51
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Magnolo L, Najah M, Fancello T, Di Leo E, Pinotti E, Brini I, Gueddiche NM, Calandra S, Slimene NM, Tarugi P. Novel mutations in SAR1B and MTTP genes in Tunisian children with chylomicron retention disease and abetalipoproteinemia. Gene 2013; 512:28-34. [DOI: 10.1016/j.gene.2012.09.117] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 09/29/2012] [Indexed: 10/27/2022]
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52
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Jiang ZG, Robson SC, Yao Z. Lipoprotein metabolism in nonalcoholic fatty liver disease. J Biomed Res 2012; 27:1-13. [PMID: 23554788 PMCID: PMC3596749 DOI: 10.7555/jbr.27.20120077] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 08/23/2012] [Accepted: 08/29/2012] [Indexed: 12/18/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD), an escalating health problem worldwide, covers a spectrum of pathologies characterized by fatty accumulation in hepatocytes in early stages, with potential progression to liver inflammation, fibrosis, and failure. A close, yet poorly understood link exists between NAFLD and dyslipidemia, a constellation of abnormalities in plasma lipoproteins including triglyceride-rich very low density lipoproteins. Apolipoproteins are a group of primarily liver-derived proteins found in serum lipoproteins; they not only play an extracellular role in lipid transport between vital organs through circulation, but also play an important intracellular role in hepatic lipoprotein assembly and secretion. The liver functions as the central hub for lipoprotein metabolism, as it dictates lipoprotein production and to a significant extent modulates lipoprotein clearance. Lipoprotein metabolism is an integral component of hepatocellular lipid homeostasis and is implicated in the pathogenesis, potential diagnosis, and treatment of NAFLD.
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Affiliation(s)
- Zhenghui Gordon Jiang
- Department of Medicine, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA, USA
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53
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Abstract
Intestinal lipid transport plays a central role in fat homeostasis. Here we review the pathways regulating intestinal absorption and delivery of dietary and biliary lipid substrates, principally long-chain fatty acid, cholesterol, and other sterols. We discuss the regulation and functions of CD36 in fatty acid absorption, NPC1L1 in cholesterol absorption, as well as other lipid transporters including FATP4 and SRB1. We discuss the pathways of intestinal sterol efflux via ABCG5/G8 and ABCA1 as well as the role of the small intestine in high-density lipoprotein (HDL) biogenesis and reverse cholesterol transport. We review the pathways and genetic regulation of chylomicron assembly, the role of dominant restriction points such as microsomal triglyceride transfer protein and apolipoprotein B, and the role of CD36, l-FABP, and other proteins in formation of the prechylomicron complex. We will summarize current concepts of regulated lipoprotein secretion (including HDL and chylomicron pathways) and include lessons learned from families with genetic mutations in dominant pathways (i.e., abetalipoproteinemia, chylomicron retention disease, and familial hypobetalipoproteinemia). Finally, we will provide an integrative view of intestinal lipid homeostasis through recent findings on the role of lipid flux and fatty acid signaling via diverse receptor pathways in regulating absorption and production of satiety factors.
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Affiliation(s)
- Nada A Abumrad
- Center for Human Nutrition and Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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54
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Turk U, Basol G, Barutcuoglu B, Sahin F, Habif S, Tarugi P, Bayindir O. A 54-Year-Old Diabetic Man with Low Serum Cholesterol. Clin Chem 2012; 58:826-9. [DOI: 10.1373/clinchem.2011.163543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ugur Turk
- Department of Cardiology, Central Hospital, Izmir, Turkey
| | | | | | - Fahri Sahin
- Hematology, Ege University Faculty of Medicine, Izmir, Turkey
| | - Sara Habif
- Departments of Clinical Biochemistry and
| | - Patrizia Tarugi
- Department of Biomedical Sciences, University of Modena e Reggio Emilia, Modena, Italy
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55
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Congenital diarrheal disorders: an updated diagnostic approach. Int J Mol Sci 2012; 13:4168-4185. [PMID: 22605972 PMCID: PMC3344208 DOI: 10.3390/ijms13044168] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 03/02/2012] [Accepted: 03/19/2012] [Indexed: 01/07/2023] Open
Abstract
Congenital diarrheal disorders (CDDs) are a group of inherited enteropathies with a typical onset early in the life. Infants with these disorders have frequently chronic diarrhea of sufficient severity to require parenteral nutrition. For most CDDs the disease-gene is known and molecular analysis may contribute to an unequivocal diagnosis. We review CDDs on the basis of the genetic defect, focusing on the significant contribution of molecular analysis in the complex, multistep diagnostic work-up.
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Identification of a novel mutation in the ANGPTL3 gene in two families diagnosed of familial hypobetalipoproteinemia without APOB mutation. Clin Chim Acta 2012; 413:552-5. [DOI: 10.1016/j.cca.2011.11.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 10/17/2011] [Accepted: 11/20/2011] [Indexed: 11/17/2022]
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57
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Hentati F, El-Euch G, Bouhlal Y, Amouri R. Ataxia with vitamin E deficiency and abetalipoproteinemia. HANDBOOK OF CLINICAL NEUROLOGY 2011; 103:295-305. [PMID: 21827896 DOI: 10.1016/b978-0-444-51892-7.00018-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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58
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Crook MA. A place for assaying serum apolipoprotein AI and B? Ann Clin Biochem 2011; 48:485-6. [DOI: 10.1258/acb.2011.011205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- M A Crook
- Department of Clinical Biochemistry and Metabolic Medicine, University Hospital Lewisham, London SE13 6LH; Department of Chemical Pathology and Metabolic Medicine, Guy's and St Thomas' Hospitals, London; Faculty of Science, University of Greenwich, London SE10 9LS, UK
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59
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Gangloff A, Bergeron J, Couture P, Martins R, Hegele RA, Gagné C. A novel mutation of apolipoprotein B in a French Canadian family with homozygous hypobetalipoproteinemia. J Clin Lipidol 2011; 5:414-7. [DOI: 10.1016/j.jacl.2011.06.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 06/01/2011] [Accepted: 06/21/2011] [Indexed: 11/15/2022]
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Guan M, Qu L, Tan W, Chen L, Wong CW. Hepatocyte nuclear factor-4 alpha regulates liver triglyceride metabolism in part through secreted phospholipase A₂ GXIIB. Hepatology 2011; 53:458-66. [PMID: 21274867 DOI: 10.1002/hep.24066] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 10/27/2010] [Indexed: 12/07/2022]
Abstract
UNLABELLED Hepatocyte nuclear factor-4 alpha (HNF-4α) is an important transcription factor governing the expression of genes involved in multiple metabolic pathways. Secreted phospholipase A(2) GXIIB (PLA(2) GXIIB) is an atypical member of a class of secreted phospholipases A(2) . We establish in this study that PLA(2) GXIIB is an HNF-4α target gene. We demonstrate that HNF-4α binds to a response element on the PLA(2) GXIIB promoter. Moreover, HNF-4α agonists induce PLA(2) GXIIB expression in human hepatocarcinoma cells. Importantly, PLA(2) GXIIB-null mice accumulate triglyceride, cholesterol, and fatty acids in the liver and develop severe hepatosteatosis resembling some of the phenotypes of liver-specific HNF-4α-null mice. These defects are in part due to compromised hepatic very low-density lipoprotein secretion. Finally, adenovirus-mediated overexpression of HNF-4α elevates serum triglyceride level in wild-type but not PLA(2) GXIIB-null mice. CONCLUSION Collectively, these evidences suggest that HNF-4α is a key physiological PLA(2) GXIIB transcriptional regulator and that PLA(2) GXIIB is a novel mediator of triglyceride metabolism in the liver.
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Affiliation(s)
- Min Guan
- Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou Science City, China
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61
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62
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Hoofnagle AN, Heinecke JW. Lipoproteomics: using mass spectrometry-based proteomics to explore the assembly, structure, and function of lipoproteins. J Lipid Res 2010; 50:1967-75. [PMID: 19738003 DOI: 10.1194/jlr.r900015-jlr200] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Lipoproteins are centrally important in lipid transport, fuel metabolism, and cardiovascular disease. The prototypic lipoprotein has an outer shell of amphipathic lipids and proteins that solubilizes a hydrophobic lipid core. Lipoprotein-associated proteins have classically been viewed as structural elements and factors important in lipid metabolism. Recent mass spectrometric analyses reveal that the protein cargo of lipoproteins is much more diverse than previously appreciated, raising the possibility that lipoproteins play previously unsuspected roles in host defense mechanisms and inflammation. They further suggest that lipoprotein-associated proteins can identify humans at increased risk of cardiovascular disease. Here, we summarize recent developments in lipoproteomics, the proteomic analysis of lipoproteins. We also discuss the promises and challenges this powerful analytical strategy offers for expanding our understanding of the biology and structures of lipoproteins.
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Affiliation(s)
- Andrew N Hoofnagle
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA.
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63
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Clinical Implications of Lipid Genetics for Cardiovascular Disease. CURRENT CARDIOVASCULAR RISK REPORTS 2010; 4:461-468. [PMID: 21853159 DOI: 10.1007/s12170-010-0131-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Cardiovascular disease is the leading cause of morbidity and mortality in the developed world. Epidemiologic data support a strong relationship of atherosclerotic cardiovascular disease (ASCVD) with both elevated low-density lipoprotein cholesterol (LDL-C), and reduced high-density lipoprotein cholesterol (HDL-C). The study of the human genetics of plasma lipid traits, both rare Mendelian disorders as well as common variants, has illuminated multiple genes and pathways involved in the regulation of LDL-C and HDL-C levels. Mendelian disorders of extremes of LDL-C and Mendelian randomization studies of common gene variants associated with LDL-C strongly support a causal relationship between LDL-C and ASCVD, independent of mechanism. In contrast, Mendelian disorders of extremes of HDL-C and Mendelian randomization studies of common genetic variants for HDL-C are inconsistent in their support of a causal relationship between HDL-C and ASCVD. In contrast to LDL-C, a causal relationship between HDL-C and ASCVD may be dependent on the specific mechanism leading to variation in HDL-C levels.
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64
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Srivastava N, Cefalu A, Noto D, Schonfeld G, Averna M, Srivastava RAK. The production of 85kDa N-terminal fragment of apolipoprotein B in mutant HepG2 cells generated by targeted modification of apob gene occurs by ALLN-inhibitable protease cleavage during translocation. Biochem Biophys Res Commun 2010; 398:665-70. [DOI: 10.1016/j.bbrc.2010.06.130] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Accepted: 06/30/2010] [Indexed: 10/19/2022]
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65
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Chen Z, Norris JY, Finck BN. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) stimulates VLDL assembly through activation of cell death-inducing DFFA-like effector B (CideB). J Biol Chem 2010; 285:25996-6004. [PMID: 20551328 DOI: 10.1074/jbc.m110.141598] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Abnormalities in very low density lipoprotein (VLDL) assembly and secretion impact intrahepatic lipid homeostasis, plasma lipoprotein profile, and energy metabolism of distal peripheral tissues. We have evaluated the role of the transcriptional coactivator, the peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), in VLDL assembly and secretion. PGC-1alpha overexpression in HepG2 cells led to diminished rates of triglyceride (TG) synthesis but strongly stimulated VLDL-TG secretion, markedly increasing the efficiency of secretion of newly synthesized TG. PGC-1alpha overexpression increased the rate of secretion of apoB100 and promoted secretion of larger, less dense VLDL particles. PGC-1alpha overexpression in intact mouse liver also stimulated rates of VLDL TG secretion and attenuated hepatic TG accumulation resulting from high fat diet feeding. To determine the molecular mechanisms mediating the effect of PGC-1alpha on VLDL assembly, we evaluated the expression of several candidate mediators known to be involved in VLDL assembly or hepatic lipid homeostasis. Cell death-inducing DFFA-like effector B (CideB) expression was greatly induced by PGC-1alpha, and siRNA against CideB reversed the effects of PGC-1alpha on the secretion of TG and VLDL-sized particles by HepG2 cells, indicating that CideB is a critical mediator of stimulatory effects of PGC-1alpha on VLDL secretion. Collectively, these data suggest that PGC-1alpha plays an important role in partitioning cytoplasmic TG toward the VLDL secretory compartments and promoting VLDL secretion via transcriptional induction of CideB.
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Affiliation(s)
- Zhouji Chen
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA.
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66
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Sundaram M, Yao Z. Recent progress in understanding protein and lipid factors affecting hepatic VLDL assembly and secretion. Nutr Metab (Lond) 2010; 7:35. [PMID: 20423497 PMCID: PMC2873297 DOI: 10.1186/1743-7075-7-35] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 04/27/2010] [Indexed: 02/06/2023] Open
Abstract
Excess lipid induced metabolic disorders are one of the major existing challenges for the society. Among many different causes of lipid disorders, overproduction and compromised catabolism of triacylglycerol-rich very low density lipoproteins (VLDL) have become increasingly prevalent leading to hyperlipidemia worldwide. This review provides the latest understanding in different aspects of VLDL assembly process, including structure-function relationships within apoB, mutations in APOB causing hypobetalipoproteinemia, significance of modulating microsomal triglyceride-transfer protein activity in VLDL assembly, alterations of VLDL assembly by different fatty acid species, and hepatic proteins involved in vesicular trafficking, and cytosolic lipid droplet metabolism that contribute to VLDL assembly. The role of lipoprotein receptors and exchangeable apolipoproteins that promote or diminish VLDL assembly and secretion is discussed. New understanding on dysregulated insulin signaling as a consequence of excessive triacylglycerol-rich VLDL in the plasma is also presented. It is hoped that a comprehensive view of protein and lipid factors that contribute to molecular and cellular events associated with VLDL assembly and secretion will assist in the identification of pharmaceutical targets to reduce disease complications related to hyperlipidemia.
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Affiliation(s)
- Meenakshi Sundaram
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada
| | - Zemin Yao
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada
- Department of Pathology and Laboratory Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada
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67
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Affiliation(s)
- R Dermot G Neely
- Clinical Biochemistry Department, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK.
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68
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Abstract
Posttranscriptional regulation of gene expression is increasingly recognized as a model for inherited and acquired disease. Recent work has expanded understanding of the range of mechanisms that regulate several of these distinct steps, including messenger RNA (mRNA) splicing, trafficking, and/or stability. Each of these pathways is implicated in disease pathogenesis, and each represents important avenues for therapeutic intervention. This review summarizes important mechanisms controlling mRNA processing and the regulation of mRNA degradation, including the role of microRNAs and RNA binding proteins. These pathways provide important opportunities for therapeutic targeting directed at splicing and degradation in order to attenuate genetic defects in RNA metabolism. We will highlight developments in vector development and validation for therapeutic manipulation of mRNA expression with a focus on potential applications in metabolic and immunomediated liver disease.
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Affiliation(s)
| | - Nicholas O. Davidson
- Contact information: Nicholas O. Davidson, MD, Division of Gastroenterology, Box 8124, Washington University School of Medicine, 660. Euclid Avenue, St. Louis, MO 63110, Phone: (314)-362-2027,
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69
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Novel Mutation in the Apob Gene (Apo B-15.56): A Case Report. Balkan J Med Genet 2010. [DOI: 10.2478/v10034-010-0029-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Novel Mutation in theApobGene (Apo B-15.56): A Case ReportFamilial hypobetalipoproteinemia (FHBL) is a rare co-dominant genetic disorder characterized by decrease of plasma low density lipoprotein-cholesterol (LDL-c) or apolipoprotein B (Apo-B) equal to or less than the 5thpercentile for the population. We describe a 48-year-old male who presented with fatty liver disease (FLD), insulin resistance (IR), obesity and hypertension. Our patient thus met the latest diagnostic criteria of the metabolic syndrome (MS) proposed by the Adult Treatment Panel and the International Diabetes Federation. However, he had very low plasma concentration of LDL-c and Apo-B. DNA sequencing showed that he and two first-degree relatives affected by obesity and mild IR were heterozygous for a single nucleotide deletion on exon 15 of theAPOBgene, which was predicted to form a truncated Apo-B designated Apo B-15.56.
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70
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Zhong S, Magnolo AL, Sundaram M, Zhou H, Yao EF, Di Leo E, Loria P, Wang S, Bamji-Mirza M, Wang L, McKnight CJ, Figeys D, Wang Y, Tarugi P, Yao Z. Nonsynonymous mutations within APOB in human familial hypobetalipoproteinemia: evidence for feedback inhibition of lipogenesis and postendoplasmic reticulum degradation of apolipoprotein B. J Biol Chem 2009; 285:6453-64. [PMID: 20032471 DOI: 10.1074/jbc.m109.060467] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Five nontruncating missense APOB mutations, namely A31P, G275S, L324M, G912D, and G945S, were identified in heterozygous carriers of familial hypobetalipoproteinemia (FHBL) in the Italian population. To test that the FHBL phenotype was a result of impaired hepatic secretion of mutant apoB proteins, we performed transfection studies using McA-RH7777 cells stably expressing wild type or mutant forms of human apolipoprotein B-48 (apoB-48). All mutant proteins displayed varied impairment in secretion, with G912D the least affected and A31P barely secreted. Although some A31P was degraded by proteasomes, a significant proportion of it (although inappropriately glycosylated) escaped endoplasmic reticulum (ER) quality control and presented in the Golgi compartment. Degradation of the post-ER A31P was achieved by autophagy. Expression of A31P also decreased secretion of endogenous apoB and triglycerides, yet the impaired lipoprotein secretion did not lead to lipid accumulation in the cells or ER stress. Rather, expression of genes involved in lipogenesis was down-regulated, including liver X receptor alpha, sterol regulator element-binding protein 1c, fatty acid synthase, acetyl-CoA carboxylase 1, stearoyl-CoA desaturase 1, and lipin-1. These results suggest that feedback inhibition of hepatic lipogenesis in conjunction with post-ER degradation of misfolded apoB proteins can contribute to reduce fat accumulation in the FHBL liver.
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Affiliation(s)
- Shumei Zhong
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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71
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Curcio CA, Johnson M, Huang JD, Rudolf M. Aging, age-related macular degeneration, and the response-to-retention of apolipoprotein B-containing lipoproteins. Prog Retin Eye Res 2009; 28:393-422. [PMID: 19698799 PMCID: PMC4319375 DOI: 10.1016/j.preteyeres.2009.08.001] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The largest risk factor for age-related macular degeneration (ARMD) is advanced age. A prominent age-related change in the human retina is the accumulation of histochemically detectable neutral lipid in normal Bruch's membrane (BrM) throughout adulthood. This change has the potential to have a major impact on physiology of the retinal pigment epithelium (RPE). It occurs in the same compartment as drusen and basal linear deposit, the pathognomonic extracellular, lipid-containing lesions of ARMD. Here we present evidence from light microscopic histochemistry, ultrastructure, lipid profiling of tissues and isolated lipoproteins, and gene expression analysis that this deposition can be accounted for by esterified cholesterol-rich, apolipoprotein B-containing lipoprotein particles constitutively produced by the RPE. This work collectively allows ARMD lesion formation and its aftermath to be conceptualized as a response to the retention of a sub-endothelial apolipoprotein B lipoprotein, similar to a widely accepted model of atherosclerotic coronary artery disease (CAD) (Tabas et al., 2007). This approach provides a wide knowledge base and sophisticated clinical armamentarium that can be readily exploited for the development of new model systems and the future benefit of ARMD patients.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL 35294-0009, USA.
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72
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Curcio CA, Johnson M, Huang JD, Rudolf M. Apolipoprotein B-containing lipoproteins in retinal aging and age-related macular degeneration. J Lipid Res 2009; 51:451-67. [PMID: 19797256 DOI: 10.1194/jlr.r002238] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The largest risk factor for age-related macular degeneration (ARMD) is advanced age. With aging, there is a striking accumulation of neutral lipids in Bruch's membrane (BrM) of normal eye that continues through adulthood. This accumulation has the potential to significantly impact the physiology of the retinal pigment epithelium (RPE). It also ultimately leads to the creation of a lipid wall at the same locations where drusen and basal linear deposit, the pathognomonic extracellular, lipid-containing lesions of ARMD, subsequently form. Here, we summarize evidence obtained from light microscopy, ultrastructural studies, lipid histochemistry, assay of isolated lipoproteins, and gene expression analysis. These studies suggest that lipid deposition in BrM is at least partially due to accumulation of esterified cholesterol-rich, apolipoprotein B-containing lipoprotein particles produced by the RPE. Furthermore, we suggest that the formation of ARMD lesions and their aftermath may be a pathological response to the retention of a sub-endothelial apolipoprotein B lipoprotein, similar to a widely accepted model of atherosclerotic coronary artery disease (Tabas, I., K. J. Williams, and J. Borén. 2007. Subendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implications. Circulation. 116:1832-1844). This view provides a conceptual basis for the development of novel treatments that may benefit ARMD patients in the future.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL, USA.
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73
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Cariou B, Ouguerram K, Zaïr Y, Guerois R, Langhi C, Kourimate S, Benoit I, Le May C, Gayet C, Belabbas K, Dufernez F, Chétiveaux M, Tarugi P, Krempf M, Benlian P, Costet P. PCSK9 dominant negative mutant results in increased LDL catabolic rate and familial hypobetalipoproteinemia. Arterioscler Thromb Vasc Biol 2009; 29:2191-7. [PMID: 19762784 DOI: 10.1161/atvbaha.109.194191] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a central player in the regulation of cholesterol homeostasis, increasing the low-density lipoprotein (LDL) receptor degradation. Our study aimed at exploring the pathogenic consequences in vivo and in vitro of a PCSK9 prodomain mutation found in a family with hypobetalipoproteinemia (FHBL). METHODS AND RESULTS A white 49-year-old diabetic man had profound FBHL (LDLC: 16 mg/dL) whereas his daughter and sister displayed a milder phenotype (LDLC 44 mg/dL and 57 mg/dL, respectively), all otherwise healthy with a normal liver function. A monoallelic PCSK9 double-mutant R104C/V114A cosegregated with FBHL, with no mutation found at other FHBL-causing loci. A dose-effect was also found in FBHL relatives for plasma APOB and PCSK9 (very-low to undetectable in proband, approximately 50% decreased in sister and daughter) and LDL catabolic rate (256% and 88% increased in proband and daughter). Transient transfection in hepatocytes showed severely impaired processing and secretion of the double mutant which acted as a dominant negative over secretion of wild-type PCSK9. CONCLUSIONS These results show that heterozygous PCSK9 missense mutations may associate with profound hypobetalipoproteinemia and constitute the first direct evidence in human that decrease of plasma LDLC concentrations associated to PCSK9 LOF mutations are attributable to an increased clearance rate of LDL.
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74
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Harada N, Soejima Y, Taketomi A, Yoshizumi T, Uchiyama H, Ikegami T, Saibara T, Nishizaki T, Maehara Y. Recurrent familial hypobetalipoproteinemia-induced nonalcoholic fatty liver disease after living donor liver transplantation. Liver Transpl 2009; 15:806-9. [PMID: 19562718 DOI: 10.1002/lt.21766] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Familial hypobetalipoproteinemia (FHBL) is one of the causes of nonalcoholic steatohepatitis (NASH) and a codominant disorder. Patients heterozygous for FHBL may be asymptomatic, although they demonstrate low plasma levels of low-density lipoprotein (LDL) cholesterol and apolipoprotein B. Here we report a nonobese 54-year-old man with decompensated liver cirrhosis who underwent living donor liver transplantation with his son as the donor. Low albuminemia and refractory ascites persisted after transplantation. A biopsy specimen obtained 11 months after liver transplantation revealed severe steatosis and fibrosis, and recurrent NASH was diagnosed on the basis of pathological findings. Both the patient's and donor's laboratory tests demonstrated low LDL cholesterol and apolipoprotein levels. Because mutations in messenger RNAs of microsomal triglyceride transfer protein and apolipoprotein B genes were excluded neither in the recipient nor in the donor, both were clinically diagnosed as being heterozygous for FHBL. We successfully treated the recipient with heterozygous FHBL-induced recurrent NASH after liver transplantation using our diet and exercise programs.
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Affiliation(s)
- Noboru Harada
- Department of Surgery and Medical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
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75
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[Familial hypobetalipoproteinemia: clinical characterization of a new mutation in the APOB gene]. Med Clin (Barc) 2009; 133:57-60. [PMID: 19442995 DOI: 10.1016/j.medcli.2008.10.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Accepted: 10/22/2008] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND OBJECTIVE Familial hypobetalipoproteinemia (FHB) is usually due to mutations in the APOB gene. Almost 60 different mutations have been reported. We report a Spanish family with FHB phenotype and a new mutation. PATIENT AND METHODS We performed an analytical, localizing and molecular study of the APOB gene in the proband and in two relatives phenotypically affected. RESULTS The proband was a 32-year-old woman with moderate to severe mental retardation, morbid obesity, hypocholesterolemia, hypertransaminasemia, and hepatic steatosis. The familial phenotypic study was positive in other 6 relatives. The genetic study confirmed the presence of a novel mutation (apoB-69.27) in the APOB gene. The proband, her mother and one maternal great aunt were heterozygote for that mutation. CONCLUSIONS FHB has a variable phenotypic expression that can range from oligosymptomatic disease to severe neurological damage.
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76
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Pocovi M, Civeira F. Heterogeneidad clínica y genética de la hipobetalipoproteinemia. Med Clin (Barc) 2009; 133:61-2. [DOI: 10.1016/j.medcli.2009.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 03/05/2009] [Indexed: 10/20/2022]
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77
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Cryptogenic cirrhosis in a patient with familial hypocholesterolemia due to a new truncated form of apolipoprotein B. Eur J Gastroenterol Hepatol 2009; 21:104-8. [PMID: 19060634 DOI: 10.1097/meg.0b013e3282ffd9f8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Familial hypobetalipoproteinemia (FHBL) is an autosomal codominantly inherited disorder of lipoprotein metabolism characterized by decreased concentrations of low-density lipoprotein-cholesterol and of apolipoprotein B (apoB). Mutations of APOB gene lead to the formation of truncated forms of apoB. The study aimed at determining the truncated form of apoB responsible for FHBL associated with liver cirrhosis in a 27-year-old man. Analysis of the patient's lipoproteins has been performed by SDS-PAGE electrophoresis followed by immunoblotting with monoclonal antibodies. DNA of the family (proband, daughter, wife, father, and mother) was extracted, and PCR amplification was realized; amplicons were screened and sequenced. Electrophoresis allowed us to identify a truncated form of apoB (close to apoB 59%), associated with a new heterozygous apoB variant, 8402 C>G. This mutation creates a stop codon (TAC>TAG, Y2807X) and predicts to generate a truncated protein (apoB-61.9%). No other causes of cirrhosis were established by comprehensive clinical and biological investigations. We described here an unusual clinical observation of a patient with FHBL and early development of liver cirrhosis due to a new truncated form of apoB.
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78
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Katsuda S, Kawashiri MA, Inazu A, Tada H, Tsuchida M, Kaneko Y, Nozue T, Nohara A, Okada T, Kobayashi J, Michishita I, Mabuchi H, Yamagishi M. Apolipoprotein B gene mutations and fatty liver in Japanese hypobetalipoproteinemia. Clin Chim Acta 2009; 399:64-8. [DOI: 10.1016/j.cca.2008.09.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 08/27/2008] [Accepted: 09/12/2008] [Indexed: 11/26/2022]
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79
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Hooper AJ, van Bockxmeer FM, Burnett JR. Monogenic Hypocholesterolaemic Lipid Disorders and Apolipoprotein B Metabolism. Crit Rev Clin Lab Sci 2008; 42:515-45. [PMID: 16390683 DOI: 10.1080/10408360500295113] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The study of apolipoprotein (apo) B metabolism is central to our understanding of human lipoprotein metabolism. Moreover, the assembly and secretion of apoB-containing lipoproteins is a complex process. Increased plasma concentrations of apoB-containing lipoproteins are an important risk factor for the development of atherosclerotic coronary heart disease. In contrast, decreased levels of, but not the absence of, these apoB-containing lipoproteins is associated with resistance to atherosclerosis and potential long life. The study of inherited monogenic dyslipidaemias has been an effective means to elucidate key metabolic steps and biologically relevant mechanisms. Naturally occurring gene mutations in affected families have been useful in identifying important domains of apoB and microsomal triglyceride transfer protein (MTP) governing the metabolism of apoB-containing lipoproteins. Truncation-causing mutations in the APOB gene cause familial hypobetalipoproteinaemia, whereas mutations in MTP result in abetalipoproteinaemia; both rare conditions are characterised by marked hypocholesterolaemia. The purpose of this review is to examine the role of apoB in lipoprotein metabolism and to explore the key biochemical, clinical, metabolic and genetic features of the monogenic hypocholesterolaemic lipid disorders affecting apoB metabolism.
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Affiliation(s)
- Amanda J Hooper
- School of Surgery and Pathology, University of Western Australia, Crawley, Australia
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80
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Biros E, Karan M, Golledge J. Genetic variation and atherosclerosis. Curr Genomics 2008; 9:29-42. [PMID: 19424482 PMCID: PMC2674308 DOI: 10.2174/138920208783884856] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 02/22/2008] [Accepted: 02/22/2008] [Indexed: 01/06/2023] Open
Abstract
A family history of atherosclerosis is independently associated with an increased incidence of cardiovascular events. The genetic factors underlying the importance of inheritance in atherosclerosis are starting to be understood. Genetic variation, such as mutations or common polymorphisms has been shown to be involved in modulation of a range of risk factors, such as plasma lipoprotein levels, inflammation and vascular calcification. This review presents examples of present studies of the role of genetic polymorphism in atherosclerosis.
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Affiliation(s)
| | | | - Jonathan Golledge
- Vascular Biology Unit, School of Medicine, James Cook University, Townsville, QLD 4811, Australia
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81
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Blasiole DA, Davis RA, Attie AD. The physiological and molecular regulation of lipoprotein assembly and secretion. MOLECULAR BIOSYSTEMS 2007; 3:608-19. [PMID: 17700861 DOI: 10.1039/b700706j] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Triglycerides are insoluble in water and yet are transported at milligram per millilitre concentrations in the bloodstream. This is made possible by the ability of the liver and intestine to assemble lipid-protein emulsions (i.e. lipoproteins), which transport hydrophobic molecules. The assembly of triglyceride-rich lipoproteins requires the coordination of protein and lipid synthesis, which occurs on the cytoplasmic surface of the endoplasmic reticulum (ER), and their concerted assembly and translocation into the luminal ER secretory pathway as nascent lipoprotein particles. The availability of lipid substrate for triglyceride production and the machinery for lipoprotein assembly are highly sensitive to nutritional, hormonal, and genetic modulation. Disorders in lipid metabolism or an imbalance between lipogenesis and lipoprotein assembly can lead to hyperlipidemia and/or hepatic steatosis. We selectively review recently-identified machinery, such as transcription factors and nuclear hormone receptors, which provide new clues to the regulation of lipoprotein secretion.
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Affiliation(s)
- Daniel A Blasiole
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Dr., Madison, WI 53706, USA
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82
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Burnett JR, Zhong S, Jiang ZG, Hooper AJ, Fisher EA, McLeod RS, Zhao Y, Barrett PHR, Hegele RA, van Bockxmeer FM, Zhang H, Vance DE, McKnight CJ, Yao Z. Missense mutations in APOB within the betaalpha1 domain of human APOB-100 result in impaired secretion of ApoB and ApoB-containing lipoproteins in familial hypobetalipoproteinemia. J Biol Chem 2007; 282:24270-83. [PMID: 17588943 DOI: 10.1074/jbc.m702442200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Familial hypobetalipoproteinemia (FHBL) is associated with mutations in the APOB gene. We reported the first missense APOB mutation, R463W, in an FHBL kindred (Burnett, J. R., Shan, J., Miskie, B. A., Whitfield, A. J., Yuan, J., Tran, K., Mc-Knight, C. J., Hegele, R. A., and Yao, Z. (2003) J. Biol. Chem. 278, 13442-13452). Here we identified a second nonsynonymous APOB mutation, L343V, in another FHBL kindred. Heterozygotes for L343V (n = 10) had a mean plasma apoB at 0.31 g/liter as compared with 0.80 g/liter in unaffected family members (n = 22). The L343V mutation impaired secretion of apoB-100 and very low density lipoproteins. The secretion efficiency was 20% for B100wt and 10% for B100LV and B100RW. Decreased secretion of mutant apoB-100 was associated with increased endoplasmic reticulum retention and increased binding to microsomal triglyceride transfer protein and BiP. Reduced secretion efficiency was also observed with B48LV and B17LV. Biochemical and biophysical analyses of apoB domain constructs showed that L343V and R463W altered folding of the alpha-helical domain within the N terminus of apoB. Thus, proper folding of the alpha-helical domain of apoB-100 is essential for efficient secretion.
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Affiliation(s)
- John R Burnett
- Department of Core Clinical Pathology and Biochemistry, Royal Perth Hospital, Australia.
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83
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Tarugi P, Averna M, Di Leo E, Cefalù AB, Noto D, Magnolo L, Cattin L, Bertolini S, Calandra S. Molecular diagnosis of hypobetalipoproteinemia: an ENID review. Atherosclerosis 2007; 195:e19-27. [PMID: 17570373 DOI: 10.1016/j.atherosclerosis.2007.05.003] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 04/27/2007] [Accepted: 05/03/2007] [Indexed: 01/26/2023]
Abstract
Primary hypobetalipoproteinemia (HBL) includes a group of genetic disorders: abetalipoproteinemia (ABL) and chylomicron retention disease (CRD), with a recessive transmission, and familial hypobetalipoproteinemia (FHBL) with a co-dominant transmission. ABL and CRD are rare disorders due to mutations in the MTP and SARA2 genes, respectively. Heterozygous FHBL is much more frequent. FHBL subjects often have fatty liver and, less frequently, intestinal fat malabsorption. FHBL may be linked or not to the APOB gene. Most mutations in APOB gene cause the formation of truncated forms of apoB which may or may be not secreted into the plasma. Truncated apoBs with a size below that of apoB-30 are not detectable in plasma; they are more frequent in patients with the most severe phenotype. Only a single amino acid substitution (R463W) has been reported as the cause of FHBL. Approximately 50% of FHBL subjects are carriers of pathogenic mutations in APOB gene; therefore, a large proportion of FHBL subjects have no apoB gene mutations or are carriers of rare amino acid substitutions in apoB with unknown effect. In some kindred FHBL is linked to a locus on chromosome 3 (3p21) but the candidate gene is unknown. Recently a FHBL plasma lipid phenotype was observed in carriers of mutations of the PCSK9 gene causing loss of function of the encoded protein, a proprotein convertase which regulates LDL-receptor number in the liver. Inactivation of this enzyme is associated with an increased LDL uptake and hypobetalipoproteinemia. HBL carriers of PCSK9 mutations do not develop fatty liver disease.
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Affiliation(s)
- Patrizia Tarugi
- Department of Biomedical Sciences, University of Modena e Reggio Emilia, Via Campi 287, I-41100 Modena, Italy.
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84
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Blanco-Rodríguez M, Muñoz-Calvo MT, Martos-Moreno GA, Abad-Pérez E, Argente-Oliver J. [Familial hypobetalipoproteinemia secondary to a mutation in the apolipoprotein B gene]. An Pediatr (Barc) 2007; 66:535-7. [PMID: 17517208 DOI: 10.1157/13102518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Familial hypobetalipoproteinemia (FHB) is a rare genetically heterogeneous disorder provoking abnormally low serum levels of apoprotein (apo) B, total cholesterol, and low-density lipoprotein (LDL-C). Patients carrying heterozygous mutations in the APOB (2p24) gene are usually asymptomatic, but homozygous mutations cause clinical disturbances as a result of intestinal fat malabsorption and fat-soluble vitamin deficiency. We present an asymptomatic boy, aged 8 years and 7 months, with low serum levels of apo-B, total cholesterol, triglyceride, LDL-C and very low-density lipoprotein (VLDL-C), as well as vitamin E deficiency. Three asymptomatic relatives also exhibited low apo-B, total cholesterol and LDL-C levels. The APOB (2p24) gene was fully sequenced, demonstrating a heterozygous mutation in exon 26 (G --> T) in all four members of this family. Familial genetic studies in FHB could be useful in the early detection and treatment of homozygous carriers.
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Affiliation(s)
- M Blanco-Rodríguez
- Servicio de Endocrinología, Departamento de Pediatría, Hospital Infantil Universitario Niño Jesús, Universidad Autónoma de Madrid, Spain
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85
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Fasano T, Cefalù AB, Di Leo E, Noto D, Pollaccia D, Bocchi L, Valenti V, Bonardi R, Guardamagna O, Averna M, Tarugi P. A Novel Loss of Function Mutation of
PCSK9
Gene in White Subjects With Low-Plasma Low-Density Lipoprotein Cholesterol. Arterioscler Thromb Vasc Biol 2007; 27:677-81. [PMID: 17170371 DOI: 10.1161/01.atv.0000255311.26383.2f] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives—
The
PCSK9
gene, encoding a pro-protein convertase involved in posttranslational degradation of low-density lipoprotein receptor, has emerged as a key regulator of plasma low-density lipoprotein cholesterol. In African-Americans two nonsense mutations resulting in loss of function of PCSK9 are associated with a 30% to 40% reduction of plasma low-density lipoprotein cholesterol. The aim of this study was to assess whether loss of function mutations of PCSK9 were a cause of familial hypobetalipoproteinemia and a determinant of low-plasma low-density lipoprotein cholesterol in whites.
Methods and Results—
We sequenced
PCSK9
gene in 18 familial hypobetalipoproteinemia subjects and in 102 hypocholesterolemic blood donors who were negative for
APOB
gene mutations known to cause familial hypobetalipoproteinemia. The
PCSK9
gene variants found in these 2 groups were screened in 42 subjects in the lowest (<5
th
) percentile, 44 in the highest (>95
th
) percentile, and 100 with the average plasma cholesterol derived from general population. In one familial hypobetalipoproteinemia kindred and in 2 hypocholesterolemic blood donors we found a novel
PCSK9
mutation in exon 1 (c.202delG) resulting in a truncated peptide (Ala68fsLeu82X). Two familial hypobetalipoproteinemia subjects and 4 hypocholesterolemic blood donors were carriers of the R46L substitution previously reported to be associated with reduced low-density lipoprotein cholesterol as well as other rare amino acid changes (T77I, V114A, A522T and P616L) not found in the other groups examined.
Conclusions—
We discovered a novel inactivating mutation as well as some rare nonconservative amino acid substitutions of PCSK9 in white hypocholesterolemic individuals.
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Affiliation(s)
- Tommaso Fasano
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, I-41100 Modena, Italy
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86
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Edgar PF, Hooper AJ, Poa NR, Burnett JR. Violent behavior associated with hypocholesterolemia due to a novel APOB gene mutation. Mol Psychiatry 2007; 12:258-63; 221. [PMID: 17043676 DOI: 10.1038/sj.mp.4001910] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A 26-year-old male, the index patient, presented with persecutory delusions and suicidal behavior. He had 10 paternal male relatives in two prior generations. Five of them died by violent suicide and one, of the five, also committed a double homicide. The index patient was found to be hypocholesterolemic due to being heterozygous for a novel mutation of apolipoprotein B (apoB-29.4). His mother and paternal grandmother were normocholesterolemic, whereas a surviving paternal uncle was hypocholesterolemic and heterozygous for the apoB-29.4 mutation. This indicated that the index patient's father and paternal grandfather, both of which died by violent suicide, were obligate heterozygotes for the apoB-29.4 mutation and that the index patient inherited the mutation from his paternal grandfather. The odds ratio for the association between hypocholesterolemia and violent behavior in this family, where cholesterol status was known, was 16.9 (95% confidence interval 1.1-239.3). Therefore, our results support an inheritable relationship between violent behavior and hypocholesterolemia.
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Affiliation(s)
- P F Edgar
- Molecular Psychiatry Research Group, Department of Psychological Medicine, Christchurch School of Medicine, University of Otago, Christchurch, New Zealand.
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87
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Bock HH, Herz J, May P. Conditional animal models for the study of lipid metabolism and lipid disorders. Handb Exp Pharmacol 2007:407-39. [PMID: 17203665 DOI: 10.1007/978-3-540-35109-2_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The advent of technologies that allow conditional mutagenesis has revolutionized our ability to explore gene functions and to establish animal models of human diseases. Both aspects have proven to be of particular importance in the study of lipid-related disorders. Classical approaches to gene inactivation by conventional gene targeting strategies have been successfully applied to generate animal models like the LDL receptor- and the apolipoprotein E-knockout mice, which are still widely used to study diverse aspects of atherosclerosis, lipid transport, and neurodegenerative disease. In many cases, however, simply inactivating the gene of interest has resulted in early lethal or complex phenotypes which are difficult to interpret. In recent years, additional tools have therefore been developed that allow the spatiotemporally controlled manipulation of the genome, as described in detail in Part I of this volume. Our aim is to provide an exemplary survey of the application of different conditional mutagenesis techniques in lipid research in order to illustrate their potential to unravel physiological functions of a broad range of genes involved in lipid homeostasis.
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Affiliation(s)
- H H Bock
- Zentrum für Neurowissenschaften, Universität Freiburg, Albertstrasse 23, 79104 Freiburg, Germany.
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88
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Putz-Bankuti C, Datz C, März W, Lackner C, Stauber RE, Trauner M, Toplak H, Stojakovic T, Krejs GJ. Clinical-Pathological Conference Series from the Medical University of Graz. Wien Klin Wochenschr 2006; 118:769-75. [PMID: 17186174 DOI: 10.1007/s00508-006-0718-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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89
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Abstract
This review summarizes the mechanisms of cellular cholesterol transport and monogenic human diseases caused by defects in intracellular cholesterol processing. In addition, selected mouse models of disturbed cholesterol trafficking are discussed. Current pharmacological strategies to prevent atherosclerosis are largely based on altering cellular cholesterol balance and are introduced in this context. Finally, because of the organizing potential of cholesterol in membranes, disturbances in cellular cholesterol transport have implications for a wide variety of human diseases, of which selected examples are given.
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Affiliation(s)
- Elina Ikonen
- Institute of Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland.
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90
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Clarke MW, Hooper AJ, Headlam HA, Wu JHY, Croft KD, Burnett JR. Assessment of Tocopherol Metabolism and Oxidative Stress in Familial Hypobetalipoproteinemia. Clin Chem 2006; 52:1339-45. [PMID: 16728468 DOI: 10.1373/clinchem.2006.068692] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AbstractBackground: Vitamin E supplementation has been recommended for persons with familial hypobetalipoproteinemia (FHBL), a rare disorder of lipoprotein metabolism that leads to low serum α-tocopherol and decreased LDL-cholesterol and apolipoprotein (apo) B. We examined the effect of truncated apoB variants on vitamin E metabolism and oxidative stress in persons with FHBL.Methods: We studied 9 individuals with heterozygous FHBL [mean (SE) age, 40 (5) years; body mass index (BMI), 27 (10) kg/m2] and 7 normolipidemic controls [age, 41 (5) years; BMI, 25 (2) kg/m2]. We also studied 3 children—2 with homozygous FHBL (apoB-30.9) and 1 with abetalipoproteinemia—who were receiving α-tocopherol supplementation. We used HPLC with electrochemical detection to measure α- and γ-tocopherol in serum, erythrocytes, and platelets, and gas chromatography–mass spectrometry to measure F2-isoprostanes and tocopherol metabolites in urine as markers of oxidative stress and tocopherol intake, respectively.Results: Compared with controls, persons with FHBL had significantly lower fasting plasma concentrations of total cholesterol [2.4 (0.2) vs 4.7 (0.2) mmol/L], triglycerides [0.5 (0.1) vs 0.9 (0.1) mmol/L], LDL-cholesterol [0.7 (0.1) vs 2.8 (0.3) mmol/L], apoB [0.23 (0.02) vs 0.84 (0.08) g/L], α-tocopherol [13.6 (1.0) vs 28.7 (1.4) μmol/L], and γ-tocopherol [1.0 (0.1) vs 1.8 (0.3) μmol/L] (all P <0.03). Erythrocyte α-tocopherol was decreased [5.0 (0.2) vs 6.0 (0.3) μmol/L; P <0.005], but we observed no differences in lipid-adjusted serum tocopherols, erythrocyte γ-tocopherol, platelet α- or γ-tocopherol, urinary F2-isoprostanes, or tocopherol metabolites.Conclusion: Taken together, our findings do not support the recommendation that persons with heterozygous FHBL receive vitamin E supplementation.
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Affiliation(s)
- Michael W Clarke
- Department of Core Clinical Pathology and Biochemistry, PathWest Laboratory Medicine WA, Royal Perth Hospital, Perth, WA, Australia
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91
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Parhofer KG, Barrett PHR. Thematic review series: patient-oriented research. What we have learned about VLDL and LDL metabolism from human kinetics studies. J Lipid Res 2006; 47:1620-30. [PMID: 16720894 DOI: 10.1194/jlr.r600013-jlr200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipoprotein metabolism is the result of a complex network of many individual components. Abnormal lipoprotein concentrations can result from changes in the production, conversion, or catabolism of lipoprotein particles. Studies in hypolipoproteinemia and hyperlipoproteinemia have elucidated the processes that control VLDL secretion as well as VLDL and LDL catabolism. Here, we review the current knowledge regarding apolipoprotein B (apoB) metabolism, focusing on selected clinically relevant conditions. In hypobetalipoproteinemia attributable to truncations in apoB, the rate of secretion is closely linked to the length of apoB. On the other hand, in patients with the metabolic syndrome, it appears that substrate, in the form of free fatty acids, coupled to the state of insulin resistance can induce hypersecretion of VLDL-apoB. Studies in patients with familial hypercholesterolemia, familial defective apoB, and mutant forms of proprotein convertase subtilisin/kexin type 9 show that mutations in the LDL receptor, the ligand for the receptor, or an intracellular chaperone for the receptor are the most important determinants in regulating LDL catabolism. This review also demonstrates the variance of results within similar, or even the same, phenotypic conditions. This underscores the sensitivity of metabolic studies to methodological aspects and thus the importance of the inclusion of adequate controls in studies.
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92
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Goldberg IJ, Ginsberg HN. Ins and outs modulating hepatic triglyceride and development of nonalcoholic fatty liver disease. Gastroenterology 2006; 130:1343-6. [PMID: 16618425 DOI: 10.1053/j.gastro.2006.02.040] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- Ira J Goldberg
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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93
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Lin X, Yue P, Xie Y, Davidson NO, Sakata N, Ostlund RE, Chen Z, Schonfeld G. Reduced intestinal fat absorptive capacity but enhanced susceptibility to diet-induced fatty liver in mice heterozygous for ApoB38.9 truncation. Am J Physiol Gastrointest Liver Physiol 2005; 289:G146-52. [PMID: 15790761 DOI: 10.1152/ajpgi.00309.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fatty liver is prevalent in apolipoprotein B (apoB)-defective familial hypobetalipoproteinemia (FHBL). Similar to humans, mouse models of FHBL produced by gene targeting (apob(+/38.9)) manifest low plasma cholesterol and increased hepatic triglycerides (TG) even on a chow diet due to impaired hepatic VLDL-TG secretive capacity. Because apoB truncations shorter than apoB48 are expressed in the intestine, we examined whether FHBL mice may have limited capacity for intestinal dietary TG absorption. In addition, we investigated whether FHBL mice are more susceptible to diet-induced hepatic TG accumulation. Fat absorption capacity was impaired in apoB38.9 mice in a gene dose-dependent manner. Relative fractional fat absorption coefficients for apob(+/+), apob(+/38.9), and apob(38.9/38.9) were 1.00, 0.96, and 0.71, respectively. To raise hepatic TG, we fed high-fat (HF) and low-fat (LF) pellets. Hepatic TG level was observed in rank order: HF > LF > chow. On both LF and HF, liver TG level was higher in the apob(+/38.9) than in apob(+/+). Hepatic TG secretion remained impaired in the apob(+/38.9) on the HF diet. Thus the FHBL mice are more susceptible to diet-induced fatty liver despite relatively reduced intestinal TG absorption capacity on a HF diet.
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Affiliation(s)
- Xiaobo Lin
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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94
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Lancellotti S, Zaffanello M, Di Leo E, Costa L, Lonardo A, Tarugi P. Pediatric gallstone disease in familial hypobetalipoproteinemia. J Hepatol 2005; 43:188-91. [PMID: 15894400 DOI: 10.1016/j.jhep.2005.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 03/01/2005] [Accepted: 03/07/2005] [Indexed: 12/04/2022]
Abstract
Familial hypobetalipoproteinemia (FHBL) is an monogenic co-dominant disorder characterized by reduced plasma levels of cholesterol, low density lipoproteins (LDL) and apolipoprotein B (apoB) often associated with non-alcoholic fatty liver disease (NAFLD). It has been suggested that FHBL might predispose to gallstone disease (GD). We report a hypocholesterolemic 10 year old girl with obstructive jaundice due to cholesterol stones in gallbladder and common bile duct which required cholecistectomy. The analysis of patient's plasma lipoproteins revealed a marked reduction of LDL and apoB, a lipid profile consistent with the clinical diagnosis of heterozygous FHBL. The same profile was found in her mother who had severe NAFLD. The analysis of apoB gene, the main candidate gene in FHBL, revealed that the patient and her mother were heterozygotes for a novel nonsense mutation (Y1220X) predicted to cause the formation of a short truncated apoB (apoB-26.87) not secreted into the plasma. The presence of cholesterol stones could result from increased biliary cholesterol secretion as a compensatory mechanism for the reduced capacity of the liver to export cholesterol incorporated into apoB-containing lipoproteins. FHBL should be considered as a possible predisposing factor for cholesterol gallstones in children (190).
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Affiliation(s)
- Sandra Lancellotti
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100 Modena, Italy
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95
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Lin X, Yue P, Chen Z, Schonfeld G. Hepatic triglyceride contents are genetically determined in mice: results of a strain survey. Am J Physiol Gastrointest Liver Physiol 2005; 288:G1179-89. [PMID: 15591160 DOI: 10.1152/ajpgi.00411.2004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To assess whether genetic factor(s) determine liver triglyceride (TG) levels, a 10-mouse strain survey of liver TG contents was performed. Hepatic TG contents were highest in BALB/cByJ, medium in C57BL/6J, and lowest in SWR/J in both genders. Ninety and seventy-six percent of variance in hepatic TG in males and females, respectively, was due to strain (genetic) effects. To understand the physiological/biochemical basis for differences in hepatic TG among the three strains, studies were performed in males of the BALB/cByJ, C57BL/6J, and SWR/J strains. In vivo hepatic fatty acid (FA) synthesis rates and hepatic TG secretion rates ranked BALB/cByJ approximately C57BL/6J > SWR/J. Hepatic 1-(14)C-labeled palmitate oxidation rates and plasma beta-hydroxybutyrate concentrations ranked in reverse order: SWR/J > BALB/cByJ approximately C57BL/6J. After 14 h of fasting, plasma-free FA and hepatic TG contents rose most in BALB/cByJ and least in SWR/J. beta-Hydroxybutyrate concentrations rose least in BALB/cByJ and most in SWR/J. Adaptation to fasting was most effective in SWR/J and least in BALB/cByJ, perhaps because BALB/cByJ are known to be deficient in SCAD, a short-chain FA oxidizing enzyme. To assess the role of insulin action, glucose tolerance test (GTT) was performed. GTT-glucose levels ranked C57BL/6J > BALB/cByJ approximately SWR/J. Thus strain-dependent (genetic) factors play a major role in setting hepatic TG levels in mice. Processes such as FA production and hepatic export in VLDL on the one hand and FA oxidation on the other, explain some of the strain-related differences in hepatic TG contents. Additional factor(s) in the development of fatty liver in BALB/cByJ remain to be demonstrated.
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Affiliation(s)
- Xiaobo Lin
- 660 S. Euclid, Campus Box 8046, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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96
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Di Leo E, Lancellotti S, Penacchioni JY, Cefalù AB, Averna M, Pisciotta L, Bertolini S, Calandra S, Gabelli C, Tarugi P. Mutations in MTP gene in abeta- and hypobeta-lipoproteinemia. Atherosclerosis 2005; 180:311-8. [PMID: 15910857 DOI: 10.1016/j.atherosclerosis.2004.12.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 12/07/2004] [Accepted: 12/15/2004] [Indexed: 10/25/2022]
Abstract
Familial hypobetalipoproteinemia (FHBL) and abetalipoproteinemia (ABL) are inherited disorders of apolipoprotein B (apo B)-containing lipoproteins that result from mutations in apo B and microsomal triglyceride transfer protein (MTP) genes, respectively. Here we report three patients with severe deficiency of plasma low-density lipoprotein (LDL) and apo B. Two of them (probands F.A. and P.E.) had clinical and biochemical phenotype consistent with ABL. Proband F.A. was homozygous for a minute deletion/insertion (c.1228delCCCinsT) in exon 9 of MTP gene predicted to cause a truncated MTP protein of 412 amino acids. Proband P. E. was heterozygous for a mutation in intron 9 (IVS9-1G>A), previously reported in an ABL patient. We failed to find the second pathogenic mutation in MTP gene of this patient. No mutations were found in apo B gene. The third proband (D.F.) had a less severe lipoprotein phenotype which was similar to that of heterozygous FHBL and appeared to be inherited as a co-dominant trait. However, he had no mutations in apo B gene. He was found to be a compound heterozygote for two missense mutations (D384A and G661A), involving highly conserved regions of MTP. Since this proband was also homozygous for varepsilon2 allele of apolipoprotein E (apo E), it is likely that his hypobetalipoproteinemia derives from a combined effect of a mild MTP deficiency and homozygosity for apo E2 isoform.
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Affiliation(s)
- Enza Di Leo
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, I-41100 Modena, Italy
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97
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Yue P, Tanoli T, Wilhelm O, Patterson B, Yablonskiy D, Schonfeld G. Absence of fatty liver in familial hypobetalipoproteinemia linked to chromosome 3p21. Metabolism 2005; 54:682-8. [PMID: 15877300 DOI: 10.1016/j.metabol.2004.12.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Our aim was to ascertain whether fatty liver may be present in the genetic form of familial hypobetalipoproteinemia (FHBL) linked to a susceptibility locus on chromosome 3p21. Three genetic forms of FHBL exist: (a) FHBL caused by truncation-specifying mutations of apolipoprotein B (apoB), (b) FHBL linked to chr3p21, and (c) FHBL not linked either to APOB or to chr3p21. Fatty liver is common in apoB-defective FHBL. Hepatic fat contents were quantified by magnetic resonance spectroscopy in 16 subjects with 3p21-linked FHBL, 32 subjects with apoB-defective FHBL, and 39 sex- and age-matched controls. Mean liver fat of 3p21 subjects was similar to controls and approximately 60% lower than apoB-defective FHBL subjects ( P = .0012). Indices of adiposity (body mass index, waist/hip ratio) and masses of abdominal subcutaneous, retroperitoneal, and intraperitoneal adipose tissue (IPAT) were quantified by MR imaging. Mean measures of adiposity were similar in the 3 groups, suggesting that adiposity per se was not responsible for differences in liver fat. Liver fat content was positively correlated with IPAT. The intercepts of regression lines of IPAT on liver fat content were similar in controls and 3p21, but higher in apoB-defective FHBL subjects. The slopes of the lines were steepest in apoB-defective, intermediate in 3p21, and flattest in controls. Lipoprotein profiles and very low density lipoprotein-apoB100 kinetics of 3p21 and apoB-defective groups also differed. Thus, 2 genetic subtypes of FHBL also differ in several phenotypic features.
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Affiliation(s)
- Pin Yue
- Departments of Internal Medicine and Radiology, Washington University School of Medicine, St. Louis, MO, USA
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98
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Yue P, Isley WL, Harris WS, Rosipal S, Akin CD, Schonfeld G. Genetic variants of ApoE account for variability of plasma low-density lipoprotein and apolipoprotein B levels in FHBL. Atherosclerosis 2005; 178:107-13. [PMID: 15585207 DOI: 10.1016/j.atherosclerosis.2004.06.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Revised: 06/16/2004] [Accepted: 06/28/2004] [Indexed: 10/26/2022]
Abstract
We report two novel APOB mutations causing short apolipoprotein B (apoB) truncations undetectable in plasma and familial hypobetalipoproteinemia (FHBL). In Family 56, a 5 bp deletion in APOB exon 7 (870_874del5) causes a frame shift, converting tyrosine to a stop codon (Y220X) and producing an apoB-5 truncation. In Family 59, a point mutation (1941G>T) in APOB exon 13 converts glutamic acid to stop codon (E578X), specifying apoB-13. A recurrent mutation in exon 26 (4432delT) produces apoB-30.9 in Family 58. In some members of these families, we observed that plasma low-density lipoprotein (LDL) cholesterol and apoB levels were unusually low even for subjects heterozygous for FHBL. To ascertain whether genetic variations in apolipoprotein E (apoE) would explain some of the variations of apoB and LDL cholesterol levels, apoE genotypes were assessed in affected subjects from a total of eight FHBL families with short apoB truncations. Heterozygous FHBL with the epsilon3/epsilon4 genotype had 10-1 5mg/dL higher plasma LDL cholesterol and apoB levels compared to subjects with the epsilon2/epsilon3 and epsilon3/epsilon3 genotypes. The apoE genotype has been reported to account for approximately 10% of the variation of LDL cholesterol in the general population. It accounted for 15-60% of the variability of plasma LDL cholesterol or apoB levels in our FHBL subjects. The physiologic bases for the greater effects of apoE in FHBL remain to be determined.
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Affiliation(s)
- Pin Yue
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University, School of Medicine, St. Louis, MO 63110, USA
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99
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Abstract
Increased serum concentrations of low density lipoproteins represent a major cardiovascular risk factor. Low-density lipoproteins are derived from very low density lipoproteins secreted by the liver. Apolipoprotein (apo)B that constitutes the essential structural protein of these lipoproteins exists in two forms, the full length form apoB-100 and the carboxy-terminal truncated apoB-48. The generation of apoB-48 is due to editing of the apoB mRNA which generates a premature stop translation codon. The editing of apoB mRNA is an important regulatory event because apoB-48-containing lipoproteins cannot be converted into the atherogenic low density lipoproteins. The apoB gene is constitutively expressed in liver and intestine, and the rate of apoB secretion is regulated post-transcriptionally. The translocation of apoB into the endoplasmic reticulum is complicated by the hydrophobicity of the nascent polypeptide. The assembly and secretion of apoB-containing lipoproteins within the endoplasmic reticulum is strictly dependent on the microsomal tricylceride transfer protein which shuttles triglycerides onto the nascent lipoprotein particle. The overall synthesis of apoB lipoproteins is regulated by proteosomal and nonproteosomal degradation and is dependent on triglyceride availability. Noninsulin dependent diabetes mellitus, obesity and the metabolic syndrome are characterized by an increased hepatic synthesis of apoB-containing lipoproteins. Interventions aimed to reduce the hepatic secretion of apoB-containing lipoproteins are therefore of great clinical importance. Lead targets in these pathways are discussed.
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Affiliation(s)
- J Greeve
- Klinik für Allgemeine Innere Medizin, Inselspital-Universitätsspital Bern, Switzerland.
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100
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Marcil V, Peretti N, Delvin E, Levy E. Les processus digestifs et absorptifs des lipides alimentaires. ACTA ACUST UNITED AC 2004; 28:1257-66. [PMID: 15671937 DOI: 10.1016/s0399-8320(04)95219-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Valérie Marcil
- Centre de Recherche Hôpital Sainte-Justine, Département de Nutrition, Université de Montréal, Canada
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