451
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Zhang YY, Li X, Qian SW, Guo L, Huang HY, He Q, Liu Y, Ma CG, Tang QQ. Transcriptional activation of histone H4 by C/EBPβ during the mitotic clonal expansion of 3T3-L1 adipocyte differentiation. Mol Biol Cell 2011; 22:2165-74. [PMID: 21562223 PMCID: PMC3128520 DOI: 10.1091/mbc.e10-11-0912] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Histone H4 is activated by C/EBPβ in mitotic clonal expansion during adipogenesis. C/EBP-binding sites are identified in histone H4 promoters, and H4 expression is suppressed when C/EBPβ is knocked down or its DNA-binding activity is inhibited by A-C/EBP. These results help in our understanding of how C/EBPβ plays important roles in the proliferation of other cells. CCAAT enhancer binding protein β (C/EBPβ) is required for both mitotic clonal expansion (MCE) and terminal differentiation during the 3T3-L1 adipocyte differentiation program. Whereas the mechanism of C/EBPβ during terminal differentiation is well understood, the mechanism of C/EBPβ in MCE is not. We provide evidence that histone H4, the most conserved cell cycle–related histone, the change of which is strictly correlated with DNA content change during the cell cycle, is transcriptionally activated by C/EBPβ during MCE. Expression of histone H4 is increased at 16 h after induction when 3T3-L1 preadipocytes synchronously reenter S phase, which is correlated with the sequential phosphorylation and activation of C/EBPβ, and expression was partially suppressed when A-C/EBP (dominant negative for C/EBP protein) was overexpressed. One C/EBP-binding site was identified in one of the histone H4 gene promoters (hist4h4), confirmed by both electrophoretic mobility shift assay and chromatin immunoprecipitation assay. C/EBP-binding sites were also found in 9 of 11 other histone H4 promoters, which can also be transactivated by C/EBPβ. Knockdown of C/EBPβ by stealth small interfering RNA partially decreased H4 gene expression and arrested cells in G1 phase as indicated by bromodeoxyuridine incorporation and fluorescence-activated cell sorting analysis of DNA content. This study provides new insights into why C/EBPβ is required for MCE during 3T3-L1 adipocyte differentiation and why C/EBPβ plays important roles in the proliferation of other cell types.
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Affiliation(s)
- You-You Zhang
- The Key Laboratory of Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032, China
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452
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Lee MH, Chen YY, Tsai JW, Wang SC, Watanabe T, Tsai YC. Inhibitory effect of β-asarone, a component of Acorus calamus essential oil, on inhibition of adipogenesis in 3T3-L1 cells. Food Chem 2011. [DOI: 10.1016/j.foodchem.2010.08.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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453
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Noda N, Honma S, Ohmiya Y. Hes1 is required for contact inhibition of cell proliferation in 3T3-L1 preadipocytes. Genes Cells 2011; 16:704-13. [PMID: 21481105 DOI: 10.1111/j.1365-2443.2011.01518.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cell-cell contact causes the growth arrest of cells in culture, which is referred to as contact inhibition of cell proliferation. Notch signaling is involved in the growth arrest of cells represented by contact inhibition of cell proliferation. The Notch effector, Hes1 (Hairy and enhancer of split 1), promotes or inhibits cell proliferation by repressing the expression of cyclin-dependent kinase inhibitors. However, it is still unclear whether Hes1 is involved in the mechanisms responsible for contact inhibition of cell proliferation. Here, we examined the involvement of Hes1 in contact inhibition of cell proliferation using a γ-secretase inhibitor and a stable 3T3-L1 preadipocyte cell line expressing Hes1-shRNA as a model cell. The cell cycle was not arrested in Hes1-knockdown cells even after the cells reached confluence. Reduced Hes1 levels failed to repress the expression of E2F-1, a transcription factor required for the progression of the cell cycle. The expression of Myc, cyclin E1, and cyclin A2 in E2F-1 target genes was also higher in Hes1-knockdown cells compared with the negative control. These results suggest that Hes1 plays essential roles in contact inhibition of cell proliferation in 3T3-L1 cells by repressing E2F-1 expression.
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Affiliation(s)
- Natsumi Noda
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
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454
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Nie J, Bradshaw AD, Delany AM, Sage EH. Inactivation of SPARC enhances high-fat diet-induced obesity in mice. Connect Tissue Res 2011; 52:99-108. [PMID: 20615096 DOI: 10.3109/03008207.2010.483747] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Secreted protein, acidic and rich in cysteine (SPARC), a matricellular protein, modulates extracellular matrix assembly and turnover in many physiological processes. SPARC-null mice exhibit an increased accumulation of adipose tissue. To distinguish between the functions of SPARC in adipogenesis during development and adulthood, we studied wild-type (WT) and SPARC-null mice maintained on a normal (low-fat) or high-fat (HF) diet. On an HF diet, SPARC-null mice exhibited significantly greater weight gain, in comparison to their WT counterparts, and had an enhanced cortical bone area that was likely due to increased mechanical loading. Diet-induced obesity (DIO) was also associated with an increase in vertebral trabecular bone in WT mice, but a significant change in this parameter was not observed in SPARC-null animals. We show that SPARC inhibits mitotic clonal expansion of preadipocytes at an early stage of adipogenesis. Moreover, there were substantially diminished levels of type I collagen in SPARC-null adipose tissue, as well as a reduction in the number of cross-linked, mature collagen fibers. In the absence of SPARC, mice show enhanced DIO. In adult animals, SPARC functions in the production and remodeling of adipose tissue, as well as in the regulation of preadipocyte differentiation.
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Affiliation(s)
- Jing Nie
- Benaroya Research Institute at Virginia Mason, Seattle, Washington 98101, USA
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455
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Mollah ML, Cheon YP, In JG, Yang DC, Kim YC, Song JC, Kim KS. Inhibitory Effects of Cultivated Wild Ginseng on the Differentiation of 3T3-L1 Pre-adipocytes. J Ginseng Res 2011. [DOI: 10.5142/jgr.2011.35.1.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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456
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Huang-Doran I, Bicknell LS, Finucane FM, Rocha N, Porter KM, Tung YL, Szekeres F, Krook A, Nolan JJ, O’Driscoll M, Bober M, O’Rahilly S, Jackson AP, Semple RK. Genetic defects in human pericentrin are associated with severe insulin resistance and diabetes. Diabetes 2011; 60:925-35. [PMID: 21270239 PMCID: PMC3046854 DOI: 10.2337/db10-1334] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 12/13/2010] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Genetic defects in human pericentrin (PCNT), encoding the centrosomal protein pericentrin, cause a form of osteodysplastic primordial dwarfism that is sometimes reported to be associated with diabetes. We thus set out to determine the prevalence of diabetes and insulin resistance among patients with PCNT defects and examined the effects of pericentrin depletion on insulin action using 3T3-L1 adipocytes as a model system. RESEARCH DESIGN AND METHODS A cross-sectional metabolic assessment of 21 patients with PCNT mutations was undertaken. Pericentrin expression in human tissues was profiled using quantitative real-time PCR. The effect of pericentrin knockdown on insulin action and adipogenesis in 3T3-L1 adipocytes was determined using Oil red O staining, gene-expression analysis, immunoblotting, and glucose uptake assays. Pericentrin expression and localization also was determined in skeletal muscle. RESULTS Of 21 patients with genetic defects in PCNT, 18 had insulin resistance, which was severe in the majority of subjects. Ten subjects had confirmed diabetes (mean age of onset 15 years [range 5-28]), and 13 had metabolic dyslipidemia. All patients without insulin resistance were younger than 4 years old. Knockdown of pericentrin in adipocytes had no effect on proximal insulin signaling but produced a twofold impairment in insulin-stimulated glucose uptake, approximately commensurate with an associated defect in cell proliferation and adipogenesis. Pericentrin was highly expressed in human skeletal muscle, where it showed a perinuclear distribution. CONCLUSIONS Severe insulin resistance and premature diabetes are common features of PCNT deficiency but are not congenital. Partial failure of adipocyte differentiation may contribute to this, but pericentrin deficiency does not impair proximal insulin action in adipocytes.
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Affiliation(s)
- Isabel Huang-Doran
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
| | - Louise S. Bicknell
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, U.K
| | - Francis M. Finucane
- Metabolic Research Unit, St. James Hospital, Trinity College, Dublin, Ireland
| | - Nuno Rocha
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
| | - Keith M. Porter
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
| | - Y.C. Loraine Tung
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
| | - Ferenc Szekeres
- Integrative Physiology, Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Anna Krook
- Integrative Physiology, Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - John J. Nolan
- Metabolic Research Unit, St. James Hospital, Trinity College, Dublin, Ireland
| | - Mark O’Driscoll
- Human DNA Damage Response Disorders Group, University of Sussex, Brighton, U.K
| | - Michael Bober
- Division of Genetics, Department of Pediatrics, Alfred I. DuPont Hospital for Children, Wilmington, Delaware
| | - Stephen O’Rahilly
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
| | - Andrew P. Jackson
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, U.K
| | - Robert K. Semple
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
| | - for the Majewski Osteodysplastic Primordial Dwarfism Study Group
- Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, U.K
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, U.K
- Metabolic Research Unit, St. James Hospital, Trinity College, Dublin, Ireland
- Integrative Physiology, Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
- Human DNA Damage Response Disorders Group, University of Sussex, Brighton, U.K
- Division of Genetics, Department of Pediatrics, Alfred I. DuPont Hospital for Children, Wilmington, Delaware
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457
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Wells L, Slawson C, Hart GW. The E2F-1 associated retinoblastoma-susceptibility gene product is modified by O-GlcNAc. Amino Acids 2011. [PMID: 20680651 DOI: 10.1007/s00726-010-0709-x/figures/4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The retinoblastoma-susceptibility gene product (pRB) is a classical tumor suppressor. pRB regulates a number of cellular processes including proliferation, differentiation, and apoptosis. One of the essential mechanisms by which pRB, and the related p107 and p130 family members, act is through its interactions with the E2F class of transcription factors. E2F-1 transcription is necessary for entry into S-phase during the cell-cycle. pRB binds E2F-1 and represses transcription via recruitment of a histone deacetylase complex and by preventing co-activator complexes from binding E2F-1. Current dogma suggests that phosphorylation of pRB during mid- to late-G1 leads to release of E2F-1 and E2F-1 dependent transcriptional activation of essential S-phase genes. Here we show that pRB, and the related p107 protein, are modified by O-linked β-N-acetylglucosamine (O-GlcNAc) in an in vitro transcription/translation system. Furthermore, we show in vivo that pRB is more heavily glycosylated in G1 of the cell-cycle when pRB is known to be in an active, hypophosphorylated state. Finally, we demonstrate that E2F-1 associated pRB is modified by O-GlcNAc. These studies suggest that regulation of pRB function(s) may be controlled by dynamic O-GlcNAc modification, as well as phosphorylation.
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Affiliation(s)
- Lance Wells
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
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458
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Donzelli E, Lucchini C, Ballarini E, Scuteri A, Carini F, Tredici G, Miloso M. ERK1 and ERK2 are involved in recruitment and maturation of human mesenchymal stem cells induced to adipogenic differentiation. J Mol Cell Biol 2011; 3:123-31. [PMID: 21278199 DOI: 10.1093/jmcb/mjq050] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Adipocytes' biology and the mechanisms that control adipogenesis have gained importance because of the need to develop therapeutic strategies to control obesity and the related pathologies. Human mesenchymal stem cells (hMSCs), undifferentiated stem cells present in the bone marrow that are physiological precursors of adipocytes, were induced to adipogenic differentiation. The molecular mechanisms on the basis of the adipogenesis were evaluated, focusing on the MAPKinases ERK1 and ERK2, which are involved in many biological and cellular processes. ERK1 and ERK2 phosphorylation was reduced with different timing and intensity for the two isoforms in treated hMSCs in comparison with control cells until day 10 and then at 14-28 days, it reached the level of untreated cultures. The total amount of ERK1 was also decreased up to day 10 and then was induced to the level of untreated cultures, whereas the expression of ERK2 was not changed following adipogenic induction. Treatment with the specific ERK1/2 inhibitor U0126 during the whole differentiation period hampered hMSCs' adipogenic differentiation, as lipid droplets appeared in very few cells and were reduced in number and size. When U0126 was administered only during the initial phase of differentiation, the number of hMSCs recruited to adipogenesis was reduced while, when it was administered later, hMSCs did not acquire a mature adipocytic phenotype. ERK1 and ERK2 are important for hMSC adipogenic differentiation since any alteration to the correct timing of their phosphorylation affects either the recruitment into the differentiation program and the extent of their maturation.
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Affiliation(s)
- Elisabetta Donzelli
- Department of Neuroscience and Biomedical Technologies, University of Milano-Bicocca, Via Cadore 48-20052, Monza (MB), Italy.
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459
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Kamalakkannan S, Rajendran R, Venkatesh RV, Clayton P, Akbarsha MA. Effect of <i>Caralluma Fimbriata</i> Extract on 3T3-L1 Pre-Adipocyte Cell Division. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/fns.2011.24047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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460
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Jung HS, Kim YH, Lee JW. Duration and magnitude of extracellular signal-regulated protein kinase phosphorylation determine adipogenesis or osteogenesis in human bone marrow-derived stem cells. Yonsei Med J 2011; 52:165-72. [PMID: 21155050 PMCID: PMC3017693 DOI: 10.3349/ymj.2011.52.1.165] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE Imbalances between osteogenic and adipogenic differentiation leads to diseases such as osteoporosis. The aim of our study was to demonstrate the differences in extracellular signal-regulated kinase (ERK) phosphorylation during both adipogenesis and osteogenesis of human bone marrow-derived stem cells (BMSCs). MATERIALS AND METHODS Using troglitazone, GW9662 and U0126, we investigated their role in hBMSC differentiation to adipogenic and osteogenic fates. RESULTS ERK1/2 inhibition by U0126 suppressed proliferator-activated receptor (PPAR)γ expression and lipid accumulation, while it decreased the mRNA expression of adipogenic genes (lipoprotein lipase, PPARγ, and adipocyte protein) and osteogenic genes (type I collagen and osteopontin). ERK phosphorylation was transient and decreased during adipogenesis, whereas it occurred steadily during osteogenesis. Troglitazone, a PPARγ agonist, induced adipogenesis by inhibiting ERK phosphorylation even in an osteogenic medium, suggesting that ERK signaling needs to be shut off in order to proceed with adipose cell commitment. Cell proliferation was greatly increased in osteogenesis but was not changed during adipogenesis, indicating that ERK might play different roles in cellular proliferation and differentiation between the two committed cell types. CONCLUSION The duration and magnitude of ERK activation might be a crucial factor for the balance between adipogenesis and osteogenesis in human bone marrow-derived stem cells.
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Affiliation(s)
- Ho Sun Jung
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Yun Hee Kim
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Jin Woo Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
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461
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Ferguson BS, Nam H, Hopkins RG, Morrison RF. Impact of reference gene selection for target gene normalization on experimental outcome using real-time qRT-PCR in adipocytes. PLoS One 2010; 5:e15208. [PMID: 21179435 PMCID: PMC3001470 DOI: 10.1371/journal.pone.0015208] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 10/30/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND With the current rise in obesity-related morbidities, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) has become a widely used method for assessment of genes expressed and regulated by adipocytes. In order to measure accurate changes in relative gene expression and monitor intersample variability, normalization to endogenous control genes that do not change in relative expression is commonly used with qRT-PCR determinations. However, historical evidence has clearly demonstrated that the expression profiles of traditional control genes (e.g., β-actin, GAPDH, α-tubulin) are differentially regulated across multiple tissue types and experimental conditions. METHODOLOGY/PRINCIPAL FINDINGS Therefore, we validated six commonly used endogenous control genes under diverse experimental conditions of inflammatory stress, oxidative stress, synchronous cell cycle progression and cellular differentiation in 3T3-L1 adipocytes using TaqMan qRT-PCR. Under each study condition, we further evaluated the impact of reference gene selection on experimental outcome using examples of target genes relevant to adipocyte function and differentiation. We demonstrate that multiple reference genes are regulated in a condition-specific manner that is not suitable for use in target gene normalization. CONCLUSION/SIGNIFICANCE Data are presented demonstrating that inappropriate reference gene selection can have profound influence on study conclusions ranging from divergent statistical outcome to inaccurate data interpretation of significant magnitude. This study validated the use of endogenous controls in 3T3-L1 adipocytes and highlights the impact of inappropriate reference gene selection on data interpretation and study conclusions.
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Affiliation(s)
- Bradley S. Ferguson
- Department of Nutrition, The University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Heesun Nam
- Department of Nutrition, The University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Robin G. Hopkins
- Department of Nutrition, The University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Ron F. Morrison
- Department of Nutrition, The University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
- * E-mail:
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462
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Xu B, Gerin I, Miao H, Vu-Phan D, Johnson CN, Xu R, Chen XW, Cawthorn WP, MacDougald OA, Koenig RJ. Multiple roles for the non-coding RNA SRA in regulation of adipogenesis and insulin sensitivity. PLoS One 2010; 5:e14199. [PMID: 21152033 PMCID: PMC2996286 DOI: 10.1371/journal.pone.0014199] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 11/05/2010] [Indexed: 01/22/2023] Open
Abstract
Peroxisome proliferator-activated receptor-γ (PPARγ) is a master transcriptional regulator of adipogenesis. Hence, the identification of PPARγ coactivators should help reveal mechanisms controlling gene expression in adipose tissue development and physiology. We show that the non-coding RNA, Steroid receptor RNA Activator (SRA), associates with PPARγ and coactivates PPARγ-dependent reporter gene expression. Overexpression of SRA in ST2 mesenchymal precursor cells promotes their differentiation into adipocytes. Conversely, knockdown of endogenous SRA inhibits 3T3-L1 preadipocyte differentiation. Microarray analysis reveals hundreds of SRA-responsive genes in adipocytes, including genes involved in the cell cycle, and insulin and TNFα signaling pathways. Some functions of SRA may involve mechanisms other than coactivation of PPARγ. SRA in adipocytes increases both glucose uptake and phosphorylation of Akt and FOXO1 in response to insulin. SRA promotes S-phase entry during mitotic clonal expansion, decreases expression of the cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1, and increases phosphorylation of Cdk1/Cdc2. SRA also inhibits the expression of adipocyte-related inflammatory genes and TNFα-induced phosphorylation of c-Jun NH2-terminal kinase. In conclusion, SRA enhances adipogenesis and adipocyte function through multiple pathways.
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Affiliation(s)
- Bin Xu
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America.
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463
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Kang SI, Kim MH, Shin HS, Kim HM, Hong YS, Park JG, Ko HC, Lee NH, Chung WS, Kim SJ. A water-soluble extract of Petalonia binghamiae inhibits the expression of adipogenic regulators in 3T3-L1 preadipocytes and reduces adiposity and weight gain in rats fed a high-fat diet. J Nutr Biochem 2010; 21:1251-7. [PMID: 20332066 DOI: 10.1016/j.jnutbio.2009.11.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 11/11/2009] [Accepted: 11/12/2009] [Indexed: 11/18/2022]
Abstract
We previously showed that an ethanolic extract of the edible brown algae Petalonia binghamiae promotes the differentiation of 3T3-L1 preadipocytes and decreases hyperglycemia in streptozotocin-induced diabetic mice. Here, we report that a water-soluble extract of P. binghamiae thalli, prepared by enzymatic digestion, inhibits preadipocyte differentiation and adipogenesis in a dose-dependent manner. In differentiating 3T3-L1 preadipocytes, the extract (designated PBEE) decreased the expression of peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding proteins α and β, and fatty acid-binding protein aP2. It also inhibited the mitotic clonal expansion process of adipocyte differentiation, and it inhibited insulin-stimulated uptake of glucose into mature 3T3-L1 adipocytes by reducing phosphorylation of insulin receptor substrate-1. In rats with high-fat diet (HFD)-induced obesity, PBEE exhibited potent anti-obesity effects. In this animal model, increases in body weight and fat storage were suppressed by the addition of PBEE to the drinking water at 500 mg/L for 30 days. PBEE supplementation reduced serum levels of glutamic pyruvic and glutamic oxaloacetic transaminases and increased the serum level of high-density lipoprotein cholesterol. Moreover, it significantly decreased the accumulation of lipid droplets in liver tissue, suggesting a protective effect against HFD-induced hepatic steatosis. Taken together, these data demonstrate that PBEE inhibits preadipocyte differentiation and adipogenesis in cultured cells and in rodent models of obesity.
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Affiliation(s)
- Seong-Il Kang
- Department of Biology, Jeju National University, Jejusi, Jeju 690-756, Korea
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464
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Cignarelli A, Melchiorre M, Peschechera A, Conserva A, Renna LA, Miccoli S, Natalicchio A, Perrini S, Laviola L, Giorgino F. Role of UBC9 in the regulation of the adipogenic program in 3T3-L1 adipocytes. Endocrinology 2010; 151:5255-66. [PMID: 20881252 DOI: 10.1210/en.2010-0417] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The small ubiquitin-like modifier-conjugating enzyme UBC9, involved in protein modification through covalent attachment of small ubiquitin-like modifier and other less defined mechanisms, has emerged as a key regulator of cell proliferation and differentiation. To explore the role of UBC9 in adipocyte differentiation, the UBC9 protein levels were examined in differentiating 3T3-L1 cells. UBC9 mRNA and protein levels were increased 2.5-fold at d 2 and then gradually declined to basal levels at d 8 of differentiation. In addition, UBC9 was expressed predominantly in the nucleus of preadipocytes but shifted to cytoplasmic compartments after d 4, after induction of differentiation. UBC9 knockdown was then achieved in differentiating 3T3-L1 preadipocytes using a specific small interfering RNA. Oil-Red-O staining demonstrated accumulation of large triglyceride droplets in approximately 90% of control cells, whereas lipid droplets were smaller and evident in only 30% of cells treated with the UBC9-specific small interfering RNA. CCAAT/enhancer-binding protein (C/EBP)-δ, peroxisome proliferator-activated receptor-γ, and C/EBPα mRNA levels were increased severalfold 2-6 d after induction of differentiation in control cells, whereas the expression of these transcription factors was significantly lower in the presence of UBC9 gene silencing. Adenovirus-mediated overexpression of a catalytically inactive mutant UBC9 protein in 3T3-L1 cells resulted in no changes in expression of adipogenic transcription factors and conversion to mature adipocytes as compared with control. In conclusion, UBC9 appears to play an important role in adipogenesis. The temporal profile of UBC9 induction and its ability to affect C/EBPδ mRNA induction support a role for this protein during early adipogenesis.
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Affiliation(s)
- Angelo Cignarelli
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, Università degli Studi di Bari Aldo Moro, I-70124 Bari, Italy
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465
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Zúñiga LA, Shen WJ, Joyce-Shaikh B, Pyatnova EA, Richards AG, Thom C, Andrade SM, Cua DJ, Kraemer FB, Butcher EC. IL-17 regulates adipogenesis, glucose homeostasis, and obesity. THE JOURNAL OF IMMUNOLOGY 2010; 185:6947-59. [PMID: 21037091 DOI: 10.4049/jimmunol.1001269] [Citation(s) in RCA: 274] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Inflammatory mediators have the potential to impact a surprising range of diseases, including obesity and its associated metabolic syndrome. In this paper, we show that the proinflammatory cytokine IL-17 inhibits adipogenesis, moderates adipose tissue (AT) accumulation, and regulates glucose metabolism in mice. IL-17 deficiency enhances diet-induced obesity in mice and accelerates AT accumulation even in mice fed a low-fat diet. In addition to potential systemic effects, IL-17 is expressed locally in AT by leukocytes, predominantly by γδ T cells. IL-17 suppresses adipocyte differentiation from mouse-derived 3T3-L1 preadipocytes in vitro, and inhibits expression of genes encoding proadipogenic transcription factors, adipokines, and molecules involved in lipid and glucose metabolism. IL-17 also acts on differentiated adipocytes, impairing glucose uptake, and young IL-17-deficient mice show enhanced glucose tolerance and insulin sensitivity. Our findings implicate IL-17 as a negative regulator of adipogenesis and glucose metabolism in mice, and show that it delays the development of obesity.
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Affiliation(s)
- Luis A Zúñiga
- Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305-5324, USA
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466
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Xiao L, Zhang J, Li H, Liu J, He L, Zhang J, Zhai Y. Inhibition of adipocyte differentiation and adipogenesis by the traditional Chinese herb Sibiraea angustata. Exp Biol Med (Maywood) 2010; 235:1442-9. [PMID: 20962015 DOI: 10.1258/ebm.2010.010167] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Obesity has become a major health concern due to its strong association with the metabolic syndrome. Inhibition of adipocyte differentiation represents a key strategy to inhibit obesity. Sibiraea angustata (SA), a traditional Chinese herb, has a wide range of pharmacological effects, such as improving digestive functions. Here, we report a novel antiadipogenic effect of SA. By using the SA water extract (SAW), SA acetic ether extract (SAA) and the 3T3-L1 model of adipocyte differentiation and adipogenesis, we showed that both SAW and SAA impaired the proliferation and adipo-differentiation of 3T3-L1 in a dose- and time-dependent manner. At the molecular level, treatment of 3T3-L1 cells with SAW or SAA inhibited the expression of the key adipocyte differentiation regulator CCAAT enhancer binding protein β (C/EBPβ), as well as peroxisome proliferator activated receptor γ, adipocyte protein-2, lipoprotein lipase and glucose transporter 4. Cell cycle analysis showed that both SAW and SAA blocked cell cycle at the G1-S transition phase, causing cells to remain in the preadipocyte state. The expression of CyclinA and cyclin-dependent kinase 2 was also inhibited by SAW and SAA. Treatment with SAW also prevented the localization of C/EBPβ to the centromeres. Taken together, our results show that SA has a potent antiadipogenic effect in 3T3-L1 cells due to the inhibition of adipocyte differentiation and adipogenesis. We propose that SA may be used as a safe and effective neutraceutical to manage obesity.
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Affiliation(s)
- Lei Xiao
- Biomedicine Research Institute and College of Life Sciences, Beijing Normal University, Beijing 100875, China
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467
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The E2F-1 associated retinoblastoma-susceptibility gene product is modified by O-GlcNAc. Amino Acids 2010; 40:877-83. [PMID: 20680651 DOI: 10.1007/s00726-010-0709-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 07/19/2010] [Indexed: 10/19/2022]
Abstract
The retinoblastoma-susceptibility gene product (pRB) is a classical tumor suppressor. pRB regulates a number of cellular processes including proliferation, differentiation, and apoptosis. One of the essential mechanisms by which pRB, and the related p107 and p130 family members, act is through its interactions with the E2F class of transcription factors. E2F-1 transcription is necessary for entry into S-phase during the cell-cycle. pRB binds E2F-1 and represses transcription via recruitment of a histone deacetylase complex and by preventing co-activator complexes from binding E2F-1. Current dogma suggests that phosphorylation of pRB during mid- to late-G1 leads to release of E2F-1 and E2F-1 dependent transcriptional activation of essential S-phase genes. Here we show that pRB, and the related p107 protein, are modified by O-linked β-N-acetylglucosamine (O-GlcNAc) in an in vitro transcription/translation system. Furthermore, we show in vivo that pRB is more heavily glycosylated in G1 of the cell-cycle when pRB is known to be in an active, hypophosphorylated state. Finally, we demonstrate that E2F-1 associated pRB is modified by O-GlcNAc. These studies suggest that regulation of pRB function(s) may be controlled by dynamic O-GlcNAc modification, as well as phosphorylation.
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468
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Coskun H, Summerfield TL, Kniss DA, Friedman A. Mathematical modeling of preadipocyte fate determination. J Theor Biol 2010; 265:87-94. [DOI: 10.1016/j.jtbi.2010.03.047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 03/17/2010] [Accepted: 03/30/2010] [Indexed: 11/16/2022]
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469
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Xiao J, Sun B, Cai GP. Transient expression of interferon-inducible p204 in the early stage is required for adipogenesis in 3T3-L1 cells. Endocrinology 2010; 151:3141-53. [PMID: 20444940 DOI: 10.1210/en.2009-1381] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A member of the interferon-inducible p200 family of proteins, p204, has recently been reported to function in the development of many mesoderm-derived tissues, such as bone, muscle, and cartilage. However, no published study has yet investigated the role of p204 in adipogenesis. Our preliminary experiments showed that p204 can be found in 3T3-L1 preadipocytes, and its expression was up-regulated in a differentiation-dependent manner. As such, we hypothesized that p204 is associated with adipogenesis and focused on the influence of p204 on adipogenesis. In the present study, we investigated the transient elevated expression and cytoplasm-to-nucleus translocation of p204 in the early stage of adipogenesis. To determine the effect of p204 on adipogenesis, p204-siRNA and expression vector were produced for p204 suppression and overexpression, respectively. The knockdown of p204 resulted in a significantly depressed adipocyte differentiation, whereas p204 overexpression promoted adipocyte differentiation. The mRNA expression of adipogenic markers, such as peroxisome-proliferator-activated receptor (PPAR)gamma, CCAAT/enhancer-binding-protein (C/EBP)alpha, lipoprotein lipase, and adipsin, was decreased by p204 suppression and increased by p204 overexpression. A coimmunoprecipitation assay coupled with an indirect immunofluorescence assay also indicated that p204 interacted and colocalized with C/EBPdelta in the nucleus. Furthermore, the knockdown of p204 disrupted the interaction between p204 and C/EBPdelta and partially suppressed the PPARgamma transcriptional activity by dissociating C/EBPdelta with the PPARgamma promoter element. Collectively, our data indicate that the transient expression of p204 in the early stage is indispensable for adipocyte differentiation. Disruption of p204 expression patterns at this stage leads to irreversible damage in fat formation.
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Affiliation(s)
- Jing Xiao
- Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, People's Republic of China
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470
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Kim SK, Kong CS. Anti-adipogenic effect of dioxinodehydroeckol via AMPK activation in 3T3-L1 adipocytes. Chem Biol Interact 2010; 186:24-9. [PMID: 20385110 DOI: 10.1016/j.cbi.2010.04.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 03/30/2010] [Accepted: 04/02/2010] [Indexed: 11/16/2022]
Abstract
Dioxinodehydroeckol (DHE) isolated from Ecklonia cava, has previously been investigated for its inhibition of the differentiation of 3T3-L1 preadipocytes into adipocytes. Levels of lipid accumulation were measured, along with changes in the expression of genes and proteins associated with adipogenesis and lipolysis. Confluent 3T3-L1 preadipocytes in medium with or without different concentrations of DHE for 7 days were differentiated into adipocytes. Lipid accumulation was quantified by measuring direct triglyceride contents and Oil-Red O staining. The expression of genes and proteins associated with adipogenesis and lipolysis was measured using RT-PCR, quantitative real-time RT-PCR and Western blotting analysis. It was found that the presence of DHE significantly reduced lipid accumulation and down-regulated the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma), sterol regulatory element-binding protein 1 (SREBP1) and CCAAT/enhancer-binding proteins (C/EBPalpha) in a dose-dependent manner. Moreover, DHE suppressed regulation of the adipocyte-specific gene promoters such as fatty acid binding protein (FABP4), fatty acid transport protein (FATP1), fatty acid synthase (FAS), lipoprotein lipase (LPL), acyl-CoA synthetase 1 (ACS1), leptin, perilipin and HSL compared to control adipocytes. The specific mechanism mediating the effects of DHE was confirmed by activation of phosphorylated AMP-activated protein kinase (pAMPK). Therefore, these results suggest that DHE exerts anti-adipogenic effect on adipocyte differentiation through the activation and modulation of the AMPK signaling pathway.
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Affiliation(s)
- Se-Kwon Kim
- Marine Bioprocess Research Center, Pukyong National University, Busan, Republic of Korea.
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471
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Kong CS, Kim JA, Ahn BN, Vo TS, Yoon NY, Kim SK. 1-(3',5'-dihydroxyphenoxy)-7-(2'',4'',6-trihydroxyphenoxy)-2,4,9-trihydroxydibenzo-1,4-dioxin inhibits adipocyte differentiation of 3T3-L1 fibroblasts. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2010; 12:299-307. [PMID: 19680725 DOI: 10.1007/s10126-009-9224-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 07/14/2009] [Indexed: 05/28/2023]
Abstract
In this study, we isolated the phloroglucinol derivative, 1-(3',5'-dihydroxyphenoxy)-7-(2'',4'',6-trihydroxyphenoxy)-2,4,9-trihydroxydibenzo-1,4-dioxin (1), from Ecklonia cava and evaluated its potential inhibition on adipocyte differentiation in 3T3-L1 cells. Lipid accumulation along with the expression of several genes associated with adipogenesis and lipolysis was examined at the end of differentiation. Lipid accumulation level was examined by measuring triglyceride content and Oil-Red O staining. The expression levels of several genes and proteins were examined using reverse-transcription polymerase chain reaction (RT-PCR), real-time RT-PCR, and Western blot analysis. Compound 1 significantly reduced lipid accumulation and downregulated peroxisome proliferator-activated receptor-gamma, sterol regulatory element-binding protein 1c, and CCAAT/enhancer-binding proteins alpha in a dose-dependent manner. Moreover, the presence of compound 1 induced downregulation of adipogenic target genes such as fatty acid binding protein 4, fatty acid transport protein 1, fatty acid synthase, acyl-CoA synthetase 1, lipoprotein lipase, and leptin. According to the lipolytic response, compound 1 downregulated perilipin and hormone-sensitive lipase while upregulating tumor necrosis factor alpha. Therefore, these results suggest that compound 1 might decrease lipid accumulation during adipocyte differentiation by modulating adipogenesis and lipogenesis. Furthermore, compound 1 could be developed as a functional agent effective in improving obesity.
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Affiliation(s)
- Chang-Suk Kong
- Marine Bioprocess Research Center, Pukyong National University, Busan, 608-737, South Korea
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472
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Barbatelli G, Murano I, Madsen L, Hao Q, Jimenez M, Kristiansen K, Giacobino JP, De Matteis R, Cinti S. The emergence of cold-induced brown adipocytes in mouse white fat depots is determined predominantly by white to brown adipocyte transdifferentiation. Am J Physiol Endocrinol Metab 2010; 298:E1244-53. [PMID: 20354155 DOI: 10.1152/ajpendo.00600.2009] [Citation(s) in RCA: 562] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The origin of brown adipocytes arising in white adipose tissue (WAT) after cold acclimatization is unclear. Here, we demonstrate that several UCP1-immunoreactive brown adipocytes occurring in WAT after cold acclimatization have a mixed morphology (paucilocular adipocytes). These cells also had a mixed mitochondrioma with classic "brown" and "white" mitochondria, suggesting intermediate steps in the process of direct transformation of white into brown adipocytes (transdifferentiation). Quantitative electron microscopy disclosed that cold exposure (6 degrees C for 10 days) did not induce an increase in WAT preadipocytes. beta(3)-adrenoceptor-knockout mice had a blunted brown adipocyte occurrence upon cold acclimatization. Administration of the beta(3)-adrenoceptor agonist CL316,243 induced the occurrence of brown adipocytes, with the typical morphological features found after cold acclimatization. In contrast, administration of the beta(1)-adrenoceptor agonist xamoterol increased only the number of preadipocytes. These findings indicate that transdifferentiation depends on beta(3)-adrenoceptor activation, whereas preadipocyte recruitment is mediated by beta(1)-adrenoceptor. RT-qPCR experiments disclosed that cold exposure induced enhanced expression of the thermogenic genes and of genes expressed selectively in brown adipose tissue (iBAT) and in both interscapular BAT and WAT. beta(3)-adrenoceptor suppression blunted their expression only in WAT. Furthermore, cold acclimatization induced an increased WAT expression of the gene coding for C/EBPalpha (an antimitotic protein), whereas Ccna1 expression (related to cell proliferation) was unchanged. Overall, our data strongly suggest that the cold-induced emergence of brown adipocytes in WAT predominantly reflects beta(3)-adrenoceptor-mediated transdifferentiation.
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MESH Headings
- Adipocytes, Brown/cytology
- Adipocytes, Brown/physiology
- Adipocytes, Brown/ultrastructure
- Adipocytes, White/cytology
- Adipocytes, White/physiology
- Adipocytes, White/ultrastructure
- Adrenergic beta-3 Receptor Agonists
- Adrenergic beta-Agonists/pharmacology
- Animals
- CCAAT-Enhancer-Binding Protein-alpha/genetics
- CCAAT-Enhancer-Binding Protein-alpha/physiology
- Cell Differentiation/physiology
- Cell Transdifferentiation
- Cold Temperature
- Cyclin A1/genetics
- Cyclin A1/physiology
- Dioxoles/pharmacology
- Female
- Immunohistochemistry
- Ion Channels/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Electron
- Mitochondrial Proteins/physiology
- RNA/chemistry
- RNA/genetics
- Receptors, Adrenergic, beta-3/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Uncoupling Protein 1
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Affiliation(s)
- G Barbatelli
- Department of Molecular Pathology and Innovative Therapies, Faculty of Medicine, University of Ancona (Politecnica delle Marche), Ancona, Italy
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473
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Huang-Doran I, Semple RK. Knockdown of the Alström syndrome-associated gene Alms1 in 3T3-L1 preadipocytes impairs adipogenesis but has no effect on cell-autonomous insulin action. Int J Obes (Lond) 2010; 34:1554-8. [PMID: 20514046 DOI: 10.1038/ijo.2010.92] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Alström syndrome is a rare genetic syndrome associated with early-onset obesity, severe insulin resistance (IR) that is disproportionate to the degree of adiposity and premature diabetes. The ALMS1 gene, which is mutated in Alström syndrome, encodes a giant 460 kDa centrosome- and basal body-associated protein. Its function is unknown, although roles in primary cilia formation and function, intracellular organelle trafficking and, most recently, adipocyte differentiation have been mooted. We now test the hypothesis that the severe IR and dyslipidaemia in Alström syndrome are accounted for by a partial defect in adipogenesis and/or insulin action in mature adipocytes, leading to relative failure of adipose tissue to discharge its role in metabolic homeostasis. Stable knockdown of Alms1 expression by >80% in 3T3-L1 preadipocytes was associated with impairment of lipid accumulation and at least a twofold reduction in adipocyte gene expression following hormonal induction of adipogenesis. This was accompanied by a commensurate defect in insulin-stimulated glucose uptake. Proximal signalling events in response to insulin were unaffected. These results suggest that partial impairment of adipogenesis in Alström syndrome may contribute to the severity of the associated metabolic phenotype, whereas the ability of insulin to stimulate glucose uptake into adipocytes is grossly unimpaired.
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Affiliation(s)
- I Huang-Doran
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
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474
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Matrine inhibits 3T3-L1 preadipocyte differentiation associated with suppression of ERK1/2 phosphorylation. Biochem Biophys Res Commun 2010; 396:691-5. [DOI: 10.1016/j.bbrc.2010.04.163] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Accepted: 04/29/2010] [Indexed: 11/20/2022]
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475
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Berberine inhibits PTP1B activity and mimics insulin action. Biochem Biophys Res Commun 2010; 397:543-7. [PMID: 20515652 DOI: 10.1016/j.bbrc.2010.05.153] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 05/27/2010] [Indexed: 11/22/2022]
Abstract
Type 2 diabetes patients show defects in insulin signal transduction that include lack of insulin receptor, decrease in insulin stimulated receptor tyrosine kinase activity and receptor-mediated phosphorylation of insulin receptor substrates (IRSs). A small molecule that could target insulin signaling would be of significant advantage in the treatment of diabetes. Berberine (BBR) has recently been shown to lower blood glucose levels and to improve insulin resistance in db/db mice partly through the activation of AMP-activated protein kinase (AMPK) signaling and induction of phosphorylation of insulin receptor (IR). However, the underlying mechanism remains largely unknown. Here we report that BBR mimics insulin action by increasing glucose uptake ability by 3T3-L1 adipocytes and L6 myocytes in an insulin-independent manner, inhibiting phosphatase activity of protein tyrosine phosphatase 1B (PTP1B), and increasing phosphorylation of IR, IRS1 and Akt in 3T3-L1 adipocytes. In diabetic mice, BBR lowers hyperglycemia and improves impaired glucose tolerance, but does not increase insulin release and synthesis. The results suggest that BBR represents a different class of anti-hyperglycemic agents.
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476
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Yao Y, Li XB, Zhao W, Zeng YY, Shen H, Xiang H, Xiao H. Anti-obesity effect of an isoflavone fatty acid ester on obese mice induced by high fat diet and its potential mechanism. Lipids Health Dis 2010; 9:49. [PMID: 20482839 PMCID: PMC2889992 DOI: 10.1186/1476-511x-9-49] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 05/19/2010] [Indexed: 12/26/2022] Open
Abstract
Background The novel compound 1a is one of the isoflavone fatty acid esters. In order to investigate the anti-obesity effect of compound 1a and its potential mechanism of influence in adipocyte differentiation, Obese male C57BL/6J mice induced by high-fat diet (HFD) and rat preadipocytes (3T3-L1 cell) were used. Methods After 4-week HFD induction, the obese model was made successfully. After treatment with compound 1a, mice plasma biochemistry parameters were analyzed. In addition, mice hepatic tissue slice was observed. In in vitro research, 3T3-L1 cell differentiation by Oil-Red-O staining and adipocyte apoptosis was detected by flow cytometry. Results The in vivo results implied that compound 1a significantly decreased the body weight, white adipose tissue weight of obesity mice(p < 0.05), reduced leptin and TG in plasma(p < 0.05), elevated HDL-C in serum(p < 0.05). The in vitro results suggested that compound 1a could significantly suppress the adipocyte viability and lipid accumulation in the differentiation of preadipocyte, and induce apoptosis in both preadipocytes and mature adipocytes(p < 0.05). Conclusion Compound 1a regulates serum lipid profiles, decreases adipose tissue mass and body weight gain by inducing adipocyte apoptosis in high fat diet induced mice. Thus, it may be used to treat obese patients with hypercholesterolemia and hypertriglyceridemia.
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Affiliation(s)
- Yao Yao
- Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing 210029, PR China
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477
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Hirota K, Morikawa K, Hanada H, Nonaka M, Nakajima Y, Kobayashi M, Nakajima R. Effect of genistein and daidzein on the proliferation and differentiation of human preadipocyte cell line. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:5821-5827. [PMID: 20397699 DOI: 10.1021/jf903911e] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Isoflavones are known to have several biological activities, including a hypolipidemic effect. However, the mechanism of the lipid lowering effect of genistein remains to be elucidated. There is conflicting evidence on the effect of genistein for the deposition of adipocyte tissues. We examined the effect of the isoflavones on the growth and differentiation of human preadipocyte cells, AML-I. Growth arrest accompanied by the appearance of characteristics of apoptosis was observed by genistein or daidzein treatment under the adipogenic stimulation. The expressions of apoptosis-related proteins, Bad, Akt, and p-Akt, were modulated in the genistein-treated cells by Western blot analysis. On the other hand, exposure of AML-I to the isoflavones increased accumulation of cytoplasmic lipid droplets. Actually, the cytoplasmic expressions of fatty acid synthase (FAS) and peroxisome proliferator-activated receptor (PPAR)-gamma were increased in the genistein-treated cells. Glycosylated forms of the isoflavones genistein and puerarin did not have such activities. These results suggested that only aglycon forms of isoflavones induced not only apoptosis but also lipogenesis in the preadipocyte cell line AML-I. The possible mechanism of these phenomena has been discussed in the text.
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Affiliation(s)
- Kaori Hirota
- Division of Clinical Nutrition, Department of Nutritional Science, Sagami Women's University, Sagamihara, Kanagawa, Japan
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478
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Murad JM, Place CS, Ran C, Hekmatyar SKN, Watson NP, Kauppinen RA, Israel MA. Inhibitor of DNA binding 4 (ID4) regulation of adipocyte differentiation and adipose tissue formation in mice. J Biol Chem 2010; 285:24164-73. [PMID: 20460371 DOI: 10.1074/jbc.m110.128744] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Inhibitor of DNA binding 4 (ID4) is a helix-loop-helix protein that heterodimerizes with basic helix-loop-helix transcription factors inhibiting their function. ID4 expression is important for adipogenic differentiation of the 3T3-L1 cell line, and inhibition of ID4 is associated with a concomitant decrease in CCAAT/enhancer-binding protein alpha and peroxisome proliferator-activated receptor gamma mRNA and protein expression. Mice with a homozygous deletion of Id4 (Id4(-/-)) have reduced body fat and gain much less weight compared with wild-type littermates when placed on diets with high fat content. Mouse embryonic fibroblasts (MEFs) isolated from Id4(-/-) mice have reduced adipogenic potential when compared with wild-type MEFs. In agreement with changes in morphological differentiation, the levels of CCAAT/enhancer-binding protein alpha and peroxisome proliferator-activated receptor gamma were also reduced in MEFs from Id4(-/-) mice. Our results demonstrate the importance of ID4 in adipocyte differentiation and the implications of this regulation for adipose tissue formation.
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Affiliation(s)
- Joana M Murad
- Norris Cotton Cancer Center and Department of Pediatrics, Dartmouth Medical School, Hanover, NH 03755, USA
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479
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Qian SW, Li X, Zhang YY, Huang HY, Liu Y, Sun X, Tang QQ. Characterization of adipocyte differentiation from human mesenchymal stem cells in bone marrow. BMC DEVELOPMENTAL BIOLOGY 2010; 10:47. [PMID: 20459638 PMCID: PMC2881898 DOI: 10.1186/1471-213x-10-47] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Accepted: 05/07/2010] [Indexed: 11/11/2022]
Abstract
Background Adipocyte hyperplasia is associated with obesity and arises due to adipogenic differentiation of resident multipotent stem cells in the vascular stroma of adipose tissue and remote stem cells of other organs. The mechanistic characterization of adipocyte differentiation has been researched in murine pre-adipocyte models (i.e. 3T3-L1 and 3T3-F442A), revealing that growth-arrest pre-adipocytes undergo mitotic clonal expansion and that regulation of the differentiation process relies on the sequential expression of three key transcription factors (C/EBPβ, C/EBPα and PPARγ). However, the mechanisms underlying adipocyte differentiation from multipotent stem cells, particularly human mesenchymal stem cells (hBMSCs), remain poorly understood. This study investigated cell cycle regulation and the roles of C/EBPβ, C/EBPα and PPARγ during adipocyte differentiation from hBMSCs. Results Utilising a BrdU incorporation assay and manual cell counting it was demonstrated that induction of adipocyte differentiation in culture resulted in 3T3-L1 pre-adipocytes but not hBMSCs undergoing mitotic clonal expansion. Knock-down and over-expression assays revealed that C/EBPβ, C/EBPα and PPARγ were required for adipocyte differentiation from hBMSCs. C/EBPβ and C/EBPα individually induced adipocyte differentiation in the presence of inducers; PPARγ alone initiated adipocyte differentiation but the cells failed to differentiate fully. Therefore, the roles of these transcription factors during human adipocyte differentiation are different from their respective roles in mouse. Conclusions The characteristics of hBMSCs during adipogenic differentiation are different from those of murine cells. These findings could be important in elucidating the mechanisms underlying human obesity further.
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Affiliation(s)
- Shu-Wen Qian
- Institute of Stem Cell Research and Regenerative Medicine, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
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480
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Armani A, Mammi C, Marzolla V, Calanchini M, Antelmi A, Rosano GM, Fabbri A, Caprio M. Cellular models for understanding adipogenesis, adipose dysfunction, and obesity. J Cell Biochem 2010; 110:564-72. [DOI: 10.1002/jcb.22598] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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481
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Sakamoto K, Sato Y, Sei M, Ewis AA, Nakahori Y. Proteasome activity correlates with male BMI and contributes to the differentiation of adipocyte in hADSC. Endocrine 2010; 37:274-9. [PMID: 20960262 DOI: 10.1007/s12020-009-9298-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 12/16/2009] [Indexed: 01/09/2023]
Abstract
We have previously reported that 26S proteasome subunit mRNA expressions correlate with male body mass index (BMI). In this study, to investigate whether proteasome activities are correlated with BMI, we recruited 61 healthy young Japanese male subjects, measured proteasome activities in their plasma, and correlated them with their BMI and various metabolic factors. We found that among three different proteasome activities, chymotrypsin-like activity in plasma was positively correlated with BMI in healthy Japanese male subjects. Furthermore, we analyzed proteasome activity in vitro during the differentiation of human adipose-derived stem cell (hADSC) into mature adipocytes. In the early stage of differentiation, proteasome activity was at its highest level, and proteasome inhibitor could inhibit hADSC adipocyte differentiation. Our findings suggest that proteasome is an important controlling factor for the development of obesity and adipogenesis.
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Affiliation(s)
- Kozue Sakamoto
- Department of Human Genetics and Public Health, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
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482
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RSK-mediated phosphorylation in the C/EBP{beta} leucine zipper regulates DNA binding, dimerization, and growth arrest activity. Mol Cell Biol 2010; 30:2621-35. [PMID: 20351173 DOI: 10.1128/mcb.00782-09] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The bZIP transcription factor C/EBPbeta is a target of Ras signaling that has been implicated in Ras-induced transformation and oncogene-induced senescence (OIS). To gain insights into Ras-C/EBPbeta signaling, we investigated C/EBPbeta activation by oncogenic Ras. We show that C/EBPbeta DNA binding is autorepressed and becomes activated by the Ras-Raf-MEK-ERK-p90(RSK) cascade. Inducible phosphorylation by RSK on Ser273 in the leucine zipper was required for DNA binding. In addition, three other modifications (phosphorylation on Tyr109 [p-Tyr109], p-Ser111, and monomethylation of Arg114 [me-Arg114]) within an N-terminal autoinhibitory domain were important for Ras-induced C/EBPbeta activation and cytostatic activity. Apart from its role in DNA binding, Ser273 phosphorylation also creates an interhelical g<-->e' salt bridge with Lys268 that increases attractive electrostatic interactions between paired leucine zippers and promotes homodimerization. Mutating Ser273 to Ala or Lys268 to Glu decreased C/EBPbeta homodimer formation, whereas heterodimerization with C/EBPgamma was relatively unaffected. The S273A substitution also reduced the antiproliferative activity of C/EBPbeta in Ras(V12)-expressing fibroblasts and decreased binding to target cell cycle genes, while a phosphomimetic substitution (S273D) maintained growth arrest function. Our findings identify four novel C/EBPbeta-activating modifications, including RSK-mediated phosphorylation of a bifunctional residue in the leucine zipper that regulates DNA binding and homodimerization and thereby promotes cell cycle arrest.
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483
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Maiuri T, Ho J, Stambolic V. Regulation of adipocyte differentiation by distinct subcellular pools of protein kinase B (PKB/Akt). J Biol Chem 2010; 285:15038-15047. [PMID: 20223817 DOI: 10.1074/jbc.m110.121434] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI3K)-protein kinase B (PKB)/Akt-PTEN signal transduction pathway orchestrates a variety of fundamental cell processes and its deregulation is implicated in many human diseases. Although the importance of this pathway to many cellular functions is well established, the mechanisms by which it achieves context-specific physiological outcomes in response to a variety of stimuli, using a relatively limited pool of effectors, remain largely unknown. Spatial restriction of signaling events is one means by which cells coordinate specific responses using common molecules. To investigate the subcellular location-specific roles of the major PI3K effector PKB/Akt in various cell processes, we have developed a novel experimental system employing cellular compartment-directed PKB/Akt pseudosubstrate inhibitors. Subcellular location-restricted PKB/Akt inhibition in the 3T3L1 adipocyte differentiation model revealed that nuclear and plasma membrane, but not cytoplasmic, PKB/Akt activity is required for terminal adipocyte differentiation. Nuclear and plasma membrane pools of PKB/Akt were found to contribute to distinct stages of adipocyte differentiation, revealing that PKB/Akt activity impacts multiple points of this program. Our work establishes the use of localized pseudosubstrate PKB/Akt inhibitors as an effective method for the dissection of PKB/Akt signaling.
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Affiliation(s)
- Tamara Maiuri
- Ontario Cancer Institute, University Health Network, and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Jason Ho
- Ontario Cancer Institute, University Health Network, and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Vuk Stambolic
- Ontario Cancer Institute, University Health Network, and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
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484
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Abstract
Here, we demonstrate that SENP2, a desumoylating enzyme, plays a critical role in the control of adipogenesis. SENP2 expression was markedly increased upon the induction of adipocyte differentiation, and this increase was dependent on protein kinase A activation. Remarkably, knockdown of SENP2 led to a dramatic attenuation of adipogenesis with a marked decrease in PPARgamma and C/EBPalpha mRNA levels. Knockdown of SENP2 also caused a marked reduction in the level of C/EBPbeta protein but not in that of C/EBPbeta mRNA. Interestingly, sumoylation of C/EBPbeta dramatically increased its ubiquitination and destabilization, and this increase could be reversed by SENP2. In addition, overexpression of C/EBPbeta could overcome the inhibitory effect of SENP2 knockdown on adipogenesis. Furthermore, SENP2 was absolutely required for adipogenesis of preadipocytes implanted into mice. These results establish a critical role for SENP2 in the regulation of adipogenesis by desumoylation and stabilization of C/EBPbeta and in turn by promoting the expression of its downstream effectors, such as PPARgamma and C/EBPalpha.
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485
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Boqué N, Campión J, Milagro FI, Moreno-Aliaga MJ, Martinez JA. Some cyclin-dependent kinase inhibitors-related genes are regulated by vitamin C in a model of diet-induced obesity. Biol Pharm Bull 2010; 32:1462-8. [PMID: 19652391 DOI: 10.1248/bpb.32.1462] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this research was to investigate differential gene expression of cyclin-dependent kinase inhibitors (CKIs) in white adipose tissue (WAT) and liver from high-fat fed male Wistar rats with or without vitamin C (VC) supplementation (750 mg/kg of body weight). After 56 d of experimentation, animals fed on a cafeteria diet increased significantly body weights and total body fat. Reverse transcription-polymerase chain reaction (RT-PCR) studies showed that cafeteria diet decreased p21 and p57 mRNA expression in subcutaneous WAT and increased p21 mRNA in liver. Overall, these data provide new information about the role of high fat intake on mRNA levels of several CKIs with implications in adipogenesis, cell metabolism and weight homeostasis. Interestingly, VC supplementation partially prevented diet-induced adiposity and increased p27 mRNA in liver without any changes in the other tissues and genes analyzed. Thus, hepatic mRNA changes induced by ascorbic acid indicate a possible role of these genes in diet-induced oxidative stress processes.
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Affiliation(s)
- Noemí Boqué
- Institute of Nutrition and Food Science, University of Navarra, Pamplona, Spain
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486
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Park JR, Jung JW, Seo MS, Kang SK, Lee YS, Kang KS. DNER modulates adipogenesis of human adipose tissue-derived mesenchymal stem cells via regulation of cell proliferation. Cell Prolif 2010; 43:19-28. [PMID: 20070733 DOI: 10.1111/j.1365-2184.2009.00650.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVES In recent years, obesity has become a global epidemic, highlighting the necessity for basic research into mechanisms underlying growth of adipose tissue and differentiation of stem cells into adipocytes, in humans. For better understanding of cell signalling in adipogenesis, the role of DNER (delta/Notch-like EGF-related receptor) in adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells (hAMSC) was investigated. MATERIALS AND METHODS To assess the role of DNER in hAMSC adipogenesis, hAMSCs were transfected with DNER small interfering RNA (siDNER). Real-time quantitative reverse transcriptase polymerase chain reactions to assess expression levels of adipogenesis-related genes regulated by siDNER, cell cycle and immunoblot analyses were performed. RESULTS First, it was determined that DNER mRNA was profoundly expressed in hAMSCs and reduced during adipogenic differentiation. Knockdown of DNER altered cell morphology, inhibited proliferation and increased frequency and efficiency of adipogenesis in hAMSC. Expression of CCAAT/enhancer-binding protein delta increased and proportion of cells in S phase decreased by knockdown of DNER, using specific siRNA. Moreover, adipocyte-specific genes including peroxisome proliferator-activated receptor gamma, fatty acid binding protein 4 and perilipin were up-regulated in siDNER compared to the siControl group during adipogenesis in hAMSC. CONCLUSIONS These results indicate that DNER knockdown in hAMSC accelerated onset of adipogenic differentiation by bypassing mitotic clonal expansion during the early stages of adipogenesis.
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Affiliation(s)
- J-R Park
- Laboratory of Stem Cell and Tumor Biology, College of Veterinary Medicine, Seoul National University, Seoul, Korea
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487
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Role of chemerin/CMKLR1 signaling in adipogenesis and osteoblastogenesis of bone marrow stem cells. J Bone Miner Res 2010; 25:222-34. [PMID: 19929432 DOI: 10.1359/jbmr.091106] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Maintenance of healthy bone mass requires a well-coordinated balance between the ongoing processes of bone formation and bone resorption. Bone-forming osteoblasts derive from resident adult stem cells within bone marrow called bone marrow stromal cells (BMSCs). These BMSCs are multipotent and also can give rise to adipocytes, which do not contribute directly to bone formation but may influence bone remodeling through the release of bioactive signaling molecules. Chemerin is a novel adipocyte-derived signaling molecule that promotes adipocyte differentiation. In this study we examined the role of chemerin and the cognate receptors CMKLR1 and CCRL2 as determinants of osteoblast and adipocyte differentiation of the preosteoblast 7F2 cell line and of primary BMSCs. Expression and secretion of chemerin increased dramatically with adipocyte differentiation of these cells. Functionally, knockdown of chemerin or CMKLR1 expression using RNA interference abrogated adipocyte differentiation, clonal expansion, and basal proliferation of BMSCs. In contrast, knockdown of either gene was associated with increased osteoblast marker gene expression and mineralization in response to osteoblastogenic stimuli. Forced expression of the adipogenic transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) induced chemerin expression and partially rescued the loss of adipogenesis associated with chemerin or CMKLR1 knockdown in BMSCs. Taken together, these data support a novel role for chemerin/CMKLR1 signaling in regulating adipogenesis and osteoblastogenesis of bone marrow-derived precursor cells. These data reveal a potential role for this signaling pathway as a modulator of bone mass.
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488
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Jeong HJ, Park SW, Kim H, Park SK, Yoon D. Coculture with BJ fibroblast cells inhibits the adipogenesis and lipogenesis in 3T3-L1 cells. Biochem Biophys Res Commun 2010; 392:520-5. [PMID: 20096664 DOI: 10.1016/j.bbrc.2009.12.184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 12/23/2009] [Indexed: 02/03/2023]
Abstract
Mouse or human fibroblasts are commonly used as feeder cells to prevent differentiation in stem or primary cell culture. In the present study, we addressed whether fibroblasts can affect the differentiation of adipocytes. We found that the differentiation of 3T3-L1 preadipocytes was strongly suppressed when the cells were cocultured with human fibroblast (BJ) cells. BrdU incorporation analysis indicated that mitotic clonal expansion, an early event required for 3T3-L1 cell adipogenesis, was not affected by BJ cells. The 3T3-L1 cell expression levels of peroxisome proliferator-activated receptor gamma2, CCAAT/enhancer-binding protein alpha (C/EBPalpha), sterol regulatory element binding protein-1c, and Krüppel-like factor 15, but not those of C/EBPbeta or C/EBPdelta, were decreased by coculture with BJ cells. When mature 3T3-L1 adipocytes were cocultured with BJ cells, their lipid contents were significantly reduced, with decreased fatty acid synthase expression and increased phosphorylated form of acetyl-CoA carboxylase 1. Our data indicate that coculture with BJ fibroblast cells inhibits the adipogenesis of 3T3-L1 preadipocytes and decreases the lipogenesis of mature 3T3-L1 adipocytes.
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Affiliation(s)
- Hyun Jeong Jeong
- Department of Biochemistry, Kwandong University College of Medicine, Gangneung, Gangwondo 210-701, Republic of Korea
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489
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Wu Y, Zhou S, Smas CM. Downregulated expression of the secreted glycoprotein follistatin-like 1 (Fstl1) is a robust hallmark of preadipocyte to adipocyte conversion. Mech Dev 2010; 127:183-202. [PMID: 20043993 DOI: 10.1016/j.mod.2009.12.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 12/14/2009] [Accepted: 12/21/2009] [Indexed: 11/20/2022]
Abstract
Obesity is a public health crisis in the United States. Targeting preadipocyte to adipocyte conversion may be an effective approach to regulate adipose mass. Using differential screening we identified Fstl1, a secreted glycoprotein with roles in immunomodulation, cell growth, cardioprotection, and vascularization, as a "preadipokine". Fstl1 is highly expressed in 3T3-L1 preadipocytes and dramatically downregulated early in their differentiation to adipocytes. Northern blot analysis of murine tissues reveals white adipose tissue (WAT), lung and heart as primary sites of Fstl1 transcript expression. In WAT, Fstl1 transcript is restricted to the preadipocyte-containing stromal-vascular cell population. Time course studies in multiple adipogenesis models reveal downregulation of Fstl1 is a hallmark of white and brown adipocyte conversion. By Western blot, we show culture media of 3T3-L1 preadipocytes contains high levels of Fstl1 protein that rapidly decline in adipocyte conversion. Moreover, we observe a correlation between preadipocyte phenotype and Fstl1 expression in that TNFalpha-mediated de-differentiation of 3T3-L1 adipocytes is accompanied by re-expression of Fstl1 transcript and protein. Treatment of 3T3-L1 preadipocytes with a panel of 18 hormones and other agents revealed the demethylating agent 5-aza-cytidine decreases Fstl1 transcript and protein levels by approximately 90%. Furthermore, of 10 additional preadipocyte-expressed genes analyzed we find Pref-1, Col1A1, Sca-1/Ly6a, Lox and Thbs2, are also downregulated by 5-aza-cytidine. Using luciferase reporter constructs containing 791 or 3922 bp of the Fstl1 5' flanking region, we determine negative transcriptional regulation by Kruppel-like factor 15. Together, our data suggest downregulation of Fstl1 expression may be an important feature of preadipocyte to adipocyte conversion.
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Affiliation(s)
- Yu Wu
- Department of Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, University of Toledo College of Medicine, Toledo, OH 43614, USA
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490
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Kawaji A, Ohnaka Y, Osada S, Nishizuka M, Imagawa M. Gelsolin, an Actin Regulatory Protein, is Required for Differentiation of Mouse 3T3-L1 Cells into Adipocytes. Biol Pharm Bull 2010; 33:773-9. [DOI: 10.1248/bpb.33.773] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Atsuko Kawaji
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Yuki Ohnaka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Shigehiro Osada
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Makoto Nishizuka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Masayoshi Imagawa
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
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491
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Kawaji A, Nishizuka M, Osada S, Imagawa M. TC10-Like/TC10.BETA.Long Regulates Adipogenesis by Controlling Mitotic Clonal Expansion. Biol Pharm Bull 2010; 33:404-9. [DOI: 10.1248/bpb.33.404] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Atsuko Kawaji
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Makoto Nishizuka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Shigehiro Osada
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Masayoshi Imagawa
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
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492
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Stankov MV, Schmidt RE, Behrens GMN. Impact of stimulatory pathways on adipogenesis and HIV-therapy associated lipoatrophy. Exp Biol Med (Maywood) 2009; 234:1484-92. [PMID: 19934369 DOI: 10.3181/0907-rm-205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE Current understanding of adipogenesis derives mainly from studies with in vitro cell culture systems with divergent experimental requirements. We aimed to investigate the discrepancy between the anti-adipogenic effects of the HIV protease-inhibitor indinavir (IDV) in vitro and the lack of evidence that IDV inhibits adipogenesis in humans. DESIGN AND METHODS We studied cell viability and adipogenesis in murine 3T3-F442A, 3T3-L1 and primary human subcutaneous preadipocytes (phsPA). Differentiation was studied after activation of the established four signalling pathways in different combinations. We analyzed CCAAT/enhancer-binding protein (C/EBP) alpha and peroxisome proliferator-activated receptor (PPAR) gamma expression and triacylglyceride accumulation. Cells were exposed to IDV at concentrations around therapeutic C(max) levels and higher (10 muM and 20 muM) for up to 30 days. RESULTS Under insulin and fetal calf serum (FCS) input, IDV inhibited 3T3-F442A differentiation, an effect that was partially rescued by the addition of 3-isobutyl-1-methylxanthine (IBMX) stimulation. Combined stimulation with FCS, insulin, dexamethasone (DEX) and IBMX led to normal 3T3-L1 differentiation even in the presence of IDV. However, omission of IBMX rendered this cell line sensitive to IDV's anti-adipogenic effects. Differentiation of phsPA requiring complete adipogenic stimulation was not affected by IDV presence. CONCLUSIONS Our data suggest that the potency of IDV to impair differentiation under partial stimulation disappears when all of the differentiation pathways are activated. Such compensatory mechanisms might be responsible for the inability of the drug to affect adipogenesis in vivo.
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Affiliation(s)
- Metodi V Stankov
- Clinic for Immunology and Rheumatology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
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493
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Wang M, Wang JJ, Li J, Park K, Qian X, Ma JX, Zhang SX. Pigment epithelium-derived factor suppresses adipogenesis via inhibition of the MAPK/ERK pathway in 3T3-L1 preadipocytes. Am J Physiol Endocrinol Metab 2009; 297:E1378-87. [PMID: 19808909 PMCID: PMC2793046 DOI: 10.1152/ajpendo.00252.2009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We previously reported that circulating levels of pigment epithelium-derived factor (PEDF), a newly identified adipokine, are increased in patients with type 2 diabetes, correlating with body mass index. However, the role of PEDF in adipogenesis remains elusive. In the present study, we have investigated the effects and mechanisms of PEDF on adipocyte differentiation in 3T3-L1 preadipocytes. Differentiation of 3T3-L1 preadipocytes was induced in the presence or absence of human recombinant PEDF protein. The effects of PEDF on adipogenic gene expression, mitotic clonal expansion (MCE), and MAPK activation were investigated. Physiological concentrations of human PEDF protein inhibited adipocyte differentiation, evidenced by decreased lipid accumulation, downregulation of adipocyte markers, and inhibition of master adipogenic transcription factors such as C/EBP-alpha and PPARgamma. The antiadipogenic effects of PEDF were observed only when PEDF was added to the cells on day 0, but not on day 3 during differentiation, suggesting that PEDF targets some early adipogenic events. Similarly, overexpression of PEDF by adenovirus attenuated adipocyte differentiation. Further studies revealed that PEDF, or U-0126, a specific MAPK/ERK inhibitor, sequentially inhibited the early activation of ERK and MCE. Moreover, PEDF attenuated expression and the phosphorylation of C/EBP-beta at Thr(188), an essential step for transcriptional activation of C/EBP-beta. In addition, PEDF expression was decreased significantly in the first 24 h during adipocyte differentiation, suggesting that downregulation of PEDF may be essential for the initiation of MCE and adipogenesis. We conclude that PEDF inhibits adipogenesis in 3T3-L1 preadipocytes partially because of inhibition of the MAPK/ERK signaling pathway and MCE.
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Affiliation(s)
- Min Wang
- Harold Hamm Oklahoma Diabetes Center and Section of Endocrinology and Diabetes, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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494
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Yamada T, Kawakami SI, Nakanishi N. Effects of dietary roughage levels on the expression of adipogenic transcription factors in Wagyu steers. Meat Sci 2009; 83:775-81. [DOI: 10.1016/j.meatsci.2009.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 05/01/2009] [Accepted: 08/10/2009] [Indexed: 10/20/2022]
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495
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Park YK, Park H. Prevention of CCAAT/enhancer-binding protein beta DNA binding by hypoxia during adipogenesis. J Biol Chem 2009; 285:3289-99. [PMID: 19940121 DOI: 10.1074/jbc.m109.059212] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Upon exposure to adipogenesis-inducing hormones, confluent 3T3-L1 preadipocytes express C/EBPbeta (CCAAT/enhancer binding protein beta). Early induced C/EBPbeta is inactive but, after a lag period, acquires its DNA-binding capability by sequential phosphorylation. During this period, preadipocytes pass the G(1)/S checkpoint synchronously. Thr(188) of C/EBPbeta is phosphorylated initially to prime the factor for subsequent phosphorylation at Ser(184) or Thr(179) by GSK3beta, which translocates into the nuclei during the G(1)/S transition. Many events take place during the G(1)/S transition, including reduction in p27(Kip1) protein levels, retinoblastoma (Rb) phosphorylation, GSK3beta nuclear translocation, and C/EBPbeta binding to target promoters. During hypoxia, hypoxia-inducible factor-1alpha (HIF-1alpha) is stabilized, thus maintaining expression of p27(Kip1), which inhibits Rb phosphorylation. Even under normoxic conditions, constitutive expression of p27(Kip1) blocks the nuclear translocation of GSK3beta and DNA binding capability of C/EBPbeta. Hypoxia also blocks nuclear translocation of GSK3beta and DNA binding capability of C/EBPbeta in HIF-1alpha knockdown 3T3-L1 cells that fail to induce p27(Kip1). Nonetheless, under hypoxia, these cells can block Rb phosphorylation and the G(1)/S transition. Altogether, these findings suggest that hypoxia prevents the nuclear translocation of GSK3beta and the DNA binding capability of C/EBPbeta by blocking the G(1)/S transition through HIF-1alpha-dependent induction of p27(Kip1) and an HIF-1alpha/p27-independent mechanism.
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Affiliation(s)
- Young-Kwon Park
- Department of Life Science, University of Seoul, Siripdae-gil 13, Dongdaemun-gu, Seoul 130-743, Republic of Korea
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496
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Loo LH, Lin HJ, Singh DK, Lyons KM, Altschuler SJ, Wu LF. Heterogeneity in the physiological states and pharmacological responses of differentiating 3T3-L1 preadipocytes. ACTA ACUST UNITED AC 2009; 187:375-84. [PMID: 19948481 PMCID: PMC2779244 DOI: 10.1083/jcb.200904140] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A systems biology–based analysis shows that differentiating adipocytes look very different at the single-cell level and form distinct cellular subpopulations. Increases in key components of adipogenesis and lipolysis pathways correlate at the population-averaged level during adipogenesis. However, differentiating preadipocytes are highly heterogeneous in cellular and lipid droplet (LD) morphologies, and the degree to which individual cells follow population-averaged trends is unclear. In this study, we analyze the molecular heterogeneity of differentiating 3T3-L1 preadipocytes using immunofluorescence microscopy. Unexpectedly, we only observe a small percentage of cells with high simultaneous expression of markers for adipogenesis (peroxisome proliferator-activated receptor γ [PPARγ], CCAAT/enhancer-binding protein α, and adiponectin) and lipid accumulation (hormone-sensitive lipase, perilipin A, and LDs). Instead, we identify subpopulations of cells with negatively correlated expressions of these readouts. Acute perturbation of adipocyte differentiation with PPARγ agonists, forskolin, and fatty acids induced subpopulation-specific effects, including redistribution of the percentage of cells in observed subpopulations and differential expression levels of PPARγ. Collectively, our results suggested that heterogeneity observed during 3T3-L1 adipogenesis reflects a dynamic mixture of subpopulations with distinct physiological states.
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Affiliation(s)
- Lit-Hsin Loo
- Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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497
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Anti-obesity effect of sulfated glucosamine by AMPK signal pathway in 3T3-L1 adipocytes. Food Chem Toxicol 2009; 47:2401-6. [DOI: 10.1016/j.fct.2009.06.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 05/14/2009] [Accepted: 06/04/2009] [Indexed: 11/18/2022]
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498
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Hu Y, Davies GE. Berberine increases expression of GATA-2 and GATA-3 during inhibition of adipocyte differentiation. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2009; 16:864-873. [PMID: 19403287 DOI: 10.1016/j.phymed.2009.03.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 01/26/2009] [Accepted: 03/11/2009] [Indexed: 05/27/2023]
Abstract
It is known that a number of transcription factors are key regulators in the complex process of adipocyte differentiation including peroxisome proliferator activated receptor gamma (PPARgamma) and the CCAAT enhancer binding protein alpha (C/EBPalpha). Studies have demonstrated that in pre-adipocyte 3T3-L1 cells constitutive expression of the DNA binding proteins GATA-2 and GATA-3 results in protein/protein interactions with C/EBPalpha resulting in down regulation of PPARgamma and subsequent suppressed adipocyte differentiation with cells trapped at the pre-adipocyte stage. Thus it appears that GATA-2 and GATA-3 are of critical importance in regulating adipocyte differentiation through molecular interactions with PPARgamma and C/EBPalpha. Recent reports suggest that berberine, an isoquinoline derivative alkaloid isolated from many medicinal herbs prevents differentiation of 3T3-L1 cells via a down regulation of PPARgamma and C/EBPalpha expression. The aim of this study was to determine the effect of berberine on GATA-2 and 3 gene and protein expression levels during differentiation of 3T3-L1 cells. MTT (Methylthiazolyldiphenyl-tetrazolium bromide) was used to detect the cytotoxic effects of berberine on the viability of 3T3-L1 cells during proliferation and differentiation. Differentiation of 3T3-L1 cells was monitored by Oil Red O staining and RT-PCR of PPARgamma and C/EBPalpha and the expression of GATA-2 and 3 was determined by RT-PCR and Western Blot. Results show that following treatment with 8microM berberine the mRNA and protein expression levels of GATA-2 and 3 were elevated and accompanied by inhibited adipocyte differentiation. These results may lead to the use of berberine to target the induction of specific genes such as GATA-2 and GATA-3 which affect adipocyte differentiation.
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Affiliation(s)
- Y Hu
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007, USA
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499
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Zhang L, Paddon C, Lewis MD, Grennan-Jones F, Ludgate M. Gsalpha signalling suppresses PPARgamma2 generation and inhibits 3T3L1 adipogenesis. J Endocrinol 2009; 202:207-15. [PMID: 19460852 PMCID: PMC2710974 DOI: 10.1677/joe-09-0099] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Since TSH receptor (TSHR) expression increases during adipogenesis and signals via cAMP/phospho-cAMP-response element binding protein (CREB), reported to be necessary and sufficient for adipogenesis, we hypothesised that TSHR activation would induce preadipocyte differentiation. Retroviral vectors introduced constitutively active TSHR (TSHR*) into 3T3L1 preadipocytes; despite increased cAMP (RIA) and phospho-CREB (western blot) there was no spontaneous adipogenesis (assessed morphologically, using oil red O and QPCR measurement of adipogenesis markers). We speculated that Gbetagamma signalling may be inhibitory but failed to induce adipogenesis using activated Gsalpha (gsp*). Inhibition of phosphodiesterases did not promote adipogenesis in TSHR* or gsp* populations. Furthermore, differentiation induced by adipogenic medium with pioglitazone was reduced in TSHR* and abolished in gsp* expressing 3T3L1 cells. TSHR* and gsp* did not inactivate PPARgamma (PPARG as listed in the HUGO database) by phosphorylation but expression of PPARgamma1 was reduced and PPARgamma2 undetectable in gsp*. FOXO1 phosphorylation (required to inactivate this repressor of adipogenesis) was lowest in gsp* despite the activation of AKT by phosphorylation. PROF is a mediator that facilitates FOXO1 phosphorylation by phospho-Akt. Its transcript levels remained constantly low in the gsp* population. In most measurements, the TSHR* cells were between the gsp* and control 3T3L1 preadipocytes. The enhanced down-regulation of PREF1 (adipogenesis inhibitor) permits retention of some adipogenic potential in the TSHR* population. We conclude that Gsalpha signalling impedes FOXO1 phosphorylation and thus inhibits PPARgamma transcription and the alternative promoter usage required to generate PPARgamma2, the fat-specific transcription factor necessary for adipogenesis.
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Zhou Y, Wang D, Zhu Q, Gao X, Yang S, Xu A, Wu D. Inhibitory effects of A-769662, a novel activator of AMP-activated protein kinase, on 3T3-L1 adipogenesis. Biol Pharm Bull 2009; 32:993-8. [PMID: 19483304 DOI: 10.1248/bpb.32.993] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
AMP-activated protein kinase (AMPK) is a central player in glucose and lipid metabolism while its role in adipocyte differentiation remains obscure. A-769662, a novel activator of AMPK, has been implicated to reduce body weight gain and decrease liver and plasma triglyceride levels via increasing fatty acid oxidation and reducing fatty acid synthesis in vivo. In this study, we examined the effects of A-769662 on adipocyte differentiation using 3T3-L1 cells. We found that A-769662 significantly inhibited 3T3-L1 differentiation via down-regulation of adipogenesis-related transcription factors and adipogenic markers. The inhibitory effect mainly occurred at the early phase of differentiation through inhibition of mitotic clonal expansion (MCE), which was essential for adipogenesis. A-769662 also decreased cell viability of differentiating and mature 3T3-L1 adipocytes. Moreover, treatment of differentiating 3T3-L1 cells with A-769662 resulted in AMPK over-activation, which led to an increased phosphorylation and inactivation of acetyl-CoA carboxylase (ACC), an important enzyme for the synthesis and usage of fatty acids. Taken together, these results suggest that A-769662 inhibits 3T3-L1 adipogenic differentiation in several ways and therefore may be a promising compound for the treatment of obesity.
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Affiliation(s)
- Yi Zhou
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
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