101
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Shan T, Liu W, Kuang S. Fatty acid binding protein 4 expression marks a population of adipocyte progenitors in white and brown adipose tissues. FASEB J 2012; 27:277-87. [PMID: 23047894 DOI: 10.1096/fj.12-211516] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Adipose tissues regulate metabolism, reproduction, and life span. The development and growth of adipose tissue are due to increases of both adipocyte cell size and cell number; the latter is mediated by adipocyte progenitors. Various markers have been used to identify either adipocyte progenitors or mature adipocytes. The fatty acid binding protein 4 (FABP4), commonly known as adipocyte protein 2 (aP2), has been extensively used as a marker for differentiated adipocytes. However, whether aP2 is expressed in adipogenic progenitors is controversial. Using Cre/LoxP-based cell lineage tracing in mice, we have identified a population of aP2-expressing progenitors in the stromal vascular fraction (SVF) of both white and brown adipose tissues. The aP2-lineage progenitors reside in the adipose stem cell niche and express adipocyte progenitor markers, including CD34, Sca1, Dlk1, and PDGFRα. When isolated and grown in culture, the aP2-expressing SVF cells proliferate and differentiate into adipocytes upon induction. Conversely, ablation of the aP2 lineage greatly reduces the adipogenic potential of SVF cells. When grafted into wild-type mice, the aP2-lineage progenitors give rise to adipose depots in recipient mice. Therefore, the expression of aP2 is not limited to mature adipocytes, but also marks a pool of undifferentiated progenitors associated with the vasculature of adipose tissues. Our finding adds to the repertoire of adipose progenitor markers and points to a new regulator of adipose plasticity.
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Affiliation(s)
- Tizhong Shan
- Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA
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102
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Appelbe OK, Yevtodiyenko A, Muniz-Talavera H, Schmidt JV. Conditional deletions refine the embryonic requirement for Dlk1. Mech Dev 2012; 130:143-59. [PMID: 23059197 DOI: 10.1016/j.mod.2012.09.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 09/13/2012] [Accepted: 09/28/2012] [Indexed: 12/21/2022]
Abstract
Numerous studies have implicated Delta-like 1 (DLK1), a transmembrane protein that shares homology with Notch ligands, in embryonic growth and differentiation. Dlk1 expression is widespread, though not ubiquitous, during early development, but is confined to a few specific cell types in adults. Adult Dlk1-expressing tissues include the Insulin-producing β-cells of the pancreas and the Growth hormone-producing somatotrophs of the pituitary gland. Previously generated Dlk1 null mice (Dlk1(Sul-pat)), display a partially penetrant neonatal lethality and a complex pattern of developmental and adult phenotypes. Here we describe the generation of a conditional Dlk1 mouse line (Dlk1(flox)) to facilitate cell type-specific deletion of the Dlk1 gene, providing a powerful system to explore each aspect of the Dlk1 null phenotype. Four tissue-specific Cre mouse lines were used to produce individual Dlk1 deletions in pancreatic β-cells, pituitary somatotrophs and the endothelial cells of the embryo and placenta, key candidates for the Dlk1 phenotype. Contrary to expectations, all of these conditional mice were fully viable, and none recapitulated any aspect of the Dlk1(Sul-pat) null mice. Dlk1 expression is therefore not essential for the normal development of β-cells, somatotrophs and endothelial cells, and the tissues responsible for the Dlk1 null phenotype remain to be identified. Dlk1(flox) mice will continue to provide an important tool for further research into the function of Dlk1.
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Affiliation(s)
- Oliver K Appelbe
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue, Chicago, IL 60607, USA.
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103
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Pérusse L, Rankinen T, Zuberi A, Chagnon YC, Weisnagel SJ, Argyropoulos G, Walts B, Snyder EE, Bouchard C. The Human Obesity Gene Map: The 2004 Update. ACTA ACUST UNITED AC 2012; 13:381-490. [PMID: 15833932 DOI: 10.1038/oby.2005.50] [Citation(s) in RCA: 212] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This paper presents the eleventh update of the human obesity gene map, which incorporates published results up to the end of October 2004. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTLs) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2004, 173 human obesity cases due to single-gene mutations in 10 different genes have been reported, and 49 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 166 genes which, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 221. The number of human obesity QTLs derived from genome scans continues to grow, and we have now 204 QTLs for obesity-related phenotypes from 50 genome-wide scans. A total of 38 genomic regions harbor QTLs replicated among two to four studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably with 358 findings of positive associations with 113 candidate genes. Among them, 18 genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, >600 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful publications and genomic and other relevant sites can be found at http://obesitygene.pbrc.edu.
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Affiliation(s)
- Louis Pérusse
- Division of Kinesiology, Department of Social and Preventive Medicine, Faculty of Medicine, Laval University, Sainte-Foy, Québec, Canada
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104
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Koistinen HA, Forsgren M, Wallberg-Henriksson H, Zierath JR. Insulin Action on Expression of Novel Adipose Genes in Healthy and Type 2 Diabetic Subjects. ACTA ACUST UNITED AC 2012; 12:25-31. [PMID: 14742839 DOI: 10.1038/oby.2004.5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Adipose tissue secretes several molecules that may participate in metabolic cross-talk to other insulin-sensitive tissues. Thus, adipose tissue is a key endocrine organ that regulates insulin sensitivity in other peripheral insulin target tissues. We have studied the expression and acute insulin regulation of novel genes expressed in adipose tissue that are implicated in the control of whole body insulin sensitivity. RESEARCH METHODS AND PROCEDURES Expression of adiponectin, c-Cbl-associated protein (CAP), 11-beta hydroxysteroid dehydrogenase type 1 (11beta-HSD-1), and sterol regulatory element binding protein (SREBP)-1c was determined in subcutaneous adipose tissue from type 2 diabetic and age- and BMI-matched healthy men by real-time polymerase chain reaction analysis. RESULTS Expression of adiponectin, CAP, 11beta-HSD-1, and SREBP-1c was similar between healthy and type 2 diabetic subjects. Insulin infusion for 3 hours did not affect expression of CAP, 11beta-HSD-1, or adiponectin mRNA in either group. However, insulin infusion increased SREBP-1c expression by 80% in healthy, but not in type 2 diabetic, subjects. DISCUSSION Our results provide evidence that insulin action on SREBP-1c is dysregulated in adipose tissue from type 2 diabetic subjects. Impaired insulin regulation on gene expression of select targets in adipose tissue may contribute to the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Heikki A Koistinen
- Department of Surgical Sciences, Karolinska Institute, Stockholm, Sweden.
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105
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Abstract
Adipose tissue is an important site for lipid storage, energy homeostasis, and whole-body insulin sensitivity. It is important to understand the mechanisms involved in adipose tissue development and function, which can be regulated by the endocrine actions of various peptide and steroid hormones. Recent studies have revealed that white and brown adipocytes can be derived from distinct precursor cells. This review will focus on transcriptional control of adipogenesis and its regulation by several endocrine hormones. The general functions and cellular origins of adipose tissue and how the modulation of adipocyte development pertains to metabolic disease states will also be considered.
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106
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Andries A, Niemeier A, Støving RK, Abdallah BM, Wolf AM, Hørder K, Kassem M. Serum levels of fetal antigen 1 in extreme nutritional States. ISRN ENDOCRINOLOGY 2012; 2012:592648. [PMID: 22844611 PMCID: PMC3403450 DOI: 10.5402/2012/592648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 05/22/2012] [Indexed: 11/23/2022]
Abstract
Objective. Recent data suggest that fetal antigen (FA1) is linked to disorders of body weight. Thus, we measured FA1 serum levels in two extreme nutritional states of morbid obesity (MO) and anorexia nervosa (AN) and monitored its response to weight changes. Design. FA1 and insulin serum concentrations were assessed in a cross-sectional study design at defined time points after gastric restrictive surgery for 25 MO patients and 15 women with AN. Results. Absolute FA1 serum levels were within the assay normal range and were not different between the groups at baseline. However, the ratio of FA1/BMI was significantly higher in AN. FA1 was inversely correlated with BMI before and after weight change in AN, but not in MO patients. In addition, MO patients displayed a significant concomitant decrease of FA1 and insulin with the first 25% of EWL, while in AN patients a significant increase of FA1 was observed in association with weight gain. Conclusion. FA1 is a sensitive indicator of metabolic adaptation during weight change. While FA1 serum levels in humans generally do not correlate with BMI, our results suggest that changes in FA1 serum levels reflect changes in adipose tissue turnover.
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Affiliation(s)
- Alin Andries
- KMEB laboratory, Department of Endocrinology and Center for Eating Disorders, Odense University Hospital, 5000 Odense, Denmark
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107
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Murphy SK, Huang Z, Hoyo C. Differentially methylated regions of imprinted genes in prenatal, perinatal and postnatal human tissues. PLoS One 2012; 7:e40924. [PMID: 22808284 PMCID: PMC3396645 DOI: 10.1371/journal.pone.0040924] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 06/15/2012] [Indexed: 12/11/2022] Open
Abstract
Epigenetic plasticity in relation to in utero exposures may mechanistically explain observed differences in the likelihood of developing common complex diseases including hypertension, diabetes and cardiovascular disease through the cumulative effects of subtle alterations in gene expression. Imprinted genes are essential mediators of growth and development and are characterized by differentially methylated regulatory regions (DMRs) that carry parental allele-specific methylation profiles. This theoretical 50% level of methylation provides a baseline from which endogenously- or exogenously-induced deviations in methylation can be detected. We quantified DNA methylation at imprinted gene DMRs in a large panel of human conceptal tissues, in matched buccal cell specimens collected at birth and at one year of age, and in the major cell fractions of umbilical cord blood to assess the stability of methylation at these regions. DNA methylation was measured using validated pyrosequencing assays at seven DMRs regulating the IGF2/H19, DLK1/MEG3, MEST, NNAT and SGCE/PEG10 imprinted domains. DMR methylation did not significantly differ for the H19, MEST and SGCE/PEG10 DMRs across all conceptal tissues analyzed (ANOVA p>0.10). Methylation differences at several DMRs were observed in tissues from brain (IGF2 and MEG3-IG DMRs), liver (IGF2 and MEG3 DMRs) and placenta (both DLK1/MEG3 DMRs and NNAT DMR). In most infants, methylation profiles in buccal cells at birth and at one year of age were comparable, as was methylation in the major cell fractions of umbilical cord blood. Several infants showed temporal deviations in methylation at multiple DMRs. Similarity of inter-individual and intra-individual methylation at some, but not all of the DMRs analyzed supports the possibility that methylation of these regions can serve as useful biosensors of exposure.
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Affiliation(s)
- Susan K Murphy
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina, United States of America.
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108
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Abstract
In mammals there are two types of adipocytes with opposing functions. Brown adipocytes are characterized by a high number of mitochondria and are specialized for heat production (thermogenesis), expressing thermogenic genes such as UCP1 (uncoupling protein 1). White adipocytes, on the other hand, store energy. Although many key regulators in the differentiation of white adipocytes have been established, our current knowledge on the same proteins in brown adipogenesis is lagging behind. One example is Pref-1 (pre-adipocyte factor-1), which maintains white pre-adipocytes in an undifferentiated state, but is only poorly characterized in the brown pre-adipocyte lineage. In this issue of the Biochemical Journal, Armengol et al. now shed new light on the role and regulation of Pref-1 in brown pre-adipocytes. First, Pref-1 specifically inhibits the thermogenic gene programme in brown pre-adipocytes. Secondly, they identified the transcription factor C/EBPδ (CCAAT/enhancer-binding protein δ) as a direct positive regulator of Pref-1 expression, whereas this protein does not fulfil this role in white adipogenesis. Taken together, these findings indicate that specific manipulation of brown adipocyte differentiation and/or function without interfering with their white adipocyte counterparts may be possible, which may open up new therapeutic ways to combat obesity-associated health problems.
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109
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Pref-1 in brown adipose tissue: specific involvement in brown adipocyte differentiation and regulatory role of C/EBPδ. Biochem J 2012; 443:799-810. [PMID: 22324440 DOI: 10.1042/bj20111714] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pref-1 (pre-adipocyte factor-1) is known to play a central role in regulating white adipocyte differentiation, but the role of Pref-1 in BAT (brown adipose tissue) has not been analysed. In the present study we found that Pref-1 expression is high in fetal BAT and declines progressively after birth. However, Pref-1-null mice showed unaltered fetal development of BAT, but exhibited signs of over-activation of BAT thermogenesis in the post-natal period. In C/EBP (CCAAT/enhancer-binding protein) α-null mice, a rodent model of impaired fetal BAT differentiation, Pref-1 was dramatically overexpressed, in association with reduced expression of the Ucp1 (uncoupling protein 1) gene, a BAT-specific marker of thermogenic differentiation. In brown adipocyte cell culture models, Pref-1 was mostly expressed in pre-adipocytes and declined with brown adipocyte differentiation. The transcription factor C/EBPδ activated the Pref-1 gene transcription in brown adipocytes, through binding to the proximal promoter region. Accordingly, siRNA (small interfering RNA)-induced C/EBPδ knockdown led to reduced Pref-1 gene expression. This effect is consistent with the observed overexpression of C/EBPδ in C/EBPα-null BAT and high expression of C/EBPδ in brown pre-adipocytes. Dexamethasone treatment of brown pre-adipocytes suppressed Pref-1 down-regulation occurring throughout the brown adipocyte differentiation process, increased the expression of C/EBPδ and strongly impaired expression of the thermogenic markers UCP1 and PGC-1α [PPARγ (peroxisome-proliferator-activated receptor γ) co-activator-α]. However, it did not alter normal fat accumulation or expression of non-BAT-specific genes. Collectively, these results specifically implicate Pref-1 in controlling the thermogenic gene expression program in BAT, and identify C/EBPδ as a novel transcriptional regulator of Pref-1 gene expression that may be related to the specific role of glucocorticoids in BAT differentiation.
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110
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Berry DC, DeSantis D, Soltanian H, Croniger CM, Noy N. Retinoic acid upregulates preadipocyte genes to block adipogenesis and suppress diet-induced obesity. Diabetes 2012; 61:1112-21. [PMID: 22396202 PMCID: PMC3331760 DOI: 10.2337/db11-1620] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Accepted: 01/17/2012] [Indexed: 12/22/2022]
Abstract
Retinoic acid (RA) protects mice from diet-induced obesity. The activity is mediated in part through activation of the nuclear receptors RA receptors (RARs) and peroxisome proliferator-activated receptor β/δ and their associated binding proteins cellular RA binding protein type II (CRABP-II) and fatty acid binding protein type 5 in adipocytes and skeletal muscle, leading to enhanced lipid oxidation and energy dissipation. It was also reported that RA inhibits differentiation of cultured preadipocytes. However, whether the hormone suppresses adipogenesis in vivo and how the activity is propagated remained unknown. In this study, we show that RA inhibits adipocyte differentiation by activating the CRABP-II/RARγ path in preadipose cells, thereby upregulating the expression of the adipogenesis inhibitors Pref-1, Sox9, and Kruppel-like factor 2 (KLF2). In turn, KLF2 induces the expression of CRABP-II and RARγ, further potentiating inhibition of adipocyte differentiation by RA. The data also indicate that RA suppresses adipogenesis in vivo and that the activity significantly contributes to the ability of the hormone to counteract diet-induced obesity.
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Affiliation(s)
- Daniel C. Berry
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - David DeSantis
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Hooman Soltanian
- Department of Plastic Surgery, Case Medical Center, Cleveland, Ohio
| | - Colleen M. Croniger
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Noa Noy
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio
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111
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Mitterberger MC, Lechner S, Mattesich M, Kaiser A, Probst D, Wenger N, Pierer G, Zwerschke W. DLK1(PREF1) is a negative regulator of adipogenesis in CD105⁺/CD90⁺/CD34⁺/CD31⁻/FABP4⁻ adipose-derived stromal cells from subcutaneous abdominal fat pats of adult women. Stem Cell Res 2012; 9:35-48. [PMID: 22640926 DOI: 10.1016/j.scr.2012.04.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 04/04/2012] [Accepted: 04/06/2012] [Indexed: 12/20/2022] Open
Abstract
The main physiological function of adipose-derived stromal/progenitor cells (ASC) is to differentiate into adipocytes. ASC are most likely localized at perivascular sites in adipose tissues and retain the capacity to differentiate into multiple cell types. Although cell surface markers for ASC have been described, there is no complete consensus on the antigen expression pattern that will precisely define these cells. DLK1(PREF1) is an established marker for mouse adipocyte progenitors which inhibits adipogenesis. This suggests that DLK1(PREF1) could be a useful marker to characterize human ASC. The DLK1(PREF1) status of human ASC is however unknown. In the present study we isolated ASC from the heterogeneous stromal vascular fraction of subcutaneous abdominal fat pats of adult women. These cells were selected by their plastic adherence and expanded to passage 5. The ASC were characterized as relatively homogenous cell population with the capacity to differentiate in vitro into adipocytes, chondrocytes, and osteoblasts and the immunophenotype CD105⁺/CD90⁺/CD34⁺/CD31⁻/FABP4⁻. The ASC were positive for DLK1(PREF1) which was well expressed in proliferating and density arrested cells but downregulated in the course of adipogenic differentiation. To investigate whether DLK1(PREF1) plays a role in the regulation of adipogenesis in these cells RNAi-mediated knockdown experiments were conducted. Knockdown of DLK1(PREF1) in differentiating ASC resulted in a significant increase of the expression of the adipogenic key regulator PPARγ2 and of the terminal adipogenic differentiation marker FABP4. We conclude that DLK1(PREF1) is well expressed in human ASC and acts as a negative regulator of adipogenesis. Moreover, DLK1(PREF1) could be a functional marker contributing to the characterization of human ASC.
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Affiliation(s)
- Maria C Mitterberger
- Department of Cell Metabolism and Differentiation Research, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
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112
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KAVÁLKOVÁ P, DOSTÁLOVÁ I, HALUZÍKOVÁ D, TRACHTA P, HANUŠOVÁ V, LACINOVÁ Z, PAPEŽOVÁ H, DOMLUVILOVÁ D, ZIKÁN V, HALUZÍK M. Preadipocyte Factor-1 Concentrations in Patients With Anorexia Nervosa: the Influence of Partial Realimentation. Physiol Res 2012; 61:153-9. [DOI: 10.33549/physiolres.932163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Preadipocyte factor-1 (Pref-1) is a member of epidermal growth-factor like family of proteins that regulates adipocyte and osteoblast differentiation. Experimental studies suggest that circulating Pref-1 levels may be also involved in the regulation of lipid and glucose metabolism and energy homeostasis. We hypothesized that alterations in Pref-1 levels may contribute to the ethiopathogenesis of anorexia nervosa or its underlying metabolic abnormalities. We measured Pref-1 concentrations and other hormonal, biochemical and anthropometric parameters in eighteen patients with anorexia nervosa and sixteen healthy women and studied the influence of partial realimentation of anorexia nervosa patients on these parameters. The mean duration of realimentation period was 46±2 days. At baseline, anorexia nervosa patients had significantly decreased body mass index, body weight, body fat content, fasting glucose, serum insulin, TSH, free T4, leptin and total protein. Partial realimentation improved these parameters. Baseline serum Pref-1 levels did not significantly differ between anorexia nervosa and control group (0.26±0.02 vs. 0.32±0.05 ng/ml, p=0.295) but partial realimentation significantly increased circulating Pref-1 levels (0.35±0.04 vs. 0.26±0.02 ng/ml, p<0.05). Post-realimentation Pref-1 levels significantly positively correlated with the change of body mass index after realimentation (r=0.49, p<0.05). We conclude that alterations in Pref-1 are not involved in the ethiopathogenesis of anorexia nervosa but its changes after partial realimentation could be involved in the regulation of adipose tissue expansion after realimentation.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - M. HALUZÍK
- Third Department of Medicine, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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113
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de Zegher F, Díaz M, Sebastiani G, Martín-Ancel A, Sánchez-Infantes D, López-Bermejo A, Ibáñez L. Abundance of circulating preadipocyte factor 1 in early life. Diabetes Care 2012; 35:848-9. [PMID: 22338099 PMCID: PMC3308291 DOI: 10.2337/dc11-1990] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Soluble preadipocyte factor 1 (Pref-1) inhibits adipocyte differentiation. We tested whether circulating levels of soluble Pref-1 are higher in smaller fetuses. RESEARCH DESIGN AND METHODS We performed longitudinal assessments of circulating Pref-1 in infants born appropriate for gestational age (AGA) or small for gestational age (SGA) and also in late-gestational women and in newborns on days 2 and 3. RESULTS At birth, Pref-1 levels were ~100-fold higher than in adults, being in SGA fetuses ~50% higher than in AGA fetuses. By age 4 months, Pref-1 had reached near-adult levels and the original AGA versus SGA difference had disappeared. Pref-1 levels were low in late-gestational women and were still elevated in newborns. CONCLUSIONS Pref-1 is abundantly present in the fetus, is higher in SGA than in AGA fetuses, and is likely to be of fetal origin. We speculate that Pref-1 in early life contributes to variation in postnatal adipocyte numbers, in the subsequent expandability of adipose tissue, and thus in the susceptibility to diabetes in later life.
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Affiliation(s)
- Francis de Zegher
- Department of Woman and Child, University of Leuven, Leuven, Belgium
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114
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Fujioka K, Kajita K, Wu Z, Hanamoto T, Ikeda T, Mori I, Okada H, Yamauchi M, Uno Y, Morita H, Nagano I, Takahashi Y, Ishizuka T. Dehydroepiandrosterone reduces preadipocyte proliferation via androgen receptor. Am J Physiol Endocrinol Metab 2012; 302:E694-704. [PMID: 22234368 DOI: 10.1152/ajpendo.00112.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Several studies have suggested that both testosterone and dehydroepiandrosterone (DHEA) have weight-reducing and antidiabetic effects, especially in rodent studies; however, the precise mechanism of their action remains unclear. Here, we investigated the effect of DHEA on cell growth in adipose tissue. The appearance of senescence-associated β-galactosidase in stromal vascular fraction (SVF) isolated from Otsuka Long-Evans Tokushima fatty rats, an animal model of inherent obese type 2 diabetes, was prevented by DHEA administration. Next, the effects of DHEA and testosterone were compared in vivo and in vitro to evaluate whether these hormones influence cell growth in adipose tissue. Both DHEA and testosterone reduced body weight and epididymal fat weight equivalently when administered for 4 wk. To assess the effect of DHEA and testosterone on cell growth in adipose tissue, 5-bromo-2'-deoxyuridine (BrdU) uptake by SVF was measured. Quantification analysis of BrdU uptake by examining DNA isolated from each SVF revealed that treatment with DHEA and testosterone reduced cell replication. These results indicated that DHEA- and testosterone-induced decreased adiposity was associated with reduced SVF growth. Incubation with DHEA and testosterone equally decreased BrdU uptake by 3T3-L1 preadipocytes. Pretreatment with the androgen receptor (AR) inhibitor flutamide, but not the estrogen receptor inhibitor fulvestrant, abolished these effects. Knockdown of AR with siRNA also inhibited DHEA-induced decreases in BrdU uptake. These results suggest that DHEA-induced growth suppression of preadipocytes is mediated via AR. Therefore, both DHEA and testosterone similarly decrease adipocyte growth possibly via a common mechanism.
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Affiliation(s)
- Kei Fujioka
- Dept. of General Internal Medicine, Gifu Univ. Graduate School of Medicine,Yanagido, Gifu, Japan
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115
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Bi P, Kuang S. Meat Science and Muscle Biology Symposium: stem cell niche and postnatal muscle growth. J Anim Sci 2012; 90:924-35. [PMID: 22100594 PMCID: PMC3437673 DOI: 10.2527/jas.2011-4594] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Stem cell niche plays a critical role in regulating the behavior and function of adult stem cells that underlie tissue growth, maintenance, and regeneration. In the skeletal muscle, stem cells, called satellite cells, contribute to postnatal muscle growth and hypertrophy, and thus, meat production in agricultural animals. Satellite cells are located adjacent to mature muscle fibers underneath a sheath of basal lamina. Microenvironmental signals from extracellular matrix mediated by the basal lamina and from the host myofiber both impinge on satellite cells to regulate their activity. Furthermore, several types of muscle interstitial cells, including intramuscular preadipocytes and connective tissue fibroblasts, have recently been shown to interact with satellite cells and actively regulate the growth and regeneration of postnatal skeletal muscles. From this regard, interstitial adipogenic cells are not only important for marbling and meat quality, but also represent an additional cellular component of the satellite cell niche. At the molecular level, these interstitial cells may interact with satellite cells through cell surface ligands, such as delta-like 1 homolog (Dlk1) protein whose overexpression is thought to be responsible for muscle hypertrophy in callipyge sheep. In fact, extracellular Dlk1 protein has been shown to promote the myogenic differentiation of satellite cells. Understanding the cellular and molecular mechanisms within the stem cell niche that regulate satellite cell differentiation and maintain muscle homeostasis may lead to promising approaches to optimizing muscle growth and composition, thus improving meat production and quality.
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Affiliation(s)
- P. Bi
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907
| | - S. Kuang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907
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116
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Falix FA, Aronson DC, Lamers WH, Gaemers IC. Possible roles of DLK1 in the Notch pathway during development and disease. Biochim Biophys Acta Mol Basis Dis 2012; 1822:988-95. [PMID: 22353464 DOI: 10.1016/j.bbadis.2012.02.003] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/18/2012] [Accepted: 02/06/2012] [Indexed: 12/13/2022]
Abstract
The Delta-Notch pathway is an evolutionarily conserved signaling pathway which controls a broad range of developmental processes including cell fate determination, terminal differentiation and proliferation. In mammals, four Notch receptors (NOTCH1-4) and five activating canonical ligands (JAGGED1, JAGGED2, DLL1, DLL3 and DLL4) have been described. The precise function of noncanonical Notch ligands remains unclear. Delta-like 1 homolog (DLK1), the best studied noncanonical Notch ligand, has been shown to act as an inhibitor of Notch signaling in vitro, but its function in vivo is poorly understood. In this review we summarize Notch signaling during development and highlight recent studies in DLK1expression that reveal new insights into its function.
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Affiliation(s)
- Farah A Falix
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
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117
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Abdallah BM, Kassem M. New factors controlling the balance between osteoblastogenesis and adipogenesis. Bone 2012; 50:540-5. [PMID: 21745614 DOI: 10.1016/j.bone.2011.06.030] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 06/20/2011] [Accepted: 06/23/2011] [Indexed: 02/01/2023]
Abstract
The majority of conditions associated with bone loss, including aging, are accompanied by increased marrow adiposity possibly due to shifting of the balance between osteoblast and adipocyte differentiation in bone marrow stromal (skeletal) stem cells (MSC). In order to study the relationship between osteoblastogenesis and adipogenesis in bone marrow, we have characterized cellular models of multipotent MSC as well as pre-osteoblastic and pre-adipocytic cell populations. Using these models, we identified two secreted factors in the bone marrow microenviroment: secreted frizzled-related protein 1 (sFRP-1) and delta-like1 (preadipocyte factor 1) (Dlk1/Pref-1). Both exert regulatory effects on osteoblastogenesis and adipogenesis. Our studies suggest a model for lineage fate determination of MSC that is regulated through secreted factors in the bone marrow microenvironment that mediate a cross-talk between lineage committed cell populations in addition to controlling differentiation choices of multipotent MSC.
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Affiliation(s)
- Basem M Abdallah
- Endocrine Research Laboratory (KMEB), Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark
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118
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Rivero S, Ruiz-García A, Díaz-Guerra MJM, Laborda J, García-Ramírez JJ. Characterization of a proximal Sp1 response element in the mouse Dlk2 gene promoter. BMC Mol Biol 2011; 12:52. [PMID: 22185379 PMCID: PMC3296630 DOI: 10.1186/1471-2199-12-52] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 12/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND DLK2 is an EGF-like membrane protein, closely related to DLK1, which is involved in adipogenesis. Both proteins interact with the NOTCH1 receptor and are able to modulate its activation. The expression of the gene Dlk2 is coordinated with that of Dlk1 in several tissues and cell lines. Unlike Dlk1, the mouse Dlk2 gene and its locus at chromosome 17 are not fully characterized. RESULTS The goal of this work was the characterization of Dlk2 mRNA, as well as the analysis of the mechanisms that control its basal transcription. First, we analyzed the Dlk2 transcripts expressed by several mouse cells lines and tissues, and mapped the transcription start site by 5' Rapid Amplification of cDNA Ends. In silico analysis revealed that Dlk2 possesses a TATA-less promoter containing minimal promoter elements associated with a CpG island, and sequences for Inr and DPE elements. Besides, it possesses six GC-boxes, considered as consensus sites for the transcription factor Sp1. Indeed, we report that Sp1 directly binds to the Dlk2 promoter, activates its transcription, and regulates its level of expression. CONCLUSIONS Our results provide the first characterization of Dlk2 transcripts, map the location of the Dlk2 core promoter, and show the role of Sp1 as a key regulator of Dlk2 transcription, providing new insights into the molecular mechanisms that contribute to the expression of the Dlk2 gene.
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Affiliation(s)
- Samuel Rivero
- Facultad de Medicina/Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Calle Almansa 14, 02006 Albacete, Spain
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119
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Serr J, Suh Y, Lee K. Cloning of comparative gene identification-58 gene in avian species and investigation of its developmental and nutritional regulation in chicken adipose tissue1. J Anim Sci 2011; 89:3490-500. [DOI: 10.2527/jas.2011-3897] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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120
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Zhao LX, Zhao GP, Guo RQ, Zhang D, Li XH, Zhou HM. DNA methylation status in tissues of sheep clones. Reprod Domest Anim 2011; 47:504-12. [PMID: 22039959 DOI: 10.1111/j.1439-0531.2011.01911.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genomic imprinting and DNA methylation play an important role in mammalian development. Many cloned animals showed heterogeneous DNA methylation profiles. However, there are fewer reports in cloned lambs because of a lack of genomic imprinting information. In this study, we investigated DNA methylation patterns in CpG islands and differentially methylated regions of putative imprinted gene Peg10 and imprinted genes Dlk1, Igf2R and H19 in cloned lambs. Five organs from two cloned lambs died shortly after birth and two normal controls were investigated. We observed normal DNA methylation profiles in cloned lambs. The imprinted genes Dlk1, Igf2R and H19 in livers, kidneys, hearts, muscles and lungs of the two cloned lambs exhibited relatively normal DNA methylation, except for Peg10 showing some differences between controls and cloned lambs. Our results indicate that somatic cell nuclear transfer-produced sheep exhibited relatively normal DNA methylation pattern and experienced normal DNA methylation reprogramming at imprinted loci.
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Affiliation(s)
- L X Zhao
- College of Bioengineering, Inner Mongolia Agricultural University, Hohhot, China
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121
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Abdallah BM, Bay-Jensen AC, Srinivasan B, Tabassi NC, Garnero P, Delaissé JM, Khosla S, Kassem M. Estrogen inhibits Dlk1/FA1 production: a potential mechanism for estrogen effects on bone turnover. J Bone Miner Res 2011; 26:2548-51. [PMID: 21681814 PMCID: PMC3778652 DOI: 10.1002/jbmr.444] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have recently identified delta-like 1/fetal antigen 1 (Dlk1/FA1) as a novel regulator of bone mass that functions to mediate bone loss under estrogen deficiency in mice. In this report, we investigated the effects of estrogen (E) deficiency and E replacement on serum (s) levels of Dlk1/FA1 (s-Dlk1FA1) and its correlation with bone turnover markers. s-Dlk1/FA1 and bone turnover markers (serum cross-linked C-telopeptide [s-CTX] and serum osteocalcin) were measured in two cohorts: a group of pre- and postmenopausal women (n = 100) and a group of postmenopausal women, where half had received estrogen-replacement therapy (ERT, n = 166). s-Dlk1/FA1 and s-CTX were elevated in postmenopausal E-deficient women compared with premenopausal E-replete women (both p < 0.001). s-Dlk1/FA1 was correlated with s-CTX (r = 0.30, p < 0.01). ERT in postmenopausal women decreased s-Dlk1/FA1, as well as s-CTX and s-osteoclacin (all p < .0001). Changes in s-Dlk1 were significantly correlated with those observed in s-CTX (r = 0.18, p < 0.05) and s-osteocalcin (r = 0.28, p < 0.001). In conclusion, s-Dlk1/FA1 is influenced by E-deficiency and is correlated with bone turnover. Increased levels of s-Dlk1/FA1 in postmenopausal women may be a mechanism mediating the effects of estrogen deficiency on bone turnover.
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Affiliation(s)
- Basem M Abdallah
- Endocrine Research Laboratory (KMEB), Department of Endocrinology and Metabolism, Odense University Hospital and University of Southern Denmark, Odense, Denmark.
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122
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Gondret F, Riquet J, Tacher S, Demars J, Sanchez MP, Billon Y, Robic A, Bidanel JP, Milan D. Towards candidate genes affecting body fatness at the SSC7 QTL by expression analyses. J Anim Breed Genet 2011; 129:316-24. [PMID: 22775264 DOI: 10.1111/j.1439-0388.2011.00965.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A quantitative trait locus (QTL) affecting fatness in a way opposite to expectations based on breed means was mapped to swine chromosome 7 (SSC7) using crosses between Large White (LW) and Meishan (MS) founders. Defining the molecular fatness trait more explicitly would allow deducing positional candidate genes, for which expression differences must be analysed in experimental populations. First, mRNA levels of genes representing sequential steps in adipogenesis or involved in lipid metabolism were studied in backfat of pigs having homozygous LW(QTL7)/LW(QTL7) or heterozygous LW(QTL7)/MS(QTL7) alleles and considered at two ages. mRNA level of DLK1 expressed in preadipocytes was greater in MS(QTL7)/LW(QTL7) pigs than in homozygous pigs at 28 days. Transcript abundances of CEBPA involved in differentiation, the prolipogenic FASN gene and the adipocyte-specific marker FABP4 were lower in MS(QTL7)/LW(QTL7) pigs compared with LW(QTL7)/LW(QTL7) pigs at 150 days. Because these results suggest a lag time in terminal differentiation associated with the MS allele, seven genes in the QTL interval were deduced as promising candidates for the QTL effect by bioinformatics analysis. Among them, PPARD and CDKN1A had lower expression levels in MS(QTL7)/LW(QTL7) pigs at both ages. Genotype-related differences were observed in mRNA levels of PPARD target genes involved in cell differentiation (FZD7) or fatty acid oxidation (ACADL and ACOX1) at 150 days. These results re-evaluate the potential of PPARD to explain part of variation in pig adiposity.
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Affiliation(s)
- F Gondret
- INRA, UMR1079 Systèmes d'Elevage, Nutrition Animale et Humaine, Domaine de la Prise, Saint Gilles, France.
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123
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Olson LE, Soriano P. PDGFRβ signaling regulates mural cell plasticity and inhibits fat development. Dev Cell 2011; 20:815-26. [PMID: 21664579 DOI: 10.1016/j.devcel.2011.04.019] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 03/09/2011] [Accepted: 04/27/2011] [Indexed: 12/25/2022]
Abstract
Mural cells (pericytes and vascular smooth muscle cells) provide trophic and structural support to blood vessels. Vascular smooth muscle cells alternate between a synthetic/proliferative state and a differentiated/contractile state, but the dynamic states of pericytes are poorly understood. To explore the cues that regulate mural cell differentiation and homeostasis, we have generated conditional knockin mice with activating mutations at the PDGFRβ locus. We show that increased PDGFRβ signaling drives cell proliferation and downregulates differentiation genes in aortic vascular smooth muscle. Increased PDGFRβ signaling also induces a battery of immune response genes in pericytes and mesenchymal cells and inhibits differentiation of white adipocytes. Mural cells are emerging as multipotent progenitors of pathophysiological importance, and we identify PDGFRβ signaling as an important in vivo regulator of their progenitor potential.
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Affiliation(s)
- Lorin E Olson
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA.
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124
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Wang MM. Notch signaling and Notch signaling modifiers. Int J Biochem Cell Biol 2011; 43:1550-62. [PMID: 21854867 DOI: 10.1016/j.biocel.2011.08.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/28/2011] [Accepted: 08/05/2011] [Indexed: 02/07/2023]
Abstract
Originally discovered nearly a century ago, the Notch signaling pathway is critical for virtually all developmental programs and modulates an astounding variety of pathogenic processes. The DSL (Delta, Serrate, LAG-2 family) proteins have long been considered canonical activators of the core Notch pathway. More recently, a wide and expanding network of non-canonical extracellular factors has also been shown to modulate Notch signaling, conferring newly appreciated complexity to this evolutionarily conserved signal transduction system. Here, I review current concepts in Notch signaling, with a focus on work from the last decade elucidating novel extracellular proteins that up- or down-regulate signal potency.
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Affiliation(s)
- Michael M Wang
- Neurology Service, Veterans Administration Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA.
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125
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Obesity, metabolic syndrome, and adipocytes. J Lipids 2011; 2011:721686. [PMID: 21811683 PMCID: PMC3146987 DOI: 10.1155/2011/721686] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 05/25/2011] [Accepted: 05/30/2011] [Indexed: 01/02/2023] Open
Abstract
Obesity and metabolic syndromes are examples whereby excess energy consumption and energy flux disruptions are causative agents of increased fatness. Because other, as yet elucidated, cellular factors may be involved and because potential treatments of these metabolic problems involve systemic agents that are not adipose depot-specific in their actions, should we be thinking of adipose depot-specific (cellular) treatments for these problems? For sure, whether treating obesity or metabolic syndrome, the characteristics of all adipose depot-specific adipocytes and stromal vascular cells should be considered. The focus of this paper is to begin to align metabolic dysfunctions with specific characteristics of adipocytes.
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126
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Chen L, Qanie D, Jafari A, Taipaleenmaki H, Jensen CH, Säämänen AM, Sanz MLN, Laborda J, Abdallah BM, Kassem M. Delta-like 1/fetal antigen-1 (Dlk1/FA1) is a novel regulator of chondrogenic cell differentiation via inhibition of the Akt kinase-dependent pathway. J Biol Chem 2011; 286:32140-9. [PMID: 21724852 DOI: 10.1074/jbc.m111.230110] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Delta-like 1 (Dlk1, also known as fetal antigen-1, FA1) is a member of Notch/Delta family that inhibits adipocyte and osteoblast differentiation; however, its role in chondrogenesis is still not clear. Thus, we overexpressed Dlk1/FA1 in mouse embryonic ATDC5 cells and tested its effects on chondrogenic differentiation. Dlk1/FA1 inhibited insulin-induced chondrogenic differentiation as evidenced by reduction of cartilage nodule formation and gene expression of aggrecan, collagen Type II and X. Similar effects were obtained either by using Dlk1/FA1-conditioned medium or by addition of a purified, secreted, form of Dlk1 (FA1) directly to the induction medium. The inhibitory effects of Dlk1/FA1 were dose-dependent and occurred irrespective of the chondrogenic differentiation stage: proliferation, differentiation, maturation, or hypertrophic conversion. Overexpression or addition of the Dlk1/FA1 protein to the medium strongly inhibited the activation of Akt, but not the ERK1/2, or p38 MAPK pathways, and the inhibition of Akt by Dlk1/FA1 was mediated through PI3K activation. Interestingly, inhibition of fibronectin expression by siRNA rescued the Dlk1/FA1-mediated inhibition of Akt, suggesting interaction of Dlk1/FA1 and fibronectin in chondrogenic cells. Our results identify Dlk1/FA1 as a novel regulator of chondrogenesis and suggest Dlk1/FA1 acts as an inhibitor of the PI3K/Akt pathways that leads to its inhibitory effects on chondrogenesis.
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Affiliation(s)
- Li Chen
- Molecular Endocrinology Laboratory, Odense University Hospital, University of Southern Denmark, Odense DK-5000, Denmark
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127
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Sánchez-Solana B, Nueda ML, Ruvira MD, Ruiz-Hidalgo MJ, Monsalve EM, Rivero S, García-Ramírez JJ, Díaz-Guerra MJM, Baladrón V, Laborda J. The EGF-like proteins DLK1 and DLK2 function as inhibitory non-canonical ligands of NOTCH1 receptor that modulate each other's activities. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1153-64. [DOI: 10.1016/j.bbamcr.2011.03.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 02/19/2011] [Accepted: 03/07/2011] [Indexed: 12/23/2022]
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128
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Kluth SM, Buchheiser A, Houben AP, Geyh S, Krenz T, Radke TF, Wiek C, Hanenberg H, Reinecke P, Wernet P, Kögler G. DLK-1 as a marker to distinguish unrestricted somatic stem cells and mesenchymal stromal cells in cord blood. Stem Cells Dev 2011; 19:1471-83. [PMID: 20331358 DOI: 10.1089/scd.2010.0070] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In addition to hematopoietic stem cells, cord blood (CB) also contains different nonhematopoietic CD45-, CD34- adherent cell populations: cord blood mesenchymal stromal cells (CB MSC) that behave almost like MSC from bone marrow (BM MSC) and unrestricted somatic stem cells (USSC) that differentiate into cells of all 3 germ layers. Distinguishing between these populations is difficult due to overlapping features such as the immunophenotype or the osteogenic and chondrogenic differentiation pathway. Functional differences in the differentiation potential suggest different developmental stages or different cell populations. Here we demonstrate that the expression of genes and the differentiation toward the adipogenic lineage can discriminate between these 2 populations. USSC, including clonal-derived cells lacking adipogenic differentiation, strongly expressed δ-like 1/preadipocyte factor 1 (DLK-1/PREF1) correlating with high proliferative potential, while CB MSC were characterized by a strong differentiation toward adipocytes correlating with a weak or negative DLK-1/PREF1 expression. Constitutive overexpression of DLK-1/PREF1 in CB MSC resulted in a reduced adipogenic differentiation, whereas silencing of DLK-1 in USSC resulted in adipogenic differentiation.
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Affiliation(s)
- Simone Maria Kluth
- Institute for Transplantation Diagnostics and Cell Therapeutics, Heinrich Heine University Medical Center, Duesseldorf, Germany
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129
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Penesova A, Bunt JC, Bogardus C, Krakoff J. Effect of paternal diabetes on pre-diabetic phenotypes in adult offspring. Diabetes Care 2010; 33:1823-8. [PMID: 20519666 PMCID: PMC2909069 DOI: 10.2337/dc10-0664] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Paternal and maternal type 2 diabetes, exclusive of gestational diabetes, may influence risk factors in the offspring differently (through possible epigenetic effects of parental diabetes) and are difficult to identify without accurate dates of diagnosis. We aimed to examine a metabolic phenotype in three different groups of offspring to see distinct paternal versus maternal effects. RESEARCH DESIGN AND METHODS We examined body composition and insulin action (M) in nondiabetic subjects and insulin secretion tested via acute insulin response (AIR) in normal glucose-tolerant full-heritage Pima Indian adults categorized by disparate parental diabetes status: 1) offspring of fathers with early-onset diabetes (age <35 years) and nondiabetic mothers (ODF; n = 10), 2) offspring of mothers with early-onset diabetes (age <35 years), not exposed to diabetes in utero with nondiabetic fathers (OMED; n = 11), and 3) a control group of offspring of parents without diabetes until >50 years of age (CON; n = 15). RESULTS ODFs were leaner than CONs and OMEDs (percent of body fat [%BF]: least-squares means adjusted for age and sex [95% CI]: 27.3 [23.3-31.3] in ODFs vs. 35.4 [32.2-38.5] in CONs and 32.4 [28.8-36.1] in OMEDs, P = 0.04). ODFs were more insulin sensitive (had a higher M) than OMEDs or CONs, but not after adjustment for age, sex, and %BF. AIR adjusted for M, age, sex, and %BF was lower in ODFs versus CONs and OMEDs (P < 0.05). CONCLUSIONS Adult ODFs were leaner and had lower early insulin secretion, despite being equally insulin sensitive after adjustment for body fat compared to the other groups, indicating a paternal imprinted effect.
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Affiliation(s)
- Adela Penesova
- Obesity and Diabetes Clinical Research Section, Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Phoenix, Arizona, USA.
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130
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Andersen DC, Jensen CH, Schneider M, Nossent AY, Eskildsen T, Hansen JL, Teisner B, Sheikh SP. MicroRNA-15a fine-tunes the level of Delta-like 1 homolog (DLK1) in proliferating 3T3-L1 preadipocytes. Exp Cell Res 2010; 316:1681-91. [PMID: 20385127 DOI: 10.1016/j.yexcr.2010.04.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 02/28/2010] [Accepted: 04/04/2010] [Indexed: 11/16/2022]
Abstract
Delta like 1 homolog (Dlk1) exists in both transmembrane and soluble molecular forms, and is implicated in cellular growth and plays multiple roles in development, tissue regeneration, and cancer. Thus, DLK1 levels are critical for cell function, and abnormal DLK1 expression can be lethal; however, little is known about the underlying mechanisms. We here report that miR-15a modulates DLK1 levels in preadipocytes thus providing a mechanism for DLK1 regulation that further links it to cell cycle arrest and cancer since miR-15a is deregulated in these processes. In preadipocytes, miR-15a increases with cell density, and peaks at the same stage where membrane DLK1(M) and soluble DLK1(S) are found at maximum levels. Remarkably, miR-15a represses the amount of all Dlk1 variants at the mRNA level but also the level of DLK1(M) protein while it increases the amount of DLK1(S) supporting a direct repression of DLK1 and a parallel effect on the protease that cleaves off the DLK1 from the membrane. In agreement with previous studies, we found that miR-15a represses cell numbers, but additionally, we report that miR-15a also increases cell size. Conversely, anti-miR-15a treatment decreases cell size while increasing cell numbers, scenarios that were completely rescued by addition of purified DLK1(S). Our data thus imply that miR-15a regulates cell size and proliferation by fine-tuning Dlk1 among others, and further emphasize miR-15a and DLK1 levels to play important roles in growth signaling networks.
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Affiliation(s)
- Ditte C Andersen
- Laboratory of Molecular and Cellular Cardiology, Department of Biochemistry, Pharmacology and Genetics, Odense University Hospital, University of Southern Denmark, Winsløwparken 21.3, DK-5000 Odense C, Denmark
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131
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Shin S, Han JY, Lee K. Cloning of avian Delta-like 1 homolog gene: the biallelic expression of Delta-like 1 homolog in avian species. Poult Sci 2010; 89:948-55. [PMID: 20371847 DOI: 10.3382/ps.2009-00572] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Delta-like 1 homolog (Dlk1) is a paternally expressed imprinted gene in mammals, regulating development and differentiation of adipose and muscle. The Dlk1 genes of the quail and turkey were cloned and analyzed in their properties of amino acid sequences, alternative splicing, and genetic distances from other species. In addition, because Dlk1 is located in the cluster of up to 10 imprinted genes in mammals, the genomic structure of the cluster was investigated in the chicken. Furthermore, the imprinting status of the avian Dlk1 gene was also determined here. The numbers of coding sequences of the quail and turkey Dlk1 were the same as chicken Dlk1 in nucleotide (1,161 bp) and amino acid (386 amino acids) sequences. The amino acid similarities were more than 96% with predicted conserved domains including the signal sequence, 6 epidermal growth factor-like domains, and a transmembrane domain. As in the chicken, the alternative splicing of Dlk1 transcripts was not observed in the turkey and quail. Phylogenetic analysis revealed that the chicken and turkey Dlk1 were closer than the chicken and quail. Comparative analysis of the gene clusters containing the Dlk1 gene revealed that Yy1, Wars, Wdr25, Begain, Dlk1, Dio3, and Ppp2r5c were found in the cluster of the chicken genome, but 3 genes (Meg3, Rtl1, and Meg8) between Dlk1 and deiodinase, iodothyronine, type III (Dio3) were not found. Several SNP in the genomic DNA sequences of the fifth exon were identified in chickens and quail. Sequencing analysis of reverse transcription-PCR products of Dlk1 revealed that adipose and muscle from chickens and quail heterozygous for these SNP produce Dlk1 transcripts from both alleles, demonstrating biallelic expression of Dlk1 in the avian species. These results clearly demonstrate that avian Dlk1 is not imprinted and its expression might be regulated in a different manner from mammals.
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Affiliation(s)
- S Shin
- Department of Animal Sciences, The Ohio State University, Columbus 43210, USA
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132
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Cellular retinol-binding protein type I (CRBP-I) regulates adipogenesis. Mol Cell Biol 2010; 30:3412-20. [PMID: 20498279 DOI: 10.1128/mcb.00014-10] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adipogenesis is governed by a well-documented cascade of transcription factors. However, less is known about non-transcription factors that govern early stages of adipogenesis. Here we show that cellular retinol-binding protein type I (CRBP-I), a small cytosolic binding protein for retinol and retinaldehyde, is specifically restricted to preadipocytes in white adipose tissue. The absence of CRBP-I in mice (CRBP-I-KO mice) leads to increased adiposity. Despite increased adiposity, CRBP-I-KO mice remain more glucose tolerant and insulin sensitive during high-fat-diet feeding. 3T3-L1 cells deficient in CRBP-I or mouse embryonic fibroblasts derived from CRBP-I-KO mice had increased adipocyte differentiation and triglyceride (TG) accumulation. This was due to increased expression and activity of PPAR gamma, while other transcription factor pathways in early and late differentiation remained unchanged. Conversely, the overexpression of CRBP-I in 3T3-L1 cells results in decreased TG accumulation. In conclusion, CRBP-I is a cytosolic protein specifically expressed in preadipocytes that regulates adipocyte differentiation in part by affecting PPAR gamma activity.
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Abstract
Pref-1/Dlk1 is made as an epidermal growth factor (EGF) repeat-containing transmembrane protein but is cleaved by tumor necrosis factor alpha converting enzyme (TACE) to generate a biologically active soluble form. Soluble Pref-1 inhibits adipocyte differentiation through the activation of extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) and the subsequent upregulation of Sox9 expression. However, others have implicated Notch in Pref-1 signaling and function. Here, we show that Pref-1 does not interact with, or require, Notch for its function. Instead, we show a direct interaction of Pref-1 and fibronectin via the Pref-1 juxtamembrane domain and fibronectin C-terminal domain. We also show that fibronectin is required for the Pref-1-mediated inhibition of adipocyte differentiation, the activation of ERK/MAPK, and the upregulation of Sox9. Furthermore, disrupting fibronectin binding to integrin by the addition of RGD peptides or by the knockdown of alpha 5 integrin prevents the Pref-1 inhibition of adipocyte differentiation. Pref-1 activates the integrin downstream signaling molecules, FAK and Rac, and ERK activation by Pref-1 is blunted by the knockdown of Rac or by the forced expression of dominant-negative Rac. We conclude that, by interacting with fibronectin, Pref-1 activates integrin downstream signaling to activate MEK/ERK and to inhibit adipocyte differentiation.
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Morganstein DL, Wu P, Mane MR, Fisk NM, White R, Parker MG. Human fetal mesenchymal stem cells differentiate into brown and white adipocytes: a role for ERRalpha in human UCP1 expression. Cell Res 2010; 20:434-44. [PMID: 20101261 PMCID: PMC2848839 DOI: 10.1038/cr.2010.11] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We investigated the ability of fetal mesenchymal stem cells (fMSCs) to differentiate into brown and white adipocytes and compared the expression of a number of marker genes and key regulatory factors. We showed that the expression of key adipocyte regulators and markers during differentiation is similar to that in other human and murine adipocyte models, including induction of PPARgamma2 and FABP4. Notably, we found that the preadipocyte marker, Pref-1, is induced early in differentiation and then declines markedly as the process continues, suggesting that fMSCs first acquire preadipocyte characteristics as they commit to the adipogenic lineage, prior to their differentiation into mature adipocytes. After adipogenic induction, some stem cell isolates differentiated into cells resembling brown adipocytes and others into white adipocytes. Detailed investigation of one isolate showed that the novel brown fat-determining factor PRDM16 is expressed both before and after differentiation. Importantly, these cells exhibited elevated basal UCP-1 expression, which was dependent on the activity of the orphan nuclear receptor ERRalpha, highlighting a novel role for ERRalpha in human brown fat. Thus fMSCs represent a useful in vitro model for human adipogenesis, and provide opportunities to study the stages prior to commitment to the adipocyte lineage. They also offer invaluable insights into the characteristics of human brown fat.
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Affiliation(s)
- DL Morganstein
- Molecular Endocrinology, Institution of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - P Wu
- Experimental Fetal Medicine, Institution of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - M Rosell Mane
- Molecular Endocrinology, Institution of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - NM Fisk
- Experimental Fetal Medicine, Institution of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - R White
- Molecular Endocrinology, Institution of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - MG Parker
- Molecular Endocrinology, Institution of Reproductive and Developmental Biology, Imperial College London, London, UK
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135
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Zhang X, Gejman R, Mahta A, Zhong Y, Rice KA, Zhou Y, Cheunsuchon P, Louis DN, Klibanski A. Maternally expressed gene 3, an imprinted noncoding RNA gene, is associated with meningioma pathogenesis and progression. Cancer Res 2010; 70:2350-8. [PMID: 20179190 DOI: 10.1158/0008-5472.can-09-3885] [Citation(s) in RCA: 267] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Meningiomas are common tumors, representing 15% to 25% of all central nervous system tumors. NF2 gene inactivation on chromosome 22 has been shown as an early event in tumorigenesis; however, few factors underlying tumor growth and progression have been identified. The chromosomal abnormalities of 14q32 are often associated with meningioma pathogenesis and progression; therefore, it has been proposed that an as yet unidentified tumor suppressor is present at this locus. Maternally expressed gene 3 (MEG3) is an imprinted gene located at 14q32 which encodes a noncoding RNA with an antiproliferative function. We found that MEG3 mRNA is highly expressed in normal arachnoidal cells. However, MEG3 is not expressed in the majority of human meningiomas or the human meningioma cell lines IOMM-Lee and CH157-MN. There is a strong association between loss of MEG3 expression and tumor grade. Allelic loss at the MEG3 locus is also observed in meningiomas, with increasing prevalence in higher grade tumors. In addition, there is an increase in CpG methylation within the promoter and the imprinting control region of MEG3 gene in meningiomas. Functionally, MEG3 suppresses DNA synthesis in both IOMM-Lee and CH157-MN cells by approximately 60% in bromodeoxyuridine incorporation assays. Colony-forming efficiency assays show that MEG3 inhibits colony formation in CH157-MN cells by approximately 80%. Furthermore, MEG3 stimulates p53-mediated transactivation in these cell lines. Therefore, these data are consistent with the hypothesis that MEG3, which encodes a noncoding RNA, may be a tumor suppressor gene at chromosome 14q32 involved in meningioma progression via a novel mechanism.
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Affiliation(s)
- Xun Zhang
- Neuroendocrine Unit and Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
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136
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Wang Y, Hudak C, Sul HS. Role of preadipocyte factor 1 in adipocyte differentiation. ACTA ACUST UNITED AC 2010; 5:109-115. [PMID: 20414356 DOI: 10.2217/clp.09.80] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Preadipocyte factor 1 (Pref-1) is an EGF-repeat-containing transmembrane protein that inhibits adipogenesis. The extracellular domain of Pref-1 is cleaved by TNF-α converting enzyme to generate the biologically active soluble form of Pref-1. The role of Pref-1 in adipogenesis has been firmly established by in vitro and in vivo studies. Pref-1 activates ERK/MAPK and upregulates Sox9 expression to inhibit adipocyte differentiation. Sox9 directly binds to the promoter regions of CCAAT/enhancer-binding protein-β and CCAAT/enhancer-binding protein-δ in order to suppress their promoter activities in preventing adipocyte differentiation. Here, we describe the function of Pref-1 in adipocyte differentiation and the recent findings on the mechanisms by which Pref-1 inhibits adipocyte differentiation.
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Affiliation(s)
- Yuhui Wang
- Department of Nutritional Science & Toxicology, University of California, Berkeley, CA 94720, USA, Tel.: +1 510 642 3978, ,
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137
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Miyaoka Y, Tanaka M, Imamura T, Takada S, Miyajima A. A novel regulatory mechanism for Fgf18 signaling involving cysteine-rich FGF receptor (Cfr) and delta-like protein (Dlk). Development 2010; 137:159-67. [PMID: 20023171 DOI: 10.1242/dev.041574] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fibroblast growth factors (FGFs) transduce signals through FGF receptors (FGFRs) and have pleiotropic functions. Besides signal-transducing FGFRs, cysteine-rich FGF receptor (Cfr; Glg1) is also known to bind some FGFs, although its physiological functions remain unknown. In this study, we generated Cfr-deficient mice and found that some of them die perinatally, and show growth retardation, tail malformation and cleft palate. These phenotypes are strikingly similar to those of Fgf18-deficient mice, and we revealed interaction between Cfr and Fgf18 both genetically and physically, suggesting functional cooperation. Consistently, introduction of Cfr facilitated Fgf18-dependent proliferation of Ba/F3 cells expressing Fgfr3c. In addition, we uncovered binding between Cfr and delta-like protein (Dlk), and noticed that Cfr-deficient mice are also similar to Dlk-transgenic mice, indicating that Cfr and Dlk function in opposite ways. Interestingly, we also found that Dlk interrupts the binding between Cfr and Fgf18. Thus, the Fgf18 signaling pathway seems to be finely tuned by Cfr and Dlk for skeletal development. This study reveals a novel regulatory mechanism for Fgf18 signaling involving Cfr and Dlk.
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Affiliation(s)
- Yuichiro Miyaoka
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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138
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Kim J, Choi YS, Lim S, Yea K, Yoon JH, Jun DJ, Ha SH, Kim JW, Kim JH, Suh PG, Ryu SH, Lee TG. Comparative analysis of the secretory proteome of human adipose stromal vascular fraction cells during adipogenesis. Proteomics 2009; 10:394-405. [DOI: 10.1002/pmic.200900218] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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139
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Shin J, Li B, Davis ME, Suh Y, Lee K. Comparative analysis of fatty acid-binding protein 4 promoters: Conservation of peroxisome proliferator-activated receptor binding sites1. J Anim Sci 2009; 87:3923-34. [DOI: 10.2527/jas.2009-2124] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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140
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Serr J, Suh Y, Lee K. Regulation of adipose triglyceride lipase by fasting and refeeding in avian species. Poult Sci 2009; 88:2585-91. [DOI: 10.3382/ps.2009-00265] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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141
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Weinstein LS, Xie T, Qasem A, Wang J, Chen M. The role of GNAS and other imprinted genes in the development of obesity. Int J Obes (Lond) 2009; 34:6-17. [PMID: 19844212 DOI: 10.1038/ijo.2009.222] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genomic imprinting is an epigenetic phenomenon affecting a small number of genes, which leads to differential expression from the two parental alleles. Imprinted genes are known to regulate fetal growth and a 'kinship' or 'parental conflict' model predicts that paternally and maternally expressed imprinted genes promote and inhibit fetal growth, respectively. In this review we examine the role of imprinted genes in postnatal growth and metabolism, with an emphasis on the GNAS/Gnas locus. GNAS is a complex imprinted locus with multiple oppositely imprinted gene products, including the G-protein alpha-subunit G(s)alpha that is expressed primarily from the maternal allele in some tissues and the G(s)alpha isoform XLalphas that is expressed only from the paternal allele. Maternal, but not paternal, G(s)alpha mutations lead to obesity in Albright hereditary osteodystrophy. Mouse studies show that this phenomenon is due to G(s)alpha imprinting in the central nervous system leading to a specific defect in the ability of central melanocortins to stimulate sympathetic nervous system activity and energy expenditure. In contrast mutation of paternally expressed XLalphas leads to opposite metabolic effects in mice. Although these findings conform to the 'kinship' model, the effects of other imprinted genes on body weight regulation do not conform to this model.
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Affiliation(s)
- L S Weinstein
- Signal Transduction Section, National Institute of Diabetes, Digestive, and Kidney Disease, National Institutes of Health, Building 10 Rm 8C101, Bethesda, MD 20892-1752, USA.
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142
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Andersen DC, Jensen L, Schrøder HD, Jensen CH. "The preadipocyte factor" DLK1 marks adult mouse adipose tissue residing vascular cells that lack in vitro adipogenic differentiation potential. FEBS Lett 2009; 583:2947-53. [PMID: 19665021 DOI: 10.1016/j.febslet.2009.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 08/03/2009] [Indexed: 01/22/2023]
Abstract
Delta-like 1 (Dlk1) is expressed in 3T3-L1 preadipocytes and has frequently been referred to as "the" preadipocyte marker, yet the phenotype of DLK1(+) cells in adipose tissue remains undetermined. Herein, we demonstrate that DLK1(+) cells encompass around 1-2% of the adult mouse adipose stromal vascular fraction (SVF). Unexpectedly, the DLK1(+)SVF population was enriched for cells expressing genes generally ascribed to the vascular lineage and did not possess any adipogenic differentiation potential in vitro. Instead, DLK1(+) cells comprised an immediate ability for cobblestone formation, generation of tube-like structures on matrigel, and uptake of Acetylated Low Density-Lipoprotein, all characteristics of endothelial cells. We therefore suggest that DLK1(+)SVF cells are of a vascular origin and not them-selves committed preadipocytes as assumed hitherto.
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143
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Shin J, Velleman S, Latshaw J, Wick M, Suh Y, Lee K. The ontogeny of delta-like protein 1 messenger ribonucleic acid expression during muscle development and regeneration: Comparison of broiler and Leghorn chickens. Poult Sci 2009; 88:1427-37. [DOI: 10.3382/ps.2008-00529] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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144
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Abstract
Preadipocyte factor-1 [Pref-1; also called Dlk1 (Delta-like protein 1)] is made as an epidermal growth factor-repeat containing transmembrane protein that produces a biologically active soluble form by TNF-alpha-converting enzyme (TACE)-mediated cleavage. Soluble Pref-1 activates the MAPK kinase/ERK pathway. In adipose tissue, Pref-1 is specifically expressed in preadipocytes but not in adipocytes and thus is used as a preadipocyte marker. Inhibition of adipogenesis by Pref-1 has been well established in vitro as well as in vivo by ablation and overexpression of Pref-1. SRY (sex determining region Y)-box 9 (Sox9), a transcription factor expressed in preadipocytes to suppress CCAAT enhancer binding protein beta and (C/EBP) delta expression, is required to be down-regulated before adipocyte differentiation can proceed. By activating MAPK kinase/ERK, Pref-1 prevents down-regulation of Sox9, resulting in inhibition of adipogenesis. Furthermore, by inducing Sox9, Pref-1 promotes chondrogenic induction of mesenchymal cells but prevents chondrocyte maturation as well as osteoblast differentiation. Thus, Pref-1 directs multipotent mesenchymal cells toward the chondrogenic lineage but inhibits differentiation into adipocytes as well as osteoblasts and chondrocytes. Pref-1, encoded by an imprinted gene, has also been detected in progenitor cells in various tissues during regeneration and therefore may have a more general role in maintaining cells in an undifferentiated state.
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Affiliation(s)
- Hei Sook Sul
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California 94720, USA.
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145
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Yang H, Youm YH, Sun Y, Rim JS, Galbán CJ, Vandanmagsar B, Dixit VD. Axin expression in thymic stromal cells contributes to an age-related increase in thymic adiposity and is associated with reduced thymopoiesis independently of ghrelin signaling. J Leukoc Biol 2009; 85:928-38. [PMID: 19299626 DOI: 10.1189/jlb.1008621] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The adipocytes are the predominant cell types that constitute the bulk of the thymic microenvironment by the fifth decade of life in healthy humans. An age-related increase in thymic adiposity is associated with reduced thymopoiesis and compromised immune surveillance in the elderly. However, the mechanisms regulating the generation of intrathymic adipocytes during aging remain to be elucidated. Here, we report that the CD45- thymic stromal cells (TSCs) are amenable to adipogenesis. We identified that the Wnt inhibitor axin is expressed in the lymphoid as well as stromal cells of the thymus with increased expression in CD45- TSCs of older mice. Knockdown of axin by RNA interference in CD45- primary TSCs led to a marked reduction in adipogenesis with significantly lower expression of adipogenic transcripts peroxisome proliferator-activated receptor 2 (PPAR), adipocyte fatty acid-binding protein (aP2), and perilipin. Age-related elevated axin expression was increased specifically in thymic fibroblasts and medullary thymic epithelial cells (TECs) but not in the cortical TEC or CD45+ cells. Consistent with a role of axin in promoting thymic adipogenesis, axin expression was also colocalized with lipid-expressing adipogenic cells in aging thymus. The prolongevity intervention, caloric restriction (CR), prevented the age-related increase in axin and the adipogenic cell in the thymus together with increase in thymic output. We have recently demonstrated that CR induces ghrelin, which can partially reverse thymic involution. Here, we show that axin expression is not affected by ablation of ghrelin receptors in aging mice, suggesting a ghrelin-independent mechanism for regulation of axin. Our data are consistent with the hypothesis that blocking the specific proadipogenic signals in the thymus may complement the present approaches to rejuvenate thymic function during aging.
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Affiliation(s)
- Hyunwon Yang
- Laboratory of Neuroendocrine-Immunology, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
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146
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Oh JH, Yang MJ, Yang YS, Park HJ, Heo SH, Lee EH, Song CW, Yoon S. Microarray-based analysis of the lung recovery process after stainless-steel welding fume exposure in Sprague-Dawley rats. Inhal Toxicol 2009; 21:347-73. [PMID: 19235613 DOI: 10.1080/08958370802464281] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Repeated exposure to welding fumes promotes a reversible increase in pulmonary disease risk, but the molecular mechanisms by which welding fumes induce lung injury and how the lung recovers from such insults are unclear. In the present study, pulmonary function and gene-expression profiles in the lung were analyzed by Affymetrix GeneChip microarray after 30 days of consecutive exposure to manual metal arc welding combined with stainless-steel (MMA-SS) welding fumes, and again after 30 days of recovery from MMA-SS fume exposure. In total, 577 genes were identified as being either up-regulated or down-regulated (over twofold changes, p < 0.05) in the lungs of low-dose or high-dose groups. Differentially expressed genes were classified based on a k-means clustering algorithm and biological functions and molecular networks were further analyzed using Ingenuity Pathways Analysis. Among the genes affected by exposure to or recovery from MMA-SS fumes, the transcriptional changes of 13 genes that were highly altered by treatment were confirmed by quantitative real-time PCR. Notably, Mmp12, Cd5l, Ccl7, Cxcl5, and Spp1 related to the immune response were up-regulated only in the exposure group, whereas Trem2, IgG-2a, Igh-1a, and Igh were persistently up-regulated in both the exposure and recovery groups. In addition, several genes that might play a role in the repair process of the lung were up-regulated exclusively in the recovery group. Collectively, these data may help elucidate the molecular mechanism of the recovery process of the lung after welding fume exposure.
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Affiliation(s)
- Jung-Hwa Oh
- Division of Research and Development, Korea Institute of Toxicology, Yuseong, Daejeon, Republic of Korea
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147
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Wong RHF, Chang I, Hudak CSS, Hyun S, Kwan HY, Sul HS. A role of DNA-PK for the metabolic gene regulation in response to insulin. Cell 2009; 136:1056-72. [PMID: 19303849 DOI: 10.1016/j.cell.2008.12.040] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 07/25/2008] [Accepted: 12/19/2008] [Indexed: 10/21/2022]
Abstract
Fatty acid synthase (FAS) is a central enzyme in lipogenesis and transcriptionally activated in response to feeding and insulin signaling. The transcription factor USF is required for the activation of FAS transcription, and we show here that USF phosphorylation by DNA-PK, which is dephosphorylated by PP1 in response to feeding, triggers a switch-like mechanism. Under fasting conditions, USF-1 is deacetylated by HDAC9, causing promoter inactivation. In contrast, feeding induces the recruitment of DNA-PK to USF-1 and its phosphorylation, which then allows recruitment of P/CAF, resulting in USF-1 acetylation and FAS promoter activation. DNA break/repair components associated with USF induce transient DNA breaks during FAS activation. In DNA-PK-deficient SCID mice, feeding-induced USF-1 phosphorylation/acetylation, DNA breaks, and FAS activation leading to lipogenesis are impaired, resulting in decreased triglyceride levels. Our study demonstrates that a kinase central to the DNA damage response mediates metabolic gene activation.
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Affiliation(s)
- Roger H F Wong
- Department of Nutritional Science and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
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148
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Ahmadian M, Duncan RE, Varady KA, Frasson D, Hellerstein MK, Birkenfeld AL, Samuel VT, Shulman GI, Wang Y, Kang C, Sul HS. Adipose overexpression of desnutrin promotes fatty acid use and attenuates diet-induced obesity. Diabetes 2009; 58:855-66. [PMID: 19136649 PMCID: PMC2661591 DOI: 10.2337/db08-1644] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To investigate the role of desnutrin in adipose tissue triacylglycerol (TAG) and fatty acid metabolism. RESEARCH DESIGN AND METHODS We generated transgenic mice overexpressing desnutrin (also called adipose triglyceride lipase [ATGL]) in adipocytes (aP2-desnutrin) and also performed adenoviral-mediated overexpression of desnutrin in 3T3-L1CARDelta1 adipocytes. RESULTS aP2-desnutrin mice were leaner with decreased adipose tissue TAG content and smaller adipocyte size. Overexpression of desnutrin increased lipolysis but did not result in increased serum nonesterified fatty acid levels or ectopic TAG storage. We found increased cycling between diacylglycerol (DAG) and TAG and increased fatty acid oxidation in adipocytes from these mice, as well as improved insulin sensitivity. CONCLUSIONS We show that by increasing lipolysis, desnutrin overexpression causes reduced adipocyte TAG content and attenuation of diet-induced obesity. Desnutrin-mediated lipolysis promotes fatty acid oxidation and re-esterification within adipocytes.
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Affiliation(s)
- Maryam Ahmadian
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
| | - Robin E. Duncan
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
| | - Krista A. Varady
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
| | - Danubia Frasson
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
| | - Marc K. Hellerstein
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
| | - Andreas L. Birkenfeld
- Department of Internal Medicine, Yale University, School of Medicine, New Haven, Connecticut
| | - Varman T. Samuel
- Department of Internal Medicine, Yale University, School of Medicine, New Haven, Connecticut
| | - Gerald I. Shulman
- Department of Internal Medicine, Yale University, School of Medicine, New Haven, Connecticut
| | - Yuhui Wang
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
| | - Chulho Kang
- Department of Molecular and Cell Biology, University of California, Berkeley, California
| | - Hei Sook Sul
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California
- Corresponding author: Hei Sook Sul,
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149
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Lee K, Shin J, Latshaw J, Suh Y, Serr J. Cloning of adipose triglyceride lipase complementary deoxyribonucleic acid in poultry and expression of adipose triglyceride lipase during development of adipose in chickens. Poult Sci 2009; 88:620-30. [DOI: 10.3382/ps.2008-00265] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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150
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Wang Y, Sul HS. Pref-1 regulates mesenchymal cell commitment and differentiation through Sox9. Cell Metab 2009; 9:287-302. [PMID: 19254573 PMCID: PMC2673480 DOI: 10.1016/j.cmet.2009.01.013] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 12/01/2008] [Accepted: 01/30/2009] [Indexed: 01/29/2023]
Abstract
Pref-1 is an EGF repeat-containing transmembrane protein that produces a biologically active soluble form by TACE-mediated cleavage. Although Pref-1 inhibition of adipogenesis has been well established, the specific target(s) of Pref-1 or the Pref-1 function in mesenchymal cell commitment/differentiation are not known. Here, we show that Sox9 downregulation is required for adipocyte differentiation and that Pref-1 inhibits adipocyte differentiation through upregulating Sox9 expression. Sox9 directly binds to the promoter regions of C/EBPbeta and C/EBPdelta to suppress their promoter activity, preventing adipocyte differentiation. Furthermore, we also show that, by inducing Sox9, Pref-1 promotes chondrogenic induction of mesenchymal cells but prevents chondrocyte maturation as well as osteoblast differentiation, with supporting in vivo evidence in Pref-1 null and Pref-1 transgenic mice. Thus, Sox9 is a Pref-1 target, and Pref-1 directs multipotent mesenchymal cells to the chondrogenic lineage but inhibits differentiation into adipocytes as well as osteoblasts and chondrocytes.
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Affiliation(s)
- Yuhui Wang
- Department of Nutritional Science and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
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