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Wang S, Cheng Y, Shi Y, Zhao W, Gao L, Fang L, Jin X, Han X, Sun Q, Li G, Zhao J, Xu C. Identification and Characterization of Two Novel Compounds: Heterozygous Variants of Lipoprotein Lipase in Two Pedigrees With Type I Hyperlipoproteinemia. Front Endocrinol (Lausanne) 2022; 13:874608. [PMID: 35923617 PMCID: PMC9339609 DOI: 10.3389/fendo.2022.874608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 06/03/2022] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Type I hyperlipoproteinemia, characterized by severe hypertriglyceridemia, is caused mainly by loss-of-function mutation of the lipoprotein lipase (LPL) gene. To date, more than 200 mutations in the LPL gene have been reported, while only a limited number of mutations have been evaluated for pathogenesis. OBJECTIVE This study aims to explore the molecular mechanisms underlying lipoprotein lipase deficiency in two pedigrees with type 1 hyperlipoproteinemia. METHODS We conducted a systematic clinical and genetic analysis of two pedigrees with type 1 hyperlipoproteinemia. Postheparin plasma of all the members was used for the LPL activity analysis. In vitro studies were performed in HEK-293T cells that were transiently transfected with wild-type or variant LPL plasmids. Furthermore, the production and activity of LPL were analyzed in cell lysates or culture medium. RESULTS Proband 1 developed acute pancreatitis in youth, and her serum triglycerides (TGs) continued to be at an ultrahigh level, despite the application of various lipid-lowering drugs. Proband 2 was diagnosed with type 1 hyperlipoproteinemia at 9 months of age, and his serum TG levels were mildly elevated with treatment. Two novel compound heterozygous variants of LPL (c.3G>C, p. M1? and c.835_836delCT, p. L279Vfs*3, c.188C>T, p. Ser63Phe and c.662T>C, p. Ile221Thr) were identified in the two probands. The postheparin LPL activity of probands 1 and 2 showed decreases of 72.22 ± 9.46% (p<0.01) and 54.60 ± 9.03% (p<0.01), respectively, compared with the control. In vitro studies showed a substantial reduction in the expression or enzyme activity of LPL in the LPL variants. CONCLUSIONS Two novel compound heterozygous variants of LPL induced defects in the expression and function of LPL and caused type I hyperlipoproteinemia. The functional characterization of these variants was in keeping with the postulated LPL mutant activity.
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Affiliation(s)
- Shuping Wang
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Endocrinology and Metabolism, Dongying People’s Hospital, Dongying, China
| | - Yiping Cheng
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Yingzhou Shi
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Wanyi Zhao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Ling Gao
- Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Shandong Clinical Research Center of Diabetes and Metabolic Diseases, Jinan, China
- Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, China
- Shandong Prevention and Control Engineering Laboratory of Endocrine and Metabolic Diseases, Jinan, China
| | - Li Fang
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Xiaolong Jin
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Xiaoyan Han
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Qiuying Sun
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Guimei Li
- Department of Pediatrics, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China
- *Correspondence: Jiajun Zhao, ; Guimei Li, ; Chao Xu,
| | - Jiajun Zhao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- *Correspondence: Jiajun Zhao, ; Guimei Li, ; Chao Xu,
| | - Chao Xu
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- *Correspondence: Jiajun Zhao, ; Guimei Li, ; Chao Xu,
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Qin YY, Wei AQ, Shan QW, Xian XY, Wu YY, Liao L, Yan J, Lai ZF, Lin FQ. Rare LPL gene missense mutation in an infant with hypertriglyceridemia. J Clin Lab Anal 2018; 32:e22414. [PMID: 29479812 DOI: 10.1002/jcla.22414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 01/27/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Severe hypertriglyceridemia usually results from a combination of genetic and environmental factors and is most often attributable to mutations in the lipoprotein lipase (LPL) gene. OBJECTIVES The aim of this study was to identify rare mutations in the LPL gene causing severe hypertriglyceridemia. METHODS A Chinese infant who presented classical features of severe hypertriglyceridemia recruited for DNA sequencing of the LPL gene. The pathogenicity grade of the variants was defined based on the prediction of pathogenicity using in silico prediction tools. Review some studies to understand the molecular mechanisms underlying the severe hypertriglyceridemia. RESULTS We identified a rare mutation in the LPL gene causing severe hypertriglyceridemia: a nucleotide substitution (c.836T>G) resulting in a leucine to arginine substitution at position 279 of the protein (p.Leu279Arg).The pathogenicity of the variant was predicted by in silico analysis using PolyPhen2 and SIFT prediction programs, which indicated that mutation p.Leu279Arg is probably harmful. We have also reviewed published studies concerning the molecular mechanisms underlying severe hypertriglyceridemia. A missense mutation in the 6 exon of the LPL gene is reportedly associated with LPL deficiency. CONCLUSIONS We have here identified a rare pathogenic mutation in the LPL gene in a Chinese infant with severe hypertriglyceridemia.
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Affiliation(s)
- Yuan-Yuan Qin
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Ai-Qiu Wei
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Qing-Wen Shan
- Department of pediatric, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Xiao-Ying Xian
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Yang-Yang Wu
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Lin Liao
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jie Yan
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Zhan-Feng Lai
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Fa-Quan Lin
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
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Abstract
Lipoprotein lipase (LPL) is a multifunctional enzyme produced by many tissues, including adipose tissue, cardiac and skeletal muscle, islets, and macrophages. LPL is the rate-limiting enzyme for the hydrolysis of the triglyceride (TG) core of circulating TG-rich lipoproteins, chylomicrons, and very low-density lipoproteins (VLDL). LPL-catalyzed reaction products, fatty acids, and monoacylglycerol are in part taken up by the tissues locally and processed differentially; e.g., they are stored as neutral lipids in adipose tissue, oxidized, or stored in skeletal and cardiac muscle or as cholesteryl ester and TG in macrophages. LPL is regulated at transcriptional, posttranscriptional, and posttranslational levels in a tissue-specific manner. Nutrient states and hormonal levels all have divergent effects on the regulation of LPL, and a variety of proteins that interact with LPL to regulate its tissue-specific activity have also been identified. To examine this divergent regulation further, transgenic and knockout murine models of tissue-specific LPL expression have been developed. Mice with overexpression of LPL in skeletal muscle accumulate TG in muscle, develop insulin resistance, are protected from excessive weight gain, and increase their metabolic rate in the cold. Mice with LPL deletion in skeletal muscle have reduced TG accumulation and increased insulin action on glucose transport in muscle. Ultimately, this leads to increased lipid partitioning to other tissues, insulin resistance, and obesity. Mice with LPL deletion in the heart develop hypertriglyceridemia and cardiac dysfunction. The fact that the heart depends increasingly on glucose implies that free fatty acids are not a sufficient fuel for optimal cardiac function. Overall, LPL is a fascinating enzyme that contributes in a pronounced way to normal lipoprotein metabolism, tissue-specific substrate delivery and utilization, and the many aspects of obesity and other metabolic disorders that relate to energy balance, insulin action, and body weight regulation.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045, USA
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