1
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Wheless A, Gunn KH, Neher SB. Macromolecular Interactions of Lipoprotein Lipase (LPL). Subcell Biochem 2024; 104:139-179. [PMID: 38963487 DOI: 10.1007/978-3-031-58843-3_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
Lipoprotein lipase (LPL) is a critical enzyme in humans that provides fuel to peripheral tissues. LPL hydrolyzes triglycerides from the cores of lipoproteins that are circulating in plasma and interacts with receptors to mediate lipoprotein uptake, thus directing lipid distribution via catalytic and non-catalytic functions. Functional losses in LPL or any of its myriad of regulators alter lipid homeostasis and potentially affect the risk of developing cardiovascular disease-either increasing or decreasing the risk depending on the mutated protein. The extensive LPL regulatory network tunes LPL activity to allocate fatty acids according to the energetic needs of the organism and thus is nutritionally responsive and tissue dependent. Multiple pharmaceuticals in development manipulate or mimic these regulators, demonstrating their translational importance. Another facet of LPL biology is that the oligomeric state of the enzyme is also central to its regulation. Recent structural studies have solidified the idea that LPL is regulated not only by interactions with other binding partners but also by self-associations. Here, we review the complexities of the protein-protein and protein-lipid interactions that govern LPL structure and function.
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Affiliation(s)
- Anna Wheless
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kathryn H Gunn
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Stony Brook University, Stony Brook, USA
| | - Saskia B Neher
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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2
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Crocco P, Vecchie D, Gopalkrishna S, Dato S, Passarino G, Young ME, Nagareddy PR, Rose G, De Luca M. Syndecan-4 as a genetic determinant of the metabolic syndrome. Diabetol Metab Syndr 2023; 15:156. [PMID: 37461091 PMCID: PMC10351106 DOI: 10.1186/s13098-023-01132-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 07/03/2023] [Indexed: 07/21/2023] Open
Abstract
BACKGROUND Syndecan-4 (SDC4) is a member of the heparan sulfate proteoglycan family of cell-surface receptors. We and others previously reported that variation in the SDC4 gene was associated with several components of the metabolic syndrome, including intra-abdominal fat, fasting glucose and triglyceride levels, and hypertension, in human cohorts. Additionally, we demonstrated that high fat diet (HFD)-induced obese female mice with a Sdc4 genetic deletion had higher visceral adiposity and a worse metabolic profile than control mice. Here, we aimed to first investigate whether the mouse Sdc4 null mutation impacts metabolic phenotypes in a sex- and diet-dependent manner. We then tested whether SDC4 polymorphisms are related to the metabolic syndrome (MetS) in humans. METHODS For the mouse experiment, Sdc4-deficient (Sdc4-/-) and wild-type (WT) mice were treated with 14-weeks of low-fat diet (LFD). Body composition, energy balance, and selected metabolic phenotypes were assessed. For the human genetic study, we used logistic regression models to test 11 SDC4 SNPs for association with the MetS and its components in a cohort of 274 (113 with MetS) elderly subjects from southern Italy. RESULTS Following the dietary intervention in mice, we observed that the effects of the Sdc4 null mutation on several phenotypes were different from those previously reported in the mice kept on an HFD. Nonetheless, LFD-fed female Sdc4-/- mice, but not males, displayed higher levels of triglycerides and lower insulin sensitivity at fasting than WT mice, as seen earlier in the HFD conditions. In the parallel human study, we found that carriers of SDC4 rs2228384 allele C and rs2072785 allele T had reduced risk of MetS. The opposite was true for carriers of the SDC4 rs1981429 allele G. Additionally, the SNPs were found related to fasting triglyceride levels and triglyceride glucose (TyG) index, a reliable indicator of insulin resistance, with sex-stratified analysis detecting the association of rs1981429 with these phenotypes only in females. CONCLUSIONS Altogether, our results suggest that SDC4 is an evolutionary conserved genetic determinant of MetS and that its genetic variation is associated with fasting triglyceride levels in a female-specific manner.
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Affiliation(s)
- Paolina Crocco
- Department of Biology, Ecology, and Earth Sciences, University of Calabria, Rende, 87036, Italy
| | - Denise Vecchie
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Sreejit Gopalkrishna
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Serena Dato
- Department of Biology, Ecology, and Earth Sciences, University of Calabria, Rende, 87036, Italy
| | - Giuseppe Passarino
- Department of Biology, Ecology, and Earth Sciences, University of Calabria, Rende, 87036, Italy
| | - Martin E Young
- Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Prabhakara R Nagareddy
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Giuseppina Rose
- Department of Biology, Ecology, and Earth Sciences, University of Calabria, Rende, 87036, Italy.
| | - Maria De Luca
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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3
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Roberts BS, Yang CQ, Neher SB. Characterization of lipoprotein lipase storage vesicles in 3T3-L1 adipocytes. J Cell Sci 2022; 135:jcs258734. [PMID: 34382637 PMCID: PMC8403984 DOI: 10.1242/jcs.258734] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/10/2021] [Indexed: 12/12/2022] Open
Abstract
Lipoprotein lipase (LPL) is a secreted triglyceride lipase involved in the clearance of very-low-density lipoproteins and chylomicrons from circulation. LPL is expressed primarily in adipose and muscle tissues and transported to the capillary lumen. LPL secretion is regulated by insulin in adipose tissue; however, few studies have examined the regulatory and trafficking steps involved in secretion. Here, we describe the intracellular localization and insulin-dependent trafficking of LPL in 3T3-L1 adipocytes. We compared LPL trafficking to the better characterized trafficking pathways taken by leptin and GLUT4 (also known as SLC2A4). We show that the LPL trafficking pathway shares some characteristics of these other pathways, but that LPL subcellular localization and trafficking are distinct from those of GLUT4 and leptin. LPL secretion occurs slowly in response to insulin and rapidly in response to the Ca2+ ionophore ionomycin. This regulated trafficking is dependent on Golgi protein kinase D and the ADP-ribosylation factor GTPase ARF1. Together, these data give support to a new trafficking pathway for soluble cargo that is active in adipocytes.
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Affiliation(s)
| | | | - Saskia B. Neher
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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4
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De Luca M, Mandala M, Rose G. Towards an understanding of the mechanoreciprocity process in adipocytes and its perturbation with aging. Mech Ageing Dev 2021; 197:111522. [PMID: 34147549 DOI: 10.1016/j.mad.2021.111522] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 05/29/2021] [Accepted: 06/15/2021] [Indexed: 12/25/2022]
Abstract
Adipose tissue (AT) is a complex organ, with multiple functions that are essential for maintaining metabolic health. A feature of AT is its capability to expand in response to physiological challenges, such as pregnancy and aging, and during chronic states of positive energy balance occurring throughout life. AT grows through adipogenesis and/or an increase in the size of existing adipocytes. One process that is required for healthy AT growth is the remodeling of the extracellular matrix (ECM), which is a necessary step to restore mechanical homeostasis and maintain tissue integrity and functionality. While the relationship between mechanobiology and adipogenesis is now well recognized, less is known about the role of adipocyte mechanosignaling pathways in AT growth. In this review article, we first summarize evidence linking ECM remodelling to AT expansion and how its perturbation is associated to a metabolically unhealthy phenotype. Subsequently, we highlight findings suggesting that molecules involved in the dynamic, bidirectional process (mechanoreciprocity) enabling adipocytes to sense changes in the mechanical properties of the ECM are interconnected to pathways regulating lipid metabolism. Finally, we discuss processes through which aging may influence the ability of adipocytes to appropriately respond to alterations in ECM composition.
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Affiliation(s)
- Maria De Luca
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Maurizio Mandala
- Department of Biology, Ecology and Earth Science, University of Calabria, Rende, 87036, Italy
| | - Giuseppina Rose
- Department of Biology, Ecology and Earth Science, University of Calabria, Rende, 87036, Italy
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5
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De Luca M, Bryan DR, Hunter GR. Circulating Levels of the Heparan Sulfate Proteoglycan Syndecan-4 Positively Associate with Blood Pressure in Healthy Premenopausal Women. Biomolecules 2021; 11:biom11030342. [PMID: 33668381 PMCID: PMC7996250 DOI: 10.3390/biom11030342] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 02/15/2021] [Accepted: 02/20/2021] [Indexed: 12/13/2022] Open
Abstract
Syndecans (SDCs) are transmembrane proteins that are present on most cell types where they play a role in multiple physiological processes, including cell-matrix adhesion and inflammation. Growing evidence suggests that elevated levels of both shed SDC1 and SDC4 are associated with hypertension and cardiovascular diseases, but their relationships with cardiovascular risk factors in healthy individuals are unknown. The primary objective of this study was to investigate whether serum levels of SDC4 and SDC1 were associated with body composition, hemodynamic parameters, pro-inflammatory cytokine concentrations, and urinary noradrenaline and dopamine levels in healthy women (17 African American and 20 European American) between the ages of 20 and 40 years old. Univariate analyses revealed only a significant (p < 0.05) inverse correlation between serum SDC1 and body fat percentage. On the other hand, serum SDC4 was positively correlated with systolic blood pressure, diastolic blood pressure, and urinary levels of noradrenaline and dopamine. Serum SDC4 was also a significant predictor of systolic blood pressure in a multivariate regression model that included fat-free mass and urinary dopamine levels as significant independent variables. The result did not change even adjusting for race. Our findings indicate that SDC4 has an important role in the physiological regulation of blood pressure.
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Affiliation(s)
- Maria De Luca
- Correspondence: ; Tel.: +1-205-934-7033; Fax: +1-205-934-7050
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6
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Pessentheiner AR, Ducasa GM, Gordts PLSM. Proteoglycans in Obesity-Associated Metabolic Dysfunction and Meta-Inflammation. Front Immunol 2020; 11:769. [PMID: 32508807 PMCID: PMC7248225 DOI: 10.3389/fimmu.2020.00769] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/06/2020] [Indexed: 12/16/2022] Open
Abstract
Proteoglycans are a specific subset of glycoproteins found at the cell surface and in the extracellular matrix, where they interact with a plethora of proteins involved in metabolic homeostasis and meta-inflammation. Over the last decade, new insights have emerged on the mechanism and biological significance of these interactions in the context of diet-induced disorders such as obesity and type-2 diabetes. Complications of energy metabolism drive most diet-induced metabolic disorders, which results in low-grade chronic inflammation, thereby affecting proper function of many vital organs involved in energy homeostasis, such as the brain, liver, kidney, heart and adipose tissue. Here, we discuss how heparan, chondroitin and keratan sulfate proteoglycans modulate obesity-induced metabolic dysfunction and low-grade inflammation that impact the initiation and progression of obesity-associated morbidities.
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Affiliation(s)
- Ariane R. Pessentheiner
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA, United States
| | - G. Michelle Ducasa
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA, United States
| | - Philip L. S. M. Gordts
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA, United States
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, United States
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7
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Gougoula C, Bielfeld AP, Pour SJ, Sager M, Krüssel JS, Benten WPM, Baston-Büst DM. Metabolic and behavioral parameters of mice with reduced expression of Syndecan-1. PLoS One 2019; 14:e0219604. [PMID: 31299063 PMCID: PMC6625734 DOI: 10.1371/journal.pone.0219604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/27/2019] [Indexed: 11/19/2022] Open
Abstract
Energy balance is essential for all species. Ligand-receptor interactions mediate processes that regulate body activities like reproduction and metabolism based on the energy status. Such receptors are the heparan sulfate proteoglycans and specifically the family of syndecans. Therefore we investigated the differences of metabolic parameters of heterozygous Syndecan 1 mice (Sdc1+/-) with reduced expression of Sdc1 and the corresponding wild type mice. Sdc1+/- mice have a reduced body weight although they show increased leptin and decreased corticosterone levels. Furthermore, their food and water intake is increased. This is accompanied with less adipose tissue, smaller adipocytes and thus an increased density of adipocytes. For the detailed analysis of the metabolism the automated PhenoMaster system has been used, which allowed continuous and undisturbed recording of food and water intake, energy expenditure and movement. The reason for the lower body weight was the higher energy expenditure of these animals compared to controls. Additionally, female Sdc1+/- mice showed an increased locomotor activity. Referring to organs, the intestine in Sdc1+/- mice was heavier and longer, but no differences at the cellular level could be observed. These findings were independent of normal mating or vice versa embryo transfers of Sdc1+/- and wild type embryos in recipient females of the other genotype. Herein we showed that the reduced expression of Sdc1 led to an altered metabolism on fetal as well as on maternal side, which may play a role in the growth restriction observed in human pregnancy pathologies and in mice lacking Sdc1.
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Affiliation(s)
- Christina Gougoula
- Central Unit for Animal Research and Animal Welfare Affairs (ZETT) of the Heinrich-Heine-University of Düsseldorf, Düsseldorf, Germany
| | | | - Sarah Jean Pour
- Düsseldorf University Hospital, Department of OB/GYN and REI (UniKiD), Düsseldorf, Germany
| | - Martin Sager
- Central Unit for Animal Research and Animal Welfare Affairs (ZETT) of the Heinrich-Heine-University of Düsseldorf, Düsseldorf, Germany
| | - Jan-Steffen Krüssel
- Düsseldorf University Hospital, Department of OB/GYN and REI (UniKiD), Düsseldorf, Germany
| | - Wilhelm Peter M. Benten
- Central Unit for Animal Research and Animal Welfare Affairs (ZETT) of the Heinrich-Heine-University of Düsseldorf, Düsseldorf, Germany
| | - Dunja Maria Baston-Büst
- Düsseldorf University Hospital, Department of OB/GYN and REI (UniKiD), Düsseldorf, Germany
- * E-mail:
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8
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Agere SA, Kim EY, Akhtar N, Ahmed S. Syndecans in chronic inflammatory and autoimmune diseases: Pathological insights and therapeutic opportunities. J Cell Physiol 2018; 233:6346-6358. [PMID: 29226950 DOI: 10.1002/jcp.26388] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/04/2017] [Indexed: 12/20/2022]
Abstract
Syndecans (SDCs) are a family of heparan sulfate proteoglycans (HSPGs) glycoproteins ubiquitously expressed on the cell surfaces and extracellular matrix of all mammalian tissues. There are four mammalian syndecans, SDC-1 thorough 4, which play a critical role in cell adhesion, migration, proliferation, differentiation, and angiogenesis through independent and growth factor mediated signaling. An altered expression of SDCs is often observed in autoimmune disorders, cancer, HIV infection, and many other pathological conditions. SDCs modulate disease progression by interacting with a diverse array of ligands, receptors, and other proteins, including extracellular matrix, glycoproteins, integrins, morphogens, and various growth factors and chemokines, along with their receptors and kinases. Specifically, SDCs present on cell surface can bind directly to chemokines to enhance their binding to receptors, downstream signaling, and migration. Alternatively, SDCs can be cleaved and shed to mediate negative regulation of chemokine and growth factor signaling pathways and ligand sequestration. Importantly, SDC shedding may be a biomarker of inflammation, especially in chronic inflammatory diseases. While the current therapies for cancer and several autoimmune disorders have revolutionized treatment outcomes, understanding the pathophysiological role of SDCs and the use of HSPG mimetic or antagonists on cytokine signaling networks may uncover potentially novel targeted therapeutic approaches. This review mainly summarizes the current findings on the role of individual SDCs in disease processes, mechanisms through which SDCs mediate their biological functions, and the possibility of targeting SDCs as future potential therapeutic approaches.
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Affiliation(s)
- Solomon A Agere
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington
| | - Eugene Y Kim
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington
| | - Nahid Akhtar
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington
| | - Salahuddin Ahmed
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington.,Division of Rheumatology, University of Washington School of Medicine, Seattle, Washington
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9
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Rose G, Crocco P, De Rango F, Corsonello A, Lattanzio F, De Luca M, Passarino G. Metabolism and successful aging: Polymorphic variation of syndecan-4 (SDC4) gene associate with longevity and lipid profile in healthy elderly Italian subjects. Mech Ageing Dev 2015; 150:27-33. [PMID: 26254886 DOI: 10.1016/j.mad.2015.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 07/27/2015] [Accepted: 08/03/2015] [Indexed: 11/25/2022]
Abstract
Evidences from model systems and humans have suggested that genetic alterations in cell-ECM interactions and matrix-mediated cellular signaling cascades impact different aspects of metabolism and thereby life span. In this frame, a genetic variant (rs1981429) in the SDC4 gene encoding for syndecan-4, a central mediator of cell adhesion, has been associated with body composition in children and coronary artery disease in middle-age subjects. In order to test the hypothesis that syndecans might affect life span by affecting metabolic endophenotypes, 11 SNPs within the SDC4 gene were tested for association with longevity in a cohort of 64-107 aged individuals. We then determined whether the longevity-associated SNPs were correlated with metabolic parameters in the age group 64-85 years. RobustSNP association tests showed that rs1981429 was negatively associated with longevity (Theop=0.028), but also with high levels of triglyceride (Theop=0.028) and low levels of low-density lipoprotein-cholesterol (LDL-C) (Theop=0.009). On the other hand, rs2251252 was found to be positively correlated with longevity (Theop=0.018) and high LDL-C (Theop=0.022). On the whole, our results suggest that SDC4 alleles affect lipid profile in elderly subjects and may in part mediate the link between LDL-C and longevity.
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Affiliation(s)
- Giuseppina Rose
- Department of Biology, Ecology and Earth Science, University of Calabria, Rende 87036, Italy.
| | - Paolina Crocco
- Department of Biology, Ecology and Earth Science, University of Calabria, Rende 87036, Italy
| | - Francesco De Rango
- Department of Biology, Ecology and Earth Science, University of Calabria, Rende 87036, Italy
| | | | - Fabrizia Lattanzio
- Scientific Direction of the Italian National Research Centre on Ageing, Ancona 6100, Italy
| | - Maria De Luca
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Giuseppe Passarino
- Department of Biology, Ecology and Earth Science, University of Calabria, Rende 87036, Italy
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10
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Zaragosi LE, Dadone B, Michiels JF, Marty M, Pedeutour F, Dani C, Bianchini L. Syndecan-1 regulates adipogenesis: new insights in dedifferentiated liposarcoma tumorigenesis. Carcinogenesis 2014; 36:32-40. [PMID: 25344834 DOI: 10.1093/carcin/bgu222] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Syndecan-1 (SDC1/CD138) is one of the main cell surface proteoglycans and is involved in crucial biological processes. Only a few studies have analyzed the role of SDC1 in mesenchymal tumor pathogenesis. In particular, its involvement in adipose tissue tumors has never been investigated. Dedifferentiated liposarcoma, one of the most frequent types of malignant adipose tumors, has a high potential of recurrence and metastastic evolution. Classical chemotherapy is inefficient in metastatic dedifferentiated liposarcoma and novel biological markers are needed for improving its treatment. In this study, we have analyzed the expression of SDC1 in well-differentiated/dedifferentiated liposarcomas and showed that SDC1 is highly overexpressed in dedifferentiated liposarcoma compared with normal adipose tissue and lipomas. Silencing of SDC1 in liposarcoma cells impaired cell viability and proliferation. Using the human multipotent adipose-derived stem cell model of human adipogenesis, we showed that SDC1 promotes proliferation of undifferentiated adipocyte progenitors and inhibits their adipogenic differentiation. Altogether, our results support the hypothesis that SDC1 might be involved in liposarcomagenesis. It might play a prominent role in the dedifferentiation process occurring when well-differentiated liposarcoma progress to dedifferentiated liposarcoma. Targeting SDC1 in these tumors might provide a novel therapeutic strategy.
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Affiliation(s)
- Laure-Emmanuelle Zaragosi
- Institute of Biology Valrose, UMR7277 CNRS/UMR1091 INSERM/University of Nice-Sophia Antipolis, 06108 Nice, France, Present address: CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, University of Nice- Sophia Antipolis, 06560 Sophia Antipolis, France
| | - Bérengère Dadone
- Department of Pathology, Nice University Hospital, 06202 Nice, France, Institute for Research on Cancer and Aging of Nice, CNRS UMR 7284/INSERM U1081, University of Nice-Sophia Antipolis, 06107 Nice, France, Laboratory of Solid Tumor Genetics, Nice University Hospital, 06107 Nice, France and
| | - Jean-François Michiels
- Department of Pathology, Nice University Hospital, 06202 Nice, France, Institute for Research on Cancer and Aging of Nice, CNRS UMR 7284/INSERM U1081, University of Nice-Sophia Antipolis, 06107 Nice, France
| | - Marion Marty
- Department of Pathology, Bordeaux University Hospital, 33076 Bordeaux, France
| | - Florence Pedeutour
- Institute for Research on Cancer and Aging of Nice, CNRS UMR 7284/INSERM U1081, University of Nice-Sophia Antipolis, 06107 Nice, France, Laboratory of Solid Tumor Genetics, Nice University Hospital, 06107 Nice, France and
| | - Christian Dani
- Institute of Biology Valrose, UMR7277 CNRS/UMR1091 INSERM/University of Nice-Sophia Antipolis, 06108 Nice, France
| | - Laurence Bianchini
- Institute for Research on Cancer and Aging of Nice, CNRS UMR 7284/INSERM U1081, University of Nice-Sophia Antipolis, 06107 Nice, France,
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11
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Reprint of "Alteration of endothelial proteoglycan and heparanase gene expression by high glucose, insulin and heparin". Vascul Pharmacol 2014. [DOI: 10.1016/j.vph.2014.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Kasza I, Suh Y, Wollny D, Clark RJ, Roopra A, Colman RJ, MacDougald OA, Shedd TA, Nelson DW, Yen MI, Yen CLE, Alexander CM. Syndecan-1 is required to maintain intradermal fat and prevent cold stress. PLoS Genet 2014; 10:e1004514. [PMID: 25101993 PMCID: PMC4125098 DOI: 10.1371/journal.pgen.1004514] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 06/05/2014] [Indexed: 02/07/2023] Open
Abstract
Homeostatic temperature regulation is fundamental to mammalian physiology and is controlled by acute and chronic responses of local, endocrine and nervous regulators. Here, we report that loss of the heparan sulfate proteoglycan, syndecan-1, causes a profoundly depleted intradermal fat layer, which provides crucial thermogenic insulation for mammals. Mice without syndecan-1 enter torpor upon fasting and show multiple indicators of cold stress, including activation of the stress checkpoint p38α in brown adipose tissue, liver and lung. The metabolic phenotype in mutant mice, including reduced liver glycogen, is rescued by housing at thermoneutrality, suggesting that reduced insulation in cool temperatures underlies the observed phenotypes. We find that syndecan-1, which functions as a facultative lipoprotein uptake receptor, is required for adipocyte differentiation in vitro. Intradermal fat shows highly dynamic differentiation, continuously expanding and involuting in response to hair cycle and ambient temperature. This physiology probably confers a unique role for Sdc1 in this adipocyte sub-type. The PPARγ agonist rosiglitazone rescues Sdc1−/− intradermal adipose tissue, placing PPARγ downstream of Sdc1 in triggering adipocyte differentiation. Our study indicates that disruption of intradermal adipose tissue development results in cold stress and complex metabolic pathology. All mammals strive to maintain a fixed body temperature, and do so using a remarkable array of different strategies, which vary depending upon the degree of cold challenge. Physiologists many decades ago observed that a fat layer right underneath the epidermis (and above the dermal muscle layer) thickens in response to colder ambient temperatures. This “intradermal fat” provided insulation within days of climate changes. We have found that syndecan-1, which functions as a facultative lipoprotein uptake receptor, is required for intradermal fat expansion in response to cold exposure. This is a highly specific phenotype not shared by other adipocytes. When intradermal fat is absent, mice do not adapt normally to cold stress, and show altered systemic physiologies, including increased brown adipose tissue thermogenesis and hyper-activation of a stress checkpoint (p38α), designed to protect the body against mutagenic and oxidative stressors. The phenotypes associated with loss of Sdc1 function are reversed when mice are housed in warm temperatures, where defense of body temperature is not required. This study is the first to show that intradermal fat can be genetically regulated, with systemic effects on physiology.
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Affiliation(s)
- Ildiko Kasza
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Yewseok Suh
- Department of Dermatology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Damian Wollny
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Rod J. Clark
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Avtar Roopra
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Ricki J. Colman
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
| | - Ormond A. MacDougald
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Timothy A. Shedd
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - David W. Nelson
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Mei-I Yen
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Chi-Liang Eric Yen
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Caroline M. Alexander
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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13
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Landgraf P, Mikhaylova M, Macharadze T, Borutzki C, Zenclussen AC, Wahle P, Kreutz MR. Binding of Y-P30 to syndecan 2/3 regulates the nuclear localization of CASK. PLoS One 2014; 9:e85924. [PMID: 24498267 PMCID: PMC3911912 DOI: 10.1371/journal.pone.0085924] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Accepted: 12/03/2013] [Indexed: 12/02/2022] Open
Abstract
The survival promoting peptide Y-P30 has documented neuroprotective effects as well as cell survival and neurite outgrowth promoting activity in vitro and in vivo. Previous work has shown that multimerization of the peptide with pleiotrophin (PTN) and subsequent binding to syndecan (SDC) -2 and -3 is involved in its neuritogenic effects. In this study we show that Y-P30 application regulates the nuclear localization of the SDC binding partner Calcium/calmodulin-dependent serine kinase (CASK) in neuronal primary cultures during development. In early development at day in vitro (DIV) 8 when mainly SDC-3 is expressed supplementation of the culture medium with Y-P30 reduces nuclear CASK levels whereas it has the opposite effect at DIV 18 when SDC-2 is the dominant isoform. In the nucleus CASK regulates gene expression via its association with the T-box transcription factor T-brain-1 (Tbr-1) and we indeed found that gene expression of downstream targets of this complex, like the GluN2B NMDA-receptor, exhibits a corresponding down- or up-regulation at the mRNA level. The differential effect of Y-P30 on the nuclear localization of CASK correlates with its ability to induce shedding of the ectodomain of SDC-2 but not -3. shRNA knockdown of SDC-2 at DIV 18 and SDC-3 at DIV 8 completely abolished the effect of Y-P30 supplementation on nuclear CASK levels. During early development a protein knockdown of SDC-3 also attenuated the effect of Y-P30 on axon outgrowth. Taken together these data suggest that Y-P30 can control the nuclear localization of CASK in a SDC-dependent manner.
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Affiliation(s)
- Peter Landgraf
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Marina Mikhaylova
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Tamar Macharadze
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Corinna Borutzki
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Ana-Claudia Zenclussen
- Department of Experimental Obstetrics and Gynaecology, Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany
| | - Petra Wahle
- Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University, Bochum, Germany
| | - Michael R Kreutz
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
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Han J, Hiebert LM. Alteration of endothelial proteoglycan and heparanase gene expression by high glucose, insulin and heparin. Vascul Pharmacol 2013; 59:112-8. [PMID: 23939434 DOI: 10.1016/j.vph.2013.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 07/16/2013] [Accepted: 08/02/2013] [Indexed: 11/25/2022]
Abstract
Heparan sulfate proteoglycans (HSPGs) contain a core protein with glycosaminoglycans attached. Reduced glycosaminoglycan, in endothelial HSPGs syndecan and perlecan, is associated with diabetic cardiovascular complications but changes in core protein remain controversial. Since heparanase degrades heparan sulfate, we wished to determine if changes in endothelial heparanase mRNA, by high glucose (HG), correlate with changes in syndecan and perlecan core proteins, and to observe effects of heparin or insulin. RNA was isolated from cultured human aortic endothelial cells treated with HG (30mM), insulin (0.01 units/mL), heparin (0.5μg/mL), HG plus heparin and/or insulin for 24h. Real time PCR revealed that HG alone significantly increased heparanase, decreased syndecan with no effect on perlecan mRNA. Heparin or insulin significantly prevented the increase in heparanase but decreased perlecan mRNA while heparin, but not insulin, prevented the decrease in syndecan mRNA in HG treated cells. HG plus heparin and insulin increased heparanase and syndecan mRNA compared to all other treatments and decreased perlecan mRNA compared to control and HG alone. Heparin may protect endothelium from HG injury by reducing heparanase and increasing syndecan while insulin inhibits heparanase expression. Effects with insulin plus heparin suggest interference in transcriptional regulation of heparanase and syndecan genes.
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Affiliation(s)
- J Han
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5B4, Canada
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15
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Tan X, Khalil N, Tesarik C, Vanapalli K, Yaputra V, Alkhouri H, Oliver BGG, Armour CL, Hughes JM. Th1 cytokine-induced syndecan-4 shedding by airway smooth muscle cells is dependent on mitogen-activated protein kinases. Am J Physiol Lung Cell Mol Physiol 2012; 302:L700-10. [PMID: 22268118 DOI: 10.1152/ajplung.00167.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In asthma, airway smooth muscle (ASM) chemokine secretion can induce mast cell recruitment into the airways. The functions of the mast cell chemoattractant CXCL10, and other chemokines, are regulated by binding to heparan sulphates such as syndecan-4. This study is the first demonstration that airway smooth muscle cells (ASMC) from people with and without asthma express and shed syndecan-4 under basal conditions. Syndecan-4 shedding was enhanced by stimulation for 24 h with the Th1 cytokines interleukin-1β (IL-1β) or tumor necrosis factor-α (TNF-α), but not interferon-γ (IFNγ), nor the Th2 cytokines IL-4 and IL-13. ASMC stimulation with IL-1β, TNF-α, and IFNγ (cytomix) induced the highest level of syndecan-4 shedding. Nonasthmatic and asthmatic ASM cell-associated syndecan-4 protein expression was also increased by TNF-α or cytomix at 4-8 h, with the highest levels detected in cytomix-stimulated asthmatic cells. Cell-associated syndecan-4 levels were decreased by 24 h, whereas shedding remained elevated at 24 h, consistent with newly synthesized syndecan-4 being shed. Inhibition of ASMC matrix metalloproteinase-2 did not prevent syndecan-4 shedding, whereas inhibition of ERK MAPK activation reduced shedding from cytomix-stimulated ASMC. Although ERK inhibition had no effect on syndecan-4 mRNA levels stimulated by cytomix, it did cause an increase in cell-associated syndecan-4 levels, consistent with the shedding being inhibited. In conclusion, ASMC produce and shed syndecan-4 and although this is increased by the Th1 cytokines, the MAPK ERK only regulates shedding. ASMC syndecan-4 production during Th1 inflammatory conditions may regulate chemokine activity and mast cell recruitment to the ASM in asthma.
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16
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Deng Y, Foley EM, Gonzales JC, Gordts PL, Li Y, Esko JD. Shedding of syndecan-1 from human hepatocytes alters very low density lipoprotein clearance. Hepatology 2012; 55:277-86. [PMID: 21898481 PMCID: PMC3245353 DOI: 10.1002/hep.24626] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Accepted: 08/16/2011] [Indexed: 01/07/2023]
Abstract
UNLABELLED We recently showed that the heparan sulfate proteoglycan syndecan-1 mediates hepatic clearance of triglyceride-rich lipoproteins in mice based on systemic deletion of syndecan-1 and hepatocyte-specific inactivation of sulfotransferases involved in heparan sulfate biosynthesis. Here, we show that syndecan-1 expressed on primary human hepatocytes and Hep3B human hepatoma cells can mediate binding and uptake of very low density lipoprotein (VLDL). Syndecan-1 also undergoes spontaneous shedding from primary human and murine hepatocytes and Hep3B cells. In human cells, phorbol myristic acid induces syndecan-1 shedding, resulting in accumulation of syndecan-1 ectodomains in the medium. Shedding occurs through a protein kinase C-dependent activation of ADAM17 (a disintegrin and metalloproteinase 17). Phorbol myristic acid stimulation significantly decreases DiD (1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine perchlorate)-VLDL binding to cells, and shed syndecan-1 ectodomains bind to VLDL. Although mouse hepatocytes appear resistant to induced shedding in vitro, injection of lipopolysaccharide into mice results in loss of hepatic syndecan-1, accumulation of ectodomains in the plasma, impaired VLDL catabolism, and hypertriglyceridemia. CONCLUSION These findings suggest that syndecan-1 mediates hepatic VLDL turnover in humans as well as in mice and that shedding might contribute to hypertriglyceridemia in patients with sepsis.
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Affiliation(s)
- Yiping Deng
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA,The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Erin M. Foley
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA,Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA
| | - Jon C. Gonzales
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA,Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA
| | - Philip L. Gordts
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
| | - Yulin Li
- The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Jeffrey D. Esko
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA,Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA,Author to whom proofs should be sent: Jeffrey D. Esko, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0687, Ph: 858-822-1100, Fx: 858-534-5611,
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Abstract
Membrane-bound proteoglycans function primarily as coreceptors for many glycosaminoglycan (GAG)-binding ligands at the cell surface. The majority of membrane-bound proteoglycans can also function as soluble autocrine or paracrine effectors as their extracellular domains, replete with all GAG chains, are enzymatically cleaved and released from the cell surface by ectodomain shedding. In particular, the ectodomain shedding of syndecans, a major family of cell surface heparan sulfate proteoglycans, is an important posttranslational mechanism that modulates diverse pathophysiological processes. Syndecan shedding is a tightly controlled process that regulates the onset, progression, and resolution of various infectious and noninfectious inflammatory diseases. This review describes methods to induce and measure the shedding of cell membrane-bound proteoglycans, focusing on syndecan shedding as a prototypic example.
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Affiliation(s)
- Eon Jeong Nam
- Division of Respiratory Diseases, Children's Hospital, Harvard Medical School, Boston, MA, USA
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Yamamoto T, Suganami T, Kiso-Narita M, Scherle PA, Kamei Y, Isobe M, Higashiyama S, Ogawa Y. Insulin-induced ectodomain shedding of heparin-binding epidermal growth factor-like growth factor in adipocytes in vitro. Obesity (Silver Spring) 2010; 18:1888-94. [PMID: 20111015 DOI: 10.1038/oby.2010.2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is synthesized as a type I transmembrane protein, which is proteolytically cleaved to release a soluble form via members of the a disintegrin and metalloproteinase (ADAM) family of proteolytic enzymes. This study was designed to elucidate the molecular mechanism underlying insulin-induced HB-EGF shedding in adipocytes in vitro. The 3T3-L1 adipocytes with stable expression of alkaline phosphatase (AP)-tagged proHB-EGF (3T3-L1/HB-EGF-AP adipocytes) were developed and AP activities of conditioned media were determined. Using 3T3-L1/HB-EGF-AP adipocytes, we demonstrated that insulin induces HB-EGF shedding in differentiated 3T3-L1 adipocytes in a dose- and time-dependent manner. There is no significant increase in insulin-induced HB-EGF shedding in undifferentiated 3T3-L1 preadipocytes. Studies with metalloprotease inhibitors suggested that insulin-induced HB-EGF shedding in adipocytes is mediated at least in part via ADAM17. Treatment with recombinant HB-EGF results in a dose- and time-dependent increase in HB-EGF shedding in adipocytes, which is significantly suppressed by pharmacologic blockade of ADAM17 (P < 0.01). Moreover, insulin-induced HB-EGF shedding in adipocytes is significantly inhibited by AG1478, an EGF receptor antagonist (P < 0.01). This study provides in vitro evidence that insulin induces HB-EGF shedding in 3T3-L1 adipocytes. Our data also suggest the role of ADAM17 in insulin-induced HB-EGF shedding in adipocytes.
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Affiliation(s)
- Takanobu Yamamoto
- Department of Molecular Medicine and Metabolism, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
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20
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Choi S, Lee H, Choi JR, Oh ES. Shedding; towards a new paradigm of syndecan function in cancer. BMB Rep 2010; 43:305-10. [PMID: 20510012 DOI: 10.5483/bmbrep.2010.43.5.305] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Syndecans, cell surface heparansulfate proteoglycans, have been proposed to act as cell surface receptors and/or coreceptors to play critical roles in multiple cellular functions. However, recent reports suggest that the function of syndecans can be further extended through shedding, a cleavage of extracellular domain. Shedding constitutes an additional level for controlling the function of syndecans, providing a means to attenuate and/or regulate amplitude and duration of syndecan signals by modulating the activity of syndecans as cell surface receptors. Whether these remaining cleavage products are still capable of functioning as cell surface receptors to efficiently transduce signals inside of cells is not clear. However, shedding transforms cell surface receptor syndecans into soluble forms, which, like growth factors, may act as novel ligands to induce cellular responses by association with other cell surface receptors. It is becoming interestingly evident that shed syndecans also contribute significantly to syndecan functions in cancer biology. This review presents current knowledge about syndecan shedding and its functional significance, particularly in the context of cancer.
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Affiliation(s)
- Sojoong Choi
- Department of Life Sciences, Center for Cell Signaling and Drug Discovery Research, Ewha Womans University, Seoul, Korea
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21
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Wang JB, Guan J, Shen J, Zhou L, Zhang YJ, Si YF, Yang L, Jian XH, Sheng Y. Insulin increases shedding of syndecan-1 in the serum of patients with type 2 diabetes mellitus. Diabetes Res Clin Pract 2009; 86:83-8. [PMID: 19735958 DOI: 10.1016/j.diabres.2009.08.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2009] [Revised: 08/03/2009] [Accepted: 08/13/2009] [Indexed: 01/04/2023]
Abstract
AIMS To detect the level of serum syndecan-1 of patients with type 2 diabetes. METHODS Subjects with diabetes were categorized into 4 subgroups, oral-agents, insulin therapy for <or=1 month, 1-12 months, and >12 months. Serum syndecan-1 was detected by ELISA, and potential correlation between syndecan-1 levels and clinical characteristics was analyzed. RESULTS Sixty-two diabetic patients and 20 healthy subjects (controls) were enrolled. Syndecan-1 in diabetic patients (24.616+/-1.993 ng/ml) was higher than that of the controls (18.907+/-2.638 ng/ml). The average concentration of syndecan-1 in the group of oral-agents, insulin therapy for <or=1 month, 1-12 months, and >12 months was 19.157+/-2.556 ng/ml (n=20), 24.447+/-3.173 ng/ml (n=23), 35.005+/-4.749 ng/ml (n=11), and 27.593+/-8.304 ng/ml (n=8), respectively. An association between serum syndecan-1 and intake of exogenous insulin was found (r=0.266, p=0.035). Serum syndecan-1 of insulin-therapy group (27.811+/-2.669 ng/ml) enhanced significantly compared to that of the controls (p=0.030) and that of the oral-agents group (p=0.035). Syndecan-1 of the insulin therapy for 1-12 months group enhanced predominantly compared to that of the controls (p=0.005) and the oral-agents group (p=0.005). CONCLUSIONS Chronic inflammation and exogenous insulin usage increases serum syndecan-1 level. Exogenous insulin can promote shedding of syndecan-1 ectodomains to the serum in a time-dependent manner.
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Affiliation(s)
- Jing-bo Wang
- Department of Ophthalmology, The 309th Hospital of Chinese People's Liberation Army, Haidian District, Beijing 100091, China.
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Han J, Zhang F, Xie J, Linhardt RJ, Hiebert LM. Changes in cultured endothelial cell glycosaminoglycans under hyperglycemic conditions and the effect of insulin and heparin. Cardiovasc Diabetol 2009; 8:46. [PMID: 19695080 PMCID: PMC2739842 DOI: 10.1186/1475-2840-8-46] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 08/20/2009] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Heparan sulfate proteoglycans (HSPGs) contain glycosaminoglycan (GAG) chains made primarily of heparan sulfate (HS). Hyperglycemia in diabetes leads to endothelial injury and nephropathy, retinopathy and atherosclerosis. Decreased HSPG may contribute to diabetic endothelial injury. Decreased tissue HS in diabetes has been reported, however, endothelial HS changes are poorly studied. OBJECTIVE To determine total GAGs, including HS, in endothelium under hyperglycemic conditions and the protective effect of insulin and heparin. METHODS Confluent primary porcine aortic endothelial cells (PAECs) were divided into control, glucose (30 mM), insulin (0.01 unit/ml) and glucose plus insulin treatment groups for 24, 48 and 72 hours. Additionally, PAECs were treated with glucose, heparin (0.5 microg/ml) and glucose plus heparin for 72 hours. GAGs were isolated from cells and medium. GAG concentrations were determined by the carbazole assay and agarose gel electrophoresis. RESULTS GAGs were significantly increased only in control and glucose plus insulin groups at 72 versus 24 hours. Glucose decreased cell GAGs and increased medium GAGs, and insulin alone decreased cell GAGs at all times compared to control. In the glucose plus insulin group, cell GAGs were less than control at 24 hours, and greater than glucose or insulin alone at 48 and 72 hours while GAGs in medium were greater than control at all times and glucose at 72 hours. Heparin increased GAGs in glucose treated cells and medium. CONCLUSION High glucose and insulin alone reduces endothelial GAGs. In hyperglycemic conditions, heparin or insulin preserves GAGs which may protect cells from injury. Insulin is an effective diabetic therapy since it not only lowers blood glucose, but also protects endothelium.
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Affiliation(s)
- Juying Han
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada.
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Schubert D, Herrera F, Cumming R, Read J, Low W, Maher P, Fischer WH. Neural cells secrete a unique repertoire of proteins. J Neurochem 2009; 109:427-35. [PMID: 19200335 DOI: 10.1111/j.1471-4159.2009.05968.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proteins that are released from cells consist of those in the extracellular matrix, as well as extracellular signaling and adhesion molecules. The majority of these extracellular proteins are, however, unknown. To determine their identity, we have used a proteomics approach to define proteins released from neurons, astrocytes and neural precursor cells. Using two-dimensional gels and liquid chromatography/mass spectrometry technology, it is shown that while astrocytes release a relatively small number of proteins, neurons and neuronal precursor cells release a larger number of proteins with more functional diversity. Although there is overlap between the different cell types, the exact composition of the extracellular protein pool is unique for each cell population. The various subsets of extracellular neural proteins include those involved in cellular Redox regulation and chaperones. In addition, many proteolytic enzymes are found outside of the cell. These data show that the extracellular space within the nervous system has a more diverse protein composition than previously thought.
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Affiliation(s)
- David Schubert
- The Salk Institute for Biological Studies, La Jolla, California 92037-1099, USA
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24
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Bibliography. Current world literature. Diabetes and the endocrine pancreas II. Curr Opin Endocrinol Diabetes Obes 2007; 14:329-57. [PMID: 17940461 DOI: 10.1097/med.0b013e3282c3a898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Tan GD, Olivecrona G, Vidal H, Frayn KN, Karpe F. Insulin sensitisation affects lipoprotein lipase transport in type 2 diabetes: role of adipose tissue and skeletal muscle in response to rosiglitazone. Diabetologia 2006; 49:2412-8. [PMID: 16896939 DOI: 10.1007/s00125-006-0370-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 05/30/2006] [Indexed: 10/24/2022]
Abstract
AIMS/HYPOTHESIS Lipoprotein lipase (LPL) is produced by adipose tissue and skeletal muscle, but acts on plasma lipoproteins after being transported to endothelial binding sites. Insulin resistance is associated with decreased plasma LPL mass. We investigated the effects of insulin sensitisation on tissue-specific LPL expression and transport in patients with type 2 diabetes. MATERIALS AND METHODS Arterio-venous gradients of plasma LPL activity and mass across adipose tissue and skeletal muscle were measured in 16 type 2 diabetic patients in a double-blind, placebo-controlled, cross-over randomised trial of rosiglitazone. In vivo LPL rate of action was assessed by tissue-specific arterio-venous triglyceride concentration gradients. LPL mRNA was quantified in adipose tissue and skeletal muscle biopsies. RESULTS Adipose tissue released large quantities of inactive LPL (p<0.001); skeletal muscle released small amounts of active LPL (p<0.01). Rosiglitazone increased adipose tissue release of LPL mass (+35%, p=0.04) and decreased the release of active LPL from skeletal muscle (-57%, p=0.03). Rosiglitazone increased adipose tissue and skeletal muscle LPL mRNA, but did not affect adipose tissue LPL rate of action or activity. Adipose tissue release of LPL mass correlated with systemic LPL mass concentrations (r=0.47, p=0.007), suggesting that the rate of adipose tissue release of LPL mass is a major determinant of systemic LPL mass concentrations. CONCLUSIONS/INTERPRETATION LPL transport from adipose tissue and skeletal muscle are regulated differently. In adipose tissue, rosiglitazone increases LPL mRNA abundance and LPL transport rate and possibly increases endothelial binding sites for LPL, but affects neither tissue LPL activity nor LPL rate of action.
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Affiliation(s)
- G D Tan
- OCDEM, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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