1
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Hu X, Matsumoto K, Jung RS, Weston TA, Heizer PJ, He C, Sandoval NP, Allan CM, Tu Y, Vinters HV, Liau LM, Ellison RM, Morales JE, Baufeld LJ, Bayley NA, He L, Betsholtz C, Beigneux AP, Nathanson DA, Gerhardt H, Young SG, Fong LG, Jiang H. GPIHBP1 expression in gliomas promotes utilization of lipoprotein-derived nutrients. eLife 2019; 8:e47178. [PMID: 31169500 PMCID: PMC6594755 DOI: 10.7554/elife.47178] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 06/05/2019] [Indexed: 12/25/2022] Open
Abstract
GPIHBP1, a GPI-anchored protein of capillary endothelial cells, binds lipoprotein lipase (LPL) within the subendothelial spaces and shuttles it to the capillary lumen. GPIHBP1-bound LPL is essential for the margination of triglyceride-rich lipoproteins (TRLs) along capillaries, allowing the lipolytic processing of TRLs to proceed. In peripheral tissues, the intravascular processing of TRLs by the GPIHBP1-LPL complex is crucial for the generation of lipid nutrients for adjacent parenchymal cells. GPIHBP1 is absent from the capillaries of the brain, which uses glucose for fuel; however, GPIHBP1 is expressed in the capillaries of mouse and human gliomas. Importantly, the GPIHBP1 in glioma capillaries captures locally produced LPL. We use NanoSIMS imaging to show that TRLs marginate along glioma capillaries and that there is uptake of TRL-derived lipid nutrients by surrounding glioma cells. Thus, GPIHBP1 expression in gliomas facilitates TRL processing and provides a source of lipid nutrients for glioma cells.
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Affiliation(s)
- Xuchen Hu
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Ken Matsumoto
- VIB-KU Leuven Center for Cancer Biology (CCB)LeuvenBelgium
| | - Rachel S Jung
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Thomas A Weston
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Patrick J Heizer
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Cuiwen He
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Norma P Sandoval
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Christopher M Allan
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Yiping Tu
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Harry V Vinters
- Department of Pathology and Laboratory Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Linda M Liau
- Department of Neurosurgery, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- Jonsson Comprehensive Cancer Center (JCCC), David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Rochelle M Ellison
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Jazmin E Morales
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Lynn J Baufeld
- Department of Molecular and Medical Pharmacology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- Ahmanson Translational Imaging Division, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Nicholas A Bayley
- Department of Molecular and Medical Pharmacology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- Ahmanson Translational Imaging Division, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Liqun He
- Department of Immunology, Genetics and Pathology, Rudbeck LaboratoryUppsala UniversityUppsalaSweden
| | - Christer Betsholtz
- Department of Immunology, Genetics and Pathology, Rudbeck LaboratoryUppsala UniversityUppsalaSweden
- Integrated Cardio Metabolic Centre (ICMC)Karolinska InstitutetHuddingeSweden
| | - Anne P Beigneux
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - David A Nathanson
- Department of Molecular and Medical Pharmacology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- Ahmanson Translational Imaging Division, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Holger Gerhardt
- VIB-KU Leuven Center for Cancer Biology (CCB)LeuvenBelgium
- Max Delbrück Center for Molecular MedicineBerlinGermany
| | - Stephen G Young
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- Department of Human Genetics, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Loren G Fong
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Haibo Jiang
- Department of Medicine, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- School of Molecular SciencesUniversity of Western AustraliaPerthAustralia
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2
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Abstract
Atherosclerosis, for which hyperlipidemia is a major risk factor, is the leading cause of morbidity and mortality in Western society, and new therapeutic strategies are highly warranted. Brown adipose tissue (BAT) is metabolically active in human adults. Although positron emission tomography-computed tomography using a glucose tracer is the golden standard to visualize and quantify the volume and activity of BAT, it has become clear that activated BAT combusts fatty acids rather than glucose. Here, we review the role of brown and beige adipocytes in lipoprotein metabolism and atherosclerosis, with evidence derived from both animal and human studies. On the basis of mainly data from animal models, we propose a model in which activated brown adipocytes use their intracellular triglyceride stores to generate fatty acids for combustion. BAT rapidly replenishes these stores by internalizing primarily lipoprotein triglyceride-derived fatty acids, generated by lipoprotein lipase-mediated hydrolysis of triglycerides, rather than by holoparticle uptake. As a consequence, BAT activation leads to the generation of lipoprotein remnants that are subsequently cleared via the liver provided that an intact apoE-low-density lipoprotein receptor pathway is present. Through these mechanisms, BAT activation reduces plasma triglyceride and cholesterol levels and attenuates diet-induced atherosclerosis development. Initial studies suggest that BAT activation in humans may also reduce triglyceride and cholesterol levels, but potential antiatherogenic effects should be assessed in future studies.
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Affiliation(s)
- Geerte Hoeke
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Sander Kooijman
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Mariëtte R Boon
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Patrick C N Rensen
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Jimmy F P Berbée
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
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3
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Impaired synaptic vesicle recycling contributes to presynaptic dysfunction in lipoprotein lipase-deficient mice. Neuroscience 2014; 280:275-81. [DOI: 10.1016/j.neuroscience.2014.07.080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/01/2014] [Accepted: 07/21/2014] [Indexed: 01/10/2023]
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4
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Gong H, Dong W, Rostad SW, Marcovina SM, Albers JJ, Brunzell JD, Vuletic S. Lipoprotein lipase (LPL) is associated with neurite pathology and its levels are markedly reduced in the dentate gyrus of Alzheimer's disease brains. J Histochem Cytochem 2013; 61:857-68. [PMID: 24004859 PMCID: PMC3840745 DOI: 10.1369/0022155413505601] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Lipoprotein lipase (LPL) is involved in regulation of fatty acid metabolism, and facilitates cellular uptake of lipoproteins, lipids and lipid-soluble vitamins. We evaluated LPL distribution in healthy and Alzheimer’s disease (AD) brain tissue and its relative levels in cerebrospinal fluid. LPL immunostaining is widely present in different neuronal subgroups, microglia, astrocytes and oligodendroglia throughout cerebrum, cerebellum and spinal cord. LPL immunoreactivity is also present in leptomeninges, small blood vessels, choroid plexus and ependymal cells, Schwann cells associated with cranial nerves, and in anterior and posterior pituitary. In vitro studies have shown presence of secreted LPL in conditioned media of human cortical neuronal cell line (HCN2) and neuroblastoma cells (SK-N-SH), but not in media of cultured primary human astrocytes. LPL was present in cytoplasmic and nuclear fractions of neuronal cells and astrocytes in vitro. LPL immunoreactivity strongly associates with AD-related pathology, staining diffuse plaques, dystrophic and swollen neurites, possible Hirano bodies and activated glial cells. We observed no staining associated with neurofibrillary tangles or granulovacuolar degeneration. Granule cells of the dentate gyrus and the associated synaptic network showed significantly reduced staining in AD compared to control tissue. LPL was also reduced in AD CSF samples relative to those in controls.
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Affiliation(s)
- Huilin Gong
- Northwest Lipid Metabolism and Diabetes Research Laboratories, Department of Medicine, School of Medicine, University of Washington, Seattle, WA (HG, WD, SMM, JJA, SV)
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5
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Adeyo O, Goulbourne CN, Bensadoun A, Beigneux AP, Fong LG, Young SG. Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 and the intravascular processing of triglyceride-rich lipoproteins. J Intern Med 2012; 272:528-40. [PMID: 23020258 PMCID: PMC3940157 DOI: 10.1111/joim.12003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lipoprotein lipase (LPL) is produced by parenchymal cells, mainly adipocytes and myocytes, but is involved in hydrolysing triglycerides in plasma lipoproteins at the capillary lumen. For decades, the mechanism by which LPL reaches its site of action in capillaries was unclear, but this mystery was recently solved. Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), a glycosylphosphatidylinositol-anchored protein of capillary endothelial cells, 'picks up' LPL from the interstitial spaces and shuttles it across endothelial cells to the capillary lumen. When GPIHBP1 is absent, LPL is mislocalized to the interstitial spaces, leading to severe hypertriglyceridaemia. Some cases of hypertriglyceridaemia in humans are caused by GPIHBP1 mutations that interfere with the ability of GPIHBP1 to bind to LPL, and some are caused by LPL mutations that impair the ability of LPL to bind to GPIHBP1. Here, we review recent progress in understanding the role of GPIHBP1 in health and disease and discuss some of the remaining unresolved issues regarding the processing of triglyceride-rich lipoproteins.
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Affiliation(s)
- O Adeyo
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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6
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Abstract
Lipoprotein lipase (LPL) is rate limiting in the provision of triglyceride-rich lipoprotein-derived lipids into tissues. LPL is also present in the brain, where its function has remained elusive. Recent evidence implicates a role of LPL in the brain in two processes: (a) the regulation of energy balance and body weight and (b) cognition. Mice with neuron-specific deletion of LPL have increases in food intake that lead to obesity, and then reductions in energy expenditure that further contribute to and sustain the phenotype. In other mice with LPL deficiency rescued from neonatal lethality by somatic gene transfer wherein LPL in the brain remains absent, altered cognition ensues. Taking into consideration data that associate LPL mutations with Alzheimer's disease, a role for LPL in learning and memory seems likely. Overall, the time is ripe for new insights into how LPL-mediated lipoprotein metabolism in the brain impacts CNS processes and systems biology.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, School of Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA.
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7
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Young SG, Davies BSJ, Voss CV, Gin P, Weinstein MM, Tontonoz P, Reue K, Bensadoun A, Fong LG, Beigneux AP. GPIHBP1, an endothelial cell transporter for lipoprotein lipase. J Lipid Res 2011; 52:1869-84. [PMID: 21844202 DOI: 10.1194/jlr.r018689] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Interest in lipolysis and the metabolism of triglyceride-rich lipoproteins was recently reignited by the discovery of severe hypertriglyceridemia (chylomicronemia) in glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1)-deficient mice. GPIHBP1 is expressed exclusively in capillary endothelial cells and binds lipoprotein lipase (LPL) avidly. These findings prompted speculation that GPIHBP1 serves as a binding site for LPL in the capillary lumen, creating "a platform for lipolysis." More recent studies have identified a second and more intriguing role for GPIHBP1-picking up LPL in the subendothelial spaces and transporting it across endothelial cells to the capillary lumen. Here, we review the studies that revealed that GPIHBP1 is the LPL transporter and discuss which amino acid sequences are required for GPIHBP1-LPL interactions. We also discuss the human genetics of LPL transport, focusing on cases of chylomicronemia caused by GPIHBP1 mutations that abolish GPIHBP1's ability to bind LPL, and LPL mutations that prevent LPL binding to GPIHBP1.
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Affiliation(s)
- Stephen G Young
- Department of Medicine, University of California, Los Angeles, CA 90095, USA.
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8
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Nishitsuji K, Hosono T, Uchimura K, Michikawa M. Lipoprotein lipase is a novel amyloid beta (Abeta)-binding protein that promotes glycosaminoglycan-dependent cellular uptake of Abeta in astrocytes. J Biol Chem 2010; 286:6393-401. [PMID: 21177248 DOI: 10.1074/jbc.m110.172106] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipoprotein lipase (LPL) is a member of a lipase family known to hydrolyze triglyceride molecules in plasma lipoprotein particles. LPL also plays a role in the binding of lipoprotein particles to cell-surface molecules, including sulfated glycosaminoglycans (GAGs). LPL is predominantly expressed in adipose and muscle but is also highly expressed in the brain where its specific roles are unknown. It has been shown that LPL is colocalized with senile plaques in Alzheimer disease (AD) brains, and its mutations are associated with the severity of AD pathophysiological features. In this study, we identified a novel function of LPL; that is, LPL binds to amyloid β protein (Aβ) and promotes cell-surface association and uptake of Aβ in mouse primary astrocytes. The internalized Aβ was degraded within 12 h, mainly in a lysosomal pathway. We also found that sulfated GAGs were involved in the LPL-mediated cellular uptake of Aβ. Apolipoprotein E was dispensable in the LPL-mediated uptake of Aβ. Our findings indicate that LPL is a novel Aβ-binding protein promoting cellular uptake and subsequent degradation of Aβ.
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Affiliation(s)
- Kazuchika Nishitsuji
- Section of Pathophysiology and Neurobiology, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8511, Japan
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9
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Westerterp M, Berbée JFP, Delsing DJM, Jong MC, Gijbels MJJ, Dahlmans VEH, Offerman EH, Romijn JA, Havekes LM, Rensen PCN. Apolipoprotein C-I binds free fatty acids and reduces their intracellular esterification. J Lipid Res 2007; 48:1353-61. [PMID: 17339654 DOI: 10.1194/jlr.m700024-jlr200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mice that overexpress human apolipoprotein C-I (apoC-I) homozygously (APOC1(+/+) mice) are protected against obesity and show cutaneous abnormalities. Although these effects can result from our previous observation that apoC-I inhibits FFA generation by LPL, we have also found that apoC-I impairs the uptake of a FFA analog in adipose tissue. In this study, we tested the hypothesis that apoC-I interferes with cellular FFA uptake independent of LPL activity. The cutaneous abnormalities of APOC1(+/+) mice were not affected after transplantation to wild-type mice, indicating that locally produced apoC-I prevents lipid entry into the skin. Subsequent in vitro studies with apoC-I-deficient versus wild-type macrophages revealed that apoC-I reduced the cell association and subsequent esterification of [(3)H]oleic acid by approximately 35% (P < 0.05). We speculated that apoC-I binds FFA extracellularly, thereby preventing cell association of FFA. We showed that apoC-I was indeed able to mediate the binding of oleic acid to otherwise protein-free VLDL-like emulsion particles involving electrostatic interaction. We conclude that apoC-I binds FFA in the circulation, thereby reducing the availability of FFA for uptake by cells. This mechanism can serve as an additional mechanism behind the resistance to obesity and the cutaneous abnormalities of APOC1(+/+) mice.
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Affiliation(s)
- Marit Westerterp
- Netherlands Organization for Applied Scientific Research-Quality of Life, Department of Biomedical Research, Gaubius Laboratory, Leiden, The Netherlands.
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10
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Victor NA, Wanderi EW, Gamboa J, Zhao X, Aronowski J, Deininger K, Lust WD, Landreth GE, Sundararajan S. Altered PPARgamma expression and activation after transient focal ischemia in rats. Eur J Neurosci 2007; 24:1653-63. [PMID: 17004929 DOI: 10.1111/j.1460-9568.2006.05037.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Stroke is a devastating disease with limited treatment options. Recently, we found that the peroxisome proliferator-activated receptor-gamma (PPARgamma) agonists troglitazone and pioglitazone reduce injury and inflammation in a rat model of transient cerebral ischemia. The mechanism of this protection is unclear, as these agents can act through PPAR-gamma activation or through PPAR-gamma-independent mechanisms. Therefore, we examined PPAR-gamma expression, DNA binding and transcriptional activity following stroke. In addition, we used a PPAR-gamma antagonist, T0070907, to determine the role of PPAR-gamma during ischemia. Using immunohistochemical techniques and real-time PCR, we found low levels of PPAR-gamma mRNA and PPAR-gamma immunoreactivity in nonischemic brain; however, PPAR-gamma expression dramatically increased in ischemic neurons, peaking 24 h following middle cerebral artery occlusion. Interestingly, we found that in both vehicle- and agonist-treated brains, DNA binding was reduced in the ischemic hemisphere relative to the contralateral hemisphere. Expression of a PPAR-gamma target gene, lipoprotein lipase, was also reduced in ischemic relative to nonischemic brain. Both DNA binding and lipoprotein lipase expression were increased by the addition of the PPAR-gamma agonist rosiglitazone. Finally, we found that rosiglitazone-mediated protection after stroke was reversed by the PPAR-gamma antagonist T0070907. Interestingly, infarction size was also increased by T0070907 in the absence of PPAR-gamma agonist, suggesting that endogenous PPAR-gamma ligands may mitigate the effects of cerebral ischemia.
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Affiliation(s)
- N A Victor
- Department of Neurology, Case Western Reserve University, 11100 Euclid Ave., Cleveland, Ohio 44106, USA
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11
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Paradis E, Clavel S, Julien P, Murthy MRV, de Bilbao F, Arsenijevic D, Giannakopoulos P, Vallet P, Richard D. Lipoprotein lipase and endothelial lipase expression in mouse brain: regional distribution and selective induction following kainic acid-induced lesion and focal cerebral ischemia. Neurobiol Dis 2004; 15:312-25. [PMID: 15006701 DOI: 10.1016/j.nbd.2003.09.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2003] [Revised: 09/02/2003] [Accepted: 09/26/2003] [Indexed: 01/21/2023] Open
Abstract
Lipoprotein and endothelial lipases are members of the triglyceride lipase gene family. These genes are expressed in the brain, where the encoded proteins are fulfilling functions that have yet to be elucidated. In this study, we examined the distribution of their respective mRNAs in the C57BL/6 mouse brain by in situ hybridization. In control mice, we observed widespread expression of lipoprotein lipase (LPL) mRNA mainly in pyramidal cells of the hippocampus (CA1, CA2 and CA3 areas), in the striatum and in several cortical areas. Endothelial lipase (EL) mRNA expression was restricted to CA3 pyramidal cells of the hippocampus, to ependymal cells in the ventral part of the third ventricle and to some cortical cell layers. To gain insight into the role played by lipases in the brain, neurodegeneration was induced by intraperitoneal injection of kainic acid (KA) or by occlusion of the middle cerebral artery (MCA). Upon injection of KA, a rapid increase in EL mRNA expression was observed in the piriform cortex, hippocampus, thalamus and neocortex. However, the levels of LPL mRNA were unaffected by KA injection. Remarkably, after focal cerebral ischemia, the expression of EL was unaffected whereas a dramatic increase in LPL expression was observed in neocortical areas of the lesioned side of the brain. These results show that LPL and EL transcripts are selectively upregulated in function of the type of brain injury. LPL and EL could thus fulfill a function in the pathophysiological response of the brain to injury.
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Affiliation(s)
- E Paradis
- Department of Medical Biology, Faculty of Medicine, Laval University, Ste-Foy (PQ), Canada
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12
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Paradis E, Clement S, Julien P, Ven Murthy MR. Lipoprotein lipase affects the survival and differentiation of neural cells exposed to very low density lipoprotein. J Biol Chem 2003; 278:9698-705. [PMID: 12501246 DOI: 10.1074/jbc.m208452200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipoprotein lipase (LPL) is a key enzyme involved in the metabolism of lipoproteins, providing tissues like adipose tissue or skeletal muscle with fatty acids. LPL is also expressed in the brain, fulfilling yet unknown functions. Using a neuroblastoma cell line transfected with a NEO- or a LPL-expression vector, we have developed a model to study the function of LPL in neurons exposed to native or copper-oxidized lipoproteins. The addition to the culture media of VLDL with 10 microm copper sulfate led to a significant reduction in the viability of NEO transfectants whereas LPL-transfectants were protected from this injury. In the presence of VLDL and CuSO(4), LPL transfectants were even able to display significant neurite extension. This neuritogenic effect was also observed in LPL transfectants exposed to native lipoproteins. However, addition of VLDL particles oxidized with CuSO(4) prior to their addition to the culture media resulted in neurotoxic effects on LPL transfectants. These findings suggest that the presence of LPL in cultured neuronal cells modulates the physiological response of neurons following exposure to native or oxidized lipoproteins. LPL could thus play a key role in the differentiation of Neuro-2A cells and in the pathophysiological effects of oxidative stress in several neurodegenerative disorders.
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Affiliation(s)
- Eric Paradis
- Department of Medical Biology, Faculty of Medicine and Lipid Research Centre, Laval University Medical Research Centre, Laval University, Ste-Foy, Quebec G1K 7P4, Canada
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13
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Preiss-Landl K, Zimmermann R, Hämmerle G, Zechner R. Lipoprotein lipase: the regulation of tissue specific expression and its role in lipid and energy metabolism. Curr Opin Lipidol 2002; 13:471-81. [PMID: 12352010 DOI: 10.1097/00041433-200210000-00002] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
PURPOSE OF REVIEW The aim of this review is to summarize and discuss recent advances in the understanding of the physiological role of lipoprotein lipase in lipid and energy metabolism. RECENT FINDINGS Studies on the transcriptional and the posttranscriptional level of lipoprotein lipase expression have provided new insights into the complex mechanisms that are involved in the regulation of the enzyme. Additionally a large body of evidence from both human studies and animal models suggests that the level of lipoprotein lipase expression in a given tissue is the rate limiting process for the uptake of triglyceride derived fatty acids. Imbalances in the partitioning of fatty acids among peripheral tissues have major metabolic consequences. For example, in mice both decreased lipoprotein lipase activities in adipose tissue and increased activity in muscle are associated with resistance to obesity; lack of lipoprotein lipase activity in macrophages is correlated with a decreased susceptibility to develop atherosclerotic lesions and overexpression of the enzyme in muscle is associated with increased blood glucose levels and insulin resistance. SUMMARY Considering the central role of lipoprotein lipase in energy metabolism it is a reasonable goal to discover and develop new drugs that affect the tissue specific expression pattern of the enzyme.
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Affiliation(s)
- Karina Preiss-Landl
- Institute of Molecular Bioloogy, Biochemistry and Microbiology, Karl-Frasnzens-University, Graz, Heinrichstrasse 31a, A-8010 Graz, Austria
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14
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Merkel M, Heeren J, Dudeck W, Rinninger F, Radner H, Breslow JL, Goldberg IJ, Zechner R, Greten H. Inactive lipoprotein lipase (LPL) alone increases selective cholesterol ester uptake in vivo, whereas in the presence of active LPL it also increases triglyceride hydrolysis and whole particle lipoprotein uptake. J Biol Chem 2002; 277:7405-11. [PMID: 11751882 DOI: 10.1074/jbc.m107914200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We have previously shown that transgenic expression of catalytically inactive lipoprotein lipase (LPL) in muscle (Mck-N-LPL) enhances triglyceride hydrolysis as well as whole particle lipoprotein and selective cholesterol ester uptake. In the current study, we have examined whether these functions can be performed by inactive LPL alone or require the presence of active LPL expressed in the same tissue. To study inactive LPL in the presence of active LPL in the same tissue, the Mck-N-LPL transgene was bred onto the heterozygous LPL-deficient (LPL1) background. At 18 h of age, Mck-N-LPL reduced triglycerides by 35% and markedly increased muscle lipid droplets. In adult mice, it reduced triglycerides by 40% and increased lipoprotein particle uptake into muscle by 60% and cholesterol ester uptake by 110%. To study inactive LPL alone, the Mck-N-LPL transgene was bred onto the LPL-deficient (LPL0) background. These mice die at approximately 24 h of age. At 18 h of age, in the absence of active LPL, inactive LPL expression did not diminish triglycerides nor did it result in the accumulation of muscle lipid droplets. To study inactive LPL in the absence of active LPL in the same tissue in adult animals, the Mck-N-LPL transgene was bred onto mice that only expressed active LPL in the heart (LPL0/He-LPL). In this case, Mck-N-LPL did not reduce triglycerides or increase the uptake of lipoprotein particles but did increase muscle uptake of chylomicron and very low density lipoprotein cholesterol ester by 40%. Thus, in the presence of active LPL in the same tissue, inactive LPL augments triglyceride hydrolysis and increases whole particle triglyceride-rich lipoprotein and selective cholesterol ester uptake. In the absence of active LPL in the same tissue, inactive LPL only mediates selective cholesterol ester uptake.
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Affiliation(s)
- Martin Merkel
- Department of Medicine, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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15
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Tiebel O, Oka K, Robinson K, Sullivan M, Martinez J, Nakamuta M, Ishimura-Oka K, Chan L. Mouse very low-density lipoprotein receptor (VLDLR): gene structure, tissue-specific expression and dietary and developmental regulation. Atherosclerosis 1999; 145:239-51. [PMID: 10488949 DOI: 10.1016/s0021-9150(99)00068-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The very low density lipoprotein receptor (VLDLR) is a multifunctional apolipoprotein (apo) E receptor that shares a common structural feature as well as some ligand specificity to apo E with members of the low density lipoprotein receptor gene family. We have isolated and characterized the mouse VLDLR gene. The mouse VLDLR gene contains 19 exons spanning approximately 50 kb. The exon-intron organization of the gene is completely conserved between mouse and human. Since the 5'-flanking region of the mouse VLDLR gene contains two copies of a sterol regulatory element-1 like sequence (SRE-1), we next studied regulation of the VLDLR mRNA expression in heart, skeletal muscle and adipose tissue in C57BL/6, LDLR-/-, apo E-/- and LDLR-/-apo E-/- mice fed normal chow or atherogenic diet. The VLDLR mRNA expression was down-regulated 3-fold by feeding atherogenic diet in heart and skeletal muscle only in LDLR-/- mice. In contrast, VLDLR mRNA expression was up-regulated by atherogenic diet in adipose tissue in all animal models except double knockout mice. These results suggest that SRE-1 may be functional and VLDLR plays a role in cholesterol homeostasis in heart and skeletal muscle when LDLR is absent and that apo E is required for this modulation. Developmental regulation of the VLDLR mRNA expression was also tissue-specific. VLDLR mRNA expression in heart displayed significant up and down regulation during development. Maximal level was detected on post-natal day 3. However, the VLDLR mRNA levels in skeletal muscle remained relatively constant except a slight dip on post-natal day 7. In kidney and brain, VLDLR mRNA also peaked on post-natal day 3 but remained relatively constant thereafter. In liver, VLDLR mRNA expression was very low; it was barely detectable at day 19 of gestation and was decreased further thereafter. In adipose tissue, the VLDLR mRNA level showed an increase on post-natal day 13, went down again during weaning and then continued to increase afterwards. This developmental pattern as well as dietary regulation in adipose tissue supports the notion that VLDLR plays a role in lipid accumulation in this tissue. Although the primary role of VLDLR in heart, muscle and adipose tissue is likely in lipid metabolism, developmental pattern of this receptor in other tissues suggests that VLDLR has functions that are unrelated to lipid metabolism.
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MESH Headings
- Adipose Tissue/growth & development
- Adipose Tissue/metabolism
- Animals
- Base Sequence
- Blotting, Northern
- Diet, Atherogenic
- Down-Regulation
- Female
- Gene Expression Regulation, Developmental
- Heart/growth & development
- Lipoproteins, VLDL/biosynthesis
- Lipoproteins, VLDL/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Sequence Data
- Muscle Development
- Muscle, Skeletal/growth & development
- Muscle, Skeletal/metabolism
- Myocardium/metabolism
- Polymerase Chain Reaction
- Pregnancy
- RNA Probes/chemistry
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptors, LDL/biosynthesis
- Receptors, LDL/genetics
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Affiliation(s)
- O Tiebel
- Department of Cell Biology and Medicine, Baylor College of Medicine, Houston, TX 77030, USA
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16
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Bessesen DH, Richards CL, Etienne J, Goers JW, Eckel RH. Spinal cord of the rat contains more lipoprotein lipase than other brain regions. J Lipid Res 1993. [DOI: 10.1016/s0022-2275(20)40750-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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17
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Affiliation(s)
- K E Suckling
- SmithKline Beecham Pharmaceuticals, Welwyn, Herts, U.K
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