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Manikowski D, Steffes G, Froese J, Exner S, Ehring K, Gude F, Di Iorio D, Wegner SV, Grobe K. Drosophila hedgehog signaling range and robustness depend on direct and sustained heparan sulfate interactions. Front Mol Biosci 2023; 10:1130064. [PMID: 36911531 PMCID: PMC9992881 DOI: 10.3389/fmolb.2023.1130064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
Morphogens determine cellular differentiation in many developing tissues in a concentration dependent manner. As a central model for gradient formation during animal development, Hedgehog (Hh) morphogens spread away from their source to direct growth and pattern formation in the Drosophila wing disc. Although heparan sulfate (HS) expression in the disc is essential for this process, it is not known whether HS regulates Hh signaling and spread in a direct or in an indirect manner. To answer this question, we systematically screened two composite Hh binding areas for HS in vitro and expressed mutated proteins in the Drosophila wing disc. We found that selectively impaired HS binding of the second site reduced Hh signaling close to the source and caused striking wing mispatterning phenotypes more distant from the source. These observations suggest that HS constrains Hh to the wing disc epithelium in a direct manner, and that interfering with this constriction converts Hh into freely diffusing forms with altered signaling ranges and impaired gradient robustness.
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Affiliation(s)
- Dominique Manikowski
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Georg Steffes
- Institute of Neuro- and Behavioral Biology, University of Münster, Münster, Germany
| | - Jurij Froese
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Sebastian Exner
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Kristina Ehring
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Fabian Gude
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Daniele Di Iorio
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Seraphine V Wegner
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
| | - Kay Grobe
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
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2
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Leskelä J, Toppila I, Härma MA, Palviainen T, Salminen A, Sandholm N, Pietiäinen M, Kopra E, Pais de Barros JP, Lassenius MI, Kumar A, Harjutsalo V, Roslund K, Forsblom C, Loukola A, Havulinna AS, Lagrost L, Salomaa V, Groop PH, Perola M, Kaprio J, Lehto M, Pussinen PJ. Genetic Profile of Endotoxemia Reveals an Association With Thromboembolism and Stroke. J Am Heart Assoc 2021; 10:e022482. [PMID: 34668383 PMCID: PMC8751832 DOI: 10.1161/jaha.121.022482] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Translocation of lipopolysaccharide from gram-negative bacteria into the systemic circulation results in endotoxemia. In addition to acute infections, endotoxemia is detected in cardiometabolic disorders, such as cardiovascular diseases and obesity. Methods and Results We performed a genome-wide association study of serum lipopolysaccharide activity in 11 296 individuals from 6 different Finnish study cohorts. Endotoxemia was measured by limulus amebocyte lysate assay in the whole population and by 2 other techniques (Endolisa and high-performance liquid chromatography/tandem mass spectrometry) in subpopulations. The associations of the composed genetic risk score of endotoxemia and thrombosis-related clinical end points for 195 170 participants were analyzed in FinnGen. Lipopolysaccharide activity had a genome-wide significant association with 741 single-nucleotide polymorphisms in 5 independent loci, which were mainly located at genes affecting the contact activation of the coagulation cascade and lipoprotein metabolism and explained 1.5% to 9.2% of the variability in lipopolysaccharide activity levels. The closest genes included KNG1, KLKB1, F12, SLC34A1, YPEL4, CLP1, ZDHHC5, SERPING1, CBX5, and LIPC. The genetic risk score of endotoxemia was associated with deep vein thrombosis, pulmonary embolism, pulmonary heart disease, and venous thromboembolism. Conclusions The biological activity of lipopolysaccharide in the circulation (ie, endotoxemia) has a small but highly significant genetic component. Endotoxemia is associated with genetic variation in the contact activation pathway, vasoactivity, and lipoprotein metabolism, which play important roles in host defense, lipopolysaccharide neutralization, and thrombosis, and thereby thromboembolism and stroke.
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Affiliation(s)
- Jaakko Leskelä
- Oral and Maxillofacial Diseases University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Iiro Toppila
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Mari-Anne Härma
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Teemu Palviainen
- Institute for Molecular Medicine Finland University of Helsinki Finland
| | - Aino Salminen
- Oral and Maxillofacial Diseases University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Niina Sandholm
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Milla Pietiäinen
- Oral and Maxillofacial Diseases University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Elisa Kopra
- Oral and Maxillofacial Diseases University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Jean-Paul Pais de Barros
- INSERM UMR1231 Dijon France.,Lipidomic Analytical Platform, University Bourgogne Franche-Comté Dijon France.,LipSTIC LabEx Dijon France
| | | | - Mariann I Lassenius
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Anmol Kumar
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Valma Harjutsalo
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Kajsa Roslund
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Carol Forsblom
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Anu Loukola
- Institute for Molecular Medicine Finland University of Helsinki Finland.,Department of Public Health Solutions Finnish Institute for Health and Welfare Helsinki Finland.,Department of Public Health University of Helsinki Finland
| | - Aki S Havulinna
- Institute for Molecular Medicine Finland University of Helsinki Finland.,Department of Public Health Solutions Finnish Institute for Health and Welfare Helsinki Finland
| | - Laurent Lagrost
- INSERM UMR1231 Dijon France.,LipSTIC LabEx Dijon France.,University Bourgogne Franche-Comté Dijon France.,University Hospital, Hôpital du Bocage Dijon France
| | - Veikko Salomaa
- Department of Public Health Solutions Finnish Institute for Health and Welfare Helsinki Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland.,Department of Diabetes Central Clinical School Monash University Melbourne Victoria Australia
| | - Markus Perola
- Genomics and Biomarkers Unit Department of Health Finnish Institute for Health and Welfare Helsinki Finland
| | - Jaakko Kaprio
- Institute for Molecular Medicine Finland University of Helsinki Finland.,Department of Public Health University of Helsinki Finland
| | - Markku Lehto
- Folkhälsan Institute of GeneticsFolkhälsan Research Center Helsinki Finland.,Abdominal Center Nephrology University of Helsinki and Helsinki University Hospital Helsinki Finland.,Diabetes and Obesity Research Program Research Programs Unit University of Helsinki Finland
| | - Pirkko J Pussinen
- Oral and Maxillofacial Diseases University of Helsinki and Helsinki University Hospital Helsinki Finland
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3
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Akazawa T, Ogawa M, Hayakawa S. Migration of chicken egg-white protein ovalbumin-related protein X and its alteration in heparin-binding affinity during embryogenesis of fertilized egg. Poult Sci 2019; 98:5100-5108. [DOI: 10.3382/ps/pez335] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 05/26/2019] [Indexed: 12/13/2022] Open
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4
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Chen J, Kaiyala KJ, Lam J, Agrawal N, Nguyen L, Ogimoto K, Spencer D, Morton GJ, Schwartz MW, Dichek HL. In vivo structure-function studies of human hepatic lipase: the catalytic function rescues the lean phenotype of HL-deficient (hl-/-) mice. Physiol Rep 2015; 3:e12365. [PMID: 25862097 PMCID: PMC4425970 DOI: 10.14814/phy2.12365] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 02/23/2015] [Accepted: 02/28/2015] [Indexed: 11/30/2022] Open
Abstract
The lean body weight phenotype of hepatic lipase (HL)-deficient mice (hl(-/-)) suggests that HL is required for normal weight gain, but the underlying mechanisms are unknown. HL plays a unique role in lipoprotein metabolism performing bridging as well as catalytic functions, either of which could participate in energy homeostasis. To determine if both the catalytic and bridging functions or the catalytic function alone are required for the effect of HL on body weight, we studied (hl(-/-)) mice that transgenically express physiologic levels of human (h)HL (with catalytic and bridging functions) or a catalytically-inactive (ci)HL variant (with bridging function only) in which the catalytic Serine 145 was mutated to Alanine. As expected, HL activity in postheparin plasma was restored to physiologic levels only in hHL-transgenic mice (hl(-/-)hHL). During high-fat diet feeding, hHL-transgenic mice exhibited increased body weight gain and body adiposity relative to hl(-/-)ciHL mice. A similar, albeit less robust effect was observed in female hHL-transgenic relative to hl(-/-)ciHL mice. To delineate the basis for this effect, we determined cumulative food intake and measured energy expenditure using calorimetry. Interestingly, in both genders, food intake was 5-10% higher in hl(-/-)hHL mice relative to hl(-/-)ciHL controls. Similarly, energy expenditure was ~10% lower in HL-transgenic mice after adjusting for differences in total body weight. Our results demonstrate that (1) the catalytic function of HL is required to rescue the lean body weight phenotype of hl(-/-) mice; (2) this effect involves complementary changes in both sides of the energy balance equation; and (3) the bridging function alone is insufficient to rescue the lean phenotype of hl(-/-)ciHL mice.
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Affiliation(s)
- Jeffrey Chen
- Department of Pediatrics, University of Washington, Seattle, Washington
| | - Karl J Kaiyala
- Department of Dental Public Health Sciences, School of Dentistry University of Washington, Seattle, Washington
| | - Jennifer Lam
- Department of Pediatrics, University of Washington, Seattle, Washington
| | - Nalini Agrawal
- Department of Pediatrics, University of Washington, Seattle, Washington
| | - Lisa Nguyen
- Department of Pediatrics, University of Washington, Seattle, Washington
| | - Kayoko Ogimoto
- Department of Medicine, Diabetes and Obesity Center of Excellence, University of Washington, Seattle, Washington
| | - Dean Spencer
- Department of Pediatrics, University of Washington, Seattle, Washington
| | - Gregory J Morton
- Department of Medicine, Diabetes and Obesity Center of Excellence, University of Washington, Seattle, Washington
| | - Michael W Schwartz
- Department of Medicine, Diabetes and Obesity Center of Excellence, University of Washington, Seattle, Washington
| | - Helén L Dichek
- Department of Pediatrics, University of Washington, Seattle, Washington
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Gonzales JC, Gordts PLSM, Foley EM, Esko JD. Apolipoproteins E and AV mediate lipoprotein clearance by hepatic proteoglycans. J Clin Invest 2013; 123:2742-51. [PMID: 23676495 DOI: 10.1172/jci67398] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/14/2013] [Indexed: 11/17/2022] Open
Abstract
The heparan sulfate proteoglycan (HSPG) syndecan-1 (SDC1) acts as a major receptor for triglyceride-rich lipoprotein (TRL) clearance in the liver. We sought to identify the relevant apolipoproteins on TRLs that mediate binding to SDC1 and determine their clinical relevance. Evidence supporting ApoE as a major determinant arose from its enrichment in TRLs from mice defective in hepatic heparan sulfate (Ndst1f/fAlbCre⁺ mice), decreased binding of ApoE-deficient TRLs to HSPGs on human hepatoma cells, and decreased clearance of ApoE-deficient [³H]TRLs in vivo. Evidence for a second ligand was suggested by the faster clearance of ApoE-deficient TRLs after injection into WT Ndst1f/fAlbCre⁻ versus mutant Ndst1f/fAlbCre⁺ mice and elevated fasting and postprandial plasma triglycerides in compound Apoe⁻/⁻Ndst1f/fAlbCre⁺ mice compared with either single mutant. ApoAV emerged as a candidate based on 6-fold enrichment of ApoAV in TRLs accumulating in Ndst1f/fAlbCre⁺ mice, decreased binding of TRLs to proteoglycans after depletion of ApoAV or addition of anti-ApoAV mAb, and decreased heparan sulfate-dependent binding of ApoAV-deficient particles to hepatocytes. Importantly, disruption of hepatic heparan sulfate-mediated clearance increased atherosclerosis. We conclude that clearance of TRLs by hepatic HSPGs is atheroprotective and mediated by multivalent binding to ApoE and ApoAV.
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Affiliation(s)
- Jon C Gonzales
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, UCSD, La Jolla, California 92093-0687, USA
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6
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Iizuka Y, Ueda S, Hanada T, Tani W, Adachi H, Haga R, Yamaguchi M, Kurotani W, Sekiguchi M, Kang D, Sakasegawa SI. 1,2-Dioleoylglycerol method for pancreatic lipase catalytic activity in serum. Clin Chem Lab Med 2011; 50:475-81. [PMID: 22126376 DOI: 10.1515/cclm.2011.811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 11/11/2011] [Indexed: 11/15/2022]
Abstract
BACKGROUND There is a need for a pancreatic lipase (LIP) reference assay to provide an accurate base to which routine methods can be traceable. METHODS This study developed a novel LIP assay method in which 1,2-dioleoylglycerol (DODG) is the substrate and LIP activity is measured in a coupled enzymatic reaction from the increase in absorbance at 340 nm with production of NADPH. RESULTS With this method, LIP activity was linear up to 440 U/L (8-times expected upper limit of physiological concentration). When assayed manually, the between-laboratory variation for six samples surveyed at five laboratories was 3.80-26.4% (CV) for samples containing about 20-290 U/L LIP activity; when assayed using an automated analyzer, the range was 1.86-4.86% (four laboratories). Interference by >5 mmol/L glycerol and low specificity with post-heparin samples were noted, but in practice these are avoidable. Precision analyzed by automated assay of 49 samples twice in random order produced a covariance of 2.27 U/L, which is comparable to routine methods, and good correlations were obtained with five routine methods. CONCLUSIONS Although further studies are required, the DODG method may be likely applicable as one candidate reference method.
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7
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Deletion of the basement membrane heparan sulfate proteoglycan type XVIII collagen causes hypertriglyceridemia in mice and humans. PLoS One 2010; 5:e13919. [PMID: 21085708 PMCID: PMC2978080 DOI: 10.1371/journal.pone.0013919] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 10/15/2010] [Indexed: 01/15/2023] Open
Abstract
Background Lipoprotein lipase (Lpl) acts on triglyceride-rich lipoproteins in the peripheral circulation, liberating free fatty acids for energy metabolism or storage. This essential enzyme is synthesized in parenchymal cells of adipose tissue, heart, and skeletal muscle and migrates to the luminal side of the vascular endothelium where it acts upon circulating lipoproteins. Prior studies suggested that Lpl is immobilized by way of heparan sulfate proteoglycans on the endothelium, but genetically altering endothelial cell heparan sulfate had no effect on Lpl localization or lipolysis. The objective of this study was to determine if extracellular matrix proteoglycans affect Lpl distribution and triglyceride metabolism. Methods and Findings We examined mutant mice defective in collagen XVIII (Col18), a heparan sulfate proteoglycan present in vascular basement membranes. Loss of Col18 reduces plasma levels of Lpl enzyme and activity, which results in mild fasting hypertriglyceridemia and diet-induced hyperchylomicronemia. Humans with Knobloch Syndrome caused by a null mutation in the vascular form of Col18 also present lower than normal plasma Lpl mass and activity and exhibit fasting hypertriglyceridemia. Conclusions This is the first report demonstrating that Lpl presentation on the lumenal side of the endothelium depends on a basement membrane proteoglycan and demonstrates a previously unrecognized phenotype in patients lacking Col18.
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8
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Foley EM, Esko JD. Hepatic heparan sulfate proteoglycans and endocytic clearance of triglyceride-rich lipoproteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 93:213-33. [PMID: 20807647 DOI: 10.1016/s1877-1173(10)93010-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hypertriglyceridemia, characterized by the accumulation of triglyceride-rich lipoproteins in the blood, affects 10-20% of the population in western countries and increases the risk of atherosclerosis, coronary artery disease, and pancreatitis. The etiology of hypertriglyceridemia is complex, and much interest exists in identifying and characterizing the biological and environmental factors that affect the synthesis and turnover of plasma triglycerides. Genetic studies in mice have recently identified that heparan sulfate proteoglycans are a class of receptors that mediate the clearance of triglyceride-rich lipoproteins in the liver. Heparan sulfate proteoglycans are expressed by endothelial cells that line the hepatic sinusoids and the underlying hepatocytes, and are present in the perisinusoidal space (space of Disse). This chapter discusses the dependence of lipoprotein binding on heparan sulfate structure and the identification of hepatocyte syndecan-1 as the primary proteoglycan that mediates triglyceride-rich lipoprotein clearance.
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Affiliation(s)
- Erin M Foley
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, USA
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Stanford KI, Wang L, Castagnola J, Song D, Bishop JR, Brown JR, Lawrence R, Bai X, Habuchi H, Tanaka M, Cardoso WV, Kimata K, Esko JD. Heparan sulfate 2-O-sulfotransferase is required for triglyceride-rich lipoprotein clearance. J Biol Chem 2009; 285:286-94. [PMID: 19889634 DOI: 10.1074/jbc.m109.063701] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hepatic clearance of triglyceride-rich lipoproteins depends on heparan sulfate and low density lipoprotein receptors expressed on the basal membrane of hepatocytes. Binding and uptake of the lipoproteins by way of heparan sulfate depends on the degree of sulfation of the chains based on accumulation of plasma triglycerides and delayed clearance of triglyceride-rich lipoproteins in mice bearing a hepatocyte-specific alteration of N-acetylglucosamine (GlcNAc) N-deacetylase-N-sulfotransferase 1 (Ndst1) (MacArthur, J. M., Bishop, J. R., Stanford, K. I., Wang, L., Bensadoun, A., Witztum, J. L., and Esko, J. D. (2007) J. Clin. Invest. 117, 153-164). Inactivation of Ndst1 led to decreased overall sulfation of heparan sulfate due to coupling of uronyl 2-O-sulfation and glucosaminyl 6-O-sulfation to initial N-deacetylation and N-sulfation of GlcNAc residues. To determine whether lipoprotein clearance depends on 2-O-and 6-O-sulfation, we evaluated plasma triglyceride levels in mice containing loxP-flanked conditional alleles of uronyl 2-O-sulfotransferase (Hs2st(f/f)) and glucosaminyl 6-O-sulfotransferase-1 (Hs6st1(f/f)) and the bacterial Cre recombinase expressed in hepatocytes from the rat albumin (Alb) promoter. We show that Hs2st(f/f)AlbCre(+) mice accumulated plasma triglycerides and exhibited delayed clearance of intestinally derived chylomicrons and injected human very low density lipoproteins to the same extent as observed in Ndst1(f/f)AlbCre(+) mice. In contrast, Hs6st1(f/f)AlbCre(+) mice did not exhibit any changes in plasma triglycerides. Chemically modified heparins lacking N-sulfate and 2-O-sulfate groups did not block very low density lipoprotein binding and uptake in isolated hepatocytes, whereas heparin lacking 6-O-sulfate groups was as active as unaltered heparin. Our findings show that plasma lipoprotein clearance depends on specific subclasses of sulfate groups and not on overall charge of the chains.
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Affiliation(s)
- Kristin I Stanford
- Department of Cellular and Molecular Medicine and the Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California 92093-0687, USA
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10
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MacArthur JM, Bishop JR, Stanford KI, Wang L, Bensadoun A, Witztum JL, Esko JD. Liver heparan sulfate proteoglycans mediate clearance of triglyceride-rich lipoproteins independently of LDL receptor family members. J Clin Invest 2007; 117:153-64. [PMID: 17200715 PMCID: PMC1716206 DOI: 10.1172/jci29154] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Accepted: 10/03/2006] [Indexed: 12/17/2022] Open
Abstract
We examined the role of hepatic heparan sulfate in triglyceride-rich lipoprotein metabolism by inactivating the biosynthetic gene GlcNAc N-deacetylase/N-sulfotransferase 1 (Ndst1) in hepatocytes using the Cre-loxP system, which resulted in an approximately 50% reduction in sulfation of liver heparan sulfate. Mice were viable and healthy, but they accumulated triglyceride-rich lipoprotein particles containing apoB-100, apoB-48, apoE, and apoCI-IV. Compounding the mutation with LDL receptor deficiency caused enhanced accumulation of both cholesterol- and triglyceride-rich particles compared with mice lacking only LDL receptors, suggesting that heparan sulfate participates in the clearance of cholesterol-rich lipoproteins as well. Mutant mice synthesized VLDL normally but showed reduced plasma clearance of human VLDL and a corresponding reduction in hepatic VLDL uptake. Retinyl ester excursion studies revealed that clearance of intestinally derived lipoproteins also depended on hepatocyte heparan sulfate. These findings show that under normal physiological conditions, hepatic heparan sulfate proteoglycans play a crucial role in the clearance of both intestinally derived and hepatic lipoprotein particles.
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Affiliation(s)
- Jennifer M. MacArthur
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Joseph R. Bishop
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Kristin I. Stanford
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Lianchun Wang
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - André Bensadoun
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Joseph L. Witztum
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Jeffrey D. Esko
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
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12
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Fasciano S, Hutchins B, Handy I, Patel RC. Identification of the heparin-binding domains of the interferon-induced protein kinase, PKR. FEBS J 2005; 272:1425-39. [PMID: 15752359 PMCID: PMC3969814 DOI: 10.1111/j.1742-4658.2005.04575.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PKR is an interferon-induced serine-threonine protein kinase that plays an important role in the mediation of the antiviral and antiproliferative actions of interferons. PKR is present at low basal levels in cells and its expression is induced at the transcriptional level by interferons. PKR's kinase activity stays latent until it binds to its activator. In the case of virally infected cells, double-stranded (ds) RNA serves as PKR's activator. The dsRNA binds to PKR via two copies of an evolutionarily conserved motif, thus inducing a conformational change, unmasking the ATP-binding site and leading to autophosphorylation of PKR. Activated PKR then phosphorylates the alpha-subunit of the protein synthesis initiation factor 2 (eIF2alpha) thereby inducing a general block in the initiation of protein synthesis. In addition to dsRNA, polyanionic agents such as heparin can also activate PKR. In contrast to dsRNA-induced activation of PKR, heparin-dependent PKR activation has so far remained uncharacterized. In order to understand the mechanism of heparin-induced PKR activation, we have mapped the heparin-binding domains of PKR. Our results indicate that PKR has two heparin-binding domains that are nonoverlapping with its dsRNA-binding domains. Although both these domains can function independently of each other, they function cooperatively when present together. Point mutations created within these domains rendered PKR defective in heparin-binding, thereby confirming their essential role. In addition, these mutants were defective in kinase activity as determined by both in vitro and in vivo assays.
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Affiliation(s)
- Stephen Fasciano
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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13
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Brown RJ, Schultz JR, Ko KWS, Hill JS, Ramsamy TA, White AL, Sparks DL, Yao Z. The amino acid sequences of the carboxyl termini of human and mouse hepatic lipase influence cell surface association. J Lipid Res 2003; 44:1306-14. [PMID: 12700335 DOI: 10.1194/jlr.m200374-jlr200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human hepatic lipase (hHL) mainly exists cell surface bound, whereas mouse HL (mHL) circulates in the blood stream. Studies have suggested that the carboxyl terminus of HL mediates cell surface binding. We prepared recombinant hHL, mHL, and chimeric proteins (hHLmt and mHLht) in which the carboxyl terminal 70 amino acids of hHL were exchanged with the corresponding sequence from mHL. The hHL, mHL, and hHLmt proteins were catalytically active using triolein and tributyrin as substrates. In transfected cells, the majority of hHLs bound to the cell surface, with only 4% of total extracellular hHL released into heparin-free media, whereas under the same conditions, 61% of total extracellular mHLs were released. Like mHL, hHLmt showed decreased cell surface binding, with 68% of total extracellular hHLmt released. To determine the precise amino acid residues involved in cell surface binding, we prepared a truncated hHL mutant (hHL471) by deleting the carboxyl terminal five residues (KRKIR). The hHL471 also retained hydrolytic activity with triolein and tributyrin, and showed decreased cell surface binding, with 40% of total extracellular protein released into the heparin-free media. These data suggest that the determinants of cell surface binding exist within the carboxyl terminal 70 amino acids of hHL, of which the last five residues play an important role.
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Affiliation(s)
- Robert J Brown
- Lipoprotein and Atherosclerosis Research Group, University of Ottawa, Ottawa, Ontario, Canada
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Aubert E, Sbarra V, Le Petit-Thévenin J, Valette A, Lombardo D. Site-directed mutagenesis of the basic N-terminal cluster of pancreatic bile salt-dependent lipase. Functional significance. J Biol Chem 2002; 277:34987-96. [PMID: 12110666 DOI: 10.1074/jbc.m202893200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have postulated the presence of a heparin-binding site on the bile salt-dependent lipase (BSDL), whereas two bile salt-binding sites regulate the enzyme activity. One of these sites may overlap with the tentative heparin-binding site at the level of an N-terminal basic cluster consisting of positive residues Lys(32), Lys(56), Lys(61), Lys(62), and Arg(63). The present study uses specific site-directed mutagenesis to determine the functional significance of this basic cluster. Mutations in this sequence resulted in recombinant enzymes that were able to bind to immobilized and to cell-associated heparin before moving throughout intestinal cells. Recombinant BSDL was fully active on soluble substrate, but mutants were less active on micellar cholesteryl oleate in comparison with the wild-type enzyme. Activation studies by primary (sodium taurocholate) and by secondary (sodium taurodeoxycholate) bile salts revealed that the activation of BSDL by sodium taurocholate at concentrations below the critical micellar concentration, and not that evoked by micellar bile salts, was affected by substitutions, suggesting that this N-terminal basic cluster likely represents the specific bile salt-binding site of BSDL. Substitutions also affected the activation of the enzyme promoted by anionic phospholipids, extending the function of this site to that of a cationic regulatory site susceptible to accommodate anionic ligands.
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Affiliation(s)
- Emeline Aubert
- INSERM U-559, Unité de Recherche de Physiopathologie des Cellules Epitheliales, Faculté de Médecine, 27 blv Jean MOULIN, 13385 Marseille cedex 05, France
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Perret B, Mabile L, Martinez L, Tercé F, Barbaras R, Collet X. Hepatic lipase:structure/function relationship, synthesis,and regulation. J Lipid Res 2002. [DOI: 10.1194/jlr.r100020-jlr200] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
Development of the lipase gene family spans the change in science that witnessed the birth of contemporary techniques of molecular biology. Amino acid sequencing of enzymes gave way to cDNA cloning and gene organization, augmented by in vitro expression systems and crystallization. This review traces the origins and highlights the functional significance of the lipase gene family, overlaid on the background of this technical revolution. The gene family initially consisted of three mammalian lipases [pancreatic lipase (PL), lipoprotein lipase, and hepatic lipase] based on amino acid sequence similarity and gene organization. Family size increased when several proteins were subsequently added based on amino acid homology, including PL-related proteins 1 and 2, phosphatidylserine phospholipase A1, and endothelial lipase. The physiological function of each of the members is discussed as well as the region responsible for lipase properties such as enzymatic activity, substrate binding, heparin binding, and cofactor interaction. Crystallization of several lipase gene family members established that the family belongs to a superfamily of enzymes, which includes esterases and thioesterases. This superfamily is related by tertiary structure, rather than amino acid sequence, and represents one of the most populous families found in nature.
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Affiliation(s)
- Howard Wong
- Lipid Research Laboratory, West Los Angeles Veterans Affairs Healthcare Center and Department of Medicine, University of California, Los Angeles, CA, USA.
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Foster TP, Melancon JM, Kousoulas KG. An alpha-helical domain within the carboxyl terminus of herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) is associated with cell fusion and resistance to heparin inhibition of cell fusion. Virology 2001; 287:18-29. [PMID: 11504538 DOI: 10.1006/viro.2001.1004] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies from our laboratory indicated that a 28-amino-acid carboxyl-terminal truncation of gB caused extensive virus-induced cell fusion (Baghian et al., 1993, J Virol 67, 2396-2401). We tested the ability of additional truncations and mutations within gB to cause cell fusion in the recently established virus-free cell fusion assay (Turner et al., 1998, J. Virol. 72, 873-875). Deletion of the carboxyl-terminal 28 amino acids of gB (gBDelta28), which removed part of the predicted alpha-helical structure H17b, caused extensive cell fusion. A gB truncation specified by gBDelta36, which removed the entire H17b domain, caused as much cell fusion as the gBDelta28 truncation. Similarly, gB(A874P) containing a substitution of an Ala with Pro within H17b caused cell fusion. Heparin, a gB-specific inhibitor of virus-induced cell fusion, inhibited both wild-type gB and gB(syn3)-mediated cell fusion. In contrast, fusion of cells transfected with gB(Delta28), gB(Delta36), or gB(A874P) was resistant to heparin inhibition of cell fusion. We concluded the following: (1) The predicted alpha-helical structure of H17b within the carboxyl terminus of gB is involved in both virus-induced and virus-free cell fusion. (2) Heparin is a specific inhibitor of gB-mediated fusion in both systems. (3) Resistance to heparin inhibition of gB-mediated cell fusion is associated with the predicted alpha-helical structure H17b within the carboxyl terminus of gB.
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Affiliation(s)
- T P Foster
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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