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Saneyasu T. Recent Research on Mechanisms of Feeding Regulation in Chicks. J Poult Sci 2024; 61:2024012. [PMID: 38681189 PMCID: PMC11039390 DOI: 10.2141/jpsa.2024012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 04/02/2024] [Indexed: 05/01/2024] Open
Abstract
Food intake affects poultry productivity. A complete understanding of these regulatory mechanisms provides new strategies to improve productivity. Food intake is regulated by complex mechanisms involving many factors, including the central nervous system, gastrointestinal tract, hormones, and nutrients. Although several studies have been conducted to elucidate regulatory mechanisms in chickens, the mechanisms remain unclear. To update the current knowledge on feeding regulation in chickens, this review focuses on recent findings that have not been summarized in previous reviews, including spexins, adipokines, neurosecretory proteins GL and GM, and central intracellular signaling factors.
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Affiliation(s)
- Takaoki Saneyasu
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501,
Japan
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2
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Metaxakis A, Pavlidis M, Tavernarakis N. Neuronal atg1 Coordinates Autophagy Induction and Physiological Adaptations to Balance mTORC1 Signalling. Cells 2023; 12:2024. [PMID: 37626835 PMCID: PMC10453232 DOI: 10.3390/cells12162024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/04/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
The mTORC1 nutrient-sensing pathway integrates metabolic and endocrine signals into the brain to evoke physiological responses to food deprivation, such as autophagy. Nevertheless, the impact of neuronal mTORC1 activity on neuronal circuits and organismal metabolism remains obscure. Here, we show that mTORC1 inhibition acutely perturbs serotonergic neurotransmission via proteostatic alterations evoked by the autophagy inducer atg1. Neuronal ATG1 alters the intracellular localization of the serotonin transporter, which increases the extracellular serotonin and stimulates the 5HTR7 postsynaptic receptor. 5HTR7 enhances food-searching behaviour and ecdysone-induced catabolism in Drosophila. Along similar lines, the pharmacological inhibition of mTORC1 in zebrafish also stimulates food-searching behaviour via serotonergic activity. These effects occur in parallel with neuronal autophagy induction, irrespective of the autophagic activity and the protein synthesis reduction. In addition, ectopic neuronal atg1 expression enhances catabolism via insulin pathway downregulation, impedes peptidergic secretion, and activates non-cell autonomous cAMP/PKA. The above exert diverse systemic effects on organismal metabolism, development, melanisation, and longevity. We conclude that neuronal atg1 aligns neuronal autophagy induction with distinct physiological modulations, to orchestrate a coordinated physiological response against reduced mTORC1 activity.
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Affiliation(s)
- Athanasios Metaxakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Nikolaou Plastira 100, 70013 Heraklion, Crete, Greece
| | - Michail Pavlidis
- Department of Biology, University of Crete, 71409 Heraklion, Crete, Greece;
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Nikolaou Plastira 100, 70013 Heraklion, Crete, Greece
- Department of Basic Sciences, Faculty of Medicine, University of Crete, 71110 Heraklion, Crete, Greece
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3
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Oleinika K, Slisere B, Catalán D, Rosser EC. B cell contribution to immunometabolic dysfunction and impaired immune responses in obesity. Clin Exp Immunol 2022; 210:263-272. [PMID: 35960996 PMCID: PMC9384752 DOI: 10.1093/cei/uxac079] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/15/2022] [Accepted: 08/09/2022] [Indexed: 11/14/2022] Open
Abstract
Obesity increases the risk of type 2 diabetes mellitus, cardiovascular disease, fatty liver disease, and cancer. It is also linked with more severe complications from infections, including COVID-19, and poor vaccine responses. Chronic, low-grade inflammation and associated immune perturbations play an important role in determining morbidity in people living with obesity. The contribution of B cells to immune dysregulation and meta-inflammation associated with obesity has been documented by studies over the past decade. With a focus on human studies, here we consolidate the observations demonstrating that there is altered B cell subset composition, differentiation, and function both systemically and in the adipose tissue of individuals living with obesity. Finally, we discuss the potential factors that drive B cell dysfunction in obesity and propose a model by which altered B cell subset composition in obesity underlies dysfunctional B cell responses to novel pathogens.
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Affiliation(s)
- Kristine Oleinika
- Correspondence: Kristine Oleinika, Department of Internal Diseases, Riga Stradins University, Riga, Latvia.
| | - Baiba Slisere
- Department of Doctoral Studies, Riga Stradins University, Riga, Latvia
- Joint Laboratory, Pauls Stradins Clinical University Hospital, Riga, Latvia
| | - Diego Catalán
- Programa Disciplinario de Inmunología, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Elizabeth C Rosser
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH and GOSH and Department of Rheumatology, Division of Medicine, University College London, London, UK
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4
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Abstract
The mechanistic target of the rapamycin (mTOR) signaling pathway is the central regulator of cell growth and proliferation by integrating growth factor and nutrient availability. Under healthy physiological conditions, this process is tightly coordinated and essential to maintain whole-body homeostasis. Not surprisingly, dysregulated mTOR signaling underpins several diseases with increasing incidence worldwide, including obesity, diabetes, and cancer. Consequently, there is significant clinical interest in developing therapeutic strategies that effectively target this pathway. The transition of mTOR inhibitors from the bench to bedside, however, has largely been marked with challenges and shortcomings, such as the development of therapy resistance and adverse side effects in patients. In this review, we discuss the current status of first-, second-, and third-generation mTOR inhibitors as a cancer therapy in both preclinical and clinical settings, with a particular emphasis on the mechanisms of drug resistance. We focus especially on the emerging role of diet as an important environmental determinant of therapy response, and posit a conceptual framework that links nutrient availability and whole-body metabolic states such as obesity with many of the previously defined processes that drive resistance to mTOR-targeted therapies. Given the role of mTOR as a central integrator of cell metabolism and function, we propose that modulating nutrient inputs through dietary interventions may influence the signaling dynamics of this pathway and compensatory nodes. In doing so, new opportunities for exploiting diet/drug synergies are highlighted that may unlock the therapeutic potential of mTOR inhibitors as a cancer treatment.
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Affiliation(s)
- Nikos Koundouros
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10021,USA
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10021, USA
- Correspondence: Nikos Koundouros, Meyer Cancer Center, Weill Cornell Medicine, 413 East 69th Street, New York, NY, 10021 USA.
| | - John Blenis
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10021,USA
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10021, USA
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10021, USA
- Correspondence: John Blenis, Meyer Cancer Center, Weill Cornell Medicine, 413 East 69th Street, New York, NY, 10021 USA.
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5
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Oestrogen engages brain MC4R signalling to drive physical activity in female mice. Nature 2021; 599:131-135. [PMID: 34646010 PMCID: PMC9113400 DOI: 10.1038/s41586-021-04010-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 09/09/2021] [Indexed: 12/30/2022]
Abstract
Oestrogen depletion in rodents and humans leads to inactivity, fat accumulation and diabetes1,2, underscoring the conserved metabolic benefits of oestrogen that inevitably decrease with age. In rodents, the preovulatory surge in 17β-oestradiol (E2) temporarily increases energy expenditure to coordinate increased physical activity with peak sexual receptivity. Here we report that a subset of oestrogen-sensitive neurons in the ventrolateral ventromedial hypothalamic nucleus (VMHvl)3-7 projects to arousal centres in the hippocampus and hindbrain, and enables oestrogen to rebalance energy allocation in female mice. Surges in E2 increase melanocortin-4 receptor (MC4R) signalling in these VMHvl neurons by directly recruiting oestrogen receptor-α (ERα) to the Mc4r gene. Sedentary behaviour and obesity in oestrogen-depleted female mice were reversed after chemogenetic stimulation of VMHvl neurons expressing both MC4R and ERα. Similarly, a long-term increase in physical activity is observed after CRISPR-mediated activation of this node. These data extend the effect of MC4R signalling - the most common cause of monogenic human obesity8 - beyond the regulation of food intake and rationalize reported sex differences in melanocortin signalling, including greater disease severity of MC4R insufficiency in women9. This hormone-dependent node illuminates the power of oestrogen during the reproductive cycle in motivating behaviour and maintaining an active lifestyle in women.
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6
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Mathur N, Mehdi SF, Anipindi M, Aziz M, Khan SA, Kondakindi H, Lowell B, Wang P, Roth J. Ghrelin as an Anti-Sepsis Peptide: Review. Front Immunol 2021; 11:610363. [PMID: 33584688 PMCID: PMC7876230 DOI: 10.3389/fimmu.2020.610363] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/09/2020] [Indexed: 12/15/2022] Open
Abstract
Sepsis continues to produce widespread inflammation, illness, and death, prompting intensive research aimed at uncovering causes and therapies. In this article, we focus on ghrelin, an endogenous peptide with promise as a potent anti-inflammatory agent. Ghrelin was discovered, tracked, and isolated from stomach cells based on its ability to stimulate release of growth hormone. It also stimulates appetite and is shown to be anti-inflammatory in a wide range of tissues. The anti-inflammatory effects mediated by ghrelin are a result of both the stimulation of anti-inflammatory processes and an inhibition of pro-inflammatory forces. Anti-inflammatory processes are promoted in a broad range of tissues including the hypothalamus and vagus nerve as well as in a broad range of immune cells. Aged rodents have reduced levels of growth hormone (GH) and diminished immune responses; ghrelin administration boosts GH levels and immune response. The anti-inflammatory functions of ghrelin, well displayed in preclinical animal models of sepsis, are just being charted in patients, with expectations that ghrelin and growth hormone might improve outcomes in patients with sepsis.
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Affiliation(s)
- Nimisha Mathur
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Syed F. Mehdi
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Manasa Anipindi
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Monowar Aziz
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
- Center for Immunology and Inflammation, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Sawleha A. Khan
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Hema Kondakindi
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Barbara Lowell
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Ping Wang
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
- Center for Immunology and Inflammation, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Jesse Roth
- Laboratory of Diabetes, Obesity, and Other Metabolic Disorders, The Feinstein Institutes for Medical Research, Manhasset, NY, United States
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7
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Methylation of Hypothalamic Tsc1-mTOR Signaling in Regulation of Obesity and Obesity Resistance. BIOMED RESEARCH INTERNATIONAL 2020; 2020:8723869. [PMID: 33532487 PMCID: PMC7836023 DOI: 10.1155/2020/8723869] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 11/10/2020] [Accepted: 12/20/2020] [Indexed: 02/05/2023]
Abstract
The Tsc1-mTOR signaling pathway is often related to obesity, and epigenetic modification may lead to expression changes of obesity-related gene. Therefore, we aim to investigate the methylation of the Tsc1-mTOR signaling pathway in regulation of obesity susceptibility. Wistar rats were fed a normal diet or a high-fat diet to develop animal models. Protein and mRNA expression levels of Tsc1-mTOR signaling in the hypothalamus were determined by Western blot and quantitative real-time PCR. Methylation of Tsc1 gene promoter was detected by bisulfite genomic sequence. Both mRNA and protein expression levels of Tsc1 in DIO group hypothalamus were lower; mTOR and its downstream targets S6K1, 4EBP1, and S6 protein expression levels were higher than those of the DIO-R group and the chow group. The Tsc1 gene promoter methylation rate in the hypothalamus was 92.05 ± 3.07% in the DIO group, 87.27 ± 1.91% in the DIO-R group, and 88.18% ± 3.20% in the chow group, respectively, with significantly higher levels in the DIO group. Both the expression levels of Tsc1 gene promoter methylation and Tsc1-mTOR signaling pathway in the hypothalamus of DIO rats and DIO-R rats are different. These findings may shed light on the potential mechanism for the differentiation of obesity susceptibility.
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8
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Damiano S, Sozio C, La Rosa G, Guida B, Faraonio R, Santillo M, Mondola P. Metabolism Regulation and Redox State: Insight into the Role of Superoxide Dismutase 1. Int J Mol Sci 2020; 21:ijms21186606. [PMID: 32927603 PMCID: PMC7554782 DOI: 10.3390/ijms21186606] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/31/2020] [Accepted: 09/08/2020] [Indexed: 12/14/2022] Open
Abstract
Energy metabolism and redox state are strictly linked; energy metabolism is a source of reactive oxygen species (ROS) that, in turn, regulate the flux of metabolic pathways. Moreover, to assure redox homeostasis, metabolic pathways and antioxidant systems are often coordinately regulated. Several findings show that superoxide dismutase 1 (SOD1) enzyme has effects that go beyond its superoxide dismutase activity and that its functions are not limited to the intracellular compartment. Indeed, SOD1 is secreted through unconventional secretory pathways, carries out paracrine functions and circulates in the blood bound to lipoproteins. Striking experimental evidence links SOD1 to the redox regulation of metabolism. Important clues are provided by the systemic effects on energy metabolism observed in mutant SOD1-mediated amyotrophic lateral sclerosis (ALS). The purpose of this review is to analyze in detail the involvement of SOD1 in redox regulation of metabolism, nutrient sensing, cholesterol metabolism and regulation of mitochondrial respiration. The scientific literature on the relationship between ALS, mutated SOD1 and metabolism will also be explored, in order to highlight the metabolic functions of SOD1 whose biological role still presents numerous unexplored aspects that deserve further investigation.
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Affiliation(s)
- Simona Damiano
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli “Federico II”, 80131 Naples, Italy; (S.D.); (C.S.); (G.L.R.); (B.G.)
| | - Concetta Sozio
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli “Federico II”, 80131 Naples, Italy; (S.D.); (C.S.); (G.L.R.); (B.G.)
| | - Giuliana La Rosa
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli “Federico II”, 80131 Naples, Italy; (S.D.); (C.S.); (G.L.R.); (B.G.)
| | - Bruna Guida
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli “Federico II”, 80131 Naples, Italy; (S.D.); (C.S.); (G.L.R.); (B.G.)
| | - Raffaella Faraonio
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli “Federico II”, 80131 Naples, Italy;
| | - Mariarosaria Santillo
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli “Federico II”, 80131 Naples, Italy; (S.D.); (C.S.); (G.L.R.); (B.G.)
- Correspondence: (M.S.); (P.M.); Tel.: +39-081-746-3233 (M.S.); +39-081-746-3225 (P.M.)
| | - Paolo Mondola
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli “Federico II”, 80131 Naples, Italy; (S.D.); (C.S.); (G.L.R.); (B.G.)
- Correspondence: (M.S.); (P.M.); Tel.: +39-081-746-3233 (M.S.); +39-081-746-3225 (P.M.)
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9
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Pena-Leon V, Perez-Lois R, Seoane LM. mTOR Pathway is Involved in Energy Homeostasis Regulation as a Part of the Gut-Brain Axis. Int J Mol Sci 2020; 21:ijms21165715. [PMID: 32784967 PMCID: PMC7460813 DOI: 10.3390/ijms21165715] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian, or mechanic, target of rapamycin (mTOR) signaling is a crucial factor in the regulation of the energy balance that functions as an energy sensor in the body. The present review explores how the mTOR/S6k intracellular pathway is involved in modulating the production of different signals such as ghrelin and nesfatin-1 in the gastrointestinal tract to regulate food intake and body weight. The role of gastric mTOR signaling in different physiological processes was studied in depth through different genetic models that allow the modulation of mTOR signaling in the stomach and specifically in gastric X/A type cells. It has been described that mTOR signaling in X/A-like gastric cells has a relevant role in the regulation of glucose and lipid homeostasis due to its interaction with different organs such as liver and adipose tissue. These findings highlight possible therapeutic strategies, with the gut–brain axis being one of the most promising targets in the treatment of obesity.
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Affiliation(s)
- Veronica Pena-Leon
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Raquel Perez-Lois
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Luisa Maria Seoane
- Grupo Fisiopatología Endocrina, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Instituto de Investigación Sanitaria, Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; (V.P.-L.); (R.P.-L.)
- Centro de Investigacion Biomedica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence:
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10
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Negrón AL, Yu G, Boehm U, Acosta-Martínez M. Targeted Deletion of PTEN in Kisspeptin Cells Results in Brain Region- and Sex-Specific Effects on Kisspeptin Expression and Gonadotropin Release. Int J Mol Sci 2020; 21:ijms21062107. [PMID: 32204355 PMCID: PMC7139936 DOI: 10.3390/ijms21062107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 02/06/2023] Open
Abstract
Kisspeptin-expressing neurons in the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC) of the hypothalamus relay hormonal and metabolic information to gonadotropin-releasing hormone neurons, which in turn regulate pituitary and gonadal function. Phosphatase and tensin homolog (PTEN) blocks phosphatidylinositol 3-kinase (PI3K), a signaling pathway utilized by peripheral factors to transmit their signals. However, whether PTEN signaling in kisspeptin neurons helps to integrate peripheral hormonal cues to regulate gonadotropin release is unknown. To address this question, we generated mice with a kisspeptin cell-specific deletion of Pten (Kiss-PTEN KO), and first assessed kisspeptin protein expression and gonadotropin release in these animals. Kiss-PTEN KO mice displayed a profound sex and region-specific kisspeptin neuron hyperthrophy. We detected both kisspeptin neuron hyperthrophy as well as increased kisspeptin fiber densities in the AVPV and ARC of Kiss-PTEN KO females and in the ARC of Kiss-PTEN KO males. Moreover, Kiss-PTEN KO mice showed a reduced gonadotropin release in response to gonadectomy. We also found a hyperactivation of mTOR, a downstream PI3K target and central regulator of cell metabolism, in the AVPV and ARC of Kiss-PTEN KO females but not males. Fasting, known to inhibit hypothalamic kisspeptin expression and luteinizing hormone levels, failed to induce these changes in Kiss-PTEN KO females. We conclude that PTEN signaling regulates kisspeptin protein synthesis in both sexes and that its role as a metabolic signaling molecule in kisspeptin neurons is sex-specific.
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Affiliation(s)
- Ariel L. Negrón
- Graduate Program in Neuroscience, Stony Brook University, Stony Brook, NY 11794, USA;
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Guiqin Yu
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Ulrich Boehm
- Experimental Pharmacology, Center for Molecular Signaling (PZMS), Saarland University School of Medicine, 66421 Homburg, Germany;
| | - Maricedes Acosta-Martínez
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA;
- Correspondence: ; Tel.: +1-631-444-6075; Fax: +1-631-444-3432
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11
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Hurtado-Carneiro V, Pérez-García A, Alvarez E, Sanz C. PAS Kinase: A Nutrient and Energy Sensor "Master Key" in the Response to Fasting/Feeding Conditions. Front Endocrinol (Lausanne) 2020; 11:594053. [PMID: 33391184 PMCID: PMC7775648 DOI: 10.3389/fendo.2020.594053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/18/2020] [Indexed: 12/24/2022] Open
Abstract
The protein kinase with PAS domains (PASK) is a nutrient and energy sensor located in the cells of multiple organs. Many of the recent findings for understanding PASK functions in mammals have been reported in studies involving PASK-deficient mice. This minireview summarizes the PASK role in the control of fasting and feeding responses, focusing especially on the hypothalamus and liver. In 2013, PASK was identified in the hypothalamic areas involved in feeding behavior, and its expression was regulated under fasting/refeeding conditions. Furthermore, it plays a role in coordinating the activation/inactivation of the hypothalamic energy sensors AMPK and mTOR/S6K1 pathways in response to fasting. On the other hand, PASK deficiency prevents the development of obesity and non-alcoholic fatty liver in mice fed with a high-fat diet. This protection is explained by the re-establishment of several high-fat diet metabolic alterations produced in the expression of hepatic transcription factors and key enzymes that control the main metabolic pathways involved in maintaining metabolic homeostasis in fasting/feeding responses. This minireview covers the effects of PASK inactivation in the expression of certain transcription factors and target enzymes in several metabolic pathways under situations such as fasting and feeding with either a standard or a high-fat diet.
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Affiliation(s)
- Verónica Hurtado-Carneiro
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Complutense University of Madrid, Institute of Medical Research at the Hospital Clínico San Carlos (IdISSC), Ciudad Universitaria, Madrid, Spain
- Department of Physiology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain
- *Correspondence: Verónica Hurtado-Carneiro,
| | - Ana Pérez-García
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Complutense University of Madrid, Institute of Medical Research at the Hospital Clínico San Carlos (IdISSC), Ciudad Universitaria, Madrid, Spain
| | - Elvira Alvarez
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Complutense University of Madrid, Institute of Medical Research at the Hospital Clínico San Carlos (IdISSC), Ciudad Universitaria, Madrid, Spain
| | - Carmen Sanz
- Department of Cell Biology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain
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12
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Tavares MR, Lemes SF, de Fante T, Saenz de Miera C, Pavan ICB, Bezerra RMN, Prada PO, Torsoni MA, Elias CF, Simabuco FM. Modulation of hypothalamic S6K1 and S6K2 alters feeding behavior and systemic glucose metabolism. J Endocrinol 2020; 244:71-82. [PMID: 31557728 PMCID: PMC8010582 DOI: 10.1530/joe-19-0364] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 09/26/2019] [Indexed: 11/08/2022]
Abstract
The mTOR/S6Ks signaling is one of the intracellular pathways important for metabolic control, acting both peripherally and centrally. In the hypothalamus, mTOR/S6Ks axis mediates the action of leptin and insulin and can modulate the expression of neuropeptides. We analyzed the role of different S6Ks isoforms in the hypothalamic regulation of metabolism. We observed decreased food intake and decreased expression of agouti-related peptide (AgRP) following intracerebroventricular (icv) injections of adenoviral-mediated overexpression of three different S6Ks isoforms. Moreover, mice overexpressing p70-S6K1 in undefined periventricular hypothalamic neurons presented changes in glucose metabolism, as an increase in gluconeogenesis. To further evaluate the hypothalamic role of a less-studied S6K isoform, p54-S6K2, we used a Cre-LoxP approach to specifically overexpress it in AgRP neurons. Our findings demonstrate the potential participation of S6K2 in AgRP neurons regulating feeding behavior.
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Affiliation(s)
- Mariana Rosolen Tavares
- Multidisciplinary Laboratory of Food and Health (LABMAS), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
- Laboratory of Metabolic Disorders (LABDIME), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Simone Ferreira Lemes
- Laboratory of Metabolic Disorders (LABDIME), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Thais de Fante
- Laboratory of Metabolic Disorders (LABDIME), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Cristina Saenz de Miera
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Isadora Carolina Betim Pavan
- Multidisciplinary Laboratory of Food and Health (LABMAS), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
- Laboratory of Metabolic Disorders (LABDIME), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Rosangela Maria Neves Bezerra
- Multidisciplinary Laboratory of Food and Health (LABMAS), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Patricia Oliveira Prada
- Laboratory of Molecular Research in Obesity (LABIMO), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Marcio Alberto Torsoni
- Laboratory of Metabolic Disorders (LABDIME), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
| | - Carol Fuzeti Elias
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Fernando Moreira Simabuco
- Multidisciplinary Laboratory of Food and Health (LABMAS), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
- Laboratory of Metabolic Disorders (LABDIME), School of Applied Sciences (FCA), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
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13
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Central administration of insulin and refeeding lead to the phosphorylation of AKT, but not FOXO1, in the hypothalamus of broiler chicks. Physiol Behav 2019; 210:112644. [PMID: 31398442 DOI: 10.1016/j.physbeh.2019.112644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 11/23/2022]
Abstract
Several studies in rodents and layer chickens have demonstrated that insulin upregulates hypothalamic AKT-mediated signaling and expression of proopiomelanocortin (POMC, the precursor of alpha-melanocyte stimulating hormone, an anorexigenic peptide) and suppresses appetite in these animals. However, a previous study has also reported that insulin fails to suppress food intake in broiler chicks. In the present study, no significant differences were observed in hypothalamic AKT and forkhead box O1 (FOXO1) phosphorylation levels between broiler and layer chicks. The phosphorylation rate of AKT, but not that of FOXO1, increased in the hypothalami of broilers refed for 1 h after a 24-h fast, with a corresponding increase in plasma insulin concentration. Intracerebroventricular (ICV) administration of 50 pmol insulin, which could decrease food intake in broiler chicks, significantly increased the AKT phosphorylation rate, whereas no significant change was observed in FOXO1 phosphorylation or POMC expression after ICV insulin administration. These findings suggest that hypothalamic AKT responds to insulin in broiler chicks, but FOXO1-mediated regulation of POMC expression is not induced by insulin, which may be one of the causes of excessive food intake in broiler chickens.
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14
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Allison MB, Pan W, MacKenzie A, Patterson C, Shah K, Barnes T, Cheng W, Rupp A, Olson DP, Myers MG. Defining the Transcriptional Targets of Leptin Reveals a Role for Atf3 in Leptin Action. Diabetes 2018; 67:1093-1104. [PMID: 29535089 PMCID: PMC5961413 DOI: 10.2337/db17-1395] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/27/2018] [Indexed: 12/22/2022]
Abstract
Leptin acts via its receptor (LepRb) to modulate gene expression in hypothalamic LepRb-expressing neurons, thereby controlling energy balance and glucose homeostasis. Despite the importance of the control of gene expression in hypothalamic LepRb neurons for leptin action, the transcriptional targets of LepRb signaling have remained undefined because LepRb cells contribute a small fraction to the aggregate transcriptome of the brain regions in which they reside. We thus employed translating ribosome affinity purification followed by RNA sequencing to isolate and analyze mRNA from the hypothalamic LepRb neurons of wild-type or leptin-deficient (Lepob/ob) mice treated with vehicle or exogenous leptin. Although the expression of most of the genes encoding the neuropeptides commonly considered to represent the main targets of leptin action were altered only following chronic leptin deprivation, our analysis revealed other transcripts that were coordinately regulated by leptin under multiple treatment conditions. Among these, acute leptin treatment increased expression of the transcription factor Atf3 in LepRb neurons. Furthermore, ablation of Atf3 from LepRb neurons (Atf3LepRbKO mice) decreased leptin efficacy and promoted positive energy balance in mice. Thus, this analysis revealed the gene targets of leptin action, including Atf3, which represents a cellular mediator of leptin action.
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MESH Headings
- Activating Transcription Factor 3/agonists
- Activating Transcription Factor 3/chemistry
- Activating Transcription Factor 3/genetics
- Activating Transcription Factor 3/metabolism
- Animals
- Crosses, Genetic
- Diabetes Mellitus/drug therapy
- Diabetes Mellitus/metabolism
- Diabetes Mellitus/pathology
- Energy Metabolism/drug effects
- Female
- Gene Expression Profiling
- Gene Expression Regulation/drug effects
- Hypoglycemic Agents/pharmacology
- Hypoglycemic Agents/therapeutic use
- Hypothalamus/cytology
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Hypothalamus/pathology
- Leptin/analogs & derivatives
- Leptin/metabolism
- Leptin/pharmacology
- Leptin/therapeutic use
- Lipotropic Agents/pharmacology
- Lipotropic Agents/therapeutic use
- Male
- Mice, Knockout
- Mice, Mutant Strains
- Mice, Transgenic
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/chemistry
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Neurons/pathology
- Obesity/drug therapy
- Obesity/metabolism
- Obesity/pathology
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- Receptors, Leptin/agonists
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Sequence Analysis, RNA
- Signal Transduction/drug effects
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Affiliation(s)
- Margaret B Allison
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - Warren Pan
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
| | | | - Christa Patterson
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Kimi Shah
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Tammy Barnes
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Wenwen Cheng
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Alan Rupp
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - David P Olson
- Division of Pediatric Endocrinology, Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI
| | - Martin G Myers
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
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15
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Barone I, Melani R, Mainardi M, Scabia G, Scali M, Dattilo A, Ceccarini G, Vitti P, Santini F, Maffei L, Pizzorusso T, Maffei M. Fluoxetine Modulates the Activity of Hypothalamic POMC Neurons via mTOR Signaling. Mol Neurobiol 2018; 55:9267-9279. [PMID: 29663284 DOI: 10.1007/s12035-018-1052-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 03/29/2018] [Indexed: 01/01/2023]
Abstract
Hypothalamic proopiomelanocortin (POMC) neurons are important players in the regulation of energy homeostasis; we previously demonstrated that environmental stimulation excites arcuate nucleus circuits to undergo plastic remodeling, leading to altered ratio between excitatory and inhibitory synaptic contacts on these neurons. The widely used selective serotonin reuptake inhibitor fluoxetine (FLX) is known to affect body weight. On the other hand, FLX administration mimics the effects of environmental stimulation on synaptic plasticity in the hippocampus and cortex. The mammalian target of rapamycin (mTOR) pathway is instrumental in these phenomena. Thus, we aimed at investigating whether and how FLX affects POMC neurons activity and hypothalamic mTOR function. Adult mice expressing green fluorescent protein (GFP) under the POMC promoter were treated with FLX for 3 weeks resulting in diminished body weight. Patch clamp recordings performed on POMC neurons indicate that FLX increases their firing rate and the excitatory AMPA-mediated transmission, and reduces the inhibitory GABAergic currents at presynaptic level. Immunofluorescence studies indicate that FLX increases the ratio between excitatory and inhibitory synaptic contacts on POMC neurons. These changes are associated with an increased activity of the hypothalamic mTOR pathway. Use of the mTOR inhibitor rapamycin blunts the effects of FLX on body weight and on functional and structural plasticity of POMC neurons. Our findings indicate that FLX is able to remodel POMC neurons, and that this may be partly mediated by the mTOR signaling pathway.
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Affiliation(s)
- Ilaria Barone
- Dulbecco Telethon Institute, Rome, Italy
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy
| | - Riccardo Melani
- Institute of Neuroscience, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy
| | - Marco Mainardi
- Institute of Neuroscience, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy
- Bio@SNS, Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126, Pisa, Italy
| | - Gaia Scabia
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy
- Institute of Clinical Physiology, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy
| | - Manuela Scali
- Institute of Neuroscience, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy
| | - Alessia Dattilo
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy
- Institute of Clinical Physiology, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy
| | - Giovanni Ceccarini
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy
| | - Paolo Vitti
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy
| | - Ferruccio Santini
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy
| | - Lamberto Maffei
- Institute of Neuroscience, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy
| | - Tommaso Pizzorusso
- Institute of Neuroscience, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy.
- NEUROFARBA Department, Università di Firenze, Via di San Savi 26, 50235, Florence, Italy.
| | - Margherita Maffei
- Dulbecco Telethon Institute, Rome, Italy.
- Department of Clinical and Experimental Medicine, Obesity Center at the Endocrinology Unit, Via Paradisa 2, 56126, Pisa, Italy.
- Institute of Clinical Physiology, National Research Council, Via Moruzzi 1, 56124, Pisa, Italy.
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16
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Burke LK, Darwish T, Cavanaugh AR, Virtue S, Roth E, Morro J, Liu SM, Xia J, Dalley JW, Burling K, Chua S, Vidal-Puig T, Schwartz GJ, Blouet C. mTORC1 in AGRP neurons integrates exteroceptive and interoceptive food-related cues in the modulation of adaptive energy expenditure in mice. eLife 2017; 6. [PMID: 28532548 PMCID: PMC5441868 DOI: 10.7554/elife.22848] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 04/18/2017] [Indexed: 01/19/2023] Open
Abstract
Energy dissipation through interscapular brown adipose tissue (iBAT) thermogenesis is an important contributor to adaptive energy expenditure. However, it remains unresolved how acute and chronic changes in energy availability are detected by the brain to adjust iBAT activity and maintain energy homeostasis. Here, we provide evidence that AGRP inhibitory tone to iBAT represents an energy-sparing circuit that integrates environmental food cues and internal signals of energy availability. We establish a role for the nutrient-sensing mTORC1 signaling pathway within AGRP neurons in the detection of environmental food cues and internal signals of energy availability, and in the bi-directional control of iBAT thermogenesis during nutrient deficiency and excess. Collectively, our findings provide insights into how mTORC1 signaling within AGRP neurons surveys energy availability to engage iBAT thermogenesis, and identify AGRP neurons as a neuronal substrate for the coordination of energy intake and adaptive expenditure under varying physiological and environmental contexts. DOI:http://dx.doi.org/10.7554/eLife.22848.001 Losing weight through dieting can be difficult. Weight loss strategies often prove ineffective because the body works like a thermostat and couples what we eat to the number of calories we burn. When we eat less, our bodies compensate and burn fewer calories, which makes losing weight harder. The brain is the master regulator of this caloric thermostat, but it is not clear how it adjusts our energy expenditure to account for how much we have eaten. A structure deep within the brain called the hypothalamus, which helps regulate appetite, is thought to be involved in the caloric thermostat. Activating a group of neurons within the hypothalamus called the agouti-related neuropeptide (AGRP) neurons causes animals to consume large quantities of food. By contrast, inhibiting AGRP neurons causes animals to stop eating almost entirely. Burke et al. studied AGRP neurons in mice. The experiments show that artificially activating the neurons in mice that don’t have access to food increases the animals’ activity levels but reduces the rate at which they burn calories, which helps the mice to maintain their existing weight. Allowing the mice to eat, or even just to see and smell food, switches off this effect and returns energy expenditure to normal. Finally, exposing mice to a high-fat diet for several days inhibits their AGRP neurons, and causes the animals to burn calories at a faster rate. By using up excess calories, this change also helps the animals maintain their existing body weight. The findings of Burke et al. show that AGRP neurons are a key component of the caloric thermostat. By adjusting the rate at which the body burns calories, AGRP neurons can compensate for any changes in food intake and so limit changes in body weight. This work opens up the possibility of developing therapies that disconnect energy expenditure from energy intake to help maintain long-term weight loss. DOI:http://dx.doi.org/10.7554/eLife.22848.002
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Affiliation(s)
- Luke K Burke
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Tamana Darwish
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Althea R Cavanaugh
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Sam Virtue
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Emma Roth
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Joanna Morro
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Shun-Mei Liu
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Jing Xia
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Jeffrey W Dalley
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom.,Department of Psychiatry, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Keith Burling
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Streamson Chua
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Toni Vidal-Puig
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Gary J Schwartz
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Clémence Blouet
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
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17
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Hellsten SV, Eriksson MM, Lekholm E, Arapi V, Perland E, Fredriksson R. The gene expression of the neuronal protein, SLC38A9, changes in mouse brain after in vivo starvation and high-fat diet. PLoS One 2017; 12:e0172917. [PMID: 28235079 PMCID: PMC5325605 DOI: 10.1371/journal.pone.0172917] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/03/2017] [Indexed: 11/18/2022] Open
Abstract
SLC38A9 is characterized as a lysosomal component of the amino acid sensing Ragulator-RAG GTPase complex, controlling the mechanistic target of rapamycin complex 1 (mTORC1). Here, immunohistochemistry was used to map SLC38A9 in mouse brain and staining was detected throughout the brain, in cortex, hypothalamus, thalamus, hippocampus, brainstem and cerebellum. More specifically, immunostaining was found in areas known to be involved in amino acid sensing and signaling pathways e.g. piriform cortex and hypothalamus. SLC38A9 immunoreactivity co-localized with both GABAergic and glutamatergic neurons, but not with astrocytes. SLC38A9 play a key role in the mTORC1 pathway, and therefore we performed in vivo starvation and high-fat diet studies, to measure gene expression alterations in specific brain tissues and in larger brain regions. Following starvation, Slc38a9 was upregulated in brainstem and cortex, and in anterior parts of the brain (Bregma 3.2 to -2.1mm). After high-fat diet, Slc38a9 was specifically upregulated in hypothalamus, while overall downregulation was noticed throughout the brain (Bregma 3.2 to -8.6mm).
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Affiliation(s)
- Sofie V. Hellsten
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology, Uppsala University, Uppsala SE, Sweden
- * E-mail:
| | - Mikaela M. Eriksson
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology, Uppsala University, Uppsala SE, Sweden
| | - Emilia Lekholm
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology, Uppsala University, Uppsala SE, Sweden
| | - Vasiliki Arapi
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology, Uppsala University, Uppsala SE, Sweden
| | - Emelie Perland
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology, Uppsala University, Uppsala SE, Sweden
| | - Robert Fredriksson
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology, Uppsala University, Uppsala SE, Sweden
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18
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Pereira JADS, da Silva FC, de Moraes-Vieira PMM. The Impact of Ghrelin in Metabolic Diseases: An Immune Perspective. J Diabetes Res 2017; 2017:4527980. [PMID: 29082258 PMCID: PMC5610818 DOI: 10.1155/2017/4527980] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 07/07/2017] [Accepted: 07/31/2017] [Indexed: 01/22/2023] Open
Abstract
Obesity and insulin resistance have reached epidemic proportions. Obesogenic conditions are associated with increased risk for the development of other comorbidities and obesity-related diseases. In metabolic disorders, there is chronic low-grade inflammation induced by the activation of immune cells, especially in metabolic relevant organs such as white adipose tissue (WAT). These immune cells are regulated by environmental and systemic cues. Ghrelin is a peptide secreted mainly by X/A-like gastric cells and acts through the growth hormone secretagogue receptor (GHS-R). This receptor is broadly expressed in the central nervous system (CNS) and in several cell types, including immune cells. Studies show that ghrelin induces an orexigenic state, and there is increasing evidence implicating an immunoregulatory role for ghrelin. Ghrelin mainly acts on the innate and adaptive immune systems to suppress inflammation and induce an anti-inflammatory profile. In this review, we discuss the immunoregulatory roles of ghrelin, the mechanisms by which ghrelin acts and potential pharmacological applications for ghrelin in the treatment of obesity-associated inflammatory diseases, such as type 2 diabetes (T2D).
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Affiliation(s)
- Jéssica Aparecida da Silva Pereira
- Laboratory of Immunometabolism, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, São Paulo, SP, Brazil
- Department of Immunology, Institute of Biomedical Science, University of São Paulo, São Paulo, SP, Brazil
| | - Felipe Corrêa da Silva
- Laboratory of Immunometabolism, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, São Paulo, SP, Brazil
| | - Pedro Manoel Mendes de Moraes-Vieira
- Laboratory of Immunometabolism, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, São Paulo, SP, Brazil
- Department of Immunology, Institute of Biomedical Science, University of São Paulo, São Paulo, SP, Brazil
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19
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Contribution of adaptive thermogenesis to the hypothalamic regulation of energy balance. Biochem J 2016; 473:4063-4082. [DOI: 10.1042/bcj20160012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 08/13/2016] [Accepted: 08/30/2016] [Indexed: 12/12/2022]
Abstract
Obesity and its related disorders are among the most pervasive diseases in contemporary societies, and there is an urgent need for new therapies and preventive approaches. Given (i) our poor social capacity to correct unhealthy habits, and (ii) our evolutionarily genetic predisposition to store excess energy as fat, the current environment of caloric surplus makes the treatment of obesity extremely difficult. During the last few decades, an increasing number of methodological approaches have increased our knowledge of the neuroanatomical basis of the control of energy balance. Compelling evidence underlines the role of the hypothalamus as a homeostatic integrator of metabolic information and its ability to adjust energy balance. A greater understanding of the neural basis of the hypothalamic regulation of energy balance might indeed pave the way for new therapeutic targets. In this regard, it has been shown that several important peripheral signals, such as leptin, thyroid hormones, oestrogens and bone morphogenetic protein 8B, converge on common energy sensors, such as AMP-activated protein kinase to modulate sympathetic tone on brown adipose tissue. This knowledge may open new ways to counteract the chronic imbalance underlying obesity. Here, we review the current state of the art on the role of hypothalamus in the regulation of energy balance with particular focus on thermogenesis.
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20
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Hu F, Xu Y, Liu F. Hypothalamic roles of mTOR complex I: integration of nutrient and hormone signals to regulate energy homeostasis. Am J Physiol Endocrinol Metab 2016; 310:E994-E1002. [PMID: 27166282 PMCID: PMC4935144 DOI: 10.1152/ajpendo.00121.2016] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/06/2016] [Indexed: 12/31/2022]
Abstract
Mammalian or mechanistic target of rapamycin (mTOR) senses nutrient, energy, and hormone signals to regulate metabolism and energy homeostasis. mTOR activity in the hypothalamus, which is associated with changes in energy status, plays a critical role in the regulation of food intake and body weight. mTOR integrates signals from a variety of "energy balancing" hormones such as leptin, insulin, and ghrelin, although its action varies in response to these distinct hormonal stimuli as well as across different neuronal populations. In this review, we summarize and highlight recent findings regarding the functional roles of mTOR complex 1 (mTORC1) in the hypothalamus specifically in its regulation of body weight, energy expenditure, and glucose/lipid homeostasis. Understanding the role and underlying mechanisms behind mTOR-related signaling in the brain will undoubtedly pave new avenues for future therapeutics and interventions that can combat obesity, insulin resistance, and diabetes.
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Affiliation(s)
- Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China;
| | - Yong Xu
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas; and
| | - Feng Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China; Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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21
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Yavari A, Stocker CJ, Ghaffari S, Wargent ET, Steeples V, Czibik G, Pinter K, Bellahcene M, Woods A, Martínez de Morentin PB, Cansell C, Lam BYH, Chuster A, Petkevicius K, Nguyen-Tu MS, Martinez-Sanchez A, Pullen TJ, Oliver PL, Stockenhuber A, Nguyen C, Lazdam M, O'Dowd JF, Harikumar P, Tóth M, Beall C, Kyriakou T, Parnis J, Sarma D, Katritsis G, Wortmann DDJ, Harper AR, Brown LA, Willows R, Gandra S, Poncio V, de Oliveira Figueiredo MJ, Qi NR, Peirson SN, McCrimmon RJ, Gereben B, Tretter L, Fekete C, Redwood C, Yeo GSH, Heisler LK, Rutter GA, Smith MA, Withers DJ, Carling D, Sternick EB, Arch JRS, Cawthorne MA, Watkins H, Ashrafian H. Chronic Activation of γ2 AMPK Induces Obesity and Reduces β Cell Function. Cell Metab 2016; 23:821-36. [PMID: 27133129 PMCID: PMC4873618 DOI: 10.1016/j.cmet.2016.04.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 03/01/2016] [Accepted: 04/01/2016] [Indexed: 12/02/2022]
Abstract
Despite significant advances in our understanding of the biology determining systemic energy homeostasis, the treatment of obesity remains a medical challenge. Activation of AMP-activated protein kinase (AMPK) has been proposed as an attractive strategy for the treatment of obesity and its complications. AMPK is a conserved, ubiquitously expressed, heterotrimeric serine/threonine kinase whose short-term activation has multiple beneficial metabolic effects. Whether these translate into long-term benefits for obesity and its complications is unknown. Here, we observe that mice with chronic AMPK activation, resulting from mutation of the AMPK γ2 subunit, exhibit ghrelin signaling-dependent hyperphagia, obesity, and impaired pancreatic islet insulin secretion. Humans bearing the homologous mutation manifest a congruent phenotype. Our studies highlight that long-term AMPK activation throughout all tissues can have adverse metabolic consequences, with implications for pharmacological strategies seeking to chronically activate AMPK systemically to treat metabolic disease.
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Affiliation(s)
- Arash Yavari
- Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
| | - Claire J Stocker
- The Buckingham Institute for Translational Medicine, University of Buckingham, Buckingham MK18 1EG, UK
| | - Sahar Ghaffari
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Edward T Wargent
- The Buckingham Institute for Translational Medicine, University of Buckingham, Buckingham MK18 1EG, UK
| | - Violetta Steeples
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Gabor Czibik
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Katalin Pinter
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Mohamed Bellahcene
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Angela Woods
- Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, London SW7 2AZ, UK
| | | | - Céline Cansell
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Brian Y H Lam
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge CB2 0QQ, UK
| | - André Chuster
- Pos Graduação Ciências Médicas, Faculdade Ciências Médicas, Universidade Federal de Minas Gerais, Belo Horizonte-MG 31270-901, Brazil
| | - Kasparas Petkevicius
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge CB2 0QQ, UK
| | - Marie-Sophie Nguyen-Tu
- Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London SW7 2AZ, UK
| | - Aida Martinez-Sanchez
- Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London SW7 2AZ, UK
| | - Timothy J Pullen
- Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London SW7 2AZ, UK
| | - Peter L Oliver
- MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Alexander Stockenhuber
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Chinh Nguyen
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Merzaka Lazdam
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Jacqueline F O'Dowd
- The Buckingham Institute for Translational Medicine, University of Buckingham, Buckingham MK18 1EG, UK
| | - Parvathy Harikumar
- The Buckingham Institute for Translational Medicine, University of Buckingham, Buckingham MK18 1EG, UK
| | - Mónika Tóth
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest 1083, Hungary
| | - Craig Beall
- Cardiovascular and Diabetes Medicine, Medical Research Institute, University of Dundee, Dundee DD1 9SY, UK
| | - Theodosios Kyriakou
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Julia Parnis
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Dhruv Sarma
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - George Katritsis
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Diana D J Wortmann
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Andrew R Harper
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Laurence A Brown
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
| | - Robin Willows
- Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, London SW7 2AZ, UK
| | - Silvia Gandra
- Pos Graduação Ciências Médicas, Faculdade Ciências Médicas, Universidade Federal de Minas Gerais, Belo Horizonte-MG 31270-901, Brazil
| | - Victor Poncio
- Universidade Estadual de Campinas, Campinas-SP 13083-970, Brazil
| | | | - Nathan R Qi
- Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Stuart N Peirson
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
| | - Rory J McCrimmon
- Cardiovascular and Diabetes Medicine, Medical Research Institute, University of Dundee, Dundee DD1 9SY, UK
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest 1083, Hungary
| | - László Tretter
- Department of Medical Biochemistry, Semmelweis University, Budapest 1085, Hungary; MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest 1085, Hungary
| | - Csaba Fekete
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest 1083, Hungary; Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, MA 02111, USA
| | - Charles Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Giles S H Yeo
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge CB2 0QQ, UK
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Guy A Rutter
- Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London SW7 2AZ, UK
| | - Mark A Smith
- Metabolic Signalling Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, UK
| | - Dominic J Withers
- Metabolic Signalling Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, UK
| | - David Carling
- Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, London SW7 2AZ, UK
| | - Eduardo B Sternick
- Pos Graduação Ciências Médicas, Faculdade Ciências Médicas, Universidade Federal de Minas Gerais, Belo Horizonte-MG 31270-901, Brazil
| | - Jonathan R S Arch
- The Buckingham Institute for Translational Medicine, University of Buckingham, Buckingham MK18 1EG, UK
| | - Michael A Cawthorne
- The Buckingham Institute for Translational Medicine, University of Buckingham, Buckingham MK18 1EG, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Houman Ashrafian
- Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Experimental Therapeutics, Clinical Science Group, New Medicines, UCB Pharma S.A., Slough, Berkshire SL1 3WE, UK.
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22
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Biever A, Valjent E, Puighermanal E. Ribosomal Protein S6 Phosphorylation in the Nervous System: From Regulation to Function. Front Mol Neurosci 2015; 8:75. [PMID: 26733799 PMCID: PMC4679984 DOI: 10.3389/fnmol.2015.00075] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 11/23/2015] [Indexed: 01/31/2023] Open
Abstract
Since the discovery of the phosphorylation of the 40S ribosomal protein S6 (rpS6) about four decades ago, much effort has been made to uncover the molecular mechanisms underlying the regulation of this post-translational modification. In the field of neuroscience, rpS6 phosphorylation is commonly used as a readout of the mammalian target of rapamycin complex 1 signaling activation or as a marker for neuronal activity. Nevertheless, its biological role in neurons still remains puzzling. Here we review the pharmacological and physiological stimuli regulating this modification in the nervous system as well as the pathways that transduce these signals into rpS6 phosphorylation. Altered rpS6 phosphorylation observed in various genetic and pathophysiological mouse models is also discussed. Finally, we examine the current state of knowledge on the physiological role of this post-translational modification and highlight the questions that remain to be addressed.
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Affiliation(s)
- Anne Biever
- Centre National de la Recherche Scientifique, UMR5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale, U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Emmanuel Valjent
- Centre National de la Recherche Scientifique, UMR5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale, U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Emma Puighermanal
- Centre National de la Recherche Scientifique, UMR5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale, U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
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23
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Labbé SM, Caron A, Lanfray D, Monge-Rofarello B, Bartness TJ, Richard D. Hypothalamic control of brown adipose tissue thermogenesis. Front Syst Neurosci 2015; 9:150. [PMID: 26578907 PMCID: PMC4630288 DOI: 10.3389/fnsys.2015.00150] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 10/20/2015] [Indexed: 12/21/2022] Open
Abstract
It has long been known, in large part from animal studies, that the control of brown adipose tissue (BAT) thermogenesis is insured by the central nervous system (CNS), which integrates several stimuli in order to control BAT activation through the sympathetic nervous system (SNS). SNS-mediated BAT activity is governed by diverse neurons found in brain structures involved in homeostatic regulations and whose activity is modulated by various factors including oscillations of energy fluxes. The characterization of these neurons has always represented a challenging issue. The available literature suggests that the neuronal circuits controlling BAT thermogenesis are largely part of an autonomic circuitry involving the hypothalamus, brainstem and the SNS efferent neurons. In the present review, we recapitulate the latest progresses in regards to the hypothalamic regulation of BAT metabolism. We briefly addressed the role of the thermoregulatory pathway and its interactions with the energy balance systems in the control of thermogenesis. We also reviewed the involvement of the brain melanocortin and endocannabinoid systems as well as the emerging role of steroidogenic factor 1 (SF1) neurons in BAT thermogenesis. Finally, we examined the link existing between these systems and the homeostatic factors that modulate their activities.
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Affiliation(s)
- Sebastien M Labbé
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Alexandre Caron
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Damien Lanfray
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Boris Monge-Rofarello
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
| | - Timothy J Bartness
- Department of Biology, Center for Obesity Reversal (COR), Georgia State University Atlanta, GA, USA
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval Québec, QC, Canada
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24
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Sadagurski M, Landeryou T, Cady G, Bartke A, Bernal-Mizrachi E, Miller RA. Transient early food restriction leads to hypothalamic changes in the long-lived crowded litter female mice. Physiol Rep 2015; 3:e12379. [PMID: 25907790 PMCID: PMC4425981 DOI: 10.14814/phy2.12379] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 03/19/2015] [Accepted: 03/25/2015] [Indexed: 12/27/2022] Open
Abstract
Transient nutrient restriction in the 3 weeks between birth and weaning (producing "crowded litter" or CL mice) leads to a significant increase in lifespan and is associated with permanent changes in energy homeostasis, leptin, and insulin sensitivity. Here, we show this brief period of early food restriction leads to permanent modulation of the arcuate nucleus of the hypothalamus (ARH), markedly increasing formation of both orexigenic agouti-related peptide (AgRP) and anorexigenic proopiomelanocortin (POMC) projections to the paraventricular nucleus of the hypothalamus (PVH). An additional 4 weeks of caloric restriction, after weaning, does not further intensify the formation of AgRP and POMC projections. Acute leptin stimulation of 12-month-old mice leads to a stronger increase in the levels of hypothalamic pStat3 and cFos activity in CL mice than in controls, suggesting that preweaning food restriction leads to long-lasting enhancement of leptin signaling. In contrast, FoxO1 nuclear exclusion in response to insulin is equivalent in young adult CL and control mice, suggesting that hypothalamic insulin signaling is not modulated by the crowded litter intervention. Markers of hypothalamic reactive gliosis associated with aging, such as Iba1-positive microglia and GFAP-positive astrocytes, are significantly reduced in CL mice as compared to controls at 12 and 22 months of age. Lastly, age-associated overproduction of TNF-α in microglial cells is reduced in CL mice than in age-matched controls. Together, these results suggest that transient early life nutrient deprivation leads to long-term hypothalamic changes which may contribute to the longevity of CL mice.
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Affiliation(s)
- Marianna Sadagurski
- Division of Geriatric and Palliative Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Taylor Landeryou
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan
| | - Gillian Cady
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan
| | - Andrzej Bartke
- Department of Internal Medicine-Geriatrics Research, Southern Illinois University School of Medicine, Springfield, Illinois
| | - Ernesto Bernal-Mizrachi
- Division of Metabolism Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan Endocrinology Section, Medical Service, Veterans Affairs Medical Center, Ann Arbor, Michigan
| | - Richard A Miller
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan
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25
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Muta K, Morgan DA, Rahmouni K. The role of hypothalamic mTORC1 signaling in insulin regulation of food intake, body weight, and sympathetic nerve activity in male mice. Endocrinology 2015; 156:1398-407. [PMID: 25574706 PMCID: PMC4399321 DOI: 10.1210/en.2014-1660] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Insulin action in the brain particularly the hypothalamus is critically involved in the regulation of several physiological processes, including energy homeostasis and sympathetic nerve activity, but the underlying mechanisms are poorly understood. The mechanistic target of rapamycin complex 1 (mTORC1) is implicated in the control of diverse cellular functions, including sensing nutrients and energy status. Here, we examined the role of hypothalamic mTORC1 in mediating the anorectic, weight-reducing, and sympathetic effects of central insulin action. In a mouse hypothalamic cell line (GT1-7), insulin treatment increased mTORC1 activity in a time-dependent manner. In addition, intracerebroventricular (ICV) administration of insulin to mice activated mTORC1 pathway in the hypothalamic arcuate nucleus, a key site of central action of insulin. Interestingly, inhibition of hypothalamic mTORC1 with rapamycin reversed the food intake- and body weight-lowering effects of ICV insulin. Rapamycin also abolished the ability of ICV insulin to cause lumbar sympathetic nerve activation. In GT1-7 cells, we found that insulin activation of mTORC1 pathway requires phosphatidylinositol 3-kinase (PI3K). Consistent with this, genetic disruption of PI3K in mice abolished insulin stimulation of hypothalamic mTORC1 signaling as well as the lumbar sympathetic nerve activation evoked by insulin. These results demonstrate the importance of mTORC1 pathway in the hypothalamus in mediating the action of insulin to regulate energy homeostasis and sympathetic nerve traffic. Our data also highlight the key role of PI3K as a link between insulin receptor and mTORC1 signaling in the hypothalamus.
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Affiliation(s)
- Kenjiro Muta
- Departments of Pharmacology (K.M., D.A.M., K.R.) and Internal Medicine (K.R.) and Fraternal Order of Eagles Diabetes Research Center (K.R.), University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
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26
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Saini S, Duraisamy AJ, Bayen S, Vats P, Singh SB. Role of BMP7 in appetite regulation, adipogenesis, and energy expenditure. Endocrine 2015; 48:405-9. [PMID: 25178649 DOI: 10.1007/s12020-014-0406-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/23/2014] [Indexed: 01/16/2023]
Abstract
Bone morphogenetic protein 7 (BMP7), also known as osteogenic protein-1 (OP-1) is a member of Transforming growth factor-β (TGF-β) family of proteins. Bone morphogenetic proteins were discovered in 1965 by Marshal Urist, of which BMP7 is of particular interest in this review being a leptin-independent anorexinogen and having role in energy expenditure in the brown adipose tissue, which makes it a potential target for preventing/treating obesity. As it has been established that Obesity displays a state of leptin-resistance, thus a protein-like BMP7 which acts through a leptin-independent pathway could give new therapeutic directions. This review will also discuss the synthesis and action of BMP7, along with its receptors and signal transduction. A brief note about BMP7-mediated brown fat development and energy balance is also discussed.
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Affiliation(s)
- Supriya Saini
- Endocrinology and Metabolism Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054, India
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27
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Melnik BC, John SM, Schmitz G. Milk consumption during pregnancy increases birth weight, a risk factor for the development of diseases of civilization. J Transl Med 2015; 13:13. [PMID: 25592553 PMCID: PMC4302093 DOI: 10.1186/s12967-014-0377-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/29/2014] [Indexed: 02/06/2023] Open
Abstract
Antenatal dietary lifestyle intervention and nutrition during pregnancy and early postnatal life are important for appropriate lifelong metabolic programming. Epidemiological evidence underlines the crucial role of increased birth weight as a risk factor for the development of chronic diseases of civilization such as obesity, diabetes and cancer. Obstetricians and general practitioners usually recommend milk consumption during pregnancy as a nutrient enriched in valuable proteins and calcium for bone growth. However, milk is not just a simple nutrient, but has been recognized to function as an endocrine signaling system promoting anabolism and postnatal growth by activating the nutrient-sensitive kinase mTORC1. Moreover, pasteurized cow’s milk transfers biologically active exosomal microRNAs into the systemic circulation of the milk consumer apparently affecting more than 11 000 human genes including the mTORC1-signaling pathway. This review provides literature evidence and evidence derived from translational research that milk consumption during pregnancy increases gestational, placental, fetal and birth weight. Increased birth weight is a risk factor for the development of diseases of civilization thus involving key disciplines of medicine. With regard to the presented evidence we suggest that dietary recommendations promoting milk consumption during pregnancy have to be re-evaluated.
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Affiliation(s)
- Bodo C Melnik
- Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabrück, Sedanstrasse 115, D-49090, Osnabrück, Germany.
| | - Swen Malte John
- Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabrück, Sedanstrasse 115, D-49090, Osnabrück, Germany.
| | - Gerd Schmitz
- Institute of Clinical Chemistry and Laboratory Medicine, University Clinics of Regensburg, Regensburg, Germany.
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28
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Haissaguerre M, Cota D. [Role of the mTOR pathway in the central regulation of energy balance]. Biol Aujourdhui 2015; 209:295-307. [PMID: 27021048 DOI: 10.1051/jbio/2016009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Indexed: 11/14/2022]
Abstract
The pathway of the mammalian (or mechanistic) target of rapamycin kinase (mTOR) responds to different signals such as nutrients and hormones and regulates many cellular functions as the synthesis of proteins and lipids, mitochondrial activity and the organization of the cytoskeleton. At the cellular level, mTOR forms two distinct complexes: mTORC1 and mTORC2. This review intends to summarize the various recent advances on the role of these two protein complexes in the central regulation of energy balance. mTORC1 activity modulates energy balance and metabolic responses by regulating the activity of neuronal populations, such as those located in the arcuate nucleus of the hypothalamus. Recent studies have shown that activity of the hypothalamic mTORC1 pathway varies according to cell and stimulus types, and that this signaling cascade regulates food intake and body weight in response to nutrients, such as leucine, and hormones like leptin, ghrelin and triiodothyronine. On the other hand, mTORC2 seems to be involved in the regulation of neuronal morphology and synaptic activity. However, its function in the central regulation of the energy balance is less known. Dysregulation of mTORC1 and mTORC2 is described in obesity and type 2 diabetes. Therefore, a better understanding of the molecular mechanisms involved in the regulation of energy balance by mTOR may lead to the identification of new therapeutic targets for the treatment of these metabolic pathologies.
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Affiliation(s)
- Magalie Haissaguerre
- Service Endocrinologie, Hôpital Haut Lévêque, CHU Bordeaux, 33600 Pessac, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33000 Bordeaux, France - Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33000 Bordeaux, France
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29
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Leptin induced GRP78 expression through the PI3K-mTOR pathway in neuronal cells. Sci Rep 2014; 4:7096. [PMID: 25403445 PMCID: PMC4235288 DOI: 10.1038/srep07096] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 10/30/2014] [Indexed: 12/15/2022] Open
Abstract
Leptin is a circulating hormone that plays a critical role in regulating energy expenditure and food intake. Evidence to suggest the involvement of endoplasmic reticulum (ER) stress in the development of obesity is increasing. To adapt against ER stress, cells trigger the unfolded protein response (UPR). The 78 kDa glucose-regulated protein (GRP78) is an ER chaperone that protects cells against ER stress by inducing protein folding. In the present study, we hypothesized that leptin may activate UPR and protect against ER stress associated with obesity. SH-SY5Y, a human neuroblastoma cell line stably transfected with the Ob-Rb leptin receptor (SH-SY5Y-ObRb), was treated with leptin. We demonstrated that leptin induced GRP78 expression. We then validated the mechanism responsible for the leptin-induced expression of GRP78. Interestingly, leptin-induced GRP78 expression was not dependent on IRE1-XBP1 pathway. On the other hand, the PI3K inhibitor, LY294002, and mTOR inhibitor, rapamycin, inhibited the leptin-induced expression of GRP78. These results suggested that the leptin-induced expression of GRP78 may be dependent on the PI3K-mTOR pathway. Leptin specifically induced GRP78 because the induction of the ER-apoptotic marker, CHOP, was not detected in leptin-treated cells. Therefore, leptin may upregulate the expression of GRP78, thereby protecting against ER stress associated with obesity.
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30
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Roa J, Tena-Sempere M. Connecting metabolism and reproduction: roles of central energy sensors and key molecular mediators. Mol Cell Endocrinol 2014; 397:4-14. [PMID: 25289807 DOI: 10.1016/j.mce.2014.09.027] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 09/26/2014] [Accepted: 09/26/2014] [Indexed: 12/15/2022]
Abstract
It is well established that pubertal activation of the reproductive axis and maintenance of fertility are critically dependent on the magnitude of body energy reserves and the metabolic state of the organism. Hence, conditions of impaired energy homeostasis often result in deregulation of puberty and reproduction, whereas gonadal dysfunction can be associated with the worsening of the metabolic profile and, eventually, changes in body weight. While much progress has taken place in our knowledge about the neuroendocrine mechanisms linking metabolism and reproduction, our understanding of how such dynamic interplay happens is still incomplete. As paradigmatic example, much has been learned in the last two decades on the reproductive roles of key metabolic hormones (such as leptin, insulin and ghrelin), their brain targets and the major transmitters and neuropeptides involved. Yet, the molecular mechanisms whereby metabolic information is translated and engages into the reproductive circuits remain largely unsolved. In this work, we will summarize recent developments in the characterization of the putative central roles of key cellular energy sensors, such as mTOR, in this phenomenon, and will relate these with other molecular mechanisms likely contributing to the brain coupling of energy balance and fertility. In doing so, we aim to provide an updated view of an area that, despite still underdeveloped, may be critically important to fully understand how reproduction and metabolism are tightly connected in health and disease.
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Affiliation(s)
- Juan Roa
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Cordoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Córdoba, Spain; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)/Hospital Universitario Reina Sofia, 14004 Córdoba, Spain
| | - Manuel Tena-Sempere
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Cordoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Córdoba, Spain; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)/Hospital Universitario Reina Sofia, 14004 Córdoba, Spain.
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31
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Haissaguerre M, Saucisse N, Cota D. Influence of mTOR in energy and metabolic homeostasis. Mol Cell Endocrinol 2014; 397:67-77. [PMID: 25109278 DOI: 10.1016/j.mce.2014.07.015] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 01/01/2023]
Abstract
The mechanistic (or mammalian) target of rapamycin couples a variety of different environmental signals, including nutrients and hormones, with the regulation of several energy-demanding cellular functions, spanning from protein and lipid synthesis to mitochondrial activity and cytoskeleton dynamics. mTOR forms two distinct protein complexes in cells, mTORC1 and mTORC2. This review focuses on recent advances made in understanding the roles played by these two complexes in the regulation of whole body metabolic homeostasis. Studies carried out in the past few years have shown that mTORC1 activity in the hypothalamus varies by cell and stimulus type, and that this complex is critically implicated in the regulation of food intake and body weight and in the central actions of both nutrients and hormones, such as leptin, ghrelin and triiodothyronine. As a regulator of cellular anabolic processes, mTORC1 activity in the periphery favors adipogenesis, lipogenesis, glucose uptake and beta-cell mass expansion. Much less is known about the function of mTORC2 in the hypothalamus, while in peripheral organs this second complex exerts roles strikingly similar to those described for mTORC1. Deregulation of mTORC1 and mTORC2 is associated with obesity, type 2 diabetes, cancer and neurodegenerative disorders. Insights on the exact relationship between mTORC1 and mTORC2 in the context of the regulation of metabolic homeostasis and on the specific molecular mechanisms engaged by these two complexes in such regulation may provide new avenues for therapy.
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Affiliation(s)
- Magalie Haissaguerre
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France
| | - Nicolas Saucisse
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France.
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Abstract
The role of neuronal noncoding RNAs in energy control of the body is not fully understood. The arcuate nucleus (ARC) of the hypothalamus comprises neurons regulating food intake and body weight. Here we show that Dicer-dependent loss of microRNAs in these neurons of adult (DicerCKO) mice causes chronic overactivation of the signaling pathways involving phosphatidylinositol-3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR) and an imbalance in the levels of neuropeptides, resulting in severe hyperphagic obesity. Similarly, the activation of PI3K-Akt-mTOR pathway due to Pten deletion in the adult forebrain leads to comparable weight increase. Conversely, the mTORC1 inhibitor rapamycin normalizes obesity in mice with an inactivated Dicer1 or Pten gene. Importantly, the continuous delivery of oligonucleotides mimicking microRNAs, which are predicted to target PI3K-Akt-mTOR pathway components, to the hypothalamus attenuates adiposity in DicerCKO mice. Furthermore, loss of miR-103 causes strong upregulation of the PI3K-Akt-mTOR pathway in vitro and its application into the ARC of the Dicer-deficient mice both reverses upregulation of Pik3cg, the mRNA encoding the catalytic subunit p110γ of the PI3K complex, and attenuates the hyperphagic obesity. Our data demonstrate in vivo the crucial role of neuronal microRNAs in the control of energy homeostasis.
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Caron A, Baraboi ED, Laplante M, Richard D. DEP domain-containing mTOR-interacting protein in the rat brain: Distribution of expression and potential implication. J Comp Neurol 2014; 523:93-107. [DOI: 10.1002/cne.23668] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 08/15/2014] [Accepted: 08/18/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Alexandre Caron
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
| | - Elena-Dana Baraboi
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
| | - Mathieu Laplante
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
| | - Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Québec; Université Laval; Quebec Quebec G1V 4G5 Canada
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Knight ZA, Schmidt SF, Birsoy K, Tan K, Friedman JM. A critical role for mTORC1 in erythropoiesis and anemia. eLife 2014; 3:e01913. [PMID: 25201874 PMCID: PMC4179304 DOI: 10.7554/elife.01913] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 09/04/2014] [Indexed: 12/31/2022] Open
Abstract
Red blood cells (RBC) must coordinate their rate of growth and proliferation with the availability of nutrients, such as iron, but the signaling mechanisms that link the nutritional state to RBC growth are incompletely understood. We performed a screen for cell types that have high levels of signaling through mTORC1, a protein kinase that couples nutrient availability to cell growth. This screen revealed that reticulocytes show high levels of phosphorylated ribosomal protein S6, a downstream target of mTORC1. We found that mTORC1 activity in RBCs is regulated by dietary iron and that genetic activation or inhibition of mTORC1 results in macrocytic or microcytic anemia, respectively. Finally, ATP competitive mTOR inhibitors reduced RBC proliferation and were lethal after treatment with phenylhydrazine, an inducer of hemolysis. These results identify the mTORC1 pathway as a critical regulator of RBC growth and proliferation and establish that perturbations in this pathway result in anemia. DOI:http://dx.doi.org/10.7554/eLife.01913.001 To multiply and grow, cells need to create more of the molecules—such as proteins—that make up their structure. This only happens if the cell has a good supply of the nutrients used to build the proteins. Red blood cells are particularly sensitive to the supply of nutrients, especially iron, which is a key component of the hemoglobin molecules that enable the cells to transport oxygen around the body. A lack of iron can lead to a shortage of red blood cells and a condition called anemia. People with mild forms of anemia may feel tired or weak, but more severe forms of anemia can cause heart problems and even death. A protein called mTOR forms part of a protein complex that helps alert the cells of many different organisms to the presence of nutrients. mTOR can add phosphate groups to ribosomes—the molecular machines that translate molecules of mRNA to build proteins. In 2012, researchers developed a technique called Phospho-Trap that can isolate these phosphorylated ribosomes from cells. Cells with an activated mTOR complex express more mTOR protein and in turn have more ribosomes that are modified. Examining the mRNA molecules associated with these ribosomes can reveal which proteins are produced in greater amounts in these cells. Previous experiments using Phospho-Trap found the proteins that make up hemoglobin in unexpectedly high amounts in the mouse brain. Now, Knight et al.—and other researchers involved in the 2012 work—have established that the hemoglobin was not coming from the brain cells but from immature red blood cells circulating within the brain. These immature blood cells were found to have a highly active mTOR complex that promotes the production of hemoglobin and new blood cells. Using genetic techniques in mice, Knight et al. found that the mTOR complex can cause anemia if it is underactive or overactive. Underactive mTOR complexes cause a type of anemia that produces small red blood cells and is usually triggered by a lack of iron. This made sense because mTOR is known to regulate both protein production and cell size. Boosting the activity of the mTOR complex leads to a type of anemia in which the cells are much larger than normal, and which is normally associated with inadequate amounts of folate and B12 vitamins. When Knight et al. gave mice a drug that inhibits the mTOR protein, the mice developed anemia that resolved when the treatment stopped. However, mice that were given the mTOR inhibitor at the same time as a drug that destroys red blood cells, all died within days. Clinical trials are currently testing mTOR inhibitors as a possible cancer treatment; however, a common side effect of chemotherapy is that it stops new red blood cells being produced. Knight et al. suggest that the red blood cells of patients in these clinical trials must be closely monitored before deciding whether to continue the treatment further. DOI:http://dx.doi.org/10.7554/eLife.01913.002
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Affiliation(s)
- Zachary A Knight
- Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Sarah F Schmidt
- Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Kivanc Birsoy
- Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Keith Tan
- Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Jeffrey M Friedman
- Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
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Kjell J, Codeluppi S, Josephson A, Abrams MB. Spatial and cellular characterization of mTORC1 activation after spinal cord injury reveals biphasic increase mainly attributed to microglia/macrophages. Brain Pathol 2014; 24:557-67. [PMID: 24576152 PMCID: PMC4347463 DOI: 10.1111/bpa.12135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 02/17/2014] [Indexed: 01/07/2023] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is an intracellular kinase complex that regulates energy homeostasis and transcription. Modulation of mTORC1 has proven beneficial in experimental spinal cord injury, making this molecular target a candidate for therapeutic intervention in spinal cord injury. However, both inactivation and activation of mTORC1 have been reported beneficial for recovery. To obtain a more complete picture of mTORC1 activity, we aimed to characterize the spatiotemporal activation pattern of mTORC1 and identify activation in particular cell types after contusion spinal cord injury in rats. To be able to provide a spatial characterization of mTORC1 activation, we monitored activation of downstream target S6. We found robust mTORC1 activation both at the site of injury and in spinal segments rostral and caudal to the injury. There was constitutive mTORC1 activation in neurons that was biphasically reduced caudally after injury. We found biphasic mTORC1 activation in glial cells, primarily activated microglia/macrophages. Furthermore, we found mTORC1 activation in proliferating cells, suggesting this may be a function affected by mTORC1 modulation. Our results reveal potential windows of opportunity for therapeutic interference with mTORC1 signaling and immune cells as targets for inhibition of mTORC1 in spinal cord injury.
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Affiliation(s)
- Jacob Kjell
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Hurtado-Carneiro V, Roncero I, Egger SS, Wenger RH, Blazquez E, Sanz C, Alvarez E. PAS kinase is a nutrient and energy sensor in hypothalamic areas required for the normal function of AMPK and mTOR/S6K1. Mol Neurobiol 2014; 50:314-26. [PMID: 24445950 DOI: 10.1007/s12035-013-8630-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/24/2013] [Indexed: 12/14/2022]
Abstract
The complications caused by overweight, obesity and type 2 diabetes are one of the main problems that increase morbidity and mortality in developed countries. Hypothalamic metabolic sensors play an important role in the control of feeding and energy homeostasis. PAS kinase (PASK) is a nutrient sensor proposed as a regulator of glucose metabolism and cellular energy. The role of PASK might be similar to other known metabolic sensors, such as AMP-activated protein kinase (AMPK) and the mammalian target of rapamycin (mTOR). PASK-deficient mice resist diet-induced obesity. We have recently reported that AMPK and mTOR/S6K1 pathways are regulated in the ventromedial and lateral hypothalamus in response to nutritional states, being modulated by anorexigenic glucagon-like peptide-1 (GLP-1)/exendin-4 in lean and obese rats. We identified PASK in hypothalamic areas, and its expression was regulated under fasting/re-feeding conditions and modulated by exendin-4. Furthermore, PASK-deficient mice have an impaired activation response of AMPK and mTOR/S6K1 pathways. Thus, hypothalamic AMPK and S6K1 were highly activated under fasted/re-fed conditions. Additionally, in this study, we have observed that the exendin-4 regulatory effect in the activity of metabolic sensors was lost in PASK-deficient mice, and the anorexigenic properties of exendin-4 were significantly reduced, suggesting that PASK could be a mediator in the GLP-1 signalling pathway. Our data indicated that the PASK function could be critical for preserving the nutrient effect on AMPK and mTOR/S6K1 pathways and maintain the regulatory role of exendin-4 in food intake. Some of the antidiabetogenic effects of exendin-4 might be modulated through these processes.
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Affiliation(s)
- Verónica Hurtado-Carneiro
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Complutense University, Plaza S. Ramón y Cajal, s/n, Madrid, 28040, Spain,
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Stevanovic D, Trajkovic V, Müller-Lühlhoff S, Brandt E, Abplanalp W, Bumke-Vogt C, Liehl B, Wiedmer P, Janjetovic K, Starcevic V, Pfeiffer AFH, Al-Hasani H, Tschöp MH, Castañeda TR. Ghrelin-induced food intake and adiposity depend on central mTORC1/S6K1 signaling. Mol Cell Endocrinol 2013; 381:280-90. [PMID: 23994018 DOI: 10.1016/j.mce.2013.08.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 07/25/2013] [Accepted: 08/19/2013] [Indexed: 10/26/2022]
Abstract
Signaling through the mammalian target of rapamycin complex 1 (mTORC1) and its effectors the S6-kinases (S6K) in the hypothalamus is thought to be involved in nutrient sensing and control of food intake. Given the anatomical proximity of this pathway to circuits for the hormone ghrelin, we investigated the potential role of the mTORC1/S6K pathway in mediating the metabolic effects of ghrelin. We found that ghrelin promoted phosphorylation of S6K1 in the mouse hypothalamic cell line N-41 and in the rat hypothalamus after intracerebroventricular administration. Rapamycin, an inhibitor of mTORC1, suppressed ghrelin-induced phosphorylation of hypothalamic S6K1 and increased food intake and insulin in rats. Chronic peripheral administration of ghrelin induced a significant increase in body weight, fat mass and food efficiency in wild-type and S6K2-knockout but not in S6K1-knockout mice. We therefore propose that ghrelin-induced hyperphagia, adiposity and insulin secretion are controlled by a central nervous system involving the mTORC1/S6K1 pathway.
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Affiliation(s)
- Darko Stevanovic
- Department of Clinical Nutrition, German Institute of Human Nutrition, Potsdam Rehbrücke, Germany; Institute of Physiology, School of Medicine, University of Belgrade, Serbia
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Delporte C. Structure and physiological actions of ghrelin. SCIENTIFICA 2013; 2013:518909. [PMID: 24381790 PMCID: PMC3863518 DOI: 10.1155/2013/518909] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/10/2013] [Indexed: 05/30/2023]
Abstract
Ghrelin is a gastric peptide hormone, discovered as being the endogenous ligand of growth hormone secretagogue receptor. Ghrelin is a 28 amino acid peptide presenting a unique n-octanoylation modification on its serine in position 3, catalyzed by ghrelin O-acyl transferase. Ghrelin is mainly produced by a subset of stomach cells and also by the hypothalamus, the pituitary, and other tissues. Transcriptional, translational, and posttranslational processes generate ghrelin and ghrelin-related peptides. Homo- and heterodimers of growth hormone secretagogue receptor, and as yet unidentified receptors, are assumed to mediate the biological effects of acyl ghrelin and desacyl ghrelin, respectively. Ghrelin exerts wide physiological actions throughout the body, including growth hormone secretion, appetite and food intake, gastric secretion and gastrointestinal motility, glucose homeostasis, cardiovascular functions, anti-inflammatory functions, reproductive functions, and bone formation. This review focuses on presenting the current understanding of ghrelin and growth hormone secretagogue receptor biology, as well as the main physiological effects of ghrelin.
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Affiliation(s)
- Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Université Libre de Bruxelles, 808 Route de Lennik, Bat G/E-CP611, 1070 Brussels, Belgium
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Guzmán-Quevedo O, Da Silva Aragão R, Pérez García G, Matos RJB, de Sa Braga Oliveira A, de Castro RM, Bolaños-Jiménez F. Impaired hypothalamic mTOR activation in the adult rat offspring born to mothers fed a low-protein diet. PLoS One 2013; 8:e74990. [PMID: 24040371 PMCID: PMC3767644 DOI: 10.1371/journal.pone.0074990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 08/08/2013] [Indexed: 12/23/2022] Open
Abstract
Several epidemiological and experimental studies have clearly established that maternal malnutrition induces a high risk of developing obesity and related metabolic diseases in the offspring. To determine if altered nutrient sensing might underlie this enhanced disease susceptibility, here we examined the effects of perinatal protein restriction on the activation of the nutrient sensor mTOR in response to acute variations in the nutritional status of the organism. Female Wistar rats were fed isocaloric diets containing either 17% protein (control) or 8% protein (PR) throughout pregnancy and lactation. At weaning offspring received standard chow and at 4 months of age the effects of fasting or fasting plus re-feeding on the phosphorylation levels of mTOR and its downstream target S6 ribosomal protein (rpS6) in the hypothalamus were assessed by immuno-fluorescence and western blot. Under ad libitum feeding conditions, PR rats exhibited decreased mTOR and rpS6 phosphorylation in the arcuate (ARC) and ventromedial (VMH) hypothalamic nuclei. Moreover, the phosphorylation of mTOR and rpS6 in these hypothalamic nuclei decreased with fasting in control but not in PR animals. Conversely, PR animals exhibited enhanced number of pmTOR imunostained cells in the paraventricular nucleus (PVN) and fasting decreased the activation of mTOR in the PVN of malnourished but not of control rats. These alterations occurred at a developmental stage at which perinatally-undernourished animals do not show yet obesity or glucose intolerance. Collectively, our observations suggest that altered hypothalamic nutrient sensing in response to an inadequate foetal and neonatal energetic environment is one of the basic mechanisms of the developmental programming of metabolic disorders and might play a causing role in the development of the metabolic syndrome induced by malnutrition during early life.
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Affiliation(s)
- Omar Guzmán-Quevedo
- Unité Mixte de recherche 1280 Physiologie des Adaptations Nutritionnelles, Institut National de la Recherche Agronomique, Nantes, France
- Université de Nantes, Nantes Atlantique Université, Nantes, France
| | - Raquel Da Silva Aragão
- Unité Mixte de recherche 1280 Physiologie des Adaptations Nutritionnelles, Institut National de la Recherche Agronomique, Nantes, France
- Université de Nantes, Nantes Atlantique Université, Nantes, France
- Departamento de Nutrição, Centro de Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Georgina Pérez García
- Unité Mixte de recherche 1280 Physiologie des Adaptations Nutritionnelles, Institut National de la Recherche Agronomique, Nantes, France
- Université de Nantes, Nantes Atlantique Université, Nantes, France
| | - Rhowena J. B. Matos
- Núcleo de Educação Física e Ciências do Esporte, Universidade Federal de Pernambuco, Vitória de Santo Antão, Pernambuco, Brazil
| | - André de Sa Braga Oliveira
- Unité Mixte de recherche 1280 Physiologie des Adaptations Nutritionnelles, Institut National de la Recherche Agronomique, Nantes, France
- Université de Nantes, Nantes Atlantique Université, Nantes, France
- Departamento de Nutrição, Centro de Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Raul Manhães de Castro
- Departamento de Nutrição, Centro de Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Francisco Bolaños-Jiménez
- Unité Mixte de recherche 1280 Physiologie des Adaptations Nutritionnelles, Institut National de la Recherche Agronomique, Nantes, France
- Université de Nantes, Nantes Atlantique Université, Nantes, France
- * E-mail:
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40
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Modulation of AgRP-neuronal function by SOCS3 as an initiating event in diet-induced hypothalamic leptin resistance. Proc Natl Acad Sci U S A 2013; 110:E697-706. [PMID: 23386726 DOI: 10.1073/pnas.1218284110] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chronic consumption of a fat-rich diet leads to attenuation of leptin signaling in hypothalamic neurons, a hallmark feature of cellular leptin resistance. To date, little is known about the temporal and spatial dysregulation of neuronal function under conditions of nutrient excess. We show that agouti-related protein (AgRP)-expressing neurons precede proopiomelanocortin neurons in developing diet-induced cellular leptin resistance. High-fat diet-induced up-regulation of suppressor of cytokine signaling-3 (SOCS3) occurs in AgRP neurons before proopiomelanocortin and other hypothalamic neurons. SOCS3 expression in AgRP neurons increases after 2 d of high-fat feeding, but reduces after switching to a low-fat diet for 1 d. Consistently, transgenic overexpression of SOCS3 in AgRP neurons produces metabolic phenotypes resembling those observed after short-term high-fat feeding. We further show that AgRP neurons are the predominant cell type situated outside the blood-brain barrier in the mediobasal hypothalamus. AgRP neurons are more responsive to low levels of circulating leptin, but they are also more prone to development of leptin resistance in response to a small increase in blood leptin concentrations. Collectively, these results suggest that AgRP neurons are able to sense slight changes in plasma metabolic signals, allowing them to serve as first-line responders to fluctuation of energy intake. Furthermore, modulation of SOCS3 expression in AgRP neurons may play a dynamic and physiological role in metabolic fine tuning in response to short-term changes of nutritional status.
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41
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Abstract
The central melanocortin system plays an essential role in the regulation of energy metabolism. Key to this regulation are the responses of neurons expressing proopiomelanocortin (POMC) and agouti-related protein (AgRP) to blood-borne metabolic signals. Recent evidence has demonstrated that POMC and AgRP neurons are not simply mirror opposites of each other in function and responsiveness to metabolic signals, nor are they exclusively first-order neurons. These neurons act as central transceivers, integrating both hormonal and neural signals, and then transmitting this information to peripheral tissues via the autonomic nervous system to coordinate whole-body energy metabolism. This review focuses on most recent developments obtained from rodent studies on the function, metabolic regulation, and circuitry of the central melanocortin system.
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Affiliation(s)
- James P. Warne
- Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Allison W. Xu
- Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA
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42
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Abstract
The mammalian brain is composed of thousands of interacting neural cell types. Systematic approaches to establish the molecular identity of functional populations of neurons would advance our understanding of neural mechanisms controlling behavior. Here, we show that ribosomal protein S6, a structural component of the ribosome, becomes phosphorylated in neurons activated by a wide range of stimuli. We show that these phosphorylated ribosomes can be captured from mouse brain homogenates, thereby enriching directly for the mRNAs expressed in discrete subpopulations of activated cells. We use this approach to identify neurons in the hypothalamus regulated by changes in salt balance or food availability. We show that galanin neurons are activated by fasting and that prodynorphin neurons restrain food intake during scheduled feeding. These studies identify elements of the neural circuit that controls food intake and illustrate how the activity-dependent capture of cell-type-specific transcripts can elucidate the functional organization of a complex tissue.
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43
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Yang SB, Tien AC, Boddupalli G, Xu AW, Jan YN, Jan LY. Rapamycin ameliorates age-dependent obesity associated with increased mTOR signaling in hypothalamic POMC neurons. Neuron 2012; 75:425-36. [PMID: 22884327 DOI: 10.1016/j.neuron.2012.03.043] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2012] [Indexed: 01/08/2023]
Abstract
VIDEO ABSTRACT The prevalence of obesity in older people is the leading cause of metabolic syndromes. Central neurons serving as homeostatic sensors for body-weight control include hypothalamic neurons that express pro-opiomelanocortin (POMC) or neuropeptide-Y (NPY) and agouti-related protein (AgRP). Here, we report an age-dependent increase of mammalian target of rapamycin (mTOR) signaling in POMC neurons that elevates the ATP-sensitive potassium (K(ATP)) channel activity cell-autonomously to silence POMC neurons. Systemic or intracerebral administration of the mTOR inhibitor rapamycin causes weight loss in old mice. Intracerebral rapamycin infusion into old mice enhances the excitability and neurite projection of POMC neurons, thereby causing a reduction of food intake and body weight. Conversely, young mice lacking the mTOR-negative regulator TSC1 in POMC neurons, but not those lacking TSC1 in NPY/AgRP neurons, were obese. Our study reveals that an increase in mTOR signaling in hypothalamic POMC neurons contributes to age-dependent obesity.
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Affiliation(s)
- Shi-Bing Yang
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
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Hypothalamic mTOR signaling mediates the orexigenic action of ghrelin. PLoS One 2012; 7:e46923. [PMID: 23056530 PMCID: PMC3467268 DOI: 10.1371/journal.pone.0046923] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/06/2012] [Indexed: 12/20/2022] Open
Abstract
Current evidence suggests that ghrelin, a stomach derived peptide, exerts its orexigenic action through specific modulation of Sirtuin1 (SIRT1)/p53 and AMP-activated protein kinase (AMPK) pathways, which ultimately increase the expression of agouti-related protein (AgRP) and neuropeptide Y (NPY) in the arcuate nucleus of the hypothalamus (ARC). However, there is a paucity of data about the possible action of ghrelin on alternative metabolic pathways at this level. Here, we demonstrate that ghrelin elicits a marked upregulation of the hypothalamic mammalian target of rapamycin (mTOR) signaling pathway. Of note, central inhibition of mTOR signaling with rapamycin decreased ghrelin’s orexigenic action and normalized the mRNA expression of AgRP and NPY, as well as their key downstream transcription factors, namely cAMP response-element binding protein (pCREB) and forkhead box O1 (FoxO1, total and phosphorylated). Taken together, these data indicate that, in addition to previous reported mechanisms, ghrelin also promotes feeding through modulation of hypothalamic mTOR pathway.
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45
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Xia T, Cheng Y, Zhang Q, Xiao F, Liu B, Chen S, Guo F. S6K1 in the central nervous system regulates energy expenditure via MC4R/CRH pathways in response to deprivation of an essential amino acid. Diabetes 2012; 61:2461-71. [PMID: 22787141 PMCID: PMC3447917 DOI: 10.2337/db11-1278] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
It is well established that the central nervous system (CNS), especially the hypothalamus, plays an important role in regulating energy homeostasis and lipid metabolism. We have previously shown that hypothalamic corticotropin-releasing hormone (CRH) is critical for stimulating fat loss in response to dietary leucine deprivation. The molecular mechanisms underlying the CNS regulation of leucine deprivation-stimulated fat loss are, however, still largely unknown. Here, we used intracerebroventricular injection of adenoviral vectors to identify a novel role for hypothalamic p70 S6 kinase 1 (S6K1), a major downstream effector of the kinase mammalian target of rapamycin, in leucine deprivation stimulation of energy expenditure. Furthermore, we show that the effect of hypothalamic S6K1 is mediated by modulation of Crh expression in a melanocortin-4 receptor-dependent manner. Taken together, our studies provide a new perspective for understanding the regulation of energy expenditure by the CNS and the importance of cross-talk between nutritional control and regulation of endocrine signals.
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Pinilla L, Aguilar E, Dieguez C, Millar RP, Tena-Sempere M. Kisspeptins and Reproduction: Physiological Roles and Regulatory Mechanisms. Physiol Rev 2012; 92:1235-316. [DOI: 10.1152/physrev.00037.2010] [Citation(s) in RCA: 529] [Impact Index Per Article: 44.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Procreation is essential for survival of species. Not surprisingly, complex neuronal networks have evolved to mediate the diverse internal and external environmental inputs that regulate reproduction in vertebrates. Ultimately, these regulatory factors impinge, directly or indirectly, on a final common pathway, the neurons producing the gonadotropin-releasing hormone (GnRH), which stimulates pituitary gonadotropin secretion and thereby gonadal function. Compelling evidence, accumulated in the last few years, has revealed that kisspeptins, a family of neuropeptides encoded by the Kiss1 gene and produced mainly by neuronal clusters at discrete hypothalamic nuclei, are pivotal upstream regulators of GnRH neurons. As such, kisspeptins have emerged as important gatekeepers of key aspects of reproductive maturation and function, from sexual differentiation of the brain and puberty onset to adult regulation of gonadotropin secretion and the metabolic control of fertility. This review aims to provide a comprehensive account of the state-of-the-art in the field of kisspeptin physiology by covering in-depth the consensus knowledge on the major molecular features, biological effects, and mechanisms of action of kisspeptins in mammals and, to a lesser extent, in nonmammalian vertebrates. This review will also address unsolved and contentious issues to set the scene for future research challenges in the area. By doing so, we aim to endow the reader with a critical and updated view of the physiological roles and potential translational relevance of kisspeptins in the integral control of reproductive function.
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Affiliation(s)
- Leonor Pinilla
- Department of Cell Biology, Physiology and Immunology, University of Córdoba; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III; and Instituto Maimónides de Investigaciones Biomédicas, Córdoba, Spain; Department of Physiology, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain; and Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Enrique Aguilar
- Department of Cell Biology, Physiology and Immunology, University of Córdoba; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III; and Instituto Maimónides de Investigaciones Biomédicas, Córdoba, Spain; Department of Physiology, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain; and Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Carlos Dieguez
- Department of Cell Biology, Physiology and Immunology, University of Córdoba; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III; and Instituto Maimónides de Investigaciones Biomédicas, Córdoba, Spain; Department of Physiology, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain; and Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Robert P. Millar
- Department of Cell Biology, Physiology and Immunology, University of Córdoba; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III; and Instituto Maimónides de Investigaciones Biomédicas, Córdoba, Spain; Department of Physiology, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain; and Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Manuel Tena-Sempere
- Department of Cell Biology, Physiology and Immunology, University of Córdoba; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III; and Instituto Maimónides de Investigaciones Biomédicas, Córdoba, Spain; Department of Physiology, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain; and Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom
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47
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Watterson KR, Bestow D, Gallagher J, Hamilton DL, Ashford FB, Meakin PJ, Ashford MLJ. Anorexigenic and orexigenic hormone modulation of mammalian target of rapamycin complex 1 activity and the regulation of hypothalamic agouti-related protein mRNA expression. Neurosignals 2012; 21:28-41. [PMID: 22456226 PMCID: PMC3704126 DOI: 10.1159/000334144] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 09/30/2011] [Indexed: 12/16/2022] Open
Abstract
Activation of mammalian target of rapamycin 1 (mTORC1) by nutrients, insulin and leptin leads to appetite suppression (anorexia). Contrastingly, increased AMP-activated protein kinase (AMPK) activity by ghrelin promotes appetite (orexia). However, the interplay between these mechanisms remains poorly defined. The relationship between the anorexigenic hormones, insulin and leptin, and the orexigenic hormone, ghrelin, on mTORC1 signalling was examined using S6 kinase phosphorylation as a marker for changes in mTORC1 activity in mouse hypothalamic GT1-7 cells. Additionally, the contribution of AMPK and mTORC1 signalling in relation to insulin-, leptin- and ghrelin-driven alterations to mouse hypothalamic agouti-related protein (AgRP) mRNA levels was examined. Insulin and leptin increase mTORC1 activity in a phosphoinositide-3-kinase (PI3K)- and protein kinase B (PKB)-dependent manner, compared to vehicle controls, whereas increasing AMPK activity inhibits mTORC1 activity and blocks the actions of the anorexigenic hormones. Ghrelin mediates an AMPK-dependent decrease in mTORC1 activity and increases hypothalamic AgRP mRNA levels, the latter effect being prevented by insulin in an mTORC1-dependent manner. In conclusion, mTORC1 acts as an integration node in hypothalamic neurons for hormone-derived PI3K and AMPK signalling and mediates at least part of the assimilated output of anorexigenic and orexigenic hormone actions in the hypothalamus.
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Affiliation(s)
- Kenneth R Watterson
- Medical Research Institute, Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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48
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Melnik BC. Excessive Leucine-mTORC1-Signalling of Cow Milk-Based Infant Formula: The Missing Link to Understand Early Childhood Obesity. J Obes 2012; 2012:197653. [PMID: 22523661 PMCID: PMC3317169 DOI: 10.1155/2012/197653] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Accepted: 01/09/2012] [Indexed: 01/22/2023] Open
Abstract
Increased protein supply by feeding cow-milk-based infant formula in comparison to lower protein content of human milk is a well-recognized major risk factor of childhood obesity. However, there is yet no conclusive biochemical concept explaining the mechanisms of formula-induced childhood obesity. It is the intention of this article to provide the biochemical link between leucine-mediated signalling of mammalian milk proteins and adipogenesis as well as early adipogenic programming. Leucine has been identified as the predominant signal transducer of mammalian milk, which stimulates the nutrient-sensitive kinase mammalian target of rapamycin complex 1 (mTORC1). Leucine thus functions as a maternal-neonatal relay for mTORC1-dependent neonatal β-cell proliferation and insulin secretion. The mTORC1 target S6K1 plays a pivotal role in stimulation of mesenchymal stem cells to differentiate into adipocytes and to induce insulin resistance. It is of most critical concern that infant formulas provide higher amounts of leucine in comparison to human milk. Exaggerated leucine-mediated mTORC1-S6K1 signalling induced by infant formulas may thus explain increased adipogenesis and generation of lifelong elevated adipocyte numbers. Attenuation of mTORC1 signalling of infant formula by leucine restriction to physiologic lower levels of human milk offers a great chance for the prevention of childhood obesity and obesity-related metabolic diseases.
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Affiliation(s)
- Bodo C. Melnik
- Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabrück, Sedanstrasse 115, 49090 Osnabrück, Germany
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49
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Castañeda TR, Abplanalp W, Um SH, Pfluger PT, Schrott B, Brown K, Grant E, Carnevalli L, Benoit SC, Morgan DA, Gilham D, Hui DY, Rahmouni K, Thomas G, Kozma SC, Clegg DJ, Tschöp MH. Metabolic control by S6 kinases depends on dietary lipids. PLoS One 2012; 7:e32631. [PMID: 22412899 PMCID: PMC3296718 DOI: 10.1371/journal.pone.0032631] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 01/28/2012] [Indexed: 11/19/2022] Open
Abstract
Targeted deletion of S6 kinase (S6K) 1 in mice leads to higher energy expenditure and improved glucose metabolism. However, the molecular mechanisms controlling these effects remain to be fully elucidated. Here, we analyze the potential role of dietary lipids in regulating the mTORC1/S6K system. Analysis of S6K phosphorylation in vivo and in vitro showed that dietary lipids activate S6K, and this effect is not dependent upon amino acids. Comparison of male mice lacking S6K1 and 2 (S6K-dko) with wt controls showed that S6K-dko mice are protected against obesity and glucose intolerance induced by a high-fat diet. S6K-dko mice fed a high-fat diet had increased energy expenditure, improved glucose tolerance, lower fat mass gain, and changes in markers of lipid metabolism. Importantly, however, these metabolic phenotypes were dependent upon dietary lipids, with no such effects observed in S6K-dko mice fed a fat-free diet. These changes appear to be mediated via modulation of cellular metabolism in skeletal muscle, as shown by the expression of genes involved in energy metabolism. Taken together, our results suggest that the metabolic functions of S6K in vivo play a key role as a molecular interface connecting dietary lipids to the endogenous control of energy metabolism.
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Affiliation(s)
- Tamara R. Castañeda
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Düsseldorf, Germany
| | - William Abplanalp
- Metabolic Disease Institute, Division of Endocrinology, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Sung Hee Um
- Department of Molecular Oncogenesis, Metabolic Disease Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Paul T. Pfluger
- HelmholtzZentrum München, German Research Center for Environmental Health (GmbH), Neuherberg/Munich, Germany
| | - Brigitte Schrott
- Metabolic Disease Institute, Division of Endocrinology, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Kimberly Brown
- Metabolic Disease Institute, Division of Endocrinology, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Erin Grant
- Metabolic Disease Institute, Division of Endocrinology, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Larissa Carnevalli
- Heidelberg Institute for Stem Cell Technology and Experimental Medicine (HI-STEM), Germany Division of Stem Cells and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Stephen C. Benoit
- Metabolic Disease Institute, Division of Endocrinology, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Donald A. Morgan
- Department of Internal Medicine, College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Dean Gilham
- Resverlogix Corporation (TSX:RVX), NW Calgary, Alberta, Canada
| | - David Y. Hui
- Department of Pathology, Centre of Arteriosclerosis Studies, Metabolic Disease Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Kamal Rahmouni
- Department of Internal Medicine, College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - George Thomas
- Department of Molecular Oncogenesis, Metabolic Disease Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Sara C. Kozma
- Department of Molecular Oncogenesis, Metabolic Disease Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Deborah J. Clegg
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Matthias H. Tschöp
- HelmholtzZentrum München, German Research Center for Environmental Health (GmbH), Neuherberg/Munich, Germany
- * E-mail:
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50
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Varela L, Martínez-Sánchez N, Gallego R, Vázquez MJ, Roa J, Gándara M, Schoenmakers E, Nogueiras R, Chatterjee K, Tena-Sempere M, Diéguez C, López M. Hypothalamic mTOR pathway mediates thyroid hormone-induced hyperphagia in hyperthyroidism. J Pathol 2012; 227:209-22. [PMID: 22294347 DOI: 10.1002/path.3984] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Revised: 12/15/2011] [Accepted: 12/22/2011] [Indexed: 11/08/2022]
Abstract
Hyperthyroidism is characterized in rats by increased energy expenditure and marked hyperphagia. Alterations of thermogenesis linked to hyperthyroidism are associated with dysregulation of hypothalamic AMPK and fatty acid metabolism; however, the central mechanisms mediating hyperthyroidism-induced hyperphagia remain largely unclear. Here, we demonstrate that hyperthyroid rats exhibit marked up-regulation of the hypothalamic mammalian target of rapamycin (mTOR) signalling pathway associated with increased mRNA levels of agouti-related protein (AgRP) and neuropeptide Y (NPY), and decreased mRNA levels of pro-opiomelanocortin (POMC) in the arcuate nucleus of the hypothalamus (ARC), an area where mTOR co-localizes with thyroid hormone receptor-α (TRα). Central administration of thyroid hormone (T3) or genetic activation of thyroid hormone signalling in the ARC recapitulated hyperthyroidism effects on feeding and the mTOR pathway. In turn, central inhibition of mTOR signalling with rapamycin in hyperthyroid rats reversed hyperphagia and normalized the expression of ARC-derived neuropeptides, resulting in substantial body weight loss. The data indicate that in the hyperthyroid state, increased feeding is associated with thyroid hormone-induced up-regulation of mTOR signalling. Furthermore, our findings that different neuronal modulations influence food intake and energy expenditure in hyperthyroidism pave the way for a more rational design of specific and selective therapeutic compounds aimed at reversing the metabolic consequences of this disease.
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Affiliation(s)
- Luis Varela
- Department of Physiology, School of Medicine-CIMUS, University of Santiago de Compostela, Instituto de Investigación Sanitaria, Santiago de Compostela (A Coruña) 15782, Spain
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