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Zhang X, Ding X, Wang C, Le Q, Wu D, Song A, Huang G, Luo L, Luo Y, Yang X, Goins AE, Desai SP, Qiu C, Silva FD, Feldman LE, Zhou J, Spafford MF, Boyd NH, Prossnitz ER, Yang XO, Wang QA, Liu M. Depletion of JunB increases adipocyte thermogenic capacity and ameliorates diet-induced insulin resistance. Nat Metab 2024; 6:78-93. [PMID: 38191667 PMCID: PMC10954369 DOI: 10.1038/s42255-023-00945-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 11/10/2023] [Indexed: 01/10/2024]
Abstract
The coexistence of brown adipocytes with low and high thermogenic activity is a fundamental feature of brown adipose tissue heterogeneity and plasticity. However, the mechanisms that govern thermogenic adipocyte heterogeneity and its significance in obesity and metabolic disease remain poorly understood. Here we show that in male mice, a population of transcription factor jun-B (JunB)-enriched (JunB+) adipocytes within the brown adipose tissue exhibits lower thermogenic capacity compared to high-thermogenic adipocytes. The JunB+ adipocyte population expands in obesity. Depletion of JunB in adipocytes increases the fraction of adipocytes exhibiting high thermogenic capacity, leading to enhanced basal and cold-induced energy expenditure and protection against diet-induced obesity and insulin resistance. Mechanistically, JunB antagonizes the stimulatory effects of PPARγ coactivator-1α on high-thermogenic adipocyte formation by directly binding to the promoter of oestrogen-related receptor alpha, a PPARγ coactivator-1α downstream effector. Taken together, our study uncovers that JunB shapes thermogenic adipocyte heterogeneity, serving a critical role in maintaining systemic metabolic health.
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Affiliation(s)
- Xing Zhang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Xiaofeng Ding
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Chunqing Wang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Que Le
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Dandan Wu
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Anying Song
- Department of Molecular & Cellular Endocrinology, City of Hope Comprehensive Cancer Center, Duarte, CA, USA
| | - Guixiang Huang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, People's Republic of China
| | - Liping Luo
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Yan Luo
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Xin Yang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Aleyah E Goins
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Sharina P Desai
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Chengrui Qiu
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Floyd D Silva
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Lily Elizabeth Feldman
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Jianlin Zhou
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, People's Republic of China
| | - Michael F Spafford
- Department of Surgery, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Nathan H Boyd
- Department of Surgery, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Eric R Prossnitz
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
- Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
- UNM Comprehensive Cancer Center (UNMCCC), University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Xuexian O Yang
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Qiong A Wang
- Department of Molecular & Cellular Endocrinology, City of Hope Comprehensive Cancer Center, Duarte, CA, USA
| | - Meilian Liu
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
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2
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Meriin AB, Zaarur N, Roy D, Kandror KV. Egr1 plays a major role in the transcriptional response of white adipocytes to insulin and environmental cues. Front Cell Dev Biol 2022; 10:1003030. [PMID: 36246998 PMCID: PMC9554007 DOI: 10.3389/fcell.2022.1003030] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 09/08/2022] [Indexed: 11/18/2022] Open
Abstract
It is believed that insulin regulates metabolic functions of white adipose tissue primarily at the post-translational level via the PI3K-Akt-mediated pathway. Still, changes in transcription also play an important role in the response of white adipocytes to insulin and environmental signals. One transcription factor that is dramatically and rapidly induced in adipocytes by insulin and nutrients is called Early Growth Response 1, or Egr1. Among other functions, it directly binds to promoters of leptin and ATGL stimulating the former and inhibiting the latter. Furthermore, expression of Egr1 in adipocytes demonstrates cell autonomous circadian pattern suggesting that Egr1 not only mediates the effect of insulin and nutrients on lipolysis and leptin production but also, coordinates insulin action with endogenous circadian rhythms of adipose tissue.
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Affiliation(s)
- A. B. Meriin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States
| | - N. Zaarur
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States
| | - D. Roy
- Department of Neuroscience, The Ohio State University, Columbus, OH, United States
| | - K. V. Kandror
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States
- *Correspondence: K. V. Kandror,
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3
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Chinta PK, Tambe S, Umrani D, Pal AK, Nandave M. Effect of parthenolide, an NLRP3 inflammasome inhibitor, on insulin resistance in high-fat diet-obese mice. Can J Physiol Pharmacol 2022; 100:272-281. [PMID: 35119950 DOI: 10.1139/cjpp-2021-0116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The activation of Nod-like receptor proteins (NLRP3) containing the pyrin domain inflammasome is a hallmark of the pathogenesis of metabolic disorders. Inhibition of the NLRP3 inflammasome by phytoconstituents has been attempted as a strategy to mitigate these disorders. Therefore, the present study aimed to evaluate the efficacy of an NLRP3 inflammasome inhibitor, parthenolide (PN; 5 mg/kg i.p.) against inflammation and insulin resistance in high-fat diet (HFD) - obese mice. Treatment with PN and pioglitazone (PIO; 30 mg/kg p.o.) attenuated lipopolysaccharide (LPS; 1 ng/ml) - induced elevation of tumor necrosis factor-α and interleukin-1β in mouse peritoneal macrophages in a dose-dependent manner. Sixty days of PN and PIO treatment marginally reduced obesity-induced insulin resistance in HFD-obese mice. PN treatment also decreased blood glucose from 14th to 60th day, supporting the hypothesis of simultaneous attenuation of inflammation and insulin resistance in obese mice. Thus, PN treatment was also evident with significant improvement in glucose tolerance and peripheral insulin resistance validated through the respective tolerance tests. Therefore, the present study suggests that PN, an NLRP3 inflammasome inhibitor, could be a possible therapeutic agent for attenuating obesity-induced insulin resistance.
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Affiliation(s)
| | | | | | - Ajay Kumar Pal
- Department of Pharmacology, Delhi Pharmaceutical Sciences and Research University (DPSRU), New Delhi-110017, INDIA
| | - Mukesh Nandave
- Department of Pharmacology, Delhi Pharmaceutical Sciences and Research University (DPSRU), New Delhi-110017, INDIA
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4
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Tang P, Virtue S, Goie JYG, Png CW, Guo J, Li Y, Jiao H, Chua YL, Campbell M, Moreno-Navarrete JM, Shabbir A, Fernández-Real JM, Gasser S, Kemeny DM, Yang H, Vidal-Puig A, Zhang Y. Regulation of adipogenic differentiation and adipose tissue inflammation by interferon regulatory factor 3. Cell Death Differ 2021; 28:3022-3035. [PMID: 34091599 PMCID: PMC8563729 DOI: 10.1038/s41418-021-00798-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 02/04/2023] Open
Abstract
Dysfunction of adipocytes and adipose tissue is a primary defect in obesity and obesity-associated metabolic diseases. Interferon regulatory factor 3 (IRF3) has been implicated in adipogenesis. However, the role of IRF3 in obesity and obesity-associated disorders remains unclear. Here, we show that IRF3 expression in human adipose tissues is positively associated with insulin sensitivity and negatively associated with type 2 diabetes. In mouse pre-adipocytes, deficiency of IRF3 results in increased expression of PPARγ and PPARγ-mediated adipogenic genes, leading to increased adipogenesis and altered adipocyte functionality. The IRF3 knockout (KO) mice develop obesity, insulin resistance, glucose intolerance, and eventually type 2 diabetes with aging, which is associated with the development of white adipose tissue (WAT) inflammation. Increased macrophage accumulation with M1 phenotype which is due to the loss of IFNβ-mediated IL-10 expression is observed in WAT of the KO mice compared to that in wild-type mice. Bone-marrow reconstitution experiments demonstrate that the nonhematopoietic cells are the primary contributors to the development of obesity and both hematopoietic and nonhematopoietic cells contribute to the development of obesity-related complications in IRF3 KO mice. This study demonstrates that IRF3 regulates the biology of multiple cell types including adipocytes and macrophages to prevent the development of obesity and obesity-related complications and hence, could be a potential target for therapeutic interventions for the prevention and treatment of obesity-associated metabolic disorders.
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Affiliation(s)
- Peng Tang
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Sam Virtue
- Institute of Metabolic Science, Wellcome Trust-MRC MDU Metabolic Disease Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Jian Yi Gerald Goie
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Chin Wen Png
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Jing Guo
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Ying Li
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Huipeng Jiao
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Yen Leong Chua
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Mark Campbell
- Institute of Metabolic Science, Wellcome Trust-MRC MDU Metabolic Disease Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - José Maria Moreno-Navarrete
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigacio Biomedica de Girona (IDIBGI), CIBER Fisiopatologia de la Obesidad y Nutricion (CIBERobn, CB06/03/010), Instituto de Salud Carlos III, and Department of Medical Sciences, Faculty of Medicine, Girona, Spain
| | - Asim Shabbir
- Department of Surgery, National University Hospital, Singapore, Singapore
| | - José-Manuel Fernández-Real
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigacio Biomedica de Girona (IDIBGI), CIBER Fisiopatologia de la Obesidad y Nutricion (CIBERobn, CB06/03/010), Instituto de Salud Carlos III, and Department of Medical Sciences, Faculty of Medicine, Girona, Spain
| | - Stephan Gasser
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - David Michael Kemeny
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Henry Yang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Antonio Vidal-Puig
- Institute of Metabolic Science, Wellcome Trust-MRC MDU Metabolic Disease Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
| | - Yongliang Zhang
- Department of Microbiology & Immunology, and NUSMED Immunology Translational Research Programme,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore.
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5
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Tang F, Guan L, Liu X, Fan P, Zhou M, Wu Y, Liu R, Liu Y, Liu S, Li D, Bai H. A Common R219K Variant of ATP-Binding Cassette Transporter A1 Gene Alters Atherometabolic Traits in Pregnant Women With Gestational Diabetes Mellitus. Front Endocrinol (Lausanne) 2021; 12:782453. [PMID: 34975757 PMCID: PMC8718706 DOI: 10.3389/fendo.2021.782453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/30/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND ATP-binding cassette transporter A1 (ABCA1) has important roles in high-density lipoprotein (HDL) metabolism and reverse cholesterol transport, and is implicated in lipid-related disorders. Genetic variants are involved in the pathogenesis of gestational diabetes mellitus (GDM). The objective of this study was to investigate the association of rs2230806 (R219K), a single nucleotide polymorphism (SNP) in the lipid-related gene, with the risk of GDM and related traits. METHODS The SNP, rs2230806, was genotyped, and clinical and metabolic parameters were determined in 660 GDM patients and 1,097 control subjects. Genetic associations with related traits were also analyzed. RESULTS The genotype distributions were similar in GDM patients and normal controls. However, significant differences in the variables examined in the study subjects were noted across the three genotypes. The genotype at the rs2230806 polymorphism was significantly associated with HDL-cholesterol (HDL-C) levels and atherogenic index (AI) values in GDM patients and total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels in control subjects. Subgroup analysis showed that the polymorphism was associated with diastolic blood pressure, in addition to HDL-C levels and AI, in overweight/obese GDM patients, while it was associated with TC levels, AI, pre-pregnancy body mass index (BMI), and BMI at delivery in non-obese GDM patients. In addition, this polymorphism was associated with TC, LDL-C, and apoB levels in overweight/obese control subjects. CONCLUSIONS The rs2230806 polymorphism in the ABCA1 gene was associated with variations in atherometabolic traits in GDM patients, with characteristics of BMI dependency, but not with GDM. Our findings highlight a link between related phenotypes in women with GDM and genetic factors.
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Affiliation(s)
- Fangmei Tang
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
- West China School of Nursing, Sichuan University, Chengdu, China
| | - Linbo Guan
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Xinghui Liu
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Ping Fan
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Mi Zhou
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yujie Wu
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Rui Liu
- Division of Peptides Related With Human Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Yu Liu
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, China
| | - Sixu Liu
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
- West China School of Nursing, Sichuan University, Chengdu, China
| | - Dehua Li
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
- West China School of Nursing, Sichuan University, Chengdu, China
| | - Huai Bai
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
- *Correspondence: Huai Bai,
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Abstract
Neuroimmunology and immunometabolism are burgeoning topics of study, but the intersection of these two fields is scarcely considered. This interplay is particularly prevalent within adipose tissue, where immune cells and the sympathetic nervous system (SNS) have an important role in metabolic homeostasis and pathology, namely in obesity. In the present Review, we first outline the established reciprocal adipose-SNS relationship comprising the neuroendocrine loop facilitated primarily by adipose tissue-derived leptin and SNS-derived noradrenaline. Next, we review the extensive crosstalk between adipocytes and resident innate immune cells as well as the changes that occur in these secretory and signalling pathways in obesity. Finally, we discuss the effect of SNS adrenergic signalling in immune cells and conclude with exciting new research demonstrating an immutable role for SNS-resident macrophages in modulating SNS-adipose crosstalk. We posit that the latter point constitutes the existence of a new field - neuroimmunometabolism.
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Affiliation(s)
- Chelsea M Larabee
- Department of Physiology, Anatomy & Genetics, Oxford University, Oxford, UK
| | - Oliver C Neely
- Department of Physiology, Anatomy & Genetics, Oxford University, Oxford, UK
| | - Ana I Domingos
- Department of Physiology, Anatomy & Genetics, Oxford University, Oxford, UK.
- The Howard Hughes Medical Institute (HHMI), New York, NY, USA.
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7
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Foss-Freitas MC, Ferraz RC, Monteiro LZ, Gomes PM, Iwakura R, de Freitas LCC, Foss MC. Endoplasmic reticulum stress activation in adipose tissue induces metabolic syndrome in individuals with familial partial lipodystrophy of the Dunnigan type. Diabetol Metab Syndr 2018; 10:6. [PMID: 29449893 PMCID: PMC5807843 DOI: 10.1186/s13098-017-0301-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 12/16/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Familial partial lipodystrophy of the Dunnigan type is one of the most common inherited lipodystrophies variables. These individuals have important metabolic disorders that cause predisposition to various diseases. In this study we aimed to demonstrate the relation between the metabolic abnormalities, inflammatory profile and the expression of genes involved in the activation of the endoplasmic reticulum stress (ERS) in subjects with FPLD. METHODS We evaluated 14 female FPLD patients and compared with 13 female healthy individuals. The subjects were paired with their respective BMI and age and categorized into two groups: Familial partial lipodystrophy of the Dunnigan type (FPLD) and control. Patients were fasted for 12 h before blood collection for measurement of HbA1c, glucose, insulin, lipids and inflammatory markers. Subcutâneous adipose tissue was collected by puncture aspiration of submental region during ambulatorial surgical aesthetic procedure. RESULTS We demonstrate that patients with FPLD show increased HbA1c (p < 0.01), fasting glucose (p < 0.002) and triglycerides (p < 0.005) while HDL/cholesterol (p < 0.001) was lower when compared to healthy individuals. We found that 64.2% FPLD patients had metabolic syndrome according to International Diabetes Federation definition. We also observe increased AUC of glucose (p < 0.001) and insulin during oGTT, featuring a frame of hyperglycemia and hyperinsulinemia, suggesting insulin resistance. Also we found hyperactivation of several genes responsible for ERS such as ATF-4 (p < 0.01), ATF-6 (p < 0.01), EIF2α3K (p < 0.005), CCT4 (p < 0.001), CHOP (p < 0.01), CALR (p < 0.001) and CANX (p < 0.005), that corroborate the idea that diabetes mellitus and metabolic syndrome are associated with direct damage to the endoplasmic reticulum homeostasis. Ultimately, we note that individuals with lipodystrophy have an increase in serum interleukins, keys of the inflammatory process, as IL-1β, TNF-α and IL-6 (p < 0.05 all), compared with healthy individuals, which can be the trigger to insulin resistance in this population. CONCLUSION Individuals with FPLD besides having typical dysfunctions of metabolic syndrome, show a hyperactivation of ERS associated with increased systemic inflammatory profile, which together may explain the complex clinical aspect of this diseases.Trial registration HCRP no 6711/2012.
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Affiliation(s)
- Maria C. Foss-Freitas
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, São Paulo Brazil
| | - Rafael C. Ferraz
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, São Paulo Brazil
| | | | - Patricia M. Gomes
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, São Paulo Brazil
| | - Ricardo Iwakura
- Department of Opthalmology, Otolaryngology, Head and Neck Surgery, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, São Paulo Brazil
| | - Luiz Carlos C. de Freitas
- Department of Opthalmology, Otolaryngology, Head and Neck Surgery, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, São Paulo Brazil
| | - Milton C. Foss
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, São Paulo Brazil
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8
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Plasminogen Activator Inhibitor-1 is Regulated Through Dietary Fat Intake and Heritability: Studies in Twins. Twin Res Hum Genet 2017. [DOI: 10.1017/thg.2017.36] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In different pathophysiological conditions plasminogen activator inhibitor-1 (PAI-1) plasma concentrations are elevated. As dietary patterns are considered to influence PAI-1 concentration, we aimed to determine active PAI-1 plasma concentrations and mRNA expression in adipose tissue before and after consumption of a high-fat diet (HFD) and the impact of additive genetic effects herein in humans. For 6 weeks, 46 healthy, non-obese pairs of twins (aged 18–70) received a normal nutritionally balanced diet (ND) followed by an isocaloric HFD for 6 weeks. Active PAI-1 plasma levels and PAI-1 mRNA expression in subcutaneous adipose tissue were assessed after the ND and after 1 and 6 weeks of HFD. Active PAI-1 plasma concentrations and PAI-1 mRNA expression in adipose tissue were significantly increased after both 1 and 6 weeks of HFD when compared to concentrations determined after ND (p< .05), with increases of active PAI-1 being independent of gender, age, or changes of BMI and intrahepatic fat content, respectively. However, analysis of covariance suggests that serum insulin concentration significantly affected the increase of active PAI-1 plasma concentrations. Furthermore, the increase of active PAI-1 plasma concentrations after 6 weeks of HFD was highly heritable (47%). In contrast, changes in PAI-1 mRNA expression in fatty tissue in response to HFD showed no heritability and were independent of all tested covariates. In summary, our data suggest that even an isocaloric exchange of macronutrients — for example, a switch to a fat-rich diet — affects PAI-1 concentrations in humans and that this is highly heritable.
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Abood S, Eichelbaum S, Mustafi S, Veisaga ML, López LA, Barbieri M. Biomedical Properties and Origins of Sesquiterpene Lactones, with a Focus on Dehydroleucodine. Nat Prod Commun 2017. [DOI: 10.1177/1934578x1701200638] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Dehydroleucodine, a sesquiterpene lactone, belongs to the terpenoid class of secondary metabolites. Dehydroleucodine and other Artemisia-derived phytochemicals evolved numerous biodefenses that were first co-opted for human pharmacological use by traditional cultures in the Middle East, Asia, Europe and the Americas. Later, these phytochemicals were modified through the use of medicinal chemical techniques to increase their potency. All sesquiterpene lactones contain an α-methylene-γ-lactone group, which confers thiol reactivity, which is responsible, in part, for their therapeutic effects. A wide range of therapeutic uses of sequiterpene lactones has been found, including anti-adipogenic, cytoprotective, anti-microbial, anti-viral, anti-fungal, anti-malarial and, anti-migraine effects. Dehydroleucodine significantly inhibits differentiation of murine preadipocytes and also significantly decreases the accumulation of lipid content by a dramatic down regulation of adipogenic-specific transcriptional factors PPARγ and C-EBPα. Dehydroleucodine also inhibits secretion of matrix metalloprotease-2 (MMP-2), which is a known protease involved in migration and invasion of B16 cells. In addition to these anti-adipogenic and anti-cancer effects, dehydroleucodine effectively neutralizes several bacterial species, including Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Helicobacter pylori, methicillin resistant Staphylococcus aueus (MRSA) and S. epidermis (MRSE). The compound also inhibits the growth and secretion of several toxins of Pseudomonas aeruginosa, possesses gastro-protective qualities and possesses anti-parasitic properties against Trypanosoma cruzi, responsible for Chagas disease. Other sesquiterpene lactones, such as parthenolide, costunolide, and helanin, also possess significant therapeutic utility.
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Affiliation(s)
- Steven Abood
- Department of Biological Sciences; Florida International University, Miami, FL 33199, USA
| | - Steven Eichelbaum
- Department of Biological Sciences; Florida International University, Miami, FL 33199, USA
| | - Sushmita Mustafi
- Department of Biological Sciences; Florida International University, Miami, FL 33199, USA
| | - Maria-Luisa Veisaga
- Biomolecular Sciences Institute; Florida International University, Miami, FL 33199, USA
| | - Luis A. López
- Laboratory of Cytoskeleton and Cell Cycle, Institute of Histology and Embryology, Faculty of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - Manuel Barbieri
- Department of Biological Sciences; Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute; Florida International University, Miami, FL 33199, USA
- Fairchild Tropical Botanic Garden, 10901 Old Cutler Road, Coral Gables, FL 33156, USA
- International Center of Tropical Botany, Florida International University, Miami, FL 33199, USA
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10
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Abstract
The mechanisms or causes of pancreatic β-cell death as well as impaired insulin secretion, which are the principal events of diabetic etiopathology, are largely unknown. Diabetic complications are known to be associated with abnormal plasma lipid profile, mainly elevated level of cholesterol and free fatty acids. However, in recent years, elevated plasma cholesterol has been implicated as a primary modulator of pancreatic β-cell functions as well as death. High-cholesterol diet in animal models or excess cholesterol in pancreatic β-cell causes transporter desensitization and results in morphometric changes in insulin granules. Moreover, cholesterol is also held responsible to cause oxidative stress, mitochondrial dysfunction, and activation of proapoptotic markers leading to β-cell death. The present review focuses on the pathways and molecularevents that occur in the β-cell under the influence of excess cholesterol that hampers the basal physiology of the cell leading to the progression of diabetes.
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Interleukin-17A Gene Expression in Morbidly Obese Women. Int J Mol Sci 2015; 16:17469-81. [PMID: 26263971 PMCID: PMC4581203 DOI: 10.3390/ijms160817469] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/23/2015] [Accepted: 07/27/2015] [Indexed: 12/22/2022] Open
Abstract
Data from recent studies conducted in rodent models and humans suggest that interleukin-17A (IL-17A) plays a role in the induction of inflammation in adipose tissue during obesity. The aim of this study was to assess the gene expression of IL-17A in adipose tissue of morbidly obese patients. We used RT-PCR to evaluate the expression of IL-17A and several adipo/cytokines in the visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) of 10 normal-weight control women (BMI < 25 kg/m2) and 30 morbidly obese women (MO, BMI > 40 kg/m2). We measured serum levels of IL-17A and adipo/cytokines in MO and normal weight women. IL-17A expression was significantly higher in VAT than in SAT in MO patients (p = 0.0127). It was very low in normal-weight controls in both VAT and SAT tissues. We found positive correlations between IL-17A and IL-6, lipocalin-2 and resistin in VAT of MO patients. The circulating level of IL-17A was higher in the normal-weight group than the MO patients (p = 0.032), and it was significantly related to adiponectin and TNFRII levels. In conclusion, IL-17A expression in VAT is increased in morbidly obese women, which suggests a link between obesity and innate immunity in low-grade chronic inflammation in morbidly obese women.
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Singh M, Shin YK, Yang X, Zehr B, Chakrabarti P, Kandror KV. 4E-BPs Control Fat Storage by Regulating the Expression of Egr1 and ATGL. J Biol Chem 2015; 290:17331-8. [PMID: 25814662 DOI: 10.1074/jbc.m114.631895] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Indexed: 01/04/2023] Open
Abstract
Early growth response transcription factor Egr1 controls multiple aspects of cell physiology and metabolism. In particular, Egr1 suppresses lipolysis and promotes fat accumulation in adipocytes by inhibiting the expression of adipose triglyceride lipase. According to current dogma, regulation of the Egr1 expression takes place primarily at the level of transcription. Correspondingly, treatment of cultured adipocytes with insulin stimulates expression of Egr1 mRNA and protein. Unexpectedly, the MEK inhibitor PD98059 completely blocks insulin-stimulated increase in the Egr1 mRNA but has only a moderate effect on the Egr1 protein. At the same time, mTORC1 inhibitors rapamycin and PP242 suppress expression of the Egr1 protein and have an opposite effect on the Egr1 mRNA. Mouse embryonic fibroblasts with genetic ablations of TSC2 or 4E-BP1/2 express less Egr1 mRNA but more Egr1 protein than wild type controls. (35)S-labeling has confirmed that translation of the Egr1 mRNA is much more effective in 4E-BP1/2-null cells than in control. A selective agonist of the CB1 receptors, ACEA, up-regulates Egr1 mRNA, but does not activate mTORC1 and does not increase Egr1 protein in adipocytes. These data suggest that although insulin activates both the Erk and the mTORC1 signaling pathways in adipocytes, regulation of the Egr1 expression takes place predominantly via the mTORC1/4E-BP-mediated axis. In confirmation of this model, we show that 4E-BP1/2-null MEFs express less ATGL and accumulate more fat than control cells, while knock down of Egr1 in 4E-BP1/2-null MEFs increases ATGL expression and decreases fat storage.
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Affiliation(s)
- Maneet Singh
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Yu-Kyong Shin
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Xiaoqing Yang
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Brad Zehr
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Partha Chakrabarti
- From the Boston University School of Medicine, Boston, Massachusetts 02118
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Jeong K, Kwon H, Lee J, Jang D, Pak Y. Insulin-response epigenetic activation of Egr-1 and JunB genes at the nuclear periphery by A-type lamin-associated pY19-Caveolin-2 in the inner nuclear membrane. Nucleic Acids Res 2015; 43:3114-27. [PMID: 25753664 PMCID: PMC4381080 DOI: 10.1093/nar/gkv181] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 02/20/2015] [Indexed: 11/15/2022] Open
Abstract
Insulin controls transcription to sustain its physiologic effects for the organism to adapt to environmental changes added to genetic predisposition. Nevertheless, insulin-induced transcriptional regulation by epigenetic factors and in defined nuclear territory remains elusive. Here we show that inner nuclear membrane (INM)-integrated caveolin-2 (Cav-2) regulates insulin-response epigenetic activation of Egr-1 and JunB genes at the nuclear periphery. INM-targeted pY19-Cav-2 in response to insulin associates specifically with the A-type lamin, disengages the repressed Egr-1 and JunB promoters from lamin A/C through disassembly of H3K9me3, and facilitates assembly of H3K9ac, H3K18ac and H3K27ac by recruitment of GCN5 and p300 and the subsequent enrichment of RNA polymerase II (Pol II) on the promoters at the nuclear periphery. Our findings show that Cav-2 is an epigenetic regulator of histone H3 modifications, and provide novel mechanisms of insulin-response epigenetic activation at the nuclear periphery.
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Affiliation(s)
- Kyuho Jeong
- Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Hayeong Kwon
- Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Jaewoong Lee
- Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Donghwan Jang
- Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Yunbae Pak
- Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
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Maternal pregravid obesity changes gene expression profiles toward greater inflammation and reduced insulin sensitivity in umbilical cord. Pediatr Res 2014; 76:202-10. [PMID: 24819376 PMCID: PMC4135718 DOI: 10.1038/pr.2014.72] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Accepted: 02/06/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Maternal obesity is associated with unfavorable outcomes, which may be reflected in the as yet undiscovered gene expression profiles of the umbilical cord (UC). METHODS UCs from 12 lean (pregravid BMI < 24.9) and 10 overweight/obese (pregravid BMI ≥ 25) women without gestational diabetes were collected for gene expression analysis using Human Primeview microarrays. Metabolic parameters were assayed in mother's plasma and cord blood. RESULTS Although offspring birth weight and adiposity (at 2 wk) did not differ between groups, expression of 232 transcripts was affected in UC from overweight/obese compared with those of lean mothers. Gene-set enrichment analysis revealed an upregulation of genes related to metabolism, stimulus and defense response, and inhibitory to insulin signaling in the overweight/obese group. We confirmed that EGR1, periostin, and FOSB mRNA expression was induced in UCs from overweight/obese mothers, while endothelin receptor B, KLF10, PEG3, and EGLN3 expression was decreased. Messenger RNA expression of EGR1, FOSB, MEST, and SOCS1 were positively correlated (P < 0.05) with mother's first-trimester body fat mass (%). CONCLUSION Our data suggest a positive association between maternal obesity and changes in UC gene expression profiles favoring inflammation and insulin resistance, potentially predisposing infants to develop metabolic dysfunction later on in life.
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15
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Dietary obesity-induced Egr-1 in adipocytes facilitates energy storage via suppression of FOXC2. Sci Rep 2013; 3:1476. [PMID: 23502673 PMCID: PMC3600596 DOI: 10.1038/srep01476] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 02/28/2013] [Indexed: 01/27/2023] Open
Abstract
The molecular mechanism to regulate energy balance is not completely understood. Here we observed that Egr-1 expression in white adipose tissue (WAT) was highly correlated with dietary-induced obesity and insulin resistance both in mice and humans. Egr-1 null mice were protected from diet-induced obesity and obesity-associated pathologies such as fatty liver, insulin resistance, hyperlipidemia and hyperinsulinemia. This phenotype can be largely explained by the increase of energy expenditure in Egr-1 null mice. Characterization of these mice revealed that the expression of FOXC2 and its target genes were significantly elevated in white adipose tissues, leading to WAT energy expenditure instead of energy storage. Altogether, these studies suggest an important role for Egr-1, which, by repressing FOXC2 expression, promotes energy storage in WAT and favored the development of obesity under high energy intake.
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Insulin inhibits lipolysis in adipocytes via the evolutionarily conserved mTORC1-Egr1-ATGL-mediated pathway. Mol Cell Biol 2013; 33:3659-66. [PMID: 23858058 DOI: 10.1128/mcb.01584-12] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
One of the basic functions of insulin in the body is to inhibit lipolysis in adipocytes. Recently, we have found that insulin inhibits lipolysis and promotes triglyceride storage by decreasing transcription of adipose triglyceride lipase via the mTORC1-mediated pathway (P. Chakrabarti et al., Diabetes 59:775-781, 2010), although the mechanism of this effect remained unknown. Here, we used a genetic screen in Saccharomyces cerevisiae in order to identify a transcription factor that mediates the effect of Tor1 on the expression of the ATGL ortholog in yeast. This factor, Msn4p, has homologues in mammalian cells that form a family of early growth response transcription factors. One member of the family, Egr1, is induced by insulin and nutrients and directly inhibits activity of the ATGL promoter in vitro and expression of ATGL in cultured adipocytes. Feeding animals a high-fat diet increases the activity of mTORC1 and the expression of Egr1 while decreasing ATGL levels in epididymal fat. We suggest that the evolutionarily conserved mTORC1-Egr1-ATGL regulatory pathway represents an important component of the antilipolytic effect of insulin in the mammalian organism.
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Cruz-Garcia L, Sánchez-Gurmaches J, Gutiérrez J, Navarro I. Role of LXR in trout adipocytes: target genes, hormonal regulation, adipocyte differentiation and relation to lipolysis. Comp Biochem Physiol A Mol Integr Physiol 2012; 163:120-6. [PMID: 22626869 DOI: 10.1016/j.cbpa.2012.05.193] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/16/2012] [Accepted: 05/16/2012] [Indexed: 11/18/2022]
Abstract
In the present study, we describe an initial approach to investigate the role of LXR in fish adipose tissue. Rainbow trout (Oncorhynchus mykiss) isolated adipocytes were incubated with LXR agonists, unsaturated fatty acids, tumour necrosis factor-α (TNFα), insulin or growth hormone (GH) for 6h and LXR expression was analyzed. Lipolysis was measured after incubation with one of the LXR agonists and LXR expression was compared with levels of lipolysis. LXR expression was also analyzed during the differentiation of adipocytes in culture. The incubations with agonists in isolated adipocytes indicated that ATP-binding cassette transporter A1 (ABCA1) is an LXR target gene, but lipoprotein lipase (LPL), fatty acid synthase (FAS), hormone-sensitive lipase (HSL) and peroxisome proliferator-activated receptor (PPARs) are not. LXR agonists also induced LXR expression and raised lipolysis levels. Besides, LXR expression was upregulated in parallel with basal lipolysis. LXR mRNA expression was regulated by unsaturated fatty acids, insulin, TNFα and GH in isolated adipocytes. Besides, LXR showed an upregulation during adipocyte differentiation. All these data indicate that LXR is involved in orchestrating the transcriptional regulatory network in trout adipocyte lipid metabolism, specifically, in cholesterol transport, adipocyte differentiation and lipolysis.
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Affiliation(s)
- Lourdes Cruz-Garcia
- Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
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Suagee JK, Corl BA, Geor RJ. A Potential Role for Pro-Inflammatory Cytokines in the Development of Insulin Resistance in Horses. Animals (Basel) 2012; 2:243-60. [PMID: 26486919 PMCID: PMC4494330 DOI: 10.3390/ani2020243] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 04/16/2012] [Accepted: 04/26/2012] [Indexed: 02/07/2023] Open
Abstract
Insulin resistance is a metabolic condition involving reduced sensitivity of insulin-sensitive tissues to insulin-induced glucose disposal, including adipose tissue, skeletal muscle, and liver. Insulin resistance occurs in overweight and obese horses, and may increase risk for the development of laminitis. The development of insulin resistance is thought to occur in response to increased production of pro-inflammatory cytokines by adipose tissue in obesity, that then have an inhibitory effect on insulin signaling pathways in multiple tissues. This article reviews current knowledge of the involvement of pro-inflammatory cytokines in the development of insulin resistance in horses and uses data from other species to provide context. Understanding the mechanisms involved in the development of insulin resistance in horses should enable development of effective treatment and prevention strategies. Current knowledge of these mechanisms is based upon research in obese humans and rodents, in which there is evidence that the increased production of pro-inflammatory cytokines by adipose tissue negatively influences insulin signaling in insulin-responsive tissues. In horses, plasma concentrations of the cytokine, tumor necrosis factor-α, have been positively correlated with body fatness and insulin resistance, leading to the hypothesis that inflammation may reduce insulin sensitivity in horses. However, little evidence has documented a tissue site of production and a direct link between inflammation and induction of insulin resistance has not been established. Several mechanisms are reviewed in this article, including the potential for macrophage infiltration, hyperinsulinemia, hypoxia, and lipopolysaccharide to increase pro-inflammatory cytokine production by adipose tissue of obese horses. Clearly defining the role of cytokines in reduced insulin sensitivity of horses will be a very important step in determining how obesity and insulin resistance are related.
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Affiliation(s)
- Jessica K Suagee
- Department of Dairy Science, Virginia Tech, Blacksburg, VA 24071, USA.
| | - Benjamin A Corl
- Department of Dairy Science, Virginia Tech, Blacksburg, VA 24071, USA.
| | - Raymond J Geor
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824, USA.
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Yu X, Shen N, Zhang ML, Pan FY, Wang C, Jia WP, Liu C, Gao Q, Gao X, Xue B, Li CJ. Egr-1 decreases adipocyte insulin sensitivity by tilting PI3K/Akt and MAPK signal balance in mice. EMBO J 2011; 30:3754-65. [PMID: 21829168 PMCID: PMC3173797 DOI: 10.1038/emboj.2011.277] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 06/29/2011] [Indexed: 01/09/2023] Open
Abstract
It is well known that insulin can activate both PI3K/Akt pathway, which is responsible for glucose uptake, and MAPK pathway, which is crucial for insulin resistance formation. But, it is unclear exactly how the two pathways coordinate to regulate insulin sensitivity upon hyperinsulinism stress of type 2 diabetes mellitus (T2DM). Here, we show that an early response transcription factor Egr-1 could tilt the signalling balance by blocking PI3K/Akt signalling through PTEN and augmenting Erk/MAPK signalling through GGPPS, resulting in insulin resistance in adipocytes. Egr-1, PTEN and GGPPS are upregulated in the fat tissue of T2DM patients and db/db mice. Egr-1 overexpression in epididymal fat induced systematic insulin resistance in wild-type mice, and loss of Egr-1 function improved whole-body insulin sensitivity in diabetic mice, which is mediated by Egr-1 controlled PI3K/Akt and Erk/MAPK signalling balance. Therefore, we have revealed, for the first time, the mechanism by which Egr-1 induces insulin resistance under hyperinsulinism stress, which provides an ideal pharmacological target since inhibiting Egr-1 can simultaneously block MAPK and augment PI3K/Akt activation during insulin stimulation.
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Affiliation(s)
- Xiao Yu
- MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing, China
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Nishizawa H, Ota S, Suzuki M, Kato T, Sekiya T, Kurahashi H, Udagawa Y. Comparative gene expression profiling of placentas from patients with severe pre-eclampsia and unexplained fetal growth restriction. Reprod Biol Endocrinol 2011; 9:107. [PMID: 21810232 PMCID: PMC3199758 DOI: 10.1186/1477-7827-9-107] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 08/02/2011] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND It has been well documented that pre-eclampsia and unexplained fetal growth restriction (FGR) have a common etiological background, but little is known about their linkage at the molecular level. The aim of this study was to further investigate the mechanisms underlying pre-eclampsia and unexplained FGR. METHODS We analyzed differentially expressed genes in placental tissue from severe pre-eclamptic pregnancies (n = 8) and normotensive pregnancies with or (n = 8) without FGR (n = 8) using a microarray method. RESULTS A subset of the FGR samples showed a high correlation coefficient overall in the microarray data from the pre-eclampsia samples. Many genes that are known to be up-regulated in pre-eclampsia are also up-regulated in FGR, including the anti-angiogenic factors, FLT1 and ENG, believed to be associated with the onset of maternal symptoms of pre-eclampsia. A total of 62 genes were found to be differentially expressed in both disorders. However, gene set enrichment analysis for these differentially expressed genes further revealed higher expression of TP53-downstream genes in pre-eclampsia compared with FGR. TP53-downstream apoptosis-related genes, such as BCL6 and BAX, were found to be significantly more up-regulated in pre-eclampsia than in FGR, although the caspases are expressed at equivalent levels. CONCLUSIONS Our current data indicate a common pathophysiology for FGR and pre-eclampsia, leading to an up-regulation of placental anti-angiogenic factors. However, our findings also suggest that it may possibly be the excretion of these factors into the maternal circulation through the TP53-mediated early-stage apoptosis of trophoblasts that leads to the maternal symptoms of pre-eclampsia.
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Affiliation(s)
- Haruki Nishizawa
- Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake, Japan
| | - Sayuri Ota
- Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan
| | - Machiko Suzuki
- Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan
| | - Takema Kato
- Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan
| | - Takao Sekiya
- Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake, Japan
| | - Hiroki Kurahashi
- Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan
| | - Yasuhiro Udagawa
- Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake, Japan
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Pinent M, Prokesch A, Hackl H, Voshol PJ, Klatzer A, Walenta E, Panzenboeck U, Kenner L, Trajanoski Z, Hoefler G, Bogner-Strauss JG. Adipose triglyceride lipase and hormone-sensitive lipase are involved in fat loss in JunB-deficient mice. Endocrinology 2011; 152:2678-89. [PMID: 21540289 PMCID: PMC3152802 DOI: 10.1210/en.2010-1477] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Proteins of the activator protein-1 family are known to have roles in many physiological processes such as proliferation, apoptosis, and inflammation. However, their role in fat metabolism has yet to be defined in more detail. Here we study the impact of JunB deficiency on the metabolic state of mice. JunB knockout (JunB-KO) mice show markedly decreased weight gain, reduced fat mass, and a low survival rate compared with control mice. If fed a high-fat diet, the weight gain of JunB-KO mice is comparable to control mice and the survival rate improves dramatically. Along with normal expression of adipogenic marker genes in white adipose tissue (WAT) of JunB-KO mice, this suggests that adipogenesis per se is not affected by JunB deficiency. This is supported by in vitro data, because neither JunB-silenced 3T3-L1 cells nor mouse embryonic fibroblasts from JunB-KO mice show a change in adipogenic potential. Interestingly, the key enzymes of lipolysis, adipose triglyceride lipase and hormone-sensitive lipase, were significantly increased in WAT of fasted JunB-KO mice. Concomitantly, the ratio of plasma free fatty acids per gram fat mass was increased, suggesting an elevated lipolytic rate under fasting conditions. Furthermore, up-regulation of TNFα and reduced expression of perilipin indicate that this pathway is also involved in increased lipolytic rate in these mice. Additionally, JunB-KO mice are more insulin sensitive than controls and show up-regulation of lipogenic genes in skeletal muscle, indicating a shuttling of energy substrates from WAT to skeletal muscle. In summary, this study provides valuable insights into the impact of JunB deficiency on the metabolic state of mice.
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Affiliation(s)
- Montserrat Pinent
- Institute for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
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Kashiwada M, Cassel SL, Colgan JD, Rothman PB. NFIL3/E4BP4 controls type 2 T helper cell cytokine expression. EMBO J 2011; 30:2071-82. [PMID: 21499227 DOI: 10.1038/emboj.2011.111] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 03/17/2011] [Indexed: 12/21/2022] Open
Abstract
Type 2 T helper (T(H)2) cells are critical for the development of allergic immune responses; however, the molecular mechanism controlling their effector function is still largely unclear. Here, we report that the transcription factor NFIL3/E4BP4 regulates cytokine production and effector function by T(H)2 cells. NFIL3 is highly expressed in T(H)2 cells but much less in T(H)1 cells. Production of interleukin (IL)-13 and IL-5 is significantly increased in Nfil3(-/-) T(H)2 cells and is decreased by expression of NFIL3 in wild-type T(H)2 cells. NFIL3 directly binds to and negatively regulates the Il13 gene. In contrast, IL-4 production is decreased in Nfil3(-/-) T(H)2 cells. Increased IL-13 and IL-5 together with decreased IL-4 production by antigen-stimulated splenocytes from the immunized Nfil3(-/-) mice was also observed. The ability of NFIL3 to alter T(H)2 cytokine production is a T-cell intrinsic effect. Taken together, these data indicate that NFIL3 is a key regulator of T(H)2 responses.
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Affiliation(s)
- Masaki Kashiwada
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
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Meijer K, de Vries M, Al-Lahham S, Bruinenberg M, Weening D, Dijkstra M, Kloosterhuis N, van der Leij RJ, van der Want H, Kroesen BJ, Vonk R, Rezaee F. Human primary adipocytes exhibit immune cell function: adipocytes prime inflammation independent of macrophages. PLoS One 2011; 6:e17154. [PMID: 21448265 PMCID: PMC3063154 DOI: 10.1371/journal.pone.0017154] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Accepted: 01/03/2011] [Indexed: 11/18/2022] Open
Abstract
Background Obesity promotes inflammation in adipose tissue (AT) and this is implicated in pathophysiological complications such as insulin resistance, type 2 diabetes and cardiovascular disease. Although based on the classical hypothesis, necrotic AT adipocytes (ATA) in obese state activate AT macrophages (ATM) that then lead to a sustained chronic inflammation in AT, the link between human adipocytes and the source of inflammation in AT has not been in-depth and systematically studied. So we decided as a new hypothesis to investigate human primary adipocytes alone to see whether they are able to prime inflammation in AT. Methods and Results Using mRNA expression, human preadipocytes and adipocytes express the cytokines/chemokines and their receptors, MHC II molecule genes and 14 acute phase reactants including C-reactive protein. Using multiplex ELISA revealed the expression of 50 cytokine/chemokine proteins by human adipocytes. Upon lipopolysaccharide stimulation, most of these adipocyte-associated cytokines/chemokines and immune cell modulating receptors were up-regulated and a few down-regulated such as (ICAM-1, VCAM-1, MCP-1, IP-10, IL-6, IL-8, TNF-α and TNF-β highly up-regulated and IL-2, IL-7, IL-10, IL-13 and VEGF down-regulated. In migration assay, human adipocyte-derived chemokines attracted significantly more CD4+ T cells than controls and the number of migrated CD4+ cells was doubled after treating the adipocytes with LPS. Neutralizing MCP-1 effect produced by adipocytes reduced CD4+ migration by approximately 30%. Conclusion Human adipocytes express many cytokines/chemokines that are biologically functional. They are able to induce inflammation and activate CD4+ cells independent of macrophages. This suggests that the primary event in the sequence leading to chronic inflammation in AT is metabolic dysfunction in adipocytes, followed by production of immunological mediators by these adipocytes, which is then exacerbated by activated ATM, activation and recruitment of immune cells. This study provides novel knowledge about the prime of inflammation in human obese adipose tissue, opening a new avenue of investigations towards obesity-associated type 2 diabetes.
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Affiliation(s)
- Kees Meijer
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marcel de Vries
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Saad Al-Lahham
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marcel Bruinenberg
- Department of Medical Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Desirée Weening
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Martijn Dijkstra
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Niels Kloosterhuis
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Roelof Jan van der Leij
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Han van der Want
- Cell Biology, Center for Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Bart-Jan Kroesen
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Roel Vonk
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Farhad Rezaee
- Center for Medical Biomics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- * E-mail:
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Transcriptional control of adipose lipid handling by IRF4. Cell Metab 2011; 13:249-59. [PMID: 21356515 PMCID: PMC3063358 DOI: 10.1016/j.cmet.2011.02.005] [Citation(s) in RCA: 438] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 11/12/2010] [Accepted: 02/10/2011] [Indexed: 11/22/2022]
Abstract
Adipocytes store triglyceride during periods of nutritional affluence and release free fatty acids during fasting through coordinated cycles of lipogenesis and lipolysis. While much is known about the acute regulation of these processes during fasting and feeding, less is understood about the transcriptional basis by which adipocytes control lipid handling. Here, we show that interferon regulatory factor 4 (IRF4) is a critical determinant of the transcriptional response to nutrient availability in adipocytes. Fasting induces IRF4 in an insulin- and FoxO1-dependent manner. IRF4 is required for lipolysis, at least in part due to direct effects on the expression of adipocyte triglyceride lipase and hormone-sensitive lipase. Conversely, reduction of IRF4 enhances lipid synthesis. Mice lacking adipocyte IRF4 exhibit increased adiposity and deficient lipolysis. These studies establish a link between IRF4 and the disposition of calories in adipose tissue, with consequences for systemic metabolic homeostasis.
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25
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Shen N, Yu X, Pan FY, Gao X, Xue B, Li CJ. An early response transcription factor, Egr-1, enhances insulin resistance in type 2 diabetes with chronic hyperinsulinism. J Biol Chem 2011; 286:14508-15. [PMID: 21321112 DOI: 10.1074/jbc.m110.190165] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
One of the most important characteristics of type 2 diabetes is insulin resistance, during which the patients normally experienced hyperinsulinism stress that would alter insulin signal transduction in insulin target tissues. We have previously found that early growth responsive gene-1 (Egr-1), a zinc finger transcription factor, is highly expressed in db/db mice and in the fat tissue of individuals with type 2 diabetes. In this report, we found that chronic exposure to hyperinsulinism caused persistent Erk/MAPK activity in adipocytes and enhanced insulin resistance in an Egr-1-dependent manner. An elevation in Egr-1 augmented Erk1/2 activation via geranylgeranyl diphosphate synthase (GGPPS). Egr-1-promoted GGPPS transcription increased Ras prenylation and caused Erk1/2 activation. The sustained activation of Erk1/2 resulted in the phosphorylation of insulin receptor substrate-1 at Serine 612. Phosphorylation at this site impaired insulin signaling in adipocytes and reduced glucose uptake. The loss of Egr-1 function, knockdown of GGPPS, or inhibition of Erk1/2 activity in insulin-resistant adipocytes restored insulin receptor substrate-1 tyrosine phosphorylation and increased insulin sensitivity. Our results suggest a new mechanism by which the Egr-1/GGPPS/Erk1/2 pathway is responsible for insulin resistance during hyperinsulinism. This pathway provides a new therapeutic target for increasing insulin sensitivity: inhibiting the function of Egr-1.
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Affiliation(s)
- Ning Shen
- Ministry of Education Key Laboratory of Model Animals for Disease Study, Model Animal Research Center and the Medical School of Nanjing University, Nanjing 210061, China
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Kim E. Insulin resistance at the crossroads of metabolic syndrome: systemic analysis using microarrays. Biotechnol J 2010; 5:919-29. [PMID: 20669253 DOI: 10.1002/biot.201000048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recently, it has been suggested that insulin resistance is a better predictor of metabolic syndrome than obesity. Numerous studies have been conducted to identify insulin resistance susceptibility genes in various model systems. This review focuses on recent findings in microarray analyses, which have indicated that (i) in the liver, genes involved in lipid synthesis and gluconeogenesis are increased in an animal model of insulin resistance that leads into liver steatosis and hyperglycemia; (ii) in adipose tissues, genes involved in fatty acid synthesis and adipogenesis are down-regulated both in insulin-resistant humans and in animals; and (iii) in muscle, overall gene expression, including genes involved in fatty acid oxidation and biosynthesis, is either decreased or unresponsive compared to that of insulin-sensitive control human subjects or animals. Considering the multifaceted effects of insulin resistance in various tissues, aiming at multi-targets rather than a single target will be a more promising strategy for the prevention or treatment of insulin resistance.
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Affiliation(s)
- Eunjung Kim
- Department of Food Sciences and Nutrition, Catholic University of Daegu, Gyeongsan, Food and Nutritional Genomics Research Center, Kyungpook National University, Daegu, Republic of Korea.
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Dray C, Debard C, Jager J, Disse E, Daviaud D, Martin P, Attané C, Wanecq E, Guigné C, Bost F, Tanti JF, Laville M, Vidal H, Valet P, Castan-Laurell I. Apelin and APJ regulation in adipose tissue and skeletal muscle of type 2 diabetic mice and humans. Am J Physiol Endocrinol Metab 2010; 298:E1161-9. [PMID: 20233941 DOI: 10.1152/ajpendo.00598.2009] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Apelin, an adipocyte-secreted factor upregulated by insulin, is increased in adipose tissue (AT) and plasma with obesity. Apelin was recently identified as a new player in the control of glucose homeostasis. However, the regulation of apelin and APJ (apelin receptor) expression in skeletal muscle in relation to insulin resistance or type 2 diabetes is not known. Thus we studied apelin and APJ expression in AT and muscle in different mice models of obesity and in type 2 diabetic patients. In insulin-resistant high-fat (HF)-fed mice, apelin and APJ expression were increased in AT compared with control. This was not the case in AT of highly insulin-resistant db/db mice. In skeletal muscle, apelin expression was similar in control and HF-fed mice and decreased in db/db mice. APJ expression was decreased in both HF-fed and db/db mice. Control subjects and type 2 diabetic patients were subjected to a hyperinsulinemic-euglycemic clamp, and tissues biopsies were obtained before and at the end of the clamp. There was no significant difference in basal apelin and APJ expression in AT and muscle between control and diabetic patients. However, apelin plasma levels were significantly increased in diabetic patients. During the clamp, hyperinsulinemia increased apelin and APJ expression in AT of control but not in diabetic subjects. In muscle, only APJ mRNA levels were increased in control but also in diabetic patients. Taken together, these data show that apelin and APJ expression in mice and humans is regulated in a tissue-dependent manner and according to the severity of insulin resistance.
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Affiliation(s)
- Cédric Dray
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 858, Toulouse, France
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Mukesh M, Bionaz M, Graugnard DE, Drackley JK, Loor JJ. Adipose tissue depots of Holstein cows are immune responsive: inflammatory gene expression in vitro. Domest Anim Endocrinol 2010; 38:168-78. [PMID: 19914024 DOI: 10.1016/j.domaniend.2009.10.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 09/20/2009] [Accepted: 10/06/2009] [Indexed: 10/20/2022]
Abstract
The transcriptional response of adipose tissue depots with respect to their immune responsiveness in dairy cows remains largely unknown. Thus, we examined mRNA expression and responsiveness of subcutaneous (SUB) and mesenteric (MES) adipose tissue from nonpregnant dairy cows to a short-term (2 h), in vitro lipopolysaccharide (LPS) challenge (20 microg/mL in physiological saline). Abundance of mRNA for tumor necrosis factor-alpha (TNFA), interleukin-6 (IL6), serum amyloid A3 (SAA3), toll-like receptor 4 (TLR4), monocyte chemoattractant protein-1 (CCL2), and RANTES/chemokine C-C motif ligand 5 (CCL5) were analyzed using quantitative polymerase chain reaction (PCR) from tissue samples collected at slaughter from 5 nonpregnant/nonlactating Holstein cows. Prior to LPS challenge, SAA3 mRNA abundance was greater in MES than SUB tissue. Regardless of depot site, LPS led to greater mRNA abundance of TNFA and IL6 and was more pronounced for IL6 in MES. We also observed a marked increased in expression of CCL2, CCL5, TLR4, IL6, and TNFA in both MES and SUB during the 2-h incubation with saline alone (ie, the control). Because mRNA expression of the apoptotic markers B-cell CLL/lymphoma 2 (BCL2) and tumor protein p53 (TP53) did not differ during the 2-h incubation, it is less likely that the response to saline was a result of increased rate of cell death during incubation. Analysis using semiquantitative PCR of the 16s rRNA gene in cDNA from tissue explants revealed the presence of bacteria likely arising from contamination during sample collection. Furthermore, surfactant medium from about 50% of explant cultures had viable aerobic bacteria without differences between treatments or tissue samples. Thus, the presence of bacteria could partly explain the large increase in inflammatory-related genes after 2-h incubation with saline. The higher SAA3 expression in MES suggests that this acute-phase protein has a role in lipid metabolism and/or transport during an immune challenge. Overall, results provided evidence that adipose depots of dairy cows are capable of synthesizing chemokines and are immune responsive when exposed to inflammatory conditions that can arise from a pathogenic insult or during and soon after parturition.
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Affiliation(s)
- M Mukesh
- Mammalian NutriPhysioGenomics, University of Illinois, Urbana, IL 61801, USA
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29
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IL-4-induced transcription factor NFIL3/E4BP4 controls IgE class switching. Proc Natl Acad Sci U S A 2009; 107:821-6. [PMID: 20080759 DOI: 10.1073/pnas.0909235107] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
IL-4 signaling promotes IgE class switching through STAT6 activation and the induction of Ig germ-line epsilon (GLepsilon) transcription. Previously, we and others identified a transcription factor, Nfil3, as a gene induced by IL-4 stimulation in B cells. However, the precise roles of nuclear factor, IL-3-regulated (NFIL3) in IL-4 signaling are unknown. Here, we report that NFIL3 is important for IgE class switching. NFIL3-deficient mice show impaired IgE class switching, and this defect is B-cell intrinsic. The induction of GLepsilon transcripts after LPS and IL-4 stimulation is significantly reduced in NFIL3-deficient B cells. Expression of NFIL3 in NFIL3-deficient B cells restores the impairment of IgE production, and overexpression of NFIL3 in the presence of cycloheximide induces GLepsilon transcripts. Moreover, NFIL3 binds to Iepsilon promoter in vivo. Together, these results identify NFIL3 as a key regulator of IL-4-induced GLepsilon transcription in response to IL-4 and subsequent IgE class switching.
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Abstract
PURPOSE OF REVIEW It has recently been recognized that cholesterol homeostasis is fundamentally important for appropriate insulin secretory function of beta-cells in the pancreas. This review summarizes recent advances in understanding the relationship between beta-cell cholesterol metabolism and beta-cell function. RECENT FINDINGS The accumulation of cholesterol in beta-cells causes perturbations in glucose metabolism, reduces insulin secretion and can be associated with a diabetic phenotype. Cholesterol is also a key determinant of beta-cell membrane organization and cell survival. The ATP-binding cassette transporter A1, which effluxes cholesterol to lipid-free/lipid-poor apolipoprotein A-I, the principal apolipoprotein in HDLs, is crucial for maintaining beta-cell cholesterol homeostasis and function. There is also evidence suggesting that different lipoprotein classes have varying effects on beta-cell function and survival. SUMMARY Cholesterol is important for beta-cell function and survival. It can cause beta-cell loss if allowed to accumulate in the cells in an unregulated manner. The maintenance of beta-cell cholesterol homeostasis, therefore, is important for preventing beta-cell dysfunction, the onset of insulin resistance and the development of type 2 diabetes.
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Affiliation(s)
- Michelle Fryirs
- Lipid Research Group, The Heart Research Institute, New South Wales, Australia
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Kim JY, Liu K, Zhou S, Tillison K, Wu Y, Smas CM. Assessment of fat-specific protein 27 in the adipocyte lineage suggests a dual role for FSP27 in adipocyte metabolism and cell death. Am J Physiol Endocrinol Metab 2008; 294:E654-67. [PMID: 18198355 DOI: 10.1152/ajpendo.00104.2007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fat-specific protein 27 (FSP27)/CIDEC was initially identified by its upregulation in TA1 adipogenesis and is one of three cell death-inducing DFF45-like effector (CIDE) family proapoptotic proteins. Ectopic expression of CIDEs promotes apoptosis of mammalian cells. On the other hand, FSP27 has very recently been illustrated to regulate lipid droplet size and promote lipid storage in adipocytes. Regulation of endogenous FSP27 expression is unknown. We assessed the FSP27 transcript level in the well-characterized 3T3-L1 in vitro adipocyte differentiation model and found its emergence parallels the adipocyte-enriched transcript adipocyte fatty acid binding protein and stearoyl Co-A desaturase 1. Furthermore, FSP27 is a differentiation-dependent transcript in adipogenesis of primary rodent and human preadipocytes and in brown adipogenesis. The FSP27 transcript is inversely regulated by TNF-alpha and insulin, consistent with an antilipolytic function. It is nearly abolished with a 4-h exposure of 3T3-L1 adipocytes to 10 ng/ml TNF-alpha, while treatment with 100 nM insulin increased the FSP27 transcript eightfold. In the latter case LY-294002 blocked this response, indicating involvement of phosphatidylinositol 3-kinase signals. Northern blot analysis of murine tissues indicated exclusive expression of FSP27 in white and brown adipose tissue; however, a dramatic upregulation occurred in the liver of ob/ob mice. Ectopic expression of murine FSP27 in 293T cells and in 3T3-L1 preadipocytes led to the appearance of key apoptotic hallmarks and cell death. However, despite the upregulation for FSP27 in adipogenesis, we failed to detect DNA laddering indicative of apoptosis in 3T3-L1 adipocytes. This suggests that adipogenesis is accompanied by decreased susceptibility to the proapoptotic effects of FSP27. Overall, our findings support roles for FSP27 in cell death and in adipocyte function.
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Affiliation(s)
- Ji Young Kim
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Toledo, OH 43614, USA
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32
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Brunham LR, Kruit JK, Verchere CB, Hayden MR. Cholesterol in islet dysfunction and type 2 diabetes. J Clin Invest 2008; 118:403-8. [PMID: 18246189 DOI: 10.1172/jci33296] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Type 2 diabetes (T2D) frequently occurs in the context of abnormalities of plasma lipoproteins. However, a role for elevated levels of plasma cholesterol in the pathogenesis of this disease is not well established. Recent evidence suggests that alterations of plasma and islet cholesterol levels may contribute to islet dysfunction and loss of insulin secretion. A number of genes involved in lipid metabolism have been implicated in T2D. Recently an important role for ABCA1, a cellular cholesterol transporter, has emerged in regulating cholesterol homeostasis and insulin secretion in pancreatic beta cells. Here we review the impact of cholesterol metabolism on islet function and its potential relationship to T2D.
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Affiliation(s)
- Liam R Brunham
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
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33
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Villarreal-Molina MT, Flores-Dorantes MT, Arellano-Campos O, Villalobos-Comparan M, Rodríguez-Cruz M, Miliar-García A, Huertas-Vazquez A, Menjivar M, Romero-Hidalgo S, Wacher NH, Tusie-Luna MT, Cruz M, Aguilar-Salinas CA, Canizales-Quinteros S. Association of the ATP-binding cassette transporter A1 R230C variant with early-onset type 2 diabetes in a Mexican population. Diabetes 2008; 57:509-13. [PMID: 18003760 DOI: 10.2337/db07-0484] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The ATP-binding cassette transporter A1 (ABCA1) R230C variant is associated with low HDL cholesterol levels, obesity, and the metabolic syndrome in Mexican-Mestizos. Because a pivotal role for ABCA1 in pancreatic beta-cell function was recently observed in the mouse model, we assessed the association of this variant with type 2 diabetes in this population. RESEARCH DESIGN AND METHODS The initial group included 446 unrelated Mexican individuals: 244 with type 2 diabetes aged 20-69 years (121 with onset </=45 years), and 202 nondiabetic control subjects aged >50 years. An independent study group included 242 type 2 diabetic case subjects and 225 control subjects with similar characteristics. RESULTS R230C/C230C genotypes were significantly more frequent in type 2 diabetic individuals (24.6%) than in control subjects (11.4%) in the initial study group (OR 2.501; P = 0.001). After stratifying by age at diagnosis, the association was significant only in the early-onset group (age at diagnosis </=45 years) (OR 3.776, P = 3.3 x 10(-6)). Both associations remained significant after adjusting for admixture (P = 0.0008 and P = 8.1 x 10(-6), respectively). Similar trends were observed in the independent study group, and the combined analysis of both populations showed a highly significant association of the R230C variant with type 2 diabetes, particularly with that of early onset (P = 7.6 x 10(-6) and 9.4 x 10(-8), respectively). CONCLUSIONS The R230C ABCA1 variant is associated with type 2 diabetes, particularly of early onset, in the Mexican-Mestizo population.
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Affiliation(s)
- M Teresa Villarreal-Molina
- Unidad de Biología Molecular y Medicina Genómica, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga #15 Colonia Sección 16, Tlalpan 14000, México D.F
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Sakurai T, Takei M, Ogasawara J, Ueda H, Kizaki T, Ohno H, Izawa T. Exercise before or after refeeding prevents refeeding-induced recovery of cell size after fasting with a different pattern of metabolic gene expressions in rat epididymal adipocytes. Metabolism 2007; 56:1270-8. [PMID: 17697872 DOI: 10.1016/j.metabol.2007.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2006] [Accepted: 05/15/2007] [Indexed: 11/25/2022]
Abstract
We investigated the effect of exercise before or after refeeding on cell size and on the expression of several messenger RNAs (mRNAs) involved in lipolysis and lipogenesis in fasted rat epididymal adipocytes. Fasting for 65 hours reduced the diameter of adipocytes to 72.0 microm from 78.4 microm in fed control rats, whereas refeeding for 1 or 2 days restored adipocyte size to 74.0 or 75.8 microm, respectively. Exercise before or after refeeding blocked refeeding-induced restoration of adipocyte size and led to adipocyte size similar to that observed after fasting. Fasting dramatically reduced expression of the fatty acid synthase mRNA, although expression of this gene returned to the control level after refeeding. However, exercise after but not before refeeding inhibited recovery of the expression of fatty acid synthase mRNA resulting from refeeding. In contrast, exercise before but not after refeeding led to enhanced expression of mRNAs encoding the hormone-sensitive lipase and beta(3)-aderenoceptor. Thus, exercise before or after refeeding prevents refeeding-induced restoration of adipocyte size after fasting via different pathways. Exercise before and after refeeding enhanced the expression of lipolytic mRNAs or inhibited the expression of lipogenic mRNAs, respectively.
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Affiliation(s)
- Takuya Sakurai
- Department of Kinesiology, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan
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35
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Villarreal-Molina MT, Aguilar-Salinas CA, Rodríguez-Cruz M, Riaño D, Villalobos-Comparan M, Coral-Vazquez R, Menjivar M, Yescas-Gomez P, Königsoerg-Fainstein M, Romero-Hidalgo S, Tusie-Luna MT, Canizales-Quinteros S. The ATP-binding cassette transporter A1 R230C variant affects HDL cholesterol levels and BMI in the Mexican population: association with obesity and obesity-related comorbidities. Diabetes 2007; 56:1881-7. [PMID: 17287470 DOI: 10.2337/db06-0905] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Although ATP-binding cassette transporter A1 (ABCA1) is well known for its role in cholesterol efflux and HDL formation, it is expressed in various tissues, where it may have different functions. Because hypoalphalipoproteinemia is highly prevalent in Mexico, we screened the ABCA1 coding sequence in Mexican individuals with low and high HDL cholesterol levels to seek functional variants. A highly frequent nonsynonymous variant (R230C) was identified in low-HDL cholesterol but not in high-HDL cholesterol individuals (P = 0.00006). We thus assessed its frequency in the Mexican-Mestizo general population, seeking possible associations with several metabolic traits. R230C was screened in 429 Mexican Mestizos using Taqman assays, and it was found in 20.1% of these individuals. The variant was significantly associated not only with decreased HDL cholesterol and apolipoprotein A-I levels but also with obesity (odds ratio 2.527, P = 0.005), the metabolic syndrome (1.893, P = 0.0007), and type 2 diabetes (4.527, P = 0.003). All of these associations remained significant after adjusting for admixture (P = 0.011, P = 0.001, and P = 0.006, respectively). This is the first study reporting the association of an ABCA1 variant with obesity and obesity-related comorbidities as being epidemiologically relevant in the Mexican population.
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Affiliation(s)
- M Teresa Villarreal-Molina
- Unit of Molecular Biology and Genomic Medicine, Salvador Zubiran National Institute of Medical Sciences and Nutrition (INCMNSZ), National Autonomous University of Mexico, Mexico City, Mexico
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Vastrik I, D'Eustachio P, Schmidt E, Joshi-Tope G, Gopinath G, Croft D, de Bono B, Gillespie M, Jassal B, Lewis S, Matthews L, Wu G, Birney E, Stein L. Reactome: a knowledge base of biologic pathways and processes. Genome Biol 2007; 8:R39. [PMID: 17367534 PMCID: PMC1868929 DOI: 10.1186/gb-2007-8-3-r39] [Citation(s) in RCA: 409] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 12/19/2006] [Accepted: 03/16/2007] [Indexed: 11/16/2022] Open
Abstract
Reactome, an online curated resource for human pathway data, can be used to infer equivalent reactions in non-human species and as a tool to aid in the interpretation of microarrays and other high-throughput data sets. Reactome http://www.reactome.org, an online curated resource for human pathway data, provides infrastructure for computation across the biologic reaction network. We use Reactome to infer equivalent reactions in multiple nonhuman species, and present data on the reliability of these inferred reactions for the distantly related eukaryote Saccharomyces cerevisiae. Finally, we describe the use of Reactome both as a learning resource and as a computational tool to aid in the interpretation of microarrays and similar large-scale datasets.
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Affiliation(s)
- Imre Vastrik
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Peter D'Eustachio
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
- NYU School of Medicine, First Avenue, New York, NY 10016, USA
| | - Esther Schmidt
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Geeta Joshi-Tope
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Gopal Gopinath
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - David Croft
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Bernard de Bono
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Marc Gillespie
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
- College of Pharmacy and Allied Health Professions, St. John's University, Utopia Parkway, Queens, NY 11439, USA
| | - Bijay Jassal
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Suzanna Lewis
- Lawrence Berkeley National Laboratory, Cyclotron Road 64R0121, Berkeley, CA 94720, USA
| | - Lisa Matthews
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Guanming Wu
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Ewan Birney
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Lincoln Stein
- Cold Spring Harbor Laboratory, Bungtown Road, Cold Spring Harbor, NY 11724, USA
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Abstract
PURPOSE OF REVIEW Plasminogen activator inhibitor (PAI)-1 is a physiological inhibitor of plasminogen activators (urokinase and tissue types) and vitronectin. It is synthesized by adipose tissue, and its levels in plasma are increased in obesity and reduced with weight loss. Circulating PAI-1 level predicts development of type 2 diabetes, suggesting that it may be causally related to development of obesity. A role for PAI-1 in development of obesity has only partially been established, however. This review summarizes current knowledge, gives context to developments thus far and discusses controversies. RECENT FINDINGS In addition to its role in atherothrombosis, PAI-1 might be involved in adipose tissue development. PAI-1 is produced by ectopic fat depots under the influence of inducers. Among the most recently described inducers are inflammation, oxidative stress and circadian clock protein. PAI-1 may play several roles in contributing to obesity: through indirect effects on insulin signalling, by influencing adipocyte differentiation and by regulating recruitment of inflammatory cells within adipose tissue. SUMMARY These recent findings emphasize the involvement of PAI-1 in controlling the biology of adipose tissue; PAI-1 is an attractive new therapeutic target to retard the metabolic complications that accompany obesity.
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Rowe WB, Blalock EM, Chen KC, Kadish I, Wang D, Barrett JE, Thibault O, Porter NM, Rose GM, Landfield PW. Hippocampal expression analyses reveal selective association of immediate-early, neuroenergetic, and myelinogenic pathways with cognitive impairment in aged rats. J Neurosci 2007; 27:3098-110. [PMID: 17376971 PMCID: PMC6672456 DOI: 10.1523/jneurosci.4163-06.2007] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although expression of some genes is known to change during neuronal activity or plasticity, the overall relationship of gene expression changes to memory or memory disorders is not well understood. Here, we combined extensive statistical microarray analyses with behavioral testing to comprehensively identify genes and pathways associated with aging and cognitive dysfunction. Aged rats were separated into cognitively unimpaired (AU) or impaired (AI) groups based on their Morris water maze performance relative to young-adult (Y) animals. Hippocampal gene expression was assessed in Y, AU, and AI on the fifth (last) day of maze training (5T) or 21 d posttraining (21PT) and in nontrained animals (eight groups total, one array per animal; n = 78 arrays). ANOVA and linear contrasts identified genes that differed from Y generally with aging (differed in both AU and AI) or selectively, with cognitive status (differed only in AI or AU). Altered pathways/processes were identified by overrepresentation analyses of changed genes. With general aging, there was downregulation of axonal growth, cytoskeletal assembly/transport, signaling, and lipogenic/uptake pathways, concomitant with upregulation in immune/inflammatory, lysosomal, lipid/protein degradation, cholesterol transport, transforming growth factor, and cAMP signaling pathways, primarily independent of training condition. Selectively, in AI, there was downregulation at 5T of immediate-early gene, Wnt (wingless integration site), insulin, and G-protein signaling, lipogenesis, and glucose utilization pathways, whereas Notch2 (oligodendrocyte development) and myelination pathways were upregulated, particularly at 21PT. In AU, receptor/signal transduction genes were upregulated, perhaps as compensatory responses. Immunohistochemistry confirmed and extended selected microarray results. Together, the findings suggest a new model, in which deficient neuroenergetics leads to downregulated neuronal signaling and increased glial activation, resulting in aging-related cognitive dysfunction.
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Affiliation(s)
- Wayne B. Rowe
- Department of Functional Neuroscience, Memory Pharmaceuticals Corporation, Montvale, New Jersey 07645
| | - Eric M. Blalock
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky 40536
| | - Kuey-Chu Chen
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky 40536
| | - Inga Kadish
- Department of Cell Biology, University of Alabama, Birmingham, Alabama 35294, and
| | - Daguang Wang
- Department of Functional Neuroscience, Memory Pharmaceuticals Corporation, Montvale, New Jersey 07645
| | | | - Olivier Thibault
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky 40536
| | - Nada M. Porter
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky 40536
| | - Gregory M. Rose
- Department of Functional Neuroscience, Memory Pharmaceuticals Corporation, Montvale, New Jersey 07645
| | - Philip W. Landfield
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, Lexington, Kentucky 40536
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Okamoto Y, Higashiyama H, Rong JX, McVey MJ, Kinoshita M, Asano S, Hansen MK. Comparison of mitochondrial and macrophage content between subcutaneous and visceral fat in db/db mice. Exp Mol Pathol 2007; 83:73-83. [PMID: 17434481 DOI: 10.1016/j.yexmp.2007.02.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Revised: 02/20/2007] [Accepted: 02/20/2007] [Indexed: 10/23/2022]
Abstract
Central (visceral) obesity is more closely associated with insulin resistance, type 2 diabetes, and cardiovascular disease than peripheral (subcutaneous) obesity, however the underlying differences in morphology and pathophysiology between subcutaneous and visceral adipose are largely unknown. To evaluate the effects of diabetes and rosiglitazone (RSG) treatment, the expression of mitochondrial Hsp60, UCP-1 and F4/80 in inguinal subcutaneous (SC) fat, composed of white and brown adipose tissues, and epididymal (EP) fat, mainly white adipose tissue, were evaluated. In diabetic db/db mice, there was significant increased number of aggregated macrophage foci compared to db/+ mice, especially in EP fat. On the other hand, the expression of mitochondrial Hsp60 protein was suppressed in both SC and EP fat of db/db mice compared to db/+ mice, and the expression level of mitochondrial Hsp60 in db/+ mice was lower in EP fat compared with SC. In db/db mice, RSG suppressed the number of aggregated macrophage foci in EP fat, but not in SC fat. RSG ameliorated the mitochondrial Hsp60 expression and induced the expression of UCP-1 in both SC and EP fat. Taken together, these data suggest that differences exist in mitochondrial and macrophage content, and in the response to RSG between visceral and subcutaneous adipose tissue, and adipose type and distribution may be important for obesity-linked insulin resistance.
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Affiliation(s)
- Yuji Okamoto
- Development and Medical Affairs Division, GlaxoSmithKline, 4-6-15 Sendagaya, Shibuya-ku, Tokyo 151-8566, Japan
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40
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Moloney F, Toomey S, Noone E, Nugent A, Allan B, Loscher CE, Roche HM. Antidiabetic effects of cis-9, trans-11-conjugated linoleic acid may be mediated via anti-inflammatory effects in white adipose tissue. Diabetes 2007; 56:574-82. [PMID: 17327424 DOI: 10.2337/db06-0384] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Adipose tissue may be the source of insulin desensitizing proinflammatory molecules that predispose to insulin resistance. This study investigated whether dietary fatty acids could attenuate the proinflammatory insulin-resistant state in obese adipose tissue. The potential antidiabetic effect of cis-9, trans-11-conjugated linoleic acid (c9,t11-CLA) was determined, focusing on the molecular markers of insulin sensitivity and inflammation in adipose tissue of ob/ob C57BL-6 mice. Feeding a c9,t11-CLA-enriched diet reduced fasting glucose (P < 0.05), insulin (P < 0.05), and triacylglycerol concentrations (P < 0.01) and increased adipose tissue plasma membrane GLUT4 (P < 0.05) and insulin receptor (P < 0.05) expression compared with the control linoleic acid-enriched diet. Interestingly, after the c9,t11-CLA diet, adipose tissue macrophage infiltration was less, with marked downregulation of several inflammatory markers in adipose tissue, including reduced tumor necrosis factor-alpha and CD68 mRNA (P < 0.05), nuclear factor-kappaB (NF-kappaB) p65 expression (P < 0.01), NF-kappaB DNA binding (P < 0.01), and NF-kappaB p65, p50, c-Rel, p52, and RelB transcriptional activity (P < 0.01). To define whether these observations were direct effects of the nutrient intervention, complimentary cell culture studies showed that c9,t11-CLA inhibited tumor necrosis factor-alpha-induced downregulation of insulin receptor substrate 1 and GLUT4 mRNA expression and promoted insulin-stimulated glucose transport in 3T3-L1 adipocytes compared with linoleic acid. This study suggests that altering fatty acid composition may attenuate the proinflammatory state in adipose tissue that predisposes to obesity-induced insulin resistance.
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Affiliation(s)
- Fiona Moloney
- Nutrigenomics Research Group, Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, St. James's Hospital, Dublin 8, Ireland
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42
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Ornskov D, Nexo E, Sorensen BS. Insulin induces a transcriptional activation of epiregulin, HB-EGF and amphiregulin, by a PI3K-dependent mechanism: identification of a specific insulin-responsive promoter element. Biochem Biophys Res Commun 2007; 354:885-91. [PMID: 17274952 DOI: 10.1016/j.bbrc.2007.01.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 01/10/2007] [Indexed: 11/29/2022]
Abstract
Previously we have shown that insulin-stimulation of RT4 bladder cancer cells leads to increased proliferation, which require HER1 activation, and is accompanied by increased mRNA expression of the EGF-ligands heparin-binding EGF-like growth factor (HB-EGF), amphiregulin (AR), and epiregulin (EPI) [D. Ornskov, E. Nexo, B.S. Sorensen, Insulin-induced proliferation of bladder cancer cells is mediated through activation of the epidermal growth factor system, FEBS J. 273 (2006) 5479-5489]. In the present paper, we have investigated the molecular mechanism leading to this insulin-induced expression. We monitored the decay of mRNA after inhibiting transcription with Actinomycin D and demonstrated that the insulin-mediated increase was not caused by enhanced mRNA stability. In untreated cells, HB-EGF mRNA was the least stable, whereas AR and EPI mRNA decayed with slower kinetics. However, promoter analysis of HB-EGF and EPI demonstrated that insulin stimulated transcription. Studies on the EPI promoter identified the insulin-responsive element to be located in the region -564 to -365bp. This region contains potential binding sites for the transcription factors SP1, AP1, and NF-kappaB. Interestingly, all three transcription factors can be activated by PI3K. We demonstrate that the insulin-induced expression of HB-EGF, AR, and EPI mRNA is completely prevented by the specific PI3K inhibitor Wortmannin, suggesting an involvement of the PI3K.
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Affiliation(s)
- Dorthe Ornskov
- Department of Clinical Biochemistry, Aarhus Sygehus University Hospital in Aarhus, Denmark
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Eto K, Kaur V, Thomas MK. Regulation of pancreas duodenum homeobox-1 expression by early growth response-1. J Biol Chem 2006; 282:5973-83. [PMID: 17150967 DOI: 10.1074/jbc.m607288200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The homeodomain transcription factor pancreas duodenum homeobox-1 (PDX-1) is a key regulator of pancreatic beta-cell development, function, and survival. Deficits in PDX-1 expression result in insulin deficiency and hyperglycemia. We previously found that the glucose-responsive transcription factor early growth response-1 (Egr-1) activates the insulin promoter in part by increasing expression levels of PDX-1. We now report that Egr-1 binds and activates multiple regulatory sites within the pdx-1 promoter. We identified consensus Egr-1 recognition sequences within proximal and distal regions of the mouse pdx-1 promoter and demonstrated specific binding of Egr-1 by chromatin immunoprecipitation and electrophoretic mobility shift assays. Overexpression of Egr-1 increased transcriptional activation of the -4500 proximal pdx-1 promoter and of the highly conserved regulatory Areas I, II, and III. Mutagenesis of a specific Egr-1 binding site within Area III substantially decreased Egr-1-mediated activation. Egr-1 increased the transcriptional activation of Areas I and II, despite the absence of Egr-1 recognition sequences within this promoter segment, suggesting that Egr-1 also can regulate the pdx-1 promoter indirectly. Egr-1 increased, and a dominant-negative Egr-1 mutant repressed, the transcriptional activation of distal pdx-1 promoter sequences. Mutagenesis of a specific Egr-1 binding site within regulatory Area IV reduced basal and Egr-1-mediated transcriptional activation. Our data indicate that Egr-1 regulates expression of PDX-1 in pancreatic beta-cells by both direct and indirect activation of the pdx-1 promoter. We propose that Egr-1 expression levels may act as a sensor in pancreatic beta-cells to translate extracellular signals into changes in PDX-1 expression levels and pancreatic beta-cell function.
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Affiliation(s)
- Kazuhiro Eto
- Laboratory of Molecular Endocrinology and Diabetes Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts 02114, USA
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Ornskov D, Nexo E, Sorensen BS. Insulin-induced proliferation of bladder cancer cells is mediated through activation of the epidermal growth factor system. FEBS J 2006; 273:5479-89. [PMID: 17116246 DOI: 10.1111/j.1742-4658.2006.05539.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism behind the growth-promoting effect of insulin is a subject of debate. Employing RT4 bladder cancer cells, we examined the cross-talk between insulin and the epidermal growth factor system. We found that insulin induced a time- and dose-dependent (25-1000 nmol.L(-1) insulin) increase in mRNA expression of three ligands from the epidermal growth factor system. Times for peak increase and fold increase after incubation with 250 nmol.L(-1) insulin were as follows: heparin-binding epidermal growth factor-like growth factor, 0.5 h, 1.4-fold, P < 0.05; epiregulin, 3 h, 14-fold, P < 0.0001; and amphiregulin, 3 h, 12-fold, P < 0.001. Induction of heparin-binding epidermal growth factor-like growth factor and amphiregulin was verified at the protein level. We demonstrate that incubation of RT4 bladder cancer cells for 24 h with 250 nmol.L(-1) insulin increases proliferation by 43% (P < 0.0001) as compared to untreated cells. At the same time, phosphorylation and thereby activation of the epidermal growth factor receptor (HER1) was observed. Both phosphorylation and insulin-induced proliferation were almost completely inhibited by the HER1 inhibitor Iressa (P < 0.0001). This shows that insulin leads to activation of HER1, and that HER1 plays an essential role in mediating the growth-promoting effect of insulin. Iressa inhibited not only the activation of HER1 caused by insulin but also the insulin-induced increase in the three ligands (heparin-binding epidermal growth factor-like growth factor, epiregulin and amphiregulin). As heparin-binding epidermal growth factor-like growth factor was induced before epiregulin and amphiregulin upon insulin stimulation, we speculated that the insulin-induced heparin-binding epidermal growth factor-like growth factor initiated the activation of HER1, and that this in turn led to increased expression of epiregulin and amphiregulin and thereby to continued activation of HER1. Earlier reports have shown that insulin-like growth factor receptor can activate HER1 via its ligand heparin-binding epidermal growth factor-like growth factor. In accord with this, we found that treatment of RT4 cells with recombinant heparin-binding epidermal growth factor-like growth factor mimicked the effect of insulin, with induction of mRNA for the three ligands. However, the insulin-induced increase in mRNA expression of amphiregulin and epiregulin could not be prevented by the heparin-binding epidermal growth factor-like growth factor inhibitor CRM197, demonstrating that heparin-binding epidermal growth factor-like growth factor is not essential for the insulin-induced increase in the expression of these ligands. In conclusion, we show that insulin-induced growth in RT4 cells requires activated HER1. Furthermore, activation of HER1 is required for the insulin-induced increase in expression of the HER1 ligands heparin-binding epidermal growth factor-like growth factor, amphiregulin and epiregulin.
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Affiliation(s)
- Dorthe Ornskov
- Department of Clinical Biochemistry, Aarhus Sygehus, University Hospital in Aarhus, Denmark
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Porchay I, Péan F, Bellili N, Royer B, Cogneau J, Chesnier MC, Caradec A, Tichet J, Balkau B, Marre M, Fumeron F. ABCA1 single nucleotide polymorphisms on high-density lipoprotein-cholesterol and overweight: the D.E.S.I.R. study. Obesity (Silver Spring) 2006; 14:1874-9. [PMID: 17135600 DOI: 10.1038/oby.2006.217] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The adenosine triphosphate-binding cassette A1 (ABCA1) gene plays a key role in reverse cholesterol transport. Some ABCA1 gene polymorphisms have been associated with high-density lipoprotein-cholesterol (HDL-C) concentrations. The aim of this study was to assess the effect of three polymorphisms, C69T, G378C, and G1051A (R219K), on HDL-C levels and their interaction with BMI in more than 5000 French whites from the D.E.S.I.R. (Data from an Epidemiological Study on the Insulin Resistance syndrome) cohort study. The T allele of the C69T single nucleotide polymorphism (SNP) was associated with higher HDL-C levels in normal-weight men (BMI <25 kg/m(2)). The C allele of the G378C SNP was associated with lower HDL-C in overweight subjects (BMI > or =25 kg/m(2)). For the G1051A SNP, in the normal-weight group, the minor A allele was significantly associated with higher HDL-C levels. In contrast, in overweight people, the minor allele was associated with lower HDL-C levels. After accounting for multiple testing, empiric p values remained significant for the associations between G378C SNP and HDL-C in the overweight group and between G1051A SNP and HDL-C in the normal-weight group. This study suggests that ABCA1 gene polymorphisms modulate HDL-C concentrations, in interaction with BMI, and, thus, they might influence cardiovascular risk in the general population.
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Affiliation(s)
- Isabelle Porchay
- Institut National de la Santé et de la Recherche Médicale, Unité 695, Xavier Bichat School of Medicine, Paris, France
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Abstract
The link between plasminogen activator inhibitor (PAI)-1 and the metabolic syndrome with obesity was established many years ago. Increased PAI-1 level can be now considered a true component of the syndrome. The metabolic syndrome is associated with an increased risk of developing cardiovascular disease, and PAI-1 overexpression may participate in this process. The mechanisms of PAI-1 overexpression during obesity are complex, and it is conceivable that several inducers are involved at the same time at several sites of synthesis. Interestingly, recent in vitro and in vivo studies showed that besides its role in atherothrombosis, PAI-1 is also implicated in adipose tissue development and in the control of insulin signaling in adipocytes. These findings suggest PAI-1 inhibitors serve in the control of atherothrombosis and insulin resistance.
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Samad F, Hester KD, Yang G, Hannun YA, Bielawski J. Altered adipose and plasma sphingolipid metabolism in obesity: a potential mechanism for cardiovascular and metabolic risk. Diabetes 2006; 55:2579-87. [PMID: 16936207 DOI: 10.2337/db06-0330] [Citation(s) in RCA: 230] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The adipose tissue has become a central focus in the pathogenesis of obesity-mediated cardiovascular and metabolic disease. Here we demonstrate that adipose sphingolipid metabolism is altered in genetically obese (ob/ob) mice. Expression of enzymes involved in ceramide generation (neutral sphingomyelinase [NSMase], acid sphingomyelinase [ASMase], and serine-palmitoyl-transferase [SPT]) and ceramide hydrolysis (ceramidase) are elevated in obese adipose tissues. Our data also suggest that hyperinsulinemia and elevated tumor necrosis factor (TNF)-alpha associated with obesity may contribute to the observed increase in adipose NSMase, ASMase, and SPT mRNA in this murine model of obesity. Liquid chromatography/mass spectroscopy revealed a decrease in total adipose sphingomyelin and ceramide levels but an increase in sphingosine in ob/ob mice compared with lean mice. In contrast to the adipose tissue, plasma levels of total sphingomyelin, ceramide, sphingosine, and sphingosine 1-phosphate (S1P) were elevated in ob/ob mice. In cultured adipocytes, ceramide, sphingosine, and S1P induced gene expression of plasminogen activator inhibitor-1, TNF-alpha, monocyte chemoattractant protein-1, interleukin-6, and keratinocyte-derived chemokine. Collectively, our results identify a novel role for sphingolipids in contributing to the prothrombotic and proinflammatory phenotype of the obese adipose tissue currently believed to play a major role in the pathogenesis of obesity-mediated cardiovascular and metabolic disease.
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Affiliation(s)
- Fahumiya Samad
- Division of Vascular Biology, La Jolla Institute for Molecular Medicine, San Diego, CA 92121, USA.
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48
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Yeung MY. Postnatal growth, neurodevelopment and altered adiposity after preterm birth--from a clinical nutrition perspective. Acta Paediatr 2006; 95:909-17. [PMID: 16882561 DOI: 10.1080/08035250600724507] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
UNLABELLED Evidence reveals a dilemma that under-nutrition and growth retardation during brain growth are associated with neurodevelopmental deficits, and nutritional supplement resulting in catch-up growth and relative visceral adiposity leads to metabolic/cardiovascular morbidities. Hyperinsulinaemia secondary to insulin resistance appears to play a central role in the development of visceral adiposity through its action on adipocyte beta3-adrenoceptor. CONCLUSION Optimal nutritional management to minimize hyperinsulinaemia and insulin resistance may potentially improve neurodevelopment and facilitate catch-up growth with normal body composition.
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Affiliation(s)
- Melinda Y Yeung
- Department of Pharmacy, The Children's Hospital at Westmead, New South Wales, Australia.
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Tiffin N, Adie E, Turner F, Brunner HG, van Driel MA, Oti M, Lopez-Bigas N, Ouzounis C, Perez-Iratxeta C, Andrade-Navarro MA, Adeyemo A, Patti ME, Semple CAM, Hide W. Computational disease gene identification: a concert of methods prioritizes type 2 diabetes and obesity candidate genes. Nucleic Acids Res 2006; 34:3067-81. [PMID: 16757574 PMCID: PMC1475747 DOI: 10.1093/nar/gkl381] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Genome-wide experimental methods to identify disease genes, such as linkage analysis and association studies, generate increasingly large candidate gene sets for which comprehensive empirical analysis is impractical. Computational methods employ data from a variety of sources to identify the most likely candidate disease genes from these gene sets. Here, we review seven independent computational disease gene prioritization methods, and then apply them in concert to the analysis of 9556 positional candidate genes for type 2 diabetes (T2D) and the related trait obesity. We generate and analyse a list of nine primary candidate genes for T2D genes and five for obesity. Two genes, LPL and BCKDHA, are common to these two sets. We also present a set of secondary candidates for T2D (94 genes) and for obesity (116 genes) with 58 genes in common to both diseases.
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Affiliation(s)
- Nicki Tiffin
- South African National Bioinformatics Institute, University of the Western Cape, Bellville, 7535, South Africa.
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Buggs C, Weinberg F, Kim E, Wolfe A, Radovick S, Wondisford F. Insulin augments GnRH-stimulated LHbeta gene expression by Egr-1. Mol Cell Endocrinol 2006; 249:99-106. [PMID: 16530935 PMCID: PMC3464308 DOI: 10.1016/j.mce.2006.02.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 02/01/2006] [Accepted: 02/01/2006] [Indexed: 11/29/2022]
Abstract
Previous studies have shown that insulin augments GnRH-stimulated LH synthesis and release from primary gonadotrophs. In this study, regulation of LHbeta gene expression by GnRH and insulin was examined in LbetaT2 cells. Endogenous LHbeta mRNA is stimulated 2.4-fold by insulin alone, 2.6-fold by GnRH alone, and 4.7-fold by insulin together with GnRH. This effect of insulin, like GnRH, mapped to sequences -140 to +1 in the mouse LHbeta gene. Insulin together with GnRH stimulates activity of an LHbeta-reporter gene 7.1-fold; whereas, GnRH alone or insulin alone stimulates the reporter activity 2.8- and 3.1-fold, respectively. Blocking the binding of Egr-1 to sequences -51 to -42 in the LHbeta gene inhibits effects of insulin and GnRH. Insulin together with GnRH increases Egr-1 mRNA levels and total Egr-1 binding to LHbeta DNA. These findings indicate that insulin may impact regulation of the reproductive axis at the level of the pituitary.
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Affiliation(s)
- Colleen Buggs
- Department of Pediatrics, Section of Pediatric Endocrinology, University of Chicago Children's Hospital, Chicago, IL 60637, USA.
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