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Mitochondrial function in immature bovine oocytes is improved by an increase of cellular cyclic AMP. Sci Rep 2019; 9:5167. [PMID: 30914704 PMCID: PMC6435665 DOI: 10.1038/s41598-019-41610-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 03/11/2019] [Indexed: 11/08/2022] Open
Abstract
Although in vitro maturation (IVM) of oocytes is important for assisted reproduction, the rate of development of embryos from IVM oocytes is lower than from their in vivo counterparts. It has been shown that an artificial increase of intracellular cAMP before culture significantly improves oocyte developmental competence in cattle and mice. Here, we revealed that forskolin and 3-isobutyl-1-methylxanthine treatment of prophase-stage oocytes induced the expression of genes required for glycolysis, fatty acid degradation, and the mitochondrial electron transport system and improved mitochondrial functions and ATP levels in oocytes without involving nuclear maturation. We propose the existence of a comprehensive energy-supply system in oocytes under follicle-stimulating hormone stimulation as a potential explanation of how oocytes acquire developmental competence.
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Balbuena-Pecino S, Riera-Heredia N, Vélez EJ, Gutiérrez J, Navarro I, Riera-Codina M, Capilla E. Temperature Affects Musculoskeletal Development and Muscle Lipid Metabolism of Gilthead Sea Bream ( Sparus aurata). Front Endocrinol (Lausanne) 2019; 10:173. [PMID: 30967839 PMCID: PMC6439310 DOI: 10.3389/fendo.2019.00173] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/01/2019] [Indexed: 12/12/2022] Open
Abstract
World population is expected to increase to approximately 9 thousand million people by 2050 with a consequent food security decline. Besides, climate change is a major challenge that humanity is facing, with a predicted rise in mean sea surface temperature of more than 2°C during this century. This study aims to determine whether a rearing temperature of 19, 24, or 28°C may influence musculoskeletal development and muscle lipid metabolism in gilthead sea bream juveniles. The expression of growth hormone (GH)/insulin-like growth factors (IGFs) system-, osteogenic-, myogenic-, and lipid metabolism-related genes in bone and/or white muscle of treated fish, and the in vitro viability, mineralization, and osteogenic genes expression in primary cultured cells derived from bone of the same fish were analyzed. The highest temperature significantly down-regulated igf-1, igf-2, the receptor igf-1ra, and the binding proteins igfbp-4 and igfbp-5b in bone, and in muscle, igf-1 and igf-1ra, suggesting impaired musculoskeletal development. Concerning myogenic factors expression, contrary responses were observed, since the increase to 24°C significantly down-regulated myod1 and mrf4, while at 28°C myod2 and myogenin were significantly up-regulated. Moreover, in the muscle tissue, the expression of the fatty acid transporters cd36 and fabp11, and the lipases lipa and lpl-lk resulted significantly increased at elevated temperatures, whereas β-oxidation markers cpt1a and cpt1b were significantly reduced. Regarding the primary cultured bone-derived cells, a significant up-regulation of the extracellular matrix proteins on, op, and ocn expression was found with increased temperatures, together with a gradual decrease in mineralization along with fish rearing temperature. Overall, these results suggest that increasing water temperature in this species appears to induce unfavorable growth and development of bone and muscle, through modulating the expression of different members of the GH/IGFs axis, myogenic and osteogenic genes, while accelerating the utilization of lipids as an energy source, although less efficiently than at optimal temperatures.
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Affiliation(s)
| | | | | | | | | | | | - Encarnación Capilla
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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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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4
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Characterizing familial chylomicronemia syndrome: Baseline data of the APPROACH study. J Clin Lipidol 2018; 12:1234-1243.e5. [PMID: 30318066 DOI: 10.1016/j.jacl.2018.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/16/2018] [Accepted: 05/22/2018] [Indexed: 12/30/2022]
Abstract
BACKGROUND Familial chylomicronemia syndrome (FCS) is a rare metabolic disorder caused by mutations in lipoprotein lipase (LPL) or genes required for LPL functionality and is characterized by hyperchylomicronemia that results in recurrent episodes of acute pancreatitis. Owing to the rarity of FCS, there are few case series describing the phenotypic variability in FCS patients in detail. OBJECTIVE To provide baseline characteristics in the largest study population to date of patients with FCS. METHODS We analyzed baseline demographic and clinical characteristics of adult FCS patients in the phase 3 APPROACH study of volanesorsen sodium (antisense inhibitor of apolipoprotein C-III). RESULTS Sixty-six patients were included in the analysis. Mean (SD) age was 46 (13) years; and mean body mass index was 24.9 (5.7) kg/m2. We identified causal mutations in 79% (52) of patients, with LPL mutations accounting for 62% (41) of cases. Median age at diagnosis was 24 years, 54% were females, and 81% were Caucasian. All patients followed a low-fat diet, 43% received fibrates, 27% fish oils, and 21% statins. Median fasting triglyceride levels (P25, P75) were 1985 (1179, 3047 mg/dL). Overall, 76% of patients reported ≥1 lifetime episode of acute pancreatitis; 23 patients reported a total of 53 pancreatitis events in the 5 years before enrollment. CONCLUSIONS Our data emphasize the severe hypertriglyceridemia characteristic of FCS patients despite restrictive low-fat diets and frequent use of existing hypolipemic therapies. Acute pancreatitis and recurrent acute pancreatitis are frequent complications of FCS. Diagnosis at an older age suggests likely underdiagnosis and underappreciation of this rare disorder.
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An M, Ryu DR, Won Park J, Ha Choi J, Park EM, Eun Lee K, Woo M, Kim M. ULK1 prevents cardiac dysfunction in obesity through autophagy-meditated regulation of lipid metabolism. Cardiovasc Res 2018; 113:1137-1147. [PMID: 28430962 DOI: 10.1093/cvr/cvx064] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 03/23/2017] [Indexed: 11/14/2022] Open
Abstract
Aims Autophagy is essential to maintain tissue homeostasis, particularly in long-lived cells such as cardiomyocytes. Whereas many studies support the importance of autophagy in the mechanisms underlying obesity-related cardiac dysfunction, the role of autophagy in cardiac lipid metabolism remains unclear. In the heart, lipotoxicity is exacerbated by cardiac lipoprotein lipase (LPL), which mediates accumulation of fatty acids to the heart through intravascular triglyceride (TG) hydrolysis. Methods and results In both genetic and dietary models of obesity, we observed a substantial increase in cardiac LPL protein levels without any change in messenger ribonucleic acid (mRNA). This was accompanied by a dramatic down-regulation of autophagy in the heart, as revealed by reduced levels of unc-51 like kinase-1 (ULK1) protein. To further explore the relationship between cardiac LPL and autophagy, we generated cardiomyocyte-specific knockout mice for ulk1 (Myh6-cre/ulk1fl/fl), Lpl (Myh6-cre/Lplfl/fl), and mice with a combined deficiency (Myh6-cre/ulk1fl/flLplfl/fl). Similar to genetic and dietary models of obesity, Myh6-cre/ulk1fl/fl mice had a substantial increase in cardiac LPL levels. When these mice were fed a high-fat diet (HFD), they showed elevated cardiac TG levels and deterioration in heart function. However, with combined deletion of LPL and ULK1 in Myh6-cre/ulk1fl/flLplfl/fl mice, HFD feeding did not lead to alterations in levels of TG or diacylglycerol, or in cardiac function. To further elucidate the role of autophagy in cardiac lipid metabolism, we infused a peptide that enhanced autophagy (D-Tat-beclin1). This effectively lowered LPL levels at the coronary lumen by restoring autophagy in the genetic model of obesity. This decrease in cardiac luminal LPL was associated with a reduction in TG levels and recovery of cardiac function. Conclusion These results provide clear evidence of the critical role of modulating cardiac LPL activity through autophagy-mediated proteolytic clearance as a potential novel strategy to overcome obesity-related cardiomyopathy.
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Affiliation(s)
- Minae An
- Department of Pharmacology, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Dong-Ryeol Ryu
- Department of Internal Medicine, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Jang Won Park
- Department of Orthopedic surgery, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Ji Ha Choi
- Department of Pharmacology, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Eun-Mi Park
- Department of Pharmacology, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Kyung Eun Lee
- Department of Pharmacology, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Minna Woo
- Department of Medicine, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Minsuk Kim
- Department of Pharmacology, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
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Wolska A, Dunbar RL, Freeman LA, Ueda M, Amar MJ, Sviridov DO, Remaley AT. Apolipoprotein C-II: New findings related to genetics, biochemistry, and role in triglyceride metabolism. Atherosclerosis 2017; 267:49-60. [PMID: 29100061 DOI: 10.1016/j.atherosclerosis.2017.10.025] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/03/2017] [Accepted: 10/19/2017] [Indexed: 02/08/2023]
Abstract
Apolipoprotein C-II (apoC-II) is a small exchangeable apolipoprotein found on triglyceride-rich lipoproteins (TRL), such as chylomicrons (CM) and very low-density lipoproteins (VLDL), and on high-density lipoproteins (HDL), particularly during fasting. ApoC-II plays a critical role in TRL metabolism by acting as a cofactor of lipoprotein lipase (LPL), the main enzyme that hydrolyses plasma triglycerides (TG) on TRL. Here, we present an overview of the role of apoC-II in TG metabolism, emphasizing recent novel findings regarding its transcriptional regulation and biochemistry. We also review the 24 genetic mutations in the APOC2 gene reported to date that cause hypertriglyceridemia (HTG). Finally, we describe the clinical presentation of apoC-II deficiency and assess the current therapeutic approaches, as well as potential novel emerging therapies.
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Affiliation(s)
- Anna Wolska
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Richard L Dunbar
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA; ICON plc, North Wales, PA, USA; Cardiometabolic and Lipid Clinic, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA
| | - Lita A Freeman
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Masako Ueda
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Marcelo J Amar
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Denis O Sviridov
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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Yu JE, Han SY, Wolfson B, Zhou Q. The role of endothelial lipase in lipid metabolism, inflammation, and cancer. Histol Histopathol 2017; 33:1-10. [PMID: 28540715 DOI: 10.14670/hh-11-905] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Endothelial lipase (LIPG) plays a critical role in lipoprotein metabolism, cytokine expression, and the lipid composition of cells. Thus far, the extensive investigations of LIPG have focused on its mechanisms and involvement in metabolic syndromes such as atherosclerosis. However, recent developments have found that LIPG plays a role in cancer. This review summarizes the field of LIPG study. We focus on the role of LIPG in lipid metabolism and the inflammatory response, and highlight the recent insights in its involvement in tumor progression. Finally, we discuss potential therapeutic strategies for targeting LIPG in cancer, and the therapeutic potential of LIPG as a drug target.
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Affiliation(s)
- Justine E Yu
- Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, USA
| | - Shu-Yan Han
- Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, USA.,Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Integration of Chinese and Western Medicine, Peking University Cancer Hospital and Institute, Beijing, People's Republic of China
| | - Benjamin Wolfson
- Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, USA
| | - Qun Zhou
- Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, USA.
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Geldenhuys WJ, Lin L, Darvesh AS, Sadana P. Emerging strategies of targeting lipoprotein lipase for metabolic and cardiovascular diseases. Drug Discov Today 2016; 22:352-365. [PMID: 27771332 DOI: 10.1016/j.drudis.2016.10.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/17/2016] [Accepted: 10/12/2016] [Indexed: 12/12/2022]
Abstract
Although statins and other pharmacological approaches have improved the management of lipid abnormalities, there exists a need for newer treatment modalities especially for the management of hypertriglyceridemia. Lipoprotein lipase (LPL), by promoting hydrolytic cleavage of the triglyceride core of lipoproteins, is a crucial node in the management of plasma lipid levels. Although LPL expression and activity modulation is observed as a pleiotropic action of some the commonly used lipid lowering drugs, the deliberate development of drugs targeting LPL has not occurred yet. In this review, we present the biology of LPL, highlight the LPL modulation property of currently used drugs and review the novel emerging approaches to target LPL.
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Affiliation(s)
- Werner J Geldenhuys
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV 26505, USA
| | - Li Lin
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272, USA
| | - Altaf S Darvesh
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272, USA
| | - Prabodh Sadana
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272, USA.
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9
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Li Y, He PP, Zhang DW, Zheng XL, Cayabyab FS, Yin WD, Tang CK. Lipoprotein lipase: from gene to atherosclerosis. Atherosclerosis 2014; 237:597-608. [PMID: 25463094 DOI: 10.1016/j.atherosclerosis.2014.10.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 10/13/2014] [Accepted: 10/13/2014] [Indexed: 01/21/2023]
Abstract
Lipoprotein lipase (LPL) is a key enzyme in lipid metabolism and responsible for catalyzing lipolysis of triglycerides in lipoproteins. LPL is produced mainly in adipose tissue, skeletal and heart muscle, as well as in macrophage and other tissues. After synthesized, it is secreted and translocated to the vascular lumen. LPL expression and activity are regulated by a variety of factors, such as transcription factors, interactive proteins and nutritional state through complicated mechanisms. LPL with different distributions may exert distinct functions and have diverse roles in human health and disease with close association with atherosclerosis. It may pose a pro-atherogenic or an anti-atherogenic effect depending on its locations. In this review, we will discuss its gene, protein, synthesis, transportation and biological functions, and then focus on its regulation and relationship with atherosclerosis and potential underlying mechanisms. The goal of this review is to provide basic information and novel insight for further studies and therapeutic targets.
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Affiliation(s)
- Yuan Li
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Discovery, Life Science Research Center, University of South China, Hengyang, Hunan 421001, China
| | - Ping-Ping He
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Discovery, Life Science Research Center, University of South China, Hengyang, Hunan 421001, China; School of Nursing, University of South China, Hengyang, Hunan 421001, China
| | - Da-Wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Xi-Long Zheng
- Department of Biochemistry and Molecular Biology, The Libin Cardiovascular Institute of Alberta, The Cumming School of Medicine, The University of Calgary, Health Sciences Center, 3330 Hospital Dr NW, Calgary, Alberta T2N 4N1, Canada
| | - Fracisco S Cayabyab
- Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Wei-Dong Yin
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Discovery, Life Science Research Center, University of South China, Hengyang, Hunan 421001, China.
| | - Chao-Ke Tang
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Discovery, Life Science Research Center, University of South China, Hengyang, Hunan 421001, China.
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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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11
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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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12
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Benedito-Palos L, Ballester-Lozano G, Pérez-Sánchez J. Wide-gene expression analysis of lipid-relevant genes in nutritionally challenged gilthead sea bream (Sparus aurata). Gene 2014; 547:34-42. [DOI: 10.1016/j.gene.2014.05.073] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/26/2014] [Accepted: 05/31/2014] [Indexed: 12/22/2022]
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13
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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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14
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Type 1 hyperlipoproteinemia due to a novel deletion of exons 3 and 4 in the GPIHBP1 gene. Atherosclerosis 2014; 234:30-3. [DOI: 10.1016/j.atherosclerosis.2014.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/23/2014] [Accepted: 02/06/2014] [Indexed: 11/22/2022]
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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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Regulation of endothelial lipase and systemic HDL cholesterol levels by SREBPs and VEGF-A. Atherosclerosis 2012; 225:335-40. [DOI: 10.1016/j.atherosclerosis.2012.09.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 09/17/2012] [Accepted: 09/25/2012] [Indexed: 11/19/2022]
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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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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: 58] [Impact Index Per Article: 4.5] [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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