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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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Kurooka N, Eguchi J, Wada J. Role of glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 in hypertriglyceridemia and diabetes. J Diabetes Investig 2023; 14:1148-1156. [PMID: 37448184 PMCID: PMC10512915 DOI: 10.1111/jdi.14056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 06/25/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
In diabetes, the impairment of insulin secretion and insulin resistance contribute to hypertriglyceridemia, as the enzymatic activity of lipoprotein lipase (LPL) depends on insulin action. The transport of LPL to endothelial cells and its enzymatic activity are maintained by the formation of lipolytic complex depending on the multiple positive (glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 [GPIHBP1], apolipoprotein C-II [APOC2], APOA5, heparan sulfate proteoglycan [HSPG], lipase maturation factor 1 [LFM1] and sel-1 suppressor of lin-12-like [SEL1L]) and negative regulators (APOC1, APOC3, angiopoietin-like proteins [ANGPTL]3, ANGPTL4 and ANGPTL8). Among the regulators, GPIHBP1 is a crucial molecule for the translocation of LPL from parenchymal cells to the luminal surface of capillary endothelial cells, and maintenance of lipolytic activity; that is, hydrolyzation of triglyceride into free fatty acids and monoglyceride, and conversion from chylomicron to chylomicron remnant in the exogenous pathway and from very low-density lipoprotein to low-density lipoprotein in the endogenous pathway. The null mutation of GPIHBP1 causes severe hypertriglyceridemia and pancreatitis, and GPIGBP1 autoantibody syndrome also causes severe hypertriglyceridemia and recurrent episodes of acute pancreatitis. In patients with type 2 diabetes, the elevated serum triglyceride levels negatively correlate with circulating LPL levels, and positively with circulating APOC1, APOC3, ANGPTL3, ANGPTL4 and ANGPTL8 levels. In contrast, circulating GPIHBP1 levels are not altered in type 2 diabetes patients with higher serum triglyceride levels, whereas they are elevated in type 2 diabetes patients with diabetic retinopathy and nephropathy. The circulating regulators of lipolytic complex might be new biomarkers for lipid and glucose metabolism, and diabetic vascular complications.
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Affiliation(s)
- Naoko Kurooka
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Faculty of Medicine, Dentistry and Pharmaceutical SciencesOkayama UniversityOkayamaJapan
| | - Jun Eguchi
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Faculty of Medicine, Dentistry and Pharmaceutical SciencesOkayama UniversityOkayamaJapan
| | - Jun Wada
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Faculty of Medicine, Dentistry and Pharmaceutical SciencesOkayama UniversityOkayamaJapan
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Sustar U, Groselj U, Khan SA, Shafi S, Khan I, Kovac J, Bizjan BJ, Battelino T, Sadiq F. A homozygous variant in the GPIHBP1 gene in a child with severe hypertriglyceridemia and a systematic literature review. Front Genet 2022; 13:983283. [PMID: 36051701 PMCID: PMC9424485 DOI: 10.3389/fgene.2022.983283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Due to nonspecific symptoms, rare dyslipidaemias are frequently misdiagnosed, overlooked, and undertreated, leading to increased risk for severe cardiovascular disease, pancreatitis and/or multiple organ failures before diagnosis. Better guidelines for the recognition and early diagnosis of rare dyslipidaemias are urgently required. Methods: Genomic DNA was isolated from blood samples of a Pakistani paediatric patient with hypertriglyceridemia, and from his parents and siblings. Next-generation sequencing (NGS) was performed, and an expanded dyslipidaemia panel was employed for genetic analysis. Results: The NGS revealed the presence of a homozygous missense pathogenic variant c.230G>A (NM_178172.6) in exon 3 of the GPIHBP1 (glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1) gene resulting in amino acid change p.Cys77Tyr (NP_835466.2). The patient was 5.5 years old at the time of genetic diagnosis. The maximal total cholesterol and triglyceride levels were measured at the age of 10 months (850.7 mg/dl, 22.0 mmol/L and 5,137 mg/dl, 58.0 mmol/L, respectively). The patient had cholesterol deposits at the hard palate, eruptive xanthomas, lethargy, poor appetite, and mild splenomegaly. Both parents and sister were heterozygous for the familial variant in the GPIHBP1 gene. Moreover, in the systematic review, we present 62 patients with pathogenic variants in the GPIHBP1 gene and clinical findings, associated with hyperlipoproteinemia. Conclusion: In a child with severe hypertriglyceridemia, we identified a pathogenic variant in the GPIHBP1 gene causing hyperlipoproteinemia (type 1D). In cases of severe elevations of plasma cholesterol and/or triglycerides genetic testing for rare dyslipidaemias should be performed as soon as possible for optimal therapy and patient management.
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Affiliation(s)
- Ursa Sustar
- Department of Endocrinology, Diabetes and Metabolism, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Urh Groselj
- Department of Endocrinology, Diabetes and Metabolism, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
- *Correspondence: Urh Groselj, ; Fouzia Sadiq,
| | - Sabeen Abid Khan
- Department of Paediatrics, Shifa College of Medicine, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Saeed Shafi
- Department of Anatomy, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Iqbal Khan
- Department of Vascular Surgery, Shifa International Hospital, Islamabad, Pakistan
- Department of Vascular Surgery, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Jernej Kovac
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Barbara Jenko Bizjan
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Tadej Battelino
- Department of Endocrinology, Diabetes and Metabolism, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Fouzia Sadiq
- Directorate of Research, Shifa Tameer-e-Millat University, Islamabad, Pakistan
- *Correspondence: Urh Groselj, ; Fouzia Sadiq,
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Zhang G, Yang Q, Mao W, Hu Y, Pu N, Deng H, Yu X, Zhang J, Zhou J, Ye B, Li G, Li B, Ke L, Tong Z, Murakami M, Kimura T, Nakajima K, Cao W, Liu Y, Li W. GPIHBP1 autoantibody is an independent risk factor for the recurrence of hypertriglyceridemia-induced acute pancreatitis. J Clin Lipidol 2022; 16:626-634. [DOI: 10.1016/j.jacl.2022.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 10/15/2022]
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Liu S, Wang Z, Zheng X, Zhang Y, Wei S, OuYang H, Liang J, Chen N, Zeng W, Jiang J. Case Report: Successful Management of a 29-Day-Old Infant With Severe Hyperlipidemia From a Novel Homozygous Variant of GPIHBP1 Gene. Front Pediatr 2022; 10:792574. [PMID: 35359903 PMCID: PMC8960264 DOI: 10.3389/fped.2022.792574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 02/03/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Severe hyperlipidemia is characterized by markedly elevated blood triglyceride levels and severe early-onset cardiovascular diseases, pancreatitis, pancreatic necrosis or persistent multiple organ failure if left untreated. It is a rare autosomal recessive metabolic disorder originated from the variants of lipoprotein lipase gene, and previous studies have demonstrated that most cases with severe hyperlipidemia are closely related to the variants of some key genes for lipolysis, such as LPL, APOC2, APOA5, LMF1, and GPIHBP1. Meanwhile, other unidentified causes also exist and are equally worthy of attention. METHODS The 29-day-old infant was diagnosed with severe hyperlipidemia, registering a plasma triglyceride level as high as 25.46 mmol/L. Whole exome sequencing was conducted to explore the possible pathogenic gene variants for this patient. RESULTS The infant was put on a low-fat diet combined with pharmacological therapy, which was successful in restraining the level of serum triglyceride and total cholesterol to a low to medium range during the follow-ups. The patient was found to be a rare novel homozygous duplication variant-c.45_48dupGCGG (Pro17Alafs*22) in GPIHBP1 gene-leading to a frameshift which failed to form the canonical termination codon TGA. The mutant messenger RNA should presumably produce a peptide consisting of 16 amino acids at the N-terminus, with 21 novel amino acids on the heels of the wild-type protein. CONCLUSIONS Our study expands on the spectrum of GPIHBP1 variants and contributes to a more comprehensive understanding of the genetic diagnosis, genetic counseling, and multimodality therapy of families with severe hyperlipidemia. Our experience gained in this study is also contributory to a deeper insight into severe hyperlipidemia and highlights the importance of molecular genetic tests.
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Affiliation(s)
- Shu Liu
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Zhiqing Wang
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xianhua Zheng
- Department of Clinical Laboratory, Guangdong Women and Children Hospital, Guangzhou, China
| | - Ye Zhang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Sisi Wei
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Haimei OuYang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Jinqun Liang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Nuan Chen
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Weihong Zeng
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Jianhui Jiang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
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Circulating GPIHBP1 levels and microvascular complications in patients with type 2 diabetes: A cross-sectional study. J Clin Lipidol 2022; 16:237-245. [DOI: 10.1016/j.jacl.2022.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/27/2021] [Accepted: 01/12/2022] [Indexed: 11/18/2022]
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The intrinsic instability of the hydrolase domain of lipoprotein lipase facilitates its inactivation by ANGPTL4-catalyzed unfolding. Proc Natl Acad Sci U S A 2021; 118:2026650118. [PMID: 33723082 DOI: 10.1073/pnas.2026650118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The complex between lipoprotein lipase (LPL) and its endothelial receptor (GPIHBP1) is responsible for the lipolytic processing of triglyceride-rich lipoproteins (TRLs) along the capillary lumen, a physiologic process that releases lipid nutrients for vital organs such as heart and skeletal muscle. LPL activity is regulated in a tissue-specific manner by endogenous inhibitors (angiopoietin-like [ANGPTL] proteins 3, 4, and 8), but the molecular mechanisms are incompletely understood. ANGPTL4 catalyzes the inactivation of LPL monomers by triggering the irreversible unfolding of LPL's α/β-hydrolase domain. Here, we show that this unfolding is initiated by the binding of ANGPTL4 to sequences near LPL's catalytic site, including β2, β3-α3, and the lid. Using pulse-labeling hydrogen‒deuterium exchange mass spectrometry, we found that ANGPTL4 binding initiates conformational changes that are nucleated on β3-α3 and progress to β5 and β4-α4, ultimately leading to the irreversible unfolding of regions that form LPL's catalytic pocket. LPL unfolding is context dependent and varies with the thermal stability of LPL's α/β-hydrolase domain (T m of 34.8 °C). GPIHBP1 binding dramatically increases LPL stability (T m of 57.6 °C), while ANGPTL4 lowers the onset of LPL unfolding by ∼20 °C, both for LPL and LPL•GPIHBP1 complexes. These observations explain why the binding of GPIHBP1 to LPL retards the kinetics of ANGPTL4-mediated LPL inactivation at 37 °C but does not fully suppress inactivation. The allosteric mechanism by which ANGPTL4 catalyzes the irreversible unfolding and inactivation of LPL is an unprecedented pathway for regulating intravascular lipid metabolism.
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A novel GPIHBP1 mutation related to familial chylomicronemia syndrome: A series of cases. Atherosclerosis 2021; 322:31-38. [PMID: 33706081 DOI: 10.1016/j.atherosclerosis.2021.02.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 02/10/2021] [Accepted: 02/18/2021] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND AIMS GPIHBP1 is an accessory protein of lipoprotein lipase (LPL) essential for its functioning. Mutations in the GPIHBP1 gene cause a deficit in the action of LPL, leading to severe hypertriglyceridemia and increased risk for acute pancreatitis. METHODS We describe twelve patients (nine women) with a novel homozygous mutation in intron 2 of the GPIHBP1 gene. RESULTS All patients were from the Northeastern region of Brazil and presented the same homozygous variant located in a highly conserved 3' splicing acceptor site of the GPIHBP1 gene. This new variant was named c.182-1G > T, according to HGVS recommendations. We verified this new GPIHBP1 variant's effect by using the Human Splicing Finder (HSF) tool. This mutation changes the GPIHBP1 pre-mRNA processing and possibly causes the skipping of the exon 3 of the GPIHBP1 gene, affecting almost 50% of the cysteine-rich Lys6 GPIHBP1 domain. Patients presented with severe hypertriglyceridemia (2351 mg/dl [885-20600]) and low HDL (18 mg/dl [5-41). Four patients (33%) had a previous history of acute pancreatitis. CONCLUSIONS We describe a novel GPIHBP1 pathogenic intronic mutation of patients from the Northeast region of Brazil, suggesting the occurrence of a founder effect.
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Cefalù AB, Giammanco A, Noto D, Spina R, Cabibi D, Barbagallo CM, Averna M. Effectiveness and safety of lomitapide in a patient with familial chylomicronemia syndrome. Endocrine 2021; 71:344-350. [PMID: 33006726 DOI: 10.1007/s12020-020-02506-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/23/2020] [Indexed: 01/14/2023]
Abstract
BACKGROUND Familial chylomicronemia syndrome (FCS) is characterized by severe fasting hypertriglyceridemia, abdominal pain, and recurrent acute pancreatitis. Available triglyceride-lowering drugs are insufficient to avoid pancreatitis. Therefore, there is a significant unmet medical need for effective triglyceride-lowering drugs for patients with FCS. CASE REPORT We report the second case of a patient with FCS and recurrent pancreatitis treated with lomitapide. Lomitapide treatment resulted in a reduction of fasting TG levels from 2897 mg/dL (32.71 mmol/L) to an average of 954 mg/dL (10.77 mmol/L) on the 30 mg lomitapide equating to a 67% reduction from baseline. After 26 months of lomitapide treatment, histological activity score for hepatic fibrosis was stable although liver biopsy showed a marked increase of liver steatosis and mild perivenular and perisinusoidal fibrosis. CONCLUSIONS Lomitapide is effective in reducing triglycerides in FCS and preventing the recurrence of acute pancreatitis. A longer follow-up is necessary to evaluate long-term risk of progression toward severe stages of liver fibrosis. A prospective clinical trial may identify which subgroup of FCS patients would benefit from lomitapide treatment in the absence of significant liver adverse effects.
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Affiliation(s)
- Angelo B Cefalù
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy.
| | - Antonina Giammanco
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy
| | - Davide Noto
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy
| | - Rossella Spina
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy
| | - Daniela Cabibi
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy
| | - Carlo M Barbagallo
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy
| | - Maurizio Averna
- Dipartimento di Promozione della Salute, Materno Infantile, Medicina Interna e Specialistica Di Eccellenza "G. D'Alessandro" (PROMISE), Università degli Studi di Palermo, Via del Vespro 129, 90127, Palermo, Italy.
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Wu SA, Kersten S, Qi L. Lipoprotein Lipase and Its Regulators: An Unfolding Story. Trends Endocrinol Metab 2021; 32:48-61. [PMID: 33277156 PMCID: PMC8627828 DOI: 10.1016/j.tem.2020.11.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 02/07/2023]
Abstract
Lipoprotein lipase (LPL) is one of the most important factors in systemic lipid partitioning and metabolism. It mediates intravascular hydrolysis of triglycerides packed in lipoproteins such as chylomicrons and very-low-density lipoprotein (VLDL). Since its initial discovery in the 1940s, its biology and pathophysiological significance have been well characterized. Nonetheless, several studies in the past decade, with recent delineation of LPL crystal structure and the discovery of several new regulators such as angiopoietin-like proteins (ANGPTLs), glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), lipase maturation factor 1 (LMF1) and Sel-1 suppressor of Lin-12-like 1 (SEL1L), have completely transformed our understanding of LPL biology.
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Affiliation(s)
- Shuangcheng Alivia Wu
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI48105, USA.
| | - Sander Kersten
- Nutrition Metabolism and Genomics group, Wageningen University, Wageningen, The Netherlands
| | - Ling Qi
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI48105, USA; Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA.
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Miyashita K, Lutz J, Hudgins LC, Toib D, Ashraf AP, Song W, Murakami M, Nakajima K, Ploug M, Fong LG, Young SG, Beigneux AP. Chylomicronemia from GPIHBP1 autoantibodies. J Lipid Res 2020; 61:1365-1376. [PMID: 32948662 PMCID: PMC7604722 DOI: 10.1194/jlr.r120001116] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Some cases of chylomicronemia are caused by autoantibodies against glycosylphosphatidylinositol-anchored HDL binding protein 1 (GPIHBP1), an endothelial cell protein that shuttles LPL to the capillary lumen. GPIHBP1 autoantibodies prevent binding and transport of LPL by GPIHBP1, thereby disrupting the lipolytic processing of triglyceride-rich lipoproteins. Here, we review the "GPIHBP1 autoantibody syndrome" and summarize clinical and laboratory findings in 22 patients. All patients had GPIHBP1 autoantibodies and chylomicronemia, but we did not find a correlation between triglyceride levels and autoantibody levels. Many of the patients had a history of pancreatitis, and most had clinical and/or serological evidence of autoimmune disease. IgA autoantibodies were present in all patients, and IgG4 autoantibodies were present in 19 of 22 patients. Patients with GPIHBP1 autoantibodies had low plasma LPL levels, consistent with impaired delivery of LPL into capillaries. Plasma levels of GPIHBP1, measured with a monoclonal antibody-based ELISA, were very low in 17 patients, reflecting the inability of the ELISA to detect GPIHBP1 in the presence of autoantibodies (immunoassay interference). However, GPIHBP1 levels were very high in five patients, indicating little capacity of their autoantibodies to interfere with the ELISA. Recently, several GPIHBP1 autoantibody syndrome patients were treated successfully with rituximab, resulting in the disappearance of GPIHBP1 autoantibodies and normalization of both plasma triglyceride and LPL levels. The GPIHBP1 autoantibody syndrome should be considered in any patient with newly acquired and unexplained chylomicronemia.
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Affiliation(s)
- Kazuya Miyashita
- Department of Clinical Laboratory Medicine, Gunma University, Graduate School of Medicine, Maebashi, Japan
- Immuno-Biological Laboratories (IBL), Fujioka, Gunma, Japan
| | - Jens Lutz
- Medical Clinic, Nephrology-Infectious Diseases, Central Rhine Hospital Group, Koblenz, Germany
| | - Lisa C Hudgins
- Rogosin Institute, Weill Cornell Medical College, New York, NY, USA
| | - Dana Toib
- Department of Pediatrics, Drexel University, Philadelphia, PA, USA
- Section of Pediatric Rheumatology, St. Christopher's Hospital for Children, Philadelphia, PA, USA
| | - Ambika P Ashraf
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Wenxin Song
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Masami Murakami
- Department of Clinical Laboratory Medicine, Gunma University, Graduate School of Medicine, Maebashi, Japan
| | - Katsuyuki Nakajima
- Department of Clinical Laboratory Medicine, Gunma University, Graduate School of Medicine, Maebashi, Japan
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark
- Biotechnology Research Innovation Center, Copenhagen University, Copenhagen, Denmark
| | - Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Anne P Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
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12
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Unfolding of monomeric lipoprotein lipase by ANGPTL4: Insight into the regulation of plasma triglyceride metabolism. Proc Natl Acad Sci U S A 2020; 117:4337-4346. [PMID: 32034094 DOI: 10.1073/pnas.1920202117] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The binding of lipoprotein lipase (LPL) to GPIHBP1 focuses the intravascular hydrolysis of triglyceride-rich lipoproteins on the surface of capillary endothelial cells. This process provides essential lipid nutrients for vital tissues (e.g., heart, skeletal muscle, and adipose tissue). Deficiencies in either LPL or GPIHBP1 impair triglyceride hydrolysis, resulting in severe hypertriglyceridemia. The activity of LPL in tissues is regulated by angiopoietin-like proteins 3, 4, and 8 (ANGPTL). Dogma has held that these ANGPTLs inactivate LPL by converting LPL homodimers into monomers, rendering them highly susceptible to spontaneous unfolding and loss of enzymatic activity. Here, we show that binding of an LPL-specific monoclonal antibody (5D2) to the tryptophan-rich lipid-binding loop in the carboxyl terminus of LPL prevents homodimer formation and forces LPL into a monomeric state. Of note, 5D2-bound LPL monomers are as stable as LPL homodimers (i.e., they are not more prone to unfolding), but they remain highly susceptible to ANGPTL4-catalyzed unfolding and inactivation. Binding of GPIHBP1 to LPL alone or to 5D2-bound LPL counteracts ANGPTL4-mediated unfolding of LPL. In conclusion, ANGPTL4-mediated inactivation of LPL, accomplished by catalyzing the unfolding of LPL, does not require the conversion of LPL homodimers into monomers. Thus, our findings necessitate changes to long-standing dogma on mechanisms for LPL inactivation by ANGPTL proteins. At the same time, our findings align well with insights into LPL function from the recent crystal structure of the LPL•GPIHBP1 complex.
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Ariza MJ, Pérez-López C, Almagro F, Sánchez-Tévar AM, Muñiz-Grijalvo O, Álvarez-Sala Walter LA, Rioja J, Sánchez-Chaparro MÁ, Valdivielso P. Genetic variants in the LPL and GPIHBP1 genes, in patients with severe hypertriglyceridaemia, detected with high resolution melting analysis. Clin Chim Acta 2019; 500:163-171. [PMID: 31669931 DOI: 10.1016/j.cca.2019.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/02/2019] [Accepted: 10/14/2019] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Pathogenic variants in lipoprotein lipase (LPL) and glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) have been described in patients with severe hypertriglyceridaemia. We aimed to optimise high resolution melting (HRM) assays to detect the presence of functional variants in these genes. METHODS One hundred and sixteen patients with severe hypertriglyceridaemia were studied. HRM assays were optimised to scan exons and splice junctions in LPL and GPIHBP1. Sanger sequencing was the reference method. Next-generation-sequencing (NGS) was performed in five patients, including one with Familial Chylomicronemia syndrome (FCS). RESULTS We identified 15 different variants in LPL and 6 in GPIHBP1. The variants revealed with NGS were also detected with HRM, including a rare premature stop codon in LPL (p.Trp421*) and two LPL pathogenic variants in the patient with FCS (p.His80Arg + p.Gly215Glu). Having multiple functional variant alleles was associated with pancreatitis onset at younger ages and higher baseline triglycerides. CONCLUSIONS Our HRM assays detected the presence of functional gene variants that were confirmed with Sanger and NGS sequencing. The presence of multiple functional variant alleles was associated with differences in the clinical profile. Therefore, these assays represent a reliable, cost-effective tool that can be used to complement the NGS approach for gene scanning.
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Affiliation(s)
- María José Ariza
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, Centro de Investigaciones Médico Sanitarias (CIMES), Instituto de Investigación Biomédica de Málaga (IBIMA), University of Málaga, C/Marqués de Beccaria n° 3, 29010 Málaga, Spain.
| | - Carmen Pérez-López
- Internal Medicine Unit, University Hospital Virgen de la Victoria, Campus de Teatinos, S/N, 29010 Málaga, Spain
| | - Fátima Almagro
- Lipids Unit, Internal Medicine, University Hospital Donostia, San Sebastian, Begiristain Doktorea Pasealekua, 107-115, 20014 Donostia, Gipuzkoa, Spain
| | - Ana María Sánchez-Tévar
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, Centro de Investigaciones Médico Sanitarias (CIMES), Instituto de Investigación Biomédica de Málaga (IBIMA), University of Málaga, C/Marqués de Beccaria n° 3, 29010 Málaga, Spain
| | - Ovidio Muñiz-Grijalvo
- UCERV-UCAMI, Internal Medicine Department, University Hospital Virgen del Rocío, Av. Manuel Siurot, S/n, 41013 Sevilla, Spain
| | - Luis Antonio Álvarez-Sala Walter
- Lipids Unit, Internal Medicine, Hospital General Universitario Gregorio Marañón, IiSGM, Calle del Dr. Esquerdo, 46, 28007 Madrid, Spain; Department of Medicine, School of Medicine, Universidad Complutense, Av. Séneca, 2, 28040 Madrid, Spain
| | - José Rioja
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, Centro de Investigaciones Médico Sanitarias (CIMES), Instituto de Investigación Biomédica de Málaga (IBIMA), University of Málaga, C/Marqués de Beccaria n° 3, 29010 Málaga, Spain
| | - Miguel Ángel Sánchez-Chaparro
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, Centro de Investigaciones Médico Sanitarias (CIMES), Instituto de Investigación Biomédica de Málaga (IBIMA), University of Málaga, C/Marqués de Beccaria n° 3, 29010 Málaga, Spain; Internal Medicine Unit, University Hospital Virgen de la Victoria, Campus de Teatinos, S/N, 29010 Málaga, Spain
| | - Pedro Valdivielso
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, Centro de Investigaciones Médico Sanitarias (CIMES), Instituto de Investigación Biomédica de Málaga (IBIMA), University of Málaga, C/Marqués de Beccaria n° 3, 29010 Málaga, Spain; Internal Medicine Unit, University Hospital Virgen de la Victoria, Campus de Teatinos, S/N, 29010 Málaga, Spain
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Zhang Y, He W, He C, Wan J, Lin X, Zheng X, Li L, Li X, Yang X, Yu B, Xian X, Zhu Y, Wang Y, Liu G, Lu N. Large triglyceride-rich lipoproteins in hypertriglyceridemia are associated with the severity of acute pancreatitis in experimental mice. Cell Death Dis 2019; 10:728. [PMID: 31570698 PMCID: PMC6768872 DOI: 10.1038/s41419-019-1969-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/20/2019] [Accepted: 08/26/2019] [Indexed: 02/07/2023]
Abstract
Hypertriglyceridemia severity is linked to acute pancreatitis prognosis, but it remains unknown why a portion of severe hypertriglyceridemia patients do not develop severe acute pancreatitis. To investigate whether hypertriglyceridemia subtypes affect acute pancreatitis progression, we analyzed two genetically modified hypertriglyceridemia mouse models—namely, glycosylphosphatidylinositol high-density lipoprotein binding protein 1 knockout (Gpihbp1−/−) and apolipoprotein C3 transgenic (ApoC3-tg) mice. Acute pancreatitis was induced by 10 intraperitoneal caerulein injections. Biochemical assays and pathological analysis were performed for the severity evaluation of acute pancreatitis. Plasma triglyceride-rich lipoproteins (TRLs), including chylomicrons and very low-density lipoprotein (VLDL), were collected via ultracentrifugation to evaluate their cytotoxic effects on primary pancreatic acinar cells (PACs). We found that the particle sizes of Gpihbp1−/− TRLs were larger than ApoC3-tg TRLs. Severe pancreatic injury with large areas of pancreatic necrosis in the entire lobule was induced in Gpihbp1−/− mice when plasma triglyceride levels were greater than 2000 mg/dL. However, ApoC3-tg mice with the same triglyceride levels did not develop large areas of pancreatic necrosis, even upon the administration of poloxamer 407 to further increase triglyceride levels. Meanwhile, in the acute pancreatitis model, free fatty acids (FFAs) in the pancreas of Gpihbp1−/− mice were greater than in ApoC3-tg mice. TRLs from Gpihbp1−/− mice released more FFAs and were more toxic to PACs than those from ApoC3-tg mice. Chylomicrons from patients showed the same effects on PACs as TRLs from Gpihbp1−/− mice. Gpihbp1−/− mice with triglyceride levels below 2000 mg/dL had milder pancreatic injury and less incidence of pancreatic necrosis than those with triglyceride levels above 2000 mg/dL, similar to Gpihbp1−/−mice with triglyceride levels above 2000 mg/dL but with fenofibrate administration. These findings demonstrated that hypertriglyceridemia subtypes with large TRL particles could affect acute pancreatitis progression and that chylomicrons showed more cytotoxicity than VLDL by releasing more FFAs.
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Affiliation(s)
- Yue Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Wenhua He
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Cong He
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Jianhua Wan
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Xiao Lin
- Institute of Cardiovascular Sciences, Peking University Health Science Center, 100191, Beijing, China.,Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, 100191, Beijing, China
| | - Xi Zheng
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Lei Li
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Xueyang Li
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Xiaoyu Yang
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Bingjun Yu
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Xunde Xian
- Institute of Cardiovascular Sciences, Peking University Health Science Center, 100191, Beijing, China.,Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, 100191, Beijing, China
| | - Yin Zhu
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China
| | - Yuhui Wang
- Institute of Cardiovascular Sciences, Peking University Health Science Center, 100191, Beijing, China. .,Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, 100191, Beijing, China.
| | - George Liu
- Institute of Cardiovascular Sciences, Peking University Health Science Center, 100191, Beijing, China.,Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, 100191, Beijing, China
| | - Nonghua Lu
- Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, 330006, Nanchang, China.
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15
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Young SG, Fong LG, Beigneux AP, Allan CM, He C, Jiang H, Nakajima K, Meiyappan M, Birrane G, Ploug M. GPIHBP1 and Lipoprotein Lipase, Partners in Plasma Triglyceride Metabolism. Cell Metab 2019; 30:51-65. [PMID: 31269429 PMCID: PMC6662658 DOI: 10.1016/j.cmet.2019.05.023] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Lipoprotein lipase (LPL), identified in the 1950s, has been studied intensively by biochemists, physiologists, and clinical investigators. These efforts uncovered a central role for LPL in plasma triglyceride metabolism and identified LPL mutations as a cause of hypertriglyceridemia. By the 1990s, with an outline for plasma triglyceride metabolism established, interest in triglyceride metabolism waned. In recent years, however, interest in plasma triglyceride metabolism has awakened, in part because of the discovery of new molecules governing triglyceride metabolism. One such protein-and the focus of this review-is GPIHBP1, a protein of capillary endothelial cells. GPIHBP1 is LPL's essential partner: it binds LPL and transports it to the capillary lumen; it is essential for lipoprotein margination along capillaries, allowing lipolysis to proceed; and it preserves LPL's structure and activity. Recently, GPIHBP1 was the key to solving the structure of LPL. These developments have transformed the models for intravascular triglyceride metabolism.
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Affiliation(s)
- Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Anne P Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Christopher M Allan
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Cuiwen He
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Haibo Jiang
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; School of Molecular Sciences, University of Western Australia, Crawley 6009, Australia
| | - Katsuyuki Nakajima
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Department of Medicine, Maebashi, Gunma 371-0805, Japan
| | - Muthuraman Meiyappan
- Discovery Therapeutics, Takeda Pharmaceutical Company Ltd., Cambridge, MA 02142, USA
| | - Gabriel Birrane
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, Copenhagen DK-2200, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen DK-2200, Denmark.
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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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17
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Chen LY, Xia XD, Zhao ZW, Gong D, Ma XF, Yu XH, Zhang Q, Wang SQ, Dai XY, Zheng XL, Zhang DW, Yin WD, Tang CK. MicroRNA-377 Inhibits Atherosclerosis by Regulating Triglyceride Metabolism Through the DNA Methyltransferase 1 in Apolipoprotein E-Knockout Mice. Circ J 2018; 82:2861-2871. [PMID: 30232292 DOI: 10.1253/circj.cj-18-0410] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Lipoprotein lipase (LPL) plays an important role in triglyceride metabolism. It is translocated across endothelial cells to reach the luminal surface of capillaries by glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1), where it hydrolyzes triglycerides in lipoproteins. MicroRNA 377 (miR-377) is highly associated with lipid levels. However, how miR-377 regulates triglyceride metabolism and whether it is involved in the development of atherosclerosis remain largely unexplored. Methods and Results: The clinical examination displayed that miR-377 expression was markedly lower in plasma from patients with hypertriglyceridemia compared with non-hypertriglyceridemic subjects. Bioinformatics analyses and a luciferase reporter assay showed that DNA methyltransferase 1 (DNMT1) was a target gene of miR-377. Moreover, miR-377 increased LPL binding to GPIHBP1 by directly targeting DNMT1 in human umbilical vein endothelial cells (HUVECs) and apolipoprotein E (ApoE)-knockout (KO) mice aorta endothelial cells (MAECs). In vivo, hematoxylin-eosin (H&E), Oil Red O and Masson's trichrome staining showed that ApoE-KO mice treated with miR-377 developed less atherosclerotic plaques, accompanied by reduced plasma triglyceride levels. CONCLUSIONS It is concluded that miR-377 upregulates GPIHBP1 expression, increases the LPL binding to GPIHBP1, and reduces plasma triglyceride levels, likely through targeting DNMT1, inhibiting atherosclerosis in ApoE-KO mice.
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Affiliation(s)
- Ling-Yan Chen
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Xiao-Dan Xia
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Zhen-Wang Zhao
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Duo Gong
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Xiao-Feng Ma
- Department of Internal Medicine-Cardiovascular, Nanhua Hospital, University of South China
| | - Xiao-Hua Yu
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Qiang Zhang
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Si-Qi Wang
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Xiao-Yan Dai
- Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou, Medical University
| | - Xi-Long Zheng
- Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Health Sciences Center
| | - Da-Wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, University of Alberta
| | - Wei-Dong Yin
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Chao-Ke Tang
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Medical Research Center, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
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Liu C, Li L, Guo D, Lv Y, Zheng X, Mo Z, Xie W. Lipoprotein lipase transporter GPIHBP1 and triglyceride-rich lipoprotein metabolism. Clin Chim Acta 2018; 487:33-40. [PMID: 30218660 DOI: 10.1016/j.cca.2018.09.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/11/2018] [Accepted: 09/11/2018] [Indexed: 02/05/2023]
Abstract
Increased plasma triglyceride serves as an independent risk factor for cardiovascular disease (CVD). Lipoprotein lipase (LPL), which hydrolyzes circulating triglyceride, plays a crucial role in normal lipid metabolism and energy balance. Hypertriglyceridemia is possibly caused by gene mutations resulting in LPL dysfunction. There are many factors that both positively and negatively interact with LPL thereby impacting TG lipolysis. Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), a newly identified factor, appears essential for transporting LPL to the luminal side of the blood vessel and offering a platform for TG hydrolysis. Numerous lines of evidence indicate that GPIHBP1 exerts distinct functions and plays diverse roles in human triglyceride-rich lipoprotein (TRL) metabolism. In this review, we discuss the GPIHBP1 gene, protein, its expression and function and subsequently focus on its regulation and provide critical evidence supporting its role in TRL metabolism. Underlying mechanisms of action are highlighted, additional studies discussed and potential therapeutic targets reviewed.
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Affiliation(s)
- Chuhao Liu
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China; 2016 Class of Excellent Doctor, University of South China, Hengyang 421001, Hunan, China
| | - Liang Li
- Department of Pathophysiology, University of South China, Hengyang 421001, Hunan, China
| | - Dongming Guo
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China
| | - Yuncheng Lv
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China
| | - XiLong Zheng
- Department of Biochemistry and Molecular Biology, The Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, The University of Calgary, Health Sciences Center, 3330 Hospital Dr NW, Calgary T2N 4N1, Alberta, Canada; Key Laboratory of Molecular Targets & Clinical Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, Guangdong, China
| | - Zhongcheng Mo
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China.
| | - Wei Xie
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China.
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GPIHBP1 autoantibodies in a patient with unexplained chylomicronemia. J Clin Lipidol 2017; 11:964-971. [PMID: 28666713 DOI: 10.1016/j.jacl.2017.05.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 05/23/2017] [Indexed: 12/28/2022]
Abstract
BACKGROUND GPIHBP1, a glycolipid-anchored protein of capillary endothelial cells, binds lipoprotein lipase (LPL) in the interstitial spaces and transports it to the capillary lumen. GPIHBP1 deficiency prevents LPL from reaching the capillary lumen, resulting in low intravascular LPL levels, impaired intravascular triglyceride processing, and severe hypertriglyceridemia (chylomicronemia). A recent study showed that some cases of hypertriglyceridemia are caused by autoantibodies against GPIHBP1 ("GPIHBP1 autoantibody syndrome"). OBJECTIVE Our objective was to gain additional insights into the frequency of the GPIHBP1 autoantibody syndrome in patients with unexplained chylomicronemia. METHODS We used enzyme-linked immunosorbent assays to screen for GPIHBP1 autoantibodies in 33 patients with unexplained chylomicronemia and then used Western blots and immunocytochemistry studies to characterize the GPIHBP1 autoantibodies. RESULTS The plasma of 1 patient, a 36-year-old man with severe hypertriglyceridemia, contained GPIHBP1 autoantibodies. The autoantibodies, which were easily detectable by Western blot, blocked the ability of GPIHBP1 to bind LPL. The plasma levels of LPL mass and activity were low. The patient had no history of autoimmune disease, but his plasma was positive for antinuclear antibodies. CONCLUSIONS One of 33 patients with unexplained chylomicronemia had the GPIHBP1 autoantibody syndrome. Additional studies in large lipid clinics will be helpful for better defining the frequency of this syndrome and for exploring the best strategies for treatment.
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Chen WJ, Sun XF, Zhang RX, Xu MJ, Dou TH, Zhang XB, Zhong M, Yang WQ, Liu L, Lu XY, Zhu CQ. Hypertriglyceridemic acute pancreatitis in emergency department: Typical clinical features and genetic variants. J Dig Dis 2017; 18:359-368. [PMID: 28548292 DOI: 10.1111/1751-2980.12490] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/18/2017] [Accepted: 05/23/2017] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To investigate the clinical characteristics of patients with hypertriglyceridemic acute pancreatitis (HTGAP), and the molecular foundation contributing to hypertriglyceridemia in such patients. METHODS Clinical data from 329 patients with acute pancreatitis (AP) were analyzed. The patients were divided into the HTGAP group, with fasting serum triglyceride (TG) levels ≥500 mg/dL (5.65 mmol/L), and the non-HTGAP (NHTGAP) group. Targeted next-generation sequencing was applied to 11 HTGAP patients to identify the genetic mutations associated with hypertriglyceridemia, including apolipoprotein A-V (APOA5), APOC2, APOC3 and APOE, BLK, LPL, GPIHBP1 and LMF1. RESULTS Patients in the HTGAP group, compared with those in the NHTGAP group, had a higher mortality rate (7.5% vs 0.7%, P = 0.001), more commonly seen severe AP (17.5% vs 5.2%, P = 0.004) as well as a higher recurrence rate (32.4% vs 19.9%, P = 0.070). DNA sequencing showed that two patients carried the same compound of p.G185C and p.V153M heterozygous mutations located in the APOA5 gene. Two patients carried a homozygous variation of p.C14F, in the GPIHBP1 gene. One patient had a homozygous variation of p.R176C in the APOE gene. And a rare heterozygous LMF1 gene mutation of p.P562R was detected in two patients. CONCLUSIONS HTGAP was significantly severe than NHTGAP, with a high recurrence rate. Genetic information may be useful in the clinical setting for the investigation of the pathogenesis of HTGAP and its interventions.
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Affiliation(s)
- Wan Jun Chen
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao Fan Sun
- Outpatient and Emergency Department, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Rui Xue Zhang
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Min Jie Xu
- State Key Laboratory of Genetic Engineering, Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Tong Hai Dou
- State Key Laboratory of Genetic Engineering, Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Xiao Bin Zhang
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Min Zhong
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wei Qiang Yang
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Li Liu
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao Ye Lu
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chang Qing Zhu
- Department of Emergency Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Mysling S, Kristensen KK, Larsson M, Kovrov O, Bensadouen A, Jørgensen TJ, Olivecrona G, Young SG, Ploug M. The angiopoietin-like protein ANGPTL4 catalyzes unfolding of the hydrolase domain in lipoprotein lipase and the endothelial membrane protein GPIHBP1 counteracts this unfolding. eLife 2016; 5. [PMID: 27929370 PMCID: PMC5148603 DOI: 10.7554/elife.20958] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/14/2016] [Indexed: 01/08/2023] Open
Abstract
Lipoprotein lipase (LPL) undergoes spontaneous inactivation via global unfolding and this unfolding is prevented by GPIHBP1 (Mysling et al., 2016). We now show: (1) that ANGPTL4 inactivates LPL by catalyzing the unfolding of its hydrolase domain; (2) that binding to GPIHBP1 renders LPL largely refractory to this inhibition; and (3) that both the LU domain and the intrinsically disordered acidic domain of GPIHBP1 are required for this protective effect. Genetic studies have found that a common polymorphic variant in ANGPTL4 results in lower plasma triglyceride levels. We now report: (1) that this ANGPTL4 variant is less efficient in catalyzing the unfolding of LPL; and (2) that its Glu-to-Lys substitution destabilizes its N-terminal α-helix. Our work elucidates the molecular basis for regulation of LPL activity by ANGPTL4, highlights the physiological relevance of the inherent instability of LPL, and sheds light on the molecular defects in a clinically relevant variant of ANGPTL4. DOI:http://dx.doi.org/10.7554/eLife.20958.001
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Affiliation(s)
- Simon Mysling
- Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark.,Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.,Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Kristian Kølby Kristensen
- Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark.,Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
| | - Mikael Larsson
- Department of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Oleg Kovrov
- Department of Medical Biosciences, Umeå University, Umeå, Sweden
| | - André Bensadouen
- Division of Nutritional Science, Cornell University, Ithaca, United States
| | - Thomas Jd Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | - Stephen G Young
- Department of Medicine, University of California, Los Angeles, Los Angeles, United States.,Department of Human Genetics, University of California, Los Angeles, Los Angeles, United States
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark.,Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
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22
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Allan CM, Larsson M, Jung RS, Ploug M, Bensadoun A, Beigneux AP, Fong LG, Young SG. Mobility of "HSPG-bound" LPL explains how LPL is able to reach GPIHBP1 on capillaries. J Lipid Res 2016; 58:216-225. [PMID: 27811232 DOI: 10.1194/jlr.m072520] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 10/31/2016] [Indexed: 12/22/2022] Open
Abstract
In mice lacking glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1), the LPL secreted by adipocytes and myocytes remains bound to heparan sulfate proteoglycans (HSPGs) on all cells within tissues. That observation raises a perplexing issue: Why isn't the freshly secreted LPL in wild-type mice captured by the same HSPGs, thereby preventing LPL from reaching GPIHBP1 on capillaries? We hypothesized that LPL-HSPG interactions are transient, allowing the LPL to detach and move to GPIHBP1 on capillaries. Indeed, we found that LPL detaches from HSPGs on cultured cells and moves to: 1) soluble GPIHBP1 in the cell culture medium; 2) GPIHBP1-coated agarose beads; and 3) nearby GPIHBP1-expressing cells. Movement of HSPG-bound LPL to GPIHBP1 did not occur when GPIHBP1 contained a Ly6 domain missense mutation (W109S), but was almost normal when GPIHBP1's acidic domain was mutated. To test the mobility of HSPG-bound LPL in vivo, we injected GPIHBP1-coated agarose beads into the brown adipose tissue of GPIHBP1-deficient mice. LPL moved quickly from HSPGs on adipocytes to GPIHBP1-coated beads, thereby depleting LPL stores on the surface of adipocytes. We conclude that HSPG-bound LPL in the interstitial spaces of tissues is mobile, allowing the LPL to move to GPIHBP1 on endothelial cells.
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Affiliation(s)
- Christopher M Allan
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Mikael Larsson
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Rachel S Jung
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, DK-2200 Copenhagen N, Denmark and Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK-220 Copenhagen N, Denmark
| | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY 14853
| | - Anne P Beigneux
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Loren G Fong
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Stephen G Young
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095 .,Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
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23
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Allan CM, Larsson M, Hu X, He C, Jung RS, Mapar A, Voss C, Miyashita K, Machida T, Murakami M, Nakajima K, Bensadoun A, Ploug M, Fong LG, Young SG, Beigneux AP. An LPL-specific monoclonal antibody, 88B8, that abolishes the binding of LPL to GPIHBP1. J Lipid Res 2016; 57:1889-1898. [PMID: 27494936 DOI: 10.1194/jlr.m070813] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Indexed: 12/26/2022] Open
Abstract
LPL contains two principal domains: an amino-terminal catalytic domain (residues 1-297) and a carboxyl-terminal domain (residues 298-448) that is important for binding lipids and binding glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1) (an endothelial cell protein that shuttles LPL to the capillary lumen). The LPL sequences required for GPIHBP1 binding have not been examined in detail, but one study suggested that sequences near LPL's carboxyl terminus (residues ∼403-438) were crucial. Here, we tested the ability of LPL-specific monoclonal antibodies (mAbs) to block the binding of LPL to GPIHBP1. One antibody, 88B8, abolished LPL binding to GPIHBP1. Consistent with those results, antibody 88B8 could not bind to GPIHBP1-bound LPL on cultured cells. Antibody 88B8 bound poorly to LPL proteins with amino acid substitutions that interfered with GPIHBP1 binding (e.g., C418Y, E421K). However, the sequences near LPL's carboxyl terminus (residues ∼403-438) were not sufficient for 88B8 binding; upstream sequences (residues 298-400) were also required. Additional studies showed that these same sequences are required for LPL binding to GPIHBP1. In conclusion, we identified an LPL mAb that binds to LPL's GPIHBP1-binding domain. The binding of both antibody 88B8 and GPIHBP1 to LPL depends on large segments of LPL's carboxyl-terminal domain.
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Affiliation(s)
- Christopher M Allan
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Mikael Larsson
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Xuchen Hu
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Cuiwen He
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Rachel S Jung
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Alaleh Mapar
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Constance Voss
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | | | - Tetsuo Machida
- Gunma University, Graduate School of Medicine, Maebashi, Japan
| | - Masami Murakami
- Gunma University, Graduate School of Medicine, Maebashi, Japan
| | | | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, Copenhagen N, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen N, Denmark
| | - Loren G Fong
- Departments of Medicine University of California Los Angeles, Los Angeles, CA.
| | - Stephen G Young
- Departments of Medicine University of California Los Angeles, Los Angeles, CA; Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA.
| | - Anne P Beigneux
- Departments of Medicine University of California Los Angeles, Los Angeles, CA.
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24
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Fong LG, Young SG, Beigneux AP, Bensadoun A, Oberer M, Jiang H, Ploug M. GPIHBP1 and Plasma Triglyceride Metabolism. Trends Endocrinol Metab 2016; 27:455-469. [PMID: 27185325 PMCID: PMC4927088 DOI: 10.1016/j.tem.2016.04.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 10/21/2022]
Abstract
GPIHBP1, a GPI-anchored protein in capillary endothelial cells, is crucial for the lipolytic processing of triglyceride-rich lipoproteins (TRLs). GPIHBP1 shuttles lipoprotein lipase (LPL) to its site of action in the capillary lumen and is essential for the margination of TRLs along capillaries - such that lipolytic processing can proceed. GPIHBP1 also reduces the unfolding of the LPL catalytic domain, thereby stabilizing LPL catalytic activity. Many different GPIHBP1 mutations have been identified in patients with severe hypertriglyceridemia (chylomicronemia), the majority of which interfere with folding of the protein and abolish its capacity to bind and transport LPL. The discovery of GPIHBP1 has substantially revised our understanding of intravascular triglyceride metabolism but has also raised many new questions for future research.
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Affiliation(s)
- Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
| | - Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
| | - Anne P Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY 14853, USA
| | - Monika Oberer
- Institute of Molecular Biosciences, University of Graz and BioTechMed, Graz, Austria
| | - Haibo Jiang
- Centre for Microscopy, Characterisation, and Analysis, The University of Western Australia
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, 2200 Copenhagen N, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 220 Copenhagen N, Denmark.
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25
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Clinical and genetic features of 3 patients with familial chylomicronemia due to mutations in GPIHBP1 gene. J Clin Lipidol 2016; 10:915-921.e4. [PMID: 27578123 DOI: 10.1016/j.jacl.2016.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Familial chylomicronemia is a recessive disorder that may be due to mutations in lipoprotein lipase (LPL) and in other proteins such as apolipoprotein C-II and apolipoprotein A-V (activators of LPL), GPIHBP1 (the molecular platform required for LPL activity on endothelial surface), and LMF1 (a factor required for intracellular formation of active LPL). METHODS We sequenced the familial chylomicronemia candidate genes in 2 adult females presenting long-standing hypertriglyceridemia and a history of acute pancreatitis. RESULTS Both probands had plasma triglyceride >10 mmol/L but no mutations in the LPL gene. The sequence of the other candidate genes showed that one patient was homozygous for a novel missense mutation p.(Cys83Arg), and the other was homozygous for a previously reported nonsense mutation p.(Cys 89*), respectively, in GPIHBP1. Family screening showed that the hypertriglyceridemic brother of the p.(Cys83Arg) homozygote was also homozygous for this mutation. He had no history of pancreatitis. The p.(Cys83Arg) heterozygous carriers had normal triglyceride levels. The substitution of a cysteine residue in the Ly6 domain of GPIHBP1 is predicted to abolish one of the disulfide bridges required to maintain the structure of GPIHBP1. The p.(Cys89*) mutation results in a truncated protein devoid of function. CONCLUSIONS Both mutant GPIHBP1 proteins are expected to be incapable of transferring LPL from the subendothelial space to the endothelial surface.
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