations based on the individual's genetic make up. This approach has been used for decades for certain monogenic diseases; however, the challenge is to implement a similar concept for common multifactorial disorders and to develop tools to detect genetic predisposition and to prevent common disorders decades before their manifestation. The preliminary results involving gene-diet interactions for cardiovascular diseases and cancer are promising, but mostly inconclusive. Success in this area will require the integration of different disciplines and investigators working on large population studies designed to adequately investigate gene-environment interactions. Despite the current difficulties, preliminary evidence strongly suggests that the concept should work and that we will be able to harness the information contained in our genomes to achieve successful aging using behavioral changes; nutrition will be the cornerstone of this endeavor.
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Affiliation(s)
- Jose M Ordovas
- Nutrition and Genomics Laboratory, Jean Mayer-U.S. Department of Agriculture, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA.
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6
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Abstract
Under optimal conditions, plasma cholesterol homeostasis is maintained by a variety of mechanisms, balancing input and output, thereby preventing the net accumulation of cholesterol in circulation and tissues. Among these mechanisms, intestinal cholesterol absorption has recently re-emerged as a potentially important contributor to cholesterol homeostasis. However, its regulation has been difficult to study in humans because of technical limitations in methodologies. In this review the major methods available for measuring cholesterol absorption including those that utilize cholesterol balance, single dose isotopic feeding, dual isotope plasma ratio, continuous isotope feeding, intestinal perfusion, stable isotopes and serum plant sterols or cholestanol to cholesterol ratios are reviewed and contrasted. Emphasis is placed on the strengths, technical and interpretational limitations and their applicability for use in metabolic, small-scale outpatient, population and large-scale intervention studies.
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Affiliation(s)
- Nirupa R Matthan
- Cardiovascular Nutrition Laboratory, Jean Mayer US DA Human Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA 02111, USA.
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7
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Gallagher JW, Weinberg RB, Shelness GS. apoA-IV tagged with the ER retention signal KDEL perturbs the intracellular trafficking and secretion of apoB. J Lipid Res 2004; 45:1826-34. [PMID: 15258202 DOI: 10.1194/jlr.m400188-jlr200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To examine the role of apolipoprotein A-IV (apoA-IV) in the intracellular trafficking and secretion of apoB, COS cells were cotransfected with microsomal triglyceride transfer protein (MTP), apoB-41 (amino terminal 41% of apoB), and either native apoA-IV or apoA-IV modified with the carboxy-terminal endoplasmic reticulum (ER) retention signal, KDEL (apoA-IV-KDEL). As expected, apoA-IV-KDEL was inefficiently secreted relative to native apoA-IV. Coexpression of apoB-41 with apoA-IV-KDEL reduced the secretion of apoB-41 by approximately 80%. The apoA-IV-KDEL effect was specific, as neither KDEL-modified forms of human serum albumin or apoA-I affected apoB-41 secretion. Similar results were observed in McA-RH7777 rat hepatoma cells, which express endogenous MTP. The full inhibitory effect of apoA-IV-KDEL on apoB secretion was observed only for forms of apoB containing a minimum of the amino-terminal 25% of the protein (apoB-25). However, apoA-IV-KDEL inhibited the secretion of both lipid-associated and lipid-poor forms of apoB-25. Dual-label immunofluorescence microscopy of cells transfected with native apoA-IV and apoB-25 revealed that both apolipoproteins were localized to the ER and Golgi, as expected. However, when apoA-IV-KDEL was cotransfected with apoB-25, both proteins localized primarily to the ER. These data suggest that apoA-IV may physically interact with apoB in the secretory pathway, perhaps reflecting a role in modulating the process of triglyceride-rich lipoprotein assembly and secretion.
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Affiliation(s)
- James W Gallagher
- Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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8
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Masson LF, McNeill G, Avenell A. Genetic variation and the lipid response to dietary intervention: a systematic review. Am J Clin Nutr 2003; 77:1098-111. [PMID: 12716659 DOI: 10.1093/ajcn/77.5.1098] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
There is wide interindividual variation in the lipid and lipoprotein responses to dietary change, and the existence of consistent hypo- and hyperresponders supports the hypothesis that responsiveness is related to genetic variation. Many studies have investigated the possibility that the heterogeneity in responsiveness to changes in dietary fat, cholesterol, and fiber intake is explained by variation in genes whose products affect lipoprotein metabolism, eg, apolipoproteins, enzymes, and receptors. A systematic review of the literature was carried out to investigate the effect of genetic variation on the lipid response to dietary intervention. A search strategy for the MEDLINE database retrieved 2540 articles from 1966 to February 2002. This strategy was adapted and performed on the EMBASE database, which retrieved 2473 articles from 1980 to week 9, 2002. Reference lists from relevant journal articles were also checked. This is the first systematic review of the literature, and it summarizes results available from 74 relevant articles. There is evidence to suggest that variation in the genes for apolipoprotein (apo) A-I, apo A-IV, apo B, and apo E contributes to the heterogeneity in the lipid response to dietary intervention. However, the effects of genetic variation are not consistently seen and are sometimes conflicting. Future studies need to have much larger sample sizes based on power calculations and carefully controlled dietary interventions and should investigate the effects of polymorphisms in multiple genes instead of the effects of polymorphisms in single genes.
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Affiliation(s)
- Lindsey F Masson
- Department of Public Health, University of Aberdeen, Aberdeen, United Kingdom.
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9
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Stan S, Delvin E, Lambert M, Seidman E, Levy E. Apo A-IV: an update on regulation and physiologic functions. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1631:177-87. [PMID: 12633684 DOI: 10.1016/s1388-1981(03)00004-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Apolipoprotein (apo) A-IV, first identified 28 years ago as a plasma lipoprotein moiety, is now known to participate in the regulation of various metabolic pathways. It is synthesized primarily in the enterocytes of the small intestine during fat absorption. After entry into the bloodstream, the 46-kDa glycoprotein apo A-IV appears associated with chylomicrons, high-density lipoproteins, and in the lipoprotein-free fraction. It has a role in lipid absorption, transport and metabolism, and may act as a post-prandial satiety signal, an anti-oxidant and a major factor in the prevention of atherosclerosis. After summarizing and discussing these functions for reader's comprehension, the current review focuses on the regulation of apo A-IV by nutrients, biliary components, drugs, hormones and gastrointestinal peptides. The understanding of the involved mechanisms that underline apo A-IV regulation may in the long run allow us to switch on its gene, which may confer multiple beneficial effects, including the protection from atherosclerosis.
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Affiliation(s)
- Simona Stan
- Research Center, Hôpital Sainte-Justine, Université de Montréal, Montréal, Québec, Canada H3T 1C5
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10
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Vincent S, Planells R, Defoort C, Bernard MC, Gerber M, Prudhomme J, Vague P, Lairon D. Genetic polymorphisms and lipoprotein responses to diets. Proc Nutr Soc 2002; 61:427-34. [PMID: 12691171 DOI: 10.1079/pns2002177] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
While human diets have markedly evolved since their origin, the human genome has only marginally changed. Nevertheless, polymorphisms of common genes are widespread. It has been substantiated that most major diseases (including cardiovascular disease, diabetes, obesity and cancers) result from the interaction between genetic susceptibility and environmental factors, including diet. In the field of lipoprotein metabolism and cardiovascular disease several gene polymorphisms for key proteins, such as apoproteins (apo) E, B, A-IV and C-III, LDL receptor, microsomal transfer protein (MTP), fatty acid-binding protein (FABP), cholesteryl ester transfer protein (CETP), lipoprotein lipase and hepatic lipase, have been identified and linked to variable responses to diets. We are carrying out an intervention study (RIVAGE) in Marseille dedicated to investigating the interactions between diets (Mediterranean or low-fat types v. standard Western type), risk factors for cardiovascular disease and gene polymorphisms in about 300 patients randomized into two groups over periods of 3 and 12 months. Some data obtained in about 100 patients after 3 months of dietary change are available. Among single nucleotide polymorphisms (SNP) already studied (apoE (epsilon2, epsilon3, epsilon4), apoB (-516C/T), apoC-III (SstI), apoA-IV (Ser347Thr), MTP (-493G/T), intestinal FABP (Ala54Thr), CETP (TaqIB) and hepatic lipase (-480C/T)), some SNP showed interactions with diets in relation to changes in particular variables after 3 months on the dietary regimens. This was the case for apoE and LDL-cholesterol and triacylglycerols, apoA-IV and LDL-cholesterol, MTP and LDL-cholesterol, intestinal FABP and triacylglycerols. These data provide evidence of the interaction between some SNP and the metabolic response to diets.
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Affiliation(s)
- Stephanie Vincent
- Unité 476-Human Nutrition and Lipids at INSERM (National Institute of Health and Medical Research), 18 Avenue Mozart, 13009 Marseille, France
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11
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Lu S, Yao Y, Meng S, Cheng X, Black DD. Overexpression of apolipoprotein A-IV enhances lipid transport in newborn swine intestinal epithelial cells. J Biol Chem 2002; 277:31929-37. [PMID: 12070145 DOI: 10.1074/jbc.m201418200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein A-IV (apoA-IV) has myriad functions, including roles as a post-prandial satiety factor and lipid antioxidant. ApoA-IV is expressed in mammalian small intestine and is up-regulated in response to lipid absorption. In newborn swine jejunum, a high fat diet acutely induces a 7-fold increase in apoA-IV expression. To determine whether apoA-IV plays a role in the transport of absorbed lipid, swine apoA-IV was overexpressed in a newborn swine enterocyte cell line, IPEC-1, followed by analysis of the expression of genes related to lipoprotein assembly and lipid transport, as well as quantitation of lipid synthesis and secretion. A full-length swine apoA-IV cDNA was cloned, sequenced, and inserted into a Vp and Rep gene-deficient adeno-associated viral vector, containing the cytomegalovirus immediate early promoter/enhancer and neomycin resistance gene, and was used to transfect IPEC-1 cells. Control cells were transfected with the same vector minus the apoA-IV insert. Using neomycin selection, apoA-IV-overexpressing (+AIV) and control (-AIV) clones were isolated for further study. Both undifferentiated (-D) and differentiated (+D) +AIV cells expressed 40- to 50-fold higher levels of apoA-IV mRNA and both intracellular and secreted apoA-IV protein compared with -AIV cells. Expression of other genes was not affected by apoA-IV overexpression in a manner that would contribute to enhanced lipid secretion. +D +AIV cells secreted 4.9-fold more labeled triacylglycerol (TG), 4.6-fold more labeled cholesteryl ester (CE), and 2-fold more labeled phospholipid (PL) as lipoproteins, mostly in the chylomicron/very low density lipoprotein (VLDL) density range. ApoA-IV overexpression in IPEC-1 cells enhances basolateral TG, CE, and PL secretion in chylomicron/VLDL particles. This enhancement is not associated with up-regulation of other genes involved in lipid transport. ApoA-IV may play a role in facilitating enterocyte lipid transport, particularly in the neonate receiving a diet of high fat breast milk.
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Affiliation(s)
- Song Lu
- Children's Foundation Research Center at Le Bonheur Children's Medical Center, University of Tennessee Health Science Center, Memphis, Tennessee 38103, USA
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12
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Abstract
Apolipoprotein A-IV is a 46kDa glycoprotein that is synthesized by intestinal enterocytes and is incorporated into the surface of nascent chylomicrons. Considerable evidence suggests that apolipoprotein A-IV plays a role in intestinal lipid absorption and chylomicron assembly. We have proposed that polymorphisms that alter the interfacial behavior of apolipoprotein A-IV may modulate the physical properties and metabolic fate of plasma chylomicrons. Of the reported genetic polymorphisms of apolipoprotein A-IV, two, Q360H and T347S, are known to occur at high frequencies among the world populations. Biophysical studies have established that the Q360H isoprotein displays higher lipid affinity; conversely the T347S isoprotein is predicted to be less lipid avid. Recent studies have shown that the Q360H polymorphism is associated with increased postprandial hypertriglyceridemia, a reduced low-density lipoprotein response to dietary cholesterol in the setting of a moderate fat intake, an increased high-density lipoprotein response to changes in total dietary fat content, and lower body mass and adiposity; the T347S polymorphism appears to confer the opposite effects. Studies on the diet-gene interactions of other apolipoprotein A-IV alleles are needed, as are studies on the interactions between apolipoprotein A-IV alleles and other apolipoprotein polymorphisms.
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Affiliation(s)
- Richard B Weinberg
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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13
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Abstract
Cholesterol absorption is a key regulatory point in human lipid metabolism because it determines the amount of endogenous biliary as well as dietary cholesterol that is retained, thereby influencing whole body cholesterol balance. Plant sterols (phytosterols) and the drug ezetimibe reduce cholesterol absorption and low-density lipoprotein cholesterol in clinical trials, complementing the statin drugs, which inhibit cholesterol biosynthesis. The mechanism of cholesterol absorption is not completely known but involves the genes ABC1, ABCG5, and ABCG8, which are members of the ATP-binding cassette protein family and appear to remove unwanted cholesterol and phytosterols from the enterocyte. ABC1 is upregulated by the liver X (LXR) and retinoid X (RXR) nuclear receptors. Acylcholesterol acytransferase-2 is an intestinal enzyme that esterifies absorbed cholesterol and increases cholesterol absorption when dietary intake is high. New clinical treatments based on better understanding of absorption physiology are likely to substantially improve clinical cholesterol management in the future.
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Affiliation(s)
- Richard E Ostlund
- Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, Washington University, St. Louis, Missouri 63110, USA.
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Hockey KJ, Anderson RA, Cook VR, Hantgan RR, Weinberg RB. Effect of the apolipoprotein A-IV Q360H polymorphism on postprandial plasma triglyceride clearance. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)31681-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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15
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Gremaud G, Piguet C, Baumgartner M, Pouteau E, Decarli B, Berger A, Fay LB. Simultaneous assessment of cholesterol absorption and synthesis in humans using on-line gas chromatography/ combustion and gas chromatography/pyrolysis/isotope-ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2001; 15:1207-1213. [PMID: 11445904 DOI: 10.1002/rcm.365] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A number of dietary components and drugs are known to inhibit the absorption of dietary and biliary cholesterol, but at the same time can compensate by increasing cholesterol synthesis. It is, therefore, necessary to have a convenient and accurate method to assess both parameters simultaneously. Hence, we validated such a method in humans using on-line gas chromatography(GC)/combustion and GC/pyrolysis/isotope-ratio mass spectrometry (IRMS). Cholesterol absorption was measured using the ratio of [(13)C]cholesterol (injected intravenously) to [(18)O]cholesterol (administered orally). Simultaneously, cholesterol synthesis was measured using the deuterium incorporation method. Our methodology was applied to 12 mildly hypercholesterolemic men that were given a diet providing 2685 +/- 178 Kcal/day (mean +/- SD) and 255 +/- 8 mg cholesterol per day. Cholesterol fractional synthesis rates ranged from 5.0 to 10.5% pool/day and averaged 7.36% +/- 1.78% pool/day (668 +/- 133 mg/day). Cholesterol absorption ranged from 36.5-79.9% with an average value of 50.8 +/- 15.4%. These values are in agreement with already known data obtained with mildly hypercholesterolemic Caucasian males placed on a diet similar to the one used for this study. However, our combined IRMS method has the advantage over existing methods that it enables simultaneous measurement of cholesterol absorption and synthesis in humans, and is therefore an important research tool for studying the impact of dietary treatments on cholesterol parameters.
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Affiliation(s)
- G Gremaud
- Nestlé Research Center, Nestec Ltd, Vers-chez-les-Blanc, P.O. Box 44, 1000 Lausanne 26, Switzerland
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