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Rakhshandehroo M, van Eijkeren RJ, Gabriel TL, de Haar C, Gijzel SMW, Hamers N, Ferraz MJ, Aerts JMFG, Schipper HS, van Eijk M, Boes M, Kalkhoven E. Adipocytes harbor a glucosylceramide biosynthesis pathway involved in iNKT cell activation. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1157-1167. [PMID: 31051284 DOI: 10.1016/j.bbalip.2019.04.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 12/27/2022]
Abstract
BACKGROUND Natural killer T (NKT) cells in adipose tissue (AT) contribute to whole body energy homeostasis. RESULTS Inhibition of the glucosylceramide synthesis in adipocytes impairs iNKT cell activity. CONCLUSION Glucosylceramide biosynthesis pathway is important for endogenous lipid antigen activation of iNKT cells in adipocytes. SIGNIFICANCE Unraveling adipocyte-iNKT cell communication may help to fight obesity-induced AT dysfunction. Overproduction and/or accumulation of ceramide and ceramide metabolites, including glucosylceramides, can lead to insulin resistance. However, glucosylceramides also fulfill important physiological functions. They are presented by antigen presenting cells (APC) as endogenous lipid antigens via CD1d to activate a unique lymphocyte subspecies, the CD1d-restricted invariant (i) natural killer T (NKT) cells. Recently, adipocytes have emerged as lipid APC that can activate adipose tissue-resident iNKT cells and thereby contribute to whole body energy homeostasis. Here we investigate the role of the glucosylceramide biosynthesis pathway in the activation of iNKT cells by adipocytes. UDP-glucose ceramide glucosyltransferase (Ugcg), the first rate limiting step in the glucosylceramide biosynthesis pathway, was inhibited via chemical compounds and shRNA knockdown in vivo and in vitro. β-1,4-Galactosyltransferase (B4Galt) 5 and 6, enzymes that convert glucosylceramides into potentially inactive lactosylceramides, were subjected to shRNA knock down. Subsequently, (pre)adipocyte cell lines were tested in co-culture experiments with iNKT cells (IFNγ and IL4 secretion). Inhibition of Ugcg activity shows that it regulates presentation of a considerable fraction of lipid self-antigens in adipocytes. Furthermore, reduced expression levels of either B4Galt5 or -6, indicate that B4Galt5 is dominant in the production of cellular lactosylceramides, but that inhibition of either enzyme results in increased iNKT cell activation. Additionally, in vivo inhibition of Ugcg by the aminosugar AMP-DNM results in decreased iNKT cell effector function in adipose tissue. Inhibition of endogenous glucosylceramide production results in decreased iNKT cells activity and cytokine production, underscoring the role of this biosynthetic pathway in lipid self-antigen presentation by adipocytes.
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Affiliation(s)
- Maryam Rakhshandehroo
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Robert J van Eijkeren
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Tanit L Gabriel
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Colin de Haar
- Laboratory for Translational Immunology, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Sanne M W Gijzel
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Nicole Hamers
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Maria J Ferraz
- Leiden Institute of Chemistry, Department of Biochemistry, Leiden University, Leiden, the Netherlands
| | - Johannes M F G Aerts
- Leiden Institute of Chemistry, Department of Biochemistry, Leiden University, Leiden, the Netherlands
| | - Henk S Schipper
- Laboratory for Translational Immunology, University Medical Centre Utrecht, Utrecht, the Netherlands; Department of Pediatric Cardiology, Wilhelmina Children's Hospital, University Medical Center Utrecht, the Netherlands
| | - Marco van Eijk
- Leiden Institute of Chemistry, Department of Biochemistry, Leiden University, Leiden, the Netherlands
| | - Marianne Boes
- Laboratory for Translational Immunology, University Medical Centre Utrecht, Utrecht, the Netherlands; Department of Paediatric Immunology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Eric Kalkhoven
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands.
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Evers-van Gogh IJA, Oteng AB, Alex S, Hamers N, Catoire M, Stienstra R, Kalkhoven E, Kersten S. Muscle-specific inflammation induced by MCP-1 overexpression does not affect whole-body insulin sensitivity in mice. Diabetologia 2016; 59:624-33. [PMID: 26661101 PMCID: PMC4742493 DOI: 10.1007/s00125-015-3822-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/04/2015] [Indexed: 11/01/2022]
Abstract
AIMS/HYPOTHESIS Obesity is associated with a state of chronic low-grade inflammation that is believed to contribute to the development of skeletal muscle insulin resistance. However, the extent to which local and systemic elevation of cytokines, such as monocyte chemoattractant protein 1 (MCP-1), interferes with the action of insulin and promotes insulin resistance and glucose intolerance in muscle remains unclear. Here, we aim to investigate the effect of muscle-specific overexpression of MCP-1 on insulin sensitivity and glucose tolerance in lean and obese mice. METHODS We used Mck-Mcp-1 transgenic (Tg) mice characterised by muscle-specific overexpression of Mcp-1 (also known as Ccl2) and elevated plasma MCP-1 levels. Mice were fed either chow or high-fat diet for 10 weeks. Numerous metabolic variables were measured, including glucose and insulin tolerance tests, muscle insulin signalling and plasma NEFA, triacylglycerol, cholesterol, glucose and insulin. RESULTS Despite clearly promoting skeletal muscle inflammation, muscle-specific overexpression of Mcp-1 did not influence glucose tolerance or insulin sensitivity in either lean chow-fed or diet-induced obese mice. In addition, plasma NEFA, triacylglycerol, cholesterol, glucose and insulin were not affected by MCP-1 overexpression. Finally, in vivo insulin-induced Akt phosphorylation in skeletal muscle did not differ between Mcp-1-Tg and wild-type mice. CONCLUSIONS/INTERPRETATION We show that increased MCP-1 production in skeletal muscle and concomitant elevated MCP-1 levels in plasma promote inflammation in skeletal muscle but do not influence insulin signalling and have no effect on insulin resistance and glucose tolerance in lean and obese mice. Overall, our data argue against MCP-1 promoting insulin resistance in skeletal muscle and raise questions about the impact of inflammation on insulin sensitivity in muscle.
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Affiliation(s)
- Inkie J A Evers-van Gogh
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Antwi-Boasiako Oteng
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Sheril Alex
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Nicole Hamers
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Milene Catoire
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Rinke Stienstra
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Eric Kalkhoven
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands.
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Gao Y, Hamers N, Rakhshandehroo M, Berger R, Lough J, Kalkhoven E. Allele compensation in tip60+/- mice rescues white adipose tissue function in vivo. PLoS One 2014; 9:e98343. [PMID: 24870614 PMCID: PMC4037199 DOI: 10.1371/journal.pone.0098343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 05/01/2014] [Indexed: 01/14/2023] Open
Abstract
Adipose tissue is a key regulator of energy homestasis. The amount of adipose tissue is largely determined by adipocyte differentiation (adipogenesis), a process that is regulated by the concerted actions of multiple transcription factors and cofactors. Based on in vitro studies in murine 3T3-L1 preadipocytes and human primary preadipocytes, the transcriptional cofactor and acetyltransferase Tip60 was recently identified as an essential adipogenic factor. We therefore investigated the role of Tip60 on adipocyte differentiation and function, and possible consequences on energy homeostasis, in vivo. Because homozygous inactivation results in early embryonic lethality, Tip60+/− mice were used. Heterozygous inactivation of Tip60 had no effect on body weight, despite slightly higher food intake by Tip60+/− mice. No major effects of heterozygous inactivation of Tip60 were observed on adipose tissue and liver, and Tip60+/− displayed normal glucose tolerance, both on a low fat and a high fat diet. While Tip60 mRNA was reduced to 50% in adipose tissue, the protein levels were unaltered, suggesting compensation by the intact allele. These findings indicate that the in vivo role of Tip60 in adipocyte differentiation and function cannot be properly addressed in Tip60+/− mice, but requires the generation of adipose tissue-specific knock out animals or specific knock-in mice.
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Affiliation(s)
- Yuan Gao
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands
- Netherlands Metabolomics Center, Leiden, The Netherlands
| | - Nicole Hamers
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands
- Netherlands Metabolomics Center, Leiden, The Netherlands
| | - Maryam Rakhshandehroo
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Ruud Berger
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands
- Netherlands Metabolomics Center, Leiden, The Netherlands
| | - John Lough
- Department of Cell Biology, Neurobiology and Anatomy and the Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Eric Kalkhoven
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands
- Netherlands Metabolomics Center, Leiden, The Netherlands
- * E-mail:
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Schipper HS, Rakhshandehroo M, van de Graaf SFJ, Venken K, Koppen A, Stienstra R, Prop S, Meerding J, Hamers N, Besra G, Boon L, Nieuwenhuis EES, Elewaut D, Prakken B, Kersten S, Boes M, Kalkhoven E. Natural killer T cells in adipose tissue prevent insulin resistance. J Clin Invest 2012; 122:3343-54. [PMID: 22863618 DOI: 10.1172/jci62739] [Citation(s) in RCA: 161] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 07/05/2012] [Indexed: 12/12/2022] Open
Abstract
Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell-deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue-resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue-resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance.
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Affiliation(s)
- Henk S Schipper
- Department of Metabolic Diseases, University Medical Center Utrecht, Utrecht, the Netherlands
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Jeninga EH, de Vroede M, Hamers N, Breur JMPJ, Verhoeven-Duif NM, Berger R, Kalkhoven E. A Patient with Congenital Generalized Lipodystrophy Due To a Novel Mutation in BSCL2: Indications for Secondary Mitochondrial Dysfunction. JIMD Rep 2012; 4:47-54. [PMID: 23430896 PMCID: PMC3509903 DOI: 10.1007/8904_2011_86] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 08/19/2011] [Accepted: 08/22/2011] [Indexed: 03/24/2023] Open
Abstract
BACKGROUND Congenital generalized lipodystrophy (CGL) results from mutations in AGPAT2, encoding 1-acyl-glycerol-3-phosphate-acyltransferase 2 (CGL1; MIM 608594), BSCL2, encoding seipin (CGL2; MIM 269700), CAV1, encoding caveolin1 (CGL3; MIM 612526) or PTRF, encoding polymerase I and transcript release factor (CGL4; MIM 613327). This study aims to investigate the genotype/phenotype relationship and search for a possible pathogenic mechanism in a patient with CGL. DESIGN Case report. PATIENTS AND SETTING A 7-day-old child of consanguineous Turkish parents presented with a generalized loss of subcutaneous fat. He had a strikingly enlarged liver, high serum triglycerides, and hyperglycaemia, suggestive for CGL. RESULTS A novel homozygous mutation in the acceptor splice site of exon 5 of the BSCL2 gene was found in the genome of the proband. This mutation causes a complex RNA splicing defect and results in two different aberrant seipin proteins, which were normally expressed and localized to the endoplasmic reticulum like wild type protein. Analysis of the patient's urine showed intermittent elevations of citric acid intermediates and persistently high concentrations of ethylmalonic acid, suggestive of a disturbance of the mitochondrial respiratory chain. CONCLUSION Here we report abnormal urinary organic acid levels, indicative of mitochondrial dysfunction, in a patient with CGL resulting from a novel mutation in BSCL2. Our findings suggest for the first time an association between CGL and secondary mitochondrial dysfunction.
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Affiliation(s)
- Ellen H. Jeninga
- Department of Metabolic Diseases, UMC Utrecht, Room KE.03.139.2, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Netherlands Metabolomics Centre, Leiden, The Netherlands
- Department of Clinical Chemistry, Metabolic Unit, VU Academic Medical Center Amsterdam, Room PX 1-X-020, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Monique de Vroede
- Department of Pediatric Endocrinology, UMC Utrecht, Utrecht, The Netherlands
| | - Nicole Hamers
- Department of Metabolic Diseases, UMC Utrecht, Room KE.03.139.2, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Netherlands Metabolomics Centre, Leiden, The Netherlands
| | | | - Nanda M. Verhoeven-Duif
- Department of Metabolic Diseases, UMC Utrecht, Room KE.03.139.2, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Netherlands Metabolomics Centre, Leiden, The Netherlands
| | - Ruud Berger
- Department of Metabolic Diseases, UMC Utrecht, Room KE.03.139.2, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Netherlands Metabolomics Centre, Leiden, The Netherlands
| | - Eric Kalkhoven
- Department of Metabolic Diseases, UMC Utrecht, Room KE.03.139.2, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Netherlands Metabolomics Centre, Leiden, The Netherlands
- Department of Pediatric Immunology, UMC Utrecht, Utrecht, The Netherlands
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Visser ME, Kropman E, Kranendonk ME, Koppen A, Hamers N, Stroes ES, Kalkhoven E, Monajemi H. Characterisation of non-obese diabetic patients with marked insulin resistance identifies a novel familial partial lipodystrophy-associated PPARγ mutation (Y151C). Diabetologia 2011; 54:1639-44. [PMID: 21479595 PMCID: PMC3110271 DOI: 10.1007/s00125-011-2142-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 03/16/2011] [Indexed: 02/05/2023]
Abstract
AIMS/HYPOTHESIS Familial partial lipodystrophy (FPLD) is a rare metabolic disorder with clinical features that may not be readily recognised. As FPLD patients require a specific therapeutic approach, early identification is warranted. In the present study we aimed to identify cases of FPLD among non-obese patients with type 2 diabetes mellitus and marked insulin resistance. METHODS We searched the databases of three diabetic outpatient clinics for patients with marked insulin resistance, arbitrarily defined as the use of ≥100 U insulin/day, and BMI ≤ 27 kg/m(2). In all patients, metabolic variables and anthropomorphic measurements were evaluated and DNA was sequenced for mutations in the genes encoding lamin A/C (LMNA), peroxisome proliferator-activated receptor γ (PPARγ) and cell death-inducing DFFA-like effector c (CIDEC). RESULTS Out of 5,221 diabetic individuals, 24 patients fulfilled all criteria. Twelve patients were willing to participate, of whom five showed clinical features of lipodystrophy. In three of these patients the clinical diagnosis of FPLD was confirmed by the presence of mutations in LMNA or PPARG; one patient harboured a novel heterozygous mutation (Y151C) in PPARG. The Y151C mutant displayed impaired DNA-binding capacity and hence reduced transcriptional activity compared with wild-type PPARγ. Dominant-negative activity was absent. CONCLUSION/INTERPRETATION The combination of BMI ≤ 27 kg/m(2) and the use of >100 U insulin/day increases the chance of identifying lipodystrophy. Thus careful assessment of clinical features of FPLD should be considered in these patients, allowing earlier therapeutic interventions.
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Affiliation(s)
- M. E. Visser
- Department of Vascular Medicine, Academic Medical Centre, Amsterdam, The Netherlands
| | - E. Kropman
- Department of Vascular Medicine, Academic Medical Centre, Amsterdam, The Netherlands
| | - M. E. Kranendonk
- Department of Metabolic and Endocrine Diseases and Netherlands Metabolomics Centre, University Medical Centre, Utrecht, The Netherlands
| | - A. Koppen
- Department of Metabolic and Endocrine Diseases and Netherlands Metabolomics Centre, University Medical Centre, Utrecht, The Netherlands
| | - N. Hamers
- Department of Metabolic and Endocrine Diseases and Netherlands Metabolomics Centre, University Medical Centre, Utrecht, The Netherlands
| | - E. S. Stroes
- Department of Vascular Medicine, Academic Medical Centre, Amsterdam, The Netherlands
| | - E. Kalkhoven
- Department of Metabolic and Endocrine Diseases and Netherlands Metabolomics Centre, University Medical Centre, Utrecht, The Netherlands
- Department of Pediatric Immunology, University Medical Centre, Utrecht, The Netherlands
| | - H. Monajemi
- Department of Vascular Medicine, University Medical Centre, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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Jeninga EH, Bugge A, Nielsen R, Kersten S, Hamers N, Dani C, Wabitsch M, Berger R, Stunnenberg HG, Mandrup S, Kalkhoven E. Peroxisome proliferator-activated receptor gamma regulates expression of the anti-lipolytic G-protein-coupled receptor 81 (GPR81/Gpr81). J Biol Chem 2009; 284:26385-93. [PMID: 19633298 DOI: 10.1074/jbc.m109.040741] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The ligand-inducible nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) plays a key role in the differentiation, maintenance, and function of adipocytes and is the molecular target for the insulin-sensitizing thiazoledinediones (TZDs). Although a number of PPARgamma target genes that may contribute to the reduction of circulating free fatty acids after TZD treatment have been identified, the relevant PPARgamma target genes that may exert the anti-lipolytic effect of TZDs are unknown. Here we identified the anti-lipolytic human G-protein-coupled receptor 81 (GPR81), GPR109A, and the (human-specific) GPR109B genes as well as the mouse Gpr81 and Gpr109A genes as novel TZD-induced genes in mature adipocytes. GPR81/Gpr81 is a direct PPARgamma target gene, because mRNA expression of GPR81/Gpr81 (and GPR109A/Gpr109A) increased in mature human and murine adipocytes as well as in vivo in epididymal fat pads of mice upon rosiglitazone stimulation, whereas small interfering RNA-mediated knockdown of PPARgamma in differentiated 3T3-L1 adipocytes showed a significant decrease in Gpr81 protein expression. In addition, chromatin immunoprecipitation sequencing analysis in differentiated 3T3-L1 cells revealed a conserved PPAR:retinoid X receptor-binding site in the proximal promoter of the Gpr81 gene, which was proven to be functional by electromobility shift assay and reporter assays. Importantly, small interfering RNA-mediated knockdown of Gpr81 partly reversed the inhibitory effect of TZDs on lipolysis in 3T3-L1 adipocytes. The coordinated PPARgamma-mediated regulation of the GPR81/Gpr81 and GPR109A/Gpr109A genes (and GPR109B in humans) presents a novel mechanism by which TZDs may reduce circulating free fatty acid levels and perhaps ameliorate insulin resistance in obese patients.
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Affiliation(s)
- Ellen H Jeninga
- Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands
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van Beekum O, Brenkman AB, Grøntved L, Hamers N, van den Broek NJF, Berger R, Mandrup S, Kalkhoven E. The adipogenic acetyltransferase Tip60 targets activation function 1 of peroxisome proliferator-activated receptor gamma. Endocrinology 2008; 149:1840-9. [PMID: 18096664 DOI: 10.1210/en.2007-0977] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) plays a key role in the regulation of lipid and glucose metabolism in adipocytes, by regulating their differentiation, maintenance, and function. The transcriptional activity of PPARgamma is dictated by the set of proteins with which this nuclear receptor interacts under specific conditions. Here we identify the HIV-1 Tat-interacting protein 60 (Tip60) as a novel positive regulator of PPARgamma transcriptional activity. Using tandem mass spectrometry, we found that PPARgamma and the acetyltransferase Tip60 interact in cells, and through use of chimeric proteins, we established that coactivation by Tip60 critically depends on the N-terminal activation function 1 of PPARgamma, a domain involved in isotype-specific gene expression and adipogenesis. Chromatin immunoprecipitation experiments showed that the endogenous Tip60 protein is recruited to PPARgamma target genes in mature 3T3-L1 adipocytes but not in preadipocytes, indicating that Tip60 requires PPARgamma for its recruitment to PPARgamma target genes. Importantly, we show that in common with disruption of PPARgamma function, small interfering RNA-mediated reduction of Tip60 protein impairs differentiation of 3T3-L1 preadipocytes. Taken together, these findings qualify the acetyltransferase Tip60 as a novel adipogenic factor.
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Affiliation(s)
- Olivier van Beekum
- Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, Lundlaan 6, Utrecht, The Netherlands
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Jeninga EH, van Beekum O, van Dijk ADJ, Hamers N, Hendriks-Stegeman BI, Bonvin AMJJ, Berger R, Kalkhoven E. Impaired Peroxisome Proliferator-Activated Receptor γ Function through Mutation of a Conserved Salt Bridge (R425C) in Familial Partial Lipodystrophy. Mol Endocrinol 2007; 21:1049-65. [PMID: 17312272 DOI: 10.1210/me.2006-0485] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
AbstractThe nuclear receptor peroxisome proliferator-activated receptor (PPAR) γ plays a key role in the regulation of glucose and lipid metabolism in adipocytes by regulating their differentiation, maintenance, and function. A heterozygous mutation in the PPARG gene, which changes an arginine residue at position 425 into a cysteine (R425C), has been reported in a patient with familial partial lipodystrophy subtype 3 (FPLD3). The strong conservation of arginine 425 among nuclear receptors that heterodimerize with retinoic acid X receptor prompted us to investigate the functional consequences of the R425C mutation on PPARγ function. Here we show that this mutant displayed strongly reduced transcriptional activity compared with wild-type PPARγ, irrespective of cell type, promoter context, or ligand, whereas transrepression of nuclear factor-κB activity remained largely intact. Our data indicate that the reduced transcriptional activity of PPARγ R425C is not caused by impaired corepressor release, but due to reduced dimerization with retinoic acid X receptor α in combination with reduced ligand binding and subsequent coactivator binding. As a consequence of these molecular defects, the R425C mutant was less effective in inducing adipocyte differentiation. PPARγ R425C did not inhibit its wild-type counterpart in a dominant-negative manner, suggesting a haploinsufficiency mechanism in at least some FPLD3 patients. Using molecular dynamics simulations, substitution of R425 with cysteine is predicted to cause the formation of an alternative salt bridge. This structural change provides a likely explanation of how mutation of a single conserved residue in a patient with FPLD3 can disrupt the function of the adipogenic transcription factor PPARγ on multiple levels.
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Affiliation(s)
- Ellen H Jeninga
- Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, Room KE.03.139.2, Lundlaan 6, 3584 EA Utrecht, The Netherlands
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10
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van Buul-Offers SC, Smink JJ, Gresnigt R, Hamers N, Koedam J, Karperien M. Thyroid hormone, but not parathyroid hormone, partially restores glucocorticoid-induced growth retardation. Pediatr Nephrol 2005; 20:335-41. [PMID: 15688232 DOI: 10.1007/s00467-004-1690-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 09/01/2004] [Accepted: 09/14/2004] [Indexed: 11/25/2022]
Abstract
Growth retardation is a serious side effect of long-term glucocorticoid (GC) treatment. In order to prevent or diminish this deleterious effect, a combination therapy including growth hormone (GH), a stimulator of bone growth, is often recommended. Parathyroid hormone (PTH) and thyroid hormone (T(4)) are important hormonal regulators of bone growth, and might also be helpful anabolic agents for counteracting the negative effects of GCs. Therefore, we studied the interaction of GCs in combination with a single dose of either PTH or T(4) on GC-induced growth retardation. Dexamethasone (Dex) treatment of mice for four weeks induced a significant growth inhibition of body length and weight and weights of several organs. PTH or T(4) alone did not affect the normal growth pattern. However, T(4) could partially restore the Dex-induced growth inhibition, whereas PTH could not. Although PTH did not affect total body growth, it did affect the height of the proliferative zone, which could be counteracted by Dex. This contrasts with T(4) treatment alone or in combination with Dex, which both resulted in a disturbed morphology of the growth plate. IGF-I mRNA, one of the mediators of longitudinal bone growth, was present in proliferative and hypertrophic chondrocytes. However, its expression was not affected by any of the treatments. In conclusion, T(4) but not PTH can partially counteract the effects of Dex on general body growth, with possible implications for future treatments of GC-induced growth retardation. Additionally, both T(4) and PTH, alone or in combination with Dex, have differential effects on the morphology of the growth plate.
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Affiliation(s)
- Sylvia C van Buul-Offers
- Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, P.O. Box 85090, 3508 AB, Utrecht, The Netherlands.
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Van Hee P, Neels H, De Doncker M, Vrydags N, Schatteman K, Uyttenbroeck W, Hamers N, Himpe D, Lambert W. Analysis of γ-hydroxybutyric acid, DL-lactic acid, glycolic acid, ethylene glycol and other glycols in body fluids by a direct injection gas chromatography-mass spectrometry assay for wide use. ACTA ACUST UNITED AC 2004; 42:1341-5. [PMID: 15576294 DOI: 10.1515/cclm.2004.252] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractAnalysis of blood of severely intoxicated patients always requires prompt investigation. Diagnosis of intoxication with ethylene glycol, γ-hydroxybutyric acid or D-lactic acid takes hours, since several different procedures are required. Rapid derivatization of the common hydroxyl function may resolve this analytical problem.Here we describe a fast method for the simultaneous measurement of ethylene glycol, glycolic acid, γ-hydroxybutyric acid and racemic lactic acid. Only 20 µl of serum, plasma or urine are required for immediate derivatization at 70°C with 750 µl of bis-N,O-trimethylsilyl trifluoroacetamide after adding 20 µl of internal standard solution (1,3-propylene glycol) and 20 µl of the catalyst dimethylformamide. After centrifugation an aliquot is transferred to a gas chromatographic system and analyzed with electron-impact mass spectrometry in selective ion monitoring mode.The derivatized acids and ethylene glycol are well separated and detected with a limit of detection ranging from 0.12 mg/l for ethylene glycol to 0.95 mg/l for γ-hydroxybutyric acid, while the limit of quantification ranged from 0.4 mg/l for ethylene glycol to 3.15 mg/l for γ-hydroxybutyric acid. The method is linear from 0.5 to 1800 mg/l blood for ethylene glycol, from 0.7 to 1200 mg/l for lactic acid, from 1.2 to 1800 mg/l for glycolic acid, and from 3.2 to 200 mg/l for γ-hydroxybutyric acid, with analytical recoveries, accuracy, day-to-day and within-day precision well within the required limits. Total analysis time with one calibrator was 30 min, derivatization time included.This method is very suitable for emergency toxicology, since several toxic substances can be quantified simultaneously in a fast and sensitive manner.
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Affiliation(s)
- Paul Van Hee
- Laboratory of Biochemistry and Toxicology, Ziekenhuis Netwerk Antwerpen Stuivenberg, Antwerp, Belgium
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Smink JJ, Buchholz IM, Hamers N, van Tilburg CM, Christis C, Sakkers RJB, de Meer K, van Buul-Offers SC, Koedam JA. Short-term glucocorticoid treatment of piglets causes changes in growth plate morphology and angiogenesis. Osteoarthritis Cartilage 2003; 11:864-71. [PMID: 14629962 DOI: 10.1016/s1063-4584(03)00187-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Glucocorticoid treatment of children often leads to growth retardation, and the precise target(s) in the growth plate responsible for this effect are unknown. Angiogenesis is an important part of the endochondral ossification process, and VEGF expressed in the growth plate is essential for proper angiogenesis to occur. Since glucocorticoid treatment down-regulates VEGF expression in cultured chondrocytes, we hypothesized that in vivo glucocorticoid treatment could result in VEGF down-regulation in the growth plate and disturbed angiogenesis, thus contributing to the growth retardation. DESIGN We treated 6-week-old prepubertal piglets (10 kg) for 5 days with prednisolone (50 mg/day). Tibial growth plate sections were studied for apoptosis and the expression of VEGF protein and mRNA and MMP-9 protein. Capillaries in the metaphysis were visualized by CD31 immunostaining. Growth plate morphology (width of various zones) was determined by interactive measurements on hematoxylin/eosin stained sections and apoptotic cells were detected by TUNEL assay. RESULTS In the prednisolone-treated animals, the total width of the growth plate decreased to 81% of controls (P<0.02), which was explained by a decrease of the width of the proliferative zone to 73% (P<0.05). The treatment had no effect on the orderly organization of the chondrocyte columns. In the growth plates of control animals, apoptosis was shown in 5.8% of the hypertrophic chondrocytes and was limited to the terminal hypertrophic chondrocytes. In prednisolone-treated animals, 40.5% of the hypertrophic chondrocytes was apoptotic (P<0.02), with apoptotic chondrocytes also appearing higher in the hypertrophic zone. We observed fewer capillaries and loss of their parallel organization in the metaphysis in the prednisolone-treated animals. The capillaries were shorter and chaotic in appearance. In contrast to controls, in prednisolone-treated animals VEGF mRNA and protein could not be detected in the hypertrophic zone of the growth plate. Trabecular bone length in the primary spongiosa was also diminished by the treatment. No changes were observed in the expression pattern of MMP-9, a matrix metalloproteinase, which is also important for angiogenesis and bone formation. CONCLUSIONS These results indicate that short-term glucocorticoid treatment of growing piglets severely disturbs the width of the growth plate, apoptosis of chondrocytes, VEGF expression by hypertrophic chondrocytes, the normal invasion of blood vessels from the metaphysis to the growth plate and bone formation at the chondro-osseous junction. These effects could alter the dynamics of endochondral ossification and thus contribute to glucocorticoid-induced growth retardation.
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Affiliation(s)
- J J Smink
- Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, Utrecht, The Netherlands
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13
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Smink JJ, Gresnigt MG, Hamers N, Koedam JA, Berger R, Van Buul-Offers SC. Short-term glucocorticoid treatment of prepubertal mice decreases growth and IGF-I expression in the growth plate. J Endocrinol 2003; 177:381-8. [PMID: 12773118 DOI: 10.1677/joe.0.1770381] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The insulin-like growth factor (IGF) system is an important mediator of postnatal longitudinal growth, and the growth inhibiting effects of glucocorticoid (GC) treatment are suggested to be due to impaired action of the IGF system. However, the precise changes of the IGFs and the IGF-binding proteins (IGFBPs) in the growth plate, occurring upon short-term GC treatment have not been characterized. Prepubertal mice treated daily with dexamethasone (DXM) for 7 days, showed significant growth inhibition of total body length and weight and weight of the liver, thymus and spleen, whereas the weight of the kidneys was not affected. Analysis of the tibial growth plate showed that the total growth plate width significantly decreased to 84.5% of control values, caused by a significant decrease in the proliferative zone. The number of proliferating cell nuclear antigen (PCNA)-positive chondrocytes in the proliferative zone decreased significantly (to 40%) and TUNEL staining showed a significant 1.6-fold increase in apoptotic hypertrophic chondrocytes. In the growth plates, both IGF-I and IGF-II, as well as IGFBP-2 mRNAs were detected, mainly in the proliferative and prehypertrophic zones. DXM treatment significantly decreased the number of chondrocytes expressing IGF-I, whereas the number of chondrocytes expressing IGF-II and IGFBP-2 were not affected. The decrease in IGF-I expression in the growth plate indicates that GC treatment affects IGF-I at the local level of the growth plate, which could contribute to the GC-induced growth retardation.
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Affiliation(s)
- J J Smink
- Department of Metabolic and Endocrine Diseases, University Medical Centre Utrecht, Utrecht, The Netherlands
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14
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Peeters-Scholte C, Koster J, van den Tweel E, Blomgren K, Hamers N, Zhu C, van Buul-Offers S, Hagberg H, van Bel F, Heijnen C, Groenendaal F. Effects of selective nitric oxide synthase inhibition on IGF-1, caspases and cytokines in a newborn piglet model of perinatal hypoxia-ischaemia. Dev Neurosci 2003; 24:396-404. [PMID: 12640178 DOI: 10.1159/000069045] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2002] [Accepted: 09/24/2002] [Indexed: 11/19/2022] Open
Abstract
Selective inhibition of neuronal and inducible nitric oxide synthase (NOS) with 2-iminobiotin previously showed a reduction in brain cell injury. In the present study, we investigated the effects of 2-iminobiotin treatment on insulin-like growth factor-1 (IGF-1) expression, caspase activity and cytokine expression in a newborn piglet model of perinatal hypoxia-ischaemia. Newborn piglets were subjected to 1 h of hypoxia-ischaemia and were treated intravenously with vehicle or 2-iminobiotin. Vehicle-treated piglets showed reduced IGF-1 mRNA expression and increased caspase-3 activity and DNA fragmentation. 2-Iminobiotin treatment, administered immediately upon reperfusion, prevented these observations. No differences in caspase-8 and -9 activity and cytokine [interleukin (IL)-1alpha/beta, IL-6, tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta] mRNA expression were demonstrated between vehicle- and 2-iminobiotin-treated piglets at 24 h following hypoxia-ischaemia. IGF-1 mRNA correlated inversely with caspase-3 and transferase-mediated dUTP-biotin in situ nick end labelling score in the cortex, but positively with caspase-8. Cytokine mRNA did not correlate with IGF-1 mRNA, caspase-3 activity or DNA fragmentation. The present results indicate that the previously demonstrated neuroprotective effect of 2-iminobiotin treatment after perinatal hypoxia-ischaemia coincided with a preservation of the endogenous IGF-1 production and reduced caspase-3 activity, but not with a significant decrease in cytokine production.
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Affiliation(s)
- Cacha Peeters-Scholte
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
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Abstract
In the Belgian national external quality assessment scheme, we observed significantly lowered recoveries for urate in the group of Beckman Synchron users in comparison with the overall median values of the uricase/peroxidase colorimetric methods. These effects were linked to control sera of some manufacturers and we could demonstrate that these sera contained large amounts of pyridoxal-5-phosphate (PLP) as activator for transaminases. By spiking normal human serum with increasing PLP concentrations from 62.5 to 1000 mumol l-1, we observed a decrease in the urate recovery from 125 mumol l-1 (-11%). At 1000 mumol l-1 PLP, only 40% of the urate concentration was measured. An explanation for this effect was found in the polychromatic corrections of the Beckman Sychron system only applied with the Beckman urate method. This study demonstrates that EQAS organizers must carefully distinguish in their peer groups, not only the analytical principle and the measurement equipment, but also the reagent origin. Finally, the use of EQA control sera without PLP addition is strongly recommended if these sera are intended to be used as accuracy controls in EQA schemes including Beckman Synchron users.
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Affiliation(s)
- J C Libeer
- Department of Clinical Pathology, Institute of Hygiene and Epidemiology, Brussels, Belgium
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Abstract
In assay of serum proteins by use of the biuret reaction, dextran can cause turbidity by formation of an insoluble complex of dextran with copper and tartrate (or EDTA) in strongly alkaline solution. Whether or not the turbidity occurs depends on the tartrate concentration: turbidity is maximal at about 10 g/L, absent at 20 g/L or more, and only slight and delayed at 4 g/L. Two biuret reagents, containing respectively 5.6 and 22.5 g of tartrate per liter, obviate the interference, but the former is suitable only when a short (5 min) incubation is used. Both reagents show linear calibration curves and yield virtually identical results.
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Affiliation(s)
- Joris R Delanghe
- Department of Clinical Chemistry, University Hospital Ghent, Ghent, Belgium.
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