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Dideriksen K, Reitelseder S, Malmgaard-Clausen NM, Bechshoeft R, Petersen RK, Mikkelsen UR, Holm L. No effect of anti-inflammatory medication on postprandial and postexercise muscle protein synthesis in elderly men with slightly elevated systemic inflammation. Exp Gerontol 2016; 83:120-9. [PMID: 27497779 DOI: 10.1016/j.exger.2016.07.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [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: 02/17/2016] [Revised: 06/27/2016] [Accepted: 07/29/2016] [Indexed: 01/31/2023]
Abstract
BACKGROUND Based on circulating C-reactive protein (CRP) levels, some individuals develop slightly increased inflammation as they age. In elderly inflamed rats, the muscle response to protein feeding is impaired, whereas it can be maintained by treatment with non-steroidal anti-inflammatory drugs (NSAIDs). It is unknown whether this applies to elderly humans with increased inflammation. Thus, the muscle response to whey protein bolus ingestion with and without acute resistance exercise was compared between healthy elderly individuals and elderly individuals with slightly increased inflammation±NSAID treatment. METHODS Twenty-four elderly men (>60years) were recruited. Of those, 14 displayed a slightly increased systemic inflammation (CRP>2mg/l) and were randomly assigned to NSAID (Ibuprofen 1800mg/day) or placebo treatment for 1week. The remaining 10 elderly individuals served as healthy controls (CRP<1mg/l). The muscle protein synthetic response was measured as the fractional synthetic rate (FSR) and p70S6K phosphorylation-to-total protein ratio. RESULTS The basal myofibrillar FSR and the myofibrillar FSR responses to whey protein bolus ingestion with and without acute resistance exercise were maintained in inflamed elderly compared to healthy controls (p>0.05) and so was p70S6K phosphorylation. Moreover, NSAID treatment did not significantly improve the myofibrillar and connective tissue FSR responses or reduce the plasma CRP level in inflamed, elderly individuals (p>0.05). CONCLUSION A slight increase in systemic inflammation does not affect the basal myofibrillar FSR or the myofibrillar FSR responses, which suggests that elderly individuals with slightly increased inflammation can benefit from protein ingestion and resistance exercise to stimulate muscle protein anabolism. Moreover, the NSAID treatment did not significantly affect the myofibrillar or connective tissue FSR responses to protein ingestion and acute resistance exercise.
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Affiliation(s)
- K Dideriksen
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - S Reitelseder
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Institute of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - N M Malmgaard-Clausen
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - R Bechshoeft
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Institute of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - R K Petersen
- Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - U R Mikkelsen
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - L Holm
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Institute of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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2
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Dixit VA, Rathi PC, Bhagat S, Gohlke H, Petersen RK, Kristiansen K, Chakraborti AK, Bharatam PV. Design and synthesis of novel Y-shaped barbituric acid derivatives as PPARγ activators. Eur J Med Chem 2016; 108:423-435. [DOI: 10.1016/j.ejmech.2015.11.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 10/22/2022]
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3
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Hallenborg P, Petersen RK, Kouskoumvekaki I, Newman JW, Madsen L, Kristiansen K. The elusive endogenous adipogenic PPARγ agonists: Lining up the suspects. Prog Lipid Res 2016; 61:149-62. [DOI: 10.1016/j.plipres.2015.11.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 02/07/2023]
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4
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Kopp TI, Lundqvist J, Petersen RK, Oskarsson A, Kristiansen K, Nellemann C, Vogel U. In vitro screening of inhibition of PPAR-γ activity as a first step in identification of potential breast carcinogens. Hum Exp Toxicol 2015; 34:1106-18. [DOI: 10.1177/0960327115569811] [Citation(s) in RCA: 5] [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] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Alcohol consumption and increased estrogen levels are major risk factors for breast cancer, and peroxisome proliferator-activated receptor γ (PPAR-γ) plays an important role in alcohol-induced breast cancer. PPAR-γ activity is inhibited by ethanol, leading to increased aromatase activity and estrogen biosynthesis ultimately leading to breast cancer. If other organic solvents inhibit PPAR-γ activity, they should also lead to increased oestrogen biosynthesis and thus be potential breast carcinogens. Ten commonly used hydrophilic organic solvents were first tested in a cell-based screening assay for inhibitory effects on PPAR-γ transactivation. The chemicals shown to inhibit PPAR-γ were tested with vectors encoding PPAR-γ with deleted AB domains and only the ligand-binding domain to rule out unspecific toxicity. Next, the effects on biosynthesis of estradiol, testosterone and oestrone sulphate were measured in the H295R steroidogenesis assay after incubation with the chemicals. Ethylene glycol, ethyl acetate, and dimethyl sulphoxide inhibited PPAR-γ transactivation in a dose-dependent manner. The inhibitory effect on PPAR-γ was specific for PPAR-γ since the AB domain of PPAR-γ was required for the inhibitory effect. In the second step, ethylene glycol significantly increased production of oestradiol by 19% ( p < 0.05) and ethyl acetate inhibited production of testosterone ( p < 0.05). We here show that screening of 10 commonly used organic solvents for the ability to inhibit PPAR-γ transactivation followed by a well-established steroidogenesis assay for production of sex hormones in exposed H295 R cells may provide a screening tool for potential breast carcinogens. This initial screening thus identified ethylene glycol and possibly ethyl acetate as potential breast carcinogens.
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Affiliation(s)
- TI Kopp
- National Food Institute, Technical University of Denmark, Søborg, Denmark
| | - J Lundqvist
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Denmark
| | - RK Petersen
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - A Oskarsson
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Denmark
| | - K Kristiansen
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - C Nellemann
- National Food Institute, Technical University of Denmark, Søborg, Denmark
| | - U Vogel
- National Research Centre for the Working Environment, Copenhagen Ø, Denmark
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5
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Kotowska D, El-Houri RB, Borkowski K, Petersen RK, Fretté XC, Wolber G, Grevsen K, Christensen KB, Christensen LP, Kristiansen K. Isomeric C12-alkamides from the roots of Echinacea purpurea improve basal and insulin-dependent glucose uptake in 3T3-L1 adipocytes. Planta Med 2014; 80:1712-1720. [PMID: 25371981 DOI: 10.1055/s-0034-1383252] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Echinacea purpurea has been used in traditional medicine as a remedy for the treatment and prevention of upper respiratory tract infections and the common cold. Recent investigations have indicated that E. purpurea also has an effect on insulin resistance. A dichloromethane extract of E. purpurea roots was found to enhance glucose uptake in adipocytes and to activate peroxisome proliferator-activated receptor γ. The purpose of the present study was to identify the bioactive compounds responsible for the potential antidiabetic effect of the dichloromethane extract using a bioassay-guided fractionation approach. Basal and insulin-dependent glucose uptake in 3T3-L1 adipocytes were used to assess the bioactivity of extract, fractions and isolated metabolites. A peroxisome proliferator-activated receptor γ transactivation assay was used to determine the peroxisome proliferator-activated receptor γ activating properties of the extract, active fractions and isolated metabolites. Two novel isomeric dodeca-2E,4E,8Z,10E/Z-tetraenoic acid 2-methylbutylamides together with two known C12-alkamides and α-linolenic acid were isolated from the active fractions. The isomeric C12-alkamides were found to activate peroxisome proliferator-activated receptor γ, to increase basal and insulin-dependent glucose uptake in adipocytes in a dose-dependent manner, and to exhibit characteristics of a peroxisome proliferator-activated receptor γ partial agonist.
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Affiliation(s)
- Dorota Kotowska
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rime B El-Houri
- Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense, Denmark
| | - Kamil Borkowski
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus K Petersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Xavier C Fretté
- Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense, Denmark
| | - Gerhard Wolber
- Computer-Aided Drug Design, Institute of Pharmacy, Medicinal and Pharmaceutical Chemistry, Freie Universität Berlin, Berlin, Germany
| | - Kai Grevsen
- Department of Food Science, Aarhus University, Aarslev, Denmark
| | - Kathrine B Christensen
- Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense, Denmark
| | - Lars P Christensen
- Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense, Denmark
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6
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Petersen RK, Hess S, Alavi A, Høilund-Carlsen PF. Clinical impact of FDG-PET/CT on colorectal cancer staging and treatment strategy. Am J Nucl Med Mol Imaging 2014; 4:471-482. [PMID: 25143865 PMCID: PMC4138141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 07/15/2014] [Indexed: 06/03/2023]
Abstract
FDG-PET/CT is rarely used for initial staging of patients with colorectal cancer (CRC). Surgical resection of primary tumor and isolated metastases may result in long-term survival or presumed cure, whereas disseminated disease contraindicates operation. We analyzed a retrospective material to elucidate the potential value of FDG-PET/CT for staging of CRC. Data were retrieved from 67 consecutive patients (24-84 years) with histopathologically proven CRC who had undergone FDG-PET/CT in addition to conventional imaging for initial staging. Treatment plans before and after FDG-PET/CT were compared and patients divided as follows: (A) Patients with a change in therapy following FDG-PET/CT and (B) Patients without a change following FDG-PET/CT. Sixty-two patients had colon and five had rectal cancer. Of these, 20 (30%; CI 20.2-41.7) belonged to group A, whereas 47 (70%; CI 58.3-79.8) fell in group B. In conclusion, FDG-PET/CT changed treatment plan in 30% of cases. In ⅓ of these there was either a change from intended curative to palliative therapy or vice versa, while in the remaining ⅔ the pattern was more mixed. Thus, even in a retrospective routine material there were substantial changes in management strategy following FDG-PET/CT for staging in CRC.
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Affiliation(s)
| | - Søren Hess
- Department of Nuclear Medicine, Odense University HospitalDenmark
| | - Abass Alavi
- Division of Nuclear Medicine, University of Pennsylvania School of Medicine, Hospital of The University of PennsylvaniaPhiladelphia, PA, USA
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Kouskoumvekaki I, Petersen RK, Fratev F, Taboureau O, Nielsen TE, Oprea TI, Sonne SB, Flindt EN, Jónsdóttir SÓ, Kristiansen K. Discovery of a Novel Selective PPARγ Ligand with Partial Agonist Binding Properties by Integrated in Silico/in Vitro Work Flow. J Chem Inf Model 2013; 53:923-37. [DOI: 10.1021/ci3006148] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Irene Kouskoumvekaki
- Center for Biological Sequence
Analysis, Department of Systems Biology, Technical University of Denmark, DK-2800
Kgs. Lyngby, Denmark
| | - Rasmus K. Petersen
- BioLigands, Science Park, 5230, Odense, Denmark
- Department
of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen, Denmark
| | - Filip Fratev
- Center for Biological Sequence
Analysis, Department of Systems Biology, Technical University of Denmark, DK-2800
Kgs. Lyngby, Denmark
- Micar 21 Ltd., 34B Persenk Str., 1407, Sofia, Bulgaria
| | - Olivier Taboureau
- Center for Biological Sequence
Analysis, Department of Systems Biology, Technical University of Denmark, DK-2800
Kgs. Lyngby, Denmark
- UMR-S973, MTi, University Paris Diderot, F-75013 Paris, France
| | - Thomas E. Nielsen
- Department
of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
- Singapore Centre on Environmental
Life Sciences Engineering, Nanyang Technological University, Singapore 637551
| | - Tudor I. Oprea
- Center for Biological Sequence
Analysis, Department of Systems Biology, Technical University of Denmark, DK-2800
Kgs. Lyngby, Denmark
- Translational
Informatics Division, Department of Internal
Medicine, MSC09 5025, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131,
United States
| | - Si B. Sonne
- Department
of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen, Denmark
| | - Esben N. Flindt
- BioLigands, Science Park, 5230, Odense, Denmark
- Department
of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen, Denmark
| | - Svava Ósk Jónsdóttir
- Center for Biological Sequence
Analysis, Department of Systems Biology, Technical University of Denmark, DK-2800
Kgs. Lyngby, Denmark
- Department
of Toxicology and Risk Assessment, National Food Institute, Technical University of Denmark, Mørkhøj
Bygade 19, DK-2860 Søborg, Denmark
| | - Karsten Kristiansen
- Department
of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200, Copenhagen, Denmark
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8
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Hao Q, Lillefosse HH, Fjaere E, Myrmel LS, Midtbø LK, Jarlsby RH, Ma T, Jia B, Petersen RK, Sonne SB, Chwalibog A, Frøyland L, Liaset B, Kristiansen K, Madsen L. High-glycemic index carbohydrates abrogate the antiobesity effect of fish oil in mice. Am J Physiol Endocrinol Metab 2012; 302:E1097-112. [PMID: 22338077 DOI: 10.1152/ajpendo.00524.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [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: 01/14/2023]
Abstract
Fish oil rich in n-3 polyunsaturated fatty acids is known to attenuate diet-induced obesity and adipose tissue inflammation in rodents. Here we aimed to investigate whether different carbohydrate sources modulated the antiobesity effects of fish oil. By feeding C57BL/6J mice isocaloric high-fat diets enriched with fish oil for 6 wk, we show that increasing amounts of sucrose in the diets dose-dependently increased energy efficiency and white adipose tissue (WAT) mass. Mice receiving fructose had about 50% less WAT mass than mice fed a high fish oil diet supplemented with either glucose or sucrose, indicating that the glucose moiety of sucrose was responsible for the obesity-promoting effect of sucrose. To investigate whether the obesogenic effect of sucrose and glucose was related to stimulation of insulin secretion, we combined fish oil with high and low glycemic index (GI) starches. Mice receiving the fish oil diet containing the low-GI starch had significantly less WAT than mice fed high-GI starch. Moreover, inhibition of insulin secretion by administration of nifedipine significantly reduced WAT mass in mice fed a high-fish oil diet in combination with sucrose. Our data show that the macronutrient composition of the diet modulates the effects of fish oil. Fish oil combined with sucrose, glucose, or high-GI starch promotes obesity, and the reported anti-inflammatory actions of fish oil are abrogated. In conclusion, our data indicate that glycemic control of insulin secretion modulates metabolic effects of fish oil by demonstrating that high-GI carbohydrates attenuate the antiobesity effects of fish oil.
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Affiliation(s)
- Qin Hao
- Department of Biology, University of Copenhagen, Denmark
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9
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Hallenborg P, Feddersen S, Francoz S, Murano I, Sundekilde U, Petersen RK, Akimov V, Olson MV, Lozano G, Cinti S, Gjertsen BT, Madsen L, Marine JC, Blagoev B, Kristiansen K. Mdm2 controls CREB-dependent transactivation and initiation of adipocyte differentiation. Cell Death Differ 2012; 19:1381-9. [PMID: 22388350 DOI: 10.1038/cdd.2012.15] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The role of the E3 ubiquitin ligase murine double minute 2 (Mdm2) in regulating the stability of the p53 tumor suppressor is well documented. By contrast, relatively little is known about p53-independent activities of Mdm2 and the role of Mdm2 in cellular differentiation. Here we report a novel role for Mdm2 in the initiation of adipocyte differentiation that is independent of its ability to regulate p53. We show that Mdm2 is required for cAMP-mediated induction of CCAAT/enhancer-binding protein δ (C/EBPδ) expression by facilitating recruitment of the cAMP regulatory element-binding protein (CREB) coactivator, CREB-regulated transcription coactivator (Crtc2)/TORC2, to the c/ebpδ promoter. Our findings reveal an unexpected role for Mdm2 in the regulation of CREB-dependent transactivation during the initiation of adipogenesis. As Mdm2 is able to promote adipogenesis in the myoblast cell line C2C12, it is conceivable that Mdm2 acts as a switch in cell fate determination.
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Affiliation(s)
- P Hallenborg
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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Christensen KB, Jørgensen M, Kotowska D, Petersen RK, Kristiansen K, Christensen LP. Activation of the nuclear receptor PPARγ by metabolites isolated from sage (Salvia officinalis L.). J Ethnopharmacol 2010; 132:127-133. [PMID: 20696231 DOI: 10.1016/j.jep.2010.07.054] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 07/20/2010] [Accepted: 07/30/2010] [Indexed: 05/29/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Salvia officinalis has been used as a traditional remedy against diabetes in many countries and its glucose-lowering effects have been demonstrated in animal studies. The active compounds and their possible mode of action are still unknown although it has been suggested that diterpenes may be responsible for the anti-diabetic effect of Salvia officinalis. AIM OF THE STUDY To investigate whether the reported anti-diabetic effects of Salvia officinalis are related to activation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)γ and to identify the bioactive constituents. MATERIALS AND METHODS From a dichloromethane extract of Salvia officinalis able to activate PPARγ several major metabolites were isolated by chromatographic techniques. To assess bioactivity of the isolated metabolites a PPARγ transactivation assay was used. RESULTS Eight diterpenes were isolated and identified including a new abietane diterpene being the epirosmanol ester of 12-O-methyl carnosic acid and 20-hydroxyferruginol, which was isolated from Salvia officinalis for the first time, as well as viridiflorol, oleanolic acid, and α-linolenic acid. 12-O-methyl carnosic acid and α-linolenic acid were able to significantly activate PPARγ whereas the remaining metabolites were either unable to activate PPARγ or yielded insignificant activation. CONCLUSIONS Selected metabolites from Salvia officinalis were able to activate PPARγ and hence, the anti-diabetic activity of this plant could in part be mediated through this nuclear receptor.
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Affiliation(s)
- K B Christensen
- Institute of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Niels Bohrs Allé 1, DK-5230 Odense M, Denmark.
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Christensen KB, Petersen RK, Kristiansen K, Christensen LP. Identification of bioactive compounds from flowers of black elder (Sambucus nigra L.) that activate the human peroxisome proliferator-activated receptor (PPAR) gamma. Phytother Res 2010; 24 Suppl 2:S129-32. [PMID: 20222152 DOI: 10.1002/ptr.3005] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Obesity is one of the predisposing factors for the development of overt Type 2 diabetes (T2D). T2D is caused by a combination of insulin resistance and beta-cell failure and can be treated with insulin sensitizing drugs that target the nuclear receptor peroxisome proliferator-activated receptor (PPAR) gamma. Extracts of elderflowers (Sambucus nigra) have been found to activate PPARgamma and to stimulate insulin-dependent glucose uptake suggesting that they have a potential use in the prevention and/or treatment of insulin resistance. Bioassay-guided chromatographic fractionation of a methanol extract of elderflowers resulted in the identification of two well-known PPARgamma agonists; alpha-linolenic acid and linoleic acid as well as the flavanone naringenin. Naringenin was found to activate PPARgamma without stimulating adipocyte differentiation. However, the bioactivities of these three metabolites were not able to fully account for the observed PPARgamma activation of the crude elderflower extracts and further studies are needed to determine whether this is due synergistic effects and/or other ligand-independent mechanisms. Elderflower metabolites such as quercetin-3-O-rutinoside, quercetin-3-O-glucoside, kaempferol-3-O-rutinoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and 5-O-caffeoylquinic acid were unable to activate PPARgamma. These findings suggest that flavonoid glycosides cannot activate PPARgamma, whereas some of their aglycones are potential agonists of PPARgamma.
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Madsen L, Pedersen LM, Lillefosse HH, Fjære E, Bronstad I, Hao Q, Petersen RK, Hallenborg P, Ma T, De Matteis R, Araujo P, Mercader J, Bonet ML, Hansen JB, Cannon B, Nedergaard J, Wang J, Cinti S, Voshol P, Døskeland SO, Kristiansen K. UCP1 induction during recruitment of brown adipocytes in white adipose tissue is dependent on cyclooxygenase activity. PLoS One 2010; 5:e11391. [PMID: 20613988 PMCID: PMC2894971 DOI: 10.1371/journal.pone.0011391] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 05/30/2010] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The uncoupling protein 1 (UCP1) is a hallmark of brown adipocytes and pivotal for cold- and diet-induced thermogenesis. METHODOLOGY/PRINCIPAL FINDINGS Here we report that cyclooxygenase (COX) activity and prostaglandin E(2) (PGE(2)) are crucially involved in induction of UCP1 expression in inguinal white adipocytes, but not in classic interscapular brown adipocytes. Cold-induced expression of UCP1 in inguinal white adipocytes was repressed in COX2 knockout (KO) mice and by administration of the COX inhibitor indomethacin in wild-type mice. Indomethacin repressed beta-adrenergic induction of UCP1 expression in primary inguinal adipocytes. The use of PGE(2) receptor antagonists implicated EP(4) as a main PGE(2) receptor, and injection of the stable PGE(2) analog (EP(3/4) agonist) 16,16 dm PGE(2) induced UCP1 expression in inguinal white adipose tissue. Inhibition of COX activity attenuated diet-induced UCP1 expression and increased energy efficiency and adipose tissue mass in obesity-resistant mice kept at thermoneutrality. CONCLUSIONS/SIGNIFICANCE Our findings provide evidence that induction of UCP1 expression in white adipose tissue, but not in classic interscapular brown adipose tissue is dependent on cyclooxygenase activity. Our results indicate that cyclooxygenase-dependent induction of UCP1 expression in white adipose tissues is important for diet-induced thermogenesis providing support for a surprising role of COX activity in the control of energy balance and obesity development.
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Affiliation(s)
- Lise Madsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - Lone M. Pedersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Haldis Haukaas Lillefosse
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - Even Fjære
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | | | - Qin Hao
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Philip Hallenborg
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Tao Ma
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rita De Matteis
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - Pedro Araujo
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - Josep Mercader
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, and CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain
| | - M. Luisa Bonet
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, and CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain
| | - Jacob B. Hansen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Barbara Cannon
- The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jan Nedergaard
- The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jun Wang
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- BGI-Shenzhen, Shenzhen, China
| | - Saverio Cinti
- Department of Molecular Pathology and Innovative Therapies, University of Ancona, Ancona, Italy
| | - Peter Voshol
- Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom
| | | | - Karsten Kristiansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- BGI-Shenzhen, Shenzhen, China
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13
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Wein S, Behm N, Petersen RK, Kristiansen K, Wolffram S. Quercetin enhances adiponectin secretion by a PPAR-gamma independent mechanism. Eur J Pharm Sci 2010; 41:16-22. [PMID: 20580672 DOI: 10.1016/j.ejps.2010.05.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/30/2010] [Accepted: 05/10/2010] [Indexed: 12/22/2022]
Abstract
To study possible insulin sensitizing, anti-inflammatory and anti-oxidative effects of the flavonol quercetin, rats were fed a high-fat diet (19%, w/w) with (HFQ) or without (HF) 0.03% quercetin or a flavonoid-poor low-fat (5%, w/w) maintenance diet (LF) over 4 weeks. Body weight was measured weekly, and plasma concentrations of adiponectin, leptin, insulin, glucose, triacylglycerols, total cholesterol, as well as of markers of inflammation and oxidative stress were measured (12h fasted) at the end of the feeding period. Adiponectin and peroxisome-proliferator-activated-receptor (PPAR)-gamma mRNA were measured in adipose tissue (WAT) by real-time RT-PCR. PPAR-gamma transactivation was investigated by means of a reporter gene assay. HF feeding resulted in elevated fasted plasma glucose concentrations, while HFQ did not differ from LF feeding. In the HFQ group plasma concentrations and WAT mRNA levels of adiponectin were elevated compared with the HF group, however, PPAR-gamma mRNA concentration in WAT was decreased (HFQ vs. HF). Compared to both other groups quercetin feeding significantly reduced oxidative stress, measured by plasma 8-iso-PGF(2alpha), while body weight gain, body composition and plasma leptin levels were not affected. Neither quercetin nor its metabolites induced PPAR-gamma-mediated transactivation in vitro. Adiponectin stimulating effects of quercetin are PPAR-gamma-independent and prevent impairment of insulin sensitivity without affecting body weight and composition.
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Affiliation(s)
- Silvia Wein
- Institute of Animal Nutrition & Physiology, Christian-Albrechts-University of Kiel, Herrmann-Rodewald-Str 9, D-24118 Kiel, Germany.
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14
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Hao Q, Hansen JB, Petersen RK, Hallenborg P, Jørgensen C, Cinti S, Larsen PJ, Steffensen KR, Wang H, Collins S, Wang J, Gustafsson JA, Madsen L, Kristiansen K. ADD1/SREBP1c activates the PGC1-alpha promoter in brown adipocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:421-9. [PMID: 19962449 DOI: 10.1016/j.bbalip.2009.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 11/18/2009] [Accepted: 11/21/2009] [Indexed: 01/24/2023]
Abstract
Cold adaptation elicits a paradoxical simultaneous induction of fatty acid synthesis and beta-oxidation in brown adipose tissue. We show here that cold exposure coordinately induced liver X receptor alpha (LXRalpha), adipocyte determination and differentiation-dependent factor 1 (ADD1)/sterol regulatory element-binding protein-1c (SREBP1c) and peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC1alpha) in brown and inguinal white adipose tissues, but not in epididymal white adipose tissue. Using in vitro models of white and brown adipocytes we demonstrate that beta-adrenergic stimulation induced expression of LXRalpha, ADD1/SREBP1c and PGC1alpha in cells with a brown-like adipose phenotype. We demonstrate that ADD1/SREBP1c is a powerful inducer of PGC1alpha expression via a conserved E box in the proximal promoter and that beta-adrenergic stimulation led to recruitment of ADD1/SREBP1c to this E box. The ability of ADD1/SREBP1c to activate the PGC1alpha promoter exhibited a striking cell type dependency, suggesting that additional cell type-restricted factors contribute to ADD1/SREBP1c-mediated activation. In conclusion, our data demonstrate a novel role of ADD1/SREBP1c as a regulator of PGC1alpha expression in brown adipose tissue.
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Affiliation(s)
- Qin Hao
- Beijing Institute of Genomics, Chinese Academy of Science, Beijing 100029, China
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15
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Christensen KB, Petersen RK, Petersen S, Kristiansen K, Christensen LP. Activation of PPARgamma by metabolites from the flowers of purple coneflower (Echinacea purpurea). J Nat Prod 2009; 72:933-937. [PMID: 19374389 DOI: 10.1021/np900003a] [Citation(s) in RCA: 22] [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] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Thiazolidinediones are insulin sensitizing drugs that target the peroxisome proliferator-activated receptor (PPAR) gamma. An n-hexane extract of the flowers of Echinacea purpurea was found to activate PPARgamma without stimulating adipocyte differentiation. Bioassay-guided fractionations yielded five alkamides, of which one was new, and three fatty acids that all activated PPARgamma. The new alkamide hexadeca-2E,9Z,12Z,14E-tetraenoic acid isobutylamide (5) was identified by analysis of spectroscopic data and found to activate PPARgamma with no concurrent stimulation of adipocyte differentiation. Compound 5 was further shown to increase insulin-stimulated glucose uptake. The data suggest that flowers of E. purpurea contain compounds with potential to manage insulin resistance and type 2 diabetes.
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Affiliation(s)
- Kathrine B Christensen
- Department of Food Science, University of Aarhus, Kirstinebjergvej 10, 5792 Aarslev, Denmark.
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16
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Markt P, Petersen RK, Flindt EN, Kristiansen K, Kirchmair J, Spitzer G, Distinto S, Schuster D, Wolber G, Laggner C, Langer T. Discovery of Novel PPAR Ligands by a Virtual Screening Approach Based on Pharmacophore Modeling, 3D Shape, and Electrostatic Similarity Screening. J Med Chem 2008; 51:6303-17. [DOI: 10.1021/jm800128k] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Madsen L, Petersen RK, Steffensen KR, Pedersen LM, Hallenborg P, Ma T, Frøyland L, Døskeland SO, Gustafsson JÅ, Kristiansen K. Activation of Liver X Receptors Prevents Statin-induced Death of 3T3-L1 Preadipocytes. J Biol Chem 2008; 283:22723-36. [DOI: 10.1074/jbc.m800720200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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18
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Jakobsen MA, Petersen RK, Kristiansen K, Lange M, Lillevang ST. Peroxisome proliferator-activated receptor alpha, delta, gamma1 and gamma2 expressions are present in human monocyte-derived dendritic cells and modulate dendritic cell maturation by addition of subtype-specific ligands. Scand J Immunol 2006; 63:330-7. [PMID: 16640656 DOI: 10.1111/j.1365-3083.2006.01745.x] [Citation(s) in RCA: 40] [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: 12/16/2022]
Abstract
It has recently been shown by Chang et al. (J Immunol 2000;165:3584-91) that the maturation of dendritic cells (DC) in the presence of long-chain fatty acids redirects DC into Th0/Th2-inducing cells suggesting the involvement of a receptor for long-chain fatty acids like members of the peroxisome proliferator-activated receptors (PPAR) superfamily. Here, we show that immature and mature monocyte-derived DC (Mo-DC) express PPARalpha, PPARdelta, PPARgamma1 and PPARgamma2 mRNA with the highest level of PPARgamma1 mRNA. We were only able to observe the expression of PPARgamma1 protein by Western blotting probably because the protein level of the other subtypes is below the detection limit. Synthetic ligands specific for PPARalpha, PPARdelta or PPARgamma added at day 0-6 have similar effect on the maturation of Mo-DC driving the maturation of Mo-DC with atypical phenotype, reduced expression of IL-10, IL-12 p35 and IL-12 p40 mRNA and with reduced stimulatory effects in mixed leucocyte reaction (MLR). Our data suggest that naturally occurring PPAR ligands like fatty acids and fatty acid derivates have anti-inflammatory effects by redirecting DC into a less stimulatory mode.
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Affiliation(s)
- M A Jakobsen
- Department of Clinical Immunology, Odense University Hospital, Odense, Denmark.
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19
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Iankova I, Petersen RK, Annicotte JS, Chavey C, Hansen JB, Kratchmarova I, Sarruf D, Benkirane M, Kristiansen K, Fajas L. Peroxisome proliferator-activated receptor gamma recruits the positive transcription elongation factor b complex to activate transcription and promote adipogenesis. Mol Endocrinol 2006; 20:1494-505. [PMID: 16484339 PMCID: PMC2259259 DOI: 10.1210/me.2005-0222] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [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: 01/04/2023] Open
Abstract
Positive transcription elongation factor b (P-TEFb) phosphorylates the C-terminal domain of RNA polymerase II, facilitating transcriptional elongation. In addition to its participation in general transcription, P-TEFb is recruited to specific promoters by some transcription factors such as c-Myc or MyoD. The P-TEFb complex is composed of a cyclin-dependent kinase (cdk9) subunit and a regulatory partner (cyclin T1, cyclin T2, or cyclin K). Because cdk9 has been shown to participate in differentiation processes, such as muscle cell differentiation, we studied a possible role of cdk9 in adipogenesis. In this study we show that the expression of the cdk9 p55 isoform is highly regulated during 3T3-L1 adipocyte differentiation at RNA and protein levels. Furthermore, cdk9, as well as cyclin T1 and cyclin T2, shows differences in nuclear localization at distinct stages of adipogenesis. Overexpression of cdk9 increases the adipogenic potential of 3T3-L1 cells, whereas inhibition of cdk9 by specific cdk inhibitors, and dominant-negative cdk9 mutant impairs adipogenesis. We show that the positive effects of cdk9 on the differentiation of 3T3-L1 cells are mediated by a direct interaction with and phosphorylation of peroxisome proliferator-activated receptor gamma (PPARgamma), which is the master regulator of this process, on the promoter of PPARgamma target genes. PPARgamma-cdk9 interaction results in increased transcriptional activity of PPARgamma and therefore increased adipogenesis.
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Affiliation(s)
- Irena Iankova
- Endocrinologie moléculaire et cellulaire des cancers
INSERM : U540Université Montpellier I60 rue de Navacelles
34090 Montpellier,FR
| | - Rasmus K. Petersen
- Department of Biochemistry and Molecular Biology
University of Southern DenmarkDK-5230 Odense M,DK
| | - Jean-Sébastien Annicotte
- Endocrinologie moléculaire et cellulaire des cancers
INSERM : U540Université Montpellier I60 rue de Navacelles
34090 Montpellier,FR
| | - Carine Chavey
- Endocrinologie moléculaire et cellulaire des cancers
INSERM : U540Université Montpellier I60 rue de Navacelles
34090 Montpellier,FR
| | - Jacob B. Hansen
- Department of Biochemistry and Molecular Biology
University of Southern DenmarkDK-5230 Odense M,DK
| | - Irina Kratchmarova
- Department of Biochemistry and Molecular Biology
University of Southern DenmarkDK-5230 Odense M,DK
| | - David Sarruf
- Endocrinologie moléculaire et cellulaire des cancers
INSERM : U540Université Montpellier I60 rue de Navacelles
34090 Montpellier,FR
| | - Monsef Benkirane
- IGH, Institut de génétique humaine
CNRS : UPR1142institut de Génétique humaine
141 Rue de la Cardonille
34396 MONTPELLIER CEDEX 5,FR
| | - Karsten Kristiansen
- Department of Biochemistry and Molecular Biology
University of Southern DenmarkDK-5230 Odense M,DK
| | - Lluis Fajas
- Endocrinologie moléculaire et cellulaire des cancers
INSERM : U540Université Montpellier I60 rue de Navacelles
34090 Montpellier,FR
- Hôpital Arnaud de Villeneuve
CHRU MontpellierHôpital Arnaud de VilleneuveUniversité Montpellier IMontpellier,FR
- * Correspondence should be adressed to: Lluis Lf Fajas
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20
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Kang S, Bajnok L, Longo KA, Petersen RK, Hansen JB, Kristiansen K, MacDougald OA. Effects of Wnt signaling on brown adipocyte differentiation and metabolism mediated by PGC-1alpha. Mol Cell Biol 2005; 25:1272-82. [PMID: 15684380 PMCID: PMC548004 DOI: 10.1128/mcb.25.4.1272-1282.2005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Accepted: 11/09/2004] [Indexed: 12/29/2022] Open
Abstract
Activation of canonical Wnt signaling inhibits brown adipogenesis of cultured cells by impeding induction of PPARgamma and C/EBPalpha. Although enforced expression of these adipogenic transcription factors restores lipid accumulation and expression of FABP4 in Wnt-expressing cells, additional expression of PGC-1alpha is required for activation of uncoupling protein 1 (UCP1). Wnt10b blocks brown adipose tissue development and expression of UCP1 when expressed from the fatty acid binding protein 4 promoter, even when mice are administered a beta3-agonist. In differentiated brown adipocytes, activation of Wnt signaling suppresses expression of UCP1 through repression of PGC-1alpha. Consistent with these in vitro observations, UCP1-Wnt10b transgenic mice, which express Wnt10b in interscapular tissue, lack functional brown adipose tissue. While interscapular tissue of UCP1-Wnt10b mice lacks expression of PGC-1alpha and UCP1, the presence of unilocular lipid droplets and expression of white adipocyte genes suggest conversion of brown adipose tissue to white. Reciprocal expression of Wnt10b with UCP1 and PGC-1alpha in interscapular tissue from cold-challenged or genetically obese mice provides further evidence for regulation of brown adipocyte metabolism by Wnt signaling. Taken together, these data suggest that activation of canonical Wnt signaling early in differentiation blocks brown adipogenesis, whereas activating Wnt signaling in mature brown adipocytes stimulates their conversion to white adipocytes.
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Affiliation(s)
- Sona Kang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1301 E. Catherine Rd., Ann Arbor, MI 48109-0622, USA
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21
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Bezy O, Elabd C, Cochet O, Petersen RK, Kristiansen K, Dani C, Ailhaud G, Amri EZ. Delta-interacting protein A, a new inhibitory partner of CCAAT/enhancer-binding protein beta, implicated in adipocyte differentiation. J Biol Chem 2005; 280:11432-8. [PMID: 15644333 DOI: 10.1074/jbc.m411741200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [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: 11/06/2022] Open
Abstract
CCAAT/enhancer-binding protein beta (C/EBP beta) is expressed early during the adipocyte differentiation program and plays an important role in this process. In an attempt to identify novel proteins that interact with C/EBP beta, we performed a yeast two-hybrid screen with a preadipocyte cDNA library and identified a new co-regulator, delta-interacting protein A (DIPA). DIPA mRNA is expressed during adipocyte differentiation of clonal cell lines. DIPA interacts with C/EBP beta and -delta proteins in intact cells and inhibits their transcriptional activity but not that of C/EBP alpha. Stable overexpression of DIPA in preadipocytes partially inhibits adipocyte differentiation, whereas its gene silencing enhances this process. DIPA and C/EBP beta co-localize in the nucleus, and overexpression of DIPA in preadipocytes results in a partial inhibition of the mitotic clonal expansion which is critical for differentiation. Thus, DIPA is a novel partner of C/EBP beta that down-regulates early events of adipogenesis.
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Affiliation(s)
- Olivier Bezy
- Institute of Signaling, Developmental Biology, and Cancer Research, Centre de Biochimie, UMR 6543 CNRS, Faculté des Sciences, Parc Valrose, 06108 Nice cedex 2, France
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22
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Hansen JB, Jørgensen C, Petersen RK, Hallenborg P, De Matteis R, Bøye HA, Petrovic N, Enerbäck S, Nedergaard J, Cinti S, te Riele H, Kristiansen K. Retinoblastoma protein functions as a molecular switch determining white versus brown adipocyte differentiation. Proc Natl Acad Sci U S A 2004; 101:4112-7. [PMID: 15024128 PMCID: PMC384703 DOI: 10.1073/pnas.0301964101] [Citation(s) in RCA: 229] [Impact Index Per Article: 11.5] [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: 11/18/2022] Open
Abstract
Adipocyte precursor cells give raise to two major cell populations with different physiological roles: white and brown adipocytes. Here we demonstrate that the retinoblastoma protein (pRB) regulates white vs. brown adipocyte differentiation. Functional inactivation of pRB in wild-type mouse embryo fibroblasts (MEFs) and white preadipocytes by expression of simian virus 40 large T antigen results in the expression of the brown fat-specific uncoupling protein 1 (UCP-1) in the adipose state. Retinoblastoma gene-deficient (Rb-/-) MEFs and stem cells, but not the corresponding wild-type cells, differentiate into adipocytes with a gene expression pattern and mitochondria content resembling brown adipose tissue. pRB-deficient MEFs exhibit an increased expression of the Forkhead transcription factor Foxc2 and its target gene cAMP-dependent protein kinase regulatory subunit RIalpha, resulting in increased cAMP sensitivity. Suppression of cAMP-dependent protein kinase activity in Rb(-/-)MEFs blocked the brown adipocyte-like gene expression pattern without affecting differentiation per se. Immunohistochemical studies revealed that pRB is present in the nuclei of white but not brown adipocyte precursor cells at a developmental stage where both cell types begin to accumulate lipid and brown adipocytes express UCP-1. Furthermore, pRB rapidly undergoes phosphorylation upon cold-induced neodifferentiation and up-regulation of UCP-1 expression in brown adipose tissue. Finally, down-regulation of pRB expression accompanies transdifferentiation of white into brown adipocytes in response to beta3-adrenergic receptor agonist treatment. We propose that pRB acts as a molecular switch determining white vs. brown adipogenesis, suggesting a previously uncharacterized function of this key cell cycle regulator in adipocyte lineage commitment and differentiation.
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Affiliation(s)
- Jacob B Hansen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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23
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Petersen RK, Jørgensen C, Rustan AC, Frøyland L, Muller-Decker K, Furstenberger G, Berge RK, Kristiansen K, Madsen L. Arachidonic acid-dependent inhibition of adipocyte differentiation requires PKA activity and is associated with sustained expression of cyclooxygenases. J Lipid Res 2003; 44:2320-30. [PMID: 12923227 DOI: 10.1194/jlr.m300192-jlr200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [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: 11/20/2022] Open
Abstract
Arachidonic acid inhibits adipocyte differentiation of 3T3-L1 cells via a prostaglandin synthesis-dependent pathway. Here we show that this inhibition requires the presence of a cAMP-elevating agent during the first two days of treatment. Suppression of protein kinase A activity by H-89 restored differentiation in the presence of arachidonic acid. Arachidonic acid treatment led to a prolonged activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), and suppression of ERK1/2 activity by the addition of U0126 rescued differentiation. Upon induction of differentiation, expression of cyclooxygenase-2 (COX-2) was transiently induced and then declined, whereas COX-1 expression declined gradually as differentiation progressed. Treatment with arachidonic acid led to sustained expression of COX-1 and COX-2. Omission of a cAMP-elevating agent or addition of H-89 or U0126 prevented sustained expression of COX-2. Unexpectedly, we observed that selective COX-1 or COX-2 inhibitors rescued adipocyte differentiation in the presence of arachidonic acid as effectively as did the nonselective COX-inhibitor indomethacin. De novo fatty acid synthesis, diacylglycerol acyltransferase (DGAT) activity, and triacylglycerol accumulation were repressed in cells treated with arachidonic acid. Indomethacin restored DGAT activity and triacylglycerol accumulation without restoring de novo fatty acid synthesis, resulting in an enhanced incorporation of arachidonic acid into cellular triacylglycerols.
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Affiliation(s)
- Rasmus K Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
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24
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Zhang H, Nøohr J, Jensen CH, Petersen RK, Bachmann E, Teisner B, Larsen LK, Mandrup S, Kristiansen K. Insulin-like growth factor-1/insulin bypasses Pref-1/FA1-mediated inhibition of adipocyte differentiation. J Biol Chem 2003; 278:20906-14. [PMID: 12651852 DOI: 10.1074/jbc.m300022200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [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: 01/02/2023] Open
Abstract
Pref-1 is a highly glycosylated Delta-like transmembrane protein containing six epidermal growth factor-like repeats in the extracellular domain. Pref-1 is abundantly expressed in preadipocytes, but expression is down-regulated during adipocyte differentiation. Forced expression of Pref-1 in 3T3-L1 cells was reported to inhibit adipocyte differentiation. Here we show that efficient and regulated processing of Pref-1 occurs in 3T3-L1 preadipocytes releasing most of the extracellular domain as a 50-kDa heterogeneous protein, previously isolated and characterized as FA1. Unexpectedly, we found that forced expression of the soluble form, FA1, or full-length Pref-1 did not inhibit adipocyte differentiation of 3T3-L1 cells when differentiation was induced by standard treatment with methylisobutylxanthine, dexamethasone, and high concentrations of insulin. However, forced expression of either form of Pref-1/FA1 in 3T3-L1 or 3T3-F442A cells inhibited adipocyte differentiation when insulin or insulin-like growth factor-1 (IGF-1) was omitted from the differentiation mixture. We demonstrate that the level of the mature form of the IGF-1 receptor is reduced and that IGF-1-dependent activation of p42/p44 mitogen-activated protein kinases (MAPKs) is compromised in preadipocytes with forced expression of Pref-1. This is accompanied by suppression of clonal expansion and terminal differentiation. Accordingly, supplementation with insulin or IGF-1 rescued p42/p44 MAPK activation, clonal expansion, and adipocyte differentiation in a dose-dependent manner.
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Affiliation(s)
- Hongbin Zhang
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M., Denmark
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25
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Hansen JB, Petersen RK, Jørgensen C, Kristiansen K. Deregulated MAPK activity prevents adipocyte differentiation of fibroblasts lacking the retinoblastoma protein. J Biol Chem 2002; 277:26335-9. [PMID: 12000769 DOI: 10.1074/jbc.m203870200] [Citation(s) in RCA: 32] [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] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A functional retinoblastoma protein (pRB) is required for adipose conversion of preadipocyte cell lines and primary mouse embryo fibroblasts (MEFs) in response to treatment with standard adipogenic inducers. Interestingly, lack of functional pRB in MEFs was recently linked to elevated Ras activity. Ras-dependent signaling plays a significant, although incompletely understood, role in adipocyte differentiation, because activated Ras has been reported to either promote or inhibit adipogenesis depending on the cellular context. In various cell types activation of Ras leads to activation of the mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase 1/2 (ERK1/2), and protein kinase B (PKB)/Akt, which exert opposing effects on adipogenesis, with ERK1/2 inhibiting and PKB/Akt promoting terminal differentiation. Here we report that the levels of activated ERK1/2 and PKB/Akt are significantly increased in pRB-deficient MEFs both before and after the addition of adipogenic inducers. Consistently, we detected higher levels of activated Ras in MEFs lacking pRB. Suppression of ERK1/2 activation by the MEK inhibitor UO126 restored the ability of pRB-deficient MEFs to undergo adipocyte differentiation, as manifested by expression of adipocyte marker genes and lipid accumulation. Furthermore and reflecting the elevated levels of activated PKB/Akt in the pRB-deficient MEFs, differentiation proceeded in an insulin-independent manner. In conclusion, we suggest that pRB plays a pivotal role in adipogenesis by suppressing MAPK activity.
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Affiliation(s)
- Jacob B Hansen
- Department of Biochemistry and Molecular Biology, Center for Experimental BioInformatics, University of Southern Denmark, DK-5230 Odense M, Denmark
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26
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Hansen JB, Zhang H, Rasmussen TH, Petersen RK, Flindt EN, Kristiansen K. Peroxisome proliferator-activated receptor delta (PPARdelta )-mediated regulation of preadipocyte proliferation and gene expression is dependent on cAMP signaling. J Biol Chem 2001; 276:3175-82. [PMID: 11069900 DOI: 10.1074/jbc.m005567200] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [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: 11/06/2022] Open
Abstract
The peroxisome proliferator-activated receptor gamma (PPARgamma) is a key regulator of terminal adipocyte differentiation. PPARdelta is expressed in preadipocytes, but the importance of this PPAR subtype in adipogenesis has been a matter of debate. Here we present a critical evaluation of the role of PPARdelta in adipocyte differentiation. We demonstrate that treatment of NIH-3T3 fibroblasts overexpressing PPARdelta with standard adipogenic inducers led to induction of PPARgamma2 expression and terminal adipocyte differentiation in a manner that was strictly dependent on simultaneous administration of a PPARdelta ligand and methylisobutylxanthine (MIX) or other cAMP elevating agents. We further show that ligands and MIX synergistically stimulated PPARdelta-mediated transactivation. In 3T3-L1 preadipocytes, simultaneous administration of a PPARdelta-selective ligand and MIX significantly enhanced the early expression of PPARgamma and ALBP/aP2, but only modestly promoted terminal differentiation as determined by lipid accumulation. Finally, we provide evidence that synergistic activation of PPARdelta promotes mitotic clonal expansion in 3T3-L1 cells with or without forced expression of PPARdelta. In conclusion, our results suggest that PPARdelta may play a role in the proliferation of adipocyte precursor cells, whereas activation of endogenous PPARdelta in 3T3-L1 cells appears to have only minor impact on the processes leading to terminal adipocyte differentiation.
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Affiliation(s)
- J B Hansen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense University, DK-5230 Odense M, Denmark
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27
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Hansen JB, Petersen RK, Larsen BM, Bartkova J, Alsner J, Kristiansen K. Activation of peroxisome proliferator-activated receptor gamma bypasses the function of the retinoblastoma protein in adipocyte differentiation. J Biol Chem 1999; 274:2386-93. [PMID: 9891007 DOI: 10.1074/jbc.274.4.2386] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.9] [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: 01/19/2023] Open
Abstract
The retinoblastoma protein (pRB) is an important regulator of development, proliferation, and cellular differentiation. pRB was recently shown to play a pivotal role in adipocyte differentiation, to interact physically with adipogenic CCAAT/enhancer-binding proteins (C/EBPs), and to positively regulate transactivation by C/EBPbeta. We show that PPARgamma-mediated transactivation is pRB-independent, and that ligand-induced transactivation by PPARgamma1 present in RB+/+ and RB-/- mouse embryo fibroblasts is sufficient to bypass the differentiation block imposed by the absence of pRB. The differentiated RB-/- cells accumulate lipid and express adipocyte markers, including C/EBPalpha and PPARgamma2. Interestingly, adipose conversion of pRB-deficient cells occurs in the absence of compensatory up-regulations of the other pRB family members p107 and p130. RB+/+ as well as RB-/- cells efficiently exit from the cell cycle after completion of clonal expansion following stimulation with adipogenic inducers. We conclude that ligand-induced activation of endogenous PPARgamma1 in mouse embryo fibroblasts is sufficient to initiate a transcriptional cascade resulting in induction of PPARgamma2 and C/EBPalpha expression, withdrawal from the cell cycle, and terminal differentiation in the absence of a functional pRB.
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Affiliation(s)
- J B Hansen
- Department of Molecular Biology, Odense University, DK-5230 Odense M, Denmark
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Abstract
A simple ELISA test to detect antibodies against scabby mouth virus (SMV) has been developed. Native whole virions and subunits of SMV generated by boiling the virus in the presence of sodium dodecyl sulphate (SDS) detergent and beta-mercaptoethanol were compared as ELISA assay reagents using naive and hyperimmune sera from sheep and rabbits. Approximately 2 x 10(4) intact virus particles per microtiter well were required to generate a positive to negative signal of 0.8:0.3 ELISA O.D. units when the serum was used at a dilution of 1/100. In contrast, total subunit antigen generated by disrupting and coupling of 250-500 virions per well provided a signal ratio of 1.58:0.3 ELISA O.D. units at a serum dilution of 1/250. Total subunit antigens were therefore 400 times more economical to use than intact virions. In addition, subunit antigens could be readily bound to microtiter plates without the need for removal of the SDS. Secondly, it was not necessary to block non-specific binding sites on the plate with blockers such as gelatin and skim-milk, thereby shortening the time needed to complete the ELISA assay. The total subunit antigen ELISA test was used to detect seroconversion in new born lambs where there was an occurrence of SMV infection in housed sheep. Three bleeds were taken at fortnightly intervals and the ELISA results showed that 9 out of 15 lambs were seropositive for all bleed points. Four of the lambs showed a sequential rise in titer while only one lamb failed to seroconvert.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J C Chin
- Elizabeth Macarthur Agricultural Institute, NSW Agriculture, Sydney, Australia
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Steiner KA, Whittington RJ, Petersen RK, Hornitzky C, Garnett H. Purification of epizootic haematopoietic necrosis virus and its detection using ELISA. J Virol Methods 1991; 33:199-209. [PMID: 1939507 DOI: 10.1016/0166-0934(91)90019-v] [Citation(s) in RCA: 16] [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] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Epizootic haematopoietic necrosis virus (EHNV) was grown in Bluegill fry (BF-2) cells and purified using differential and gradient centrifugation. The lower band (B2) from 15-60% sucrose gradients contained infective EHNV but few contaminating cell components when assessed by electron microscopy, SDS-PAGE, and Western blotting using anti-BF-2 serum and anti-B2 serum. Both rabbit and sheep anti-B2 sera precipitated B2 in agarose gel immunodiffusion and detected EHNV in cell culture supernatant when used in an indirect antigen-capture ELISA. Rabbit anti-B2 serum was used as capture antibody while sheep anti-B2 serum was used to detect viral antigen. Pre-adsorption of diluted sheep anti-B2 serum using BF-2 cell lysate greatly improved the specificity and sensitivity of the technique.
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Affiliation(s)
- K A Steiner
- Elizabeth Macarthur Agricultural Institute, New South Wales Agriculture and Fisheries, Camden, Australia
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