1
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Cao C, Liu Y, Liu L, Wang X. Identification of a Compound Heterozygous LMF1 Variants in a Patient with Severe Hypertriglyceridemia - Case Report and Literature Review. J Atheroscler Thromb 2024; 31:1106-1111. [PMID: 38462482 PMCID: PMC11224691 DOI: 10.5551/jat.64697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 01/28/2024] [Indexed: 03/12/2024] Open
Abstract
Familial chylomicronemia syndrome (FCS) and multifactorial chylomicronemia (MCM), characterized by highly variable triglyceride levels with acute episodes of severe hypertriglyceridemia (HTG), are caused by rare variants in genes associated with the catabolism of circulating lipoprotein triglycerides, mainly including LPL, APOC2, APOA5, GPIHBP1, and LMF1. Among them, the LMF1 gene only accounts for 1%. This study described a Chinese patient with severe HTG carrying compound heterozygous variants of a rare nonsense variant p.W168X in exon 3 and a missense variant p.R416Q in exon 9 in the LMF1 gene. These heterozygous variants account for his family's decreased lipase activity and mass, which caused the FCS phenotype.
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Affiliation(s)
- Conghui Cao
- Department of Endocrinology and Metabolism, Institute of Endocrinology, NHC Key Laboratory of Diagnosis and Treatment of
Thyroid Diseases, The First Hospital of China Medical University, Shenyang, P.R. China
| | - Yuqi Liu
- Department of Endocrinology and Metabolism, Institute of Endocrinology, NHC Key Laboratory of Diagnosis and Treatment of
Thyroid Diseases, The First Hospital of China Medical University, Shenyang, P.R. China
| | - Lu Liu
- Department of Endocrinology and Metabolism, Institute of Endocrinology, NHC Key Laboratory of Diagnosis and Treatment of
Thyroid Diseases, The First Hospital of China Medical University, Shenyang, P.R. China
| | - Xiaoli Wang
- Department of Endocrinology and Metabolism, Institute of Endocrinology, NHC Key Laboratory of Diagnosis and Treatment of
Thyroid Diseases, The First Hospital of China Medical University, Shenyang, P.R. China
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2
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Alves M, Laranjeira F, Correia-da-Silva G. Understanding Hypertriglyceridemia: Integrating Genetic Insights. Genes (Basel) 2024; 15:190. [PMID: 38397180 PMCID: PMC10887881 DOI: 10.3390/genes15020190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
Hypertriglyceridemia is an exceptionally complex metabolic disorder characterized by elevated plasma triglycerides associated with an increased risk of acute pancreatitis and cardiovascular diseases such as coronary artery disease. Its phenotype expression is widely heterogeneous and heavily influenced by conditions as obesity, alcohol consumption, or metabolic syndromes. Looking into the genetic underpinnings of hypertriglyceridemia, this review focuses on the genetic variants in LPL, APOA5, APOC2, GPIHBP1 and LMF1 triglyceride-regulating genes reportedly associated with abnormal genetic transcription and the translation of proteins participating in triglyceride-rich lipoprotein metabolism. Hypertriglyceridemia resulting from such genetic abnormalities can be categorized as monogenic or polygenic. Monogenic hypertriglyceridemia, also known as familial chylomicronemia syndrome, is caused by homozygous or compound heterozygous pathogenic variants in the five canonical genes. Polygenic hypertriglyceridemia, also known as multifactorial chylomicronemia syndrome in extreme cases of hypertriglyceridemia, is caused by heterozygous pathogenic genetic variants with variable penetrance affecting the canonical genes, and a set of common non-pathogenic genetic variants (polymorphisms, using the former nomenclature) with well-established association with elevated triglyceride levels. We further address recent progress in triglyceride-lowering treatments. Understanding the genetic basis of hypertriglyceridemia opens new translational opportunities in the scope of genetic screening and the development of novel therapies.
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Affiliation(s)
- Mara Alves
- Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal;
| | - Francisco Laranjeira
- CGM—Centro de Genética Médica Jacinto de Magalhães, Centro Hospitalar Universitário de Santo António (CHUdSA), 4099-028 Porto, Portugal;
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-346 Porto, Portugal
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-600 Porto, Portugal
| | - Georgina Correia-da-Silva
- UCIBIO Applied Molecular Biosciences Unit and Associate Laboratory i4HB—Institute for Health and Bioeconomy Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
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3
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Tanaka M, Takase S, Ishiura H, Yamauchi T, Okazaki S, Okazaki H. A novel homozygous nonsense variant of LMF1 in pregnancy-induced hypertriglyceridemia with acute pancreatitis. J Clin Lipidol 2023; 17:327-331. [PMID: 37005154 DOI: 10.1016/j.jacl.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 03/05/2023] [Accepted: 03/14/2023] [Indexed: 03/29/2023]
Abstract
Hypertriglyceridemia (HTG)-induced pancreatitis during pregnancy could lead to maternal and fetal death. However, its genetic bases are not fully understood, and its treatment strategies are yet to be established. Here we report a case with a novel homozygous nonsense variant of LMF1 in pregnancy-associated HTG with acute pancreatitis. Our patient had childhood-onset severe HTG that had been well-controlled by dietary management in the non-pregnant period with plasma triglyceride (TG) levels at around 200 mg/dL. Milky plasma was noted at the first-trimester pregnancy checkup, followed by a severe increase in plasma TG (10,500 mg/dL) that resulted in pancreatitis in the last trimester. The implementation of strict dietary fat restriction (less than 4 grams per day) reduced plasma TG levels and led to successful delivery. Exome sequencing revealed a novel homozygous nonsense variant in LMF1 (c.697C>T, p.Arg233Ter). The activities of lipoprotein lipase (LPL) and hepatic lipase in post-heparin plasma were not abolished but reduced. The use of pemafibrate decreased plasma TG levels with a concomitant increase in LPL activity. HTG in childhood or early pregnancy is commonly assumed to be polygenic in origin but should be regarded as a feature suggestive of monogenic hyperchylomicronemia. Adequate TG monitoring and dietary fat restriction should be implemented to prevent potentially lethal events of pancreatitis.
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Affiliation(s)
- Masaki Tanaka
- The Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Satoru Takase
- The Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Ishiura
- The Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshimasa Yamauchi
- The Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Sachiko Okazaki
- The Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; The Division for Health Service Promotion, The University of Tokyo, Tokyo, Japan
| | - Hiroaki Okazaki
- The Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; The Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University, Tochigi, Japan.
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4
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Lokmer A, Alladi CG, Troudet R, Bacq-Daian D, Boland-Auge A, Latapie V, Deleuze JF, RajKumar RP, Shewade DG, Bélivier F, Marie-Claire C, Jamain S. Risperidone response in patients with schizophrenia drives DNA methylation changes in immune and neuronal systems. Epigenomics 2023; 15:21-38. [PMID: 36919681 DOI: 10.2217/epi-2023-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
Background: The choice of efficient antipsychotic therapy for schizophrenia relies on a time-consuming trial-and-error approach, whereas the social and economic burdens of the disease call for faster alternatives. Material & methods: In a search for predictive biomarkers of antipsychotic response, blood methylomes of 28 patients were analyzed before and 4 weeks into risperidone therapy. Results: Several CpGs exhibiting response-specific temporal dynamics were identified in otherwise temporally stable methylomes and noticeable global response-related differences were observed between good and bad responders. These were associated with genes involved in immunity, neurotransmission and neuronal development. Polymorphisms in many of these genes were previously linked with schizophrenia etiology and antipsychotic response. Conclusion: Antipsychotic response seems to be shaped by both stable and medication-induced methylation differences.
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Affiliation(s)
- Ana Lokmer
- Univ Paris Est Créteil, INSERM, IMRB, Translational Neuropsychiatry, Créteil, F-94000, France.,Fondation FondaMental, Créteil, F-94000, France
| | - Charanraj Goud Alladi
- Université de Paris, INSERM UMRS 1144, Optimisation Thérapeutique en Neuropsychopharmacologie (OTeN), Paris, F-75006, France
| | - Réjane Troudet
- Univ Paris Est Créteil, INSERM, IMRB, Translational Neuropsychiatry, Créteil, F-94000, France.,Fondation FondaMental, Créteil, F-94000, France
| | - Delphine Bacq-Daian
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, F-91057, France
| | - Anne Boland-Auge
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, F-91057, France
| | - Violaine Latapie
- Univ Paris Est Créteil, INSERM, IMRB, Translational Neuropsychiatry, Créteil, F-94000, France.,Fondation FondaMental, Créteil, F-94000, France
| | - Jean-François Deleuze
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, F-91057, France
| | - Ravi Philip RajKumar
- Department of Pharmacology, Jawaharlal Institute of Postgraduate Medical Education & Research, Puducherry, 605006, India
| | - Deepak Gopal Shewade
- Department of Psychiatry, Jawaharlal Institute of Postgraduate Medical Education & Research, Puducherry, 605006, India.,Centre National de Recherche en Génomique Humaine (CNRGH), Institut de Biologie François Jacob, CEA, Université Paris-Saclay, Evry, F-91000, France
| | - Frank Bélivier
- Fondation FondaMental, Créteil, F-94000, France.,Université de Paris, INSERM UMRS 1144, Optimisation Thérapeutique en Neuropsychopharmacologie (OTeN), Paris, F-75006, France.,Hôpitaux Lariboisière-Fernand Widal, GHU APHP Nord, Département de Psychiatrie et de Médecine Addicto-logique, Paris, F-75010, France
| | - Cynthia Marie-Claire
- Université de Paris, INSERM UMRS 1144, Optimisation Thérapeutique en Neuropsychopharmacologie (OTeN), Paris, F-75006, France
| | - Stéphane Jamain
- Univ Paris Est Créteil, INSERM, IMRB, Translational Neuropsychiatry, Créteil, F-94000, France.,Fondation FondaMental, Créteil, F-94000, France
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5
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Guo D, Zheng Y, Gan Z, Guo Y, Jiang S, Yang F, Xiong F, Zheng H. A Heterozygous LMF1 Gene Mutation (c.1523C>T), Combined With an LPL Gene Mutation (c.590G>A), Aggravates the Clinical Symptoms in Hypertriglyceridemia. Front Genet 2022; 13:814295. [PMID: 35368694 PMCID: PMC8966663 DOI: 10.3389/fgene.2022.814295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 03/01/2022] [Indexed: 11/13/2022] Open
Abstract
Hypertriglyceridemia is an important contributor to atherosclerotic cardiovascular disease (ASCVD) and acute pancreatitis. Familial hypertriglyceridemia is often caused by mutations in genes involved in triglyceride metabolism. Here, we investigated the disease-causing gene mutations in a Chinese family with hypertriglyceridemia and assessed the functional significance in vitro. Whole-exome sequencing (WES) was performed revealing that the severe hypertriglyceridemic proband carried a missense mutation (c.590G > A) in exon 5 of the LPL gene, as well as a missense mutation (c.1523C > T) in exon 10 of the LMF1 gene. Conservation analysis by Polyphen-2 showed that the 508 locus in the LMF1 protein and 197 locus in the LPL protein were highly conserved between different species. I-TASSER analysis indicated that the LMF1 c.1523C > T mutation and the LPL c.590G > A mutation changed the tertiary structure of the protein. A decrease in mRNA and protein expression was observed in 293T cells transfected with plasmids carrying the LMF1 c.1523C > T mutation. Subcellular localization showed that both wild-type (WT) and mutant LMF1 protein were localized at the cell cytoplasm. In the cell medium and cell lysates, these LMF1 and LPL gene mutations both caused a decreased LPL mass. Moreover, the combination of LMF1 and LPL gene mutations significantly decreased LPL levels compared to their individual effects on the LPL concentration. Both the clinical and in vitro data suggest that severe hypertriglyceridemia was of digenic origin caused by LMF1 and LPL mutation double heterozygosity in this patient.
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Affiliation(s)
- Danxia Guo
- Department of Cardiovascular Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yingchun Zheng
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Zhongzhi Gan
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yingying Guo
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Sijie Jiang
- Department of Cardiovascular Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Fang Yang
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Fu Xiong
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- *Correspondence: Fu Xiong, ; Hua Zheng,
| | - Hua Zheng
- Department of Cardiovascular Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
- *Correspondence: Fu Xiong, ; Hua Zheng,
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6
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Garay-García K, Gaete PV, Mendivil CO. Severe hypertriglyceridemia secondary to splice-site and missense variants in LMF1 in three patients from Ecuador. J Clin Lipidol 2022; 16:277-280. [DOI: 10.1016/j.jacl.2022.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/07/2022] [Accepted: 02/14/2022] [Indexed: 12/20/2022]
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7
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The Importance of Lipoprotein Lipase Regulation in Atherosclerosis. Biomedicines 2021; 9:biomedicines9070782. [PMID: 34356847 PMCID: PMC8301479 DOI: 10.3390/biomedicines9070782] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 02/07/2023] Open
Abstract
Lipoprotein lipase (LPL) plays a major role in the lipid homeostasis mainly by mediating the intravascular lipolysis of triglyceride rich lipoproteins. Impaired LPL activity leads to the accumulation of chylomicrons and very low-density lipoproteins (VLDL) in plasma, resulting in hypertriglyceridemia. While low-density lipoprotein cholesterol (LDL-C) is recognized as a primary risk factor for atherosclerosis, hypertriglyceridemia has been shown to be an independent risk factor for cardiovascular disease (CVD) and a residual risk factor in atherosclerosis development. In this review, we focus on the lipolysis machinery and discuss the potential role of triglycerides, remnant particles, and lipolysis mediators in the onset and progression of atherosclerotic cardiovascular disease (ASCVD). This review details a number of important factors involved in the maturation and transportation of LPL to the capillaries, where the triglycerides are hydrolyzed, generating remnant lipoproteins. Moreover, LPL and other factors involved in intravascular lipolysis are also reported to impact the clearance of remnant lipoproteins from plasma and promote lipoprotein retention in capillaries. Apolipoproteins (Apo) and angiopoietin-like proteins (ANGPTLs) play a crucial role in regulating LPL activity and recent insights into LPL regulation may elucidate new pharmacological means to address the challenge of hypertriglyceridemia in atherosclerosis development.
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8
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Okazaki H, Gotoda T, Ogura M, Ishibashi S, Inagaki K, Daida H, Hayashi T, Hori M, Masuda D, Matsuki K, Yokoyama S, Harada-Shiba M. Current Diagnosis and Management of Primary Chylomicronemia. J Atheroscler Thromb 2021; 28:883-904. [PMID: 33980761 PMCID: PMC8532063 DOI: 10.5551/jat.rv17054] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Primary chylomicronemia (PCM) is a rare and intractable disease characterized by marked accumulation of chylomicrons in plasma. The levels of plasma triglycerides (TGs) typically range from 1,000 - 15,000 mg/dL or higher.
PCM is caused by defects in the lipoprotein lipase (LPL) pathway due to genetic mutations, autoantibodies, or unidentified causes. The monogenic type is typically inherited as an autosomal recessive trait with loss-of-function mutations in LPL pathway genes (
LPL
,
LMF1
,
GPIHBP1
,
APOC2
, and
APOA5
). Secondary/environmental factors (diabetes, alcohol intake, pregnancy, etc.) often exacerbate hypertriglyceridemia (HTG).
The signs, symptoms, and complications of chylomicronemia include eruptive xanthomas, lipemia retinalis, hepatosplenomegaly, and acute pancreatitis with onset as early as in infancy. Acute pancreatitis can be fatal and recurrent episodes of abdominal pain may lead to dietary fat intolerance and failure to thrive. The main goal of treatment is to prevent acute pancreatitis by reducing plasma TG levels to at least less than 500-1,000 mg/dL. However, current TG-lowering medications are generally ineffective for PCM. The only other treatment options are modulation of secondary/environmental factors. Most patients need strict dietary fat restriction, which is often difficult to maintain and likely affects their quality of life. Timely diagnosis is critical for the best prognosis with currently available management, but PCM is often misdiagnosed and undertreated. The aim of this review is firstly to summarize the pathogenesis, signs, symptoms, diagnosis, and management of PCM, and secondly to propose simple diagnostic criteria that can be readily translated into general clinical practice to improve the diagnostic rate of PCM. In fact, these criteria are currently used to define eligibility to receive social support from the Japanese government for PCM as a rare and intractable disease. Nevertheless, further research to unravel the molecular pathogenesis and develop effective therapeutic modalities is warranted. Nationwide registry research on PCM is currently ongoing in Japan with the aim of better understanding the disease burden as well as the unmet needs of this life-threatening disease with poor therapeutic options.
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Affiliation(s)
- Hiroaki Okazaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Takanari Gotoda
- Department of Metabolic Biochemistry, Faculty of Medicine, Kyorin University
| | - Masatsune Ogura
- Department of Molecular Innovation in Lipidology, National Cerebral and Cardiovascular Center Research Institute
| | - Shun Ishibashi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, Jichi Medical University
| | - Kyoko Inagaki
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Nippon Medical School
| | - Hiroyuki Daida
- Faculty of Health Science, Juntendo University, Juntendo University Graduate School of Medicine
| | - Toshio Hayashi
- School of Health Sciences, Nagoya University Graduate School of Medicine
| | - Mika Hori
- Department of Endocrinology, Research Institute of Environmental Medicine, Nagoya University
| | - Daisaku Masuda
- Department of Cardiology, Health Care Center, Rinku Innovation Center for Wellness Care and Activities (RICWA), Rinku General Medical Center
| | - Kota Matsuki
- Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine
| | | | - Mariko Harada-Shiba
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center Research Institute
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9
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Serveaux Dancer M, Marmontel O, Wozny AS, Marcais C, Mahl M, Dumont S, Simonet T, Moulin P, Di Filippo M, Charrière S. Involvement of a homozygous exon 6 deletion of LMF1 gene in intermittent severe hypertriglyceridemia. J Clin Lipidol 2020; 14:756-761. [PMID: 33039347 DOI: 10.1016/j.jacl.2020.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 09/10/2020] [Accepted: 09/14/2020] [Indexed: 11/16/2022]
Abstract
Severe hypertriglyceridemia (HTG), characterized by triglycerides (TG) permanently over 10 mmol/L, may correspond to familial chylomicronemia syndrome (FCS), a rare disorder. However, hypertriglyceridemic patients more often present multifactorial chylomicronemia syndrome (MCS), characterized by highly variable TG. A few nonsense variants of LMF1 gene were reported in literature in FCS patients. In this study, we described a woman with an intermittent severe HTG. NGS analysis and the sequencing of a long range PCR product revealed a homozygous deletion of 6507 base pairs in LMF1 gene, c.730-1528_898-3417del, removing exon 6, predicted to create an in-frame deletion of 56 amino acids, p.(Thr244_Gln299del). Despite an exon 6 homozygous deletion of LMF1, the patient's highly variable lipid phenotype was suggestive of MCS diagnosis.
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Affiliation(s)
- Marine Serveaux Dancer
- Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie Moléculaire et Métabolique, Pierre-Bénite Cedex, France
| | - Oriane Marmontel
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Oullins Cedex, France; Hospices Civils de Lyon, Groupement Hospitalier Est, Service de Biochimie et Biologie Moléculaire Grand Est, Bron Cedex, France
| | - Anne-Sophie Wozny
- Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie Moléculaire et Métabolique, Pierre-Bénite Cedex, France
| | - Christophe Marcais
- Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie Moléculaire et Métabolique, Pierre-Bénite Cedex, France; INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Oullins Cedex, France
| | - Muriel Mahl
- Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie Moléculaire et Métabolique, Pierre-Bénite Cedex, France
| | - Sabrina Dumont
- Hospices Civils de Lyon, Groupement Hospitalier Est, Service de Biochimie et Biologie Moléculaire Grand Est, Bron Cedex, France
| | - Thomas Simonet
- Hospices Civils de Lyon, Cellule BioInformatique, Bron Cedex, France
| | - Philippe Moulin
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Oullins Cedex, France; Hospices Civils de Lyon, Hôpital Louis Pradel, Fédération d'endocrinologie, Maladies Métaboliques, Diabète et Nutrition, Bron Cedex, France
| | - Mathilde Di Filippo
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Oullins Cedex, France; Hospices Civils de Lyon, Groupement Hospitalier Est, Service de Biochimie et Biologie Moléculaire Grand Est, Bron Cedex, France
| | - Sybil Charrière
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Oullins Cedex, France; Hospices Civils de Lyon, Hôpital Louis Pradel, Fédération d'endocrinologie, Maladies Métaboliques, Diabète et Nutrition, Bron Cedex, France.
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10
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Plengpanich W, Muanpetch S, Charoen S, Kiateprungvej A, Khovidhunkit W. Genetic and functional studies of the LMF1 gene in Thai patients with severe hypertriglyceridemia. Mol Genet Metab Rep 2020; 23:100576. [PMID: 32190547 PMCID: PMC7068683 DOI: 10.1016/j.ymgmr.2020.100576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 11/23/2022] Open
Abstract
Severe hypertriglyceridemia (HTG) due to chylomicronemia is associated with acute pancreatitis and is related to genetic disturbances in several proteins involved in triglyceride (TG) metabolism. Lipase maturation factor 1 (LMF1) is a protein essential for the maturation of lipoprotein lipase (LPL). In this study, we examined the genetic spectrum of the LMF1 gene among subjects with severe HTG and investigated the functional significance of 6 genetic variants in vitro. All 11 exons of the LMF1 gene were sequenced in 101 Thai subjects with severe HTG. For an in vitro study, we performed site-directed mutagenesis, transient expression in cld cells, and measured LPL protein and LPL activity. We identified 2 common variants [p.(Gly36Asp) and p.(Pro562Arg)] and 12 rare variants [p.(Thr143Met), p.(Asn249Ser), p.(Ala287Val), p.(Met346Val), p.(Thr395Ile), p.(Gly410Arg), p.(Asp433Asn), p.(Asp491Asn), p.(Asn501Tyr), p.(Ala504Val), p.(Arg523His), and p.(Leu563Arg)] in 29 patients. In vitro study of the p.(Gly36Asp), p.(Asn249Ser), p.(Ala287Val), p.(Asn501Tyr), p.(Pro562Arg) and p.(Leu563Arg) variants, however, revealed that both LPL mass and LPL activity in each of the transfected cells were not significantly different from those in the wild type LMF1 transfected cells, suggesting that these variants might not play a significant role in severe HTG phenotype in our subjects. Among 101 subjects with severe hypertriglyceridemia (HTG), 2 common and 12 rare variants in the LMF1 gene were identified None of the 6 missense variants studied were associated with a reduction in lipoprotein mass or activity These rare variants in the LMF1 gene may not play an important role in severe HTG phenotypes in the Thai population
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Affiliation(s)
- Wanee Plengpanich
- Endocrinology and Metabolism Unit, Department of Medicine and Hormonal and Metabolic Disorders Research Unit, Faculty of Medicine, Chulalongkorn University, Excellence Center in Diabetes, Hormone, and Metabolism, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Patumwan, Bangkok 10330, Thailand
| | - Suwanna Muanpetch
- Endocrinology and Metabolism Unit, Department of Medicine and Hormonal and Metabolic Disorders Research Unit, Faculty of Medicine, Chulalongkorn University, Excellence Center in Diabetes, Hormone, and Metabolism, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Patumwan, Bangkok 10330, Thailand
| | - Supannika Charoen
- Endocrinology and Metabolism Unit, Department of Medicine and Hormonal and Metabolic Disorders Research Unit, Faculty of Medicine, Chulalongkorn University, Excellence Center in Diabetes, Hormone, and Metabolism, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Patumwan, Bangkok 10330, Thailand
| | - Arunrat Kiateprungvej
- Endocrinology and Metabolism Unit, Department of Medicine and Hormonal and Metabolic Disorders Research Unit, Faculty of Medicine, Chulalongkorn University, Excellence Center in Diabetes, Hormone, and Metabolism, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Patumwan, Bangkok 10330, Thailand
| | - Weerapan Khovidhunkit
- Endocrinology and Metabolism Unit, Department of Medicine and Hormonal and Metabolic Disorders Research Unit, Faculty of Medicine, Chulalongkorn University, Excellence Center in Diabetes, Hormone, and Metabolism, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Patumwan, Bangkok 10330, Thailand
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11
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Basu D, Bornfeldt KE. Hypertriglyceridemia and Atherosclerosis: Using Human Research to Guide Mechanistic Studies in Animal Models. Front Endocrinol (Lausanne) 2020; 11:504. [PMID: 32849290 PMCID: PMC7423973 DOI: 10.3389/fendo.2020.00504] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 06/23/2020] [Indexed: 12/18/2022] Open
Abstract
Human studies support a strong association between hypertriglyceridemia and atherosclerotic cardiovascular disease (CVD). However, whether a causal relationship exists between hypertriglyceridemia and increased CVD risk is still unclear. One plausible explanation for the difficulty establishing a clear causal role for hypertriglyceridemia in CVD risk is that lipolysis products of triglyceride-rich lipoproteins (TRLs), rather than the TRLs themselves, are the likely mediators of increased CVD risk. This hypothesis is supported by studies of rare mutations in humans resulting in impaired clearance of such lipolysis products (remnant lipoprotein particles; RLPs). Several animal models of hypertriglyceridemia support this hypothesis and have provided additional mechanistic understanding. Mice deficient in lipoprotein lipase (LPL), the major vascular enzyme responsible for TRL lipolysis and generation of RLPs, or its endothelial anchor GPIHBP1, are severely hypertriglyceridemic but develop only minimal atherosclerosis as compared with animal models deficient in apolipoprotein (APO) E, which is required to clear TRLs and RLPs. Likewise, animal models convincingly show that increased clearance of TRLs and RLPs by LPL activation (achieved by inhibition of APOC3, ANGPTL3, or ANGPTL4 action, or increased APOA5) results in protection from atherosclerosis. Mechanistic studies suggest that RLPs are more atherogenic than large TRLs because they more readily enter the artery wall, and because they are enriched in cholesterol relative to triglycerides, which promotes pro-atherogenic effects in lesional cells. Other mechanistic studies show that hepatic receptors (LDLR and LRP1) and APOE are critical for RLP clearance. Thus, studies in animal models have provided additional mechanistic insight and generally agree with the hypothesis that RLPs derived from TRLs are highly atherogenic whereas hypertriglyceridemia due to accumulation of very large TRLs in plasma is not markedly atherogenic in the absence of TRL lipolysis products.
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Affiliation(s)
- Debapriya Basu
- Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY, United States
| | - Karin E. Bornfeldt
- Department of Medicine, University of Washington Medicine Diabetes Institute, University of Washington School of Medicine, Seattle, WA, United States
- Department of Pathology, University of Washington Medicine Diabetes Institute, University of Washington School of Medicine, Seattle, WA, United States
- *Correspondence: Karin E. Bornfeldt
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12
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Ariza MJ, Rioja J, Ibarretxe D, Camacho A, Díaz-Díaz JL, Mangas A, Carbayo-Herencia JA, Ruiz-Ocaña P, Lamíquiz-Moneo I, Mosquera D, Sáenz P, Masana L, Muñiz-Grijalvo O, Pérez-Calahorra S, Valdivielso P, Suárez Tembra M, Iglesias GP, Carbayo Herencia J, Guerrero Buitrago C, Vila L, Morales Coca C, Llargués Rocabruna E, Perea Castillo V, Pedro-Botet J, Climent E, Mauri Pont M, Pinto X, Ortega Martínez de la Victoria E, Amor J, Zambón Rados D, Blanco Vaca F, Ramiro Lozano J, Fuentes Jiménez F, Soler I, Ferrer C, Zamora Cervantes A, Vila Belmonte A, Novoa Mogollón F, Sanchez-Hernández R, Expósito Montesdeoca A, Romero Jiménez M, González García M, Bueno Díez M, Brea Hernando A, Lahoz C, Mostaza Prieto J, Millán Núñez-Cortés J, Reinares García L, Blanco Echevarría A, Ariza Corbo MJ, Rioja Villodres J, Sánchez-Chaparro M, Jansen Chaparro S, Sáenz Aranzubía P, Martorell Mateu E, Almagro Múgica F, Muñiz Grijalvo O, Masana Martín L, Plana Gil N, Ibarretxe Gerediaga D, Rodríguez Borjabad C, Zabala López S, Hernández Mijares A, Ascaso Gimilio J, Pérez García L, Civeira Murillo F, Pérez-Calahorra S, Lamiquiz-Moneo I, Mateo Gallego R, Marco Benedí V, Ferrando Vela J. Molecular basis of the familial chylomicronemia syndrome in patients from the National Dyslipidemia Registry of the Spanish Atherosclerosis Society. J Clin Lipidol 2018; 12:1482-1492.e3. [DOI: 10.1016/j.jacl.2018.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/09/2018] [Accepted: 07/24/2018] [Indexed: 01/16/2023]
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13
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Péterfy M, Bedoya C, Giacobbe C, Pagano C, Gentile M, Rubba P, Fortunato G, Di Taranto MD. Characterization of two novel pathogenic variants at compound heterozygous status in lipase maturation factor 1 gene causing severe hypertriglyceridemia. J Clin Lipidol 2018; 12:1253-1259. [PMID: 30172716 DOI: 10.1016/j.jacl.2018.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/07/2018] [Accepted: 07/13/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND Severe hypertriglyceridemia is a rare disease characterized by triglyceride levels higher than 1000 mg/dL (11.3 mmol/L) and acute pancreatitis. The disease is caused by pathogenic variants in genes encoding lipoprotein lipase (LPL), apolipoprotein A5, apolipoprotein C2, glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1, and lipase maturation factor 1 (LMF1). OBJECTIVE We aim to identify the genetic cause of severe hypertriglyceridemia and characterize the new variants in a patient with severe hypertriglyceridemia. METHODS The proband was a male showing severe hypertriglyceridemia (triglycerides 1416 mg/dL, 16.0 mmol/L); proband's relatives were also screened. Genetic screening included direct sequencing of the above genes and identification of large rearrangements in the LPL gene. Functional characterization of mutant LMF1 variants was performed by complementing LPL maturation in transfected LMF1-deficient mouse fibroblasts. RESULTS The proband and his affected brother were compound heterozygotes for variants in the LMF1 gene never identified as causative of severe hypertriglyceridemia c.[157delC;1351C>T];[410C>T], p.[(Arg53Glyfs*5)];[(Ser137Leu)]. Functional analysis demonstrated that the p.(Arg53Glyfs*5) truncation completely abolished and the p.(Ser137Leu) missense variant dramatically diminished the lipase maturation activity of LMF1. CONCLUSIONS In addition to a novel truncating variant, we describe for the first time a missense variant functionally demonstrated affecting the lipase maturation function of LMF1. This is the first case in which compound heterozygous variants in LMF1 were functionally demonstrated as causative of severe hypertriglyceridemia.
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Affiliation(s)
- Miklós Péterfy
- Department of Basic Medical Sciences, Western University of Health Sciences, Pomona, CA, USA; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Candy Bedoya
- Department of Basic Medical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Carola Giacobbe
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli, Italy; CEINGE S.C.a r.l. Biotecnologie Avanzate, Napoli, Italy
| | - Carmen Pagano
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy
| | - Marco Gentile
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy
| | - Paolo Rubba
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy
| | - Giuliana Fortunato
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli, Italy; CEINGE S.C.a r.l. Biotecnologie Avanzate, Napoli, Italy
| | - Maria Donata Di Taranto
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli, Italy; CEINGE S.C.a r.l. Biotecnologie Avanzate, Napoli, Italy.
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14
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Roberts BS, Babilonia-Rosa MA, Broadwell LJ, Wu MJ, Neher SB. Lipase maturation factor 1 affects redox homeostasis in the endoplasmic reticulum. EMBO J 2018; 37:embj.201797379. [PMID: 30068531 DOI: 10.15252/embj.201797379] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 06/18/2018] [Accepted: 06/20/2018] [Indexed: 11/09/2022] Open
Abstract
Lipoprotein lipase (LPL) is a secreted lipase that clears triglycerides from the blood. Proper LPL folding and exit from the endoplasmic reticulum (ER) require lipase maturation factor 1 (LMF1), an ER-resident transmembrane protein, but the mechanism involved is unknown. We used proteomics to identify LMF1-binding partners necessary for LPL secretion in HEK293 cells and found these to include oxidoreductases and lectin chaperones, suggesting that LMF1 facilitates the formation of LPL's five disulfide bonds. In accordance with this role, we found that LPL aggregates in LMF1-deficient cells due to the formation of incorrect intermolecular disulfide bonds. Cells lacking LMF1 were hypersensitive to depletion of glutathione, but not DTT treatment, suggesting that LMF1 helps reduce the ER Accordingly, we found that loss of LMF1 results in a more oxidized ER Our data show that LMF1 has a broader role than simply folding lipases, and we identified fibronectin and the low-density lipoprotein receptor (LDLR) as novel LMF1 clients that contain multiple, non-sequential disulfide bonds. We conclude that LMF1 is needed for secretion of some ER client proteins that require reduction of non-native disulfides during their folding.
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Affiliation(s)
- Benjamin S Roberts
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Melissa A Babilonia-Rosa
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lindsey J Broadwell
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ming Jing Wu
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Saskia B Neher
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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15
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Serveaux Dancer M, Di Filippo M, Marmontel O, Valéro R, Piombo Rivarola MDC, Peretti N, Caussy C, Krempf M, Vergès B, Mahl M, Marçais C, Moulin P, Charrière S. New rare genetic variants of LMF1 gene identified in severe hypertriglyceridemia. J Clin Lipidol 2018; 12:1244-1252. [PMID: 30037590 DOI: 10.1016/j.jacl.2018.06.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/20/2018] [Accepted: 06/28/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND The LMF1 (lipase maturation factor 1) gene encodes a protein involved in lipoprotein lipase and hepatic lipase maturation. Homozygous mutations in LMF1 leading to severe hypertriglyceridemia (SHTG) are rare in the literature. A few additional rare LMF1 variants have been described with poor functional studies. OBJECTIVE The aim of this study was to assess the frequency of LMF1 variants in a cohort of 385 patients with SHTG, without homozygous or compound heterozygous deleterious mutations identified in lipoprotein lipase (LPL), apolipoprotein A5 (APOA5), apolipoprotein C2 (APOC2), glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1) genes, and to determine their functionality. METHODS LMF1 coding variants were screened using denaturing high-performance liquid chromatography followed by direct sequencing. In silico studies of LMF1 variants were performed, followed by in vitro functional studies using human embryonic kidney 293T (HEK-293T) cells cotransfected with vectors encoding human LPL and LMF1 cDNA. LPL activity was measured in cell culture medium after heparin addition using human VLDL-TG as substrate. RESULTS Nineteen nonsynonymous coding LMF1 variants were identified in 65 patients; 10 variants were newly described in SHTG. In vitro, p.Gly172Arg, p.Arg354Trp, p.Arg364Gln, and p.Arg537Trp LMF1 variants decreased LPL activity, and the p.Trp464Ter variant completely abolished LPL activity. We identified a young girl heterozygote for the p.Trp464Ter variant and a homozygote carrier of the p.Gly172Arg variant with a near 50% decreased LPL activity in vitro and in vivo. CONCLUSION The study confirms the rarity of LMF1 variants in a large cohort of patients with SHTG. LMF1 variants are likely to be involved in multifactorial hyperchylomicronemia. Partial LMF1 defects could be associated with intermittent phenotype as described for p.Gly172Arg homozygous and p.Trp464Ter heterozygous carriers.
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Affiliation(s)
- Marine Serveaux Dancer
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie moléculaire et métabolique, Pierre-Bénite, France
| | - Mathilde Di Filippo
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Service de Biochimie et Biologie moléculaire Grand Est, Hospices Civils de Lyon, Groupement Hospitalier Est, Bron, France
| | - Oriane Marmontel
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Service de Biochimie et Biologie moléculaire Grand Est, Hospices Civils de Lyon, Groupement Hospitalier Est, Bron, France
| | - René Valéro
- Université d'Aix-Marseille, C2VN, INSERM UMR1062, INRA UMR1260, APHM, service de nutrition, maladies métaboliques, endocrinologie Hôpital La Conception, Marseille, France
| | | | - Noël Peretti
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Hôpital Femme Mère Enfant, Service d'Hépato-Gastroentérologie Nutrition pédiatrique, Bron, France
| | - Cyrielle Caussy
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Hôpital Lyon Sud, Service d'endocrinologie, diabète, nutrition, Centre Intégré de l'Obésité Rhône-Alpes, Fédération Hospitalo-Universitaire DO-iT, Lyon, Pierre-Bénite, France
| | - Michel Krempf
- CHU de Nantes, Hôpital de l'Hôtel Dieu, Service d'endocrinologie, maladies métaboliques et nutrition, Institut du thorax, Centre de Recherche en Nutrition Humaine, INRA, UMR 1280, Physiologie des Adaptations Nutritionnelles, Nantes, France
| | - Bruno Vergès
- CHU de Dijon, Service d'endocrinologie-diabétologie, INSERM LNC-UMR 1231, Dijon, France
| | - Murielle Mahl
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie moléculaire et métabolique, Pierre-Bénite, France
| | - Christophe Marçais
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Centre de Biologie Sud, Laboratoire de Biochimie moléculaire et métabolique, Pierre-Bénite, France
| | - Philippe Moulin
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Hôpital Louis Pradel, Fédération d'endocrinologie, maladies métaboliques, diabète et nutrition, Bron, France
| | - Sybil Charrière
- INSERM U1060, Laboratoire Carmen, Université Lyon 1, INRA U1235, INSA de Lyon, CENS, Centre de Recherche en Nutrition Humaine Rhône Alpes, Villeurbanne, Oullins, France; Hospices Civils de Lyon, Hôpital Louis Pradel, Fédération d'endocrinologie, maladies métaboliques, diabète et nutrition, Bron, France.
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16
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Liu Y, Xu J, Tao W, Yu R, Zhang X. A Compound Heterozygous Mutation of Lipase Maturation Factor 1 is Responsible for Hypertriglyceridemia of a Patient. J Atheroscler Thromb 2018; 26:136-144. [PMID: 29910226 PMCID: PMC6365152 DOI: 10.5551/jat.44537] [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] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
AIM Dyslipidemia is the most common lipid metabolism disorder in humans, and its etiology remains elusive. Hypertriglyceridemia (HTG) is a type of dyslipidemia that contributes to atherosclerosis and coronary heart disease. Previous studies have demonstrated that mutations in lipoprotein lipase (LPL), apolipoprotein CII (APOC2), apolipoprotein AV (APOA5), glycosylphosphatidylinositol anchored high-density lipoprotein-binding protein 1 (GPIHBP1), lipase maturation factor 1(LMF1), and glycerol-3 phosphate dehydrogenase 1 (GPD1) are responsible for HTG by using genomic microarrays and next-generation sequencing. The aim of this study was to identify genetic lesions in patients with HTG. METHOD Our study included a family of seven members from Jiangsu province across three generations. The proband was diagnosed with severe HTG, with a plasma triglyceride level of 38.70 mmol/L. Polymerase chain reaction (PCR) and Sanger sequencing were performed to explore the possible causative gene mutations for this patient. Furthermore, we measured the post-heparin LPL and hepatic lipase (HL) activities using an antiserum inhibition method. RESULTS A compound heterozygous mutation in the LMF1 gene (c.257C>T/p.P86L and c.1184C>T/p.T395I) was identified and co-segregated with the affected patient in this family. Both mutations were predicted to be deleterious by three bioinformatics programs (Polymorphism Phenotyping-2, Sorting Intolerant From Tolerant, and MutationTaster). The levels of the plasma post-heparin LPL and HL activities in the proband (57 and 177 mU/mL) were reduced to 24% and 75%, respectively, compared with those assayed in the control subject with normal plasma triglycerides. CONCLUSION A compound heterozygous mutation of LMF1 was identified in the presenting patient with severe HTG. These findings expand on the spectrum of LMF1 mutations and contribute to the genetic diagnosis and counseling of families with HTG.
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Affiliation(s)
- Yihui Liu
- Department of Neurology, Affiliated Hospital of Yangzhou University
| | - Jiang Xu
- Medical School of Yangzhou University
| | - Wanyun Tao
- Department of Biochemistry, School of Medicine, Case Western Reserve University
| | - Rong Yu
- Department of Anesthesiology, the Second XiangYa Hospital, Central South University
| | - Xinjiang Zhang
- Department of Neurology, Affiliated Hospital of Yangzhou University.,Medical School of Yangzhou University
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17
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Li JJ, Chen YQ, Fan LL, Jin JY, Guo S, Xiang R. Microduplication of 10q26.3 in a Chinese hypertriglyceridemia patient. Mol Cell Probes 2017; 37:28-31. [PMID: 29129660 DOI: 10.1016/j.mcp.2017.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 11/06/2017] [Accepted: 11/06/2017] [Indexed: 10/18/2022]
Abstract
Hypertriglyceridemia (HTG) plays an important role in the development and progression of atherosclerosis. It is inherited in an autosomal dominant pattern with a frequency of approximately 1:1,000,000 worldwide. Previous study has demonstrated that more than six genes underlie this disorder. In addition, copy number variants (CNVs) including disease-causing genes also play a crucial role in it. In this study, we have employed SNP-ARRAY chip technology to detect the pathogenic CNVs in a HTG patient who carried no meaningful mutations in HTG candidate genes. And we identified a de novo CNV interstitial 134.7 kb duplication of chromosome region 10q26.3 containing CYP2E1. And this CNV also has been confirmed by Real-time PCR. CYP2E1 is a member of cytochrome P450 superfamily of enzymes which play an important role in fatty acid metabolism. Our study is consistent with previous research and further claimes that CNVs containing CYP2E1 may be related to HTG and obesity. Our study not only further confirmes the hypothesis that the CYP2E1 is a plausible candidate gene for HTG, but also may contribute to the diagnosis and treatment of these genomic diseases.
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Affiliation(s)
- Jing-Jing Li
- The State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China
| | - Ya-Qin Chen
- The Second Xiangya Hospital of Central South University, Changsha 410013, China
| | - Liang-Liang Fan
- The State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China
| | - Jie-Yuan Jin
- The State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China
| | - Shuai Guo
- The State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China
| | - Rong Xiang
- The State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China; The Second Xiangya Hospital of Central South University, Changsha 410013, China.
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18
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Severe hypertriglyceridemia in Japan: Differences in causes and therapeutic responses. J Clin Lipidol 2017; 11:1383-1392. [PMID: 28958672 DOI: 10.1016/j.jacl.2017.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 07/27/2017] [Accepted: 08/10/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND Severe hypertriglyceridemia (>1000 mg/dL) has a variety of causes and frequently leads to life-threating acute pancreatitis. However, the origins of this disorder are unclear for many patients. OBJECTIVE We aimed to characterize the causes of and responses to therapy in rare cases of severe hypertriglyceridemia in a group of Japanese patients. METHODS We enrolled 121 patients from a series of case studies that spanned 30 years. Subjects were divided into 3 groups: (1) primary (genetic causes); (2) secondary (acquired); and (3) disorders of uncertain causes. In the last group, we focused on 3 possible risks factors for hypertriglyceridemia: obesity, diabetes mellitus, and heavy alcohol intake. RESULTS Group A (n = 20) included 13 patients with familial lipoprotein lipase deficiency, 3 patients with apolipoprotein CII deficiency, and other genetic disorders in the rest of the group. Group B patients (n = 15) had various metabolic and endocrine diseases. In Group C (uncertain causes; n = 86), there was conspicuous gender imbalance (79 males, 3 females) and most male subjects were heavy alcohol drinkers. In addition, 18 of 105 adult patients (17%) had histories of acute pancreatitis. CONCLUSION The cause of severe hypertriglyceridemia is uncertain in many patients. In primary genetic forms of severe hypertriglyceridemia, genetic diversity between populations is unknown. In the acquired forms, we found fewer cases of estrogen-induced hypertriglyceridemia than in Western countries. In our clinical experience, the cause of most hypertriglyceridemia is uncertain. Our work suggests that genetic factors for plasma triglyceride sensitivity to alcohol should be explored.
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19
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Ram R, Wakil S, Muiya N, Andres E, Mazhar N, Hagos S, Alshahid M, Meyer B, Morahan G, Dzimiri N. A common variant association study in ethnic Saudi Arabs reveals novel susceptibility loci for hypertriglyceridemia. Clin Genet 2017; 91:371-378. [DOI: 10.1111/cge.12859] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/30/2016] [Accepted: 08/30/2016] [Indexed: 12/15/2022]
Affiliation(s)
- R. Ram
- Centre for Diabetes Research, The Harry Perkinsn Institute for Medical Research Perth WA Australia
- Centre for Medical ResearchUniversity of Western Australia Perth WA Australia
| | - S.M. Wakil
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - N.P. Muiya
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - E. Andres
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - N. Mazhar
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - S. Hagos
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - M. Alshahid
- King Faisal Heart InstituteKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - B.F. Meyer
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - G. Morahan
- Centre for Diabetes Research, The Harry Perkinsn Institute for Medical Research Perth WA Australia
- Centre for Medical ResearchUniversity of Western Australia Perth WA Australia
| | - N. Dzimiri
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
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20
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Cefalù AB, Spina R, Noto D, Ingrassia V, Valenti V, Giammanco A, Fayer F, Misiano G, Cocorullo G, Scrimali C, Palesano O, Altieri GI, Ganci A, Barbagallo CM, Averna MR. Identification of a novel LMF1 nonsense mutation responsible for severe hypertriglyceridemia by targeted next-generation sequencing. J Clin Lipidol 2017; 11:272-281.e8. [PMID: 28391895 DOI: 10.1016/j.jacl.2017.01.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 12/28/2016] [Accepted: 01/02/2017] [Indexed: 11/19/2022]
Abstract
BACKGROUND Severe hypertriglyceridemia (HTG) may result from mutations in genes affecting the intravascular lipolysis of triglyceride (TG)-rich lipoproteins. OBJECTIVE The aim of this study was to develop a targeted next-generation sequencing panel for the molecular diagnosis of disorders characterized by severe HTG. METHODS We developed a targeted customized panel for next-generation sequencing Ion Torrent Personal Genome Machine to capture the coding exons and intron/exon boundaries of 18 genes affecting the main pathways of TG synthesis and metabolism. We sequenced 11 samples of patients with severe HTG (TG>885 mg/dL-10 mmol/L): 4 positive controls in whom pathogenic mutations had previously been identified by Sanger sequencing and 7 patients in whom the molecular defect was still unknown. RESULTS The customized panel was accurate, and it allowed to confirm genetic variants previously identified in all positive controls with primary severe HTG. Only 1 patient of 7 with HTG was found to be carrier of a homozygous pathogenic mutation of the third novel mutation of LMF1 gene (c.1380C>G-p.Y460X). The clinical and molecular familial cascade screening allowed the identification of 2 additional affected siblings and 7 heterozygous carriers of the mutation. CONCLUSIONS We showed that our targeted resequencing approach for genetic diagnosis of severe HTG appears to be accurate, less time consuming, and more economical compared with traditional Sanger resequencing. The identification of pathogenic mutations in candidate genes remains challenging and clinical resequencing should mainly intended for patients with strong clinical criteria for monogenic severe HTG.
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Affiliation(s)
- Angelo B Cefalù
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy; Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy.
| | - Rossella Spina
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy; Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy
| | - Davide Noto
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Valeria Ingrassia
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy; Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy
| | - Vincenza Valenti
- Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy
| | - Antonina Giammanco
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Francesca Fayer
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Gabriella Misiano
- Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy
| | - Gianfranco Cocorullo
- Unit of Emergency and General Surgery, Department of Surgical Oncological and Stomatological Sciences, University of Palermo, Palermo, Italy
| | - Chiara Scrimali
- Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy
| | - Ornella Palesano
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Grazia I Altieri
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Antonina Ganci
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Carlo M Barbagallo
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy
| | - Maurizio R Averna
- Dipartimento Biomedico di Medicina Interna e Specialistica (DIBIMIS), University of Palermo, Palermo, Italy; Molecular Biology Diagnostic Laboratory, Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), AOUP "Paolo Giaccone", Palermo, Italy.
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21
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Viecili PRN, da Silva B, Hirsch GE, Porto FG, Parisi MM, Castanho AR, Wender M, Klafke JZ. Triglycerides Revisited to the Serial. Adv Clin Chem 2017; 80:1-44. [PMID: 28431638 DOI: 10.1016/bs.acc.2016.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review discusses the role of triglycerides (TGs) in the normal cardiovascular system as well as in the development and clinical manifestation of cardiovascular diseases. Regulation of TGs at the enzymatic and genetic level, in addition to their possible relevance as preclinical and clinical biomarkers, is discussed, culminating with a description of available and emerging treatments. Due to the high complexity of the subject and the vast amount of material in the literature, the objective of this review was not to exhaust the subject, but rather to compile the information to facilitate and improve the understanding of those interested in this topic. The main publications on the topic were sought out, especially those from the last 5 years. The data in the literature still give reason to believe that there is room for doubt regarding the use of TG as disease biomarkers; however, there is increasing evidence for the role of hypertriglyceridemia on the atherosclerotic inflammatory process, cardiovascular outcomes, and mortality.
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22
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Blanchard PG, Turcotte V, Côté M, Gélinas Y, Nilsson S, Olivecrona G, Deshaies Y, Festuccia WT. Peroxisome proliferator-activated receptor γ activation favours selective subcutaneous lipid deposition by coordinately regulating lipoprotein lipase modulators, fatty acid transporters and lipogenic enzymes. Acta Physiol (Oxf) 2016; 217:227-39. [PMID: 26918671 DOI: 10.1111/apha.12665] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 10/15/2015] [Accepted: 02/19/2016] [Indexed: 12/18/2022]
Abstract
AIM Peroxisome proliferator-activated receptor (PPAR) γ activation is associated with preferential lipoprotein lipase (LPL)-mediated fatty acid storage in peripheral subcutaneous fat depots. How PPARγ agonism acts upon the multi-level modulation of depot-specific lipid storage remains incompletely understood. METHODS We evaluated herein triglyceride-derived lipid incorporation into adipose tissue depots, LPL mass and activity, mRNA levels and content of proteins involved in the modulation of LPL activity and fatty acid transport, and the expression/activity of enzymes defining adipose tissue lipogenic potential in rats treated with the PPARγ ligand rosiglitazone (30 mg kg(-1) day(-1) , 23 days) after either a 10-h fasting period or a 17-h fast followed by 6 h of ad libitum refeeding. RESULTS Rosiglitazone stimulated lipid accretion in subcutaneous fat (SF) ~twofold and significantly reduced that of visceral fat (VF) to nearly half. PPARγ activation selectively increased LPL mass, activity and the expression of its chaperone LMF1 in SF. In VF, rosiglitazone had no effect on LPL activity and downregulated the mRNA levels of the transendothelial transporter GPIHBP1. Overexpression of lipid uptake and fatty acid transport proteins (FAT/CD36, FATP1 and FABP4) and stimulation of lipogenic enzyme activities (GPAT, AGPAT and DGAT) upon rosiglitazone treatment were of higher magnitude in SF. CONCLUSIONS Together these findings demonstrate that the depot-specific transcriptional control of LPL induced by PPARγ activation extends to its key interacting proteins and post-translational modulators to favour subcutaneous lipid storage.
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Affiliation(s)
- P. G. Blanchard
- Department of Medicine; Faculty of Medicine; Quebec Heart and Lung Institute; Laval University; Quebec QC Canada
| | - V. Turcotte
- Department of Medicine; Faculty of Medicine; Quebec Heart and Lung Institute; Laval University; Quebec QC Canada
| | - M. Côté
- Department of Medicine; Faculty of Medicine; Quebec Heart and Lung Institute; Laval University; Quebec QC Canada
| | - Y. Gélinas
- Department of Medicine; Faculty of Medicine; Quebec Heart and Lung Institute; Laval University; Quebec QC Canada
| | - S. Nilsson
- Department of Medical Biosciences/Physiological Chemistry; Umeå University; Umeå Sweden
| | - G. Olivecrona
- Department of Medical Biosciences/Physiological Chemistry; Umeå University; Umeå Sweden
| | - Y. Deshaies
- Department of Medicine; Faculty of Medicine; Quebec Heart and Lung Institute; Laval University; Quebec QC Canada
| | - W. T. Festuccia
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
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23
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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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Valdivielso P. [Hypertriglyceridemia and LMF 1: Another piece of the puzzle]. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS : PUBLICACION OFICIAL DE LA SOCIEDAD ESPANOLA DE ARTERIOSCLEROSIS 2015; 27:253-255. [PMID: 26398545 DOI: 10.1016/j.arteri.2015.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 06/05/2023]
Affiliation(s)
- Pedro Valdivielso
- Unidad de Lípidos, Hospital Virgen de la Victoria,, Málaga, España; Departamento de Medicina y Dermatología, Instituto de Biomedicina de Málaga (IBIMA), Universidad de Málaga, Málaga, España.
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25
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Lamiquiz-Moneo I, Bea AM, Mateo-Gallego R, Baila-Rueda L, Cenarro A, Pocoví M, Civeira F, de Castro-Orós I. [Identification of variants in LMF1 gene associated with primary hypertriglyceridemia]. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS : PUBLICACION OFICIAL DE LA SOCIEDAD ESPANOLA DE ARTERIOSCLEROSIS 2015; 27:246-252. [PMID: 25817768 DOI: 10.1016/j.arteri.2015.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 06/04/2023]
Abstract
The majority of severe primary hypertriglyceridemia (HTG) are diagnosed in adults, and their molecular bases have not yet been fully defined. The promoter, coding regions and intron-exon boundaries of LMF1 were sequenced in 112 patients with severe primary hipertrigliceridemia (defined as TG above 500mg/dl). Five patients (4.46%) were carriers of four rare variants in the LMF1 gene associated with HTG, which participate in lipoprotein lipase (LpL) function. Also, we have identified two common variants, c.194-28 T>G and c.729+18C>G that were associated with HTG, with a different allelic frequency to that observed in the general population. A bioinformatic analysis of all found variants was conducted, defining the following as potentially harmful: p.Arg364Gln, p.Arg451Trp, p.Pro562Arg and p.Leu85Leu. Our results suggest that LMF1 mutations are involved in a substantial proportion of cases with severe HTG, putting together the moderate-aggressive effect of rare mutations with polymorphisms classically associated with this disease.
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Affiliation(s)
- Itziar Lamiquiz-Moneo
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España.
| | - Ana M Bea
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
| | - Rocío Mateo-Gallego
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
| | - Lucía Baila-Rueda
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
| | - Ana Cenarro
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
| | - Miguel Pocoví
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
| | - Fernando Civeira
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
| | - Isabel de Castro-Orós
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, España
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Mao HZ, Ehrhardt N, Bedoya C, Gomez JA, DeZwaan-McCabe D, Mungrue IN, Kaufman RJ, Rutkowski DT, Péterfy M. Lipase maturation factor 1 (lmf1) is induced by endoplasmic reticulum stress through activating transcription factor 6α (Atf6α) signaling. J Biol Chem 2014; 289:24417-27. [PMID: 25035425 PMCID: PMC4148868 DOI: 10.1074/jbc.m114.588764] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Indexed: 11/06/2022] Open
Abstract
Lipase maturation factor 1 (Lmf1) is a critical determinant of plasma lipid metabolism, as demonstrated by severe hypertriglyceridemia associated with its mutations in mice and human subjects. Lmf1 is a chaperone localized to the endoplasmic reticulum (ER) and required for the post-translational maturation and activation of several vascular lipases. Despite its importance in plasma lipid homeostasis, the regulation of Lmf1 remains unexplored. We report here that Lmf1 expression is induced by ER stress in various cell lines and in tunicamycin (TM)-injected mice. Using genetic deficiencies in mouse embryonic fibroblasts and mouse liver, we identified the Atf6α arm of the unfolded protein response as being responsible for the up-regulation of Lmf1 in ER stress. Experiments with luciferase reporter constructs indicated that ER stress activates the Lmf1 promoter through a GC-rich DNA sequence 264 bp upstream of the transcriptional start site. We demonstrated that Atf6α is sufficient to induce the Lmf1 promoter in the absence of ER stress, and this effect is mediated by the TM-responsive cis-regulatory element. Conversely, Atf6α deficiency induced by genetic ablation or a dominant-negative form of Atf6α abolished TM stimulation of the Lmf1 promoter. In conclusion, our results indicate that Lmf1 is an unfolded protein response target gene, and Atf6α signaling is sufficient and necessary for activation of the Lmf1 promoter. Importantly, the induction of Lmf1 by ER stress appears to be a general phenomenon not restricted to lipase-expressing cells, which suggests a lipase-independent cellular role for this protein in ER homeostasis.
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Affiliation(s)
- Hui Z Mao
- From the Medical Genetics Research Institute and
| | | | - Candy Bedoya
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California 90048
| | - Javier A Gomez
- Department of Anatomy and Cell Biology and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Diane DeZwaan-McCabe
- Department of Anatomy and Cell Biology and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Imran N Mungrue
- the Department of Pharmacology and Experimental Therapeutics, Louisiana State University School of Medicine, New Orleans, Louisiana 70112
| | - Randal J Kaufman
- Degenerative Disease Research, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, and
| | - D Thomas Rutkowski
- Department of Anatomy and Cell Biology and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Miklós Péterfy
- From the Medical Genetics Research Institute and Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California 90048, the Department of Medicine, David Geffen School of Medicine at the University of California, Los Angeles, California 90095
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Ehrhardt N, Bedoya C, Péterfy M. Embryonic viability, lipase deficiency, hypertriglyceridemia and neonatal lethality in a novel LMF1-deficient mouse model. Nutr Metab (Lond) 2014; 11:37. [PMID: 25302068 PMCID: PMC4190935 DOI: 10.1186/1743-7075-11-37] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 08/12/2014] [Indexed: 11/22/2022] Open
Abstract
Background Lipase Maturation Factor 1 (LMF1) is an ER-chaperone involved in the post-translational maturation and catalytic activation of vascular lipases including lipoprotein lipase (LPL), hepatic lipase (HL) and endothelial lipase (EL). Mutations in LMF1 are associated with lipase deficiency and severe hypertriglyceridemia indicating the critical role of LMF1 in plasma lipid homeostasis. The currently available mouse model of LMF1 deficiency is based on a naturally occurring truncating mutation, combined lipase deficiency (cld), which may represent a hypomorphic allele. Thus, development of LMF1-null mice is needed to explore the phenotypic consequences of complete LMF1 deficiency. Findings In situ hybridization and qPCR analysis in the normal mouse embryo revealed ubiquitous and high-level LMF1 expression. To investigate if LMF1 was required for embryonic viability, a novel mouse model based on a null-allele of LMF1 was generated and characterized. LMF1-/- progeny were born at Mendelian ratios and exhibited combined lipase deficiency, hypertriglyceridemia and neonatal lethality. Conclusion Our results raise the possibility of a previously unrecognized role for LMF1 in embryonic development, but indicate that LMF1 is dispensable for the viability of mouse embryo. The novel mouse model developed in this study will be useful to investigate the full phenotypic spectrum of LMF1 deficiency.
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Affiliation(s)
- Nicole Ehrhardt
- Medical Genetics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Candy Bedoya
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Miklós Péterfy
- Medical Genetics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA ; Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA ; Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Babilonia-Rosa MA, Neher SB. Purification, cellular levels, and functional domains of lipase maturation factor 1. Biochem Biophys Res Commun 2014; 450:423-8. [PMID: 24909692 DOI: 10.1016/j.bbrc.2014.05.136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 05/28/2014] [Indexed: 01/17/2023]
Abstract
Over a third of the US adult population has hypertriglyceridemia, resulting in an increased risk of atherosclerosis, pancreatitis, and metabolic syndrome. Lipoprotein lipase (LPL), a dimeric enzyme, is the main lipase responsible for TG clearance from the blood after food intake. LPL requires an endoplasmic reticulum (ER)-resident, transmembrane protein known as lipase maturation factor 1 (LMF1) for secretion and enzymatic activity. LMF1 is believed to act as a client specific chaperone for dimeric lipases, but the precise mechanism by which LMF1 functions is not understood. Here, we examine which domains of LMF1 contribute to dimeric lipase maturation by assessing the function of truncation variants. N-terminal truncations of LMF1 show that all the domains are necessary for LPL maturation. Fluorescence microscopy and protease protection assays confirmed that these variants were properly oriented in the ER. We measured cellular levels of LMF1 and found that it is expressed at low levels and each molecule of LMF1 promotes the maturation of 50 or more molecules of LPL. Thus we provide evidence for the critical role of the N-terminus of LMF1 for the maturation of LPL and relevant ratio of chaperone to substrate.
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Affiliation(s)
- Melissa A Babilonia-Rosa
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Saskia B Neher
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
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Chokshi N, Blumenschein SD, Ahmad Z, Garg A. Genotype-phenotype relationships in patients with type I hyperlipoproteinemia. J Clin Lipidol 2014; 8:287-95. [PMID: 24793350 DOI: 10.1016/j.jacl.2014.02.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 01/07/2014] [Accepted: 02/12/2014] [Indexed: 12/17/2022]
Abstract
CONTEXT Type I hyperlipoproteinemia (T1HLP) is a rare, autosomal recessive disorder characterized by extreme hypertriglyceridemia that fails to respond to lipid-lowering agents, predisposing to frequent attacks of acute pancreatitis. Mutations in lipoprotein lipase (LPL), apolipoprotein CII (APOC2), lipase maturation factor 1 (LMF1), glycosyl-phosphatidylinositol anchored high-density lipoprotein-binding protein 1 (GPIHBP1), and apolipoprotein AV (APOA5) cause T1HLP, but we lack data on phenotypic variations among the different genetic subtypes. OBJECTIVE To study genotype-phenotype relationships among subtypes of T1HLP patients. DESIGN/INTERVENTION Genetic screening for mutations in LPL, APOC2, GPIHBP1, LMF1, and APOA5. SETTING Tertiary referral center. PATIENTS Ten patients (7 female, 3 male) with chylomicronemia, serum triglyceride levels about 2000 mg/dL, and no secondary causes of hypertriglyceridemia. MAIN OUTCOME MEASURES Genotyping and phenotypic features. RESULTS Four patients harbored homozygous or compound heterozygous mutations in LPL, 3 had homozygous mutations in GPIHBP1, and 1 had a heterozygous APOA5 mutation. We failed to fully identify the genetic etiology in 2 cases: 1 had a heterozygous LPL mutation only and another did not have any mutations. We identified 2 interesting phenotypic features: the patient with heterozygous APOA5 mutation normalized triglyceride levels with weight loss and fish oil therapy, and all 7 female patients were anemic. CONCLUSIONS Our data suggest the possibility of novel loci for T1HLP. We observed that heterozygous APOA5 mutation can cause T1HLP but such patients may unexpectedly respond to therapy, and females with T1HLP suffer from anemia. Further studies of larger cohorts may elucidate more phenotype-genotypes relationships among T1HLP subtypes.
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Affiliation(s)
- Neema Chokshi
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition
| | - Sarah D Blumenschein
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390
| | - Zahid Ahmad
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition
| | - Abhimanyu Garg
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition.
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Molecular analysis of chylomicronemia in a clinical laboratory setting: Diagnosis of 13 cases of lipoprotein lipase deficiency. Clin Chim Acta 2014; 429:61-8. [DOI: 10.1016/j.cca.2013.11.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 11/09/2013] [Accepted: 11/22/2013] [Indexed: 01/05/2023]
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Abstract
All organisms use fatty acids (FAs) for energy substrates and as precursors for membrane and signaling lipids. The most efficient way to transport and store FAs is in the form of triglycerides (TGs); however, TGs are not capable of traversing biological membranes and therefore need to be cleaved by TG hydrolases ("lipases") before moving in or out of cells. This biochemical process is generally called "lipolysis." Intravascular lipolysis degrades lipoprotein-associated TGs to FAs for their subsequent uptake by parenchymal cells, whereas intracellular lipolysis generates FAs and glycerol for their release (in the case of white adipose tissue) or use by cells (in the case of other tissues). Although the importance of lipolysis has been recognized for decades, many of the key proteins involved in lipolysis have been uncovered only recently. Important new developments include the discovery of glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), the molecule that moves lipoprotein lipase from the interstitial spaces to the capillary lumen, and the discovery of adipose triglyceride lipase (ATGL) and comparative gene identification-58 (CGI-58) as crucial molecules in the hydrolysis of TGs within cells. This review summarizes current views of lipolysis and highlights the relevance of this process to human disease.
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Affiliation(s)
- Stephen G. Young
- Department of Medicine
- Department of Human Genetics, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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Dussaillant C, Serrano V, Maiz A, Eyheramendy S, Cataldo LR, Chavez M, Smalley SV, Fuentes M, Rigotti A, Rubio L, Lagos CF, Martinez JA, Santos JL. APOA5 Q97X mutation identified through homozygosity mapping causes severe hypertriglyceridemia in a Chilean consanguineous family. BMC MEDICAL GENETICS 2012; 13:106. [PMID: 23151256 PMCID: PMC3523038 DOI: 10.1186/1471-2350-13-106] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 10/23/2012] [Indexed: 12/31/2022]
Abstract
Background Severe hypertriglyceridemia (HTG) has been linked to defects in LPL, APOC2, APOA5, LMF1 and GBIHBP1 genes. However, a number of severe HTG cases are probably caused by as yet unidentified mutations. Very high triglyceride plasma levels (>112 mmol/L at diagnosis) were found in two sisters of a Chilean consanguineous family, which is strongly suggestive of a recessive highly penetrant mutation. The aim of this study was to determine the genetic locus responsible for the severe HTG in this family. Methods We carried out a genome-wide linkage study with nearly 300,000 biallelic markers (Illumina Human CytoSNP-12 panel). Using the homozygosity mapping strategy, we searched for chromosome regions with excess of homozygous genotypes in the affected cases compared to non-affected relatives. Results A large homozygous segment was found in the long arm of chromosome 11, with more than 2,500 consecutive homozygous SNP shared by the proband with her affected sister, and containing the APOA5/A4/C3/A1 cluster. Direct sequencing of the APOA5 gene revealed a known homozygous nonsense Q97X mutation (p.Gln97Ter) found in both affected sisters but not in non-affected relatives nor in a sample of unrelated controls. Conclusion The Q97X mutation of the APOA5 gene in homozygous status is responsible for the severe hypertriglyceridemia in this family. We have shown that homozygosity mapping correctly pinpointed the genomic region containing the gene responsible for severe hypertriglyceridemia in this consanguineous Chilean family.
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Affiliation(s)
- Catalina Dussaillant
- Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, Alameda, Santiago, Chile
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Abstract
Demonstration of a direct relationship between plasma triglyceride (TG) concentration and atherosclerosis has proven difficult due to confounding variables that accompany elevated plasma TG, such as other dyslipidemias, obesity, and type 2 diabetes. However, human genetic studies have provided evidence suggesting a causal link between plasma TG and cardiovascular risk. Analyses in human patients with hypertriglyceridemia (HTG) also provides insight into the relationship between genetic variation, predisposition to elevated plasma TG, and risk of subsequent cardiovascular disease. Here, we review recent key studies that have contributed to our understanding of the genetic determinants of plasma TG concentration, including HTG susceptibility and phenotypic heterogeneity, and discuss our maturing model of the allelic and phenotypic spectrum of plasma TG.
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Chen YH, Chen K, Yang YS, Xie WR, Du ZW, Wang H. Advances in understanding the role of gene mutations in the pathogenesis of hyperlipidemic acute pancreatitis. Shijie Huaren Xiaohua Zazhi 2012; 20:2364-2369. [DOI: 10.11569/wcjd.v20.i25.2364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute pancreatitis (AP) is a common disorder that manifests as acute abdomen and has an extremely high mortality rate. At present, the pathogenesis of AP has become a hot topic of research but has not been completely clarified yet. The relationship between hyperlipidemia (HL) and AP has attracted wide attention. Gene mutations, especially mutations in the lipoprotein lipase (LPL), glycosylphosphatidylinositol anchored high density lipoprotein-binding protein 1 (GPIHBP1) and apolipoprotein A-V (apoA-V) genes, are closely associated with the pathogenesis of HL and recurrent pancreatitis. In this article, we will review the recent progress in understanding the role of gene mutations in the pathogenesis of hyperlipidemic AP (HLAP).
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Surendran RP, Visser ME, Heemelaar S, Wang J, Peter J, Defesche JC, Kuivenhoven JA, Hosseini M, Péterfy M, Kastelein JJP, Johansen CT, Hegele RA, Stroes ESG, Dallinga-Thie GM. Mutations in LPL, APOC2, APOA5, GPIHBP1 and LMF1 in patients with severe hypertriglyceridaemia. J Intern Med 2012; 272:185-96. [PMID: 22239554 PMCID: PMC3940136 DOI: 10.1111/j.1365-2796.2012.02516.x] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVES The severe forms of hypertriglyceridaemia (HTG) are caused by mutations in genes that lead to the loss of function of lipoprotein lipase (LPL). In most patients with severe HTG (TG > 10 mmol L(-1) ), it is a challenge to define the underlying cause. We investigated the molecular basis of severe HTG in patients referred to the Lipid Clinic at the Academic Medical Center Amsterdam. METHODS The coding regions of LPL, APOC2, APOA5 and two novel genes, lipase maturation factor 1 (LMF1) and GPI-anchored high-density lipoprotein (HDL)-binding protein 1 (GPIHBP1), were sequenced in 86 patients with type 1 and type 5 HTG and 327 controls. RESULTS In 46 patients (54%), rare DNA sequence variants were identified, comprising variants in LPL (n = 19), APOC2 (n = 1), APOA5 (n = 2), GPIHBP1 (n = 3) and LMF1 (n = 8). In 22 patients (26%), only common variants in LPL (p.Asp36Asn, p.Asn318Ser and p.Ser474Ter) and APOA5 (p.Ser19Trp) could be identified, whereas no mutations were found in 18 patients (21%). In vitro validation revealed that the mutations in LMF1 were not associated with compromised LPL function. Consistent with this, five of the eight LMF1 variants were also found in controls and therefore cannot account for the observed phenotype. CONCLUSIONS The prevalence of mutations in LPL was 34% and mostly restricted to patients with type 1 HTG. Mutations in GPIHBP1 (n = 3), APOC2 (n = 1) and APOA5 (n = 2) were rare but the associated clinical phenotype was severe. Routine sequencing of candidate genes in severe HTG has improved our understanding of the molecular basis of this phenotype associated with acute pancreatitis and may help to guide future individualized therapeutic strategies.
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Affiliation(s)
- R P Surendran
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
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Hosseini M, Ehrhardt N, Weissglas-Volkov D, Lai CM, Mao HZ, Liao JL, Nikkola E, Bensadoun A, Taskinen MR, Doolittle MH, Pajukanta P, Péterfy M. Transgenic expression and genetic variation of Lmf1 affect LPL activity in mice and humans. Arterioscler Thromb Vasc Biol 2012; 32:1204-10. [PMID: 22345169 DOI: 10.1161/atvbaha.112.245696] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Lipoprotein lipase (LPL) is a principal enzyme in lipoprotein metabolism, tissue lipid utilization, and energy metabolism. LPL is synthesized by parenchymal cells in adipose, heart, and muscle tissues followed by secretion to extracellular sites, where lipolyic function is exerted. The catalytic activity of LPL is attained during posttranslational maturation, which involves glycosylation, folding, and subunit assembly within the endoplasmic reticulum. A lipase-chaperone, lipase maturation factor 1 (Lmf1), has recently emerged as a critical factor in this process. Previous studies demonstrated that loss-of-function mutations of Lmf1 result in diminished lipase activity and severe hypertriglyceridemia in mice and human subjects. The objective of this study is to investigate whether, beyond its role as a required factor in lipase maturation, variation in Lmf1 expression is sufficient to modulate LPL activity in vivo. METHODS AND RESULTS To assess the effects of Lmf1 overexpression in adipose and muscle tissues, we generated aP2-Lmf1 and Mck-Lmf1 transgenic mice. Characterization of relevant tissues revealed increased LPL activity in both mouse strains. In the omental and subcutaneous adipose depots, Lmf1 overexpression was associated with increased LPL specific activity without changes in LPL mass. In contrast, increased LPL activity was due to elevated LPL protein level in heart and gonadal adipose tissue. To extend these studies to humans, we detected association between LMF1 gene variants and postheparin LPL activity in a dyslipidemic cohort. CONCLUSIONS Our results suggest that variation in Lmf1 expression is a posttranslational determinant of LPL activity.
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Affiliation(s)
- Maryam Hosseini
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
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Pisciotta L, Fresa R, Bellocchio A, Guido V, Oliva CP, Calandra S, Bertolini S. Two novel rare variants of APOA5 gene found in subjects with severe hypertriglyceridemia. Clin Chim Acta 2011; 412:2194-8. [DOI: 10.1016/j.cca.2011.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 08/02/2011] [Accepted: 08/02/2011] [Indexed: 10/17/2022]
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Johansen CT, Hegele RA. Allelic and phenotypic spectrum of plasma triglycerides. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:833-42. [PMID: 22033228 DOI: 10.1016/j.bbalip.2011.10.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 10/04/2011] [Indexed: 01/10/2023]
Abstract
The genetic underpinnings of both normal and pathological variation in plasma triglyceride (TG) concentration are relatively well understood compared to many other complex metabolic traits. For instance, genome-wide association studies (GWAS) have revealed 32 common variants that are associated with plasma TG concentrations in healthy epidemiologic populations. Furthermore, GWAS in clinically ascertained hypertriglyceridemia (HTG) patients have shown that almost all of the same TG-raising alleles from epidemiologic samples are also associated with HTG disease status, and that greater accumulation of these alleles reflects the severity of the HTG phenotype. Finally, comprehensive resequencing studies show a burden of rare variants in some of these same genes - namely in LPL, GCKR, APOB and APOA5 - in HTG patients compared to normolipidemic controls. A more complete understanding of the genes and genetic variants associated with plasma TG concentration will enrich our understanding of the molecular pathways that modulate plasma TG metabolism, which may translate into clinical benefit. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
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Péterfy M. Lipase maturation factor 1: a lipase chaperone involved in lipid metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:790-4. [PMID: 22063272 DOI: 10.1016/j.bbalip.2011.10.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 10/03/2011] [Accepted: 10/04/2011] [Indexed: 10/16/2022]
Abstract
Mutations in lipase maturation factor 1 (LMF1) are associated with severe hypertriglyceridemia in mice and human subjects. The underlying cause is impaired lipid clearance due to lipase deficiency. LMF1 is a chaperone of the endoplasmic reticulum (ER) and it is critically required for the post-translational activation of three vascular lipases: lipoprotein lipase (LPL), hepatic lipase (HL) and endothelial lipase (EL). As LMF1 is only required for the maturation of homodimeric, but not monomeric, lipases, it is likely involved in the assembly of inactive lipase subunits into active enzymes and/or the stabilization of active dimers. Herein, we provide an overview of current understanding of LMF1 function and propose that it may play a regulatory role in lipase activation and lipid metabolism. Further studies will be required to test this hypothesis and elucidate the full spectrum of phenotypes in combined lipase deficiency. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
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Affiliation(s)
- Miklós Péterfy
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States.
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van de Woestijne AP, Monajemi H, Kalkhoven E, Visseren FLJ. Adipose tissue dysfunction and hypertriglyceridemia: mechanisms and management. Obes Rev 2011; 12:829-40. [PMID: 21749607 DOI: 10.1111/j.1467-789x.2011.00900.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Elevated plasma triglyceride levels, as often seen in obese subjects, are independently associated with an increased risk of cardiovascular diseases. By secreting adipokines (such as adiponectin and leptin) and other proteins (such as lipoprotein lipase and cholesteryl ester transferase protein), adipose tissue affects triglyceride metabolism. In obesity, adipocyte hypertrophy leads to many changes in adipocyte function and production of anti- and pro-inflammatory cytokines. Furthermore, free fatty acids are released into the circulation contributing to insulin resistance. Adipose tissue dysfunction will eventually lead to abnormalities in lipid metabolism, such as hypertriglyceridemia (due to increased hepatic very-low-density lipoprotein production and decreased triglyceride hydrolysis), small dense low-density lipoprotein particles, remnant lipoproteins and low high-density lipoprotein cholesterol levels, all associated with a higher risk for the development of cardiovascular diseases. The clinical implications of elevated plasma triglycerides are still a matter of debate. Understanding the pathophysiology of adipose tissue dysfunction in obesity, which is becoming a pandemic condition, is essential for designing appropriate therapeutic interventions. Lifestyle changes are important to improve adipose tissue function in obese patients. Pharmacological interventions to improve adipose tissue function need further evaluation. Although statins are not very potent in reducing plasma triglycerides, they remain the mainstay of therapy for cardiovascular risk reduction in high-risk patients.
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Affiliation(s)
- A P van de Woestijne
- Department of Vascular Medicine, University Medical Center, Utrecht, the Netherlands Department of Metabolic and Endocrine Diseases, University Medical Center, Utrecht, the Netherlands
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Abstract
PURPOSE OF REVIEW Hypertriglyceridemia (HTG) is a common diagnosis. Although secondary factors are important for clinical expression, susceptibility to HTG has a strong genetic component, which we review here. RECENT FINDINGS Severe HTG in a few families follows Mendelian - typically autosomal recessive - inheritance of rare loss-of-function mutations in genes such as LPL, APOC2, APOA5, LMF1, and GPIHBP1. In contrast, common complex HTG results from the cumulative influence of small-effect variants (single nucleotide polymorphisms) in genes such as APOA5, GCKR, LPL, and APOB. Intensive resequencing of these four genes has also shown accumulated heterozygous rare variants in HTG patients. Together, more than 20% of the susceptibility to HTG is now accounted for by common and rare variants. Further, classical Fredrickson HTG phenotypes, which were once considered to be distinct based on biochemical features, have a shared genetic architecture. SUMMARY Compared to other complex traits, genetic variants account for a high proportion of HTG diagnoses. By tallying the number of HTG risk alleles, it is possible to discriminate between individuals with HTG and normolipidemia, particularly in those with extreme scores. Future directions include finding the missing genetic component and determining whether genetic profiling can help with diagnosis or personalized treatment advice.
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Affiliation(s)
- Christopher T Johansen
- Departments of Biochemistry and Medicine, Robarts Research Institute and Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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Ben-Zeev O, Hosseini M, Lai CM, Ehrhardt N, Wong H, Cefalù AB, Noto D, Averna MR, Doolittle MH, Péterfy M. Lipase maturation factor 1 is required for endothelial lipase activity. J Lipid Res 2011; 52:1162-1169. [PMID: 21447484 DOI: 10.1194/jlr.m011155] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Lipase maturation factor 1 (Lmf1) is an endoplasmic reticulum (ER) membrane protein involved in the posttranslational folding and/or assembly of lipoprotein lipase (LPL) and hepatic lipase (HL) into active enzymes. Mutations in Lmf1 are associated with diminished LPL and HL activities ("combined lipase deficiency") and result in severe hypertriglyceridemia in mice as well as in human subjects. Here, we investigate whether endothelial lipase (EL) also requires Lmf1 to attain enzymatic activity. We demonstrate that cells harboring a (cld) loss-of-function mutation in the Lmf1 gene are unable to generate active EL, but they regain this capacity after reconstitution with the Lmf1 wild type. Furthermore, we show that cellular EL copurifies with Lmf1, indicating their physical interaction in the ER. Finally, we determined that post-heparin phospholipase activity in a patient with the LMF1(W464X) mutation is reduced by more than 95% compared with that in controls. Thus, our study indicates that EL is critically dependent on Lmf1 for its maturation in the ER and demonstrates that Lmf1 is a required factor for all three vascular lipases, LPL, HL, and EL.
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Affiliation(s)
- Osnat Ben-Zeev
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Maryam Hosseini
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA; Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Ching-Mei Lai
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Nicole Ehrhardt
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Howard Wong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Angelo B Cefalù
- Department of Clinical Medicine and Emerging Diseases, University of Palermo, Palermo, Italy
| | - Davide Noto
- Department of Clinical Medicine and Emerging Diseases, University of Palermo, Palermo, Italy
| | - Maurizio R Averna
- Department of Clinical Medicine and Emerging Diseases, University of Palermo, Palermo, Italy
| | - Mark H Doolittle
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Miklós Péterfy
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA; Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA.
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Características clínicas de los pacientes con hipertrigliceridemia remitidos a las Unidades de Lípidos: registro de hipertrigliceridemias de la Sociedad Española de Arteriosclerosis. Med Clin (Barc) 2011; 136:231-8. [DOI: 10.1016/j.medcli.2010.09.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 08/03/2010] [Accepted: 09/07/2010] [Indexed: 10/18/2022]
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Johansen CT, Kathiresan S, Hegele RA. Genetic determinants of plasma triglycerides. J Lipid Res 2010; 52:189-206. [PMID: 21041806 DOI: 10.1194/jlr.r009720] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Plasma triglyceride (TG) concentration is reemerging as an important cardiovascular disease risk factor. More complete understanding of the genes and variants that modulate plasma TG should enable development of markers for risk prediction, diagnosis, prognosis, and response to therapies and might help specify new directions for therapeutic interventions. Recent genome-wide association studies (GWAS) have identified both known and novel loci associated with plasma TG concentration. However, genetic variation at these loci explains only ∼10% of overall TG variation within the population. As the GWAS approach may be reaching its limit for discovering genetic determinants of TG, alternative genetic strategies, such as rare variant sequencing studies and evaluation of animal models, may provide complementary information to flesh out knowledge of clinically and biologically important pathways in TG metabolism. Herein, we review genes recently implicated in TG metabolism and describe how some of these genes likely modulate plasma TG concentration. We also discuss lessons regarding plasma TG metabolism learned from various genomic and genetic experimental approaches. Treatment of patients with moderate to severe hypertriglyceridemia with existing therapies is often challenging; thus, gene products and pathways found in recent genetic research studies provide hope for development of more effective clinical strategies.
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Affiliation(s)
- Christopher T Johansen
- Department of Biochemistry, Robarts Research Institute, University of Western Ontario, London, Ontario N6A 5K8, Canada
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Abstract
PURPOSE OF REVIEW Lipase maturation factor 1 (LMF1) is a membrane-bound protein located in the endoplasmic reticulum. It is essential to the folding and assembly (i.e., maturation) of a selected group of lipases that include lipoprotein lipase, hepatic lipase and endothelial lipase. The purpose of this review is to examine recent studies that have begun to elucidate the structure and function of LMF1 and to place it in the context of lipase folding and assembly. RECENT FINDINGS Recent studies identified mutations in LMF1 that cause combined lipase deficiency and hypertriglyceridemia in humans. These mutations result in the truncation of a large, evolutionarily conserved domain (DUF1222), which is essential for interaction with lipases and their attainment of enzymatic activity. The structural complexity of LMF1 has been further characterized by solving its topology in the endoplasmic reticulum membrane. Recent studies indicate that in addition to lipoprotein lipase and hepatic lipase, the maturation of endothelial lipase is also dependent on LMF1. Based on its apparent specificity for dimeric lipases, LMF1 is proposed to play an essential role in the assembly and/or stabilization of head-to-tail lipase homodimers. SUMMARY LMF1 functions in the maturation of a selected group of secreted lipases that assemble into homodimers in the endoplasmic reticulum. These dimeric lipases include lipoprotein lipase, hepatic lipase and endothelial lipase, all of which contribute significantly to plasma triglyceride and high-density lipoprotein cholesterol levels in humans. Future studies involving genetically engineered mouse models will be required to fully elucidate the role of LMF1 in normal physiology and diseases.
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Affiliation(s)
- Mark H. Doolittle
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, and VA Greater Los Angeles Healthcare System, 11301 Wilshire Blvd., Bldg. 113, Rm. 312, Los Angeles, CA 90073, USA, Tel.: 661-433-6349, Fax: 310-268-4981,
| | - Nicole Ehrhardt
- Medical Genetics Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA, Tel.: 310-423-3862, Fax: 310-423-0299,
| | - Miklós Péterfy
- Medical Genetics Institute, Cedars-Sinai Medical Center, and Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, 8700 Beverly Blvd., Los Angeles, CA 90048, USA, Tel.: 310-478-3711 x42153, Fax: 310-268-4981,
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Dallinga-Thie GM, Franssen R, Mooij HL, Visser ME, Hassing HC, Peelman F, Kastelein JJP, Péterfy M, Nieuwdorp M. The metabolism of triglyceride-rich lipoproteins revisited: new players, new insight. Atherosclerosis 2009; 211:1-8. [PMID: 20117784 DOI: 10.1016/j.atherosclerosis.2009.12.027] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 12/17/2009] [Accepted: 12/18/2009] [Indexed: 12/31/2022]
Abstract
Peripheral lipoprotein lipase (LPL)-mediated lipolysis of triglycerides is the first step in chylomicron/VLDL clearance involving heparan sulfate proteoglycans (HSPGs) displayed at the cell surface of the capillaries in adipose tissue, heart and skeletal muscle. The newly generated chylomicron remnant particles are then cleared by the liver, whereas VLDL remnant particles are either further modified, through the action of hepatic lipase (HL) and cholesteryl ester transfer protein (CETP), into LDL particles or alternatively directly cleared by the liver. Two proteins, lipase maturation factor 1 (LMF1) and glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1), have been recently identified and have revised our current understanding of LPL maturation and LPL-mediated lipolysis. Moreover, new insights have been gained with respect to hepatic remnant clearance using genetically modified mice targeting the sulfation of HSPGs and even deletion of the most abundant heparan sulfate proteoglycan: syndecan1. In this review, we will provide an overview of novel data on both peripheral TG hydrolysis and hepatic remnant clearance that will improve our knowledge of plasma triglyceride metabolism.
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Affiliation(s)
- Geesje M Dallinga-Thie
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands.
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Abstract
Lipases are acyl hydrolases that represent a diverse group of enzymes present in organisms ranging from prokaryotes to humans. This article focuses on an evolutionarily related family of extracellular lipases that include lipoprotein lipase, hepatic lipase and endothelial lipase. As newly synthesized proteins, these lipases undergo a series of co- and post-translational maturation steps occurring in the endoplasmic reticulum, including glycosylation and glycan processing, and protein folding and subunit assembly. This article identifies and discusses mechanisms that direct early and late events in lipase folding and assembly. Lipase maturation employs the two general chaperone systems operating in the endoplasmic reticulum, as well as a recently identified lipase-specific chaperone termed lipase maturation factor 1. We propose that the two general chaperone systems act in a coordinated manner early in lipase maturation in order to help create partially folded monomers; lipase maturation factor 1 then facilitates final monomer folding and subunit assembly into fully functional homodimers. Once maturation is complete, the lipases exit the endoplasmic reticulum and are secreted to extracellular sites, where they carry out a number of functions related to lipoprotein and lipid metabolism.
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Affiliation(s)
- Mark H Doolittle
- VA Greater Los Angeles, Healthcare System, 11301 Wilshire Blvd, Bldg 113, Rm 312, Los Angeles, CA 90073, USA, Tel.: +1 661 433 6349
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