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Cornell S. Continual evolution of type 2 diabetes: an update on pathophysiology and emerging treatment options. Ther Clin Risk Manag 2015; 11:621-32. [PMID: 25931824 PMCID: PMC4404882 DOI: 10.2147/tcrm.s67387] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Diabetes is a complex and progressive disease that has a major societal and economic impact. The most common form of diabetes, type 2 diabetes mellitus (T2DM), is a multifactorial disease, the pathophysiology of which involves not only the pancreas but also the liver, skeletal muscle, adipose tissue, gastrointestinal tract, brain, and kidney. Novel therapies with mechanisms of action that are different from most existing drugs are emerging. One such class consists of compounds that inhibit renal sodium-glucose cotransporter 2, which is responsible for the bulk of glucose reabsorption by the kidneys. This new class of compounds improves glycemic control independently of insulin and promotes weight reduction, providing an additional tool to treat patients with T2DM. This review discusses the underlying pathophysiology of T2DM, clinical guidelines, and available and emerging treatment options, with particular emphasis on sodium-glucose cotransporter 2 inhibitors.
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Affiliation(s)
- Susan Cornell
- Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, USA
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252
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Nutrition-dependent changes of mouse adipose tissue compositions monitored by NMR, MS, and chromatographic methods. Anal Bioanal Chem 2015; 407:5113-23. [DOI: 10.1007/s00216-015-8551-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 01/26/2015] [Accepted: 02/09/2015] [Indexed: 02/07/2023]
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253
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Kim EY, Kim WK, Oh KJ, Han BS, Lee SC, Bae KH. Recent advances in proteomic studies of adipose tissues and adipocytes. Int J Mol Sci 2015; 16:4581-99. [PMID: 25734986 PMCID: PMC4394436 DOI: 10.3390/ijms16034581] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 12/29/2014] [Accepted: 02/16/2015] [Indexed: 12/27/2022] Open
Abstract
Obesity is a chronic disease that is associated with significantly increased levels of risk of a number of metabolic disorders. Despite these enhanced health risks, the worldwide prevalence of obesity has increased dramatically over the past few decades. Obesity is caused by the accumulation of an abnormal amount of body fat in adipose tissue, which is composed mostly of adipocytes. Thus, a deeper understanding of the regulation mechanism of adipose tissue and/or adipocytes can provide a clue for overcoming obesity-related metabolic diseases. In this review, we describe recent advances in the study of adipose tissue and/or adipocytes, focusing on proteomic approaches. In addition, we suggest future research directions for proteomic studies which may lead to novel treatments of obesity and obesity-related diseases.
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Affiliation(s)
- Eun Young Kim
- Functional Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
| | - Won Kon Kim
- Functional Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
- Department of Functional Genomics, University of Science and Technology of Korea, Daejeon 305-806, Korea.
| | - Kyoung-Jin Oh
- Functional Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
| | - Baek Soo Han
- Functional Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
- Department of Functional Genomics, University of Science and Technology of Korea, Daejeon 305-806, Korea.
| | - Sang Chul Lee
- Functional Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
- Department of Functional Genomics, University of Science and Technology of Korea, Daejeon 305-806, Korea.
| | - Kwang-Hee Bae
- Functional Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
- Department of Functional Genomics, University of Science and Technology of Korea, Daejeon 305-806, Korea.
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254
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Kucuk Baloglu F, Garip S, Heise S, Brockmann G, Severcan F. FTIR imaging of structural changes in visceral and subcutaneous adiposity and brown to white adipocyte transdifferentiation. Analyst 2015; 140:2205-2214. [DOI: 10.1039/c4an02008a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
FTIR microspectroscopy coupled with UCP1 immunohistological staining enables the detection of obesity-related molecular alterations and transdifferentiations in visceral and subcutaneous adipose tissues in spontaneously obese mice lines.
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Affiliation(s)
- Fatma Kucuk Baloglu
- Department of Biological Sciences
- Middle East Technical University
- Ankara
- Turkey
| | - Sebnem Garip
- Department of Medical Biochemistry
- Faculty of Medicine
- Istanbul Kemerburgaz University
- Istanbul
- Turkey
| | - Sebastian Heise
- Department of Breeding Biology and Molecular Genetics
- Humboldt Universitatzu Berlin
- Berlin
- Germany
| | - Gudrun Brockmann
- Department of Breeding Biology and Molecular Genetics
- Humboldt Universitatzu Berlin
- Berlin
- Germany
| | - Feride Severcan
- Department of Biological Sciences
- Middle East Technical University
- Ankara
- Turkey
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255
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Hoene M, Li J, Häring HU, Weigert C, Xu G, Lehmann R. The lipid profile of brown adipose tissue is sex-specific in mice. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1842:1563-70. [PMID: 25128765 DOI: 10.1016/j.bbalip.2014.08.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/31/2014] [Accepted: 08/05/2014] [Indexed: 01/07/2023]
Abstract
Brown adipose tissue (BAT) is a thermogenic organ with a vital function in small mammals and potential as metabolic drug target in humans. By using high-resolution LC-tandem-mass spectrometry, we quantified 329 lipid species from 17 (sub)classes and identified the fatty acid composition of all phospholipids from BAT and subcutaneous and gonadal white adipose tissue (WAT) from female and male mice. Phospholipids and free fatty acids were higher in BAT, while DAG and TAG levels were higher in WAT. A set of phospholipids dominated by the residue docosahexaenoic acid, which influences membrane fluidity, showed the highest specificity for BAT. We additionally detected major sex-specific differences between the BAT lipid profiles, while samples from the different WAT depots were comparatively similar. Female BAT contained less triacylglycerol and more phospholipids rich in arachidonic and stearic acid whereas another set of fatty acid residues that included linoleic and palmitic acid prevailed in males. These differences in phospholipid fatty acid composition could greatly affect mitochondrial membranes and other cellular organelles and thereby regulate the function of BAT in a sex-specific manner.
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Affiliation(s)
- Miriam Hoene
- Division of Clinical Chemistry and Pathobiochemistry, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany.
| | - Jia Li
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Hans-Ulrich Häring
- Division of Clinical Chemistry and Pathobiochemistry, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD), Tübingen, Germany.
| | - Cora Weigert
- Division of Clinical Chemistry and Pathobiochemistry, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD), Tübingen, Germany.
| | - Guowang Xu
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Rainer Lehmann
- Division of Clinical Chemistry and Pathobiochemistry, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD), Tübingen, Germany.
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256
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Svensson PA, Lindberg K, Hoffmann JM, Taube M, Pereira MJ, Mohsen-Kanson T, Hafner AL, Rizell M, Palming J, Dani C, Svensson MK. Characterization of brown adipose tissue in the human perirenal depot. Obesity (Silver Spring) 2014; 22:1830-7. [PMID: 24753268 DOI: 10.1002/oby.20765] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 04/03/2014] [Accepted: 04/04/2014] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To characterize brown adipose tissue (BAT) in the human perirenal adipose tissue depot. METHOD Perirenal adipose tissue biopsies were obtained from 55 healthy kidney donors. Expression analysis was performed using microarray, real-time PCR, immunoblotting and immunohistochemistry. Additional studies using human stem cells were performed. RESULTS UCP1 gene expression analysis revealed a large intra-individual variation in the perirenal adipose tissue biopsies. Both multi- and unilocular UCP1-positive adipocytes were detected in several of the adipose tissue samples analyzed by immunohistochemical staining. Microarray analysis identified 54 genes that were overexpressed in UCP1-positive perirenal adipose tissue. Real-time PCR analysis of BAT candidate genes revealed a set of genes that were highly correlated to UCP1 and a set of three transcription factor genes (PRDM16, PGC1α, and RXRγ) that were highly correlated to each other. RXRγ displayed nuclear immunoreactivity in brown adipocytes and an increased gene expression during brown adipogenesis in human stem cells. CONCLUSION Our data provides the first molecular characterization of BAT in the perirenal adipose tissue depot. Furthermore, it highlights the transcription factor RXRγ as a new player in BAT development.
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Affiliation(s)
- Per-Arne Svensson
- Department of Molecular and Clinical Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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257
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Craft CS, Pietka TA, Schappe T, Coleman T, Combs MD, Klein S, Abumrad NA, Mecham RP. The extracellular matrix protein MAGP1 supports thermogenesis and protects against obesity and diabetes through regulation of TGF-β. Diabetes 2014; 63:1920-32. [PMID: 24458361 PMCID: PMC4030109 DOI: 10.2337/db13-1604] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Microfibril-associated glycoprotein 1 (MAGP1) is a component of extracellular matrix microfibrils. Here we show that MAGP1 expression is significantly altered in obese humans, and inactivation of the MAGP1 gene (Mfap2(-/-)) in mice results in adipocyte hypertrophy and predisposition to metabolic dysfunction. Impaired thermoregulation was evident in Mfap2(-/-) mice prior to changes in adiposity, suggesting a causative role for MAGP1 in the increased adiposity and predisposition to diabetes. By 5 weeks of age, Mfap2(-/-) mice were maladaptive to cold challenge, uncoupling protein-1 expression was attenuated in the brown adipose tissue, and there was reduced browning of the subcutaneous white adipose tissue. Levels of transforming growth factor-β (TGF-β) activity were elevated in Mfap2(-/-) adipose tissue, and the treatment of Mfap2(-/-) mice with a TGF-β-neutralizing antibody improved their body temperature and prevented the increased adiposity phenotype. Together, these findings indicate that the regulation of TGF-β by MAGP1 is protective against the effects of metabolic stress, and its absence predisposes individuals to metabolic dysfunction.
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Affiliation(s)
- Clarissa S Craft
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO
| | - Terri A Pietka
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Timothy Schappe
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Trey Coleman
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, MO
| | - Michelle D Combs
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO
| | - Samuel Klein
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MODepartment of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Nada A Abumrad
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MODepartment of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Robert P Mecham
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO
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258
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Sugimoto S, Nakajima H, Kodo K, Mori J, Matsuo K, Kosaka K, Aoi W, Yoshimoto K, Ikegaya H, Hosoi H. Miglitol increases energy expenditure by upregulating uncoupling protein 1 of brown adipose tissue and reduces obesity in dietary-induced obese mice. Nutr Metab (Lond) 2014; 11:14. [PMID: 24669882 PMCID: PMC3986880 DOI: 10.1186/1743-7075-11-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/08/2014] [Indexed: 11/27/2022] Open
Abstract
Background Miglitol is an oral anti-diabetic drug that acts by inhibiting carbohydrate absorption in the small intestine. Recent studies have shown that miglitol reduces obesity in humans and rodents. However, its mechanisms have remained unclear. The purpose of this study was to determine whether miglitol generates heat by activating uncoupling protein 1 (UCP1), an enzyme involved in thermogenesis, in brown adipose tissue (BAT) in mice. Methods Four-week-old male C57BL/6 J mice were fed a high-fat diet alone (HF) or a high fat diet plus miglitol (HFM). Oxygen consumption (VO2) was used to estimate metabolic rate. A thermal imaging camera was used to quantify heat generation from interscapular brown adipose tissue. We analyzed the protein and gene expressions of UCP1 and the expressions of four proteins related to β3-adrenergic signaling in the pathway activating UCP1 (protein kinase A (PKA), hormone-sensitive lipase (HSL), p38 α mitogen-activated protein kinase (p38αMAPK) and peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α)). Results At 8 weeks, body weight, epididymal and subcutaneous white adipose tissue and the HOMA-R value of the HFM mice were significantly less than those of the HF mice. Food intake was not different between the HF and HFM mice. VO2 and BAT temperature were significantly higher in the HFM mice. Miglitol significantly enhanced the gene and protein expressions of UCP1 and the expressions of proteins related to β3-adrenergic signaling. Conclusions Miglitol’s anti-obesity effect was attributed to increased energy expenditure by upregulating UCP1 in BAT (i.e., by thermogenesis) and to enhancement of β3-adrenergic signaling in BAT.
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Affiliation(s)
| | - Hisakazu Nakajima
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465-Kajiicho, Hirokoji-Kawaramachi, Kamigyo-ku, Kyoto 602-8566, Japan.
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259
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Andrade JMO, Frade ACM, Guimarães JB, Freitas KM, Lopes MTP, Guimarães ALS, de Paula AMB, Coimbra CC, Santos SHS. Resveratrol increases brown adipose tissue thermogenesis markers by increasing SIRT1 and energy expenditure and decreasing fat accumulation in adipose tissue of mice fed a standard diet. Eur J Nutr 2014; 53:1503-10. [DOI: 10.1007/s00394-014-0655-6] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Accepted: 01/13/2014] [Indexed: 11/29/2022]
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260
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Expression of "brown-in-white" adipocyte biomarkers shows gender differences and the influence of early dietary exposure. GENES AND NUTRITION 2013; 9:372. [PMID: 24292948 DOI: 10.1007/s12263-013-0372-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 11/08/2013] [Indexed: 01/01/2023]
Abstract
Induction of brown-like adipocytes (brite) in white adipose tissues may allow the conversion of lipid storage cells in fat-burning cells. Little is known concerning browning potential in males compared with females. In this study, we aimed to analyse whether gender differences were present in gene expression of "brite" markers as well as the impact of dietary manipulation at both early stages and adulthood in rats. We have determined the expression of brite markers and genes associated with lipid and energy metabolism in inguinal adipose tissue in adult male and female rats. We have analysed the impact of high-fat (HF) diet in adult life and of early leucine supplementation (2 %) during lactation. Results show that although both genders have the potential to induce brite genes in inguinal adipose tissue, males expressed higher levels (CIDEA, HOXC9 and SHOX2), which would imply a higher browning capacity in comparison with females. Minor impact of HF diet in adult life was observed in most of the genes studied. Interestingly, results showed that early Leu was able to compromise the metabolic fate of white and brite adipocytes later in adult life. Leucine supplementation programmed higher expression of cell death-inducing DFFA-like effector, accompanied with induction of sterol regulatory element binding transcription 1c factor and lower UPC2 expression, particularly in females. In addition, Leucine supplementation was associated with higher expression of leptin and PPARγ and decreased carnitine palmitoyl transferase in both genders. Although the exact role of these adaptations needs further comprehensive analysis, dietary Leu supplementation at early age programmed inguinal adipose tissue in a gender specific manner.
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261
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Chujo Y, Fujii N, Okita N, Konishi T, Narita T, Yamada A, Haruyama Y, Tashiro K, Chiba T, Shimokawa I, Higami Y. Caloric restriction-associated remodeling of rat white adipose tissue: effects on the growth hormone/insulin-like growth factor-1 axis, sterol regulatory element binding protein-1, and macrophage infiltration. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1143-1156. [PMID: 22645024 PMCID: PMC3705091 DOI: 10.1007/s11357-012-9439-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 05/16/2012] [Indexed: 06/01/2023]
Abstract
The role of the growth hormone (GH)-insulin-like growth factor (IGF)-1 axis in the lifelong caloric restriction (CR)-associated remodeling of white adipose tissue (WAT), adipocyte size, and gene expression profiles was explored in this study. We analyzed the WAT morphology of 6-7-month-old wild-type Wistar rats fed ad libitum (WdAL) or subjected to CR (WdCR), and of heterozygous transgenic dwarf rats bearing an anti-sense GH transgene fed ad libitum (TgAL) or subjected to CR (TgCR). Although less effective in TgAL, the adipocyte size was significantly reduced in WdCR compared with WdAL. This CR effect was blunted in Tg rats. We also used high-density oligonucleotide microarrays to examine the gene expression profile of WAT of WdAL, WdCR, and TgAL rats. The gene expression profile of WdCR, but not TgAL, differed greatly from that of WdAL. The gene clusters with the largest changes induced by CR but not by Tg were genes involved in lipid biosynthesis and inflammation, particularly sterol regulatory element binding proteins (SREBPs)-regulated and macrophage-related genes, respectively. Real-time reverse-transcription polymerase chain reaction analysis confirmed that the expression of SREBP-1 and its downstream targets was upregulated, whereas the macrophage-related genes were downregulated in WdCR, but not in TgAL. In addition, CR affected the gene expression profile of Tg rats similarly to wild-type rats. Our findings suggest that CR-associated remodeling of WAT, which involves SREBP-1-mediated transcriptional activation and suppression of macrophage infiltration, is regulated in a GH-IGF-1-independent manner.
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Affiliation(s)
- Yoshikazu Chujo
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Namiki Fujii
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Naoyuki Okita
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Tomokazu Konishi
- />Molecular Genetics Group, Akita Prefectural University, Akita, Japan
| | - Takumi Narita
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Atsushi Yamada
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Yushi Haruyama
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Kosuke Tashiro
- />Graduate School of Bioresource and Bioenvironmental Sciences, Molecular Gene Technics, Kyushu University, Fukuoka, Japan
| | - Takuya Chiba
- />Department of Investigative Pathology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Isao Shimokawa
- />Department of Investigative Pathology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yoshikazu Higami
- />Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
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262
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Westley RL, May FEB. A twenty-first century cancer epidemic caused by obesity: the involvement of insulin, diabetes, and insulin-like growth factors. Int J Endocrinol 2013; 2013:632461. [PMID: 23983688 PMCID: PMC3747439 DOI: 10.1155/2013/632461] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 03/25/2013] [Indexed: 02/08/2023] Open
Abstract
Obesity has reached epidemic proportions in the developed world. The progression from obesity to diabetes mellitus type 2, via metabolic syndrome, is recognised, and the significant associated increase in the risk of major human cancers acknowledged. We review the molecular basis of the involvement of morbidly high concentrations of endogenous or therapeutic insulin and of insulin-like growth factors in the progression from obesity to diabetes and finally to cancer. Epidemiological and biochemical studies establish the role of insulin and hyperinsulinaemia in cancer risk and progression. Insulin-like growth factors, IGF-1 and IGF-2, secreted by visceral or mammary adipose tissue have significant paracrine and endocrine effects. These effects can be exacerbated by increased steroid hormone production. Structural studies elucidate how each of the three ligands, insulin, IGF-1, and IGF-2, interacts differently with isoforms A and B of the insulin receptor and with type I IGF receptor and explain how these protagonists contribute to diabetes-associated cancer. The above should inform appropriate treatment of cancers that arise in obese individuals and in those with diabetes mellitus type 2. Novel drugs that target the insulin and insulin-like growth factor signal transduction pathways are in clinical trial and should be effective if appropriate biomarker-informed patient stratification is implemented.
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Affiliation(s)
- Rosalyne L. Westley
- Northern Institute for Cancer Research, Faculty of Medical Sciences, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Felicity E. B. May
- Northern Institute for Cancer Research, Faculty of Medical Sciences, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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263
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Carter S, Caron A, Richard D, Picard F. Role of leptin resistance in the development of obesity in older patients. Clin Interv Aging 2013; 8:829-44. [PMID: 23869170 PMCID: PMC3706252 DOI: 10.2147/cia.s36367] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Obesity is a global epidemic associated with aging-like cellular processes; in both aging and obesity, resistance to hormones such as insulin and leptin can be observed. Leptin is a circulating hormone/cytokine with central and peripheral effects that is released mainly by subcutaneous white adipose tissue. Centrally, leptin controls food intake, energy expenditure, and fat distribution, whereas it controls (among several others) insulin sensitivity, free fatty acids (FFAs) oxidation, and lipolysis in the periphery. Aging is associated with important changes in both the distribution and the composition of adipose tissue. Fat is redistributed from the subcutaneous to the visceral depot and increased inflammation participates in adipocyte dysfunction. This redistribution of adipose tissue in favor of visceral fat influences negatively both longevity and healthy aging as shown in numerous animal models. These modifications observed during aging are also associated with leptin resistance. This resistance blunts normal central and peripheral functions of leptin, which leads to a decrease in neuroendocrine function and insulin sensitivity, an imbalance in energy regulation, and disturbances in lipid metabolism. Here, we review how age-related leptin resistance triggers metabolic disturbances and affects the longevity of obese patients. Furthermore, we discuss the potential impacts of leptin resistance on the decline of brown adipose tissue thermogenesis observed in elderly individuals.
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Affiliation(s)
- Sophie Carter
- Faculty of Pharmacy, Department of Anatomy and Physiology, Université Laval, Québec, QC, Canada
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264
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Ren G, Beech C, Smas CM. The immunoglobulin superfamily protein differentiation of embryonic stem cells 1 (dies1) has a regulatory role in preadipocyte to adipocyte conversion. PLoS One 2013; 8:e65531. [PMID: 23799023 PMCID: PMC3684596 DOI: 10.1371/journal.pone.0065531] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 05/01/2013] [Indexed: 11/19/2022] Open
Abstract
Differentiation of Embryonic Stem Cells 1 (Dies1) was recently identified as a novel type I immunoglobulin (IgG) domain-containing plasma membrane protein important for effective differentiation of a murine pluripotent embryonic stem cell line. In this setting, Dies1 enhances bone morphogenetic protein 4 (BMP4) signaling. Here we show Dies1 transcript expression is induced ∼225-fold during in vitro adipogenesis of 3T3-L1 murine preadipocytes. Immunocytochemical imaging using ectopic expression of Flag-tagged Dies1 in 3T3-L1 adipocytes revealed localization to the adipocyte plasma membrane. Modulation of adipocyte phenotype with with tumor necrosis factor-α (TNFα) treatment or by siRNA knockdown of the master pro-adipogenic transcription factor peroxisome proliferator activated receptor gamma (PPARγ) resulted in a 90% and 60% reduction of Dies1 transcript levels, respectively. Moreover, siRNA-mediated Dies1 knockdown in 3T3-L1 preadipocytes inhibited adipogenic conversion. Such cultures had a 35% decrease in lipid content and a 45%–65% reduction in expression of key adipocyte transcripts, including that for PPARγ. The standard protocol for full in vitro adipogenic conversion of committed preadipocytes, such as 3T3-L1, does not include BMP4 treatment. Thus we posit the positive role of Dies1 in adipogenesis, unlike that for Dies1 in differentiation of embryonic stem cells, does not include its pro-BMP4 effects. In support of this idea, 3T3-L1 adipocytes knocked down for Dies1 did not evidence decreased phospho-Smad1 levels upon BMP4 exposure. qPCR analysis of Dies1 transcript in multiple murine and human tissues reveals high enrichment in white adipose tissue (WAT). Interestingly, we observed a 10-fold induction of Dies1 transcript in WAT of fasted vs. fed mice, suggesting a role for Dies1 in nutritional response of mature fat cells in vivo. Together our data identify Dies1 as a new differentiation-dependent adipocyte plasma membrane protein whose expression is required for effective adipogenesis and that may also play a role in regard to nutritional status in WAT.
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Affiliation(s)
- Gang Ren
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio, United States of America
| | - Cameron Beech
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio, United States of America
| | - Cynthia M. Smas
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio, United States of America
- Center for Diabetes and Endocrine Research, University of Toledo College of Medicine, Toledo, Ohio, United States of America
- * E-mail:
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265
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Bethel M, Chitteti BR, Srour EF, Kacena MA. The changing balance between osteoblastogenesis and adipogenesis in aging and its impact on hematopoiesis. Curr Osteoporos Rep 2013; 11:99-106. [PMID: 23423562 PMCID: PMC3643998 DOI: 10.1007/s11914-013-0135-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Osteoblasts (OBs) and adipocytes (APs) share a common mesenchymal ancestor. It is now clear that mesenchymal stem cell (MSC) maturation along the OB lineage comes at the expense of adipogenesis and vice versa. During aging, this balance increasingly favors the formation of APs. Hematopoiesis also slowly declines during the aging process. The role of OB lineage cells in hematopoiesis has been studied, but less is known about how APs regulate hematopoiesis. A few studies have demonstrated a negative relationship between APs and hematopoiesis; however, there is also evidence that brown adipose tissue (BAT) may promote hematopoiesis. This review will examine the current knowledge of how adipogenesis and osteogenesis change with aging and the implications of this changing environment on hematopoeisis.
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Affiliation(s)
- Monique Bethel
- Postdoctoral Fellow, Department of Orthopaedic Surgery, Indiana University School of Medicine, 1120 South Drive, FH 115, Indianapolis, IN 46202, 317-278-2804 (phone), 317-278-9568 (fax),
| | - Brahmananda R. Chitteti
- Postdoctoral Fellow, Department of Medicine. Indiana University School of Medicine, 980 W. Walnut Street, R3-C356, Indianapolis, IN 46202, 317-274-0352 (phone), 317-274-0396 (fax),
| | - Edward F. Srour
- Robert J. and Annie S. Rohn Professor of Leukemia Research, Departments of Medicine, Pediatrics, Microbiology and Immunology. Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, 980 W. Walnut Street, R3-C312, Indianapolis, IN 46202, 317-274-0343 (phone), 317-274-0396 (fax),
| | - Melissa A. Kacena
- Assistant Professor, Department of Orthopaedic Surgery, Indiana University School of Medicine, 1120 South Drive, FH 115H, Indianapolis, IN 46202, 317-2783482 (phone), 317-278-9568 (Fax),
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266
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Renes J, Mariman E. Application of proteomics technology in adipocyte biology. MOLECULAR BIOSYSTEMS 2013; 9:1076-91. [PMID: 23629546 DOI: 10.1039/c3mb25596d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Obesity and its associated complications have reached epidemic proportions in Western-type societies. Concomitantly, the obesity incidence in developing countries is increasing. One hallmark of obesity is the differentiation of pre-adipocytes into mature triglyceride-loaded adipocytes present in subcutaneous and visceral adipose tissue depots. This may ultimately lead to dysfunctional adipose tissue together with detrimental changes in the profiles of (pre-)adipocyte-secreted proteins, known as adipokines. Obesity-induced alterations in adipokine profiles contribute to the development of obesity-associated disorders. Consequently, the interest in the molecular events responsible for adipose tissue modifications during weight gain and weight loss as well as in the aetiology of obesity-associated disorders is growing. Molecular mechanisms involved in pre-adipocyte differentiation and alterations in adipokine profiles have been examined at the gene and protein level by high-throughput technologies. Independent proteomics studies have contributed significantly to further insight into adipocyte biology, particularly with respect to adipokine profiling. In this review novel findings obtained with adipo-proteomics studies are highlighted and the relevance of proteomics technologies to further understand molecular aspects of adipocyte biology is discussed.
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Affiliation(s)
- Johan Renes
- Department of Human Biology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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267
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Coelho M, Oliveira T, Fernandes R. Biochemistry of adipose tissue: an endocrine organ. Arch Med Sci 2013; 9:191-200. [PMID: 23671428 PMCID: PMC3648822 DOI: 10.5114/aoms.2013.33181] [Citation(s) in RCA: 698] [Impact Index Per Article: 63.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 07/02/2012] [Accepted: 07/04/2012] [Indexed: 02/06/2023] Open
Abstract
Adipose tissue is no longer considered to be an inert tissue that stores fat. This tissue is capable of expanding to accommodate increased lipids through hypertrophy of existing adipocytes and by initiating differentiation of pre-adipocytes. Adipose tissue metabolism exerts an impact on whole-body metabolism. As an endocrine organ, adipose tissue is responsible for the synthesis and secretion of several hormones. These are active in a range of processes, such as control of nutritional intake (leptin, angiotensin), control of sensitivity to insulin and inflammatory process mediators (tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), resistin, visfatin, adiponectin, among others) and pathways (plasminogen activator inhibitor 1 (PAI-1) and acylation stimulating protein (ASP) for example). This paper reviews some of the biochemical and metabolic aspects of adipose tissue and its relationship to inflammatory disease and insulin resistance.
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Affiliation(s)
- Marisa Coelho
- Ciências Químicas e das Biomoléculas e Unidade de Mecanismos Moleculares da Doença do Centro de Investigação em Saúde e Ambiente, Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Portugal ; Centro de Farmacologia e Biopatologia Química (U38-FCT), Faculdade de Medicina da Universidade do Porto, Portugal
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268
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Hegde V, Dhurandhar N. Microbes and obesity—interrelationship between infection, adipose tissue and the immune system. Clin Microbiol Infect 2013; 19:314-20. [DOI: 10.1111/1469-0691.12157] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 01/07/2013] [Indexed: 01/16/2023]
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269
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Abstract
Breast reconstruction is a type of surgery for women who have had a mastectomy, and involves using autologous tissue or prosthetic material to construct a natural-looking breast. Adipose tissue is the major contributor to the volume of the breast, whereas epithelial cells comprise the functional unit of the mammary gland. Adipose-derived stem cells (ASCs) can differentiate into both adipocytes and epithelial cells and can be acquired from autologous sources. ASCs are therefore an attractive candidate for clinical applications to repair or regenerate the breast. Here we review the current state of adipose tissue engineering methods, including the biomaterials used for adipose tissue engineering and the application of these techniques for mammary epithelial tissue engineering. Adipose tissue engineering combined with microfabrication approaches to engineer the epithelium represents a promising avenue to replicate the native structure of the breast.
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Affiliation(s)
- Wenting Zhu
- Department of Chemical and Biological Engineering; Princeton University; Princeton, NJ USA
| | - Celeste M Nelson
- Department of Chemical and Biological Engineering; Princeton University; Princeton, NJ USA; Department of Molecular Biology; Princeton University; Princeton, NJ USA
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270
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Zhang X, Heckmann BL, Liu J. Studying lipolysis in adipocytes by combining siRNA knockdown and adenovirus-mediated overexpression approaches. Methods Cell Biol 2013; 116:83-105. [PMID: 24099289 DOI: 10.1016/b978-0-12-408051-5.00006-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
3T3-L1 adipocytes are widely used as a model system for studying hormone-stimulated lipolysis. However, these cells were limited in their utility for gain- and loss-of-function studies due to the low efficiency of their transfection with plasmid DNA or small interfering RNA (siRNA) oligos. In this chapter, we provide a review of two methods established for manipulation of protein expression in differentiated mature adipocytes. The use of electroporation allows a high-efficiency delivery of siRNA oligos and subsequent knockdown of specific gene expression. A centrifugation-assisted infection with recombinant adenovirus, on the other hand, enables robust overexpression of ectopic proteins. Most importantly, by combining siRNA electroporation with adenovirus infection, simultaneous manipulation of levels of two different proteins can be achieved in differentiated adipocytes. Through subsequent analyses of lipase activity in cell extracts and fatty acid or glycerol release from living cells, mutual interdependence between the two proteins in the context of basal and hormone-stimulated adipocyte lipolysis can be evaluated.
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Affiliation(s)
- Xiaodong Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic in Arizona, Scottsdale, Arizona, USA; Metabolic HEALth Program, Mayo Clinic in Arizona, Scottsdale, Arizona, USA
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271
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Shibasaki M, Okazaki K, Inoue Y. Aging and thermoregulation. JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2013. [DOI: 10.7600/jpfsm.2.37] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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272
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In utero programming of later adiposity: the role of fetal growth restriction. J Pregnancy 2012; 2012:134758. [PMID: 23251802 PMCID: PMC3518064 DOI: 10.1155/2012/134758] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 10/17/2012] [Indexed: 12/19/2022] Open
Abstract
Intrauterine growth restriction (IUGR) is strongly associated with obesity in adult life. The mechanisms contributing to the onset of IUGR-associated adult obesity have been studied in animal models and humans, where changes in fetal adipose tissue development, hormone levels and epigenome have been identified as principal areas of alteration leading to later life obesity. Following an adverse in utero development, IUGR fetuses display increased lipogenic and adipogenic capacity in adipocytes, hypoleptinemia, altered glucocorticoid signalling, and chromatin remodelling, which subsequently all contribute to an increased later life obesity risk. Data suggest that many of these changes result from an enhanced activity of the adipose master transcription factor regulator, peroxisome proliferator-activated receptor-γ (PPARγ) and its coregulators, increased lipogenic fatty acid synthase (FAS) expression and activity, and upregulation of glycolysis in fetal adipose tissue. Increased expression of fetal hypothalamic neuropeptide Y (NPY), altered hypothalamic leptin receptor expression and partitioning, reduced adipose noradrenergic sympathetic innervations, enhanced adipose glucocorticoid action, and modifications in methylation status in the promoter of hepatic and adipose adipogenic and lipogenic genes in the fetus also contribute to obesity following IUGR. Therefore, interventions that inhibit these fetal developmental changes will be beneficial for modulation of adult body fat accumulation.
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273
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Lima-Martínez MM, Blandenier C, Iacobellis G. [Epicardial adipose tissue: more than a simple fat deposit?]. ACTA ACUST UNITED AC 2012; 60:320-8. [PMID: 23117053 DOI: 10.1016/j.endonu.2012.08.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 08/22/2012] [Accepted: 08/23/2012] [Indexed: 01/13/2023]
Abstract
Obesity increases the risk of development of atherosclerosis. However, this risk significantly depends on adipose tissue distribution in the body and ectopic accumulation of visceral adipose tissue (VAT). Recent evidence suggests that each visceral fat deposit is anatomically and functionally different. Due to proximity to the organ, each visceral fat deposit exerts a local modulation rather than a systemic effect. Because of its unique location and biomolecular properties, a "non-traditional" fat depot - the epicardial adipose tissue - has been considered to play a causative role in atherosclerosis. Epicardial adipose tissue may be measured with imaging techniques and is clinically related to left ventricular mass, coronary artery disease, and metabolic syndrome. Therefore, epicardial fat measurement may play a role in stratification of cardiometabolic risk and may serve as a therapeutic target.
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Affiliation(s)
- Marcos M Lima-Martínez
- Unidad de Endocrinología, Instituto Autónomo Hospital Universitario de los Andes, Mérida, Venezuela.
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274
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Leiherer A, Mündlein A, Drexel H. Phytochemicals and their impact on adipose tissue inflammation and diabetes. Vascul Pharmacol 2012; 58:3-20. [PMID: 22982056 DOI: 10.1016/j.vph.2012.09.002] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 09/03/2012] [Accepted: 09/04/2012] [Indexed: 01/17/2023]
Abstract
Type 2 diabetes mellitus is an inflammatory disease and the mechanisms that underlie this disease, although still incompletely understood, take place in the adipose tissue of obese subjects. Concurrently, the prevalence of obesity caused by Western diet's excessive energy intake and the lack of exercise escalates, and is believed to be causative for the chronic inflammatory state in adipose tissue. Overnutrition itself as an overload of energy may induce the adipocytes to secrete chemokines activating and attracting immune cells to adipose tissue. But also inflammation-mediating food ingredients like saturated fatty acids are believed to directly initiate the inflammatory cascade. In addition, hypoxia in adipose tissue as a direct consequence of obesity, and its effect on gene expression in adipocytes and surrounding cells in fat tissue of obese subjects appears to play a central role in this inflammatory response too. In contrast, revisiting diet all over the world, there are also some natural food products and beverages which are associated with curative effects on human health. Several natural compounds known as spices such as curcumin, capsaicin, and gingerol, or secondary plant metabolites catechin, resveratrol, genistein, and quercetin have been reported to provide an improved health status to their consumers, especially with regard to diabetes, and therefore have been investigated for their anti-inflammatory effect. In this review, we will give an overview about these phytochemicals and their role to interfere with inflammatory cascades in adipose tissue and their potential for fighting against inflammatory diseases like diabetes as investigated in vivo.
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Affiliation(s)
- Andreas Leiherer
- Vorarlberg Institute for Vascular Investigation and Treatment, Feldkirch, Austria
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275
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Verty ANA, Lockie SH, Stefanidis A, Oldfield BJ. Anti-obesity effects of the combined administration of CB1 receptor antagonist rimonabant and melanin-concentrating hormone antagonist SNAP-94847 in diet-induced obese mice. Int J Obes (Lond) 2012; 37:279-87. [PMID: 22473329 DOI: 10.1038/ijo.2012.35] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Current anti-obesity monotherapies have proven only marginally effective and are often accompanied by adverse side effects. The cannabinoid 1 (CB1) receptor antagonist rimonabant, while effective at producing weight loss, has been discontinued from clinical use owing to increased incidence of depression. This study investigates the interaction between the cannabinoid and melanin-concentrating hormone (MCH) systems in food intake, body weight control, and mood. DESIGN Lean male C57BL/6 mice were injected i.p. with rimonabant (0.0, 0.03, 0.3 and 3.0 mg kg(-1)) or the MCH1-R antagonist SNAP-94847 (0.0, 1.0, 5.0 and 10.0 mg kg(-1)) to establish dose response parameters for each drug. Diet-induced obese (DIO) mice were given either vehicle, sub-threshold dose of rimonabant and SNAP-94847 alone or in combination. Impact on behavioral outcomes, food intake, body weight, plasma metabolites and expression of key metabolic proteins in the brown adipose tissue (BAT) and white adipose tissue (WAT) were measured. RESULTS The high doses of rimonabant and SNAP-94847 produced a reduction in food intake after 2 and 24 h. Combining sub-threshold doses of rimonabant and SNAP-94847 produced a significantly greater loss of body weight in DIO mice compared with vehicle and monotherapies. In addition, combining sub effective doses of these drugs led to a shift in markers of thermogenesis in BAT and lipid metabolism in WAT consistent with increased energy expenditure and lipolysis. Furthermore, co-administration of rimonabant and SNAP-94847 produced a transient reduction in food intake, and significantly reduced fat mass and adipocyte size. Importantly, SNAP-94847 significantly attenuated the ability of rimonabant to reduced immobility time in the forced swim test. CONCLUSION These results provide proof of principle that combination of rimonabant and a MCH1 receptor antagonist is highly effective in reducing body weight below that achieved by rimonabant and SNAP-94847 monotherapies. In addition, the combination therapy normalizes the rimonabant-induced behavioral changes seen in the forced swim test.
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Affiliation(s)
- A N A Verty
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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276
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Shimada K, Ohno Y, Okamatsu-Ogura Y, Suzuki M, Kamikawa A, Terao A, Kimura K. Neuropeptide Y activates phosphorylation of ERK and STAT3 in stromal vascular cells from brown adipose tissue, but fails to affect thermogenic function of brown adipocytes. Peptides 2012; 34:336-42. [PMID: 22374387 DOI: 10.1016/j.peptides.2012.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 02/16/2012] [Accepted: 02/16/2012] [Indexed: 12/22/2022]
Abstract
The thermogenic function of brown adipose tissue (BAT) is increased by norepinephrine (NE) released from sympathetic nerve endings, but the roles of NPY released along with NE are poorly elucidated. Here, we examined effect of NPY on basal and NE-enhanced thermogenesis in isolated brown adipocytes that express Y1 and Y5 receptor mRNA. Treatment of cells with NPY did not influence the basal and NE-enhanced rates of oxygen consumption and cAMP accumulation. Treatment with NPY also failed to induce ERK (Thr202/Tyr204) phosphorylation in the brown adipocytes. In contrast, treatment with NPY increased ERK phosphorylation in cultured stromal vascular cells from the BAT that express Y1 receptor mRNA. In the latter treatment with NPY also increased STAT3 (Ser727) phosphorylation. These results suggest that NPY mainly acts on stromal vascular cells in BAT and plays roles in the regulation of their gene transcription through ERK and STAT3 pathways, while NPY does not affect the thermogenic function of brown adipocytes.
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Affiliation(s)
- Kohei Shimada
- Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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277
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Abstract
Obesity shares with most chronic diseases the presence of an inflammatory component, which accounts for the development of metabolic disease and other associated health alterations. This inflammatory state is reflected in increased circulating levels of pro-inflammatory proteins, and it occurs not only in adults but also in adolescents and children. The chronic inflammatory response has its origin in the links existing between the adipose tissue and the immune system. Obesity, like other states of malnutrition, is known to impair the immune function, altering leucocyte counts as well as cell-mediated immune responses. In addition, evidence has arisen that an altered immune function contributes to the pathogenesis of obesity. This review attempts to briefly comment on the various plausible explanations that have been proposed for the phenomenon: (1) the obesity-associated increase in the production of leptin (pro-inflammatory) and the reduction in adiponectin (anti-inflammatory) seem to affect the activation of immune cells; (2) NEFA can induce inflammation through various mechanisms (such as modulation of adipokine production or activation of Toll-like receptors); (3) nutrient excess and adipocyte expansion trigger endoplasmic reticulum stress; and (4) hypoxia occurring in hypertrophied adipose tissue stimulates the expression of inflammatory genes and activates immune cells. Interestingly, data suggest a greater impact of visceral adipose tissue and central obesity, rather than total body fat, on the inflammatory process. In summary, there is a positive feedback loop between local inflammation in adipose tissue and altered immune response in obesity, both contributing to the development of related metabolic complications.
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278
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Belaj KJ, Eller P. The fate of fat. Gerontology 2011; 58:120-2; discussion 123-5. [PMID: 22178789 DOI: 10.1159/000331798] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 08/04/2011] [Indexed: 01/18/2023] Open
Abstract
Adipose tissue is not merely a storage depot for fat. Both brown and white adipose tissues are finely regulated endocrine organs that modulate energy balance and temperature homeostasis. In a recent issue of Gerontology, Saely and Drexel dissected the different morphology and the prime functions of brown and white adipose tissue. They impressively showed that adipose tissues are not inert deposits, but instead highly plastic tissues in close interface with guts, liver, and brain. Brown and white adipose tissues are essentially complementary organs that serve different teleological purposes. The molecular understanding of their physiological pathways opens the door to the development of a rational pharmacotherapy of obesity and associated disorders. Thus, the targeting of energy expenditure in brown adipose tissue may be an attractive alternative strategy to combat obesity. However, every intervention in cellular bioenergetics to treat obesity or cachexia will have to face principal safety considerations, as the thermodynamic implications of such interventions are largely unknown and potentially dangerous.
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Affiliation(s)
- Klara J Belaj
- Division of Angiology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
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279
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Vykoukal D, Davies MG. Vascular biology of metabolic syndrome. J Vasc Surg 2011; 54:819-31. [PMID: 21439758 PMCID: PMC3136643 DOI: 10.1016/j.jvs.2011.01.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 01/02/2011] [Accepted: 01/06/2011] [Indexed: 12/20/2022]
Abstract
The metabolic syndrome is a constellation of clinical risk factors comprising atherogenic dyslipidemia (low high-density lipoprotein and high triglycerides levels), elevated blood pressure, elevated plasma glucose, a prothrombotic state, and a proinflammatory state accompanied by an increased risk for cardiovascular disease and type 2 diabetes mellitus. The adipose tissue of obese humans contains increased numbers of macrophages, and once activated, these macrophages are responsible for the expression of most of the tissue's tumor necrosis factor (TNF)-α and interleukin (IL)-6. Chronic inflammation associated with visceral obesity induces altered lipoprotein metabolism and insulin resistance in the liver. Adipocytes secrete a variety of hormones, cytokines, growth factors, and other bioactive substances, conceptualized as adipocytokines, including plasminogen activator inhibitor 1 (PAI-1), TNF-α, leptin, and adiponectin. The dysregulation of these adipokines contributes to the pathogenesis of obesity. Adipose tissue-resident macrophages and adipocytes in the adipose tissue combined with the consequences of hyperglycemia, altered lipoproteins, and hyperinsulinemia in the vasculature and within organ microcirculation lead to dysfunctional endothelia and a proinflammatory state. Metabolic syndrome thus represents a combination of synergistic vascular pathologies that lead to an accelerated atherogenic state that compromises the ability of the patient to satisfactorily respond to humoral, cellular, and mechanical stresses.
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Affiliation(s)
- Daynene Vykoukal
- Vascular Biology and Therapeutics Program, The Methodist Hospital Research Institute, The Methodist Hospital, Houston, TX77030, USA
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