1
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Kersten S. The impact of fasting on adipose tissue metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159262. [PMID: 36521736 DOI: 10.1016/j.bbalip.2022.159262] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/20/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Fasting and starvation were common occurrences during human evolution and accordingly have been an important environmental factor shaping human energy metabolism. Humans can tolerate fasting reasonably well through adaptative and well-orchestrated time-dependent changes in energy metabolism. Key features of the adaptive response to fasting are the breakdown of liver glycogen and muscle protein to produce glucose for the brain, as well as the gradual depletion of the fat stores, resulting in the release of glycerol and fatty acids into the bloodstream and the production of ketone bodies in the liver. In this paper, an overview is presented of our current understanding of the effects of fasting on adipose tissue metabolism. Fasting leads to reduced uptake of circulating triacylglycerols by adipocytes through inhibition of the activity of the rate-limiting enzyme lipoprotein lipase. In addition, fasting stimulates the degradation of stored triacylglycerols by activating the key enzyme adipose triglyceride lipase. The mechanisms underlying these events are discussed, with a special interest in insights gained from studies on humans. Furthermore, an overview is presented of the effects of fasting on other metabolic pathways in the adipose tissue, including fatty acid synthesis, glucose uptake, glyceroneogenesis, autophagy, and the endocrine function of adipose tissue.
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Affiliation(s)
- Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition and Health, Wageningen University, the Netherlands.
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2
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Liu P, Wang ZH, Kang SS, Liu X, Xia Y, Chan CB, Ye K. High-fat diet-induced diabetes couples to Alzheimer's disease through inflammation-activated C/EBPβ/AEP pathway. Mol Psychiatry 2022; 27:3396-3409. [PMID: 35546632 PMCID: PMC10032575 DOI: 10.1038/s41380-022-01600-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 04/20/2022] [Accepted: 04/26/2022] [Indexed: 01/21/2023]
Abstract
Diabetes is a risk factor for Alzheimer's disease (AD), which is also called type 3 diabetes with insulin reduction and insulin resistance in AD patient brains. However, the molecular mechanism coupling diabetes to AD onset remains incompletely understood. Here we show that inflammation, associated with obesity and diabetes elicited by high-fat diet (HFD), activates neuronal C/EBPβ/AEP signaling that drives AD pathologies and cognitive disorders. HFD stimulates diabetes and insulin resistance in neuronal Thy1-C/EBPβ transgenic (Tg) mice, accompanied with prominent mouse Aβ accumulation and hyperphosphorylated Tau aggregation in the brain, triggering cognitive deficits. These effects are profoundly diminished when AEP is deleted from C/EBPβ Tg mice. Chronic treatment with inflammatory lipopolysaccharide (LPS) facilitates AD pathologies and cognitive disorders in C/EBPβ Tg but not in wild-type mice, and these deleterious effects were substantially alleviated in C/EBPβ Tg/AEP -/- mice. Remarkably, the anti-inflammatory drug aspirin strongly attenuates HFD-induced diabetes and AD pathologies in neuronal C/EBPβ Tg mice. Therefore, our findings demonstrate that inflammation-activated neuronal C/EBPβ/AEP signaling couples diabetes to AD.
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Affiliation(s)
- Pai Liu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
- Neuroscience Program, Laney Graduate School, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Zhi-Hao Wang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
- Department of Neurology, Renmin Hospital, Wuhan University School of Medicine, Wuhan, Hubei Province, China
| | - Seong Su Kang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Xia Liu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Yiyuan Xia
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Chi-Bun Chan
- School of Biological Sciences, The University of Hong Kong, 6N01 Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong, China
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA.
- Faculty of Life and Health Sciences, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China.
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3
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Xia Y, Qadota H, Wang ZH, Liu P, Liu X, Ye KX, Matheny CJ, Berglund K, Yu SP, Drake D, Bennett DA, Wang XC, Yankner BA, Benian GM, Ye K. Neuronal C/EBPβ/AEP pathway shortens life span via selective GABAnergic neuronal degeneration by FOXO repression. SCIENCE ADVANCES 2022; 8:eabj8658. [PMID: 35353567 PMCID: PMC8967231 DOI: 10.1126/sciadv.abj8658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 02/07/2022] [Indexed: 05/05/2023]
Abstract
The age-related cognitive decline of normal aging is exacerbated in neurodegenerative diseases including Alzheimer's disease (AD). However, it remains unclear whether age-related cognitive regulators in AD pathologies contribute to life span. Here, we show that C/EBPβ, an Aβ and inflammatory cytokine-activated transcription factor that promotes AD pathologies via activating asparagine endopeptidase (AEP), mediates longevity in a gene dose-dependent manner in neuronal C/EBPβ transgenic mice. C/EBPβ selectively triggers inhibitory GABAnergic neuronal degeneration by repressing FOXOs and up-regulating AEP, leading to aberrant neural excitation and cognitive dysfunction. Overexpression of CEBP-2 or LGMN-1 (AEP) in Caenorhabditis elegans neurons but not muscle stimulates neural excitation and shortens life span. CEBP-2 or LGMN-1 reduces daf-2 mutant-elongated life span and diminishes daf-16-induced longevity. C/EBPβ and AEP are lower in humans with extended longevity and inversely correlated with REST/FOXO1. These findings demonstrate a conserved mechanism of aging that couples pathological cognitive decline to life span by the neuronal C/EBPβ/AEP pathway.
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Affiliation(s)
- Yiyuan Xia
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
| | - Hiroshi Qadota
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
| | - Zhi-Hao Wang
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
| | - Pai Liu
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
- Neuroscience program, Laney Graduate School, Emory University, Atlanta, GA 30322, USA
| | - Xia Liu
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
| | - Karen X. Ye
- Emory College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Courtney J. Matheny
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
| | - Ken Berglund
- Department of Neurosurgery, Emory University, Atlanta, GA 30322, USA
| | - Shan Ping Yu
- Department of Anesthesiology, Emory University, Atlanta, GA 30322, USA
| | - Derek Drake
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - David A. Bennett
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, USA
| | - Xiao-Chuan Wang
- Department of Pathophysiology, Key Laboratory of Ministry of Education of Neurological Diseases, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | | | - Guy M. Benian
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA
- Faculty of Life and Health Sciences, Shenzhen Institute of Advanced Technology, Shenzhen, China
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4
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Abstract
Insulin plays an important role during adipogenic differentiation of animal preadipocytes and the maintenance of mature phenotypes. However, its role and mechanism in dedifferentiation of adipocyte remains unclear. This study investigated the effects of insulin on dedifferentiation of mice adipocytes, and the potential mechanisms. The preadipocytes were isolated from the subcutaneous white adipose tissue of wild type (WT), TNFα gene mutant (TNFα-/-), leptin gene spontaneous point mutant (db/db) and TNFα-/-/db/db mice and were then induced for differentiation. Interestingly, dedifferentiation of these adipocytes occurred once removing exogenous insulin from the adipogenic medium. As characteristics of dedifferentiation of the adipocytes, downregulation of adipogenic markers, upregulation of stemness markers and loss of intracellular lipids were observed from the four genotypes. Notably, dedifferentiation was occurring earlier if the insulin signal was blocked. These dedifferentiated cells regained the potentials of the stem cell-like characteristics. There is no significant difference in the characteristics of the dedifferentiation between the adipocytes. Overall, the study provided evidence that insulin plays a negative regulatory role in the dedifferentiation of adipocytes. We also confirmed that both dedifferentiation of mouse adipocytes, and effect of the insulin on this process were independent of the cell genotypes, while it is a widespread phenomenon in the adipocytes.
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Affiliation(s)
- Liguo Zang
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Suchart Kothan
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Yiyi Yang
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Xiangyi Zeng
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Lingmin Ye
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Jie Pan
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan, China
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
- CONTACT Jie Pan College of Life Sciences, Shandong Normal University, 88 East Wenhua Ave. Jinan250014, China
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5
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Zhang L, Shannon CE, Bakewell TM, Abdul-Ghani MA, Fourcaudot M, Norton L. Regulation of ANGPTL8 in liver and adipose tissue by nutritional and hormonal signals and its effect on glucose homeostasis in mice. Am J Physiol Endocrinol Metab 2020; 318:E613-E624. [PMID: 32154742 DOI: 10.1152/ajpendo.00339.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The angiopoietin-like protein (ANGPTL) family represents a promising therapeutic target for dyslipidemia, which is a feature of obesity and type 2 diabetes (T2DM). The aim of the present study was to determine the metabolic role of ANGPTL8 and to investigate its nutritional, hormonal, and molecular regulation in key metabolic tissues. The regulation of Angptl8 gene expression by insulin and glucose was quantified using a combination of in vivo insulin clamp experiments in mice and in vitro experiments in primary and cultured hepatocytes and adipocytes. The role of AMPK signaling was examined, and the transcriptional control of Angptl8 was determined using bioinformatic and luciferase reporter approaches. The metabolism of Angptl8 knockout mice (ANGPTL8-/-) was examined following chow and high-fat diets (HFD). Insulin acutely increased Angptl8 expression in liver and adipose tissue, which involved the CCAAT/enhancer-binding protein (C/EBPβ) transcription factor. In insulin clamp experiments, glucose further enhanced Angptl8 expression in the presence of insulin in adipose tissue. The activation of AMPK signaling antagonized the effect of insulin on Angptl8 expression in hepatocytes and adipocytes. The ANGPTL8-/- mice had improved glucose tolerance and displayed reduced fed and fasted plasma triglycerides. However, there was no change in body weight or steatosis in ANGPTL8-/- mice after the HFD. These data show that ANGPTL8 plays important metabolic roles in mice that extend beyond triglyceride metabolism. The finding that insulin, glucose, and AMPK signaling regulate Angptl8 expression may provide important clues about the distinct function of ANGPTL8 in these tissues.
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Affiliation(s)
- Lu Zhang
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas
| | - Chris E Shannon
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas
| | - Terry M Bakewell
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas
| | | | - Marcel Fourcaudot
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas
| | - Luke Norton
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas
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Kolodziej M, Strauss S, Lazaridis A, Bucan V, Kuhbier JW, Vogt PM, Könneker S. Influence of glucose and insulin in human adipogenic differentiation models with adipose-derived stem cells. Adipocyte 2019; 8:254-264. [PMID: 31280651 PMCID: PMC6768274 DOI: 10.1080/21623945.2019.1636626] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Autologous fat grafting represents an attractive source for tissue engineering applications in the field of reconstructive medicine. However, in adipogenic differentiation protocols for human adipose-derived stem cells, the concentration of glucose and insulin varies considerably. With the intent to gain maximum tissue augmentation, we focused on the late phase of adipogenesis. In this study, we modified the differentiation protocol for adipose-derived stem cells by prolongation of the induction period and the application highly concentrated glucose and insulin. Human adipose-derived stem cells were isolated from subcutaneous depots and differentiated in a standard induction medium for the first two weeks, followed by two weeks with varying glucose and insulin concentrations. Morphological changes assessed using Oil-Red-O staining were examined for corresponding alterations in the expression of the adipogenic markers peroxisome proliferator-activated receptor gamma (PPARγ) and lipoprotein lipase (LPL). Furthermore, glucose and lactate levels in conditioned media were monitored over the period of differentiation. We found high-glucose media increasing the level of lipid accumulation and the size of single droplets whereas insulin significantly showed a dose-dependent negative effect on fat storage. However, whereas high glucose stimulated PPARγ transcription, expression levels in insulin-treated cells remained constant. Results permit assumptions that a high-glucose medium intensifies the degree of differentiation in mature adipocytes providing conditions to promote graft volume while we have identified highly concentrated insulin treatment as an inhibitor of lipid storage in the late adipogenic differentiation.
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Affiliation(s)
- Michaela Kolodziej
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
| | - Sarah Strauss
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
| | - Andrea Lazaridis
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
| | - Vesna Bucan
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
| | - Jörn W. Kuhbier
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
| | - Peter M. Vogt
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
| | - Sören Könneker
- Department of Plastic, Aesthetic, Hand and Reconstructive Surgery, Hannover Medical School, Hanover, Germany
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7
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A comparison of methods for effective differentiation of the frozen-thawed 3T3-L1 cells. Anal Biochem 2018; 568:57-64. [PMID: 30594506 DOI: 10.1016/j.ab.2018.12.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/05/2018] [Accepted: 12/26/2018] [Indexed: 12/20/2022]
Abstract
The differentiation efficiency of 3T3-L1 preadipocytes is an essential factor affecting studies on cellular mechanisms associated with obesity, diabetes, and related disorders. Differentiation of 3T3-L1 cells is commonly induced by an adipogenic cocktail containing insulin, dexamethasone (DEX), and 3-isobutyl-1-methylxanthine (IBMX). However, 3T3-L1 cells after freezing and thawing for many times always have a low differentiation efficiency. To solve this problem, we compared the differentiation efficiency of six commonly used adipogenic cocktails and protocols published in 2017. On this basis, we further compared 18 adipogenic cocktails with 2 μM rosiglitazone added and/or with a prolonged treatment with IBMX. The results revealed that the adipogenic cocktail containing 0.5 mM IBMX, 1 μM DEX, and 10 μg/mL insulin was the most effective for the frozen-thawed 3T3-L1 cells differentiation. Rosiglitazone, and IBMX under a prolonged treatment, could improve the differentiation efficiency of the frozen-thawed 3T3-L1 cells. However, the effect was closely related to concentrations of agents in the adipogenic cocktails.
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8
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Shen L, Li Q, Wang J, Zhao Y, Niu L, Bai L, Shuai S, Li X, Zhang S, Zhu L. miR-144-3p Promotes Adipogenesis Through Releasing C/EBPα From Klf3 and CtBP2. Front Genet 2018; 9:677. [PMID: 30619490 PMCID: PMC6305703 DOI: 10.3389/fgene.2018.00677] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/06/2018] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs), a class of small non-coding RNAs, have been proved as novel and potent regulators of adipogenesis. A previous study has found out that miR-144-3p was a biomarker of type 2 diabetes, but the role of miR-144-3p in regulating adipogenesis was still unclear. In the present study, the expression of miR-144-3p increased in obese mice and during the 3T3-L1 differentiation process. Overexpression of miR-144-3p suppressed the expression of cell cycle regulatory factors and inhibited pre-adipocytes proliferation. Besides, overexpression of miR-144-3p accelerated lipid accumulation in adipocytes and positively regulated adipogenesis, which was also accompanied by increasing the expression of genes related to fatty acid synthesis and decreasing the expression of genes involved in fatty acid oxidation. Furthermore, luciferase activity assays indicated that miR-144-3p directly targeted Klf3 and CtBP2. The process was also confirmed by the mRNA and protein expression of Klf3 and CtBP2, which were suppressed by miR-144-3p. Furthermore, miR-144-3p targeting Klf3/CtBP2 would induce C/EBPα activity by releasing corepressors (Klf3 and CtBP2) from its promoter region. Moreover, we also observed that miR-144-3p could promote adipogenesis in mice injected with miR-144-3p agomir through tail-vein injection. Taken together, these results support that miR-144-3p can facilitate adipogenesis both in vitro and in vivo, which implies that miR-144-3p could be a target for therapeutic intervention in obesity and metabolic syndrome in the future.
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Affiliation(s)
- Linyuan Shen
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Qiang Li
- Sichuan Province General Station of Animal Husbandry, Chengdu, China
| | - Jinyong Wang
- Chongqing Academy of Animal Science, Chongqing, China
| | - Ye Zhao
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Lili Niu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Lin Bai
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Surong Shuai
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Xuewei Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Shunhua Zhang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Li Zhu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
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9
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Flubendiamide Enhances Adipogenesis and Inhibits AMPKα in 3T3-L1 Adipocytes. Molecules 2018; 23:molecules23112950. [PMID: 30424524 PMCID: PMC6278525 DOI: 10.3390/molecules23112950] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/09/2018] [Accepted: 11/11/2018] [Indexed: 12/13/2022] Open
Abstract
Flubendiamide, a ryanoid class insecticide, is widely used in agriculture. Several insecticides have been reported to promote adipogenesis. However, the potential influence of flubendiamide on adipogenesis is largely unknown. The current study was therefore to determine the effects of flubendiamide on adipogenesis utilizing the 3T3-L1 adipocytes model. Flubendiamide treatment not only enhanced triglyceride content in 3T3-L1 adipocytes, but also increased the expression of cytosine-cytosine-adenosine-adenosine-thymidine (CCAAT)/enhancer-binding protein α and peroxisome proliferator-activated receptor gamma-γ, two important regulators of adipocyte differentiation. Moreover, the expression of the most important regulator of lipogenesis, acetyl coenzyme A carboxylase, was also increased after flubendiamide treatment. Further study revealed that 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or A769662, two Adenosine 5′-monophosphate (AMP)-activated protein kinase α activators, subverted effects of flubendiamide on enhanced adipogenesis. Together, these results suggest that flubendiamide promotes adipogenesis via an AMPKα-mediated pathway.
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10
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Bahrami-Nejad Z, Zhao ML, Tholen S, Hunerdosse D, Tkach KE, van Schie S, Chung M, Teruel MN. A Transcriptional Circuit Filters Oscillating Circadian Hormonal Inputs to Regulate Fat Cell Differentiation. Cell Metab 2018; 27:854-868.e8. [PMID: 29617644 PMCID: PMC5889123 DOI: 10.1016/j.cmet.2018.03.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 01/26/2018] [Accepted: 03/17/2018] [Indexed: 12/12/2022]
Abstract
Glucocorticoid and other adipogenic hormones are secreted in mammals in circadian oscillations. Loss of this circadian oscillation pattern correlates with obesity in humans, raising the intriguing question of how hormone secretion dynamics affect adipocyte differentiation. Using live, single-cell imaging of the key adipogenic transcription factors CEBPB and PPARG, endogenously tagged with fluorescent proteins, we show that pulsatile circadian hormone stimuli are rejected by the adipocyte differentiation control system. In striking contrast, equally strong persistent signals trigger maximal differentiation. We identify the mechanism of how hormone oscillations are filtered as a combination of slow and fast positive feedback centered on PPARG. Furthermore, we confirm in mice that flattening of daily glucocorticoid oscillations significantly increases the mass of subcutaneous and visceral fat pads. Together, our study provides a molecular mechanism for why stress, Cushing's disease, and other conditions for which glucocorticoid secretion loses its pulsatility may lead to obesity.
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Affiliation(s)
- Zahra Bahrami-Nejad
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Michael L Zhao
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Stefan Tholen
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Devon Hunerdosse
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Karen E Tkach
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Sabine van Schie
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Mingyu Chung
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Mary N Teruel
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA.
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11
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Kukushkin NV. Taking memory beyond the brain: Does tobacco dream of the mosaic virus? Neurobiol Learn Mem 2018; 153:111-116. [PMID: 29396326 DOI: 10.1016/j.nlm.2018.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 01/05/2018] [Accepted: 01/21/2018] [Indexed: 10/18/2022]
Abstract
Memory is typically defined through animal behavior, but this point of view may limit our understanding of many related processes in diverse biological systems. The concept of memory can be broadened meaningfully by considering it from the perspective of time and homeostasis. On the one hand, this theoretical angle can help explain and predict the behavior of various non-neural systems such as insulin-secreting cells, plants, or signaling cascades. On the other hand, it emphasizes biological continuity between neural phenomena, such as synaptic plasticity, and their evolutionary precursors in cellular signaling.
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Affiliation(s)
- Nikolay V Kukushkin
- Center for Neural Science, New York University, 4 Washington Pl, New York, NY 10003, USA.
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12
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Jahandideh F, Chakrabarti S, Davidge ST, Wu J. Egg white hydrolysate shows insulin mimetic and sensitizing effects in 3T3-F442A pre-adipocytes. PLoS One 2017; 12:e0185653. [PMID: 28972997 PMCID: PMC5626431 DOI: 10.1371/journal.pone.0185653] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/16/2017] [Indexed: 01/19/2023] Open
Abstract
Insulin resistance and inflammation in adipose tissue is a key mechanism underlying metabolic syndrome, a growing health problem characterized by diabetes, obesity and hypertension. Previous work from our research group has demonstrated the potential of egg white ovotransferrin derived bioactive peptides against hypertension, oxidative stress and inflammation in vitro and in vivo. Egg white hydrolysate (EWH) has also shown anti-hypertensive effects in spontaneously hypertensive rats. Given the interplay among hypertension, inflammation, oxidative stress and metabolic syndrome, the objective of the study was to test the EWH on differentiation, insulin signaling and inflammatory responses in 3T3-F442A pre-adipocytes. Our study suggested that EWH could promote adipocyte differentiation as shown by increased lipid accumulation, increased release of adiponectin and upregulation of peroxisome proliferator associated receptor gamma (PPARγ) and CCAAT/ enhancer binding protein alpha (C/EBP-α). In addition to enhanced insulin effects on the upregulation of protein kinase B/Akt phosphorylation, EWH treatment increased extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation to a level similar to that of insulin, indicating insulin sensitizing and mimetic properties of the EWH. EWH further attenuated cytokine induced inflammatory marker; cyclooxygenase -2 (COX-2) by 48.78%, possibly through the AP-1 pathway by down regulating c-Jun phosphorylation in adipocytes. Given the critical role of adipose in the pathogenesis of insulin resistance and metabolic syndrome, EWH may have potential applications in the prevention and management of metabolic syndrome and its complications.
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Affiliation(s)
- Forough Jahandideh
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Subhadeep Chakrabarti
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Sandra T. Davidge
- Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
- Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jianping Wu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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13
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Echinomycin inhibits adipogenesis in 3T3-L1 cells in a HIF-independent manner. Sci Rep 2017; 7:6516. [PMID: 28747725 PMCID: PMC5529514 DOI: 10.1038/s41598-017-06761-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 06/19/2017] [Indexed: 01/08/2023] Open
Abstract
Obesity is a risk factor for many diseases including diabetes, cancer, cardiovascular disease, and chronic kidney disease. Obesity is characterized by the expansion of white adipose tissue (WAT). Hypertrophy and hyperplasia of adipocytes cause tissue hypoxia followed by inflammation and fibrosis. Its trigger, preadipocyte differentiation into mature adipocytes, is finely regulated by transcription factors, signal molecules, and cofactors. We found that echinomycin, a potent HIF-1 inhibitor, completely inhibited adipogenesis in 3T3-L1 WAT preadipocytes by affecting the early phase of mitotic clonal expansion. The dose required to exert the effect was surprisingly low and the time was short. Interestingly, its inhibitory effect was independent of HIF-1 pathways. Time-course DNA microarray analysis of drug-treated and untreated preadipocytes extracted a major transcription factor, CCAAT/enhancer-protein β, as a key target of echinomycin. Echinomycin also inhibited adipogenesis and body weight gain in high fat diet mice. These findings highlight a novel role of echinomycin in suppressing adipocyte differentiation and offer a new therapeutic strategy against obesity and diabetes.
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Annual Wormwood Leaf Inhibits the Adipogenesis of 3T3-L1 and Obesity in High-Fat Diet-Induced Obese Rats. Nutrients 2017; 9:nu9060554. [PMID: 28555033 PMCID: PMC5490533 DOI: 10.3390/nu9060554] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 05/16/2017] [Accepted: 05/23/2017] [Indexed: 12/22/2022] Open
Abstract
Annual wormwood (AW) (Artemisia annua L.) has anti-malarial, anti-bacterial, anti-oxidant, anti-tumour, and anti-inflammatory activities. In the present study, we evaluated the effects of annual wormwood leaves (AWL) on adipocyte differentiation in 3T3-L1 cells and high-fat diet (HFD)-induced obese rats. 3T3-L1 adipocytes and HFD-induced obese rats were treated with AWL, and its effect on gene expression was analyzed using RT-PCR and Western blotting experiments. Treatment with AWL effectively prevented triglyceride accumulation during adipogenesis in a dose-dependent manner. Consistently, AWL suppressed the differentiation of 3T3-L1 preadipocytes into adipocytes through the downregulation of dexamethasone, 3-isobutyl-1- methylxanthine, and insulin (DMI)-induced serine/threonine kinase protein kinase B (PKB/Akt) activation and the expression of adipogenic genes, including the CCAAT/enhancer binding protein-α (C/EBPα) and peroximal proliferator-activated receptor-γ (PPARγ). Moreover, the expression of adipocyte fatty acid-binding protein 4 (aP2), which is a known PPARγ-target gene, was downregulated by AWL treatment. Oral administration of AWL extracts significantly decreased the body weight gain, adipose tissue mass, adipocyte cell size, serum triglyceride (TG), and total cholesterol (TC) levels in HFD-induced obese rats. These results provide novel insight into the molecular mechanisms underlying the anti-obesity effects of AWL that are mediated by the downregulation of the expression of major adipogenic transcription factors, C/EBPα and PPARγ and Akt signalling.
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15
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Go G, Sung JS, Jee SC, Kim M, Jang WH, Kang KY, Kim DY, Lee S, Shin HS. In vitro anti-obesity effects of sesamol mediated by adenosine monophosphate-activated protein kinase and mitogen-activated protein kinase signaling in 3T3-L1 cells. Food Sci Biotechnol 2017; 26:195-200. [PMID: 30263528 DOI: 10.1007/s10068-017-0026-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 09/25/2016] [Accepted: 12/15/2016] [Indexed: 01/10/2023] Open
Abstract
Sesamol is a phenol derivative of sesame oil and a potent anti-oxidant, anti-inflammatory, anti-hepatotoxic, and anti-aging compound. We investigated the effects of sesamol on the molecular mechanisms of adipogenesis in 3T3-L1 preadipocytes. The intracellular lipid accumulation accompanied by increased extracellular release of free glycerol was decreased during differentiation on treating 3T3-L1 with sesamol. Sesamol treatment on 3T3-L1 inhibited adipogenic differentiation by down-regulating adipogenesis-related factors (C/EBPα, PPARγ, and SREBP-1). Lipid accumulation was repressed by decreasing fatty acid synthase and by up-regulating lipolysis-response genes (HSL and LPL). The molecular mechanisms of sesamol-induced inhibition in adipogenesis were mediated by increased levels of phosphorylated adenosine monophosphate-activated protein kinase and its substrate acetyl-CoA carboxylase. Sesamol treatment, in turn, modulated the different members of the mitogenactivated protein kinase family by suppressing phosphorylation of ERK 1/2 and JNK and by increasing the phosphorylation of p38. In summary, sesamol inhibits adipogenic differentiation by reducing phosphorylation levels of ERK 1/2 and JNK while inducing lipolysis by activating p38 and AMPK. Our results demonstrate that the molecular mechanisms of in vitro anti-obesity effects of sesamol are due to the combined effects of preventing both lipid accumulation and adipogenesis.
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Affiliation(s)
- Geon Go
- Department of Life Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Jung-Suk Sung
- Department of Life Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Seung-Cheol Jee
- Department of Life Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Min Kim
- Department of Life Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Won-Hee Jang
- Department of Life Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Kyu-Young Kang
- Department of Biological and Environmental Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Dae-Young Kim
- Department of Biological and Environmental Science, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Sihyoung Lee
- Department of Food Science and Biotechnology, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
| | - Han-Seung Shin
- Department of Food Science and Biotechnology, Dongguk University-Seoul, Goyang, Gyeonggi, 10326 Korea
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Sigumjang (fermented barley bran) water-soluble extracts inhibit the expression of adipogenic and lipogenic regulators in 3T3-L1 adipocytes. Food Sci Biotechnol 2016; 25:1727-1735. [PMID: 30263468 DOI: 10.1007/s10068-016-0264-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/31/2016] [Accepted: 10/07/2016] [Indexed: 10/20/2022] Open
Abstract
Sigumjang prepared from fermented barley bran is a traditional fermented food found only in the Gyeongsang-do area of South Korea. There have been no studies reported to date despite the potential bioactivities of sigumjang. In this study, the anti-obesity activities of sigumjang extracts (SEs) during 3T3-L1 differentiation into adipocytes were investigated. SEs inhibited adipocyte differentiation by suppressing the CCAAT/enhancer binding protein-β and sterol regulatory element binding protein-1c expression in the early stage of differentiation, followed by the suppression of the peroxisome proliferator-activated receptor-γ, CCAAT/enhancer binding protein-α, and adiponectin. These changes in adipogenic markers induced inhibition of lipogenesis via down-regulation of mainly fatty acid synthase, acetyl-CoA carboxylase, fatty acid binding protein 4, and perilipin. These results were more significant in the extract of sigumjang fermented with isolated Bacillus amyloliquefaciens MFST compared to naturally fermented sigumjang group. SEs can be considered as a useful material for developing food with health benefits and anti-obesity properties.
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Trukhachev V, Skripkin V, Kvochko A, Kulichenko A, Kovalev D, Pisarenko S, Volynkina A, Selionova M, Aybazov M, Golovanova N, Yatsyk O, Krivoruchko A. Associations Between Newly Discovered Polymorphisms of the CEBPD GENE LOCUS and Body Parameters in Sheep. Anim Biotechnol 2016; 27:217-22. [PMID: 27565864 DOI: 10.1080/10495398.2016.1168304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
An understanding of what effects particular genes can have on body parameters in productive animals is particularly significant for the process of marker-assisted selection. The gene of transcriptional factor CCAAT/enhancer-binding protein delta (CEBPD gene) is involved in the process of growth in animals and is known to be a promising candidate for use as a genomic marker. The structure of the CEBPD gene locus was determined using NimbleGen sequencing technology (Roche, USA). The effect of polymorphisms, which were identified using the aforementioned technology, was investigated in 30 rams of the Manych Merino sheep breed. Twenty-two single nucleotide polymorphisms (SNP) were detected in the CEBPD gene locus. Significantly, two SNPs, namely, g.315T>G and g.327C>T, have been identified for the first time. It was demonstrated that the complex of linked SNPs, consisting of g.301A>T, g.426T>C, and g.1226T>C, had a negligible effect on body parameters in Manych Merino sheep. Animals with the heterozygous type of SNP g.1142C>T exhibited changes solely in the chest and croup width. The newly discovered SNP g.327C>T was proven to have a negative effect on live weight and body size (p < 0.05) in Manych Merino sheep. Sheep with the heterozygous type of g.562G>A and g.3112C>G SNP complex showed an increase in live weight and dimensions (p < 0.05) compared with those of wild homozygous type. Consequently, SNPs g.327C>T, g.562G>A, and g.3112C>G in the CEBPD gene locus can be successfully used as markers in sheep breeding. Future research will evaluate the influence of the aforementioned SNPs on slaughter indicators for sheep meat production.
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Affiliation(s)
- Vladimir Trukhachev
- a Faculty of Veterinary Medicine , Stavropol State Agrarian University , Stavropol , Russian Federation
| | - Valentin Skripkin
- a Faculty of Veterinary Medicine , Stavropol State Agrarian University , Stavropol , Russian Federation
| | - Andrey Kvochko
- a Faculty of Veterinary Medicine , Stavropol State Agrarian University , Stavropol , Russian Federation
| | | | - Dmitry Kovalev
- b Stavropol Research Anti-plague Institute , Stavropol , Russian Federation
| | - Sergey Pisarenko
- b Stavropol Research Anti-plague Institute , Stavropol , Russian Federation
| | - Anna Volynkina
- b Stavropol Research Anti-plague Institute , Stavropol , Russian Federation
| | - Marina Selionova
- c All-Russian Research Institute Of Sheep and Goat Breeding , Stavropol , Russian Federation
| | - Magomet Aybazov
- c All-Russian Research Institute Of Sheep and Goat Breeding , Stavropol , Russian Federation
| | - Natalia Golovanova
- a Faculty of Veterinary Medicine , Stavropol State Agrarian University , Stavropol , Russian Federation
| | - Olesya Yatsyk
- a Faculty of Veterinary Medicine , Stavropol State Agrarian University , Stavropol , Russian Federation
| | - Alexander Krivoruchko
- a Faculty of Veterinary Medicine , Stavropol State Agrarian University , Stavropol , Russian Federation
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18
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Ko CY, Chang WC, Wang JM. Biological roles of CCAAT/Enhancer-binding protein delta during inflammation. J Biomed Sci 2015; 22:6. [PMID: 25591788 PMCID: PMC4318212 DOI: 10.1186/s12929-014-0110-2] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/25/2014] [Indexed: 01/13/2023] Open
Abstract
CCAAT/enhancer-binding protein delta (CEBPD) belongs to the CCAAT/enhancer-binding protein family, and these proteins function as transcription factors in many biological processes, including cell differentiation, motility, growth arrest, proliferation, cell death, metabolism and immune responses. The functional diversity of CEBPD depends, in part, on the cell type and cellular context, which indicates that CEBPD could interpret a variety of cues to adjust cellular responses in specific situations. Here, we review the regulation of the CEBPD gene and its function in response to inflammatory stimuli. We also address its effects in inflammation-related diseases through a discussion of its recently discovered downstream targets. Regarding to the previous discoveries and new insights in inflammation-associated diseases, suggesting CEBPD could also be a central gene in inflammation. Importantly, the results of this study indicate that the investigation of CEBPD could open a new avenue to help better understand the inflammatory response.
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Affiliation(s)
- Chiung-Yuan Ko
- Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, 11031, Taiwan. .,Center for Neurotrauma and Neuroregeneration, Taipei Medical University, Taipei, 11031, Taiwan.
| | - Wen-Chang Chang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, 11031, Taiwan.
| | - Ju-Ming Wang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, 11031, Taiwan. .,Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan. .,Infectious Disease and Signaling Research Center, National Cheng Kung University, Tainan, 70101, Taiwan. .,Center of Molecular Inflammation, National Cheng Kung University, Tainan, 70101, Taiwan.
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Nishizuka M, Hayashi T, Asano M, Osada S, Imagawa M. KCNK10, a tandem pore domain potassium channel, is a regulator of mitotic clonal expansion during the early stage of adipocyte differentiation. Int J Mol Sci 2014; 15:22743-56. [PMID: 25501330 PMCID: PMC4284734 DOI: 10.3390/ijms151222743] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/10/2014] [Accepted: 11/26/2014] [Indexed: 01/13/2023] Open
Abstract
KCNK10, a member of tandem pore domain potassium channel family, gives rise to leak K+ currents. It plays important roles in stabilizing the negative resting membrane potential and in counterbalancing depolarization. We previously demonstrated that kcnk10 expression is quickly elevated during the early stage of adipogenesis of 3T3-L1 cells and that reduction of kcnk10 expression inhibits adipocyte differentiation. However, the molecular mechanism of KCNK10 in adipocyte differentiation remains unclear. Here we revealed that kcnk10 is induced by 3-isobutyl-1-methylxanthine, a cyclic nucleotide phosphodiesterase inhibitor and a potent inducer of adipogenesis, during the early stage of adipocyte differentiation. We also demonstrated that KCNK10 functions as a positive regulator of mitotic clonal expansion (MCE), a necessary process for terminal differentiation. The reduction of kcnk10 expression repressed the expression levels of CCAAT/enhancer-binding protein β (C/EBPβ) and C/EBPδ as well as the phosphorylation level of Akt during the early phase of adipogenesis. In addition, knockdown of kcnk10 expression suppressed insulin-induced Akt phosphorylation. These results indicate that KCNK10 contributes to the regulation of MCE through the control of C/EBPβ and C/EBPδ expression and insulin signaling.
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Affiliation(s)
- Makoto Nishizuka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan.
| | - Takahiro Hayashi
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan.
| | - Mami Asano
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan.
| | - Shigehiro Osada
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan.
| | - Masayoshi Imagawa
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan.
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20
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Park M, Choi YA, Lee HG, Kim KI, Lim JS, Lee MS, Oh KS, Yang Y. Dephosphorylation of CCAAT/enhancer-binding protein β by protein phosphatase 2A containing B56δ is required at the early time of adipogenesis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:1608-18. [PMID: 25152162 DOI: 10.1016/j.bbalip.2014.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/26/2014] [Accepted: 08/12/2014] [Indexed: 12/11/2022]
Abstract
It is known that protein phosphatase 2A (PP2A) expression is increased in high-fat diet (HFD)-induced obese mice, but the role of PP2A in adipogenesis as well as obesity remains to be addressed. In this study, the role of PP2A in adipogenesis was explored. Preadipocytes were treated with okadaic acid (OA) during adipogenesis and the degree of adipogenesis was determined. The OA treatment blocked adipogenesis at the early time of adipogenesis, but not at the late time. In the early time of adipogenesis, CCAAT/enhancer-binding protein β (C/EBPβ) activation is preceded by the expression of key adipogenic transcription factors including PPARγ and C/EBPα, which function at the late time of adipogenesis, and then C/EBPβ is degraded. However, the inhibition of PP2A by OA treatment sustained phosphorylation of C/EBPβ and delayed its degradation. In turn, PPARγ and C/EBPα activation was altered. Among the various regulatory B56 subunits consisting of PP2A holoenzyme, B56δ was directly bound to C/EBPβ and was responsible for the dephosphorylation of C/EBPβ by PP2A. Taken together, these findings suggest that the phosphorylation of C/EBPβ after hormonal induction has to be inactivated by PP2A containing B56δ at the early time of adipogenesis to allow the completion of adipogenesis.
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Affiliation(s)
- Miyoung Park
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Yeon A Choi
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Hee Gu Lee
- Korea Research Institute of Bioscience and Biotechnology, Daejon 305-333, Republic of Korea
| | - Keun Il Kim
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Jong-Seok Lim
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Myeong-Sok Lee
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Ki-Sook Oh
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Young Yang
- Department of Life Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
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21
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Andrieu T, Fustier P, Alikhani-Koupaei R, Ignatova ID, Guettinger A, Frey FJ, Frey BM. Insulin, CCAAT/enhancer-binding proteins and lactate regulate the human 11β-hydroxysteroid dehydrogenase type 2 gene expression in colon cancer cell lines. PLoS One 2014; 9:e105354. [PMID: 25133511 PMCID: PMC4136812 DOI: 10.1371/journal.pone.0105354] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/23/2014] [Indexed: 01/22/2023] Open
Abstract
11β-Hydroxysteroid dehydrogenases (11beta-HSD) modulate mineralocorticoid receptor transactivation by glucocorticoids and regulate access to the glucocorticoid receptor. The isozyme 11beta-HSD2 is selectively expressed in mineralocorticoid target tissues and its activity is reduced in various disease states with abnormal sodium retention and hypertension, including the apparent mineralocorticoid excess. As 50% of patients with essential hypertension are insulin resistant and hyperinsulinemic, we hypothesized that insulin downregulates the 11beta-HSD2 activity. In the present study we show that insulin reduced the 11beta-HSD2 activity in cancer colon cell lines (HCT116, SW620 and HT-29) at the transcriptional level, in a time and dose dependent manner. The downregulation was reversible and required new protein synthesis. Pathway analysis using mRNA profiling revealed that insulin treatment modified the expression of the transcription factor family C/EBPs (CCAAT/enhancer-binding proteins) but also of glycolysis related enzymes. Western blot and real time PCR confirmed an upregulation of C/EBP beta isoforms (LAP and LIP) with a more pronounced increase in the inhibitory isoform LIP. EMSA and reporter gene assays demonstrated the role of C/EBP beta isoforms in HSD11B2 gene expression regulation. In addition, secretion of lactate, a byproduct of glycolysis, was shown to mediate insulin-dependent HSD11B2 downregulation. In summary, we demonstrate that insulin downregulates HSD11B2 through increased LIP expression and augmented lactate secretion. Such mechanisms are of interest and potential significance for sodium reabsorption in the colon.
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Affiliation(s)
- Thomas Andrieu
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
| | - Pierre Fustier
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
| | - Rasoul Alikhani-Koupaei
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
| | - Irena D. Ignatova
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
| | - Andreas Guettinger
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
| | - Felix J. Frey
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
| | - Brigitte M. Frey
- Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
- * E-mail:
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22
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Ngo S, Li X, O'Neill R, Bhoothpur C, Gluckman P, Sheppard A. Elevated S-adenosylhomocysteine alters adipocyte functionality with corresponding changes in gene expression and associated epigenetic marks. Diabetes 2014; 63:2273-83. [PMID: 24574043 DOI: 10.2337/db13-1640] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Maternal deficiencies in micronutrients affecting one-carbon metabolism before and during pregnancy can influence metabolic status and the degree of insulin resistance and obesity of the progeny in adulthood. Notably, maternal and progeny plasma S-adenosylhomocysteine (SAH) levels are both elevated after vitamin deficiency in pregnancy. Therefore, we investigated whether this key one-carbon cycle intermediate directly affects adipocyte differentiation and function. We found that expansion and differentiation of murine 3T3-L1 preadipocytes in the presence of SAH impaired both basal and induced glucose uptake as well as lipolysis compared with untreated controls. SAH did not alter preadipocyte factor 1 (Dlk1) or peroxisome proliferator-activated receptor-γ 2 (Pparγ2) but significantly reduced expression of CAAT enhancer-binding protein-α (Cebpα), Cebpβ, and retinoid x receptor-α (Rxrα) compared with untreated adipocytes. SAH increased Rxrα methylation on a CpG unit (chr2:27,521,057+, chr2:27,521,049+) and CpG residue (chr2:27,521,080+), but not Cebpβ methylation, relative to untreated adipocytes. Trimethylated histone H3-Lys27 occupancy was significantly increased on Cebpα and Rxrα promoters in SAH-treated adipocytes, consistent with the reduction in gene expression. In conclusion, SAH did not affect adipogenesis per se but altered adipocyte functionality through epigenetic mechanisms, such that they exhibited altered glucose disposal and lipolysis. Our findings implicate micronutrient imbalance in subsequent modulation of adipocyte function.
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Affiliation(s)
- Sherry Ngo
- Developmental Epigenetics Group, Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Xiaoling Li
- Developmental Epigenetics Group, Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Renelle O'Neill
- Developmental Epigenetics Group, Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Chandrakanth Bhoothpur
- Developmental Epigenetics Group, Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Peter Gluckman
- Developmental Epigenetics Group, Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Allan Sheppard
- Developmental Epigenetics Group, Liggins Institute, The University of Auckland, Auckland, New Zealand
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23
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Sayed M, Drummond CA, Evans KL, Haller ST, Liu J, Xie Z, Tian J. Effects of Na/K-ATPase and its ligands on bone marrow stromal cell differentiation. Stem Cell Res 2014; 13:12-23. [PMID: 24793006 DOI: 10.1016/j.scr.2014.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 03/21/2014] [Accepted: 04/05/2014] [Indexed: 12/16/2022] Open
Abstract
Endogenous ligands of Na/K-ATPase have been demonstrated to increase in kidney dysfunction and heart failure. It is also reported that Na/K-ATPase signaling function effects stem cell differentiation. This study evaluated whether Na/K-ATPase activation through its ligands and associated signaling functions affect bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells) differentiation capacity. BMSCs were isolated from male Sprague-Dawley rats and cultured in minimal essential medium alpha (MEM-α) supplemented with 15% Fetal Bovine serum (FBS). The results showed that marinobufagenin (MBG), a specific Na/K-ATPase ligand, potentiated rosiglitazone-induced adipogenesis in these BMSCs. Meanwhile, it attenuated BMSC osteogenesis. Mechanistically, MBG increased CCAAT/enhancer binding protein alpha (C/EBPα) protein expression through activation of an extracellular regulated kinase (ERK) signaling pathway, which leads to enhanced rosiglitazone-induced adipogenesis. Inhibition of ERK activation by U0126 blocks the effect of MBG on C/EBPα expression and on rosiglitazone-induced adipogenesis. Reciprocally, MBG reduced runt-related transcription factor 2 (RunX2) expression, which resulted in the inhibition of osteogenesis induced by β-glycerophosphate/ascorbic acid. MBG also potentiated rosiglitazone-induced adipogenesis in 3T3-L1 cells and in mouse BMSCs. These results suggest that Na/K-ATPase and its signaling functions are involved in the regulation of BMSCs differentiation.
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Affiliation(s)
- Moustafa Sayed
- Department of Medicine, University of Toledo, Toledo, OH, USA
| | | | - Kaleigh L Evans
- Department of Medicine, University of Toledo, Toledo, OH, USA
| | - Steven T Haller
- Department of Medicine, University of Toledo, Toledo, OH, USA
| | - Jiang Liu
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Zijian Xie
- Department of Medicine, University of Toledo, Toledo, OH, USA
| | - Jiang Tian
- Department of Medicine, University of Toledo, Toledo, OH, USA.
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24
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Xiang X, An W, Jiang C, Zhao J, Wang X, Sun G, Li Y, Zhang W. Lipopolysaccharide inhibits the expression of resistin in adipocytes. J Mol Endocrinol 2013; 51:287-99. [PMID: 23969982 DOI: 10.1530/jme-13-0117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Resistin is an adipocytokine leading to insulin resistance. Endotoxin/lipopolysaccharide (LPS) has been reported to decrease the expression of resistin mRNA and protein in both lean and db/db obese mice, although the underlying mechanism remains unclear. Several models such as ex vivo culture of adipose tissues, primary rat adipocytes and 3T3-L1 adipocytes were used to further characterize the effect of LPS on the expression of resistin. LPS attenuated both the resistin mRNA and protein in a time- and dose-dependent manner. In the presence of actinomycin D, LPS failed to reduce the half-life of resistin mRNA, suggesting a transcriptional mechanism. The lipid A fraction is crucial for the inhibition of resistin expression induced by LPS. Pharmacological intervention of c-Jun N-terminal kinase (JNK) reversed the inhibitory effect of LPS. LPS down-regulated CCAAT/enhancer-binding protein α (C/EBP-α; CEBPA) and peroxisome proliferator-activated receptor γ (PPAR-γ; PPARG), while activation of C/EBP-α or PPAR-γ by either over-expressing these transcriptional factors or by rosiglitazone, an agonist of PPAR-γ, blocked the inhibitory effect of LPS on resistin. C/EBP homologous protein (CHOP-10; DDIT3) was up-regulated by LPS, while a CHOP-10 antisense oligonucleotide reversed the decrement of resistin protein induced by LPS. Taken together, these results suggest that LPS inhibits resistin expression through a unique signaling pathway involving toll-like receptor 4, JNK, CHOP-10 and C/EBP-α/PPAR-γ.
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Affiliation(s)
- Xinxin Xiang
- Department of Physiology and Pathophysiology, Peking University Health Science Center; Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing 100191, China Department of Pathology, Central Hospital of Zibo, Zibo 255000, China Division of Medicine, Memorial University of Newfoundland, St John's, Newfoundland, Canada Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA
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Drira R, Sakamoto K. Modulation of adipogenesis, lipolysis and glucose consumption in 3T3-L1 adipocytes and C2C12 myotubes by hydroxytyrosol acetate: A comparative study. Biochem Biophys Res Commun 2013; 440:576-81. [DOI: 10.1016/j.bbrc.2013.09.106] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 09/21/2013] [Indexed: 11/17/2022]
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Effects of Experimental Diabetes on C/EBP Proteins in Rat Hippocampus, Sciatic Nerve and Ganglia. Cell Mol Neurobiol 2013; 33:559-67. [PMID: 23508841 DOI: 10.1007/s10571-013-9924-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 03/08/2013] [Indexed: 02/01/2023]
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Role of C/EBPβ-LAP and C/EBPβ-LIP in early adipogenic differentiation of human white adipose-derived progenitors and at later stages in immature adipocytes. Differentiation 2013; 85:20-31. [DOI: 10.1016/j.diff.2012.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 09/20/2012] [Accepted: 11/26/2012] [Indexed: 12/20/2022]
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Park HJ, Chung BY, Lee MK, Song Y, Lee SS, Chu GM, Kang SN, Song YM, Kim GS, Cho JH. Centipede grass exerts anti-adipogenic activity through inhibition of C/EBPβ, C/EBPα, and PPARγ expression and the AKT signaling pathway in 3T3-L1 adipocytes. Altern Ther Health Med 2012. [PMID: 23181522 PMCID: PMC3584807 DOI: 10.1186/1472-6882-12-230] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Background Centipede grass (CG) originates from China and South America and is reported to contain several C-glycosyl flavones and phenolic constituents, including maysin and luteolin derivatives. This study aimed to investigate, for the first time, the antiobesity activity of CG and its potential molecular mechanism in 3T3-L1 cells. Methods To study the effect of CG on adipogenesis, differentiating 3T3-L1 cells were treated every day with CG at various concentrations (0–100 μg/ml) for six days. Oil-red O staining and triglyceride content assay were performed to determine the lipid accumulation in 3T3-L1 cells. The expression of mRNAs or proteins associated with adipogenesis was measured using RT-PCR and Western blotting analysis. We examined the effect of CG on level of phosphorylated Akt in 3T3-L1 cells treated with CG at various concentration s during adipocyte differentiation. Results Differentiation was investigated with an Oil-red O staining assay using CG-treated 3T3-L1 adipocytes. We found that CG suppressed lipid droplet formation and adipocyte differentiation in 3T3-L1 cells in a dose-dependent manner. Treatment of the 3T3-L1 adipocytes with CG resulted in an attenuation of the expression of adipogenesis-related factors and lipid metabolic genes. The expression of C/EBPα and PPARγ, the central transcriptional regulators of adipogenesis, was decreased by the treatment with CG. The expression of genes involved in lipid metabolism, aP2 were significantly inhibited following the CG treatment. Moreover, the CG treatment down-regulated the phosphorylation levels of Akt and GSK3β. Conclusions Taken collectively, these data indicated that CG exerts antiadipogenic activity by inhibiting the expression of C/EBPβ, C/EBPα, and PPARγ and the Akt signaling pathway in 3T3-L1 adipocytes.
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Kim EJ, Lee DH, Kim HJ, Lee SJ, Ban JO, Cho MC, Jeong HS, Yang Y, Hong JT, Yoon DY. Thiacremonone, a sulfur compound isolated from garlic, attenuates lipid accumulation partially mediated via AMPK activation in 3T3-L1 adipocytes. J Nutr Biochem 2012; 23:1552-8. [PMID: 22405697 DOI: 10.1016/j.jnutbio.2011.10.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 10/01/2011] [Accepted: 10/19/2011] [Indexed: 12/24/2022]
Abstract
Garlic extracts exert anti-cancer and anti-inflammatory effects. However, the anti-adipogenic effect of garlic-derived compounds remains unclear. In this study, we examined the effect of thiacremonone, a sulfur compound isolated from garlic, on adipocyte differentiation using 3T3-L1 cells. We found that thiacremonone significantly inhibited 3T3-L1 differentiation via down-regulation of adipogenesis-related transcription factors and adipogenic markers. The inhibitory effect mainly occurred at the early phase of differentiation in 3T3-L1 cells. There was no cytotoxic effect of thiacremonone in 3T3-L1 cells and treatment of differentiating 3T3-L1 cells with thiacremonone resulted in AMPK activation, which led to an attenuated expression of acetyl CoA carboxylase-1 (ACC-1), an essential enzyme for the synthesis and usage of fatty acids. Moreover, thiacremonone enhanced the mRNA level of carnitine palmitoyltransferase (CPT-1). The modulating effect of thiacremonone on expressions of genes involved in lipolysis was partially abrogated by treatment with compound C, an AMPK inhibitor. Taken together, these results indicated that thiacremonone-induced AMPK activation, inhibition of ACC-1 expression and concomitant recovery of CPT-1 expression resulted in the suppression of intracellular lipid droplet levels, suggesting that thiacremonone may induce reduction of lipid synthesis and increases in fatty acid oxidation partially mediated via AMPK activation. Thiacremonone may be a promising compound for the treatment of obesity.
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Affiliation(s)
- Eun Jin Kim
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Hwayang-dong 1, Gwangjin-gu, Seoul 143-701, Republic of Korea
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Wada T, Ihunnah CA, Gao J, Chai X, Zeng S, Philips BJ, Rubin JP, Marra KG, Xie W. Estrogen sulfotransferase inhibits adipocyte differentiation. Mol Endocrinol 2011; 25:1612-23. [PMID: 21816900 DOI: 10.1210/me.2011-1089] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The estrogen sulfotransferase (EST) is a phase II drug-metabolizing enzyme known to catalyze the sulfoconjugation of estrogens. EST is highly expressed in the white adipose tissue of male mice, but the role of EST in the development and function of adipocytes remains largely unknown. In this report, we showed that EST played an important role in adipocyte differentiation. EST was highly expressed in 3T3-L1 preadipocytes and primary mouse preadipocytes. The expression of EST was dramatically reduced in differentiated 3T3-L1 cells and mature primary adipocytes. Overexpression of EST in 3T3-L1 cells prevented adipocyte differentiation. In contrast, preadipocytes isolated from EST knockout (EST-/-) mice exhibited enhanced differentiation. The inhibitory effect of EST on adipogenesis likely resulted from the sustained activation of ERK1/2 MAPK and inhibition of insulin signaling, leading to a failure of switch from clonal expansion to differentiation. The enzymatic activity of EST was required for the inhibitory effect of EST on adipogenesis, because an enzyme-dead EST mutant failed to inhibit adipocyte differentiation. In vivo, overexpression of EST in the adipose tissue of female transgenic mice resulted in smaller adipocyte size. Taken together, our results suggest that EST functions as a negative regulator of adipogenesis.
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Affiliation(s)
- Taira Wada
- Center for Pharmacogenetics, Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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Ninomiya Y, Sugahara-Yamashita Y, Nakachi Y, Tokuzawa Y, Okazaki Y, Nishiyama M. Development of a rapid culture method to induce adipocyte differentiation of human bone marrow-derived mesenchymal stem cells. Biochem Biophys Res Commun 2010; 394:303-8. [PMID: 20206132 DOI: 10.1016/j.bbrc.2010.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 03/01/2010] [Indexed: 01/14/2023]
Abstract
Human mesenchymal stem cells (hMSCs) derived from bone marrow are multipotent stem cells that can regenerate mesenchymal tissues such as adipose, bone or muscle. It is thought that hMSCs can be utilized as a cell resource for tissue engineering and as human models to study cell differentiation mechanisms, such as adipogenesis, osteoblastogenesis and so on. Since it takes 2-3weeks for hMSCs to differentiate into adipocytes using conventional culture methods, the development of methods to induce faster differentiation into adipocytes is required. In this study we optimized the culture conditions for adipocyte induction to achieve a shorter cultivation time for the induction of adipocyte differentiation in bone marrow-derived hMSCs. Briefly, we used a cocktail of dexamethasone, insulin, methylisobutylxanthine (DIM) plus a peroxisome proliferator-activated receptor gamma agonist, rosiglitazone (DIMRo) as a new adipogenic differentiation medium. We successfully shortened the period of cultivation to 7-8days from 2-3weeks. We also found that rosiglitazone alone was unable to induce adipocyte differentiation from hMSCs in vitro. However, rosiglitazone appears to enhance hMSC adipogenesis in the presence of other hormones and/or compounds, such as DIM. Furthermore, the inhibitory activity of TGF-beta1 on adipogenesis could be investigated using DIMRo-treated hMSCs. We conclude that our rapid new culture method is very useful in measuring the effect of molecules that affect adipogenesis in hMSCs.
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Affiliation(s)
- Yuichi Ninomiya
- Translational Research Center, Saitama International Medical, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1298, Japan
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Soliman GA, Acosta-Jaquez HA, Dunlop EA, Ekim B, Maj NE, Tee AR, Fingar DC. mTOR Ser-2481 autophosphorylation monitors mTORC-specific catalytic activity and clarifies rapamycin mechanism of action. J Biol Chem 2009; 285:7866-79. [PMID: 20022946 DOI: 10.1074/jbc.m109.096222] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) Ser/Thr kinase signals in at least two multiprotein complexes distinguished by their different partners and sensitivities to rapamycin. Acute rapamycin inhibits signaling by mTOR complex 1 (mTORC1) but not mTOR complex 2 (mTORC2), which both promote cell growth, proliferation, and survival. Although mTORC2 regulation remains poorly defined, diverse cellular mitogens activate mTORC1 signaling in a manner that requires sufficient levels of amino acids and cellular energy. Before the identification of distinct mTOR complexes, mTOR was reported to autophosphorylate on Ser-2481 in vivo in a rapamycin- and amino acid-insensitive manner. These results suggested that modulation of mTOR intrinsic catalytic activity does not universally underlie mTOR regulation. Here we re-examine the regulation of mTOR Ser-2481 autophosphorylation (Ser(P)-2481) in vivo by studying mTORC-specific Ser(P)-2481 in mTORC1 and mTORC2, with a primary focus on mTORC1. In contrast to previous work, we find that acute rapamycin and amino acid withdrawal markedly attenuate mTORC1-associated mTOR Ser(P)-2481 in cycling cells. Although insulin stimulates both mTORC1- and mTORC2-associated mTOR Ser(P)-2481 in a phosphatidylinositol 3-kinase-dependent manner, rapamycin acutely inhibits insulin-stimulated mTOR Ser(P)-2481 in mTORC1 but not mTORC2. By interrogating diverse mTORC1 regulatory input, we find that without exception mTORC1-activating signals promote, whereas mTORC1-inhibitory signals decrease mTORC1-associated mTOR Ser(P)-2481. These data suggest that mTORC1- and likely mTORC2-associated mTOR Ser-2481 autophosphorylation directly monitors intrinsic mTORC-specific catalytic activity and reveal that rapamycin inhibits mTORC1 signaling in vivo by reducing mTORC1 catalytic activity.
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Affiliation(s)
- Ghada A Soliman
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109-2200, USA
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Foster KG, Acosta-Jaquez HA, Romeo Y, Ekim B, Soliman GA, Carriere A, Roux PP, Ballif BA, Fingar DC. Regulation of mTOR complex 1 (mTORC1) by raptor Ser863 and multisite phosphorylation. J Biol Chem 2009; 285:80-94. [PMID: 19864431 DOI: 10.1074/jbc.m109.029637] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The rapamycin-sensitive mTOR complex 1 (mTORC1) promotes protein synthesis, cell growth, and cell proliferation in response to growth factors and nutritional cues. To elucidate the poorly defined mechanisms underlying mTORC1 regulation, we have studied the phosphorylation of raptor, an mTOR-interacting partner. We have identified six raptor phosphorylation sites that lie in two centrally localized clusters (cluster 1, Ser(696)/Thr(706) and cluster 2, Ser(855)/Ser(859)/Ser(863)/Ser(877)) using tandem mass spectrometry and generated phosphospecific antibodies for each of these sites. Here we focus primarily although not exclusively on raptor Ser(863) phosphorylation. We report that insulin promotes mTORC1-associated phosphorylation of raptor Ser(863) via the canonical PI3K/TSC/Rheb pathway in a rapamycin-sensitive manner. mTORC1 activation by other stimuli (e.g. amino acids, epidermal growth factor/MAPK signaling, and cellular energy) also promote raptor Ser(863) phosphorylation. Rheb overexpression increases phosphorylation on raptor Ser(863) as well as on the five other identified sites (e.g. Ser(859), Ser(855), Ser(877), Ser(696), and Thr(706)). Strikingly, raptor Ser(863) phosphorylation is absolutely required for raptor Ser(859) and Ser(855) phosphorylation. These data suggest that mTORC1 activation leads to raptor multisite phosphorylation and that raptor Ser(863) phosphorylation functions as a master biochemical switch that modulates hierarchical raptor phosphorylation (e.g. on Ser(859) and Ser(855)). Importantly, mTORC1 containing phosphorylation site-defective raptor exhibits reduced in vitro kinase activity toward the substrate 4EBP1, with a multisite raptor 6A mutant more strongly defective that single-site raptor S863A. Taken together, these data suggest that complex raptor phosphorylation functions as a biochemical rheostat that modulates mTORC1 signaling in accordance with environmental cues.
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Affiliation(s)
- Kathryn G Foster
- Department of Cell and Developmental Biology, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan 48109-2200, USA
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Acosta-Jaquez HA, Keller JA, Foster KG, Ekim B, Soliman GA, Feener EP, Ballif BA, Fingar DC. Site-specific mTOR phosphorylation promotes mTORC1-mediated signaling and cell growth. Mol Cell Biol 2009; 29:4308-24. [PMID: 19487463 PMCID: PMC2715808 DOI: 10.1128/mcb.01665-08] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/15/2008] [Accepted: 05/22/2009] [Indexed: 11/20/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) complex 1 (mTORC1) functions as a rapamycin-sensitive environmental sensor that promotes cellular biosynthetic processes in response to growth factors and nutrients. While diverse physiological stimuli modulate mTORC1 signaling, the direct biochemical mechanisms underlying mTORC1 regulation remain poorly defined. Indeed, while three mTOR phosphorylation sites have been reported, a functional role for site-specific mTOR phosphorylation has not been demonstrated. Here we identify a new site of mTOR phosphorylation (S1261) by tandem mass spectrometry and demonstrate that insulin-phosphatidylinositol 3-kinase signaling promotes mTOR S1261 phosphorylation in both mTORC1 and mTORC2. Here we focus on mTORC1 and show that TSC/Rheb signaling promotes mTOR S1261 phosphorylation in an amino acid-dependent, rapamycin-insensitive, and autophosphorylation-independent manner. Our data reveal a functional role for mTOR S1261 phosphorylation in mTORC1 action, as S1261 phosphorylation promotes mTORC1-mediated substrate phosphorylation (e.g., p70 ribosomal protein S6 kinase 1 [S6K1] and eukaryotic initiation factor 4E binding protein 1) and cell growth to increased cell size. Moreover, Rheb-driven mTOR S2481 autophosphorylation and S6K1 phosphorylation require S1261 phosphorylation. These data provide the first evidence that site-specific mTOR phosphorylation regulates mTORC1 function and suggest a model whereby insulin-stimulated mTOR S1261 phosphorylation promotes mTORC1 autokinase activity, substrate phosphorylation, and cell growth.
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Affiliation(s)
- Hugo A Acosta-Jaquez
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200, USA
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Lefterova MI, Mullican SE, Tomaru T, Qatanani M, Schupp M, Lazar MA. Endoplasmic reticulum stress regulates adipocyte resistin expression. Diabetes 2009; 58:1879-86. [PMID: 19491212 PMCID: PMC2712799 DOI: 10.2337/db08-1706] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 05/08/2009] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Resistin is a secreted polypeptide that impairs glucose metabolism and, in rodents, is derived exclusively from adipocytes. In murine obesity, resistin circulates at elevated levels but its gene expression in adipose tissue is paradoxically reduced. The mechanism behind the downregulation of resistin mRNA is poorly understood. We investigated whether endoplasmic reticulum (ER) stress, which is characteristic of obese adipose tissue, regulates resistin expression in cultured mouse adipocytes. RESEARCH DESIGN AND METHODS The effects of endoplasmic stress inducers on resistin mRNA and secreted protein levels were examined in differentiated 3T3-L1 adipocytes, focusing on the expression and genomic binding of transcriptional regulators of resistin. The association between downregulated resistin mRNA and induction of ER stress was also investigated in the adipose tissue of mice fed a high-fat diet. RESULTS ER stress reduced resistin mRNA in 3T3-L1 adipocytes in a time- and dose-dependent manner. The effects of ER stress were transcriptional because of downregulation of CAAT/enhancer binding protein-alpha and peroxisome proliferator-activated receptor-gamma transcriptional activators and upregulation of the transcriptional repressor CAAT/enhancer binding protein homologous protein-10 (CHOP10). Resistin protein was also substantially downregulated, showing a close correspondence with mRNA levels in 3T3-L1 adipocytes as well as in the fat pads of obese mice. CONCLUSIONS ER stress is a potent regulator of resistin, suggesting that ER stress may underlie the local downregulation of resistin mRNA and protein in fat in murine obesity. The paradoxical increase in plasma may be because of various systemic abnormalities associated with obesity and insulin resistance.
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Affiliation(s)
- Martina I. Lefterova
- From the Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Shannon E. Mullican
- From the Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Takuya Tomaru
- From the Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Mohammed Qatanani
- From the Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Michael Schupp
- From the Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Mitchell A. Lazar
- From the Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Department of Genetics, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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Iwai M, Tomono Y, Inaba S, Kanno H, Senba I, Mogi M, Horiuchi M. AT2 receptor deficiency attenuates adipocyte differentiation and decreases adipocyte number in atherosclerotic mice. Am J Hypertens 2009; 22:784-91. [PMID: 19444223 DOI: 10.1038/ajh.2009.85] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Previous reports indicated that blockade of AT(1) receptor stimulation attenuated adipocyte dysfunction. However, the effects of AT(2) receptor stimulation on adipose tissue were not yet clear. In the present study, we examined the adipose tissue dysfunction in atherosclerotic apolipoprotein E knockout (ApoEKO) mice with AT(2) receptor deficiency. METHODS Male ApoEKO and AT(2) receptor/ApoE knockout (AT(2)/ApoEKO) mice at 6 weeks of age were treated with a normal diet or a high-cholesterol diet (HCD: 1.25% cholesterol). Markers for adipocyte differentiation and inflammation in adipose tissue were assayed with real-time reverse-transcription-PCR and western blot. RESULTS Compared with ApoEKO mice, AT(2)/ApoEKO mice with a normal diet showed only a decrease in expression of adiponectin and CCAAT/enhancer binding protein delta (C/EBPdelta) in epididymal adipose tissue without changes in body weight, adipose tissue weight, and adipocyte number even at 6 months of age. After HCD for 4 weeks, the weight of both epididymal and retroperitoneal adipose tissue in AT(2)/ApoEKO mice was greater than that in ApoEKO mice without a change in body weight. Plasma concentrations of cholesterol and fatty acids were higher in AT(2)/ApoEKO mice than in ApoEKO mice. In adipose tissue of AT(2)/ApoEKO mice, the adipocyte number was decreased and the expression of peroxisome proliferator-activated receptor gamma (PPARgamma), C/EBPalpha, and aP2 was lower than that in ApoEKO mice, in association with an increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. CONCLUSIONS These results suggest that AT(2) receptor stimulation in adipose tissue is involved in the improvement of adipocyte differentiation and adipose tissue dysfunction in atherosclerotic model.
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CCAAT/enhancer-binding protein beta: its role in breast cancer and associations with receptor tyrosine kinases. Expert Rev Mol Med 2009; 11:e12. [PMID: 19351437 DOI: 10.1017/s1462399409001033] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The CCAAT/enhancer-binding proteins (C/EBPs) are a family of leucine-zipper transcription factors that regulate gene expression to control cellular proliferation, differentiation, inflammation and metabolism. Encoded by an intronless gene, C/EBPbeta is expressed as several distinct protein isoforms (LAP1, LAP2, LIP) whose expression is regulated by the differential use of several in-frame translation start sites. LAP1 and LAP2 are transcriptional activators and are associated with differentiation, whereas LIP is frequently elevated in proliferative tissue and acts as a dominant-negative inhibitor of transcription. However, emerging evidence suggests that LIP can serve as a transcriptional activator in some cellular contexts, and that LAP1 and LAP2 might also have unique actions. The LIP:LAP ratio is crucial for the maintenance of normal growth and development, and increases in this ratio lead to aggressive forms of breast cancer. This review discusses the regulation of C/EBPbeta activity by post-translational modification, the individual actions of LAP1, LAP2 and LIP, and the functions and downstream targets that are unique to each isoform. The role of the C/EBPbeta isoforms in breast cancer is discussed and emphasis is placed on their interactions with receptor tyrosine kinases.
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Lefterova MI, Lazar MA. New developments in adipogenesis. Trends Endocrinol Metab 2009; 20:107-14. [PMID: 19269847 DOI: 10.1016/j.tem.2008.11.005] [Citation(s) in RCA: 622] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 11/11/2008] [Accepted: 11/14/2008] [Indexed: 01/05/2023]
Abstract
The obesity epidemic has focused attention on adipose tissue and the development of fat cells (i.e. adipocytes), which is known as adipogenesis. Peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding proteins have emerged as master regulators of adipogenesis, and recent genome-wide studies have indicated widespread overlap in their transcriptional targets. In addition, new evidence has implicated many other factors as positive and negative regulators of adipocyte development. This review highlights recent advances in the field of adipogenesis, including newly identified determinants of brown adipocytes, the function of which is to burn rather than store energy. Improved understanding of brown and white adipocyte origins and the integrative biology of adipogenesis might lead to more effective strategies for the treatment of obesity and metabolic disease.
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Affiliation(s)
- Martina I Lefterova
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Lefterova MI, Zhang Y, Steger DJ, Schupp M, Schug J, Cristancho A, Feng D, Zhuo D, Stoeckert CJ, Liu XS, Lazar MA. PPARgamma and C/EBP factors orchestrate adipocyte biology via adjacent binding on a genome-wide scale. Genes Dev 2009; 22:2941-52. [PMID: 18981473 DOI: 10.1101/gad.1709008] [Citation(s) in RCA: 618] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Peroxisome proliferator-activated receptor gamma(PPARgamma), a nuclear receptor and the target of anti-diabetic thiazolinedione drugs, is known as the master regulator of adipocyte biology. Although it regulates hundreds of adipocyte genes, PPARgamma binding to endogenous genes has rarely been demonstrated. Here, utilizing chromatin immunoprecipitation (ChIP) coupled with whole genome tiling arrays, we identified 5299 genomic regions of PPARgamma binding in mouse 3T3-L1 adipocytes. The consensus PPARgamma/RXRalpha "DR-1"-binding motif was found at most of the sites, and ChIP for RXRalpha showed colocalization at nearly all locations tested. Bioinformatics analysis also revealed CCAAT/enhancer-binding protein (C/EBP)-binding motifs in the vicinity of most PPARgamma-binding sites, and genome-wide analysis of C/EBPalpha binding demonstrated that it localized to 3350 of the locations bound by PPARgamma. Importantly, most genes induced in adipogenesis were bound by both PPARgamma and C/EBPalpha, while very few were PPARgamma-specific. C/EBPbeta also plays a role at many of these genes, such that both C/EBPalpha and beta are required along with PPARgamma for robust adipocyte-specific gene expression. Thus, PPARgamma and C/EBP factors cooperatively orchestrate adipocyte biology by adjacent binding on an unanticipated scale.
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Affiliation(s)
- Martina I Lefterova
- Institute for Diabetes, Obesity, and Metabolism, and Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Du K, Ding J. Insulin regulates TRB3 and other stress-responsive gene expression through induction of C/EBPbeta. Mol Endocrinol 2009; 23:475-85. [PMID: 19164449 DOI: 10.1210/me.2008-0284] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Pseudokinase TRB3 is an inducible gene whose expression is regulated by stress response and insulin and associated with insulin resistance and metabolic syndrome. In this report, we have investigated the mechanism under which insulin regulates TRB3 gene expression and demonstrated that insulin induces TRB3 expression via C/EBPbeta. We found that in Fao hepatoma and 3T3-L1 adipocytes, C/EBPbeta expression induced by insulin preceded that of TRB3 and that mutation of the C/EBPbeta binding site in TRB3 promoter abolished the responsiveness of the TRB3 gene to insulin. We further showed that ectopic expression of C/EBPbeta augmented, whereas knockdown of C/EBPbeta reduced, TRB3 expression induced by insulin. In addition, we presented data to show that insulin, through a similar mechanism under which insulin induces TRB3 expression, promotes the expression of genes such as ANAS, ATF3, BIP, and CHOP, which are typical stress-responsive genes. We also examined the impact of C/EBPbeta expression on Akt activation and found that inaction of C/EBPbeta not only augmented Akt activation but also obliterated the suppression of Akt activation due to prolonged insulin stimulation. We suggest, through induction of C/EBPbeta in hepatic cells and adipocytes, that insulin induces the expression of stress-responsive genes, which may represent a novel insulin action.
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Affiliation(s)
- Keyong Du
- Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts 02111, USA.
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Tomaru T, Steger DJ, Lefterova MI, Schupp M, Lazar MA. Adipocyte-specific expression of murine resistin is mediated by synergism between peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding proteins. J Biol Chem 2009; 284:6116-25. [PMID: 19126543 DOI: 10.1074/jbc.m808407200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Resistin antagonizes insulin action in mouse, making it a potential therapeutic target for treating metabolic diseases such as diabetes. To better understand how mouse resistin gene (Retn) expression is restricted to fat tissue, we identified an adipocyte-specific enhancer located approximately 8.8-kb upstream of the transcription start site. This region contains a binding site for the master adipogenic regulator peroxisome proliferator-activated receptor gamma (PPARgamma), and binds endogenous PPARgamma together with its partner retinoid-X receptor alpha (RXRalpha). It also contains three binding sites for CCAAT/enhancer-binding protein (C/EBP), and is bound by endogenous C/EBPalpha and C/EBPbeta in adipocytes. Exogenous expression of PPARgamma/RXRalpha and C/EBPalpha in non-adipocyte cells synergistically drives robust expression from the enhancer. Although PPARgamma ligands repress Retn transcription in adipocytes, rosiglitazone paradoxically stimulates the enhancer activity, suggesting that the enhancer is not directly involved in negative regulation. Unlike expression of Retn in mouse, human resistin (RETN) is expressed primarily in macrophages. Interestingly, the region homologous to the mouse Retn enhancer in the human gene contains all three C/EBP elements, but is not conserved for the sequence bound by PPARgamma. Furthermore, it displays little or no binding by PPARgamma in vitro. Taken together, the data suggest that a composite enhancer binding both PPARgamma and C/EBP factors confers adipocyte-specific expression to Retn in mouse, and its absence from the human gene may explain the lack of adipocyte expression in humans.
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Affiliation(s)
- Takuya Tomaru
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6149, USA
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Abstract
Stem cells are a powerful resource for cell-based transplantation therapies in osteodegenerative disorders, but before some kinds of stem cells can be applied clinically, several aspects of their expansion and differentiation need to be better controlled. Wnt molecules and members of the Wnt signaling cascade have been ascribed a role in both these processes in vitro as well as normal development in vivo. However some results are controversial. In this review we will present the hypothesis that both canonical and non-canonical signaling are involved in mesenchymal cell fate regulation, such as adipogenesis, chondrogenesis and osteogenesis, and that in vitro it is a timely switch between the two that specifies the identity of the differentiating cell. We will specifically focus on the in vitro differentiation of adipocytes, chondrocytes and osteoblasts contrasting embryonic and mesenchymal stem cells as well as the role of Wnts in mesenchymal fate specification during embryogenesis.
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Affiliation(s)
- L. A. Davis
- Department of Surgery and Cambridge Institute for Medical Research, Addenbrooke’s Hospital, University of Cambridge, Hills Road, Cambridge, CB2 2XY United Kingdom
| | - N. I. zur Nieden
- Fraunhofer Institute for Cell Therapy and Immunology, Deutscher Platz 5e, 04103 Leipzig, Germany
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Dong J, Ishimori N, Paigen B, Tsutsui H, Fujii S. Role of modulator recognition factor 2 in adipogenesis and leptin expression in 3T3-L1 cells. Biochem Biophys Res Commun 2007; 366:551-5. [PMID: 18070594 DOI: 10.1016/j.bbrc.2007.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Accepted: 12/01/2007] [Indexed: 10/22/2022]
Abstract
The complex network of adipogenic transcription factors regulates adipocyte differentiation, obesity, and insulin resistance. Modulator recognition factor (Mrf) 2 knockout mice exhibit defects in fat accumulation and are protected from diet-induced obesity, suggesting that Mrf2 deficiency affects adipogenesis. Here, we report that the gene expressions of the 2 isoforms of the transcription factors Mrf2, Mrf2alpha, and Mrf2beta, were induced upon adipogenesis in 3T3-L1 cells. Mrf2 mRNA expression was sensitive to stimulation by insulin, dexamethasone, and TNF-alpha in 3T3-L1 preadipocytes and differentiated adipocytes. Down-regulation of Mrf2alpha and Mrf2beta gene expressions induced by small interfering RNAs increased the mRNA expression of leptin. These results indicate that Mrf2 can be a potential regulator of adipocyte differentiation and a potential repressor of leptin.
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Affiliation(s)
- Jie Dong
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Freson K, Stolarz K, Aerts R, Brand E, Brand-Herrmann SM, Kawecka-Jaszcz K, Kuznetsova T, Tikhonoff V, Thijs L, Vermylen J, Staessen JA, Van Geet C. -391 C to G substitution in the regulator of G-protein signalling-2 promoter increases susceptibility to the metabolic syndrome in white European men: consistency between molecular and epidemiological studies. J Hypertens 2007; 25:117-25. [PMID: 17143182 DOI: 10.1097/hjh.0b013e3280109c6c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND The regulator of G-protein signalling-2 (RGS2) is a key factor in adipogenesis. We hypothesized that the metabolic syndrome, of which obesity is an important component, might be related to genetic variation in RGS2. METHODS AND RESULTS We screened the human RGS2 gene. We tested the functionality of a common genetic variant in vitro, ex vivo, and in epidemiological study involving six European populations. The C to G substitution at position -391 in the RGS2 promoter was associated with enhanced RGS2 expression in vitro in transfected 3T3-L1 adipocytes and Chinese hamster cells and ex vivo in adipocytes from male, but not female, volunteers. In 2732 relatives from 512 families and 348 unrelated individuals, randomly recruited from six European populations, the prevalence of GG homozygosity was 54.1%. The metabolic syndrome score, a composite of six continuous traits making up this clinical entity, was 0.27 standardized units higher (P < 0.001) in 795 GG homozygous men compared with 683 men carrying the C allele. Transmission of the -391 G allele to male offspring was associated with a 0.20 unit increase in the score (P=0.039). These epidemiological relations were not significant in 1602 women. CONCLUSIONS The C to G substitution at position -391 in the RGS2 promoter increases RGS2 expression in adipocytes and is associated with the metabolic syndrome in white European men. Further experimental and clinical research should establish whether this common polymorphism might be a target for preventive or therapeutic intervention.
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Affiliation(s)
- Kathleen Freson
- Center for Molecular and Vascular Biology, University Hospital Gasthuisberg, University of Leuven, Belgium
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Xu Y, Zhou YL, Ann DK, MacDougald OA, Shum L, Snead ML. Transcription factor sumoylation and factor YY1 serve to modulate mouse amelogenin gene expression. Eur J Oral Sci 2006; 114 Suppl 1:169-77; discussion 201-2, 381. [PMID: 16674681 DOI: 10.1111/j.1600-0722.2006.00319.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amelogenin proteins are essential in the control of enamel biomineralization and the amelogenin gene therefore is spatiotemporally regulated to ensure proper amelogenin protein expression. In this study, we examined the role of sumoylation to alter CCAAT/enhancer-binding protein alpha (C/EBPalpha) activity, and performed a search using a protein/DNA array system for other proteins that act co-operatively with C/EBPalpha to alter amelogenin expression. We observed that C/EBPalpha was modified by sumoylation, and that this modification played an indirect inhibitory role on the regulation of C/EBPalpha activity which appeared to act through other transcription factors. The protein/DNA array allowed us to single out the transcription factor, YY1, which acts in the absence of direct DNA binding to repress both the basal amelogenin promoter activity and C/EBPalpha-mediated transactivation. Taken together, these pathways may account for part of the physiological modulation of the amelogenin gene expression in accordance with tooth developmental and enamel biomineralization requirements.
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Affiliation(s)
- Yucheng Xu
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
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Liu HK, Perrier S, Lipina C, Finlay D, McLauchlan H, Hastie CJ, Hundal HS, Sutherland C. Functional characterisation of the regulation of CAAT enhancer binding protein alpha by GSK-3 phosphorylation of Threonines 222/226. BMC Mol Biol 2006; 7:14. [PMID: 16600022 PMCID: PMC1456981 DOI: 10.1186/1471-2199-7-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Accepted: 04/06/2006] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Glycogen Synthase Kinase-3 (GSK3) activity is repressed following insulin treatment of cells. Pharmacological inhibition of GSK3 mimics the effect of insulin on Phosphoenolpyruvate Carboxykinase (PEPCK), Glucose-6 Phosphatase (G6Pase) and IGF binding protein-1 (IGFBP1) gene expression. CAAT/enhancer binding protein alpha (C/EBPalpha) regulates these gene promoters in liver and is phosphorylated on two residues (T222/T226) by GSK3, although the functional outcome of the phosphorylation has not been established. We aimed to establish whether CEBPalpha is a link between GSK3 and these gene promoters. RESULTS C/EBPalpha represses the IGFBP1 thymine-rich insulin response element (TIRE), but mutation of T222 or T226 of C/EBPalpha to non-phosphorylatable alanines has no effect on C/EBPalpha activity in liver cells (towards the TIRE or a consensus C/EBP binding sequence). Phosphorylation of T222/T226 is decreased by GSK3 inhibition, suggesting GSK3 does phosphorylate T222/226 in intact cells. However, phosphorylation was not altered by treatment of liver cells with insulin. Meanwhile C/EBPalpha activity in 3T3 L1 preadipocytes was enhanced by mutation of T222/T226 and/or S230 to alanine residues. Finally, we demonstrate that C/EBPalpha is a very poor substrate for GSK3 in vitro and in cells. CONCLUSION The work demonstrates an important role for this domain in the regulation of C/EBPalpha activity in adipocytes but not hepatocytes, however GSK3 phosphorylation of these residues does not mediate regulation of this C/EBP activity. In short, we find no evidence that C/EBPalpha activity is regulated by direct phosphorylation by GSK3.
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Affiliation(s)
- H-K Liu
- Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
- National Research Institute of Chinese Medicine, Taipei, Taiwan, Republic of China
| | - S Perrier
- Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
| | - C Lipina
- Division of Pathology and Neurosciences, Ninewells Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - D Finlay
- Division of Pathology and Neurosciences, Ninewells Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - H McLauchlan
- Division of Signal Transduction and Therapy, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
| | - CJ Hastie
- Division of Signal Transduction and Therapy, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
| | - HS Hundal
- Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
| | - C Sutherland
- Division of Pathology and Neurosciences, Ninewells Medical School, University of Dundee, Dundee, DD1 9SY, UK
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Zang Y, Wang T, Xie W, Wang-Fischer YL, Getty L, Han J, Corkey BE, Guo W. Regulation of acetyl CoA carboxylase and carnitine palmitoyl transferase-1 in rat adipocytes. ACTA ACUST UNITED AC 2005; 13:1530-9. [PMID: 16222055 DOI: 10.1038/oby.2005.188] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Acetyl CoA carboxylase (ACC) is a key enzyme in energy balance. It controls the synthesis of malonyl-CoA, an allosteric inhibitor of carnitine palmitoyltransferase-1 (CPT-I). CPT-I is the gatekeeper of free fatty acid (FFA) oxidation. To test the hypothesis that both enzymes play critical roles in regulation of FFA partitioning in adipocytes, we compared enzyme mRNA expression and specific activity from fed, fasted, and diabetic rats. RESEARCH METHODS AND PROCEDURES Direct effects of nutritional state, insulin, and FFAs on CPT-I and ACC mRNA expression were assessed in adipocytes, liver, and cultured adipose tissue explants. We also determined FFA partitioning in adipocytes from donors exposed to different nutritional conditions. RESULTS CPT-I mRNA and activity decreased in adipocytes but increased in liver in response to fasting. ACC mRNA and activity decreased in both adipocytes and liver during fasting. These changes were not caused directly by fasting-associated changes in plasma insulin and FFA concentrations because insulin suppressed CPT-I mRNA and did not affect ACC mRNA in vitro, whereas exogenous oleate had no effect on either. Despite the decrease in adipocyte CPT-I mRNA and specific activity, CO(2) production from endogenous FFAs increased, suggesting increased FFA transport through CPT-I for beta-oxidation. DISCUSSION Stimulation of FFA transport through CPT-I occurs in both tissues, but CPT-I mRNA and specific activity correlate with FFA transport in liver and not in adipocytes. We conclude that the mechanism responsible for increasing FFA oxidation in adipose tissue during fasting involves mainly allosteric regulation, whereas altered gene expression may play a central role in the liver.
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Affiliation(s)
- Yan Zang
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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Wei E, Lehner R, Vance D. C/EBPalpha activates the transcription of triacylglycerol hydrolase in 3T3-L1 adipocytes. Biochem J 2005; 388:959-66. [PMID: 15752068 PMCID: PMC1183477 DOI: 10.1042/bj20041442] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
TGH (triacylglycerol hydrolase) catalyses the lipolysis of intracellular stored triacylglycerol. To explore the mechanisms that regulate TGH expression in adipose tissue, we studied the expression of TGH during the differentiation of 3T3-L1 adipocytes. TGH mRNA and protein levels increased dramatically in 3T3-L1 adipocytes compared with pre-adipocytes. Electrophoretic mobility shift assays demonstrated enhanced binding of nuclear proteins of adipocytes to the distal murine TGH promoter region (-542/-371 bp), yielding one adipocyte-specific migrating complex. Competitive and supershift assays demonstrated that the distal TGH promoter fragment bound C/EBPalpha (CCAAT/enhancer-binding protein alpha). Transient transfections of different mutant TGH promoter-luciferase constructs into 3T3-L1 adipocytes and competitive electromobility shift assays showed that the C/EBP-binding elements at positions -470/-459 bp and -404/-390 bp are important for transcriptional activation. Co-transfection with C/EBPalpha cDNA and TGH promoter constructs in 3T3-L1 pre-adipocytes demonstrated that C/EBPalpha increased TGH promoter activity. Ectopic expression of C/EBPalpha in NIH 3T3 cells activated TGH mRNA expression without causing differentiation into adipocytes. These experiments directly link increased TGH expression in adipocytes to transcriptional regulation by C/EBPalpha. This is the first evidence that C/EBPalpha participates directly in the regulation of an enzyme associated with lipolysis.
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Affiliation(s)
- Enhui Wei
- *Department of Biochemistry and CIHR Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
- †Department of Pediatrics and CIHR Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Richard Lehner
- †Department of Pediatrics and CIHR Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
- ‡Department of Cell Biology and CIHR Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Dennis E. Vance
- *Department of Biochemistry and CIHR Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
- To whom correspondence should be addressed (email )
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Abstract
Cell culture models have been developed to study commitment and subsequent differentiation of preadipocytes into adipocytes. Bone morphogenetic protein 4 commits mesenchymal stem cells to the adipose lineage. Other factors, including Wnt signaling, cell density, and cell shape, play a role in lineage commitment. Following commitment to the adipose lineage, growth-arrested preadipocytes can differentiate to adipocytes by treatment with insulin-like growth factor 1, glucocorticoid and an agent that increases cAMP level. This process is characterized by a rapid and transient increase in CCAAT/enhancer binding protein (C/EBP) beta and synchronous re-entry into the cell cycle. Acquisition of DNA-binding by C/EBPbeta occurs after the transcription factor becomes phosphorylated. The cells enter a growth-arrested state and begin terminal differentiation. C/EBPalpha, peroxisome proliferator-activated receptor gamma, and adipocyte determination, and differentiation-dependent factor 1 coordinate the expression of genes that create and maintain the adipocyte phenotype.
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Affiliation(s)
- Tamara C Otto
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Rudic RD, McNamara P, Reilly D, Grosser T, Curtis AM, Price TS, Panda S, Hogenesch JB, FitzGerald GA. Bioinformatic analysis of circadian gene oscillation in mouse aorta. Circulation 2005; 112:2716-24. [PMID: 16230482 DOI: 10.1161/circulationaha.105.568626] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Circadian rhythmicity of many aspects of cardiovascular function-blood pressure, coagulation and contractile function-is well established, as is diurnal variation in important clinical events, such as myocardial infarction and stroke. Here, we undertake studies to globally assess circadian gene expression in murine aorta. METHODS AND RESULTS Aortae from mice were harvested at 4-hour intervals for 2 circadian cycles (48 hours). Gene expression was assessed by expression profiling and subjected to a gene ontology bioinformatics analysis. Three hundred thirty transcripts exhibited a circadian pattern of oscillation in mouse aorta, including those intrinsic to the function of the molecular clock. In addition, many genes relevant to protein folding, protein degradation, glucose and lipid metabolism, adipocyte maturation, vascular integrity, and the response to injury are also included in this subset of roughly 7000 genes screened for circadian oscillation. CONCLUSIONS Detection of functional cassettes of vascular genes that exhibit circadian regulation in the mouse will facilitate elucidation of the mechanisms by which the molecular clock may interact with environmental variables to modulate cardiovascular function and the response to therapeutic interventions.
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Affiliation(s)
- R Daniel Rudic
- The Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
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