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García-Cruz VM, Arias C. Palmitic Acid Induces Posttranslational Modifications of Tau Protein in Alzheimer's Disease-Related Epitopes and Increases Intraneuronal Tau Levels. Mol Neurobiol 2024; 61:5129-5141. [PMID: 38167971 PMCID: PMC11249523 DOI: 10.1007/s12035-023-03886-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 12/14/2023] [Indexed: 01/05/2024]
Abstract
Metabolic diseases derived from an unhealthy lifestyle have been linked with an increased risk for developing cognitive impairment and even Alzheimer's disease (AD). Although high consumption of saturated fatty acids such as palmitic acid (PA) has been associated with the development of obesity and type II diabetes, the mechanisms connecting elevated neuronal PA levels and increased AD marker expression remain unclear. Among other effects, PA induces insulin resistance, increases intracellular calcium and reactive oxygen species (ROS) production, and reduces the NAD+/NADH ratio, resulting in decreased activity of the deacetylase Sirtuin1 (SIRT1) in neurons. These mechanisms may affect signaling pathways that impact the posttranslational modifications (PTMs) of the tau protein. To analyze the role played by PA in inducing the phosphorylation and acetylation of tau, we examined PTM changes in human tau in differentiated neurons from human neuroblastoma cells. We found changes in the phosphorylation state of several AD-related sites, namely, S199/202 and S214, that were mediated by a mechanism associated with the dysregulated activity of the kinases GSK3β and mTOR. PA also increased the acetylation of residue K280 and elevated total tau level after long exposure time. These findings provide information about the mechanisms by which saturated fatty acids cause tau PTMs that are similar to those observed in association with AD biochemical changes.
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Affiliation(s)
- Valeria Melissa García-Cruz
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, CDMX, 04510, México
| | - Clorinda Arias
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, CDMX, 04510, México.
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2
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Zhang Y, Dong T, Wang M. Lipidomic landscape of lipokines in adipose tissue derived extracellular vesicles. Front Mol Biosci 2023; 10:1281244. [PMID: 38028559 PMCID: PMC10644713 DOI: 10.3389/fmolb.2023.1281244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction: Adipose tissue-derived extracellular vesicles (EVs-AT) are recognized as critical mediators of metabolic alterations in obesity-related diseases. However, few studies have focused on the role of lipids within EVs-AT in the development of obesity-related diseases. Methods: In this study, we performed a targeted lipidomic analysis to compare the lipidome of EVs secreted by inguinal white adipose tissue (EVs-iWAT), epididymal white adipose tissue (EVs-eWAT), and interscapular brown adipose tissue (EVs-BAT) in lean and obese mice. Results: We uncovered a comprehensive lipidomic map, revealing the diversity and specific lipid sorting in EVs-iWAT, EVs-eWAT, and EVs-BAT in obesity. Biological function analyses suggested that lipids encapsulated within EVs-AT of obese individuals might correlate with metabolism, pro-inflammatory response, and insulin resistance. These effects were particularly pronounced in EVs-eWAT and EVs-BAT. Conclusion: Our findings indicated that EVs-AT serves as novel carriers for lipokines, thereby mediating the biological functions of EVs-AT. This study holds promise for the identification of new biomarkers for obesity-related diseases and the development of new strategies to combat metabolic diseases.
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Affiliation(s)
- Yan Zhang
- Department of Oral and Maxillofacial Surgery, Tianjin Stomatological Hospital, School of Medicine, Nankai University, Tianjin, China
- Key Laboratory of Bioactive Materials (Ministry of Education), State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Oral and Maxillofacial Function Reconstruction, Tianjin, China
| | - Tingyan Dong
- Key Laboratory of Bioactive Materials (Ministry of Education), State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Oral and Maxillofacial Function Reconstruction, Tianjin, China
| | - Muyao Wang
- Department of Oral and Maxillofacial Surgery, Tianjin Stomatological Hospital, School of Medicine, Nankai University, Tianjin, China
- Key Laboratory of Bioactive Materials (Ministry of Education), State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
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3
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Wen J, Wang Y, Wang C, Yuan M, Chen F, Zou Q, Cai Z, Zhao B. Dietary High-Fat Promotes Cognitive Impairment by Suppressing Mitophagy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2023; 2023:4822767. [PMID: 36718278 PMCID: PMC9884172 DOI: 10.1155/2023/4822767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/06/2023] [Accepted: 01/11/2023] [Indexed: 01/22/2023]
Abstract
Dietary habits contribute to the characteristics of Alzheimer's disease (AD) and cognitive impairment, which are partly induced by the accumulation of hyperphosphorylated Tau, a microtubule-associated protein. In mice, a fat-rich diet facilitates cognitive dysfunction. However, the mechanism by which dietary fat damages the brain remains unclear. In this study, 13-month-old C57BL/6 mice were fed a normal or high-fat diet (HFD) for 6 months. Neuro-2a cells were incubated with the normal medium or palmitic acid (200 μM). Spatial memory was assessed utilizing a behavioral test. Further, western blotting and immunofluorescence techniques were used to determine the levels of mitophagy-related proteins. The synaptic morphology and phosphorylation of Tau proteins were also evaluated. Administration of HFD decreased the expression of synaptophysin and brain-derived neurotrophic factor expression, leading to significant damage to neurons. Tau protein hyperphosphorylation was detected at different loci both in vivo and in vitro. Significantly impaired learning and memory abilities, accompanied by impaired mitophagy-related processes, were observed in mice fed with HFD as compared to mice fed with normal food. In conclusion, high fatty-acid intake hinders mitophagy and upregulates Tau protein phosphorylation, including age-related synaptic dysfunction, which leads to cognitive decline.
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Affiliation(s)
- Jie Wen
- Department and Institute of Neurology, Guangdong Medical University, Zhanjiang, Guangdong 524001, China
- Guangdong Key Laboratory of Aging-Related Cardiac and Cerebral Diseases, Zhanjiang, Guangdong 524001, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
| | - Yangyang Wang
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
| | - Chuanling Wang
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
- Chongqing Medical University, Yuzhong District, Chongqing 400016, China
| | - Minghao Yuan
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
- Chongqing Medical University, Yuzhong District, Chongqing 400016, China
| | - Fei Chen
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
- Chongqing Medical University, Yuzhong District, Chongqing 400016, China
| | - Qian Zou
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
| | - Zhiyou Cai
- Chongqing Key Laboratory of Neurodegenerative Diseases, Yuzhong District, Chongqing 400013, China
- Department of Neurology, Chongqing General Hospital, Yuzhong District, Chongqing 400013, China
| | - Bin Zhao
- Department and Institute of Neurology, Guangdong Medical University, Zhanjiang, Guangdong 524001, China
- Guangdong Key Laboratory of Aging-Related Cardiac and Cerebral Diseases, Zhanjiang, Guangdong 524001, China
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4
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Jin BY, Kim HJ, Oh MJ, Ha NH, Jeong YT, Choi SH, Lee JS, Kim NH, Kim DH. Metformin acts as a dual glucose regulator in mouse brain. Front Pharmacol 2023; 14:1108660. [PMID: 37153803 PMCID: PMC10157063 DOI: 10.3389/fphar.2023.1108660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 04/12/2023] [Indexed: 05/10/2023] Open
Abstract
Aims: Metformin improves glucose regulation through various mechanisms in the periphery. Our previous study revealed that oral intake of metformin activates several brain regions, including the hypothalamus, and directly activates hypothalamic S6 kinase in mice. In this study, we aimed to identify the direct effects of metformin on glucose regulation in the brain. Materials and methods: We investigated the role of metformin in peripheral glucose regulation by directly administering metformin intracerebroventricularly in mice. The effect of centrally administered metformin (central metformin) on peripheral glucose regulation was evaluated by oral or intraperitoneal glucose, insulin, and pyruvate tolerance tests. Hepatic gluconeogenesis and gastric emptying were assessed to elucidate the underlying mechanisms. Liver-specific and systemic sympathetic denervation were performed. Results: Central metformin improved the glycemic response to oral glucose load in mice compared to that in the control group, and worsened the response to intraperitoneal glucose load, indicating its dual role in peripheral glucose regulation. It lowered the ability of insulin to decrease serum glucose levels and worsened the glycemic response to pyruvate load relative to the control group. Furthermore, it increased the expression of hepatic G6pc and decreased the phosphorylation of STAT3, suggesting that central metformin increased hepatic glucose production. The effect was mediated by sympathetic nervous system activation. In contrast, it induced a significant delay in gastric emptying in mice, suggesting its potent role in suppressing intestinal glucose absorption. Conclusion: Central metformin improves glucose tolerance by delaying gastric emptying through the brain-gut axis, but at the same time worsens it by increasing hepatic glucose production via the brain-liver axis. However, with its ordinary intake, central metformin may effectively enhance its glucose-lowering effect through the brain-gut axis, which could surpass its effect on glucose regulation via the brain-liver axis.
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Affiliation(s)
- Bo-Yeong Jin
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medicine, Korea University, Seoul, Republic of Korea
| | - Hyun-Ju Kim
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
| | - Mi-Jeong Oh
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medicine, Korea University, Seoul, Republic of Korea
| | - Na-Hee Ha
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medicine, Korea University, Seoul, Republic of Korea
| | - Yong Taek Jeong
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medicine, Korea University, Seoul, Republic of Korea
| | - Sang-Hyun Choi
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
| | - Jun-Seok Lee
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
| | - Nam Hoon Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Dong-Hoon Kim
- Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medicine, Korea University, Seoul, Republic of Korea
- *Correspondence: Dong-Hoon Kim,
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Zakharova IO, Bayunova LV, Derkach KV, Ilyasov IO, Morina IY, Shpakov AO, Avrova NF. Effects of Intranasally Administered Insulin and Gangliosides on Hypothalamic Signaling and Expression of Hepatic Gluconeogenesis Genes in Rats with Type 2 Diabetes Mellitus. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022060072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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6
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Oliveira LDC, Morais GP, Ropelle ER, de Moura LP, Cintra DE, Pauli JR, de Freitas EC, Rorato R, da Silva ASR. Using Intermittent Fasting as a Non-pharmacological Strategy to Alleviate Obesity-Induced Hypothalamic Molecular Pathway Disruption. Front Nutr 2022; 9:858320. [PMID: 35445066 PMCID: PMC9014844 DOI: 10.3389/fnut.2022.858320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 02/25/2022] [Indexed: 12/18/2022] Open
Abstract
Intermittent fasting (IF) is a popular intervention used to fight overweight/obesity. This condition is accompanied by hypothalamic inflammation, limiting the proper signaling of molecular pathways, with consequent dysregulation of food intake and energy homeostasis. This mini-review explored the therapeutic modulation potential of IF regarding the disruption of these molecular pathways. IF seems to modulate inflammatory pathways in the brain, which may also be correlated with the brain-microbiota axis, improving hypothalamic signaling of leptin and insulin, and inducing the autophagic pathway in hypothalamic neurons, contributing to weight loss in obesity. Evidence also suggests that when an IF protocol is performed without respecting the circadian cycle, it can lead to dysregulation in the expression of circadian cycle regulatory genes, with potential health damage. In conclusion, IF may have the potential to be an adjuvant treatment to improve the reestablishment of hypothalamic responses in obesity.
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Affiliation(s)
- Luciana da Costa Oliveira
- Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Gustavo Paroschi Morais
- Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Eduardo R. Ropelle
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - Leandro P. de Moura
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - Dennys E. Cintra
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - José R. Pauli
- Laboratory of Molecular Biology of Exercise, School of Applied Sciences, University of Campinas, São Paulo, Brazil
| | - Ellen C. de Freitas
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | - Rodrigo Rorato
- Postgraduate Program in Molecular Biology, Laboratory of Stress Neuroendocrinology, Department of Biophysics, Paulista Medical School, Federal University of São Paulo, São Paulo, Brazil
- Rodrigo Rorato,
| | - Adelino Sanchez R. da Silva
- Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
- *Correspondence: Adelino Sanchez R. da Silva,
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7
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Yang L, Zhang Z, Wang D, Jiang Y, Liu Y. Targeting mTOR Signaling in Type 2 Diabetes Mellitus and Diabetes Complications. Curr Drug Targets 2022; 23:692-710. [PMID: 35021971 DOI: 10.2174/1389450123666220111115528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/21/2021] [Accepted: 12/01/2021] [Indexed: 11/22/2022]
Abstract
The mechanistic target of rapamycin (mTOR) is a pivotal regulator of cell metabolism and growth. In the form of two different multi-protein complexes, mTORC1 and mTORC2, mTOR integrates cellular energy, nutrient and hormonal signals to regulate cellular metabolic homeostasis. In type 2 diabetes mellitus (T2DM) aberrant mTOR signaling underlies its pathological conditions and end-organ complications. Substantial evidence suggests that two mTOR-mediated signaling schemes, mTORC1-p70S6 kinase 1 (S6K1) and mTORC2-protein kinase B (AKT), play a critical role in insulin sensitivity and that their dysfunction contributes to development of T2DM. This review summaries our current understanding of the role of mTOR signaling in T2DM and its associated complications, as well as the potential use of mTOR inhibitors in treatment of T2DM.
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Affiliation(s)
- Lin Yang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Zhixin Zhang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Doudou Wang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Ying Liu
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
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8
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Scherer T, Sakamoto K, Buettner C. Brain insulin signalling in metabolic homeostasis and disease. Nat Rev Endocrinol 2021; 17:468-483. [PMID: 34108679 DOI: 10.1038/s41574-021-00498-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/22/2021] [Indexed: 02/06/2023]
Abstract
Insulin signalling in the central nervous system regulates energy homeostasis by controlling metabolism in several organs and by coordinating organ crosstalk. Studies performed in rodents, non-human primates and humans over more than five decades using intracerebroventricular, direct hypothalamic or intranasal application of insulin provide evidence that brain insulin action might reduce food intake and, more importantly, regulates energy homeostasis by orchestrating nutrient partitioning. This Review discusses the metabolic pathways that are under the control of brain insulin action and explains how brain insulin resistance contributes to metabolic disease in obesity, the metabolic syndrome and type 2 diabetes mellitus.
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Affiliation(s)
- Thomas Scherer
- Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
| | - Kenichi Sakamoto
- Division of Endocrinology, Metabolism & Nutrition, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - Christoph Buettner
- Division of Endocrinology, Metabolism & Nutrition, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
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9
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Burillo J, Marqués P, Jiménez B, González-Blanco C, Benito M, Guillén C. Insulin Resistance and Diabetes Mellitus in Alzheimer's Disease. Cells 2021; 10:1236. [PMID: 34069890 PMCID: PMC8157600 DOI: 10.3390/cells10051236] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/11/2021] [Accepted: 05/13/2021] [Indexed: 12/12/2022] Open
Abstract
Type 2 diabetes mellitus is a progressive disease that is characterized by the appearance of insulin resistance. The term insulin resistance is very wide and could affect different proteins involved in insulin signaling, as well as other mechanisms. In this review, we have analyzed the main molecular mechanisms that could be involved in the connection between type 2 diabetes and neurodegeneration, in general, and more specifically with the appearance of Alzheimer's disease. We have studied, in more detail, the different processes involved, such as inflammation, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction.
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Affiliation(s)
- Jesús Burillo
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Patricia Marqués
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Beatriz Jiménez
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Carlos González-Blanco
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Manuel Benito
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Carlos Guillén
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
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10
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Edem EE, Nathaniel BU, Nebo KE, Obisesan AO, Olabiyi AA, Akinluyi ET, Ishola AO. Lactobacillus plantarum mitigates sexual-reproductive deficits by modulating insulin receptor expression in the hypothalamic-pituitary-testicular axis of hyperinsulinemic mice. Drug Metab Pers Ther 2021; 36:321-336. [PMID: 34002580 DOI: 10.1515/dmpt-2021-1000195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 04/05/2021] [Indexed: 01/15/2023]
Abstract
OBJECTIVES Hyperinsulinemia increases the risk factor of diabetes and infertility at a manifold. Lactobacillus plantarum has several medical significances with limited reports. Hence, this study assessed the effect of L. plantarum on sexual-reproductive functions and distribution of insulin receptors in the hypothalamic-pituitary-testicular axis of hyperinsulinemic mice. METHODS Forty male adult mice were divided into five groups as follows: control, high-fat diet (HFD) + streptozotocin (STZ), therapeutic, co-administration group type 1 (CO-AD) and probiotics. They were either simultaneously exposed to an HFD and L. plantarum treatment for 28 days with a dose of STZ injection to induce hyperinsulinemia on day 28 or treated with L. plantarum for 14 days, and following induction of hyperinsulinemia. Mice were subjected to a sexual behavioural test and thereafter sacrificed under euthanasia condition. Blood, brain and testes were collected for biochemical and immunohistochemical assays. RESULTS Treatment with L. plantarum ameliorated reproductive hormones activity disruption, sexual behavioural defects, antioxidant imbalance, insulin dysregulation and lipid metabolism dysfunction following exposure to HFD + STZ when compared to the hyperinsulinemic untreated mice. CONCLUSIONS Taken together, data from this study reveal that L. plantarum abrogated hyperinsulinemia-induced male sexual and reproductive deficits by modulating antioxidant status, lipid metabolism and insulin signalling in the hypothalamic-pituitary-testicular axis of mice.
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Affiliation(s)
- Edem Ekpenyong Edem
- Department of Anatomy, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
| | - Blessing Uyo Nathaniel
- Department of Anatomy, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
| | - Kate Eberechukwu Nebo
- Department of Anatomy, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
| | - Abiola Oluwatosin Obisesan
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
| | - Ayodeji Augustine Olabiyi
- Department of Medical Biochemistry, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
| | - Elizabeth Toyin Akinluyi
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
| | - Azeez Olakunle Ishola
- Department of Anatomy, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria
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11
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Li RJW, Batchuluun B, Zhang SY, Abraham MA, Wang B, Lim YM, Yue JTY, Lam TKT. Nutrient infusion in the dorsal vagal complex controls hepatic lipid and glucose metabolism in rats. iScience 2021; 24:102366. [PMID: 33870148 PMCID: PMC8044434 DOI: 10.1016/j.isci.2021.102366] [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: 10/20/2020] [Revised: 02/08/2021] [Accepted: 03/24/2021] [Indexed: 11/22/2022] Open
Abstract
Hypothalamic regulation of lipid and glucose homeostasis is emerging, but whether the dorsal vagal complex (DVC) senses nutrients and regulates hepatic nutrient metabolism remains unclear. Here, we found in rats DVC oleic acid infusion suppressed hepatic secretion of triglyceride-rich very-low-density lipoprotein (VLDL-TG), which was disrupted by inhibiting DVC long-chain fatty acyl-CoA synthetase that in parallel disturbed lipid homeostasis during intravenous lipid infusion. DVC glucose infusion elevated local glucose levels similarly as intravenous glucose infusion and suppressed hepatic glucose production. This was independent of lactate metabolism as inhibiting lactate dehydrogenase failed to disrupt glucose sensing and neither could DVC lactate infusion recapitulate glucose effect. DVC oleic acid and glucose infusion failed to lower VLDL-TG secretion and glucose production in high-fat fed rats, while inhibiting DVC farnesoid X receptor enhanced oleic acid but not glucose sensing. Thus, an impairment of DVC nutrient sensing may lead to the disruption of lipid and glucose homeostasis in metabolic syndrome. DVC oleic acid infusion lowers hepatic secretion of VLDL-TG in chow but not HF rats Inhibition of ACSL in the DVC negates lipid sensing DVC glucose infusion lowers hepatic glucose production in chow but not HF rats Inhibition of FXR in the DVC enhances oleic acid but not glucose sensing in HF rats
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Affiliation(s)
- Rosa J W Li
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Battsetseg Batchuluun
- Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Song-Yang Zhang
- Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Mona A Abraham
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Beini Wang
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Yu-Mi Lim
- Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada.,Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, Republic of Korea
| | - Jessica T Y Yue
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Tony K T Lam
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada.,Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.,Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada
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12
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Abstract
Cells metabolize nutrients for biosynthetic and bioenergetic needs to fuel growth and proliferation. The uptake of nutrients from the environment and their intracellular metabolism is a highly controlled process that involves cross talk between growth signaling and metabolic pathways. Despite constant fluctuations in nutrient availability and environmental signals, normal cells restore metabolic homeostasis to maintain cellular functions and prevent disease. A central signaling molecule that integrates growth with metabolism is the mechanistic target of rapamycin (mTOR). mTOR is a protein kinase that responds to levels of nutrients and growth signals. mTOR forms two protein complexes, mTORC1, which is sensitive to rapamycin, and mTORC2, which is not directly inhibited by this drug. Rapamycin has facilitated the discovery of the various functions of mTORC1 in metabolism. Genetic models that disrupt either mTORC1 or mTORC2 have expanded our knowledge of their cellular, tissue, as well as systemic functions in metabolism. Nevertheless, our knowledge of the regulation and functions of mTORC2, particularly in metabolism, has lagged behind. Since mTOR is an important target for cancer, aging, and other metabolism-related pathologies, understanding the distinct and overlapping regulation and functions of the two mTOR complexes is vital for the development of more effective therapeutic strategies. This review discusses the key discoveries and recent findings on the regulation and metabolic functions of the mTOR complexes. We highlight findings from cancer models but also discuss other examples of the mTOR-mediated metabolic reprogramming occurring in stem and immune cells, type 2 diabetes/obesity, neurodegenerative disorders, and aging.
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Affiliation(s)
- Angelia Szwed
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Eugene Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
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13
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Abstract
Blood glucose and insulin homeostasis is disrupted during the progression of type 2 diabetes. Insulin levels and action are regulated by both peripheral and central responses that involve the intestine and microbiome. The intestine and its microbiota process nutrients and generate molecules that influence blood glucose and insulin. Peripheral insulin regulation is regulated by gut-segment-dependent nutrient sensing and microbial factors such as short-chain fatty acids and bile acids that engage G-protein-coupled receptors. Innate immune sensing of gut-derived bacterial cell wall components and lipopolysaccharides also alter insulin homeostasis. These bacterial metabolites and postbiotics influence insulin secretion and insulin clearance in part by altering endocrine responses such as glucagon-like peptide-1. Gut-derived bacterial factors can promote inflammation and insulin resistance, but other postbiotics can be insulin sensitizers. In parallel, activation of small intestinal sirtuin 1 increases insulin sensitivity by reversing high fat-induced hypothalamic insulin resistance through a gut-brain neuronal axis, whereas high fat-feeding alters small intestinal microbiome and increases taurochenodeoxycholic acid in the plasma and the dorsal vagal complex to induce insulin resistance. In summary, emerging evidence indicates that intestinal molecular signaling involving nutrient sensing and the host-microbe symbiosis alters insulin homeostasis and action. Gut-derived host endocrine and paracrine factors as well as microbial metabolites act on the liver, pancreas, and the brain, and in parallel on the gut-brain neuronal axis. Understanding common nodes of peripheral and central insulin homeostasis and action may reveal new ways to target the intestinal host-microbe relationship in obesity, metabolic disease, and type 2 diabetes.
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Affiliation(s)
- Jonathan D Schertzer
- Department of Biochemistry and Biomedical Sciences, Farncombe Family Digestive Health Research Institute, Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, UHN, Toronto, Ontario, Canada
- Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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14
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Gannaban RB, NamKoong C, Ruiz HH, Choi HJ, Shin AC. Central Regulation of Branched-Chain Amino Acids Is Mediated by AgRP Neurons. Diabetes 2021; 70:62-75. [PMID: 33115827 PMCID: PMC7881842 DOI: 10.2337/db20-0510] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/20/2020] [Indexed: 11/13/2022]
Abstract
Circulating branched-chain amino acids (BCAAs) are elevated in obesity and diabetes, and recent studies support a causal role for BCAAs in insulin resistance and defective glycemic control. The physiological mechanisms underlying BCAA regulation are poorly understood. Here we show that insulin signaling in the mediobasal hypothalamus (MBH) of rats is mandatory for lowering plasma BCAAs, most probably by inducing hepatic BCAA catabolism. Insulin receptor deletion only in agouti-related protein (AgRP)-expressing neurons (AgRP neurons) in the MBH impaired hepatic BCAA breakdown and suppression of plasma BCAAs during hyperinsulinemic clamps in mice. In support of this, chemogenetic stimulation of AgRP neurons in the absence of food significantly raised plasma BCAAs and impaired hepatic BCAA degradation. A prolonged fasting or ghrelin treatment recapitulated designer receptors exclusively activated by designer drugs-induced activation of AgRP neurons and increased plasma BCAAs. Acute stimulation of vagal motor neurons in the dorsal motor nucleus was sufficient to decrease plasma BCAAs. Notably, elevated plasma BCAAs were associated with impaired glucose homeostasis. These findings suggest a critical role of insulin signaling in AgRP neurons for BCAA regulation and raise the possibility that this control may be mediated primarily via vagal outflow. Furthermore, our results provide an opportunity to closely examine the potential mechanistic link between central nervous system-driven BCAA control and glucose homeostasis.
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Affiliation(s)
- Ritchel B Gannaban
- Neurobiology of Nutrition Laboratory, Department of Nutritional Sciences, College of Human Sciences, Texas Tech University, Lubbock, TX
| | - Cherl NamKoong
- Division of Functional Neuroanatomy of Metabolism Regulation, Department of Biomedical Sciences, Seoul National University, Seoul, South Korea
| | - Henry H Ruiz
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University, New York, NY
| | - Hyung Jin Choi
- Division of Functional Neuroanatomy of Metabolism Regulation, Department of Biomedical Sciences, Seoul National University, Seoul, South Korea
| | - Andrew C Shin
- Neurobiology of Nutrition Laboratory, Department of Nutritional Sciences, College of Human Sciences, Texas Tech University, Lubbock, TX
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15
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Patel B, New LE, Griffiths JC, Deuchars J, Filippi BM. Inhibition of mitochondrial fission and iNOS in the dorsal vagal complex protects from overeating and weight gain. Mol Metab 2020; 43:101123. [PMID: 33227495 PMCID: PMC7753200 DOI: 10.1016/j.molmet.2020.101123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVES The dorsal vagal complex (DVC) senses insulin and controls glucose homeostasis, feeding behaviour and body weight. Three-days of high-fat diet (HFD) in rats are sufficient to induce insulin resistance in the DVC and impair its ability to regulate feeding behaviour. HFD-feeding is associated with increased dynamin-related protein 1 (Drp1)-dependent mitochondrial fission in the DVC. We investigated the effects that altered Drp1 activity in the DVC has on feeding behaviour. Additionally, we aimed to uncover the molecular events and the neuronal cell populations associated with DVC insulin sensing and resistance. METHODS Eight-week-old male Sprague Dawley rats received DVC stereotactic surgery for brain infusion to facilitate the localised administration of insulin or viruses to express mutated forms of Drp1 or to knockdown inducible nitric oxide synthase (iNOS) in the NTS of the DVC. High-Fat diet feeding was used to cause insulin resistance and obesity. RESULTS We showed that Drp1 activation in the DVC increases weight gain in rats and Drp1 inhibition in HFD-fed rats reduced food intake, weight gain and adipose tissue. Rats expressing active Drp1 in the DVC had higher levels of iNOS and knockdown of DVC iNOS in HFD-fed rats led to a reduction of food intake, weight gain and adipose tissue. Finally, inhibiting mitochondrial fission in DVC astrocytes was sufficient to protect rats from HFD-dependent insulin resistance, hyperphagia, weight gain and fat deposition. CONCLUSION We uncovered new molecular and cellular targets for brain regulation of whole-body metabolism, which could inform new strategies to combat obesity and diabetes.
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Affiliation(s)
- Bianca Patel
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Lauryn E New
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Joanne C Griffiths
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Jim Deuchars
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom
| | - Beatrice M Filippi
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, United Kingdom.
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16
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Haigh JL, New LE, Filippi BM. Mitochondrial Dynamics in the Brain Are Associated With Feeding, Glucose Homeostasis, and Whole-Body Metabolism. Front Endocrinol (Lausanne) 2020; 11:580879. [PMID: 33240218 PMCID: PMC7680879 DOI: 10.3389/fendo.2020.580879] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
The brain is responsible for maintaining whole-body energy homeostasis by changing energy input and availability. The hypothalamus and dorsal vagal complex (DVC) are the primary sites of metabolic control, able to sense both hormones and nutrients and adapt metabolism accordingly. The mitochondria respond to the level of nutrient availability by fusion or fission to maintain energy homeostasis; however, these processes can be disrupted by metabolic diseases including obesity and type II diabetes (T2D). Mitochondrial dynamics are crucial in the development and maintenance of obesity and T2D, playing a role in the control of glucose homeostasis and whole-body metabolism across neurons and glia in the hypothalamus and DVC.
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Affiliation(s)
| | | | - Beatrice M. Filippi
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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17
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Reho JJ, Guo DF, Rahmouni K. Mechanistic Target of Rapamycin Complex 1 Signaling Modulates Vascular Endothelial Function Through Reactive Oxygen Species. J Am Heart Assoc 2020; 8:e010662. [PMID: 31020916 PMCID: PMC6512105 DOI: 10.1161/jaha.118.010662] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background The mechanistic target of rapamycin complex 1 (mTORC1) is an important intracellular energy sensor that regulates gene expression and protein synthesis through its downstream signaling components, the S6‐kinase and the ribosomal S6 protein. Recently, signaling arising from mTORC1 has been implicated in regulation of the cardiovascular system with implications for disease. Here, we examined the contribution of mTORC1 signaling to the regulation of vascular function. Methods and Results Activation of mTORC1 pathway in aortic rings with leucine or an adenoviral vector expressing a constitutively active S6‐kinase reduces endothelial‐dependent vasorelaxation in an mTORC1‐dependent manner without affecting smooth muscle relaxation responses. Moreover, activation of mTORC1 signaling in endothelial cells increases reactive oxygen species (ROS) generation and ROS gene expression resulting in a pro‐oxidant gene environment. Blockade of ROS signaling with Tempol restores endothelial function in vascular rings with increased mTORC1 activity indicating a crucial interaction between mTORC1 and ROS signaling. We then tested the role of nuclear factor‐κB transcriptional complex in connecting mTORC1 and ROS signaling in endothelial cells. Blockade of inhibitor of nuclear factor κ‐B kinase subunit β activity with BMS‐345541 prevented the increased ROS generation associated with increased mTORC1 activity in endothelial cells but did not improve vascular endothelial function in aortic rings with increased mTORC1 and ROS signaling. Conclusions These results implicate mTORC1 as a critical molecular signaling hub in the vascular endothelium in mediating vascular endothelial function through modulation of ROS signaling.
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Affiliation(s)
- John J Reho
- 1 Department of Pharmacology University of Iowa Carver College of Medicine Iowa City IA
| | - Deng-Fu Guo
- 1 Department of Pharmacology University of Iowa Carver College of Medicine Iowa City IA
| | - Kamal Rahmouni
- 1 Department of Pharmacology University of Iowa Carver College of Medicine Iowa City IA.,2 Department of Internal Medicine University of Iowa Carver College of Medicine Iowa City IA.,3 Fraternal Order of Eagles Diabetes Research Center University of Iowa Iowa City IA
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18
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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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19
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Siddik MAB, Shin AC. Recent Progress on Branched-Chain Amino Acids in Obesity, Diabetes, and Beyond. Endocrinol Metab (Seoul) 2019; 34:234-246. [PMID: 31565875 PMCID: PMC6769348 DOI: 10.3803/enm.2019.34.3.234] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/16/2019] [Accepted: 09/21/2019] [Indexed: 12/22/2022] Open
Abstract
Branched-chain amino acids (BCAAs) are essential amino acids that are not synthesized in our body; thus, they need to be obtained from food. They have shown to provide many physiological and metabolic benefits such as stimulation of pancreatic insulin secretion, milk production, adipogenesis, and enhanced immune function, among others, mainly mediated by mammalian target of rapamycin (mTOR) signaling pathway. After identified as a reliable marker of obesity and type 2 diabetes in recent years, an increasing number of studies have surfaced implicating BCAAs in the pathophysiology of other diseases such as cancers, cardiovascular diseases, and even neurodegenerative disorders like Alzheimer's disease. Here we discuss the most recent progress and review studies highlighting both correlational and potentially causative role of BCAAs in the development of these disorders. Although we are just beginning to understand the intricate relationships between BCAAs and some of the most prevalent chronic diseases, current findings raise a possibility that they are linked by a similar putative mechanism.
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Affiliation(s)
- Md Abu Bakkar Siddik
- Department of Nutritional Sciences, College of Human Sciences, Texas Tech University, Lubbock, TX, USA
| | - Andrew C Shin
- Department of Nutritional Sciences, College of Human Sciences, Texas Tech University, Lubbock, TX, USA.
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20
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Molecular Mechanisms of Hypothalamic Insulin Resistance. Int J Mol Sci 2019; 20:ijms20061317. [PMID: 30875909 PMCID: PMC6471380 DOI: 10.3390/ijms20061317] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/07/2019] [Accepted: 03/13/2019] [Indexed: 02/06/2023] Open
Abstract
Insulin exists in the central nervous system, where it executes two important functions in the hypothalamus: the suppression of food intake and the improvement of glucose metabolism. Recent studies have shown that both are exerted robustly in rodents and humans. If intact, these functions exert beneficial effects on obesity and diabetes, respectively. Disruption of both occurs due to a condition known as hypothalamic insulin resistance, which is caused by obesity and the overconsumption of saturated fat. An enormous volume of literature addresses the molecular mechanisms of hypothalamic insulin resistance. IKKβ and JNK are major players in the inflammation pathway, which is activated by saturated fatty acids that induce hypothalamic insulin resistance. Two major tyrosine phosphatases, PTP-1B and TCPTP, are upregulated in chronic overeating. They dephosphorylate the insulin receptor and insulin receptor substrate proteins, resulting in hypothalamic insulin resistance. Prolonged hyperinsulinemia with excessive nutrition activates the mTOR/S6 kinase pathway, thereby enhancing IRS-1 serine phosphorylation to induce hypothalamic insulin resistance. Other mechanisms associated with this condition include hypothalamic gliosis and disturbed insulin transport into the central nervous system. Unveiling the precise molecular mechanisms involved in hypothalamic insulin resistance is important for developing new ways of treating obesity and type 2 diabetes.
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21
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Grandl G, Straub L, Rudigier C, Arnold M, Wueest S, Konrad D, Wolfrum C. Short-term feeding of a ketogenic diet induces more severe hepatic insulin resistance than an obesogenic high-fat diet. J Physiol 2018; 596:4597-4609. [PMID: 30089335 PMCID: PMC6166091 DOI: 10.1113/jp275173] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/18/2018] [Indexed: 11/25/2022] Open
Abstract
KEY POINTS A ketogenic diet is known to lead to weight loss and is considered metabolically healthy; however there are conflicting reports on its effect on hepatic insulin sensitivity. KD fed animals appear metabolically healthy in the fasted state after 3 days of dietary challenge, whereas obesogenic high-fat diet (HFD) fed animals show elevated insulin levels. A glucose challenge reveals that both KD and HFD fed animals are glucose intolerant. Glucose intolerance correlates with increased lipid oxidation and lower respiratory exchange ratio (RER); however, all animals respond to glucose injection with an increase in RER. Hyperinsulinaemic-euglycaemic clamps with double tracer show that the effect of KD is a result of hepatic insulin resistance and increased glucose output but not impaired glucose clearance or tissue glucose uptake in other tissues. ABSTRACT Despite being a relevant healthcare issue and heavily investigated, the aetiology of type 2 diabetes (T2D) is still incompletely understood. It is well established that increased endogenous glucose production (EGP) leads to a progressive increase in glucose levels, causing insulin resistance and eventual loss of glucose homeostasis. The consumption of high carbohydrate, high-fat, western style diet (HFD) is linked to the development of T2D and obesity, whereas the consumption of a low carbohydrate, high-fat, ketogenic diet (KD) is considered healthy. However, several days of carbohydrate restriction are known to cause selective hepatic insulin resistance. In the present study, we compare the effects of short-term HFD and KD feeding on glucose homeostasis in mice. We show that, even though KD fed animals appear to be healthy in the fasted state, they exhibit decreased glucose tolerance to a greater extent than HFD fed animals. Furthermore, we show that this effect originates from blunted suppression of hepatic glucose production by insulin, rather than impaired glucose clearance and tissue glucose uptake. These data suggest that the early effects of HFD consumption on EGP may be part of a normal physiological response to increased lipid intake and oxidation, and that systemic insulin resistance results from the addition of dietary glucose to EGP-derived glucose.
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Affiliation(s)
| | | | | | - Myrtha Arnold
- Physiology and Behavior LaboratoryETH ZürichSchwerzenbachSwitzerland
| | - Stephan Wueest
- Division of Pediatric Endocrinology and Diabetology
- Children's Research CenterUniversity Children's HospitalZurichSwitzerland
| | - Daniel Konrad
- Division of Pediatric Endocrinology and Diabetology
- Children's Research CenterUniversity Children's HospitalZurichSwitzerland
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22
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Sahu M, Anamthathmakula P, Sahu A. Hypothalamic PDE3B deficiency alters body weight and glucose homeostasis in mouse. J Endocrinol 2018; 239:93-105. [PMID: 30307157 PMCID: PMC6190684 DOI: 10.1530/joe-18-0304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Pharmacological studies have suggested hypothalamic phosphodiesterase-3B to mediate leptin and insulin action in regulation of energy homeostasis. Whereas Pde3b-null mice show altered energy homeostasis, it is unknown whether this is due to ablation of Pde3b in the hypothalamus. Thus, to address the functional significance of hypothalamic phosphodiesterase-3B, we used Pde3bflox/flox and Nkx2.1-Cre mice to generate Pde3b Nkx2.1KD mice that showed 50% reduction of phosphodiesterase-3B in the hypothalamus. To determine the effect of partial ablation of phosphodiesterase-3B in the hypothalamus on energy and glucose homeostasis, males and females were subjected to either a low- or high-fat diet for 19–21 weeks. Only female but not male Pde3b Nkx2.1KD mice on the low-fat diet showed increased body weight from 13 weeks onward with increased food intake, decreased fat pad weights and hypoleptinemia. Glucose tolerance was improved in high-fat diet-fed male Pde3b Nkx2.1KD mice in association with decreased phosphoenolpyruvate carboxykinase-1 and glucose-6-phosphatase mRNA levels in the liver. Also, insulin sensitivity was increased in male Pde3b Nkx2.1KD mice on the low-fat diet. Changes in body weight or in glucose homeostasis were not associated with any alteration in hypothalamic proopiomelanocortin, neuropepide Y and agouti-related peptide mRNA levels. These results suggest that partial loss of phosphodiesterase-3B in the hypothalamus produces a sex-specific response in body weight and glucose homeostasis, and support a role, at least in part, for hypothalamic phosphodiesterase-3B in regulation of energy and glucose homeostasis in mice.
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Affiliation(s)
- Maitrayee Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Prashanth Anamthathmakula
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Abhiram Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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23
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Ma Y, Ratnasabapathy R, Izzi-Engbeaya C, Nguyen-Tu MS, Richardson E, Hussain S, De Backer I, Holton C, Norton M, Carrat G, Schwappach B, Rutter GA, Dhillo WS, Gardiner J. Hypothalamic arcuate nucleus glucokinase regulates insulin secretion and glucose homeostasis. Diabetes Obes Metab 2018; 20:2246-2254. [PMID: 29748994 PMCID: PMC6099255 DOI: 10.1111/dom.13359] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 04/30/2018] [Accepted: 05/09/2018] [Indexed: 01/08/2023]
Abstract
AIMS To investigate the role of arcuate glucokinase (GK) in the regulation of glucose homeostasis. MATERIALS AND METHODS A recombinant adeno-associated virus expressing either GK or an antisense GK construct was used to alter GK activity specifically in the hypothalamic arcuate nucleus (arc). GK activity in this nucleus was also increased by stereotactic injection of the GK activator, compound A. The effect of altered arc GK activity on glucose homeostasis was subsequently investigated using glucose and insulin tolerance tests. RESULTS Increased GK activity specifically within the arc increased insulin secretion and improved glucose tolerance in rats during oral glucose tolerance tests. Decreased GK activity in this nucleus reduced insulin secretion and increased glucose levels during the same tests. Insulin sensitivity was not affected in either case. The effect of arc GK was maintained in a model of type 2 diabetes. CONCLUSIONS These results demonstrate a role for arc GK in systemic glucose homeostasis.
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Affiliation(s)
- Yue Ma
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Risheka Ratnasabapathy
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Chioma Izzi-Engbeaya
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Marie-Sophie Nguyen-Tu
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Errol Richardson
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Sufyan Hussain
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Ivan De Backer
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Christopher Holton
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Mariana Norton
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Gaelle Carrat
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Blanche Schwappach
- Department of Molecular Biology, Centre for Biochemistry and Molecular Cell Biology, Heart Research Centre Göttingen, University Medicine Göttingen, Göttingen, Germany
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Waljit S Dhillo
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - James Gardiner
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
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Huang X, Liu G, Guo J, Su Z. The PI3K/AKT pathway in obesity and type 2 diabetes. Int J Biol Sci 2018; 14:1483-1496. [PMID: 30263000 PMCID: PMC6158718 DOI: 10.7150/ijbs.27173] [Citation(s) in RCA: 838] [Impact Index Per Article: 139.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/10/2018] [Indexed: 02/06/2023] Open
Abstract
Obesity and type 2 diabetes mellitus are complicated metabolic diseases that affect multiple organs and are characterized by hyperglycaemia. Currently, stable and effective treatments for obesity and type 2 diabetes mellitus are not available. Therefore, the mechanisms leading to obesity and diabetes and more effective ways to treat obesity and diabetes should be identified. Based on accumulated evidences, the PI3K/AKT signalling pathway is required for normal metabolism due to its characteristics, and its imbalance leads to the development of obesity and type 2 diabetes mellitus. This review focuses on the role of PI3K/AKT signalling in the skeletal muscle, adipose tissue, liver, brain and pancreas, and discusses how this signalling pathway affects the development of the aforementioned diseases. We also summarize evidences for recently identified therapeutic targets of the PI3K/AKT pathway as treatments for obesity and type 2 diabetes mellitus. PI3K/AKT pathway damaged in various tissues of the body leads to obesity and type 2 diabetes as the result of insulin resistance, and in turn, insulin resistance exacerbates the PI3K/AKT pathway, forming a vicious circle.
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Affiliation(s)
- Xingjun Huang
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou (510006), China.,Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou (510006), China
| | - Guihua Liu
- Shenzhen Center for Disease Control and Prevention, 8 Longyuan Road, Nanshan District, Shenzhen (518055), China
| | - Jiao Guo
- Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou (510006), China
| | - Zhengquan Su
- Guangdong Engineering Research Center of Natural Products and New Drugs, Guangdong Provincial University Engineering Technology Research Center of Natural Products and Drugs, Guangdong Pharmaceutical University, Guangzhou (510006), China.,Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou (510006), China
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25
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Abraham MA, Rasti M, Bauer PV, Lam TKT. Leptin enhances hypothalamic lactate dehydrogenase A (LDHA)-dependent glucose sensing to lower glucose production in high-fat-fed rats. J Biol Chem 2018; 293:4159-4166. [PMID: 29374061 DOI: 10.1074/jbc.ra117.000838] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/10/2018] [Indexed: 01/15/2023] Open
Abstract
The responsiveness of glucose sensing per se to regulate whole-body glucose homeostasis is dependent on the ability of a rise in glucose to lower hepatic glucose production and increase peripheral glucose uptake in vivo In both rodents and humans, glucose sensing is lost in diabetes and obesity, but the site(s) of impairment remains elusive. Here, we first report that short-term high-fat feeding disrupts hypothalamic glucose sensing to lower glucose production in rats. Second, leptin administration into the hypothalamus of high-fat-fed rats restored hypothalamic glucose sensing to lower glucose production during a pancreatic (basal insulin)-euglycemic clamp and increased whole-body glucose tolerance during an intravenous glucose tolerance test. Finally, both chemical inhibition of hypothalamic lactate dehydrogenase (LDH) (achieved via hypothalamic LDH inhibitor oxamate infusion) and molecular knockdown of LDHA (achieved via hypothalamic lentiviral LDHA shRNA injection) negated the ability of hypothalamic leptin infusion to enhance glucose sensing to lower glucose production in high fat-fed rats. In summary, our findings illustrate that leptin enhances LDHA-dependent glucose sensing in the hypothalamus to lower glucose production in high-fat-fed rodents in vivo.
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Affiliation(s)
- Mona A Abraham
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada.,Departments of Physiology and
| | - Mozhgan Rasti
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada
| | - Paige V Bauer
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada.,Departments of Physiology and
| | - Tony K T Lam
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada, .,Departments of Physiology and.,Medicine, University of Toronto, Toronto M5S 1A8, Canada, and.,Banting and Best Diabetes Centre, University of Toronto, Toronto M5G 2C4, Canada
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Shin AC, Filatova N, Lindtner C, Chi T, Degann S, Oberlin D, Buettner C. Insulin Receptor Signaling in POMC, but Not AgRP, Neurons Controls Adipose Tissue Insulin Action. Diabetes 2017; 66:1560-1571. [PMID: 28385803 PMCID: PMC5440019 DOI: 10.2337/db16-1238] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 03/22/2017] [Indexed: 12/31/2022]
Abstract
Insulin is a key regulator of adipose tissue lipolysis, and impaired adipose tissue insulin action results in unrestrained lipolysis and lipotoxicity, which are hallmarks of the metabolic syndrome and diabetes. Insulin regulates adipose tissue metabolism through direct effects on adipocytes and through signaling in the central nervous system by dampening sympathetic outflow to the adipose tissue. Here we examined the role of insulin signaling in agouti-related protein (AgRP) and pro-opiomelanocortin (POMC) neurons in regulating hepatic and adipose tissue insulin action. Mice lacking the insulin receptor in AgRP neurons (AgRP IR KO) exhibited impaired hepatic insulin action because the ability of insulin to suppress hepatic glucose production (hGP) was reduced, but the ability of insulin to suppress lipolysis was unaltered. To the contrary, in POMC IR KO mice, insulin lowered hGP but failed to suppress adipose tissue lipolysis. High-fat diet equally worsened glucose tolerance in AgRP and POMC IR KO mice and their respective controls but increased hepatic triglyceride levels only in POMC IR KO mice, consistent with impaired lipolytic regulation resulting in fatty liver. These data suggest that although insulin signaling in AgRP neurons is important in regulating glucose metabolism, insulin signaling in POMC neurons controls adipose tissue lipolysis and prevents high-fat diet-induced hepatic steatosis.
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Affiliation(s)
- Andrew C Shin
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Nika Filatova
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Claudia Lindtner
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Tiffany Chi
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Seta Degann
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Douglas Oberlin
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Christoph Buettner
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
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Ruud J, Steculorum SM, Brüning JC. Neuronal control of peripheral insulin sensitivity and glucose metabolism. Nat Commun 2017; 8:15259. [PMID: 28469281 PMCID: PMC5418592 DOI: 10.1038/ncomms15259] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 03/14/2017] [Indexed: 12/19/2022] Open
Abstract
The central nervous system (CNS) has an important role in the regulation of peripheral insulin sensitivity and glucose homeostasis. Research in this dynamically developing field has progressed rapidly due to techniques allowing targeted transgenesis and neurocircuitry mapping, which have defined the primary responsive neurons, associated molecular mechanisms and downstream neurocircuitries and processes involved. Here we review the brain regions, neurons and molecular mechanisms by which the CNS controls peripheral glucose metabolism, particularly via regulation of liver, brown adipose tissue and pancreatic function, and highlight the potential implications of these regulatory pathways in type 2 diabetes and obesity. The brain controls peripheral glucose metabolism, for example by modulating hepatic gluconeogenesis or by regulating glucose uptake into brown adipose tissue. Here, the authors review the brain regions, neurons and molecular mechanisms involved in these processes, and discuss their relevance to disease.
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Affiliation(s)
- Johan Ruud
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924 Cologne, Germany
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Sophie M. Steculorum
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924 Cologne, Germany
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Jens C. Brüning
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
- Policlinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Kerpener Strasse 26, 50924 Cologne, Germany
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
- National Center for Diabetes Research (DZD), Ingolstädter Land Strasse 1, 85764 Neuherberg, Germany
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CCL5/RANTES contributes to hypothalamic insulin signaling for systemic insulin responsiveness through CCR5. Sci Rep 2016; 6:37659. [PMID: 27898058 PMCID: PMC5127185 DOI: 10.1038/srep37659] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/31/2016] [Indexed: 11/08/2022] Open
Abstract
Many neurodegenerative diseases are accompanied by metabolic disorders. CCL5/RANTES, and its receptor CCR5 are known to contribute to neuronal function as well as to metabolic disorders such as type 2 diabetes mellitus, obesity, atherosclerosis and metabolic changes after HIV infection. Herein, we found that the lack of CCR5 or CCL5 in mice impaired regulation of energy metabolism in hypothalamus. Immunostaining and co-immunoprecipitation revealed the specific expression of CCR5, associated with insulin receptors, in the hypothalamic arcuate nucleus (ARC). Both ex vivo stimulation and in vitro tissue culture studies demonstrated that the activation of insulin, and PI3K-Akt pathways were impaired in CCR5 and CCL5 deficient hypothalamus. The inhibitory phosphorylation of insulin response substrate-1 at Ser302 (IRS-1S302) but not IRS-2, by insulin was markedly increased in CCR5 and CCL5 deficient animals. Elevating CCR5/CCL5 activity induced GLUT4 membrane translocation and reduced phospho-IRS-1S302 through AMPKα-S6 Kinase. Blocking CCR5 using the antagonist, MetCCL5, abolished the de-phosphorylation of IRS-1S302 and insulin signal activation. In addition, intracerebroventricular delivery of MetCCL5 interrupted hypothalamic insulin signaling and elicited peripheral insulin responsiveness and glucose intolerance. Taken together, our data suggest that CCR5 regulates insulin signaling in hypothalamus which contributes to systemic insulin sensitivity and glucose metabolism.
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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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Caron A, Labbé SM, Mouchiroud M, Huard R, Lanfray D, Richard D, Laplante M. DEPTOR in POMC neurons affects liver metabolism but is dispensable for the regulation of energy balance. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1322-31. [PMID: 27097662 DOI: 10.1152/ajpregu.00549.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 04/18/2016] [Indexed: 11/22/2022]
Abstract
We have recently demonstrated that specific overexpression of DEP-domain containing mTOR-interacting protein (DEPTOR) in the mediobasal hypothalamus (MBH) protects mice against high-fat diet-induced obesity, revealing DEPTOR as a significant contributor to energy balance regulation. On the basis of evidence that DEPTOR is expressed in the proopiomelanocortin (POMC) neurons of the MBH, the present study aimed to investigate whether these neurons mediate the metabolic effects of DEPTOR. Here, we report that specific DEPTOR overexpression in POMC neurons does not recapitulate any of the phenotypes observed when the protein was overexpressed in the MBH. Unlike the previous model, mice overexpressing DEPTOR only in POMC neurons 1) did not show differences in feeding behavior, 2) did not exhibit changes in locomotion activity and oxygen consumption, 3) did not show an improvement in systemic glucose metabolism, and 4) were not resistant to high-fat diet-induced obesity. These results support the idea that other neuronal populations are responsible for these phenotypes. Nonetheless, we observed a mild elevation in fasting blood glucose, insulin resistance, and alterations in liver glucose and lipid homeostasis in mice overexpressing DEPTOR in POMC neurons. Taken together, these results show that DEPTOR overexpression in POMC neurons does not affect energy balance regulation but could modulate metabolism through a brain-liver connection.
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Affiliation(s)
- Alexandre Caron
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Sébastien M Labbé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Mathilde Mouchiroud
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Renaud Huard
- Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Damien Lanfray
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Mathieu Laplante
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Quebec, Canada; and Département de Médecine, Faculté de Médecine, Université Laval, Québec, Québec, Canada
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Sahu M, Anamthathmakula P, Sahu A. Hypothalamic Phosphodiesterase 3B Pathway Mediates Anorectic and Body Weight-Reducing Effects of Insulin in Male Mice. Neuroendocrinology 2016; 104:145-156. [PMID: 27002827 PMCID: PMC5035167 DOI: 10.1159/000445523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 03/17/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND Insulin action in the hypothalamus plays a critical role in the regulation of energy homeostasis, yet the intracellular signaling mechanisms mediating insulin action are incompletely understood. Although phosphodiesterase 3B (PDE3B) mediates insulin action in the adipose tissue and it is highly expressed in the hypothalamic areas implicated in energy homeostasis, its role, if any, in mediating insulin action in the hypothalamus is unknown. We tested the hypothesis that insulin action in the hypothalamus is mediated by PDE3B. METHODS Using enzymatic assay, we examined the effects of peripheral or central administration of insulin on hypothalamic PDE3B activity in adult mice. Western blotting and immunohistochemistry also examined p-Akt and p-STAT3 levels in the hypothalamus. Effects of leptin on these parameters were also compared. We injected cilostamide, a PDE3 inhibitor, prior to central injection of insulin and examined the 12- to 24-hour food intake and 24-hour body weight. Finally, we examined the effect of cilostamide on insulin-induced proopiomelanocortin (Pomc), neurotensin (Nt), neuropeptide Y (Npy) and agouti-related peptide (Agrp) gene expression in the hypothalamus by qPCR. RESULTS Peripheral or central injection of insulin significantly increased PDE3B activity in the hypothalamus in association with increased p-Akt levels but without any change in p-STAT3 levels. However, leptin-induced increase in PDE3B activity was associated with an increase in both p-Akt and p-STAT3 levels in the hypothalamus. Prior administration of cilostamide reversed the anorectic and body weight-reducing effects as well as stimulatory effect of insulin on hypothalamic Pomc mRNA levels. Insulin did not alter Nt, Npy and Agrp mRNA levels. CONCLUSION Insulin induction of hypothalamic PDE3B activity and the reversal of the anorectic and body weight-reducing effects and stimulatory effect of insulin on hypothalamic Pomc gene expression by cilostamide suggest that activation of PDE3B is a novel mechanism of insulin signaling in the hypothalamus.
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Affiliation(s)
- Maitrayee Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Prashanth Anamthathmakula
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Abhiram Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Emerging role of the brain in the homeostatic regulation of energy and glucose metabolism. Exp Mol Med 2016; 48:e216. [PMID: 26964832 PMCID: PMC4892882 DOI: 10.1038/emm.2016.4] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/07/2015] [Accepted: 12/09/2015] [Indexed: 12/12/2022] Open
Abstract
Accumulated evidence from genetic animal models suggests that the brain, particularly the hypothalamus, has a key role in the homeostatic regulation of energy and glucose metabolism. The brain integrates multiple metabolic inputs from the periphery through nutrients, gut-derived satiety signals and adiposity-related hormones. The brain modulates various aspects of metabolism, such as food intake, energy expenditure, insulin secretion, hepatic glucose production and glucose/fatty acid metabolism in adipose tissue and skeletal muscle. Highly coordinated interactions between the brain and peripheral metabolic organs are critical for the maintenance of energy and glucose homeostasis. Defective crosstalk between the brain and peripheral organs contributes to the development of obesity and type 2 diabetes. Here we comprehensively review the above topics, discussing the main findings related to the role of the brain in the homeostatic regulation of energy and glucose metabolism.
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Increased susceptibility to metabolic dysregulation in a mouse model of Alzheimer's disease is associated with impaired hypothalamic insulin signaling and elevated BCAA levels. Alzheimers Dement 2016; 12:851-61. [PMID: 26928090 DOI: 10.1016/j.jalz.2016.01.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 01/20/2016] [Accepted: 01/26/2016] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Epidemiologic studies have demonstrated an association between diabetes and dementia. Insulin signaling within the brain, in particular within the hypothalamus regulates carbohydrate, lipid, and branched chain amino acid (BCAA) metabolism in peripheral organs such as the liver and adipose tissue. We hypothesized that cerebral amyloidosis impairs central nervous system control of metabolism through disruption of insulin signaling in the hypothalamus, which dysregulates glucose and BCAA homeostasis resulting in increased susceptibility to diabetes. METHODS We examined whether APP/PS1 mice exhibit increased susceptibility to aging or high-fat diet (HFD)-induced metabolic impairment using metabolic phenotyping and insulin-signaling studies. RESULTS APP/PS1 mice were more susceptible to high-fat feeding and aging-induced metabolic dysregulation including disrupted BCAA homeostasis and exhibited impaired hypothalamic insulin signaling. DISCUSSION Our data suggest that AD pathology increases susceptibility to diabetes due to impaired hypothalamic insulin signaling, and that plasma BCAA levels could serve as a biomarker of hypothalamic insulin action in patients with AD.
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Abstract
Insulin controls hepatic glucose production (HGP) and maintains glucose homeostasis through the direct action of hepatic insulin receptors, as well as the indirect action of insulin receptors in the central nervous system. Insulin acts on insulin receptors in the hypothalamic arcuate nucleus, activates ATP-sensitive potassium channels in a phosphoinositide 3-kinase (PI3K)-dependent manner, induces hyperpolarization of the hypothalamic neurons, and regulates HGP via the vagus nerve. In the liver, central insulin action augments IL-6 expression in Kupffer cells and activates STAT3 transcription factors in hepatocytes. Activated STAT3 suppresses the gene expression of gluconeogenic enzymes, thereby reducing HGP. It has become evident that nutrients such as glucose, fatty acids, and amino acids act upon the hypothalamus together with insulin, affecting HGP. On the other hand, HGP control by central insulin action is impeded in obesity and impeded by insulin resistance due to disturbance of PI3K signaling and inflammation in the hypothalamus or inhibition of STAT3 signaling in the liver. Although the mechanism of control of hepatic gluconeogenic gene expression by central insulin action is conserved across species, its importance in human glucose metabolism has not been made entirely clear and its elucidation is anticipated in the future.
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Affiliation(s)
- Hiroshi Inoue
- Metabolism and Nutrition Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa 920-8641, Japan
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35
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Mediobasal hypothalamic overexpression of DEPTOR protects against high-fat diet-induced obesity. Mol Metab 2015; 5:102-112. [PMID: 26909318 PMCID: PMC4735664 DOI: 10.1016/j.molmet.2015.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 11/18/2015] [Accepted: 11/25/2015] [Indexed: 01/29/2023] Open
Abstract
Background/Objective The mechanistic target of rapamycin (mTOR) is a serine–threonine kinase that functions into distinct protein complexes (mTORC1 and mTORC2) that regulate energy homeostasis. DEP-domain containing mTOR-interacting protein (DEPTOR) is part of these complexes and is known to dampen mTORC1 function, consequently reducing mTORC1 negative feedbacks and promoting insulin signaling and Akt/PKB activation in several models. Recently, we observed that DEPTOR is expressed in several structures of the brain including the mediobasal hypothalamus (MBH), a region that regulates energy balance. Whether DEPTOR in the MBH plays a functional role in regulating energy balance and hypothalamic insulin signaling has never been tested. Methods We have generated a novel conditional transgenic mouse model based on the Cre-LoxP system allowing targeted overexpression of DEPTOR. Mice overexpressing DEPTOR in the MBH were subjected to a metabolic phenotyping and MBH insulin signaling was evaluated. Results We first report that systemic (brain and periphery) overexpression of DEPTOR prevents high-fat diet-induced obesity, improves glucose metabolism and protects against hepatic steatosis. These phenotypes were associated with a reduction in food intake and feed efficiency and an elevation in oxygen consumption. Strikingly, specific overexpression of DEPTOR in the MBH completely recapitulated these phenotypes. DEPTOR overexpression was associated with an increase in hypothalamic insulin signaling, as illustrated by elevated Akt/PKB activation. Conclusion Altogether, these results support a role for MBH DEPTOR in the regulation of energy balance and metabolism. Systemic (brain and peripheral) overexpression of DEPTOR promotes activity and improves glucose homeostasis. Systemic (brain and peripheral) overexpression of DEPTOR protects againts high-fat diet-induced obesity and metabolic alterations. Deptor is widely expressed in the mouse brain, with a high expression in the mediobasal hypothalamus (MBH), a key region of the brain that regulates energy balance. MBH-specific DEPTOR overexpression improves glucose metabolism and protects mice against obesity. MBH-specific DEPTOR overexpression promotes hypothalamic Akt/PKB signaling.
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36
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Paradoxical effect of rapamycin on inflammatory stress-induced insulin resistance in vitro and in vivo. Sci Rep 2015; 5:14959. [PMID: 26449763 PMCID: PMC4598825 DOI: 10.1038/srep14959] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/11/2015] [Indexed: 12/16/2022] Open
Abstract
Insulin resistance is closely related to inflammatory stress and the mammalian target of rapamycin/S6 kinase (mTOR/S6K) pathway. The present study investigated whether rapamycin, a specific inhibitor of mTOR, ameliorates inflammatory stress-induced insulin resistance in vitro and in vivo. We used tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) stimulation in HepG2 hepatocytes, C2C12 myoblasts and 3T3-L1 adipocytes and casein injection in C57BL/6J mice to induce inflammatory stress. Our results showed that inflammatory stress impairs insulin signaling by reducing the expression of total IRS-1, p-IRS-1 (tyr632), and p-AKT (ser473); it also activates the mTOR/S6K signaling pathway both in vitro and in vivo. In vitro, rapamycin treatment reversed inflammatory cytokine-stimulated IRS-1 serine phosphorylation, increased insulin signaling to AKT and enhanced glucose utilization. In vivo, rapamycin treatment also ameliorated the impaired insulin signaling induced by inflammatory stress, but it induced pancreatic β-cell apoptosis, reduced pancreatic β-cell function and enhanced hepatic gluconeogenesis, thereby resulting in hyperglycemia and glucose intolerance in casein-injected mice. Our results indicate a paradoxical effect of rapamycin on insulin resistance between the in vitro and in vivo environments under inflammatory stress and provide additional insight into the clinical application of rapamycin.
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Uno K, Yamada T, Ishigaki Y, Imai J, Hasegawa Y, Sawada S, Kaneko K, Ono H, Asano T, Oka Y, Katagiri H. A hepatic amino acid/mTOR/S6K-dependent signalling pathway modulates systemic lipid metabolism via neuronal signals. Nat Commun 2015; 6:7940. [PMID: 26268630 PMCID: PMC4557134 DOI: 10.1038/ncomms8940] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/30/2015] [Indexed: 12/15/2022] Open
Abstract
Metabolism is coordinated among tissues and organs via neuronal signals. Levels of circulating amino acids (AAs), which are elevated in obesity, activate the intracellular target of rapamycin complex-1 (mTORC1)/S6kinase (S6K) pathway in the liver. Here we demonstrate that hepatic AA/mTORC1/S6K signalling modulates systemic lipid metabolism via a mechanism involving neuronal inter-tissue communication. Hepatic expression of an AA transporter, SNAT2, activates the mTORC1/S6K pathway, and markedly elevates serum triglycerides (TGs), while downregulating adipose lipoprotein lipase (LPL). Hepatic Rheb or active-S6K expression have similar metabolic effects, whereas hepatic expression of dominant-negative-S6K inhibits TG elevation in SNAT2 mice. Denervation, pharmacological deafferentation and β-blocker administration suppress obesity-related hypertriglyceridemia with adipose LPL upregulation, suggesting that signals are transduced between liver and adipose tissue via a neuronal pathway consisting of afferent vagal and efferent sympathetic nerves. Thus, the neuronal mechanism uncovered here serves to coordinate amino acid and lipid levels and contributes to the development of obesity-related hypertriglyceridemia.
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Affiliation(s)
- Kenji Uno
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Tetsuya Yamada
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Yasushi Ishigaki
- Division of Diabetes and Metabolism, Iwate Medical University, Morioka 020-8505, Japan
| | - Junta Imai
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Yutaka Hasegawa
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Shojiro Sawada
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Keizo Kaneko
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Hiraku Ono
- The Fourth Department of Internal Medicine, Saitama Medical University, Saitama 350-0495, Japan
| | - Tomoichiro Asano
- Department of Medical Science, Graduate School of Medicine, University of Hiroshima, Hiroshima 734-8553, Japan
| | - Yoshitomo Oka
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Hideki Katagiri
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.,Japan Science and Technology Agency, CREST, Sendai 980-8575, Japan
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Ribosomal S6K1 in POMC and AgRP Neurons Regulates Glucose Homeostasis but Not Feeding Behavior in Mice. Cell Rep 2015; 11:335-43. [PMID: 25865886 PMCID: PMC4410943 DOI: 10.1016/j.celrep.2015.03.029] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/11/2015] [Accepted: 03/11/2015] [Indexed: 11/23/2022] Open
Abstract
Hypothalamic ribosomal S6K1 has been suggested as a point of convergence for hormonal and nutrient signals in the regulation of feeding behavior, bodyweight, and glucose metabolism. However, the long-term effects of manipulating hypothalamic S6K1 signaling on energy homeostasis and the cellular mechanisms underlying these roles are unclear. We therefore inactivated S6K1 in pro-opiomelanocortin (POMC) and agouti-related protein (AgRP) neurons, key regulators of energy homeostasis, but in contrast to the current view, we found no evidence that S6K1 regulates food intake and bodyweight. In contrast, S6K1 signaling in POMC neurons regulated hepatic glucose production and peripheral lipid metabolism and modulated neuronal excitability. S6K1 signaling in AgRP neurons regulated skeletal muscle insulin sensitivity and was required for glucose sensing by these neurons. Our findings suggest that S6K1 signaling is not a general integrator of energy homeostasis in the mediobasal hypothalamus but has distinct roles in the regulation of glucose homeostasis by POMC and AgRP neurons.
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Côté CD, Rasmussen BA, Duca FA, Zadeh-Tahmasebi M, Baur JA, Daljeet M, Breen DM, Filippi BM, Lam TKT. Resveratrol activates duodenal Sirt1 to reverse insulin resistance in rats through a neuronal network. Nat Med 2015; 21:498-505. [PMID: 25849131 DOI: 10.1038/nm.3821] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 02/06/2015] [Indexed: 12/12/2022]
Abstract
Resveratrol improves insulin sensitivity and lowers hepatic glucose production (HGP) in rat models of obesity and diabetes, but the underlying mechanisms for these antidiabetic effects remain elusive. One process that is considered a key feature of resveratrol action is the activation of the nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase sirtuin 1 (SIRT1) in various tissues. However, the low bioavailability of resveratrol raises questions about whether the antidiabetic effects of oral resveratrol can act directly on these tissues. We show here that acute intraduodenal infusion of resveratrol reversed a 3 d high fat diet (HFD)-induced reduction in duodenal-mucosal Sirt1 protein levels while also enhancing insulin sensitivity and lowering HGP. Further, we found that duodenum-specific knockdown of Sirt1 expression for 14 d was sufficient to induce hepatic insulin resistance in rats fed normal chow. We also found that the glucoregulatory role of duodenally acting resveratrol required activation of Sirt1 and AMP-activated protein kinase (Ampk) in this tissue to initiate a gut-brain-liver neuronal axis that improved hypothalamic insulin sensitivity and in turn, reduced HGP. In addition to the effects of duodenally acting resveratrol in an acute 3 d HFD-fed model of insulin resistance, we also found that short-term infusion of resveratrol into the duodenum lowered HGP in two other rat models of insulin resistance--a 28 d HFD-induced model of obesity and a nicotinamide (NA)-streptozotocin (STZ)-HFD-induced model of mild type 2 diabetes. Together, these studies highlight the therapeutic relevance of targeting duodenal SIRT1 to reverse insulin resistance and improve glucose homeostasis in obesity and diabetes.
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Affiliation(s)
- Clémence D Côté
- 1] Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada. [2] Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Brittany A Rasmussen
- 1] Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada. [2] Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Frank A Duca
- Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada
| | - Melika Zadeh-Tahmasebi
- 1] Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada. [2] Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Joseph A Baur
- Department of Physiology, Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mira Daljeet
- Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada
| | - Danna M Breen
- Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada
| | - Beatrice M Filippi
- Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada
| | - Tony K T Lam
- 1] Toronto General Research Institute and Department of Medicine, University Health Network, Toronto, Ontario, Canada. [2] Department of Physiology, University of Toronto, Toronto, Ontario, Canada. [3] Department of Medicine, University of Toronto, Toronto, Ontario, Canada. [4] Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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40
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Salmon AB, Lerner C, Ikeno Y, Motch Perrine SM, McCarter R, Sell C. Altered metabolism and resistance to obesity in long-lived mice producing reduced levels of IGF-I. Am J Physiol Endocrinol Metab 2015; 308:E545-53. [PMID: 25648834 PMCID: PMC4385875 DOI: 10.1152/ajpendo.00558.2014] [Citation(s) in RCA: 12] [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: 12/03/2014] [Accepted: 01/28/2015] [Indexed: 01/20/2023]
Abstract
The extension of lifespan due to reduced insulin-like growth factor 1 (IGF-I) signaling in mice has been proposed to be mediated through alterations in metabolism. Previously, we showed that mice homozygous for an insertion in the Igf1 allele have reduced levels of IGF-I, are smaller, and have an extension of maximum lifespan. Here, we tested whether this specific reduction of IGF-I alters glucose metabolism both on normal rodent chow and in response to high-fat feeding. We found that female IGF-I-deficient mice were lean on a standard rodent diet but paradoxically displayed an insulin-resistant phenotype. However, these mice gained significantly less weight than normal controls when placed on a high-fat diet. In control animals, insulin response was significantly impaired by high-fat feeding, whereas IGF-I-deficient mice showed a much smaller shift in insulin response after high-fat feeding. Gluconeogenesis was also elevated in the IGF-I-deficient mice relative to controls on both normal and high-fat diet. An analysis of metabolism and respiratory quotient over 24 h indicated that the IGF-I-deficient mice preferentially utilized fatty acids as an energy source when placed on a high-fat diet. These results indicate that reduction in the circulating and tissue IGF-I levels can produce a metabolic phenotype in female mice that increases peripheral insulin resistance but renders animals resistant to the deleterious effects of high-fat feeding.
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Affiliation(s)
- Adam B Salmon
- The Sam and Ann Barshop Institute for Longevity and Aging Studies, Department of Molecular Medicine, and The Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, Audie L. Murphy Veterans Affairs Hospital, San Antonio, Texas;
| | - Chad Lerner
- Department of Pathology and Laboratory Medicine, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Yuji Ikeno
- The Sam and Ann Barshop Institute for Longevity and Aging Studies, Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas; The Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, Audie L. Murphy Veterans Affairs Hospital, San Antonio, Texas
| | - Susan M Motch Perrine
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania; and
| | - Roger McCarter
- Center for Developmental and Health Genetics, Pennsylvania State University, University Park, Pennsylvania
| | - Christian Sell
- Department of Pathology and Laboratory Medicine, Drexel University College of Medicine, Philadelphia, Pennsylvania
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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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Abstract
The increase in the number of patients with diabetes has become a worldwide healthcare issue, with numbers predicted to reach approximately 600 million by 2035. In Asia-Pacific region, the prevalence of type 2 diabetes has increased dramatically in recent decades, of which the major causes are believed to be modern lifestyle changes, e.g., Western dietary pattern and reduced physical activity, on their genetic basis of lower insulin secretory capacity. Particularly, in East Asian countries, the amount of fat intake has increased nearly three-fold over this half of century; dietary fat appears to be the major culprit of type 2 diabetes pandemic in East Asia. However, convincing evidence has not yet been provided as to whether high-fat diet causes type 2 diabetes in epidemiological cohort studies. Here, we summarize clinical studies regarding fat intake and type 2 diabetes, and animal studies on high-fat diet-induced diabetes including our recent works on the novel mouse lines (selectively bred diet-induced glucose intolerance-prone [SDG-P] and -resistant [SDG-R]) to address the etiology of high-fat diet-induced diabetes. These epidemiological and experimental findings would provide further insight into the etiology of type 2 diabetes under the modern nutritional environment, namely in the context of increased fat intake.
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Affiliation(s)
- Mototsugu Nagao
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo 113-8603 Japan
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43
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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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Shin AC, Fasshauer M, Filatova N, Grundell LA, Zielinski E, Zhou JY, Scherer T, Lindtner C, White PJ, Lapworth AL, Ilkayeva O, Knippschild U, Wolf AM, Scheja L, Grove KL, Smith RD, Qian WJ, Lynch CJ, Newgard CB, Buettner C. Brain insulin lowers circulating BCAA levels by inducing hepatic BCAA catabolism. Cell Metab 2014; 20:898-909. [PMID: 25307860 PMCID: PMC4254305 DOI: 10.1016/j.cmet.2014.09.003] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 07/06/2014] [Accepted: 09/05/2014] [Indexed: 12/31/2022]
Abstract
Circulating branched-chain amino acid (BCAA) levels are elevated in obesity/diabetes and are a sensitive predictor for type 2 diabetes. Here we show in rats that insulin dose-dependently lowers plasma BCAA levels through induction of hepatic protein expression and activity of branched-chain α-keto acid dehydrogenase (BCKDH), the rate-limiting enzyme in the BCAA degradation pathway. Selective induction of hypothalamic insulin signaling in rats and genetic modulation of brain insulin receptors in mice demonstrate that brain insulin signaling is a major regulator of BCAA metabolism by inducing hepatic BCKDH. Short-term overfeeding impairs the ability of brain insulin to lower BCAAs in rats. High-fat feeding in nonhuman primates and obesity and/or diabetes in humans is associated with reduced BCKDH protein in liver. These findings support the concept that decreased hepatic BCKDH is a major cause of increased plasma BCAAs and that hypothalamic insulin resistance may account for impaired BCAA metabolism in obesity and diabetes.
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Affiliation(s)
- Andrew C Shin
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Martin Fasshauer
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Nika Filatova
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Linus A Grundell
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Elizabeth Zielinski
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jian-Ying Zhou
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352, USA
| | - Thomas Scherer
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Claudia Lindtner
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Phillip J White
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, 300 North Duke Street, Durham, NC 27710, USA
| | - Amanda L Lapworth
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, 300 North Duke Street, Durham, NC 27710, USA
| | - Olga Ilkayeva
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, 300 North Duke Street, Durham, NC 27710, USA
| | - Uwe Knippschild
- Department of General and Visceral Surgery, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Anna M Wolf
- Department of General and Visceral Surgery, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Ludger Scheja
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Kevin L Grove
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR 97006, USA
| | - Richard D Smith
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352, USA
| | - Wei-Jun Qian
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352, USA
| | - Christopher J Lynch
- Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Christopher B Newgard
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, 300 North Duke Street, Durham, NC 27710, USA
| | - Christoph Buettner
- Diabetes, Obesity, and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA.
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Xiao F, Xia T, Lv Z, Zhang Q, Xiao Y, Yu J, Liu H, Deng J, Guo Y, Wang C, Li K, Liu B, Chen S, Guo F. Central prolactin receptors (PRLRs) regulate hepatic insulin sensitivity in mice via signal transducer and activator of transcription 5 (STAT5) and the vagus nerve. Diabetologia 2014; 57:2136-44. [PMID: 25064125 DOI: 10.1007/s00125-014-3336-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/24/2014] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS Recent studies have revealed the crucial role of the central nervous system (CNS), especially the hypothalamus, in the regulation of insulin sensitivity in peripheral tissues. The aim of our current study was to investigate the possible involvement of hypothalamic prolactin receptors (PRLRs) in the regulation of hepatic insulin sensitivity. METHODS We employed overexpression of PRLRs in mouse hypothalamus via intracerebroventricular injection of adenovirus expressing PRLR and inhibition of PRLRs via adenovirus expressing short-hairpin RNA (shRNA) specific for PRLRs in vivo. Selective hepatic vagotomy was employed to verify the important role of the vagus nerve in mediating signals from the brain to peripheral organs. In addition, a genetic insulin-resistant animal model, the db/db mouse, was used in our study to investigate the role of hypothalamic PRLRs in regulating whole-body insulin sensitivity. RESULTS Overexpression of PRLRs in the hypothalamus improved hepatic insulin sensitivity in mice and inhibition of hypothalamic PRLRs had the opposite effect. In addition, we demonstrated that hypothalamic PRLR-improved insulin sensitivity was significantly attenuated by inhibiting the activity of signal transducer and activator of transcription 5 (STAT5) in the CNS and by selective hepatic vagotomy. Finally, overexpression of PRLRs significantly ameliorated insulin resistance in db/db mice. CONCLUSIONS/INTERPRETATION Our study identifies a novel central pathway involved in the regulation of hepatic insulin sensitivity, mediated by hypothalamic PRLR/STAT5 signalling and the vagus nerve, thus demonstrating an important role for hypothalamic PRLRs under conditions of insulin resistance.
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Affiliation(s)
- Fei Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, People's Republic of China
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Yu IC, Lin HY, Sparks JD, Yeh S, Chang C. Androgen receptor roles in insulin resistance and obesity in males: the linkage of androgen-deprivation therapy to metabolic syndrome. Diabetes 2014; 63:3180-8. [PMID: 25249645 PMCID: PMC4171661 DOI: 10.2337/db13-1505] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Prostate cancer (PCa) is one of the most frequently diagnosed malignancies in men. Androgen-deprivation therapy (ADT) is the first-line treatment and fundamental management for men with advanced PCa to suppress functions of androgen/androgen receptor (AR) signaling. ADT is effective at improving cancer symptoms and prolonging survival. However, epidemiological and clinical studies support the notion that testosterone deficiency in men leads to the development of metabolic syndrome that increases cardiovascular disease risk. The underlying mechanisms by which androgen/AR signaling regulates metabolic homeostasis in men are complex, and in this review, we discuss molecular mechanisms mediated by AR signaling that link ADT to metabolic syndrome. Results derived from various AR knockout mouse models reveal tissue-specific AR signaling that is involved in regulation of metabolism. These data suggest that steps be taken early to manage metabolic complications associated with PCa patients receiving ADT, which could be accomplished using tissue-selective modulation of AR signaling and by treatment with insulin-sensitizing agents.
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Affiliation(s)
- I-Chen Yu
- Department of Pathology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Department of Urology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY
| | - Hung-Yun Lin
- Department of Pathology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Department of Urology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY
| | - Janet D Sparks
- Department of Pathology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Department of Urology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY
| | - Shuyuan Yeh
- Department of Pathology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Department of Urology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY
| | - Chawnshang Chang
- Department of Pathology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Department of Urology, George Whipple Laboratory for Cancer Research, University of Rochester Medical Center, Rochester, NY Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY Sex Hormone Research Center, China Medical University/Hospital, Taichung, Taiwan
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Takei N, Furukawa K, Hanyu O, Sone H, Nawa H. A possible link between BDNF and mTOR in control of food intake. Front Psychol 2014; 5:1093. [PMID: 25309497 PMCID: PMC4174734 DOI: 10.3389/fpsyg.2014.01093] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/09/2014] [Indexed: 12/30/2022] Open
Abstract
Food intake is intricately regulated by glucose, amino acids, hormones, neuropeptides, and trophic factors through a neural circuit in the hypothalamus. Brain-derived neurotrophic factor (BDNF), the most prominent neurotrophic factor in the brain, regulates differentiation, maturation, and synaptic plasticity throughout life. Among its many roles, BDNF exerts an anorexigenic function in the brain. However, the intracellular signaling induced by BDNF to control food intake is not fully understood. One candidate for the molecule involved in transducing the anorexigenic activity of BDNF is the mammalian target of rapamycin (mTOR). mTOR senses extracellular amino acids, glucose, growth factors, and neurotransmitters, and regulates anabolic reactions response to these signals. Activated mTOR increases protein and lipid synthesis and inhibits protein degradation. In the hypothalamus, mTOR activation is thought to reduce food intake. Here we summarize recent findings regarding BDNF- and mTOR-mediated feeding control, and propose a link between these molecules in eating behavior.
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Affiliation(s)
- Nobuyuki Takei
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata Japan
| | - Kazuo Furukawa
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata Japan ; Department of Hematology, Endocrinology and Metabolism, Faculty of Medicine, Niigata University, Niigata Japan
| | - Osamu Hanyu
- Department of Hematology, Endocrinology and Metabolism, Faculty of Medicine, Niigata University, Niigata Japan
| | - Hirohito Sone
- Department of Hematology, Endocrinology and Metabolism, Faculty of Medicine, Niigata University, Niigata Japan
| | - Hiroyuki Nawa
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata Japan
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Short-term high-fat-and-fructose feeding produces insulin signaling alterations accompanied by neurite and synaptic reduction and astroglial activation in the rat hippocampus. J Cereb Blood Flow Metab 2014; 34:1001-8. [PMID: 24667917 PMCID: PMC4050245 DOI: 10.1038/jcbfm.2014.48] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 02/20/2014] [Accepted: 02/24/2014] [Indexed: 11/09/2022]
Abstract
Chronic consumption of high-fat-and-fructose diets (HFFD) is associated with the development of insulin resistance (InsRes) and obesity. Systemic insulin resistance resulting from long-term HFFD feeding has detrimental consequences on cognitive performance, neurogenesis, and long-term potentiation establishment, accompanied by neuronal alterations in the hippocampus. However, diet-induced hippocampal InsRes has not been reported. Therefore, we investigated whether short-term HFFD feeding produced hippocampal insulin signaling alterations associated with neuronal changes in the hippocampus. Rats were fed with a control diet or an HFFD consisting of 10% lard supplemented chow and 20% high-fructose syrup in the drinking water. Our results show that 7 days of HFFD feeding induce obesity and InsRes, associated with the following alterations in the hippocampus: (1) a decreased insulin signaling; (2) a decreased hippocampal weight; (3) a reduction in dendritic arborization in CA1 and microtubule-associated protein 2 (MAP-2) levels; (4) a decreased dendritic spine number in CA1 and synaptophysin content, along with an increase in tau phosphorylation; and finally, (5) an increase in reactive astrocyte associated with microglial changes. To our knowledge, this is the first report addressing hippocampal insulin signaling, as well as morphologic, structural, and functional modifications due to short-term HFFD feeding in the rat.
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Knobler H, Elson A. Metabolic regulation by protein tyrosine phosphatases. J Biomed Res 2014; 28:157-68. [PMID: 25013399 PMCID: PMC4085553 DOI: 10.7555/jbr.28.20140012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 01/28/2014] [Indexed: 01/14/2023] Open
Abstract
Obesity and the metabolic syndrome and their associated morbidities are major public health issues, whose prevalence will continue to increase in the foreseeable future. Aberrant signaling by the receptors for leptin and insulin plays a pivotal role in development of the metabolic syndrome. More complete molecular-level understanding of how both of these key signaling pathways are regulated is essential for full characterization of obesity, the metabolic syndrome, and type II diabetes, and for developing novel treatments for these diseases. Phosphorylation of proteins on tyrosine residues plays a key role in mediating the effects of leptin and insulin on their target cells. Here, we discuss the molecular methods by which protein tyrosine phosphatases, which are key physiological regulators of protein phosphorylation in vivo, affect signaling by the leptin and insulin receptors in their major target tissues.
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Affiliation(s)
- Hilla Knobler
- Diabetes and Metabolic Disease Unit, Kaplan Medical Center, Rehovot 76100, Israel
| | - Ari Elson
- Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot 76100, Israel
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Lutaif NA, Palazzo R, Gontijo JAR. Early detection of metabolic and energy disorders by thermal time series stochastic complexity analysis. Braz J Med Biol Res 2014; 47:70-9. [PMID: 24519093 PMCID: PMC3932975 DOI: 10.1590/1414-431x20133097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 08/06/2013] [Indexed: 11/22/2022] Open
Abstract
Maintenance of thermal homeostasis in rats fed a high-fat diet (HFD) is
associated with changes in their thermal balance. The thermodynamic relationship
between heat dissipation and energy storage is altered by the ingestion of
high-energy diet content. Observation of thermal registers of core temperature
behavior, in humans and rodents, permits identification of some characteristics
of time series, such as autoreference and stationarity that fit adequately to a
stochastic analysis. To identify this change, we used, for the first time, a
stochastic autoregressive model, the concepts of which match those associated
with physiological systems involved and applied in male HFD rats compared with
their appropriate standard food intake age-matched male controls (n=7 per
group). By analyzing a recorded temperature time series, we were able to
identify when thermal homeostasis would be affected by a new diet. The
autoregressive time series model (AR model) was used to predict the occurrence
of thermal homeostasis, and this model proved to be very effective in
distinguishing such a physiological disorder. Thus, we infer from the results of
our study that maximum entropy distribution as a means for stochastic
characterization of temperature time series registers may be established as an
important and early tool to aid in the diagnosis and prevention of metabolic
diseases due to their ability to detect small variations in thermal profile.
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Affiliation(s)
- N A Lutaif
- Universidade Estadual de Campinas, Faculdade de Ciências Médicas, Departamento de Clínica Médica, CampinasSP, Brasil
| | - R Palazzo
- Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e Computação, Departamento de Telemática, CampinasSP, Brasil
| | - J A R Gontijo
- Universidade Estadual de Campinas, Faculdade de Ciências Médicas, Departamento de Clínica Médica, CampinasSP, Brasil
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