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102
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Affiliation(s)
| | - C Ronald Kahn
- Joslin Diabetes Center, Harvard Medical School, Boston, MA
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103
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Abstract
Nonalcoholic fatty liver disease (NAFLD) is a liver manifestation of metabolic syndrome. Overconsumption of high-fat diet (HFD) and increased intake of sugar-sweetened beverages are major risk factors for development of NAFLD. Today the most commonly consumed sugar is high fructose corn syrup. Hepatic lipids may be derived from dietary intake, esterification of plasma free fatty acids (FFA) or hepatic de novo lipogenesis (DNL). A central abnormality in NAFLD is enhanced DNL. Hepatic DNL is increased in individuals with NAFLD, while the contribution of dietary fat and plasma FFA to hepatic lipids is not significantly altered. The importance of DNL in NAFLD is further established in mouse studies with knockout of genes involved in this process. Dietary fructose increases levels of enzymes involved in DNL even more strongly than HFD. Several properties of fructose metabolism make it particularly lipogenic. Fructose is absorbed via portal vein and delivered to the liver in much higher concentrations as compared to other tissues. Fructose increases protein levels of all DNL enzymes during its conversion into triglycerides. Additionally, fructose supports lipogenesis in the setting of insulin resistance as fructose does not require insulin for its metabolism, and it directly stimulates SREBP1c, a major transcriptional regulator of DNL. Fructose also leads to ATP depletion and suppression of mitochondrial fatty acid oxidation, resulting in increased production of reactive oxygen species. Furthermore, fructose promotes ER stress and uric acid formation, additional insulin independent pathways leading to DNL. In summary, fructose metabolism supports DNL more strongly than HFD and hepatic DNL is a central abnormality in NAFLD. Disrupting fructose metabolism in the liver may provide a new therapeutic option for the treatment of NAFLD.
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Affiliation(s)
- Samir Softic
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, MA.,Department of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, MA
| | - David E. Cohen
- Division of Gastroenterology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School
| | - C. Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, MA
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104
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Viana-Huete V, Guillén C, García-Aguilar A, García G, Fernández S, Kahn CR, Benito M. Essential Role of IGFIR in the Onset of Male Brown Fat Thermogenic Function: Regulation of Glucose Homeostasis by Differential Organ-Specific Insulin Sensitivity. Endocrinology 2016; 157:1495-511. [PMID: 26910308 PMCID: PMC6285213 DOI: 10.1210/en.2015-1623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Brown fat is a thermogenic tissue that generates heat to maintain body temperature in cold environments and dissipate excess energy in response to overfeeding. We have addressed the role of the IGFIR in the brown fat development and function. Mice lacking IGFIR exhibited normal brown adipose tissue/body weight in knockout (KO) vs control mice. However, lack of IGFIR decreased uncoupling protein 1 expression in interscapular brown fat and beige cells in inguinal fat. More importantly, the lack of IGFIR resulted in an impaired cold acclimation. No differences in the total fat volume were found in the KO vs control mice. Epididymal fat showed larger adipocytes but with a lower number of adipocytes in KO vs control mice at age 12 months. In addition, KO mice showed a sustained moderate hyperinsulinemia and hypertriglyceridemia upon time and hepatic insulin insensitivity associated with lipid accumulation, with the outcome of a global insulin resistance. In addition, we found that the expression of uncoupling protein 3 in the skeletal muscle was decreased and its expression was increased in the heart in parallel with the expression of beta-2 adrenergic receptors. Upon nonobesogenic high-fat diet, we found a severe insulin resistance in the liver and in the skeletal muscle, but unchanged insulin sensitivity in the heart. In conclusion, our data suggest that IGFIR it is not an essential growth factor in the brown fat development in the presence of the IR and very high plasma levels of IGF-I, but it is indispensable for full brown fat functionality.
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Affiliation(s)
- Vanesa Viana-Huete
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
| | - Carlos Guillén
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
| | - Ana García-Aguilar
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
| | - Gema García
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
| | - Silvia Fernández
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
| | - C R Kahn
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
| | - Manuel Benito
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Complutense University-Madrid, Madrid 28040, Spain; Spanish Diabetes and Metabolic Research Network (V.V.-H., C.G., A.G.-A., G.G., S.F., M.B.), Institute of Health Carlos III, Madrid 28029, Spain; and Joslin Diabetes Center (C.R.K.), Harvard Medical School, Boston, MA 02215
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105
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Stoeckel LE, Arvanitakis Z, Gandy S, Small D, Kahn CR, Pascual-Leone A, Pawlyk A, Sherwin R, Smith P. Complex mechanisms linking neurocognitive dysfunction to insulin resistance and other metabolic dysfunction. F1000Res 2016; 5:353. [PMID: 27303627 PMCID: PMC4897751 DOI: 10.12688/f1000research.8300.2] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/31/2016] [Indexed: 01/12/2023] Open
Abstract
Scientific evidence has established several links between metabolic and neurocognitive dysfunction, and epidemiologic evidence has revealed an increased risk of Alzheimer’s disease and vascular dementia in patients with diabetes. In July 2015, the National Institute of Diabetes, Digestive, and Kidney Diseases gathered experts from multiple clinical and scientific disciplines, in a workshop entitled “The Intersection of Metabolic and Neurocognitive Dysfunction”, to clarify the state-of-the-science on the mechanisms linking metabolic dysfunction, and insulin resistance and diabetes in particular, to neurocognitive impairment and dementia. This perspective is intended to serve as a summary of the opinions expressed at this meeting, which focused on identifying gaps and opportunities to advance research in this emerging area with important public health relevance.
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Affiliation(s)
- Luke E Stoeckel
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Zoe Arvanitakis
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA
| | - Sam Gandy
- Icahn School of Medicine and James J. Peters VAMC, New York, NY, USA
| | - Dana Small
- Yale University School of Medicine, New Haven, CT, USA
| | - C Ronald Kahn
- Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation and Division for Cognitive Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Aaron Pawlyk
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | | | - Philip Smith
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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106
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Winnay JN, Solheim MH, Dirice E, Sakaguchi M, Noh HL, Kang HJ, Takahashi H, Chudasama KK, Kim JK, Molven A, Kahn CR, Njølstad PR. PI3-kinase mutation linked to insulin and growth factor resistance in vivo. J Clin Invest 2016; 126:1401-12. [PMID: 26974159 DOI: 10.1172/jci84005] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/28/2016] [Indexed: 12/29/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI3K) signaling pathway is central to the action of insulin and many growth factors. Heterozygous mutations in the gene encoding the p85α regulatory subunit of PI3K (PIK3R1) have been identified in patients with SHORT syndrome - a disorder characterized by short stature, partial lipodystrophy, and insulin resistance. Here, we evaluated whether SHORT syndrome-associated PIK3R1 mutations account for the pathophysiology that underlies the abnormalities by generating knockin mice that are heterozygous for the Pik3r1Arg649Trp mutation, which is homologous to the mutation found in the majority of affected individuals. Similar to the patients, mutant mice exhibited a reduction in body weight and length, partial lipodystrophy, and systemic insulin resistance. These derangements were associated with a reduced capacity of insulin and other growth factors to activate PI3K in liver, muscle, and fat; marked insulin resistance in liver and fat of mutation-harboring animals; and insulin resistance in vitro in cells derived from these mice. In addition, mutant mice displayed defective insulin secretion and GLP-1 action on islets in vivo and in vitro. These data demonstrate the ability of this heterozygous mutation to alter PI3K activity in vivo and the central role of PI3K in insulin/growth factor action, adipocyte function, and glucose metabolism.
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107
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Burkart AM, Tan K, Warren L, Iovino S, Hughes KJ, Kahn CR, Patti ME. Insulin Resistance in Human iPS Cells Reduces Mitochondrial Size and Function. Sci Rep 2016; 6:22788. [PMID: 26948272 PMCID: PMC4780029 DOI: 10.1038/srep22788] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/17/2016] [Indexed: 12/20/2022] Open
Abstract
Insulin resistance, a critical component of type 2 diabetes (T2D), precedes and predicts T2D onset. T2D is also associated with mitochondrial dysfunction. To define the cause-effect relationship between insulin resistance and mitochondrial dysfunction, we compared mitochondrial metabolism in induced pluripotent stem cells (iPSC) from 5 healthy individuals and 4 patients with genetic insulin resistance due to insulin receptor mutations. Insulin-resistant iPSC had increased mitochondrial number and decreased mitochondrial size. Mitochondrial oxidative function was impaired, with decreased citrate synthase activity and spare respiratory capacity. Simultaneously, expression of multiple glycolytic enzymes was decreased, while lactate production increased 80%. These perturbations were accompanied by an increase in ADP/ATP ratio and 3-fold increase in AMPK activity, indicating energetic stress. Insulin-resistant iPSC also showed reduced catalase activity and increased susceptibility to oxidative stress. Thus, insulin resistance can lead to mitochondrial dysfunction with reduced mitochondrial size, oxidative activity, and energy production.
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Affiliation(s)
- Alison M Burkart
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
| | - Kelly Tan
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
| | - Laura Warren
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
| | - Salvatore Iovino
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
| | - Katelyn J Hughes
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
| | - C Ronald Kahn
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
| | - Mary-Elizabeth Patti
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center and Harvard Medical School, Boston, MA, 02215, USA
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108
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Torriani M, Srinivasa S, Fitch KV, Thomou T, Wong K, Petrow E, Kahn CR, Cypess AM, Grinspoon SK. Dysfunctional Subcutaneous Fat With Reduced Dicer and Brown Adipose Tissue Gene Expression in HIV-Infected Patients. J Clin Endocrinol Metab 2016; 101:1225-34. [PMID: 26756119 PMCID: PMC4803164 DOI: 10.1210/jc.2015-3993] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT HIV patients are at an increased risk for cardiometabolic disease secondary to depot-specific alterations in adipose function, but mechanisms remain poorly understood. OBJECTIVE The endoribonuclease Dicer has been linked to the modulation of brown and white adipocyte differentiation. We previously demonstrated that Dicer knockout mice undergo transformation of brown adipose tissue to white adipose tissue and develop a lipodystrophic phenotype. We hypothesized reduced Dicer and brown adipose tissue gene expression from nonlipomatous sc fat among HIV patients with a lipodystrophic phenotype. DESIGN Eighteen HIV (nine with and without lipodystrophic changes in fat distribution, characterized by excess dorsocervical adipose tissue [DCAT]) and nine non-HIV subjects underwent punch biopsy of abdominal sc fat to determine expression of Dicer and other adipose-related genes. RESULTS HIV subjects with long-duration antiretroviral use demonstrated excess DCAT vs non-HIV subjects (9.8 ± 1.0 vs 6.6 ± 0.8 cm(2), P = .02) with similar body mass index. Dicer expression was decreased in abdominal sc fat of HIV vs non-HIV (4.88 [1.91, 11.93] vs 17.69 [10.72, 47.91], P = .01), as were PPARα, ZIC1, PRDM16, DIO2, and HSP60 (all P ≤ .03). Moreover, the expression of Dicer (2.49 [0.02, 4.88] vs 11.20 [4.83, 21.45], P = .006), brown fat (PPARα [P = .002], ZIC1 [P = .004], LHX8 [P = .03], PRDM16 [P = .0008], PAT2 [P = .008], P2RX5 [P = .02]), beige fat (TMEM26 [P = .004], CD137 [P = .008]), and other genes (DIO2 [P = .002], leptin [P = .003], HSP60 [P = .0004]) was further decreased in abdominal sc fat comparing HIV subjects with vs without excess DCAT. Down-regulation of Dicer in the abdominal sc fat correlated with the down-regulation of all brown and beige fat genes (all P ≤ .01). CONCLUSION Our results demonstrate dysfunctional sc adipose tissue marked by reduced Dicer in relationship to the down-regulation of brown and beige fat-related genes in lipodystrophic HIV patients and may provide a novel mechanism for metabolic dysregulation. A strategy to increase browning of white adipose tissue may improve cardiometabolic health in HIV.
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Affiliation(s)
- Martin Torriani
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Suman Srinivasa
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Kathleen V Fitch
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Thomas Thomou
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Kimberly Wong
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Eva Petrow
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - C Ronald Kahn
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Aaron M Cypess
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
| | - Steven K Grinspoon
- Program in Nutritional Metabolism (M.T., S.S., K.V.F., K.W., E.P., S.K.G.) and Division of Musculoskeletal Imaging and Intervention (M.T.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Section on Integrative Physiology and Metabolism (T.T., C.R.K., A.M.C.), Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215; and Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (A.M.C.), Bethesda, Maryland 20892
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Lagarrigue S, Lopez-Mejia IC, Denechaud PD, Escoté X, Castillo-Armengol J, Jimenez V, Chavey C, Giralt A, Lai Q, Zhang L, Martinez-Carreres L, Delacuisine B, Annicotte JS, Blanchet E, Huré S, Abella A, Tinahones FJ, Vendrell J, Dubus P, Bosch F, Kahn CR, Fajas L. CDK4 is an essential insulin effector in adipocytes. J Clin Invest 2015; 126:335-48. [PMID: 26657864 DOI: 10.1172/jci81480] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 11/06/2015] [Indexed: 12/11/2022] Open
Abstract
Insulin resistance is a fundamental pathogenic factor that characterizes various metabolic disorders, including obesity and type 2 diabetes. Adipose tissue contributes to the development of obesity-related insulin resistance through increased release of fatty acids, altered adipokine secretion, and/or macrophage infiltration and cytokine release. Here, we aimed to analyze the participation of the cyclin-dependent kinase 4 (CDK4) in adipose tissue biology. We determined that white adipose tissue (WAT) from CDK4-deficient mice exhibits impaired lipogenesis and increased lipolysis. Conversely, lipolysis was decreased and lipogenesis was increased in mice expressing a mutant hyperactive form of CDK4 (CDK4(R24C)). A global kinome analysis of CDK4-deficient mice following insulin stimulation revealed that insulin signaling is impaired in these animals. We determined that insulin activates the CCND3-CDK4 complex, which in turn phosphorylates insulin receptor substrate 2 (IRS2) at serine 388, thereby creating a positive feedback loop that maintains adipocyte insulin signaling. Furthermore, we found that CCND3 expression and IRS2 serine 388 phosphorylation are increased in human obese subjects. Together, our results demonstrate that CDK4 is a major regulator of insulin signaling in WAT.
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110
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Abstract
Protein kinase C (PKC)δ has been shown to be increased in liver in obesity and plays an important role in the development of hepatic insulin resistance in both mice and humans. In the current study, we explored the role of PKCδ in skeletal muscle in the control of insulin sensitivity and glucose metabolism by generating mice in which PKCδ was deleted specifically in muscle using Cre-lox recombination. Deletion of PKCδ in muscle improved insulin signaling in young mice, especially at low insulin doses; however, this did not change glucose tolerance or insulin tolerance tests done with pharmacological levels of insulin. Likewise, in young mice, muscle-specific deletion of PKCδ did not rescue high-fat diet-induced insulin resistance or glucose intolerance. However, with an increase in age, PKCδ levels in muscle increased, and by 6 to 7 months of age, muscle-specific deletion of PKCδ improved whole-body insulin sensitivity and muscle insulin resistance and by 15 months of age improved the age-related decline in whole-body glucose tolerance. At 15 months of age, M-PKCδKO mice also exhibited decreased metabolic rate and lower levels of some proteins of the OXPHOS complex suggesting a role for PKCδ in the regulation of mitochondrial mass at older age. These data indicate an important role of PKCδ in the regulation of insulin sensitivity and mitochondrial homeostasis in skeletal muscle with aging.
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Affiliation(s)
- Mengyao Li
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Sara G Vienberg
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA Novo Nordisk Foundation Center for Basic Metabolic Research, Copenhagen University, Copenhagen, Denmark
| | - Olivier Bezy
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Brian T O'Neill
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - C Ronald Kahn
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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111
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Ussar S, Lee KY, Dankel SN, Boucher J, Haering MF, Kleinridders A, Thomou T, Xue R, Macotela Y, Cypess AM, Tseng YH, Mellgren G, Kahn CR. ASC-1, PAT2, and P2RX5 are cell surface markers for white, beige, and brown adipocytes. Sci Transl Med 2015; 6:247ra103. [PMID: 25080478 DOI: 10.1126/scitranslmed.3008490] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
White, beige, and brown adipocytes are developmentally and functionally distinct but often occur mixed together within individual depots. To target white, beige, and brown adipocytes for diagnostic or therapeutic purposes, a better understanding of the cell surface properties of these cell types is essential. Using a combination of in silico, in vitro, and in vivo methods, we have identified three new cell surface markers of adipose cell types. The amino acid transporter ASC-1 is a white adipocyte-specific cell surface protein, with little or no expression in brown adipocytes, whereas the amino acid transporter PAT2 and the purinergic receptor P2RX5 are cell surface markers expressed in classical brown and beige adipocytes in mice. These markers also selectively mark brown/beige and white adipocytes in human tissue. Thus, ASC-1, PAT2, and P2RX5 are membrane surface proteins that may serve as tools to identify and target white and brown/beige adipocytes for therapeutic purposes.
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Affiliation(s)
- Siegfried Ussar
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA. Institute for Diabetes and Obesity, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Kevin Y Lee
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Simon N Dankel
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA. Department of Clinical Science, University of Bergen, 5020 Bergen, Norway. Hormone Laboratory, Haukeland University Hospital, 5020 Bergen, Norway
| | - Jeremie Boucher
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Max-Felix Haering
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Andre Kleinridders
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Thomas Thomou
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Ruidan Xue
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Yazmin Macotela
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Aaron M Cypess
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Yu-Hua Tseng
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Gunnar Mellgren
- Department of Clinical Science, University of Bergen, 5020 Bergen, Norway. Hormone Laboratory, Haukeland University Hospital, 5020 Bergen, Norway
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA.
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112
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Abstract
Diabetes mellitus is associated with a variety of complications, including alterations in the central nervous system (CNS). We have recently shown that diabetes results in a reduction of cholesterol synthesis in the brain due to decreased insulin stimulation of SREBP2-mediated cholesterol synthesis in neuronal and glial cells. In the present study, we explored the effects of the decrease in cholesterol on neuronal cell function using GT1-7 hypothalamic cells subjected to cholesterol depletion in vitro using three independent methods: 1) exposure to methyl-β-cyclodextrin, 2) treatment with the HMG-CoA reductase inhibitor simvastatin, and 3) shRNA-mediated knockdown of SREBP2. All three methods produced 20-31% reductions in cellular cholesterol content, similar to the decrease in cholesterol synthesis observed in diabetes. All cholesterol-depleted neuron-derived cells, independent of the method of reduction, exhibited decreased phosphorylation/activation of IRS-1 and AKT following stimulation by insulin, insulin-like growth factor-1, or the neurotrophins (NGF and BDNF). ERK phosphorylation/activation was also decreased after methyl-β-cyclodextrin and statin treatment but increased in cells following SREBP2 knockdown. In addition, apoptosis in the presence of amyloid-β was increased. Reduction in cellular cholesterol also resulted in increased basal autophagy and impairment of induction of autophagy by glucose deprivation. Together, these data indicate that a reduction in neuron-derived cholesterol content, similar to that observed in diabetic brain, creates a state of insulin and growth factor resistance that could contribute to CNS-related complications of diabetes, including increased risk of neurodegenerative diseases, such as Alzheimer disease.
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Affiliation(s)
- Kenji Fukui
- From the Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Heather A Ferris
- From the Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215
| | - C Ronald Kahn
- From the Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215
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113
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Ussar S, Griffin NW, Bezy O, Fujisaka S, Vienberg S, Softic S, Deng L, Bry L, Gordon JI, Kahn CR. Interactions between Gut Microbiota, Host Genetics and Diet Modulate the Predisposition to Obesity and Metabolic Syndrome. Cell Metab 2015; 22:516-530. [PMID: 26299453 PMCID: PMC4570502 DOI: 10.1016/j.cmet.2015.07.007] [Citation(s) in RCA: 378] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 06/03/2015] [Accepted: 07/06/2015] [Indexed: 12/12/2022]
Abstract
Obesity, diabetes, and metabolic syndrome result from complex interactions between genetic and environmental factors, including the gut microbiota. To dissect these interactions, we utilized three commonly used inbred strains of mice-obesity/diabetes-prone C57Bl/6J mice, obesity/diabetes-resistant 129S1/SvImJ from Jackson Laboratory, and obesity-prone but diabetes-resistant 129S6/SvEvTac from Taconic-plus three derivative lines generated by breeding these strains in a new, common environment. Analysis of metabolic parameters and gut microbiota in all strains and their environmentally normalized derivatives revealed strong interactions between microbiota, diet, breeding site, and metabolic phenotype. Strain-dependent and strain-independent correlations were found between specific microbiota and phenotypes, some of which could be transferred to germ-free recipient animals by fecal transplantation. Environmental reprogramming of microbiota resulted in 129S6/SvEvTac becoming obesity resistant. Thus, development of obesity/metabolic syndrome is the result of interactions between gut microbiota, host genetics, and diet. In permissive genetic backgrounds, environmental reprograming of microbiota can ameliorate development of metabolic syndrome.
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Affiliation(s)
- Siegfried Ussar
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Center Munich, Munich, 85764, Germany
| | - Nicholas W. Griffin
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63108
- Center for Gut Microbiome and Nutrition Research, Washington University School of Medicine, St. Louis, MO 63108
| | - Olivier Bezy
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215
| | - Shiho Fujisaka
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215
| | - Sara Vienberg
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215
| | - Samir Softic
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215
| | - Luxue Deng
- Center for Clinical and Translational Metagenomics, Department of Pathology, Brigham & Women's Hospital Harvard Medical School, Boston, MA, 021115
| | - Lynn Bry
- Center for Clinical and Translational Metagenomics, Department of Pathology, Brigham & Women's Hospital Harvard Medical School, Boston, MA, 021115
| | - Jeffrey I. Gordon
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63108
- Center for Gut Microbiome and Nutrition Research, Washington University School of Medicine, St. Louis, MO 63108
| | - C. Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215
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114
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Lee KY, Singh MK, Ussar S, Wetzel P, Hirshman MF, Goodyear LJ, Kispert A, Kahn CR. Tbx15 controls skeletal muscle fibre-type determination and muscle metabolism. Nat Commun 2015; 6:8054. [PMID: 26299309 PMCID: PMC4552045 DOI: 10.1038/ncomms9054] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 07/13/2015] [Indexed: 01/15/2023] Open
Abstract
Skeletal muscle is composed of both slow-twitch oxidative myofibers and fast-twitch glycolytic myofibers that differentially impact muscle metabolism, function and eventually whole-body physiology. Here we show that the mesodermal transcription factor T-box 15 (Tbx15) is highly and specifically expressed in glycolytic myofibers. Ablation of Tbx15 in vivo leads to a decrease in muscle size due to a decrease in the number of glycolytic fibres, associated with a small increase in the number of oxidative fibres. This shift in fibre composition results in muscles with slower myofiber contraction and relaxation, and also decreases whole-body oxygen consumption, reduces spontaneous activity, increases adiposity and glucose intolerance. Mechanistically, ablation of Tbx15 leads to activation of AMPK signalling and a decrease in Igf2 expression. Thus, Tbx15 is one of a limited number of transcription factors to be identified with a critical role in regulating glycolytic fibre identity and muscle metabolism. The transcriptional regulator Tbx15 has a role in organ development. Here Lee et al. show that Tbx15 influences fibre-type determination in murine skeletal muscles, explaining local and systemic metabolic derangements in heterozygous Tbx15 knockout mice.
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Affiliation(s)
- Kevin Y Lee
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, 1 Joslin Plaza, Boston, Massachusetts 02215, USA
| | - Manvendra K Singh
- Institut für Molekularbiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.,Signature Research Program in Cardiovascular and Metabolic Disorders, Duke-NUS Graduate Medical School Singapore, National Heart Centre Singapore, 8 College Road, Singapore 169857, Singapore
| | - Siegfried Ussar
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, 1 Joslin Plaza, Boston, Massachusetts 02215, USA.,Institute for Diabetes and Obesity, Helmholtz Center, Parkring, 1385748 Munich/Garching, Germany
| | - Petra Wetzel
- Zentrum Physiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Michael F Hirshman
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, 1 Joslin Plaza, Boston, Massachusetts 02215, USA
| | - Laurie J Goodyear
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, 1 Joslin Plaza, Boston, Massachusetts 02215, USA
| | - Andreas Kispert
- Institut für Molekularbiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, 1 Joslin Plaza, Boston, Massachusetts 02215, USA
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115
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DeFronzo RA, Ferrannini E, Groop L, Henry RR, Herman WH, Holst JJ, Hu FB, Kahn CR, Raz I, Shulman GI, Simonson DC, Testa MA, Weiss R. Type 2 diabetes mellitus. Nat Rev Dis Primers 2015; 1:15019. [PMID: 27189025 DOI: 10.1038/nrdp.2015.19] [Citation(s) in RCA: 982] [Impact Index Per Article: 109.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is an expanding global health problem, closely linked to the epidemic of obesity. Individuals with T2DM are at high risk for both microvascular complications (including retinopathy, nephropathy and neuropathy) and macrovascular complications (such as cardiovascular comorbidities), owing to hyperglycaemia and individual components of the insulin resistance (metabolic) syndrome. Environmental factors (for example, obesity, an unhealthy diet and physical inactivity) and genetic factors contribute to the multiple pathophysiological disturbances that are responsible for impaired glucose homeostasis in T2DM. Insulin resistance and impaired insulin secretion remain the core defects in T2DM, but at least six other pathophysiological abnormalities contribute to the dysregulation of glucose metabolism. The multiple pathogenetic disturbances present in T2DM dictate that multiple antidiabetic agents, used in combination, will be required to maintain normoglycaemia. The treatment must not only be effective and safe but also improve the quality of life. Several novel medications are in development, but the greatest need is for agents that enhance insulin sensitivity, halt the progressive pancreatic β-cell failure that is characteristic of T2DM and prevent or reverse the microvascular complications. For an illustrated summary of this Primer, visit: http://go.nature.com/V2eGfN.
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Affiliation(s)
- Ralph A DeFronzo
- Diabetes Division, Department of Medicine, University of Texas Health Science Center, South Texas Veterans Health Care System and Texas Diabetes Institute, 701 S. Zarzamoro, San Antonio, Texas 78207, USA
| | | | - Leif Groop
- Department of Clinical Science Malmoe, Diabetes &Endocrinology, Lund University Diabetes Centre, Lund, Sweden
| | - Robert R Henry
- University of California, San Diego, Section of Diabetes, Endocrinology &Metabolism, Center for Metabolic Research, VA San Diego Healthcare System, San Diego, California, USA
| | | | | | - Frank B Hu
- Department of Nutrition, Harvard T.H. Chan School of Public Health and Department of Epidemiology, Harvard T.H. Chan School of Public Health and Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - C Ronald Kahn
- Harvard Medical School and Joslin Diabetes Center, Boston, Massachusetts, USA
| | - Itamar Raz
- Diabetes Unit, Division of Internal Medicine, Hadassah Hebrew University Hospital, Jerusalem, Israel
| | - Gerald I Shulman
- Howard Hughes Medical Institute and the Departments of Internal Medicine and Cellular &Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Donald C Simonson
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Marcia A Testa
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Ram Weiss
- Department of Human Metabolism and Nutrition, Braun School of Public Health, Hebrew University, Jerusalem, Israel
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116
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Wong SL, Demers M, Martinod K, Gallant M, Wang Y, Goldfine AB, Kahn CR, Wagner DD. Diabetes primes neutrophils to undergo NETosis, which impairs wound healing. Nat Med 2015; 21:815-9. [PMID: 26076037 DOI: 10.1038/nm.3887] [Citation(s) in RCA: 709] [Impact Index Per Article: 78.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/22/2015] [Indexed: 02/07/2023]
Abstract
Wound healing is impaired in diabetes, resulting in significant morbidity and mortality. Neutrophils are the main leukocytes involved in the early phase of healing. As part of their anti-microbial defense, neutrophils form extracellular traps (NETs) by releasing decondensed chromatin lined with cytotoxic proteins. NETs, however, can also induce tissue damage. Here we show that neutrophils isolated from type 1 and type 2 diabetic humans and mice were primed to produce NETs (a process termed NETosis). Expression of peptidylarginine deiminase 4 (PAD4, encoded by Padi4 in mice), an enzyme important in chromatin decondensation, was elevated in neutrophils from individuals with diabetes. When subjected to excisional skin wounds, wild-type (WT) mice produced large quantities of NETs in wounds, but this was not observed in Padi4(-/-) mice. In diabetic mice, higher levels of citrullinated histone H3 (H3Cit, a NET marker) were found in their wounds than in normoglycemic mice and healing was delayed. Wound healing was accelerated in Padi4(-/-) mice as compared to WT mice, and it was not compromised by diabetes. DNase 1, which disrupts NETs, accelerated wound healing in diabetic and normoglycemic WT mice. Thus, NETs impair wound healing, particularly in diabetes, in which neutrophils are more susceptible to NETosis. Inhibiting NETosis or cleaving NETs may improve wound healing and reduce NET-driven chronic inflammation in diabetes.
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Affiliation(s)
- Siu Ling Wong
- 1] Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA. [2] Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Melanie Demers
- 1] Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA. [2] Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Kimberly Martinod
- 1] Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA. [2] Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Maureen Gallant
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Yanming Wang
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Allison B Goldfine
- Section of Clinical Research, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Denisa D Wagner
- 1] Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA. [2] Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA. [3] Division of Hematology/Oncology, Boston Children's Hospital, Boston, Massachusetts, USA
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117
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Abstract
Donohue syndrome (DS) is characterized by severe insulin resistance due to mutations in the insulin receptor (INSR) gene. To identify molecular defects contributing to metabolic dysregulation in DS in the undifferentiated state, we generated mesenchymal progenitor cells (MPCs) from induced pluripotent stem cells derived from a 4-week-old female with DS and a healthy newborn male (control). INSR mRNA and protein were significantly reduced in DS MPC (for β-subunit, 64% and 89% reduction, respectively, P < .05), but IGF1R mRNA and protein did not differ vs control. Insulin-stimulated phosphorylation of INSR or the downstream substrates insulin receptor substrate 1 and protein kinase B did not differ, but ERK phosphorylation tended to be reduced in DS (32% decrease, P = .07). By contrast, IGF-1 and insulin-stimulated insulin-like growth factor 1 (IGF-1) receptor phosphorylation were increased in DS (IGF-1, 8.5- vs 4.5-fold increase; INS, 11- vs 6-fold; P < .05). DS MPC tended to have higher oxygen consumption in both the basal state (87% higher, P =.09) and in response to the uncoupler carbonyl cyanide-p-triflouromethoxyphenylhydrazone (2-fold increase, P =.06). Although mitochondrial DNA or mass did not differ, oxidative phosphorylation protein complexes III and V were increased in DS (by 37% and 6%, respectively; P < .05). Extracellular acidification also tended to increase in DS (91% increase, P = .07), with parallel significant increases in lactate secretion (34% higher at 4 h, P < .05). In summary, DS MPC maintain signaling downstream of the INSR, suggesting that IGF-1R signaling may partly compensate for INSR mutations. However, alterations in receptor expression and pathway-specific defects in insulin signaling, even in undifferentiated cells, can alter cellular oxidative metabolism, potentially via transcriptional mechanisms.
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Affiliation(s)
- Bharti Balhara
- Research Division (B.B., A.B., V.T., R.K., C.R.K., M.-E.P.), Joslin Diabetes Center, Boston, Massachusetts 02215; Department of Stem Cell and Regenerative Biology (Y.-K.L., C.C.), Harvard University, Cambridge, Massachusetts 02138; and Center for Regenerative Medicine and Cardiovascular Research Center (Y.-K.L., C.C.), Massachusetts General Hospital, Boston, Massachusetts 02114
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118
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O'Neill BT, Lauritzen HPMM, Hirshman MF, Smyth G, Goodyear LJ, Kahn CR. Differential Role of Insulin/IGF-1 Receptor Signaling in Muscle Growth and Glucose Homeostasis. Cell Rep 2015; 11:1220-35. [PMID: 25981038 DOI: 10.1016/j.celrep.2015.04.037] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 03/11/2015] [Accepted: 04/17/2015] [Indexed: 11/29/2022] Open
Abstract
Insulin and insulin-like growth factor 1 (IGF-1) are major regulators of muscle protein and glucose homeostasis. To determine how these pathways interact, we generated mice with muscle-specific knockout of IGF-1 receptor (IGF1R) and insulin receptor (IR). These MIGIRKO mice showed >60% decrease in muscle mass. Despite a complete lack of insulin/IGF-1 signaling in muscle, MIGIRKO mice displayed normal glucose and insulin tolerance. Indeed, MIGIRKO mice showed fasting hypoglycemia and increased basal glucose uptake. This was secondary to decreased TBC1D1 resulting in increased Glut4 and Glut1 membrane localization. Interestingly, overexpression of a dominant-negative IGF1R in muscle induced glucose intolerance in MIGIRKO animals. Thus, loss of insulin/IGF-1 signaling impairs muscle growth, but not whole-body glucose tolerance due to increased membrane localization of glucose transporters. Nonetheless, presence of a dominant-negative receptor, even in the absence of functional IR/IGF1R, induces glucose intolerance, indicating that interactions between these receptors and other proteins in muscle can impair glucose homeostasis.
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Affiliation(s)
- Brian T O'Neill
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Hans P M M Lauritzen
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Michael F Hirshman
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Graham Smyth
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Laurie J Goodyear
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA.
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119
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O-Sullivan I, Zhang W, Wasserman DH, Liew CW, Liu J, Paik J, DePinho RA, Stolz DB, Kahn CR, Schwartz MW, Unterman TG. FoxO1 integrates direct and indirect effects of insulin on hepatic glucose production and glucose utilization. Nat Commun 2015; 6:7079. [PMID: 25963540 DOI: 10.1038/ncomms8079] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 04/01/2015] [Indexed: 12/18/2022] Open
Abstract
FoxO proteins are major targets of insulin action. To better define the role of FoxO1 in mediating insulin effects in the liver, we generated liver-specific insulin receptor knockout (LIRKO) and IR/FoxO1 double knockout (LIRFKO) mice. Here we show that LIRKO mice are severely insulin resistant based on glucose, insulin and C-peptide levels, and glucose and insulin tolerance tests, and genetic deletion of hepatic FoxO1 reverses these effects. (13)C-glucose and insulin clamp studies indicate that regulation of both hepatic glucose production (HGP) and glucose utilization is impaired in LIRKO mice, and these defects are also restored in LIRFKO mice corresponding to changes in gene expression. We conclude that (1) inhibition of FoxO1 is critical for both direct (hepatic) and indirect effects of insulin on HGP and utilization, and (2) extrahepatic effects of insulin are sufficient to maintain normal whole-body and hepatic glucose metabolism when liver FoxO1 activity is disrupted.
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Affiliation(s)
- InSug O-Sullivan
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA
| | - Wenwei Zhang
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt Medical School, Nashville, Tennesse 37232, USA
| | - Chong Wee Liew
- Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA
| | - Jonathan Liu
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA
| | - Jihye Paik
- Dana Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | | | - Donna Beer Stolz
- Department of Cell Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - C Ronald Kahn
- Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Michael W Schwartz
- Diabetes and Obesity Center of Excellence, University of Washington, Seattle, Washington 98104, USA
| | - Terry G Unterman
- 1] Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA [2] Medical Service, Jesse Brown VA Medical Center, 820 South Damen Avenue, Chicago, Illinois 60612, USA, USA
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120
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Emanuelli B, Vienberg SG, Smyth G, Cheng C, Stanford KI, Arumugam M, Michael MD, Adams AC, Kharitonenkov A, Kahn CR. Interplay between FGF21 and insulin action in the liver regulates metabolism. J Clin Invest 2015; 125:458. [PMID: 25654556 DOI: 10.1172/jci80223] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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121
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Iovino S, Burkart AM, Kriauciunas K, Warren L, Hughes KJ, Molla M, Lee YK, Patti ME, Kahn CR. Genetic insulin resistance is a potent regulator of gene expression and proliferation in human iPS cells. Diabetes 2014; 63:4130-42. [PMID: 25059784 PMCID: PMC4238001 DOI: 10.2337/db14-0109] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Insulin resistance is central to diabetes and metabolic syndrome. To define the consequences of genetic insulin resistance distinct from those secondary to cellular differentiation or in vivo regulation, we generated induced pluripotent stem cells (iPSCs) from individuals with insulin receptor mutations and age-appropriate control subjects and studied insulin signaling and gene expression compared with the fibroblasts from which they were derived. iPSCs from patients with genetic insulin resistance exhibited altered insulin signaling, paralleling that seen in the original fibroblasts. Insulin-stimulated expression of immediate early genes and proliferation were also potently reduced in insulin resistant iPSCs. Global gene expression analysis revealed marked differences in both insulin-resistant iPSCs and corresponding fibroblasts compared with control iPSCs and fibroblasts. Patterns of gene expression in patients with genetic insulin resistance were particularly distinct in the two cell types, indicating dependence on not only receptor activity but also the cellular context of the mutant insulin receptor. Thus, iPSCs provide a novel approach to define effects of genetically determined insulin resistance. This study demonstrates that effects of insulin resistance on gene expression are modified by cellular context and differentiation state. Moreover, altered insulin receptor signaling and insulin resistance can modify proliferation and function of pluripotent stem cell populations.
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Affiliation(s)
- Salvatore Iovino
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Alison M Burkart
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Kristina Kriauciunas
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Laura Warren
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Katelyn J Hughes
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Michael Molla
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Youn-Kyoung Lee
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA
| | - Mary-Elizabeth Patti
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - C Ronald Kahn
- Integrative Physiology and Metabolism Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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Vernochet C, Damilano F, Mourier A, Bezy O, Mori MA, Smyth G, Rosenzweig A, Larsson NG, Kahn CR. Adipose tissue mitochondrial dysfunction triggers a lipodystrophic syndrome with insulin resistance, hepatosteatosis, and cardiovascular complications. FASEB J 2014; 28:4408-19. [PMID: 25005176 PMCID: PMC4202105 DOI: 10.1096/fj.14-253971] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/16/2014] [Indexed: 12/11/2022]
Abstract
Mitochondrial dysfunction in adipose tissue occurs in obesity, type 2 diabetes, and some forms of lipodystrophy, but whether this dysfunction contributes to or is the result of these disorders is unknown. To investigate the physiological consequences of severe mitochondrial impairment in adipose tissue, we generated mice deficient in mitochondrial transcription factor A (TFAM) in adipocytes by using mice carrying adiponectin-Cre and TFAM floxed alleles. These adiponectin TFAM-knockout (adipo-TFAM-KO) mice had a 75-81% reduction in TFAM in the subcutaneous and intra-abdominal white adipose tissue (WAT) and interscapular brown adipose tissue (BAT), causing decreased expression and enzymatic activity of proteins in complexes I, III, and IV of the electron transport chain (ETC). This mitochondrial dysfunction led to adipocyte death and inflammation in WAT and a whitening of BAT. As a result, adipo-TFAM-KO mice were resistant to weight gain, but exhibited insulin resistance on both normal chow and high-fat diets. These lipodystrophic mice also developed hypertension, cardiac hypertrophy, and cardiac dysfunction. Thus, isolated mitochondrial dysfunction in adipose tissue can lead a syndrome of lipodystrophy with metabolic syndrome and cardiovascular complications.
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Affiliation(s)
- Cecile Vernochet
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Federico Damilano
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA; Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; and
| | - Arnaud Mourier
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Olivier Bezy
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Marcelo A Mori
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Graham Smyth
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Anthony Rosenzweig
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA; Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; and
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA;
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Neithercott T, Shockley C, Kahn CR, Smith C, Wilkins D, Garnero T, Hathaway K, Angell C, Panzirer D, Tamler R, Wahowiak L. People to know 2014. Diabetes Forecast 2014; 67:40-49. [PMID: 25546888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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124
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Pensa S, Lloyd-Lewis B, Sargeant TJ, Resemann HK, Kahn CR, Watson CJ. Signal transducer and activator of transcription 3 and the phosphatidylinositol 3-kinase regulatory subunits p55α and p50α regulate autophagy in vivo. FEBS J 2014; 281:4557-67. [PMID: 25205393 DOI: 10.1111/febs.13035] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 08/11/2014] [Accepted: 09/02/2014] [Indexed: 02/04/2023]
Abstract
Mammary gland involution involves a process that includes one of the most dramatic examples of cell death in an adult mammalian organism. We have previously shown that signal transducer and activator of transcription 3 (Stat3) regulates a lysosomal pathway of cell death in the first 48 h of involution and induces lysosome leakiness in mammary epithelial cells. Interestingly, Stat3 is associated also with the striking induction of autophagy that occurs concomitantly with cell death, presumably as a transient survival mechanism. The phosphatidylinositol 3-kinase regulatory subunits p55α and p50α are dramatically and specifically upregulated at the transcriptional level by Stat3 at the onset of involution. We show here that ablation of either Stat3 or p55α/p50α in vivo affects autophagy during involution. We used two different cell culture models (normal mammary epithelial cells and mouse embryonic fibroblasts) to further investigate the role of p55α/p50α in autophagy regulation. Our results demonstrate a direct role for p55α/p50α as inhibitors of autophagy mediated by p85α. Thus, Stat3 and its downstream targets p55α/p50α are key regulators of the balance between autophagy and cell death in vivo.
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Affiliation(s)
- Sara Pensa
- Department of Pathology, University of Cambridge, Cambridge, UK
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125
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Samocha-Bonet D, Dixit VD, Kahn CR, Leibel RL, Lin X, Nieuwdorp M, Pietiläinen KH, Rabasa-Lhoret R, Roden M, Scherer PE, Klein S, Ravussin E. Metabolically healthy and unhealthy obese--the 2013 Stock Conference report. Obes Rev 2014; 15:697-708. [PMID: 25059108 PMCID: PMC4519075 DOI: 10.1111/obr.12199] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 05/16/2014] [Accepted: 05/18/2014] [Indexed: 12/12/2022]
Abstract
Obesity is closely associated with cardiovascular diseases and type 2 diabetes, but some obese individuals, despite having excessive body fat, exhibit metabolic health that is comparable with that of lean individuals. The 'healthy obese' phenotype was described in the 1980s, but major advancements in its characterization were only made in the past five years. During this time, several new mechanisms that may be involved in health preservation in obesity were proposed through the use of transgenic animal models, use of sophisticated imaging techniques and in vivo measurements of insulin sensitivity. However, the main obstacle in advancing our understanding of the metabolically healthy obese phenotype and its related long-term health risks is the lack of a standardized definition. Here, we summarize the proceedings of the 13th Stock Conference of the International Association of the Study of Obesity. We describe the current research and highlight the unanswered questions and gaps in the field. Better understanding of metabolic health in obesity will assist in therapeutic decision-making and help identify therapeutic targets to improve metabolic health in obesity.
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Affiliation(s)
- D Samocha-Bonet
- Garvan Institute of Medical Research, University of New South Wales, Sydney, NSW, Australia
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126
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Mori MA, Thomou T, Boucher J, Lee KY, Lallukka S, Kim JK, Torriani M, Yki-Järvinen H, Grinspoon SK, Cypess AM, Kahn CR. Altered miRNA processing disrupts brown/white adipocyte determination and associates with lipodystrophy. J Clin Invest 2014; 124:3339-51. [PMID: 24983316 DOI: 10.1172/jci73468] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 05/22/2014] [Indexed: 12/17/2022] Open
Abstract
miRNAs are important regulators of biological processes in many tissues, including the differentiation and function of brown and white adipocytes. The endoribonuclease dicer is a major component of the miRNA-processing pathway, and in adipose tissue, levels of dicer have been shown to decrease with age, increase with caloric restriction, and influence stress resistance. Here, we demonstrated that mice with a fat-specific KO of dicer develop a form of lipodystrophy that is characterized by loss of intra-abdominal and subcutaneous white fat, severe insulin resistance, and enlargement and "whitening" of interscapular brown fat. Additionally, KO of dicer in cultured brown preadipocytes promoted a white adipocyte-like phenotype and reduced expression of several miRNAs. Brown preadipocyte whitening was partially reversed by expression of miR-365, a miRNA known to promote brown fat differentiation; however, introduction of other miRNAs, including miR-346 and miR-362, also contributed to reversal of the loss of the dicer phenotype. Interestingly, fat samples from patients with HIV-related lipodystrophy exhibited a substantial downregulation of dicer mRNA expression. Together, these findings indicate the importance of miRNA processing in white and brown adipose tissue determination and provide a potential link between this process and HIV-related lipodystrophy.
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127
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Abstract
Insulin receptors, as well as IGF-1 receptors and their postreceptor signaling partners, are distributed throughout the brain. Insulin acts on these receptors to modulate peripheral metabolism, including regulation of appetite, reproductive function, body temperature, white fat mass, hepatic glucose output, and response to hypoglycemia. Insulin signaling also modulates neurotransmitter channel activity, brain cholesterol synthesis, and mitochondrial function. Disruption of insulin action in the brain leads to impairment of neuronal function and synaptogenesis. In addition, insulin signaling modulates phosphorylation of tau protein, an early component in the development of Alzheimer disease. Thus, alterations in insulin action in the brain can contribute to metabolic syndrome, and the development of mood disorders and neurodegenerative diseases.
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Affiliation(s)
- André Kleinridders
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Heather A Ferris
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Weikang Cai
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
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128
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Kleinridders A, Lauritzen HPMM, Ussar S, Christensen JH, Mori MA, Bross P, Kahn CR. Leptin regulation of Hsp60 impacts hypothalamic insulin signaling. J Clin Invest 2014; 123:4667-80. [PMID: 24084737 DOI: 10.1172/jci67615] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 08/01/2013] [Indexed: 11/17/2022] Open
Abstract
Type 2 diabetes is characterized by insulin resistance and mitochondrial dysfunction in classical target tissues such as muscle, fat, and liver. Using a murine model of type 2 diabetes, we show that there is hypothalamic insulin resistance and mitochondrial dysfunction due to downregulation of the mitochondrial chaperone HSP60. HSP60 reduction in obese, diabetic mice was due to a lack of proper leptin signaling and was restored by leptin treatment. Knockdown of Hsp60 in a mouse hypothalamic cell line mimicked the mitochondrial dysfunction observed in diabetic mice and resulted in increased ROS production and insulin resistance, a phenotype that was reversed with antioxidant treatment. Mice with a heterozygous deletion of Hsp60 exhibited mitochondrial dysfunction and hypothalamic insulin resistance. Targeted acute downregulation of Hsp60 in the hypothalamus also induced insulin resistance, indicating that mitochondrial dysfunction can cause insulin resistance in the hypothalamus. Importantly, type 2 diabetic patients exhibited decreased expression of HSP60 in the brain, indicating that this mechanism is relevant to human disease. These data indicate that leptin plays an important role in mitochondrial function and insulin sensitivity in the hypothalamus by regulating HSP60. Moreover, leptin/insulin crosstalk in the hypothalamus impacts energy homeostasis in obesity and insulin-resistant states.
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129
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Emanuelli B, Vienberg SG, Smyth G, Cheng C, Stanford KI, Arumugam M, Michael MD, Adams AC, Kharitonenkov A, Kahn CR. Interplay between FGF21 and insulin action in the liver regulates metabolism. J Clin Invest 2014; 124:515-27. [PMID: 24401271 DOI: 10.1172/jci67353] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 10/24/2013] [Indexed: 12/20/2022] Open
Abstract
The hormone FGF21 regulates carbohydrate and lipid homeostasis as well as body weight, and increasing FGF21 improves metabolic abnormalities associated with obesity and diabetes. FGF21 is thought to act on its target tissues, including liver and adipose tissue, to improve insulin sensitivity and reduce adiposity. Here, we used mice with selective hepatic inactivation of the IR (LIRKO) to determine whether insulin sensitization in liver mediates FGF21 metabolic actions. Remarkably, hyperglycemia was completely normalized following FGF21 treatment in LIRKO mice, even though FGF21 did not reduce gluconeogenesis in these animals. Improvements in blood sugar were due in part to increased glucose uptake in brown fat, browning of white fat, and overall increased energy expenditure. These effects were preserved even after removal of the main interscapular brown fat pad. In contrast to its retained effects on reducing glucose levels, the effects of FGF21 on reducing circulating cholesterol and hepatic triglycerides and regulating the expression of key genes involved in cholesterol and lipid metabolism in liver were disrupted in LIRKO mice. Thus, FGF21 corrects hyperglycemia in diabetic mice independently of insulin action in the liver by increasing energy metabolism via activation of brown fat and browning of white fat, but intact liver insulin action is required for FGF21 to control hepatic lipid metabolism.
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130
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Abstract
In the wake of the worldwide increase in type-2 diabetes, a major focus of research is understanding the signaling pathways impacting this disease. Insulin signaling regulates glucose, lipid, and energy homeostasis, predominantly via action on liver, skeletal muscle, and adipose tissue. Precise modulation of this pathway is vital for adaption as the individual moves from the fed to the fasted state. The positive and negative modulators acting on different steps of the signaling pathway, as well as the diversity of protein isoform interaction, ensure a proper and coordinated biological response to insulin in different tissues. Whereas genetic mutations are causes of rare and severe insulin resistance, obesity can lead to insulin resistance through a variety of mechanisms. Understanding these pathways is essential for development of new drugs to treat diabetes, metabolic syndrome, and their complications.
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Affiliation(s)
- Jérémie Boucher
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
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131
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Thrailkill K, Bunn RC, Lumpkin C, Wahl E, Cockrell G, Morris L, Kahn CR, Fowlkes J, Nyman JS. Loss of insulin receptor in osteoprogenitor cells impairs structural strength of bone. J Diabetes Res 2014; 2014:703589. [PMID: 24963495 PMCID: PMC4052184 DOI: 10.1155/2014/703589] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/30/2014] [Indexed: 12/11/2022] Open
Abstract
Type 1 diabetes mellitus (T1D) is associated with decreased bone mineral density, a deficit in bone structure, and subsequently an increased risk of fragility fracture. These clinical observations, paralleled by animal models of T1D, suggest that the insulinopenia of T1D has a deleterious effect on bone. To further examine the action of insulin signaling on bone development, we generated mice with an osteoprogenitor-selective (osterix-Cre) ablation of the insulin receptor (IR), designated OIRKO. OIRKO mice exhibited an 80% decrease in IR in osteoblasts. Prenatal elimination of IR did not affect fetal survival or gross morphology. However, loss of IR in mouse osteoblasts resulted in a postnatal growth-constricted phenotype. By 10-12 weeks of age, femurs of OIRKO mice were more slender, with a thinner diaphyseal cortex and, consequently, a decrease in whole bone strength when subjected to bending. In male mice alone, decreased metaphyseal trabecular bone, with thinner and more rodlike trabeculae, was also observed. OIRKO mice did not, however, exhibit abnormal glucose tolerance. The skeletal phenotype of the OIRKO mouse appeared more severe than that of previously reported bone-specific IR knockdown models, and confirms that insulin receptor expression in osteoblasts is critically important for proper bone development and maintenance of structural integrity.
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Affiliation(s)
- Kathryn Thrailkill
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Arkansas Children's Hospital, 1 Children's Way, Slot 512-6, Little Rock, AR 72202, USA
- *Kathryn Thrailkill:
| | - R. Clay Bunn
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Charles Lumpkin
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Arkansas Children's Hospital Research Institute, Little Rock, AR, USA
| | - Elizabeth Wahl
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Arkansas Children's Hospital Research Institute, Little Rock, AR, USA
| | - Gael Cockrell
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Lindsey Morris
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - C. Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, Boston, MA, USA
| | - John Fowlkes
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jeffry S. Nyman
- VA Tennessee Valley Health Care System, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Orthopaedic Surgery & Rehabilitation, Vanderbilt University Medical Center, Nashville, TN, USA
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA
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132
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Xu C, Tabebordbar M, Iovino S, Ciarlo C, Liu J, Castiglioni A, Price E, Liu M, Barton ER, Kahn CR, Wagers AJ, Zon LI. A zebrafish embryo culture system defines factors that promote vertebrate myogenesis across species. Cell 2013; 155:909-921. [PMID: 24209627 PMCID: PMC3902670 DOI: 10.1016/j.cell.2013.10.023] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 08/29/2013] [Accepted: 10/11/2013] [Indexed: 01/05/2023]
Abstract
Ex vivo expansion of satellite cells and directed differentiation of pluripotent cells to mature skeletal muscle have proved difficult challenges for regenerative biology. Using a zebrafish embryo culture system with reporters of early and late skeletal muscle differentiation, we examined the influence of 2,400 chemicals on myogenesis and identified six that expanded muscle progenitors, including three GSK3β inhibitors, two calpain inhibitors, and one adenylyl cyclase activator, forskolin. Forskolin also enhanced proliferation of mouse satellite cells in culture and maintained their ability to engraft muscle in vivo. A combination of bFGF, forskolin, and the GSK3β inhibitor BIO induced skeletal muscle differentiation in human induced pluripotent stem cells (iPSCs) and produced engraftable myogenic progenitors that contributed to muscle repair in vivo. In summary, these studies reveal functionally conserved pathways regulating myogenesis across species and identify chemical compounds that expand mouse satellite cells and differentiate human iPSCs into engraftable muscle.
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Affiliation(s)
- Cong Xu
- Division of Hematology/Oncology, Children’s Hospital Boston and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Mohammadsharif Tabebordbar
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
| | - Salvatore Iovino
- Harvard Medical School, Boston, MA 02115, USA
- Joslin Diabetes Center, Boston, MA 02115, USA
| | - Christie Ciarlo
- Division of Hematology/Oncology, Children’s Hospital Boston and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Jingxia Liu
- Division of Hematology/Oncology, Children’s Hospital Boston and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Alessandra Castiglioni
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Joslin Diabetes Center, Boston, MA 02115, USA
- Vita-Salute San Raffaele University, Milan, 20132, Italy
| | - Emily Price
- Division of Hematology/Oncology, Children’s Hospital Boston and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Min Liu
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Elisabeth R. Barton
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - C. Ronald Kahn
- Harvard Medical School, Boston, MA 02115, USA
- Joslin Diabetes Center, Boston, MA 02115, USA
| | - Amy J. Wagers
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
- Joslin Diabetes Center, Boston, MA 02115, USA
| | - Leonard I. Zon
- Division of Hematology/Oncology, Children’s Hospital Boston and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Stem Cell Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
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133
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Jing E, O’Neill BT, Rardin MJ, Kleinridders A, Ilkeyeva OR, Ussar S, Bain JR, Lee KY, Verdin EM, Newgard CB, Gibson BW, Kahn CR. Sirt3 regulates metabolic flexibility of skeletal muscle through reversible enzymatic deacetylation. Diabetes 2013; 62:3404-17. [PMID: 23835326 PMCID: PMC3781465 DOI: 10.2337/db12-1650] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Sirt3 is an NAD(+)-dependent deacetylase that regulates mitochondrial function by targeting metabolic enzymes and proteins. In fasting mice, Sirt3 expression is decreased in skeletal muscle resulting in increased mitochondrial protein acetylation. Deletion of Sirt3 led to impaired glucose oxidation in muscle, which was associated with decreased pyruvate dehydrogenase (PDH) activity, accumulation of pyruvate and lactate metabolites, and an inability of insulin to suppress fatty acid oxidation. Antibody-based acetyl-peptide enrichment and mass spectrometry of mitochondrial lysates from WT and Sirt3 KO skeletal muscle revealed that a major target of Sirt3 deacetylation is the E1α subunit of PDH (PDH E1α). Sirt3 knockout in vivo and Sirt3 knockdown in myoblasts in vitro induced hyperacetylation of the PDH E1α subunit, altering its phosphorylation leading to suppressed PDH enzymatic activity. The inhibition of PDH activity resulting from reduced levels of Sirt3 induces a switch of skeletal muscle substrate utilization from carbohydrate oxidation toward lactate production and fatty acid utilization even in the fed state, contributing to a loss of metabolic flexibility. Thus, Sirt3 plays an important role in skeletal muscle mitochondrial substrate choice and metabolic flexibility in part by regulating PDH function through deacetylation.
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Affiliation(s)
- Enxuan Jing
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Brian T. O’Neill
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | | | - André Kleinridders
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Olga R. Ilkeyeva
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Siegfried Ussar
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - James R. Bain
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Kevin Y. Lee
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Eric M. Verdin
- Gladstone Institute of Virology and Immunology, San Francisco, California
- Department of Medicine, University of California, San Francisco, San Francisco, California
| | | | | | - C. Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
- Corresponding author: C. Ronald Kahn,
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134
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Kang HW, Ozdemir C, Kawano Y, LeClair KB, Vernochet C, Kahn CR, Hagen SJ, Cohen DE. Thioesterase superfamily member 2/Acyl-CoA thioesterase 13 (Them2/Acot13) regulates adaptive thermogenesis in mice. J Biol Chem 2013; 288:33376-86. [PMID: 24072708 DOI: 10.1074/jbc.m113.481408] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the acyl-CoA thioesterase (Acot) gene family hydrolyze fatty acyl-CoAs, but their biological functions remain incompletely understood. Thioesterase superfamily member 2 (Them2; synonym Acot13) is enriched in oxidative tissues, associated with mitochondria, and relatively specific for long chain fatty acyl-CoA substrates. Using Them2(-/-) mice, we have demonstrated key roles for Them2 in regulating hepatic glucose and lipid metabolism. However, reduced body weights and decreased adiposity in Them2(-/-) mice observed despite increased food consumption were not well explained. To explore a role in thermogenesis, mice were exposed to ambient temperatures ranging from thermoneutrality (30 °C) to cold (4 °C). In response to short term (24-h) exposures to decreasing ambient temperatures, Them2(-/-) mice exhibited increased adaptive responses in physical activity, food consumption, and energy expenditure when compared with Them2(+/+) mice. By contrast, genotype-dependent differences were not observed in mice that were equilibrated (96 h) at each ambient temperature. In brown adipose tissue, the absence of Them2 was associated with reduced lipid droplets, alterations in the ultrastructure of mitochondria, and increased expression of thermogenic genes. Indicative of a direct regulatory role for Them2 in heat production, cultured primary brown adipocytes from Them2(-/-) mice exhibited increased norepinephrine-mediated triglyceride hydrolysis and increased rates of O2 consumption, together with elevated expression of thermogenic genes. At least in part by regulating intracellular fatty acid channeling, Them2 functions in brown adipose tissue to suppress adaptive increases in energy expenditure.
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Affiliation(s)
- Hye Won Kang
- From the Department of Medicine, Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
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135
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Chen YCI, Cypess AM, Chen YC, Palmer M, Kolodny G, Kahn CR, Kwong KK. Measurement of human brown adipose tissue volume and activity using anatomic MR imaging and functional MR imaging. J Nucl Med 2013; 54:1584-7. [PMID: 23868958 DOI: 10.2967/jnumed.112.117275] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
UNLABELLED The aim of this study was to assess the volume and function of human brown adipose tissue (BAT) in vivo using MR imaging. METHODS BAT volumes under thermoneutral conditions in the cervical areas were assessed via water-fat contrast using the Dixon method and via water-saturation efficiency using fast spin-echo and T2-weighted images. The existence of cervical BAT was also assessed by (18)F-FDG PET/CT scans in the same subjects. BAT functionality was assessed via functional MR imaging (fMRI) blood oxygenation level-dependent (BOLD) signal changes in response to a mild cold challenge. RESULTS Under thermoneutral conditions, we were able to distinguish BAT from white adipose tissue in the cervical and supraclavicular fat. BAT showed higher water-to-fat contrast and higher water-saturation efficiency in MR imaging scans. The location and volume of BAT assessed by MR imaging were comparable to the measurements by (18)F-FDG PET/CT scans. During mild cold challenge, BOLD fMRI signal increased in BAT by 10.7% ± 1.8% (P < 0.01). CONCLUSION We demonstrated the feasibility of using MR imaging and fMRI to assess BAT volume and BAT responses to mild cold stimulation in the cervical areas of human subjects.
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Affiliation(s)
- Yin-Ching Iris Chen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
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136
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Chudasama KK, Winnay J, Johansson S, Claudi T, König R, Haldorsen I, Johansson B, Woo JR, Aarskog D, Sagen JV, Kahn CR, Molven A, Njølstad PR. SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling. Am J Hum Genet 2013; 93:150-7. [PMID: 23810379 DOI: 10.1016/j.ajhg.2013.05.023] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/18/2013] [Accepted: 05/24/2013] [Indexed: 01/19/2023] Open
Abstract
The phosphatidylinositol 3 kinase (PI3K) pathway regulates fundamental cellular processes such as metabolism, proliferation, and survival. A central component in this pathway is the p85α regulatory subunit, encoded by PIK3R1. Using whole-exome sequencing, we identified a heterozygous PIK3R1 mutation (c.1945C>T [p.Arg649Trp]) in two unrelated families affected by partial lipodystrophy, low body mass index, short stature, progeroid face, and Rieger anomaly (SHORT syndrome). This mutation led to impaired interaction between p85α and IRS-1 and reduced AKT-mediated insulin signaling in fibroblasts from affected subjects and in reconstituted Pik3r1-knockout preadipocytes. Normal PI3K activity is critical for adipose differentiation and insulin signaling; the mutated PIK3R1 therefore provides a unique link among lipodystrophy, growth, and insulin signaling.
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Affiliation(s)
- Kishan Kumar Chudasama
- K.G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020 Bergen, Norway
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137
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Gahete MD, Córdoba-Chacón J, Lin Q, Brüning JC, Kahn CR, Castaño JP, Christian H, Luque RM, Kineman RD. Insulin and IGF-I inhibit GH synthesis and release in vitro and in vivo by separate mechanisms. Endocrinology 2013; 154:2410-20. [PMID: 23671263 PMCID: PMC3689283 DOI: 10.1210/en.2013-1261] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
IGF-I is considered a primary inhibitor of GH secretion. Insulin may also play an important role in regulating GH levels because insulin, like IGF-I, can suppress GH synthesis and release in primary pituitary cell cultures and insulin is negatively correlated with GH levels in vivo. However, understanding the relative contribution insulin and IGF-I exert on controlling GH secretion has been hampered by the fact that circulating insulin and IGF-I are regulated in parallel and insulin (INSR) and IGF-I (IGFIR) receptors are structurally/functionally related and ubiquitously expressed. To evaluate the separate roles of insulin and IGF-I in directly regulating GH secretion, we used the Cre/loxP system to knock down the INSR and IGFIR in primary mouse pituitary cell cultures and found insulin-mediated suppression of GH is independent of the IGFIR. In addition, pharmacological blockade of intracellular signals in both mouse and baboon cultures revealed insulin requires different pathways from IGF-I to exert a maximal inhibitory effect on GH expression/release. In vivo, somatotrope-specific knockout of INSR (SIRKO) or IGFIR (SIGFRKO) increased GH levels. However, comparison of the pattern of GH release, GH expression, somatotrope morphometry, and pituitary explant sensitivity to acute GHRH challenge in lean SIRKO and SIGFRKO mice strongly suggests the primary role of insulin in vivo is to suppress GH release, whereas IGF-I serves to regulate GH synthesis. Finally, SIRKO and/or SIGFRKO could not prevent high-fat, diet-induced suppression of pituitary GH expression, indicating other factors/tissues are involved in the decline of GH observed with weight gain.
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Affiliation(s)
- Manuel D Gahete
- Research and Development Division, Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
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138
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Bagchi M, Kim LA, Boucher J, Walshe TE, Kahn CR, D'Amore PA. Vascular endothelial growth factor is important for brown adipose tissue development and maintenance. FASEB J 2013; 27:3257-71. [PMID: 23682123 DOI: 10.1096/fj.12-221812] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Vascular endothelial growth factor (VEGF) is critical for angiogenesis, but also has pleiotropic effects on several nonvascular cells. Our aim was to investigate the role of VEGF in brown adipose tissue (BAT). We show that VEGF expression increases 2.5-fold during differentiation of cultured murine brown adipocytes and that VEGF receptor-2 is phosphorylated, indicating VEGF signaling. VEGF increased proliferation in brown preadipocytes in vitro by 70%, and blockade of VEGF signaling using anti-VEGFR2 antibody DC101 increased brown adipocyte apoptosis, as determined by cell number and activation of caspase 3. Systemic VEGF neutralization in mice, accomplished by adenoviral expression of soluble Flt1, resulted in 7-fold increase in brown adipocyte apoptosis, mitochondrial degeneration, and increased mitophagy compared to control mice expressing a null adenovirus. Absence of the heparan sulfate-binding VEGF isoforms, VEGF164 and VEGF188, resulted in abnormal BAT development in mice at E15.5, with fewer brown adipocytes and lower mitochondrial protein compared to wild-type littermates. These results suggest a role for VEGF in brown adipocytes and preadipocytes to promote survival, proliferation, and normal mitochondria and development.
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Affiliation(s)
- Mandrita Bagchi
- Department of Pathology, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
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139
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Ræder H, Vesterhus M, El Ouaamari A, Paulo JA, McAllister FE, Liew CW, Hu J, Kawamori D, Molven A, Gygi SP, Njølstad PR, Kahn CR, Kulkarni RN. Absence of diabetes and pancreatic exocrine dysfunction in a transgenic model of carboxyl-ester lipase-MODY (maturity-onset diabetes of the young). PLoS One 2013; 8:e60229. [PMID: 23565203 PMCID: PMC3615023 DOI: 10.1371/journal.pone.0060229] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/23/2013] [Indexed: 01/04/2023] Open
Abstract
Background CEL-MODY is a monogenic form of diabetes with exocrine pancreatic insufficiency caused by mutations in CARBOXYL-ESTER LIPASE (CEL). The pathogenic processes underlying CEL-MODY are poorly understood, and the global knockout mouse model of the CEL gene (CELKO) did not recapitulate the disease. We therefore aimed to create and phenotype a mouse model specifically over-expressing mutated CEL in the pancreas. Methods We established a monotransgenic floxed (flanking LOX sequences) mouse line carrying the human CEL mutation c.1686delT and crossed it with an elastase-Cre mouse to derive a bitransgenic mouse line with pancreas-specific over-expression of CEL carrying this disease-associated mutation (TgCEL). Following confirmation of murine pancreatic expression of the human transgene by real-time quantitative PCR, we phenotyped the mouse model fed a normal chow and compared it with mice fed a 60% high fat diet (HFD) as well as the effects of short-term and long-term cerulein exposure. Results Pancreatic exocrine function was normal in TgCEL mice on normal chow as assessed by serum lipid and lipid-soluble vitamin levels, fecal elastase and fecal fat absorption, and the normoglycemic mice exhibited normal pancreatic morphology. On 60% HFD, the mice gained weight to the same extent as controls, had normal pancreatic exocrine function and comparable glucose tolerance even after resuming normal diet and follow up up to 22 months of age. The cerulein-exposed TgCEL mice gained weight and remained glucose tolerant, and there were no detectable mutation-specific differences in serum amylase, islet hormones or the extent of pancreatic tissue inflammation. Conclusions In this murine model of human CEL-MODY diabetes, we did not detect mutation-specific endocrine or exocrine pancreatic phenotypes, in response to altered diets or exposure to cerulein.
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Affiliation(s)
- Helge Ræder
- Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, United States of America.
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140
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Lee KY, Russell SJ, Ussar S, Boucher J, Vernochet C, Mori MA, Smyth G, Rourk M, Cederquist C, Rosen ED, Kahn BB, Kahn CR. Lessons on conditional gene targeting in mouse adipose tissue. Diabetes 2013; 62:864-74. [PMID: 23321074 PMCID: PMC3581196 DOI: 10.2337/db12-1089] [Citation(s) in RCA: 271] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Conditional gene targeting has been extensively used for in vivo analysis of gene function in adipocyte cell biology but often with debate over the tissue specificity and the efficacy of inactivation. To directly compare the specificity and efficacy of different Cre lines in mediating adipocyte specific recombination, transgenic Cre lines driven by the adipocyte protein 2 (aP2) and adiponectin (Adipoq) gene promoters, as well as a tamoxifen-inducible Cre driven by the aP2 gene promoter (iaP2), were bred to the Rosa26R (R26R) reporter. All three Cre lines demonstrated recombination in the brown and white fat pads. Using different floxed loci, the individual Cre lines displayed a range of efficacy to Cre-mediated recombination that ranged from no observable recombination to complete recombination within the fat. The Adipoq-Cre exhibited no observable recombination in any other tissues examined, whereas both aP2-Cre lines resulted in recombination in endothelial cells of the heart and nonendothelial, nonmyocyte cells in the skeletal muscle. In addition, the aP2-Cre line can lead to germline recombination of floxed alleles in ~2% of spermatozoa. Thus, different "adipocyte-specific" Cre lines display different degrees of efficiency and specificity, illustrating important differences that must be taken into account in their use for studying adipose biology.
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Affiliation(s)
- Kevin Y. Lee
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Steven J. Russell
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Siegfried Ussar
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Jeremie Boucher
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Cecile Vernochet
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Marcelo A. Mori
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Graham Smyth
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Michael Rourk
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Carly Cederquist
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - Evan D. Rosen
- Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Barbara B. Kahn
- Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - C. Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
- Corresponding author: C. Ronald Kahn,
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141
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Abstract
Developmental genes are essential in the formation and function of adipose tissue and muscle. In this issue of Cell, Teperino et al. demonstrate that noncanonical hedgehog signaling increases glucose uptake into brown fat and muscle. Modulation of developmental pathways may serve as a potential target for new treatments of diabetes and other metabolic disorders.
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Affiliation(s)
- Kevin Y Lee
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02115, USA
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142
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Vernochet C, Mourier A, Bezy O, Macotela Y, Boucher J, Rardin MJ, An D, Lee KY, Ilkayeva OR, Zingaretti CM, Emanuelli B, Smyth G, Cinti S, Newgard CB, Gibson BW, Larsson NG, Kahn CR. Adipose-specific deletion of TFAM increases mitochondrial oxidation and protects mice against obesity and insulin resistance. Cell Metab 2012; 16:765-76. [PMID: 23168219 PMCID: PMC3529641 DOI: 10.1016/j.cmet.2012.10.016] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 08/08/2012] [Accepted: 10/25/2012] [Indexed: 01/01/2023]
Abstract
Obesity and type 2 diabetes are associated with mitochondrial dysfunction in adipose tissue, but the role for adipose tissue mitochondria in the development of these disorders is currently unknown. To understand the impact of adipose tissue mitochondria on whole-body metabolism, we have generated a mouse model with disruption of the mitochondrial transcription factor A (TFAM) specifically in fat. F-TFKO adipose tissue exhibit decreased mtDNA copy number, altered levels of proteins of the electron transport chain, and perturbed mitochondrial function with decreased complex I activity and greater oxygen consumption and uncoupling. As a result, F-TFKO mice exhibit higher energy expenditure and are protected from age- and diet-induced obesity, insulin resistance, and hepatosteatosis, despite a greater food intake. Thus, TFAM deletion in the adipose tissue increases mitochondrial oxidation that has positive metabolic effects, suggesting that regulation of adipose tissue mitochondria may be a potential therapeutic target for the treatment of obesity.
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Affiliation(s)
- Cecile Vernochet
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Arnaud Mourier
- Max Planck Institute for Biology of Ageing, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Olivier Bezy
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
- Pfizer, Inc, Cardiovascular Metabolic and Endocrine Diseases (CVMED), 620 Memorial Drive, Cambridge, MA 02139
| | - Yazmin Macotela
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, 76230 Querétaro, Mexico
| | - Jeremie Boucher
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Matthew J. Rardin
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Ding An
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Kevin Y. Lee
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Olga R. Ilkayeva
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27704, USA
| | - Cristina M. Zingaretti
- Department Experimental and Clinical Medicine-Diagnostic Electron Microscopy Unit University-United Hospitals of Ancona, Ancona 60020 & Adipose Organ Lab IRCCS San Raffaele Pisana, Rome 00163, Italy
| | - Brice Emanuelli
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Graham Smyth
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
| | - Saverio Cinti
- Department Experimental and Clinical Medicine-Diagnostic Electron Microscopy Unit University-United Hospitals of Ancona, Ancona 60020 & Adipose Organ Lab IRCCS San Raffaele Pisana, Rome 00163, Italy
| | - Christopher B. Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27704, USA
| | - Bradford W. Gibson
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Nils-Göran Larsson
- Max Planck Institute for Biology of Ageing, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - C. Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA
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143
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144
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Abstract
Impaired insulin signaling is central to development of the metabolic syndrome and can promote cardiovascular disease indirectly through development of abnormal glucose and lipid metabolism, hypertension, and a proinflammatory state. However, insulin's action directly on vascular endothelium, atherosclerotic plaque macrophages, and in the heart, kidney, and retina has now been described, and impaired insulin signaling in these locations can alter progression of cardiovascular disease in the metabolic syndrome and affect development of microvascular complications of diabetes mellitus. Recent advances in our understanding of the complex pathophysiology of insulin's effects on vascular tissues offer new opportunities for preventing these cardiovascular disorders.
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Affiliation(s)
- Christian Rask-Madsen
- Joslin Diabetes Center, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
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145
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Abstract
Glucocorticoids are a powerful tool used to treat a range of human illnesses, including autoimmune diseases and cancer, and to prevent rejection following organ transplantation. While lifesaving for many, they come with a steep price, often leading to obesity, insulin resistance, diabetes, and osteoporosis. In this issue of the JCI, Brennan-Speranza and colleagues provide evidence that the osteoblast-derived peptide osteocalcin is one of the drivers of the metabolic derangements associated with glucocorticoid therapy. This novel mechanism could open up new avenues for the treatment of these disorders.
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Affiliation(s)
- Heather A Ferris
- Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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146
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Mori MA, Raghavan P, Thomou T, Boucher J, Robida-Stubbs S, Macotela Y, Russell SJ, Kirkland JL, Blackwell TK, Kahn CR. Role of microRNA processing in adipose tissue in stress defense and longevity. Cell Metab 2012; 16:336-47. [PMID: 22958919 PMCID: PMC3461823 DOI: 10.1016/j.cmet.2012.07.017] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 06/14/2012] [Accepted: 07/12/2012] [Indexed: 12/21/2022]
Abstract
Excess adipose tissue is associated with metabolic disease and reduced life span, whereas caloric restriction decreases these risks. Here we show that as mice age, there is downregulation of Dicer and miRNA processing in adipose tissue resulting in decreases of multiple miRNAs. A similar decline of Dicer with age is observed in C. elegans. This is prevented in both species by caloric restriction. Decreased Dicer expression also occurs in preadipocytes from elderly humans and can be produced in cells by exposure to oxidative stress or UV radiation. Knockdown of Dicer in cells results in premature senescence, and fat-specific Dicer knockout renders mice hypersensitive to oxidative stress. Finally, Dicer loss-of-function mutations in worms reduce life span and stress tolerance, while intestinal overexpression of Dicer confers stress resistance. Thus, regulation of miRNA processing in adipose-related tissues plays an important role in longevity and the ability of an organism to respond to environmental stress and age-related disease.
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Affiliation(s)
- Marcelo A Mori
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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147
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Ussar S, Bezy O, Blüher M, Kahn CR. Glypican-4 enhances insulin signaling via interaction with the insulin receptor and serves as a novel adipokine. Diabetes 2012; 61:2289-98. [PMID: 22751693 PMCID: PMC3425403 DOI: 10.2337/db11-1395] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 03/26/2012] [Indexed: 11/13/2022]
Abstract
Obesity, especially visceral obesity, is associated with insulin resistance and metabolic syndrome. We previously identified the cell surface proteoglycan glypican-4 as differentially expressed in subcutaneous versus visceral white fat depots. Here we show that glypican-4 is released from cells and adipose tissue explants of mice, and that circulating glypican-4 levels correlate with BMI and insulin sensitivity in humans. Furthermore, glypican-4 interacts with the insulin receptor, enhances insulin receptor signaling, and enhances adipocyte differentiation. Conversely, depletion of glypican-4 results in reduced activation of the insulin receptor and prevents adipocyte differentiation in vitro by inhibiting insulin-mediated C/EBPβ phosphorylation. These functions of glypican-4 are independent of its glycosylphosphatidylinositol membrane anchorage, as a nonmembrane-bound mutant of glypican-4 phenocopies the effects of native glypican-4 overexpression. In summary, glypican-4 is a novel circulating insulin sensitizing adipose-derived factor that, unlike other insulin sensitizers, acts directly on the insulin receptor to enhance signaling.
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Affiliation(s)
- Siegfried Ussar
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - Olivier Bezy
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - Matthias Blüher
- Department of Medicine, University of Leipzig, Leipzig, Germany
| | - C. Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
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148
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Abstract
Obesity and body fat distribution are important risk factors for the development of type 2 diabetes and metabolic syndrome. Evidence has accumulated that this risk is related to intrinsic differences in behavior of adipocytes in different fat depots. In the current study, we demonstrate that adipocyte precursor cells (APCs) isolated from visceral and subcutaneous white adipose depots of mice have distinct patterns of gene expression, differentiation potential, and response to environmental and genetic influences. APCs derived from subcutaneous fat differentiate well in the presence of classical induction cocktail, whereas those from visceral fat differentiate poorly but can be induced to differentiate by addition of bone morphogenetic protein (BMP)-2 or BMP-4. This difference correlates with major differences in gene expression signature between subcutaneous and visceral APCs. The number of APCs is higher in obesity-prone C57BL/6 mice than obesity-resistant 129 mice, and the number in both depots is increased by up to 270% by exposure of mice to high-fat diet. Thus, APCs from visceral and subcutaneous depots are dynamic populations, which have intrinsic differences in gene expression, differentiation properties, and responses to environmental/genetic factors. Regulation of these populations may provide a new target for the treatment and prevention of obesity and its metabolic complications.
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149
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Chen YI, Cypess AM, Sass CA, Brownell AL, Jokivarsi KT, Kahn CR, Kwong KK. Anatomical and functional assessment of brown adipose tissue by magnetic resonance imaging. Obesity (Silver Spring) 2012; 20:1519-26. [PMID: 22343821 PMCID: PMC4383098 DOI: 10.1038/oby.2012.22] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Brown adipose tissue (BAT) is the primary tissue responsible for nonshivering thermogenesis in mammals. The amount of BAT and its level of activation help regulate the utilization of excessive calories for thermogenesis as opposed to storage in white adipose tissue (WAT) which would lead to weight gain. Over the past several years, BAT activity in vivo has been primarily assessed by positron emission tomography-computed tomography (PET-CT) scan using 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) to measure glucose utilization associated with BAT mitochondrial respiration. In this study, we demonstrate the feasibility of mapping and estimating BAT volume and metabolic function in vivo in rats at a 9.4T magnetic resonance imaging (MRI) scanner using sequences available from clinical MR scanners. Based on the morphological characteristics of BAT, we measured the volume distribution of BAT with MRI sequences that have strong fat-water contrast. We also investigated BAT volume by utilizing spin-echo MRI sequences. The in vivo MRI-estimated BAT volumes were correlated with direct measurement of BAT mass from dissected samples. Using MRI, we also were able to map hemodynamic responses to changes in BAT metabolism induced pharmacologically by β3-adrenergic receptor agonist, CL-316,243 and compare this to BAT activity in response to CL-316,243 assessed by PET 18F-FDG. In conclusion, we demonstrate the feasibility of measuring BAT volume and function in vivo using routine MRI sequences. The MRI measurement of BAT volume is consistent with quantitative measurement of the tissue ex vivo.
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Affiliation(s)
- Y Iris Chen
- A. Martino's Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA.
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150
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Boucher J, Mori MA, Lee KY, Smyth G, Liew CW, Macotela Y, Rourk M, Bluher M, Russell SJ, Kahn CR. Impaired thermogenesis and adipose tissue development in mice with fat-specific disruption of insulin and IGF-1 signalling. Nat Commun 2012; 3:902. [PMID: 22692545 PMCID: PMC3529640 DOI: 10.1038/ncomms1905] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 05/14/2012] [Indexed: 12/31/2022] Open
Abstract
Insulin and insulin-like growth factor 1 (IGF-1) have important roles in adipocyte differentiation, glucose tolerance and insulin sensitivity. Here to assess how these pathways can compensate for each other, we created mice with a double tissue-specific knockout of insulin and IGF-1 receptors to eliminate all insulin/IGF-1 signalling in fat. These FIGIRKO mice had markedly decreased white and brown fat mass and were completely resistant to high fat diet-induced obesity and age- and high fat diet-induced glucose intolerance. Energy expenditure was increased in FIGIRKO mice despite a >85% reduction in brown fat mass. However, FIGIRKO mice were unable to maintain body temperature when placed at 4 °C. Brown fat activity was markedly decreased in FIGIRKO mice but was responsive to β3-receptor stimulation. Thus, insulin/IGF-1 signalling has a crucial role in the control of brown and white fat development, and, when disrupted, leads to defective thermogenesis and a paradoxical increase in basal metabolic rate.
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Affiliation(s)
- Jeremie Boucher
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA
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