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Auclair N, Sané AT, Ahmarani L, Ould-Chikh NEH, Patey N, Beaulieu JF, Delvin E, Spahis S, Levy E. High-fat diet reveals the impact of Sar1b defects on lipid and lipoprotein profile and cholesterol metabolism. J Lipid Res 2023; 64:100423. [PMID: 37558128 PMCID: PMC10518719 DOI: 10.1016/j.jlr.2023.100423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/26/2023] [Accepted: 07/28/2023] [Indexed: 08/11/2023] Open
Abstract
Biallelic pathogenic variants of the Sar1b gene cause chylomicron retention disease (CRD) whose central phenotype is the inability to secrete chylomicrons. Patients with CRD experience numerous clinical symptoms such as gastrointestinal, hepatic, neuromuscular, ophthalmic, and cardiological abnormalities. Recently, the production of mice expressing either a targeted deletion or mutation of Sar1b recapitulated biochemical and gastrointestinal defects associated with CRD. The present study was conducted to better understand little-known aspects of Sar1b mutations, including mouse embryonic development, lipid profile, and lipoprotein composition in response to high-fat diet, gut and liver cholesterol metabolism, sex-specific effects, and genotype-phenotype differences. Sar1b deletion and mutation produce a lethal phenotype in homozygous mice, which display intestinal lipid accumulation without any gross morphological abnormalities. On high-fat diet, mutant mice exhibit more marked abnormalities in body composition, adipose tissue and liver weight, plasma cholesterol, non-HDL cholesterol and polyunsaturated fatty acids than those on the regular Chow diet. Divergences were also noted in lipoprotein lipid composition, lipid ratios (serving as indices of particle size) and lipoprotein-apolipoprotein distribution. Sar1b defects significantly reduce gut cholesterol accumulation while altering key players in cholesterol metabolism. Noteworthy, variations were observed between males and females, and between Sar1b deletion and mutation phenotypes. Overall, mutant animal findings reveal the importance of Sar1b in several biochemical, metabolic and developmental processes.
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Affiliation(s)
- Nickolas Auclair
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Pharmacology & Physiology, Université de Montréal, Montreal, Quebec, Canada
| | - Alain T Sané
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Léna Ahmarani
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | | | - Nathalie Patey
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Jean-François Beaulieu
- Laboratory of Intestinal Physiopathology, Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Edgard Delvin
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Schohraya Spahis
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Emile Levy
- Research Center, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Pharmacology & Physiology, Université de Montréal, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada.
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2
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Tang VT, Ginsburg D. Cargo selection in endoplasmic reticulum-to-Golgi transport and relevant diseases. J Clin Invest 2023; 133:163838. [PMID: 36594468 PMCID: PMC9797344 DOI: 10.1172/jci163838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Most proteins destined for the extracellular space or various intracellular compartments must traverse the intracellular secretory pathway. The first step is the recruitment and transport of cargoes from the endoplasmic reticulum (ER) lumen to the Golgi apparatus by coat protein complex II (COPII), consisting of five core proteins. Additional ER transmembrane proteins that aid cargo recruitment are referred to as cargo receptors. Gene duplication events have resulted in multiple COPII paralogs present in the mammalian genome. Here, we review the functions of each COPII protein, human disorders associated with each paralog, and evidence for functional conservation between paralogs. We also provide a summary of current knowledge regarding two prototypical cargo receptors in mammals, LMAN1 and SURF4, and their roles in human health and disease.
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Affiliation(s)
- Vi T. Tang
- Department of Molecular and Integrative Physiology,,Life Sciences Institute
| | - David Ginsburg
- Life Sciences Institute,,Department of Internal Medicine,,Department of Human Genetics,,Department of Pediatrics and Communicable Diseases, and,Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, USA
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3
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Peretti N, Mas E. Congenital disorders of intestinal digestion and absorption (sugars, proteins, lipids, ions). Best Pract Res Clin Gastroenterol 2022; 56-57:101785. [PMID: 35331397 DOI: 10.1016/j.bpg.2022.101785] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/29/2021] [Accepted: 01/23/2022] [Indexed: 01/31/2023]
Abstract
Congenital diarrhea may result from 2 main different mechanisms: 1) osmotic diarrhea is caused by the non-digestion-absorption of nutrients leading to the non-absorbed nutrients going into the lumen, increasing the osmotic force and driving fluids; 2) secretory diarrhea induced by the inhibition of intestinal absorption of electrolytes, increasing electrolyte and water flux towards the intestinal lumen. The malabsorption of macronutrients (carbohydrates, proteins and lipids) induces energy deficiency with symptoms depending on the macronutrient: carbohydrates with watery acidic diarrhea; protein with rapid malnutrition, edema, and hypoalbuminemia; and lipids with malnutrition, steatorrhea and hypocholesterolemia. Ionic malabsorption (Cl and Na) is responsible for severe and rapid dehydration sometimes with prenatal abnormalities (polyhydramnios and bowel dilatation).
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Affiliation(s)
- Noel Peretti
- Department of Pediatric Nutrition, Gastroenterology and Hepatology, Hôpital Femme Mère Enfant de Lyon, 59 bd Pinel, 69677, Bron, France; Hospices Civils de Lyon, France.
| | - Emmanuel Mas
- Department of Pediatric Nutrition, Gastroenterology and Hepatology, Hôpital des enfants de Toulouse, 330, avenue de Grande Bretagne, TSA 70034, 31059 Toulouse cedex 9, France; CHU de Toulouse, France
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4
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Karagiannis AD, Mehta A, Dhindsa DS, Virani SS, Orringer CE, Blumenthal RS, Stone NJ, Sperling LS. How low is safe? The frontier of very low (<30 mg/dL) LDL cholesterol. Eur Heart J 2021; 42:2154-2169. [PMID: 33463677 DOI: 10.1093/eurheartj/ehaa1080] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 11/16/2020] [Accepted: 12/18/2020] [Indexed: 02/06/2023] Open
Abstract
Low-density lipoprotein cholesterol (LDL-C) is a proven causative factor for developing atherosclerotic cardiovascular disease. Individuals with genetic conditions associated with lifelong very low LDL-C levels can be healthy. We now possess the pharmacological armamentarium (statins, ezetimibe, PCSK9 inhibitors) to reduce LDL-C to an unprecedented extent. Increasing numbers of patients are expected to achieve very low (<30 mg/dL) LDL-C. Cardiovascular event reduction increases log linearly in association with lowering LDL-C, without reaching any clear plateau even when very low LDL-C levels are achieved. It is still controversial whether lower LDL-C levels are associated with significant clinical adverse effects (e.g. new-onset diabetes mellitus or possibly haemorrhagic stroke) and long-term data are needed to address safety concerns. This review presents the familial conditions characterized by very low LDL-C, analyses trials with lipid-lowering agents where patients attained very low LDL-C, and summarizes the benefits and potential adverse effects associated with achieving very low LDL-C. Given the potential for cardiovascular benefit and short-term safe profile of very low LDL-C, it may be advantageous to attain such low levels in specific high-risk populations. Further studies are needed to compare the net clinical benefit of non-LDL-C-lowering interventions with very low LDL-C approaches, in addition to comparing the efficacy and safety of very low LDL-C levels vs. current recommended targets.
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Affiliation(s)
- Angelos D Karagiannis
- Department of Internal Medicine, Emory University School of Medicine, 1364 Clifton Road NE, Atlanta, GA 30322, USA
| | - Anurag Mehta
- Emory Clinical Cardiovascular Research Institute, Division of Cardiology, Department of Medicine, Emory University School of Medicine, 1462 Clifton Way NE, Atlanta, GA 30322, USA
| | - Devinder S Dhindsa
- Emory Clinical Cardiovascular Research Institute, Division of Cardiology, Department of Medicine, Emory University School of Medicine, 1462 Clifton Way NE, Atlanta, GA 30322, USA
| | - Salim S Virani
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA.,Section of Cardiology, Michael E. DeBakey Veterans Affairs Medical Center, 2002 Holcombe Blvd, Houston, TX 77030, USA
| | - Carl E Orringer
- University of Miami Miller School of Medicine, 1600 NW 10th Ave #1140, Miami, FL 33136, USA
| | - Roger S Blumenthal
- Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease, 601 North Caroline Street Suite 7200, Baltimore, MD 21287, USA
| | - Neil J Stone
- Feinberg School of Medicine, Northwestern University, 420 E Superior St, Chicago, IL 60611, USA
| | - Laurence S Sperling
- Emory Clinical Cardiovascular Research Institute, Division of Cardiology, Department of Medicine, Emory University School of Medicine, 1462 Clifton Way NE, Atlanta, GA 30322, USA
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Auclair N, Sané AT, Ahmarani L, Patey N, Beaulieu JF, Peretti N, Spahis S, Levy E. Sar1b mutant mice recapitulate gastrointestinal abnormalities associated with chylomicron retention disease. J Lipid Res 2021; 62:100085. [PMID: 33964306 PMCID: PMC8175419 DOI: 10.1016/j.jlr.2021.100085] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/15/2021] [Accepted: 04/17/2021] [Indexed: 11/17/2022] Open
Abstract
Chylomicron retention disease (CRD) is an autosomal recessive disorder associated with biallelic Sar1b mutations leading to defects in intracellular chylomicron (CM) trafficking and secretion. To date, a direct cause-effect relationship between CRD and Sar1b mutation has not been established, but genetically modified animal models provide an opportunity to elucidate unrecognized aspects of these mutations. To examine the physiological role and molecular mechanisms of Sar1b function, we generated mice expressing either a targeted deletion or mutation of human Sar1b using the CRISPR-Cas9 system. We found that deletion or mutation of Sar1b in mice resulted in late-gestation lethality of homozygous embryos. Moreover, compared with WT mice, heterozygotes carrying a single disrupted Sar1b allele displayed lower plasma levels of triglycerides, total cholesterol, and HDL-cholesterol, along with reduced CM secretion following gastric lipid gavage. Similarly, decreased expression of apolipoprotein B and microsomal triglyceride transfer protein was observed in correlation with the accumulation of mucosal lipids. Inefficient fat absorption in heterozygotes was confirmed via an increase in fecal lipid excretion. Furthermore, genetically modified Sar1b affected intestinal lipid homeostasis as demonstrated by enhanced fatty acid β-oxidation and diminished lipogenesis through the modulation of transcription factors. This is the first reported mammalian animal model with human Sar1b genetic defects, which reproduces some of the characteristic CRD features and provides a direct cause-effect demonstration.
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Affiliation(s)
- Nickolas Auclair
- Research Center, CHU Ste-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Pharmacology & Physiology, Université de Montréal, Montreal, Quebec, Canada
| | - Alain T Sané
- Research Center, CHU Ste-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Lena Ahmarani
- Research Center, CHU Ste-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Nathalie Patey
- Research Center, CHU Ste-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Pathology, Université de Montréal, Montreal, Quebec, Canada
| | - Jean-François Beaulieu
- Laboratory of Intestinal Physiopathology, Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Noel Peretti
- Department of Pediatric Gastroenterology-Hepatology and Nutrition, Laboratory INSERM 1060 Cardiovascular Metabolism Endocrinology and Nutrition CarMEN, Lyon, France
| | - Schohraya Spahis
- Research Center, CHU Ste-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Emile Levy
- Research Center, CHU Ste-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Pharmacology & Physiology, Université de Montréal, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada.
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6
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Abstract
Chylomicrons and very-low-density lipoproteins (VLDLs) are large, complex cargos that may require specific chaperones for efficient transport from the ER to Golgi. In this issue of Cell Metabolism, Wang et al. (2020) identify SURF4, in coordination with SAR1B, as an essential player in COPII transport of VLDLs from ER to Golgi, suggesting that SURF4 may be a target for approaches aimed at reducing secretion of triglyceride-rich, atherogenic lipoproteins from the liver.
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Affiliation(s)
- Henry N Ginsberg
- Department of Medicine, Vagelos College of Physicians and Surgeons of Columbia University, New York, NY, USA.
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Levy E, Beaulieu JF, Spahis S. From Congenital Disorders of Fat Malabsorption to Understanding Intra-Enterocyte Mechanisms Behind Chylomicron Assembly and Secretion. Front Physiol 2021; 12:629222. [PMID: 33584351 PMCID: PMC7873531 DOI: 10.3389/fphys.2021.629222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/06/2021] [Indexed: 11/13/2022] Open
Abstract
During the last two decades, a large body of information on the events responsible for intestinal fat digestion and absorption has been accumulated. In particular, many groups have extensively focused on the absorptive phase in order to highlight the critical "players" and the main mechanisms orchestrating the assembly and secretion of chylomicrons (CM) as essential vehicles of alimentary lipids. The major aim of this article is to review understanding derived from basic science and clinical conditions associated with impaired packaging and export of CM. We have particularly insisted on inborn metabolic pathways in humans as well as on genetically modified animal models (recapitulating pathological features). The ultimate goal of this approach is that "experiments of nature" and in vivo model strategy collectively allow gaining novel mechanistic insight and filling the gap between the underlying genetic defect and the apparent clinical phenotype. Thus, uncovering the cause of disease contributes not only to understanding normal physiologic pathway, but also to capturing disorder onset, progression, treatment and prognosis.
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Affiliation(s)
- Emile Levy
- Research Centre, CHU Ste-Justine, Université de Montréal, Montreal, QC, Canada
- Department of Nutrition, Université de Montréal, Montreal, QC, Canada
- Department of Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Jean François Beaulieu
- Laboratory of Intestinal Physiopathology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Schohraya Spahis
- Research Centre, CHU Ste-Justine, Université de Montréal, Montreal, QC, Canada
- Department of Nutrition, Université de Montréal, Montreal, QC, Canada
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8
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Melville DB, Studer S, Schekman R. Small sequence variations between two mammalian paralogs of the small GTPase SAR1 underlie functional differences in coat protein complex II assembly. J Biol Chem 2020; 295:8401-8412. [PMID: 32358066 PMCID: PMC7307210 DOI: 10.1074/jbc.ra120.012964] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/27/2020] [Indexed: 01/03/2023] Open
Abstract
Vesicles that are coated by coat protein complex II (COPII) are the primary mediators of vesicular traffic from the endoplasmic reticulum to the Golgi apparatus. Secretion-associated Ras-related GTPase 1 (SAR1) is a small GTPase that is part of COPII and, upon GTP binding, recruits the other COPII proteins to the endoplasmic reticulum membrane. Mammals have two SAR1 paralogs that genetic data suggest may have distinct physiological roles, e.g. in lipoprotein secretion in the case of SAR1B. Here we identified two amino acid clusters that have conserved SAR1 paralog–specific sequences. We observed that one cluster is adjacent to the SAR1 GTP-binding pocket and alters the kinetics of GTP exchange. The other cluster is adjacent to the binding site for two COPII components, SEC31 homolog A COPII coat complex component (SEC31) and SEC23. We found that the latter cluster confers to SAR1B a binding preference for SEC23A that is stronger than that of SAR1A for SEC23A. Unlike SAR1B, SAR1A was prone to oligomerize on a membrane surface. SAR1B knockdown caused loss of lipoprotein secretion, overexpression of SAR1B but not of SAR1A could restore secretion, and a divergent cluster adjacent to the SEC31/SEC23-binding site was critical for this SAR1B function. These results highlight that small primary sequence differences between the two mammalian SAR1 paralogs lead to pronounced biochemical differences that significantly affect COPII assembly and identify a specific function for SAR1B in lipoprotein secretion, providing insights into the mechanisms of large cargo secretion that may be relevant for COPII-related diseases.
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Affiliation(s)
- David B Melville
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, USA
| | - Sean Studer
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, USA
| | - Randy Schekman
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, USA
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9
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Simone ML, Rabacchi C, Kuloglu Z, Kansu A, Ensari A, Demir AM, Hizal G, Di Leo E, Bertolini S, Calandra S, Tarugi P. Novel mutations of SAR1B gene in four children with chylomicron retention disease. J Clin Lipidol 2019; 13:554-562. [DOI: 10.1016/j.jacl.2019.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/30/2019] [Accepted: 05/23/2019] [Indexed: 10/26/2022]
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10
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Abstract
PURPOSE OF REVIEW Chylomicron retention disease (CRD) is an autosomic recessive disorder, in which intestinal fat malabsorption is the main cause of diverse severe manifestations. The specific molecular defect was identified in 2003 and consists of mutations in the SAR1B or SARA2 gene encoding for intracellular SAR1B GTPase protein. The aim of this review is first to provide an update of the recent biochemical, genetic and clinical findings, and second to discuss novel mechanisms related to hallmark symptoms. RECENT FINDINGS CRD patients present with SAR1B mutations, which disable the formation of coat protein complex II and thus blocks the transport of chylomicron cargo from the endoplasmic reticulum to the Golgi. Consequently, there is a total absence of chylomicron and apolipoprotein B-48 in the blood circulation following a fat meal, accompanied by a deficiency in liposoluble vitamins and essential fatty acids. The recent discovery of Transport and Golgi organization and Transport and Golgi organization-like proteins may explain the intriguing export of large chylomicron, exceeding coat protein complex II size. Hypocholesterolemia could be accounted for by a decrease in HDL cholesterol, likely a reflection of limited production of intestinal HDL in view of reduced ATP-binding cassette family A protein 1 and apolipoprotein A-I protein. In experimental studies, the paralog SAR1A compensates for the lack of the SAR1B GTPase protein. SUMMARY Molecular testing for CRD is recommended to distinguish the disease from other congenital fat malabsorptions, and to early define molecular aberrations, accelerate treatment, and prevent complications.
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Affiliation(s)
- Emile Levy
- Research Centre
- Gastroenterology, Hepatology and Nutrition Unit, CHU Ste-Justine
- Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Pierre Poinsot
- Gastroenterology, Hepatology and Nutrition Unit, CHU Ste-Justine
| | - Schohraya Spahis
- Research Centre
- Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
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11
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Clinical and genetic spectrum of children with congenital diarrhea and enteropathy in China. Genet Med 2019; 21:2224-2230. [PMID: 30894704 DOI: 10.1038/s41436-019-0488-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 03/01/2019] [Indexed: 02/08/2023] Open
Abstract
PURPOSE Genetic sequencing for children with congenital diarrhea and enteropathy (CODE) has important implications for the diagnosis, prognosis, and implementation of precision medicine. METHODS We performed exome sequencing or targeted panel sequencing on 137 children with CODE. Endoscopic, imaging, histological, and immunological assessments were also applied. Patients were divided into three subgroups: watery, fatty, and bloody diarrhea. RESULTS The median age of onset among patients was 28.0 (interquartile range: 7.5-120.0) days. Genetic diagnosis was achieved in 88/137 (64.2%) of patients. The diagnostic rate was significantly higher in the neonatal group than in the group of patients who had disease onset within 2 years of age (p = 0.033). The diagnostic rates were 71.9% (46/64) for targeted gene panel sequencing and 57.5% (42/73) for exome sequencing (p = 0.081). We identified pathogenic variants in 17 genes. Based on genetic sequencing, 59.9% of patients were diagnosed with medically actionable disorders. Precision medicine was carried out by means of hematopoietic stem cell transplantation for patients with IL10RA, CYBB, or FOXP3 deficiency; pancreatic enzyme replacement for patients with SBDS or UBR1 deficiency; and a special diet for patients with SLC5A1 deficiency. The overall mortality rate was 14.6%. CONCLUSION Single-gene disorders are common among CODE patients. Genetic diagnosis can improve therapy by enabling precision medicine.
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12
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Melville D, Gorur A, Schekman R. Fatty-acid binding protein 5 modulates the SAR1 GTPase cycle and enhances budding of large COPII cargoes. Mol Biol Cell 2018; 30:387-399. [PMID: 30485159 PMCID: PMC6589570 DOI: 10.1091/mbc.e18-09-0548] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
COPII-coated vesicles are the primary mediators of ER-to-Golgi trafficking. Sar1, one of the five core COPII components, is a highly conserved small GTPase, which, upon GTP binding, recruits the other COPII proteins to the ER membrane. It has been hypothesized that the changes in the kinetics of SAR1 GTPase may allow for the secretion of large cargoes. Here we developed a cell-free assay to recapitulate COPII-dependent budding of large lipoprotein cargoes from the ER. We identified fatty-acid binding protein 5 (FABP5) as an enhancer of this budding process. We found that FABP5 promotes the budding of particles ∼150 nm in diameter and modulates the kinetics of the SAR1 GTPase cycle. We further found that FABP5 enhances the trafficking of lipoproteins and of other cargoes, including collagen. These data identify a novel regulator of SAR1 GTPase activity and highlight the importance of this activity for trafficking of large cargoes.
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Affiliation(s)
- David Melville
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Amita Gorur
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Randy Schekman
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720
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Ferreira H, Ramos RN, Quan CF, Ferreiro SR, Ruiz VC, Juampérez Goñi J, Quintero Bernabeu J, Segarra Cantón O, Álvarez Beltran M. Chylomicron Retention Disease: a Description of a New Mutation in a Very Rare Disease. Pediatr Gastroenterol Hepatol Nutr 2018; 21:134-140. [PMID: 29713611 PMCID: PMC5915691 DOI: 10.5223/pghn.2018.21.2.134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/24/2017] [Accepted: 10/14/2017] [Indexed: 11/14/2022] Open
Abstract
Chylomicron retention disease, also known as Anderson's disease, is a rare hereditary hypocholesterolemic disorder, recessive inherited, characterized by nonspecific symptoms as abdominal distension, steatorrhea, and vomiting associated with failure to thrive. We describe a patient with failure to thrive, chronic diarrhea and steatorrhea who the diagnosis of chylomicron retention disease was established after several months of disease progression. The genetic study confirmed a homozygosity mutation in SAR1B gene, identifying a mutation never previous described [c.83_84delTG(p.Leu28Argfs*7)]. With this case report the authors aim to highlight for this very rare cause of failure to thrive and for the importance of an attempting diagnosis, in order to start adequate management with low fat diet supplemented with fat-soluble vitamins, reverting the state of malnutrition and avoiding possible irreversible and desvantating complications.
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Affiliation(s)
- Helena Ferreira
- Department of Pediatric, Hospital da Senhora da Oliveira, Guimarães, Portugal
| | - Raquel Nuñez Ramos
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Cinthia Flores Quan
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Susana Redecillas Ferreiro
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Vanessa Cabello Ruiz
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Javi Juampérez Goñi
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Jesus Quintero Bernabeu
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Oscar Segarra Cantón
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
| | - Marina Álvarez Beltran
- Department of Pediatric and Gastroenterology, Hepatology, Nutritional Support and Liver Transplant Unit, Hospital Universitário Vall d'Hebron, Barcelona, Spain
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14
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Peretti N. Lessons from chylomicron retention disease: a potential new approach for the treatment of hypercholesterolemia? Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1438259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Noel Peretti
- Hospices Civils de Lyon, Department of Pediatric Nutrition, Hopital Femme Mere Enfant HFME, Bron, France
- Univ-Lyon, CarMeN laboratory, INSERM U1060, INRA U1397, Université Claude Bernard Lyon 1, INSA Lyon, Charles Merieux Medical School, Oullins, France
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15
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Sané AT, Seidman E, Peretti N, Kleme ML, Delvin E, Deslandres C, Garofalo C, Spahis S, Levy E. Understanding Chylomicron Retention Disease Through Sar1b Gtpase Gene Disruption: Insight From Cell Culture. Arterioscler Thromb Vasc Biol 2017; 37:2243-2251. [PMID: 28982670 DOI: 10.1161/atvbaha.117.310121] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/21/2017] [Indexed: 01/28/2023]
Abstract
BACKGROUND Understanding the specific mechanisms of rare autosomal disorders has greatly expanded insights into the complex processes regulating intestinal fat transport. Sar1B GTPase is one of the critical proteins governing chylomicron secretion by the small intestine, and its mutations lead to chylomicron retention disease, despite the presence of Sar1A paralog. OBJECTIVE The central aim of this work is to examine the cause-effect relationship between Sar1B expression and chylomicron output and to determine whether Sar1B is obligatory for normal high-density lipoprotein biogenesis. APPROACH AND RESULTS The SAR1B gene was totally silenced in Caco-2/15 cells using the zinc finger nuclease technique. SAR1B deletion resulted in significantly decreased secretion of triglycerides (≈40%), apolipoprotein B-48 (≈57%), and chylomicron (≈34.5%). The absence of expected chylomicron production collapse may be because of the compensatory SAR1A elevation observed in our experiments. Therefore, a double knockout of SAR1A and SAR1B was engineered in Caco-2/15 cells, which led to almost complete inhibition of triglycerides, apolipoprotein B-48, and chylomicron output. Further experiments with labeled cholesterol revealed the downregulation of high-density lipoprotein biogenesis in cells deficient in SAR1B or with the double knockout of the 2 SAR1 paralogs. Similarly, there was a fall in the movement of labeled cholesterol from cells to basolateral medium containing apolipoprotein A-I, thereby limiting newly synthesized high-density lipoprotein in genetically modified cells. The decreased cholesterol efflux was associated with impaired expression of ABCA1 (ATP-binding cassette subfamily A member 1). CONCLUSIONS These findings demonstrate that the deletion of the 2 SAR1 isoforms is required to fully eliminate the secretion of chylomicron in vitro. They also underscore the limited high-density lipoprotein production by the intestinal cells in response to SAR1 knockout.
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Affiliation(s)
- Alain Théophile Sané
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Ernest Seidman
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Noel Peretti
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Marie Laure Kleme
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Edgard Delvin
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Colette Deslandres
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Carole Garofalo
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Schohraya Spahis
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.)
| | - Emile Levy
- From the CHU Sainte-Justine Research Centre (A.T.S., M.L.K., E.D., C.D., C.G., S.S., E.L.), Department of Nutrition (M.L.K., S.S., E.L.), and Department of Pediatrics (C.D.), Université de Montréal, Quebec, Canada; Division of Gastroenterology, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada (E.S.); and Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Université de Lyon 1, France (N.P.).
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Sané A, Seidman E, Spahis S, Lamantia V, Garofalo C, Montoudis A, Marcil V, Levy E. New Insights In Intestinal Sar1B GTPase Regulation and Role in Cholesterol Homeostasis. J Cell Biochem 2016; 116:2270-82. [PMID: 25826777 DOI: 10.1002/jcb.25177] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 03/25/2015] [Indexed: 12/12/2022]
Abstract
Sar1B GTPase is a key component of Coat protein complex II (COPII)-coated vesicles that bud from the endoplasmic reticulum to export newly synthesized proteins. The aims of this study were to determine whether Sar1B responds to lipid regulation and to evaluate its role in cholesterol (CHOL) homeostasis. The influence of lipids on Sar1B protein expression was analyzed in Caco-2/15 cells by Western blot. Our results showed that the presence of CHOL (200 μM) and oleic acid (0.5 mM), bound to albumin, increases Sar1B protein expression. Similarly, supplementation of the medium with micelles composed of taurocholate with monooleylglycerol or oleic acid also stimulated Sar1B expression, but the addition of CHOL (200 μM) to micelle content did not modify its regulation. On the other hand, overexpression of Sar1B impacted on CHOL transport and metabolism in view of the reduced cellular CHOL content along with elevated secretion when incubated with oleic acid-containing micelles for 24 h, thereby disclosing induced CHOL transport. This was accompanied with higher secretion of free- and esterified-CHOL within chylomicrons, which was not the case when oleic acid was replaced with monooleylglycerol or when albumin-bound CHOL was given alone. The aforementioned cellular CHOL depletion was accompanied with a low phosphorylated/non phosphorylated HMG-CoA reductase ratio, indicating elevated enzymatic activity. Combination of Sar1B overexpression with micelle incubation led to reduction in intestinal CHOL transporters (NPC1L1, SR-BI) and metabolic regulators (PCSK9 and LDLR). The present work showed that Sar1B is regulated in a time- and concentration-dependent manner by dietary lipids, suggesting an adaptation to alimentary lipid flux. Our data also suggest that Sar1B overexpression contributes to regulation of CHOL transport and metabolism by facilitating rapid uptake and transport of CHOL.
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Affiliation(s)
- Alain Sané
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
| | - Ernest Seidman
- Research Institute, McGill University, Campus MGH, C10.148.6, Montreal, Quebec, Canada, H3G 1A4
| | - Schohraya Spahis
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada, H3T 1A8
| | - Valérie Lamantia
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
| | - Carole Garofalo
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
| | - Alain Montoudis
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
| | - Valérie Marcil
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5.,Research Institute, McGill University, Campus MGH, C10.148.6, Montreal, Quebec, Canada, H3G 1A4
| | - Emile Levy
- Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada, H3T 1A8
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Update on the molecular biology of dyslipidemias. Clin Chim Acta 2016; 454:143-85. [DOI: 10.1016/j.cca.2015.10.033] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/24/2015] [Accepted: 10/30/2015] [Indexed: 12/20/2022]
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Animal model of Sar1b deficiency presents lipid absorption deficits similar to Anderson disease. J Mol Med (Berl) 2015; 93:165-76. [PMID: 25559265 DOI: 10.1007/s00109-014-1247-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 11/19/2014] [Accepted: 12/18/2014] [Indexed: 01/25/2023]
Abstract
Anderson disease (ANDD) or chylomicron retention disease (CMRD) is a rare, hereditary lipid malabsorption syndrome associated with mutations in the SAR1B gene that is characterized by failure to thrive and hypocholesterolemia. Although the SAR1B structure has been resolved and its role in formation of coat protein II (COPII)-coated carriers is well established, little is known about the requirement for SAR1B during embryogenesis. To address this question, we have developed a zebrafish model of Sar1b deficiency based on antisense oligonucleotide knockdown. We show that zebrafish sar1b is highly conserved among vertebrates; broadly expressed during development; and enriched in the digestive tract organs, brain, and craniofacial skeleton. Consistent with ANDD symptoms of chylomicron retention, we found that dietary lipids in Sar1b-deficient embryos accumulate in enterocytes. Transgenic expression analysis revealed that Sar1b is required for growth of exocrine pancreas and liver. Furthermore, we found abnormal differentiation and maturation of craniofacial cartilage associated with defects in procollagen II secretion and absence of select, neuroD-positive neurons of the midbrain and hindbrain. The model presented here will help to systematically dissect developmental roles of Sar1b and to discover molecular and cellular mechanisms leading to organ-specific ANDD pathology. Key messages: Sar1b depletion phenotype in zebrafish resembles Anderson disease deficits. Sar1b deficiency results in multi-organ developmental deficits. Sar1b is required for dietary cholesterol uptake into enterocytes.
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Abstract
"Primary hypobetalipoproteinemia" refers to an eclectic group of inherited lipoprotein disorders characterized by low concentrations of or absence of low-density lipoprotein cholesterol and apolipoprotein B in plasma. Abetalipoproteinemia and homozygous familial hypobetalipoproteinemia, although caused by mutations in different genes, are clinically indistinguishable. A framework for the clinical follow-up and management of these two disorders has been proposed recently, focusing on monitoring of growth in children and preventing complications by providing specialized dietary advice and fat-soluble vitamin therapeutic regimens. Other recent publications on familial combined hypolipidemia suggest that although a reduction of angiopoietin-like 3 activity may improve insulin sensitivity, complete deficiency also reduces serum cholesterol efflux capacity and increases the risk of early vascular atherosclerotic changes, despite low low-density lipoprotein cholesterol levels. Specialist laboratories offer exon-by-exon sequence analysis for the molecular diagnosis of primary hypobetalipoproteinemia. In the future, massively parallel sequencing of panels of genes involved in dyslipidemia may play a greater role in the diagnosis of these conditions.
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Levy E. Insights from human congenital disorders of intestinal lipid metabolism. J Lipid Res 2014; 56:945-62. [PMID: 25387865 DOI: 10.1194/jlr.r052415] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Indexed: 12/24/2022] Open
Abstract
The intestine must challenge the profuse daily flux of dietary fat that serves as a vital source of energy and as an essential component of cell membranes. The fat absorption process takes place in a series of orderly and interrelated steps, including the uptake and translocation of lipolytic products from the brush border membrane to the endoplasmic reticulum, lipid esterification, Apo synthesis, and ultimately the packaging of lipid and Apo components into chylomicrons (CMs). Deciphering inherited disorders of intracellular CM elaboration afforded new insight into the key functions of crucial intracellular proteins, such as Apo B, microsomal TG transfer protein, and Sar1b GTPase, the defects of which lead to hypobetalipoproteinemia, abetalipoproteinemia, and CM retention disease, respectively. These "experiments of nature" are characterized by fat malabsorption, steatorrhea, failure to thrive, low plasma levels of TGs and cholesterol, and deficiency of liposoluble vitamins and essential FAs. After summarizing and discussing the functions and regulation of these proteins for reader's comprehension, the current review focuses on their specific roles in malabsorptions and dyslipidemia-related intestinal fat hyperabsorption while dissecting the spectrum of clinical manifestations and managements. The influence of newly discovered proteins (proprotein convertase subtilisin/kexin type 9 and angiopoietin-like 3 protein) on fat absorption has also been provided. Finally, it is stressed how the overexpression or polymorphism status of the critical intracellular proteins promotes dyslipidemia and cardiometabolic disorders.
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Affiliation(s)
- Emile Levy
- Research Centre, CHU Sainte-Justine and Department of Nutrition, Université de Montréal, Montreal, Quebec H3T 1C5, Canada
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Levy E, Spahis S, Garofalo C, Marcil V, Montoudis A, Sinnet D, Sanchez R, Peretti N, Beaulieu JF, Sane A. Sar1b transgenic male mice are more susceptible to high-fat diet-induced obesity, insulin insensitivity and intestinal chylomicron overproduction. J Nutr Biochem 2014; 25:540-8. [PMID: 24657056 DOI: 10.1016/j.jnutbio.2014.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 12/28/2013] [Accepted: 01/08/2014] [Indexed: 12/13/2022]
Abstract
In the intracellular secretory network, nascent proteins are shuttled from the endoplasmic reticulum to the Golgi by transport vesicles requiring Sar1b, a small GTPase. Mutations in this key enzyme impair intestinal lipid transport and cause chylomicron retention disease. The main aim of this study was to assess whether Sar1b overexpression under a hypercaloric diet accelerated lipid production and chylomicron (CM) secretion, thereby inducing cardiometabolic abnormalities. To this end, we generated transgenic mice overexpressing human Sar1b (Sar1b(+/+)) using pBROAD3-mcs that features the ubiquitous mouse ROSA26 promoter. In response to a high-fat diet (HFD), Sar1b(+/+) mice displayed significantly increased body weight and adiposity compared with Sar1b(+/+) mice under the same regimen or with wild-type (WT) mice exposed to chow diet or HFD. Furthermore, Sar1b(+/+) mice were prone to liver steatosis as revealed by significantly elevated hepatic triglycerides (TG) and cholesterol in comparison with WT animals. They also exhibited augmented levels of plasma TG along with alterations in fatty acid composition. Concomitantly, they showed susceptibility to develop insulin insensitivity and they responded abnormally to oral glucose tolerance test. Finally, Sar1b(+/+) mice that have been treated with Triton WR-1330 (to inhibit TG catabolism) and orotic acid (to block secretion of very low-density lipoprotein by the liver) responded more efficiently to fat meal tests as reflected by the rise in plasma TG and CM concentrations, indicating exaggerated intestinal fat absorption. These results suggest that Sar1b(+/+) under HFD can elicit cardiometabolic traits as revealed by incremental weight gain, fat deposition, dyslipidemia, hepatic steatosis, insulin insensitivity and intestinal fat absorption.
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Affiliation(s)
- Emile Levy
- Research Center, Sainte-Justine UHC, Montreal, Quebec, Canada, H3T 1C5; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada, H3T 1J4; Canadian Institutes for Health Research Team on the Digestive Epithelium, Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada, J1H 5N4.
| | - Schohraya Spahis
- Research Center, Sainte-Justine UHC, Montreal, Quebec, Canada, H3T 1C5; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada, H3T 1J4
| | - Carole Garofalo
- Research Center, Sainte-Justine UHC, Montreal, Quebec, Canada, H3T 1C5
| | - Valérie Marcil
- Research Institute, McGill University, Montreal, Quebec, Canada, H3G 1A4
| | - Alain Montoudis
- Research Center, Sainte-Justine UHC, Montreal, Quebec, Canada, H3T 1C5
| | - Daniel Sinnet
- Department of Pediatrics, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
| | - Rocio Sanchez
- Research Center, Sainte-Justine UHC, Montreal, Quebec, Canada, H3T 1C5
| | - Noel Peretti
- Centre de recherche Rhône-Alpes en nutrition humaine, Hôpital Edouard-Herriot, Faculté de Médicine, Université de Lyon-1, France
| | - Jean-François Beaulieu
- Canadian Institutes for Health Research Team on the Digestive Epithelium, Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada, J1H 5N4
| | - Alain Sane
- Research Center, Sainte-Justine UHC, Montreal, Quebec, Canada, H3T 1C5
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Xiao C, Lewis GF. Regulation of chylomicron production in humans. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:736-46. [DOI: 10.1016/j.bbalip.2011.09.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 09/20/2011] [Accepted: 09/21/2011] [Indexed: 12/18/2022]
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Ouguerram K, Zaïr Y, Kasbi-Chadli F, Nazih H, Bligny D, Schmitz J, Aparicio T, Chétiveaux M, Magot T, Aggerbeck LP, Samson-Bouma ME, Krempf M. Low rate of production of apolipoproteins B100 and AI in 2 patients with Anderson disease (chylomicron retention disease). Arterioscler Thromb Vasc Biol 2012; 32:1520-5. [PMID: 22441101 DOI: 10.1161/atvbaha.112.245076] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Anderson disease is a rare inherited lipid malabsorption syndrome associated with hypocholesterolemia and linked to SAR1B mutations. The aim of this article was to analyze the mechanisms responsible for the low plasma apolipoprotein Apo-B100 and Apo-AI in 2 patients with Anderson disease. METHODS AND RESULTS A primed constant infusion of (13)C-leucine was administered for 14 hours to determine the kinetics of lipoproteins. In the 2 patients, total cholesterol (77 and 85 mg/dL versus 155±32 mg/dL), triglycerides (36 and 59 versus 82±24 mg/dL), Apo-B100 (48 and 43 versus 71±5 mg/dL), and Apo-AI (47 and 62 versus 130±7 mg/dL) were lower compared with 6 healthy individuals. Very-low-density lipoprotein-B100 production rate of the patients was lower (4.08 and 5.52 mg/kg/day versus 12.96±2.88 mg/kg/day) as was the fractional catabolic rate (5.04 and 4.32 day(-1) versus 12.24±3.84 day(-1)). No difference was observed in intermediate-density lipoprotein-B100 and LDL-B100 kinetic data. The production rate of high-density lipoprotein Apo-AI was lower in the patients (7.92 and 8.64 versus 11.96±1.92 mg/kg/day) and the fractional catabolic rate was higher (0.38 and 0.29 versus 0.22±0.01 day(-1)). CONCLUSIONS The low plasma Apo-B100 and Apo-AI concentrations in the patients with Anderson disease were mainly related to low rates of production.
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Affiliation(s)
- Khadija Ouguerram
- INSERM UMR 1087/CNRS UMR 6291 and CRNH Nantes, IRT-UN, Nantes, France
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Levy E, Harmel E, Laville M, Sanchez R, Emonnot L, Sinnett D, Ziv E, Delvin E, Couture P, Marcil V, Sane AT. Expression of Sar1b enhances chylomicron assembly and key components of the coat protein complex II system driving vesicle budding. Arterioscler Thromb Vasc Biol 2012; 31:2692-9. [PMID: 21836065 DOI: 10.1161/atvbaha.111.233908] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE SAR1b plays a significant role in the assembly, organization, and function of the coat protein complex II, a critical complex for the transport of proteins from the endoplasmic reticulum to the Golgi. Recently, mutations in SARA2 have been associated with lipid absorption disorders. However, functional studies on Sar1b-mediated lipid synthesis pathways and lipoprotein packaging have not been performed. METHODS AND RESULTS Sar1b was overexpressed in Caco-2/15 cells and resulted in significantly augmented triacylglycerol, cholesteryl ester, and phospholipid esterification and secretion and markedly enhanced chylomicron production. It also stimulated monoacylglycerol acyltransferase/diacylglycerol acyltransferase activity and enhanced apolipoprotein B-48 protein synthesis, as well as elevated microsomal triglyceride transfer protein activity. Along with the enhanced chylomicrons, microsomes were characterized by abundant Sec12, the guanine exchange factor that promotes the localization of Sar1b in the endoplasmic reticulum. Furthermore, coimmunoprecipitation experiments revealed high levels of the complex components Sec23/Sec24 and p125, the Sec23-interacting protein. Finally, a pronounced interaction of Sec23/Sec24 with sterol regulatory element binding protein (SREBP) cleavage-activating protein and SREBP-1c was noted, thereby permitting the transfer of the transcription factor SREBP-1c to the nucleus for the activation of genes involved in lipid metabolism. CONCLUSION Our data suggest that Sar1b expression may promote intestinal lipid transport with the involvement of the coat protein complex II network and the processing of SREBP-1c.
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Affiliation(s)
- Emile Levy
- Research Centre, Mother and Child University Hospital Center, Sainte-Justine, Montreal, Quebec, Canada.
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Calandra S, Tarugi P, Speedy HE, Dean AF, Bertolini S, Shoulders CC. Mechanisms and genetic determinants regulating sterol absorption, circulating LDL levels, and sterol elimination: implications for classification and disease risk. J Lipid Res 2011; 52:1885-926. [PMID: 21862702 DOI: 10.1194/jlr.r017855] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestinal and hepatic-derived lipoprotein remnants (LDLR, APOB, APOE, LDLRAP1, PCSK9, IDOL). The insights gained from integrating the wealth of genetic data with biological processes have important implications for the classification of clinical and presymptomatic diagnoses of traditional LDL dyslipidemias, sitosterolemia, and newly emerging phenotypes, as well as their management through both nutritional and pharmaceutical means.
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Affiliation(s)
- Sebastiano Calandra
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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Georges A, Bonneau J, Bonnefont-Rousselot D, Champigneulle J, Rabès JP, Abifadel M, Aparicio T, Guenedet JC, Bruckert E, Boileau C, Morali A, Varret M, Aggerbeck LP, Samson-Bouma ME. Molecular analysis and intestinal expression of SAR1 genes and proteins in Anderson's disease (Chylomicron retention disease). Orphanet J Rare Dis 2011; 6:1. [PMID: 21235735 PMCID: PMC3029219 DOI: 10.1186/1750-1172-6-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 01/14/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Anderson's disease (AD) or chylomicron retention disease (CMRD) is a very rare hereditary lipid malabsorption syndrome. In order to discover novel mutations in the SAR1B gene and to evaluate the expression, as compared to healthy subjects, of the Sar1 gene and protein paralogues in the intestine, we investigated three previously undescribed individuals with the disease. METHODS The SAR1B, SAR1A and PCSK9 genes were sequenced. The expression of the SAR1B and SAR1A genes in intestinal biopsies of both normal individuals and patients was measured by RTqPCR. Immunohistochemistry using antibodies to recombinant Sar1 protein was used to evaluate the expression and localization of the Sar1 paralogues in the duodenal biopsies. RESULTS Two patients had a novel SAR1B mutation (p.Asp48ThrfsX17). The third patient, who had a previously described SAR1B mutation (p.Leu28ArgfsX7), also had a p.Leu21dup variant of the PCSK9 gene. The expression of the SAR1B gene in duodenal biopsies from an AD/CMRD patient was significantly decreased whereas the expression of the SAR1A gene was significantly increased, as compared to healthy individuals. The Sar1 proteins were present in decreased amounts in enterocytes in duodenal biopsies from the patients as compared to those from healthy subjects. CONCLUSIONS Although the proteins encoded by the SAR1A and SAR1B genes are 90% identical, the increased expression of the SAR1A gene in AD/CMRD does not appear to compensate for the lack of the SAR1B protein. The PCSK9 variant, although reported to be associated with low levels of cholesterol, does not appear to exert any additional effect in this patient. The results provide further insight into the tissue-specific nature of AD/CMRD.
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Affiliation(s)
- Amandine Georges
- Service de Médecine Infantile 3 et Génétique Clinique, INSERM U954, Hôpital d'Enfants Brabois, CHU Nancy, Vandoeuvre les Nancy, 54511, France
| | - Jessica Bonneau
- INSERM U781, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, 75015, France
| | - Dominique Bonnefont-Rousselot
- UF de Biochimie des Maladies Métaboliques, Service de Biochimie Métabolique, Groupe Hospitalier Pitié-Salpêtrière (AP-HP), and Département de Biologie Expérimentale, Métabolique et Clinique, EA 4466, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Paris, 75013, France
| | - Jacqueline Champigneulle
- Laboratoire d'Anatomie et de Cytologie Pathologiques, Hôpital de Brabois, Université Paris 13, Bobigny, 93000, France
| | - Jean P Rabès
- INSERM U781, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, 75015, France
- Service de Biochimie et Génétique Moléculaire, CHU A Paré, AP-HP et Faculté de Médecine (PIFO-UVSQ), Boulogne, 92104, France
| | - Marianne Abifadel
- INSERM U781, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, 75015, France
| | - Thomas Aparicio
- Service de Gastroentérologie, Hôpital Avicenne, 125 rue de Stalingrad, Université Paris 13, Bobigny, 93000, France
| | - Jean C Guenedet
- Laboratoire d'Anatomie et de Cytologie Pathologiques, Hôpital de Brabois, Université Paris 13, Bobigny, 93000, France
- Service de Microscopie Electronique, Hôpital de Brabois, CHU Nancy, Vandoeuvre les Nancy, 54511, France
| | - Eric Bruckert
- Service d'Endocrinologie-Métabolisme, Hôpital Pitié Salpêtrière, (AP-HP), Paris, 75013, France
| | - Catherine Boileau
- INSERM U781, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, 75015, France
- Service de Biochimie et Génétique Moléculaire, CHU A Paré, AP-HP et Faculté de Médecine (PIFO-UVSQ), Boulogne, 92104, France
| | - Alain Morali
- Service de Médecine Infantile 3 et Génétique Clinique, INSERM U954, Hôpital d'Enfants Brabois, CHU Nancy, Vandoeuvre les Nancy, 54511, France
| | - Mathilde Varret
- INSERM U781, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, 75015, France
| | | | - Marie E Samson-Bouma
- INSERM U781, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, 75015, France
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Peretti N, Sassolas A, Roy CC, Deslandres C, Charcosset M, Castagnetti J, Pugnet-Chardon L, Moulin P, Labarge S, Bouthillier L, Lachaux A, Levy E. Guidelines for the diagnosis and management of chylomicron retention disease based on a review of the literature and the experience of two centers. Orphanet J Rare Dis 2010; 5:24. [PMID: 20920215 PMCID: PMC2956717 DOI: 10.1186/1750-1172-5-24] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 09/29/2010] [Indexed: 02/06/2023] Open
Abstract
Familial hypocholesterolemia, namely abetalipoproteinemia, hypobetalipoproteinemia and chylomicron retention disease (CRD), are rare genetic diseases that cause malnutrition, failure to thrive, growth failure and vitamin E deficiency, as well as other complications. Recently, the gene implicated in CRD was identified. The diagnosis is often delayed because symptoms are nonspecific. Treatment and follow-up remain poorly defined. The aim of this paper is to provide guidelines for the diagnosis, treatment and follow-up of children with CRD based on a literature overview and two pediatric centers 'experience. The diagnosis is based on a history of chronic diarrhea with fat malabsorption and abnormal lipid profile. Upper endoscopy and histology reveal fat-laden enterocytes whereas vitamin E deficiency is invariably present. Creatine kinase (CK) is usually elevated and hepatic steatosis is common. Genotyping identifies the Sar1b gene mutation. Treatment should be aimed at preventing potential complications. Vomiting, diarrhea and abdominal distension improve on a low-long chain fat diet. Failure to thrive is one of the most common initial clinical findings. Neurological and ophthalmologic complications in CRD are less severe than in other types of familial hypocholesterolemia. However, the vitamin E deficiency status plays a pivotal role in preventing neurological complications. Essential fatty acid (EFA) deficiency is especially severe early in life. Recently, increased CK levels and cardiomyopathy have been described in addition to muscular manifestations. Poor mineralization and delayed bone maturation do occur. A moderate degree of macrovesicular steatosis is common, but no cases of steatohepatitis cirrhosis. Besides a low-long chain fat diet made up uniquely of polyunsaturated fatty acids, treatment includes fat-soluble vitamin supplements and large amounts of vitamin E. Despite fat malabsorption and the absence of postprandial chylomicrons, the oral route can prevent neurological complications even though serum levels of vitamin E remain chronically low. Dietary counseling is needed not only to monitor fat intake and improve symptoms, but also to maintain sufficient caloric and EFA intake. Despite a better understanding of the pathogenesis of CRD, the diagnosis and management of the disease remain a challenge for clinicians. The clinical guidelines proposed will helpfully lead to an earlier diagnosis and the prevention of complications.
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Affiliation(s)
- Noel Peretti
- Department of Nutrition, CHU Sainte-Justine Research Center, Université de Montréal, 3175, Ste-Catherine Road, Montreal, Quebec, H3T 1C5, Canada
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