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De la Cruz-Color L, Dominguez-Rosales JA, Maldonado-González M, Ruíz-Madrigal B, Sánchez Muñoz MP, Zaragoza-Guerra VA, Espinoza-Padilla VH, Ruelas-Cinco EDC, Ramírez-Meza SM, Torres Baranda JR, González-Gutiérrez MDR, Hernandez Nazara ZH. Evidence That Peripheral Leptin Resistance in Omental Adipose Tissue and Liver Correlates with MASLD in Humans. Int J Mol Sci 2024; 25:6420. [PMID: 38928125 PMCID: PMC11203746 DOI: 10.3390/ijms25126420] [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: 05/07/2024] [Revised: 06/04/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
Leptin regulates lipid metabolism, maximizing insulin sensitivity; however, peripheral leptin resistance is not fully understood, and its contribution to metabolic dysfunction-associated steatotic liver disease (MASLD) is unclear. This study evaluated the contribution of the leptin axis to MASLD in humans. Forty-three participants, mostly female (86.04%), who underwent cholecystectomy were biopsied. Of the participants, 24 were healthy controls, 8 had MASLD, and 11 had metabolic dysfunction-associated steatohepatitis (MASH). Clinical and biochemical data and the gene expression of leptin, leptin receptor (LEPR), suppressor of cytokine signaling 3 (SOCS3), sterol regulatory element-binding transcription factor 1 (SREBF1), stearoyl-CoA desaturase-1 (SCD1), and patatin-like phospholipase domain-containing protein 2 (PNPLA2), were determined from liver and adipose tissue. Higher serum leptin and LEPR levels in the omental adipose tissue (OAT) and liver with MASH were found. In the liver, LEPR was positively correlated with leptin expression in adipose tissue, and SOCS3 was correlated with SREBF1-SCD1. In OAT, SOCS3 was correlated with insulin resistance and transaminase enzymes (p < 0.05 for all. In conclusion, we evidenced the correlation between the peripheral leptin resistance axis in OAT-liver crosstalk and the complications of MASLD in humans.
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Affiliation(s)
- Lucia De la Cruz-Color
- Centro de Investigación en Biotecnología Microbiana y Alimentaria, División de Desarrollo Biotecnológico, Centro Universitario de la Ciénega, Universidad de Guadalajara, Ocotlán 47820, C.P., Mexico;
- Instituto de Investigación en Enfermedades Crónicas Degenerativas, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico (V.H.E.-P.)
| | - Jose Alfredo Dominguez-Rosales
- Instituto de Investigación en Enfermedades Crónicas Degenerativas, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico (V.H.E.-P.)
| | - Montserrat Maldonado-González
- Laboratorio de Investigación en Microbiología, Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico; (M.M.-G.); (B.R.-M.); (J.R.T.B.)
| | - Bertha Ruíz-Madrigal
- Laboratorio de Investigación en Microbiología, Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico; (M.M.-G.); (B.R.-M.); (J.R.T.B.)
| | - Martha P. Sánchez Muñoz
- Nuevo Hospital Civil de Guadalajara Dr. Juan I. Menchaca, Unidad de Cirugía Bariátrica y Metabólica, Guadalajara 44340, C.P., Mexico;
| | - Vianney Alejandrina Zaragoza-Guerra
- Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Guadalajara, Escuela de Medicina y Ciencias de la Salud, Zapopan 45201, C.P., Mexico; (V.A.Z.-G.); (M.d.R.G.-G.)
| | - Victor H. Espinoza-Padilla
- Instituto de Investigación en Enfermedades Crónicas Degenerativas, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico (V.H.E.-P.)
| | | | - Sandra M. Ramírez-Meza
- Coordinación de la Licenciatura en Nutrición, División de Estudios de la Salud Centro Universitario de los Valles, Universidad de Guadalajara, Ameca Km. 45.5, Ameca 46600, C.P., Mexico;
| | - José R. Torres Baranda
- Laboratorio de Investigación en Microbiología, Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico; (M.M.-G.); (B.R.-M.); (J.R.T.B.)
| | - María del R. González-Gutiérrez
- Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Guadalajara, Escuela de Medicina y Ciencias de la Salud, Zapopan 45201, C.P., Mexico; (V.A.Z.-G.); (M.d.R.G.-G.)
| | - Zamira Helena Hernandez Nazara
- Instituto de Investigación en Enfermedades Crónicas Degenerativas, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, C.P., Mexico (V.H.E.-P.)
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The central nervous system control of energy homeostasis: high fat diet induced hypothalamic microinflammation and obesity. Brain Res Bull 2022; 185:99-106. [PMID: 35525336 DOI: 10.1016/j.brainresbull.2022.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 04/27/2022] [Accepted: 04/30/2022] [Indexed: 11/22/2022]
Abstract
Obesity is believed to arise through the imbalance of energy homeostasis controlled by the central nervous system, where the hypothalamus plays the fundamental role in energy metabolism. In this review, we will provide an overview regarding the functions of POMC neurons and AgRP neurons in acute nucleus of the hypothalamus which mediated the energy metabolism, highlighting their interactions with peripheral organs derived hormones in control of energy homeostasis. Furthermore, the role of high fat diet induced hypothalamic microinflammation in the pathogenesis of obesity will be discussed. We hope this review could help researchers to understand the mechanism of hypothalamus in control of energy metabolism, and design related drugs to block the pathways involving in the impaired metabolism in obese patients.
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Su H, Liu N, Zhang Y, Kong J. Vitamin D/VDR regulates peripheral energy homeostasis via central renin-angiotensin system. J Adv Res 2021; 33:69-80. [PMID: 34603779 PMCID: PMC8463910 DOI: 10.1016/j.jare.2021.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 01/19/2023] Open
Abstract
Introduction Some epidemiological studies have revealed that vitamin D (VD) deficiency is closely linked with the prevalence of obesity, however, the role of VD in energy homeostasis is yet to be investigated, especially in central nervous system. Given that VD negatively regulates renin in adipose tissue, we hypothesized that central VD might play a potential role in energy homeostasis. Objectives The present study aims to investigate the potential role of VD in energy homeostasis in the CNS and elaborate its underlying mechanisms. Methods This study was conducted in Cyp27b1−/− mice, VD-treated and wild-type mice. After the intraventricular injection of renin or its inhibitors, the changes of renin-angiotensin system (RAS) and its down-stream pathway as well as their effects on metabolic rate were examined. Results The RAS activity was enhanced in Cyp27b1−/− mice, exhibiting a increased metabolic rate. Additionally, corticotropin-releasing hormone (CRH), a RAS-mediated protein regulating energy metabolism in the hypothalamus, increased significantly in Cyp27b1−/− mice. While in VD-treated group, the RAS and sympathetic nerve activities were slightly inhibited, hence the reduced metabolic rate. Conclusion Collectively, the present study demonstrates that the VD/vitamin D receptor (VDR) has a significant impact on energy homeostasis through the modulation of RAS activity in the hypothalamus, subsequently altering CRH expression and sympathetic nervous activity.
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Affiliation(s)
- Han Su
- Department of Clinical Nutrition, Shengjing Hospital of China Medical University, Shenyang, China
| | - Ning Liu
- Department of Clinical Nutrition, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yalin Zhang
- Department of Clinical Nutrition, Shengjing Hospital of China Medical University, Shenyang, China
| | - Juan Kong
- Department of Clinical Nutrition, Shengjing Hospital of China Medical University, Shenyang, China
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Leptin-Activity Modulators and Their Potential Pharmaceutical Applications. Biomolecules 2021; 11:biom11071045. [PMID: 34356668 PMCID: PMC8301849 DOI: 10.3390/biom11071045] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/08/2021] [Accepted: 07/13/2021] [Indexed: 12/12/2022] Open
Abstract
Leptin, a multifunctional hormone primarily, but not exclusively, secreted in adipose tissue, is implicated in a wide range of biological functions that control different processes, such as the regulation of body weight and energy expenditure, reproductive function, immune response, and bone metabolism. In addition, leptin can exert angiogenic and mitogenic actions in peripheral organs. Leptin biological activities are greatly related to its interaction with the leptin receptor. Both leptin excess and leptin deficiency, as well as leptin resistance, are correlated with different human pathologies, such as autoimmune diseases and cancers, making leptin and leptin receptor important drug targets. The development of leptin signaling modulators represents a promising strategy for the treatment of cancers and other leptin-related diseases. In the present manuscript, we provide an update review about leptin-activity modulators, comprising leptin mutants, peptide-based leptin modulators, as well as leptin and leptin receptor specific monoclonal antibodies and nanobodies.
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Liu H, Du T, Li C, Yang G. STAT3 phosphorylation in central leptin resistance. Nutr Metab (Lond) 2021; 18:39. [PMID: 33849593 PMCID: PMC8045279 DOI: 10.1186/s12986-021-00569-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/03/2021] [Indexed: 12/20/2022] Open
Abstract
Mechanism exploitation of energy homeostasis is urgently required because of the worldwide prevailing of obesity-related metabolic disorders in human being. Although it is well known that leptin plays a central role in regulating energy balance by suppressing food intake and promoting energy expenditure, the existence of leptin resistance in majority of obese individuals hampers the utilization of leptin therapy against these disorders. However, the mechanism of leptin resistance is largely unknown in spite of the globally enormous endeavors. Current theories to interpret leptin resistance include the impairment of leptin transport, attenuation of leptin signaling, chronic inflammation, ER tress, deficiency of autophagy, as well as leptin itself. Leptin-activated leptin receptor (LepRb) signals in hypothalamus via several pathways, in which JAK2-STAT3 pathway, the most extensively investigated one, is considered to mediate the major action of leptin in energy regulation. Upon leptin stimulation the phosphorylation of STAT3 is one of the key events in JAK2-STAT3 pathway, followed by the dimerization and nuclear translocation of this molecule. Phosphorylated STAT3 (p-STAT3), as a transcription factor, binds to and regulates its target gene such as POMC gene, playing the physiological function of leptin. Regarding POMC gene in hypothalamus however little is known about the detail of its interaction with STAT3. Moreover the status of p-STAT3 and its significance in hypothalamus of DIO mice needs to be well elucidated. This review comprehends literatures on leptin and leptin resistance and especially discusses what STAT3 phosphorylation would contribute to central leptin resistance.
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Affiliation(s)
- Huimin Liu
- College of Life Science, Henan Agricultural University, 95 Wen Hua Road, Zhengzhou, 450002, China
| | - Tianxin Du
- College of Life Science, Henan Agricultural University, 95 Wen Hua Road, Zhengzhou, 450002, China
| | - Chen Li
- College of Life Science, Henan Agricultural University, 95 Wen Hua Road, Zhengzhou, 450002, China
| | - Guoqing Yang
- College of Life Science, Henan Agricultural University, 95 Wen Hua Road, Zhengzhou, 450002, China.
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Inamori KI, Ito H, Tamura Y, Nitta T, Yang X, Nihei W, Shishido F, Imazu S, Tsukita S, Yamada T, Katagiri H, Inokuchi JI. Deficient ganglioside synthesis restores responsiveness to leptin and melanocortin signaling in obese KKAy mice. J Lipid Res 2018; 59:1472-1481. [PMID: 29880531 DOI: 10.1194/jlr.m085753] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/22/2018] [Indexed: 11/20/2022] Open
Abstract
GM3, a precursor for synthesis of a- and b-series gangliosides, is elevated in adipocytes of obese model animals and in sera of obese human patients with type 2 diabetes and/or dyslipidemia. GM3 synthase (GM3S)-KO C57BL/6 mice display enhanced insulin sensitivity and reduced development of high-fat diet-induced insulin resistance. However, the pathophysiological roles of GM3 and related gangliosides in the central control of feeding and metabolism remain unclear. We found that a mouse model (KKAy GM3S KO) generated by KO of the GM3S gene in the yellow obese strain, KKAy, displayed significant amelioration of obese phenotype. Whereas KKAy mice were hyperphagic and developed severe obesity, KKAy GM3S KO mice had significantly lower body weight and food intake, and greater glucose and insulin tolerance. The hypothalamic response to intraperitoneal administration of leptin was greatly reduced in KKAy mice, but was retained in KKAy GM3S KO mice. In studies of a cultured mouse hypothalamic neuronal cell line, enhanced leptin-dependent phosphorylation of ERK was observed in GM3S-deficient cells. Furthermore, KKAy GM3S KO mice did show altered coat color, suggesting that GM3S is also involved in melanocortin signaling. Our findings, taken together, indicate that GM3-related gangliosides play key roles in leptin and melanocortin signaling.
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Affiliation(s)
- Kei-Ichiro Inamori
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Hideki Ito
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Yumi Tamura
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Takahiro Nitta
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Xiaohua Yang
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Wataru Nihei
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Fumi Shishido
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Susumu Imazu
- Nippon Boehringer Ingelheim Company, Ltd., Shinagawa-Ku, Tokyo 141-6017, Japan
| | - Sohei Tsukita
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan
| | - Tetsuya Yamada
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan
| | - Hideki Katagiri
- Department of Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan
| | - Jin-Ichi Inokuchi
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
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Inokuchi JI, Inamori KI, Kabayama K, Nagafuku M, Uemura S, Go S, Suzuki A, Ohno I, Kanoh H, Shishido F. Biology of GM3 Ganglioside. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 156:151-195. [PMID: 29747813 DOI: 10.1016/bs.pmbts.2017.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Since the successful molecular cloning in 1998 of GM3 synthase (GM3S, ST3GAL5), the enzyme responsible for initiating biosynthesis of all complex gangliosides, the efforts of our research group have been focused on clarifying the physiological and pathological implications of gangliosides, particularly GM3. We have identified isoforms of GM3S proteins having distinctive lengths of N-terminal cytoplasmic tails, and found that these cytoplasmic tails define subcellular localization, stability, and in vivo activity of GM3S isoforms. Our studies of the molecular pathogenesis of type 2 diabetes, focused on interaction between insulin receptor and GM3 in membrane microdomains, led to a novel concept: type 2 diabetes and certain other lifestyle-related diseases are membrane microdomain disorders resulting from aberrant expression of gangliosides. This concept has enhanced our understanding of the pathophysiological roles of GM3 and related gangliosides in various diseases involving chronic inflammation, such as insulin resistance, leptin resistance, and T-cell function and immune disorders (e.g., allergic asthma). We also demonstrated an essential role of GM3 in murine and human auditory systems; a common pathological feature of GM3S deficiency is deafness. This is the first direct link reported between gangliosides and auditory functions.
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Affiliation(s)
- Jin-Ichi Inokuchi
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan.
| | - Kei-Ichiro Inamori
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | | | - Masakazu Nagafuku
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Satoshi Uemura
- Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Shinji Go
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Akemi Suzuki
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Isao Ohno
- Center for Medical Education, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Hirotaka Kanoh
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Fumi Shishido
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
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Wauman J, Zabeau L, Tavernier J. The Leptin Receptor Complex: Heavier Than Expected? Front Endocrinol (Lausanne) 2017; 8:30. [PMID: 28270795 PMCID: PMC5318964 DOI: 10.3389/fendo.2017.00030] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/01/2017] [Indexed: 12/31/2022] Open
Abstract
Under normal physiological conditions, leptin and the leptin receptor (ObR) regulate the body weight by balancing food intake and energy expenditure. However, this adipocyte-derived hormone also directs peripheral processes, including immunity, reproduction, and bone metabolism. Leptin, therefore, can act as a metabolic switch connecting the body's nutritional status to high energy consuming processes. We provide an extensive overview of current structural insights on the leptin-ObR interface and ObR activation, coupling to signaling pathways and their negative regulation, and leptin functioning under normal and pathophysiological conditions (obesity, autoimmunity, cancer, … ). We also discuss possible cross-talk with other receptor systems on the receptor (extracellular) and signaling cascade (intracellular) levels.
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Affiliation(s)
- Joris Wauman
- Cytokine Receptor Laboratory, Faculty of Medicine and Health Sciences, Department of Biochemistry, Ghent University, Ghent, Belgium
- VIB Medical Biotechnology Center, VIB, Ghent, Belgium
| | - Lennart Zabeau
- Cytokine Receptor Laboratory, Faculty of Medicine and Health Sciences, Department of Biochemistry, Ghent University, Ghent, Belgium
- VIB Medical Biotechnology Center, VIB, Ghent, Belgium
| | - Jan Tavernier
- Cytokine Receptor Laboratory, Faculty of Medicine and Health Sciences, Department of Biochemistry, Ghent University, Ghent, Belgium
- VIB Medical Biotechnology Center, VIB, Ghent, Belgium
- *Correspondence: Jan Tavernier,
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Shpakov AO. The brain leptin signaling system and its functional state in metabolic syndrome and type 2 diabetes mellitus. J EVOL BIOCHEM PHYS+ 2016. [DOI: 10.1134/s0022093016030017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Tu X, Kuang Z, Gong X, Shi Y, Yu L, Shi H, Wang J, Sun Z. The Influence of LepR Tyrosine Site Mutations on Mouse Ovary Development and Related Gene Expression Changes. PLoS One 2015; 10:e0141800. [PMID: 26529315 PMCID: PMC4631549 DOI: 10.1371/journal.pone.0141800] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 10/13/2015] [Indexed: 11/30/2022] Open
Abstract
Leptin exerts many biological functions, such as in metabolism and reproduction, through binding to and activating the leptin receptor, LepRb, which is expressed in many regions of the brain. To better understand the roles of LepR downstream signaling pathways, Y123F mice, which expressed mutant leptin receptors with phenylalanine (F) substituted for three tyrosines (Y) (Tyr985, Tyr1077 and Tyr1138), were generated. The body weight and abdominal fat deposits of Y123F homozygous mice (HOM) were higher than those of wild-type mice (WT). HOM ovaries were atrophic and the follicles developed abnormally; however, the HOM ovaries did not exhibit polycystic phenotypes. Moreover, Y123F HOM adults had no estrous cycle and the blood estrogen concentration remained stable at a low level below detection limit of 5 pg/ml. LepR expression in HOM ovaries was higher than in WT ovaries. Using cDNA Microarrays, the mRNA expressions of 41 genes were increased, and 100 were decreased in HOM vs. WT ovaries, and many signaling pathways were evaluated to be involved significantly. The expressions of 19 genes were validated by real-time quantitative PCR, most of which were consistent with the microarray results. Thus, Y123F HOM mice were suggested as a new animal model of PCOS for research that mainly emphasizes metabolic disorders and anovulation, but not the polycystic phenotype. Meanwhile, using the model, we found that JAK-STAT and hormone biosynthesis pathways were involved in the follicular development and ovulation disorders caused by LepR deficiency in ovaries, although we could not exclude indirect actions from the brain.
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Affiliation(s)
- Xiaoyu Tu
- Shanghai Medical College, Institute of Reproduction and Development, Fudan University, Shanghai, P. R. China
| | - Zhichao Kuang
- Shanghai Medical College, Institute of Reproduction and Development, Fudan University, Shanghai, P. R. China
| | - Xia Gong
- Department of Food Science, Shanghai Business School, Shanghai, P. R. China
| | - Yan Shi
- Key Laboratory of Contraceptive Drugs and Devices of National Population and Family Planning Commission of China, Shanghai Institute of Planned Parenthood Research, Shanghai, P. R. China
| | - Lin Yu
- Key Laboratory of Contraceptive Drugs and Devices of National Population and Family Planning Commission of China, Shanghai Institute of Planned Parenthood Research, Shanghai, P. R. China
| | - Huijuan Shi
- Key Laboratory of Contraceptive Drugs and Devices of National Population and Family Planning Commission of China, Shanghai Institute of Planned Parenthood Research, Shanghai, P. R. China
| | - Jian Wang
- Key Laboratory of Contraceptive Drugs and Devices of National Population and Family Planning Commission of China, Shanghai Institute of Planned Parenthood Research, Shanghai, P. R. China
| | - Zhaogui Sun
- Key Laboratory of Contraceptive Drugs and Devices of National Population and Family Planning Commission of China, Shanghai Institute of Planned Parenthood Research, Shanghai, P. R. China
- * E-mail:
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Yin Y, Liu W, Dai Y. SOCS3 and its role in associated diseases. Hum Immunol 2015; 76:775-80. [DOI: 10.1016/j.humimm.2015.09.037] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/03/2015] [Accepted: 09/26/2015] [Indexed: 11/27/2022]
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12
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Guadalupe-Grau A, Larsen S, Guerra B, Calbet JAL, Dela F, Helge JW. Influence of age on leptin induced skeletal muscle signalling. Acta Physiol (Oxf) 2014; 211:214-28. [PMID: 24605926 DOI: 10.1111/apha.12273] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/03/2013] [Accepted: 03/04/2014] [Indexed: 12/27/2022]
Abstract
AIM Age associated fat mass accumulation could be because of dysregulation of leptin signalling in skeletal muscle. Thus, we investigated total protein expression and phosphorylation levels of the long isoform of the leptin receptor (OB-Rb), and leptin signalling through janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3), insulin receptor substrate 1 (IRS-1), AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC), combined with the leptin signalling inhibitors suppressor of cytokine signalling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) in human skeletal muscle of different age. METHODS Vastus lateralis muscle biopsies were obtained from 39 men matched for BMI < 30 kg m(-2) and separated into three groups: 13 young (Y, 24 ± 4 years); 14 middle aged (MA, 44 ± 5 years) and 12 aged (A, 58 ± 8 years) subjects. RESULTS Whole body fat percentage and plasma leptin were higher (P < 0.05), whereas lean mass, plasma free testosterone and total testosterone were lower (P < 0.05) in A compared to Y. Skeletal muscle OB-Rb (170 KDa) protein expression and pTyr(1141) -OB-R170 were comparable between groups, whereas pTyr(985) -OB-R170 was lower in A compared to Y (P < 0.05). pSTAT3 levels tended (P = 0.09) to be lower (50%) in A compared to Y. In A, muscle PTP1B was greater and IRS-1 lower than Y and MA respectively (P < 0.05). PTyr(612) -IRS-1 tended to be lower in A than in Y (P = 0.09). Suppressor of cytokine signalling 3 (SOCS3) protein expression, pJAK2, pSer(1101) -IRS-1, pAMPKα and pACCβ were similar between groups. CONCLUSION Age is associated with dysregulation of the leptin signalling and increased PTP1B protein expression in skeletal muscle.
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Affiliation(s)
- A. Guadalupe-Grau
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - S. Larsen
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - B. Guerra
- Department of Clinical Sciences; Molecular and Translational Endocrinology Group; Associate Unit of University of Las Palmas de Gran Canaria and Biomedical Institute “Alberto Sols” - CSIC; Las Palmas de Gran Canaria Spain
- ICIC; Cancer Research Institute of the Canary Islands; Las Palmas de Gran Canaria Spain
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias; Las Palmas de Gran Canaria Spain
| | - J. A. L. Calbet
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias; Las Palmas de Gran Canaria Spain
| | - F. Dela
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - J. W. Helge
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
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13
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Zhang Q, Liu B, Cheng Y, Meng Q, Xia T, Jiang L, Chen S, Liu Y, Guo F. Leptin signaling is required for leucine deprivation-enhanced energy expenditure. J Biol Chem 2013; 289:1779-87. [PMID: 24302741 DOI: 10.1074/jbc.m113.528943] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Leptin signaling in the hypothalamus is crucial in energy homeostasis. We have previously shown that dietary deprivation of the essential amino acid leucine in mice stimulates fat loss by increasing energy expenditure. The involvement of leptin signaling in this regulation, however, has not been reported. Here, we show that leucine deprivation promotes leptin signaling in mice maintained on an otherwise normal diet and restores leptin responses in mice maintained on a high fat diet, a regimen known to induce leptin resistance. In addition, we found that leucine deprivation stimulated energy expenditure, and fat loss was largely blocked in db/db mice homozygous for a mutation in leptin receptor and a knock-in mouse line Y3F with abrogation of leptin receptor Tyr(1138)-mediated signal transducer and activator transcript 3 signaling. Overall, our studies describe a novel link between hypothalamic leptin signaling and stimulation of energy expenditure under leucine deprivation.
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Affiliation(s)
- Qian Zhang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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14
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Moon HS, Dalamaga M, Kim SY, Polyzos SA, Hamnvik OP, Magkos F, Paruthi J, Mantzoros CS. Leptin's role in lipodystrophic and nonlipodystrophic insulin-resistant and diabetic individuals. Endocr Rev 2013; 34:377-412. [PMID: 23475416 PMCID: PMC3660716 DOI: 10.1210/er.2012-1053] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Leptin is an adipocyte-secreted hormone that has been proposed to regulate energy homeostasis as well as metabolic, reproductive, neuroendocrine, and immune functions. In the context of open-label uncontrolled studies, leptin administration has demonstrated insulin-sensitizing effects in patients with congenital lipodystrophy associated with relative leptin deficiency. Leptin administration has also been shown to decrease central fat mass and improve insulin sensitivity and fasting insulin and glucose levels in HIV-infected patients with highly active antiretroviral therapy (HAART)-induced lipodystrophy, insulin resistance, and leptin deficiency. On the contrary, the effects of leptin treatment in leptin-replete or hyperleptinemic obese individuals with glucose intolerance and diabetes mellitus have been minimal or null, presumably due to leptin tolerance or resistance that impairs leptin action. Similarly, experimental evidence suggests a null or a possibly adverse role of leptin treatment in nonlipodystrophic patients with nonalcoholic fatty liver disease. In this review, we present a description of leptin biology and signaling; we summarize leptin's contribution to glucose metabolism in animals and humans in vitro, ex vivo, and in vivo; and we provide insights into the emerging clinical applications and therapeutic uses of leptin in humans with lipodystrophy and/or diabetes.
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Affiliation(s)
- Hyun-Seuk Moon
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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15
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Abstract
Leptin is secreted into the bloodstream by adipocytes and is required for the maintenance of energy homeostasis and body weight. Leptin deficiency or genetic defects in the components of the leptin signaling pathways cause obesity. Leptin controls energy balance and body weight mainly through leptin receptor b (LEPRb)-expressing neurons in the brain, particularly in the hypothalamus. These LEPRb-expressing neurons function as the first-order neurons that project to the second-order neurons located within and outside the hypothalamus, forming a neural network that controls the energy homeostasis and body weight. Multiple factors, including inflammation and endoplasmic reticulum (ER) stress, contribute to leptin resistance. Leptin resistance is the key risk factor for obesity. This review is focused on recent advance about leptin action, leptin signaling, and leptin resistance.
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16
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Tsou RC, Bence KK. Central regulation of metabolism by protein tyrosine phosphatases. Front Neurosci 2013; 6:192. [PMID: 23308070 PMCID: PMC3538333 DOI: 10.3389/fnins.2012.00192] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/17/2012] [Indexed: 11/13/2022] Open
Abstract
Protein tyrosine phosphatases (PTPs) are important regulators of intracellular signaling pathways via the dephosphorylation of phosphotyrosyl residues on various receptor and non-receptor substrates. The phosphorylation state of central nervous system (CNS) signaling components underlies the molecular mechanisms of a variety of physiological functions including the control of energy balance and glucose homeostasis. In this review, we summarize the current evidence implicating PTPs as central regulators of metabolism, specifically highlighting their interactions with the neuronal leptin and insulin signaling pathways. We discuss the role of a number of PTPs (PTP1B, SHP2, TCPTP, RPTPe, and PTEN), reviewing the findings from genetic mouse models and in vitro studies which highlight these phosphatases as key central regulators of energy homeostasis.
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Affiliation(s)
- Ryan C Tsou
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania Philadelphia, PA, USA
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17
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Johnson JA, Calo S, Nair L, IglayReger HB, Greenwald-Yarnell M, Skorupski J, Myers MG, Bodary PF. Testosterone interacts with the feedback mechanisms engaged by Tyr985 of the leptin receptor and diet-induced obesity. J Steroid Biochem Mol Biol 2012; 132:212-9. [PMID: 22750459 DOI: 10.1016/j.jsbmb.2012.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 06/20/2012] [Accepted: 06/21/2012] [Indexed: 11/24/2022]
Abstract
Inhibitory signaling through Tyr985 of the leptin receptor contributes to the attenuation of anorectic leptin action in obese animals. Leptin receptor (LEPR-B) Tyr985Leu homozygote mutant mice (termed l/l) were previously generated to study Tyr985's contributions to inhibition of LEPR-B signaling; young female l/l mice display a lean, leptin-sensitive phenotype, while young male l/l are not significantly different from wild-type. We report here that testosterone (but not estrogen) determines the sex-specificity of the l/l phenotype. This provides additional insight into the cellular mechanism by which gonadal hormones determine central sensitivity to leptin, and may help elucidate the long-noted sex differences in leptin sensitivity. Additionally, we observed that Tyr985 signaling protects against a diet-dependent switch that exacerbates obesity with high fat feeding, such that the enhanced leptin sensitivity of l/l mice on a normal diet leads to increased adiposity in the face of chronic high-fat diet.
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Affiliation(s)
- Joshua A Johnson
- School of Kinesiology, University of Michigan, 3730 Central Campus Recreational Building, 401 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
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18
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Leptin action via LepR-b Tyr1077 contributes to the control of energy balance and female reproduction. Mol Metab 2012; 1:61-9. [PMID: 24024119 DOI: 10.1016/j.molmet.2012.05.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 05/21/2012] [Accepted: 05/21/2012] [Indexed: 01/10/2023] Open
Abstract
Leptin action in the brain signals the repletion of adipose energy stores, suppressing feeding and permitting energy expenditure on a variety of processes, including reproduction. Leptin binding to its receptor (LepR-b) promotes the tyrosine phosphorylation of three sites on LepR-b, each of which mediates distinct downstream signals. While the signals mediated by LepR-b Tyr1138 and Tyr985 control important aspects of energy homeostasis and LepR-b signal attenuation, respectively, the role of the remaining LepR-b phosphorylation site (Tyr1077) in leptin action has not been studied. To examine the function of Tyr1077, we generated a "knock-in" mouse model expressing LepR-b (F1077), which is mutant for LepR-b Tyr1077. Mice expressing LepR-b (F1077) demonstrate modestly increased body weight and adiposity. Furthermore, females display impairments in estrous cycling. Our results suggest that signaling by LepR-b Tyr1077 plays a modest role in the control of metabolism by leptin, and is an important link between body adiposity and the reproductive axis.
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Key Words
- ARC, arcuate nucleus
- AgRP, agouti-related peptide
- BAT, brown adipose tissue
- Estrus
- HD, high-fat diet
- IVGTT, intravenous glucose tolerance test
- Kiss, kisspeptin
- LepR-b, leptin receptor
- Leptin
- NC, normal chow
- NPY, neuropeptide Y
- Obesity
- PMv, ventral premammilary nucleus
- POMC, proopiomelanocortin
- Reproduction
- STAT5
- STAT5, signal transducer and activator of transcription-5
- TAC2, tachykinin-2
- Tyrosine phosphorylation
- WAT, white adipose tissue
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Effects of aging and caloric restriction on brainstem satiety center signals in rats. Mech Ageing Dev 2012; 133:83-91. [PMID: 22285292 DOI: 10.1016/j.mad.2012.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 12/31/2011] [Accepted: 01/13/2012] [Indexed: 02/02/2023]
Abstract
Age-related increases of body weight and adiposity, indicating dysregulation of food intake/energy expenditure, can be prevented in rodents by long-term 40% caloric restriction. The dorsal vagal complex (DVC), the brainstem center mediating the satiety reflex, has recently emerged as a determinant effector of long-term feeding adaptation. To study the effects of aging and caloric restriction on satiety circuits, leptin and brain-derived neurotrophic factor (BDNF) signaling systems were studied in 2- and 19-month-old ad libitum-fed (AL) and 19-month-old calorie-restricted (CR) rats. Age-induced hyperleptinemia in AL rats was correlated with elevated DVC BDNF immunoreactive concentrations and satiety threshold stability, suggesting functional desensitization of the DVC to these signals. To better understand this phenomenon, mRNA levels of receptor and post-receptor signaling effectors were measured by real-time RT-PCR. Aging selectively increased BDNF receptors and suppressor of cytokine signaling-3 (SOCS-3) mRNA levels. Caloric restriction prevented age-related increases of serum leptin, DVC BDNF and SOCS-3 mRNA levels, but not those of BDNF receptors. In CR rats, prevention of leptin resistance-promoting SOCS-3 induction was also observed at the protein level. This study suggests that leptin post-receptor targets and BDNF signaling play a role in the establishment of age-related DVC dysfunction.
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Obesity and the ageing brain: could leptin play a role in neurodegeneration? Curr Gerontol Geriatr Res 2011; 2011:708154. [PMID: 22013440 PMCID: PMC3195276 DOI: 10.1155/2011/708154] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 08/15/2011] [Indexed: 01/19/2023] Open
Abstract
Obesity and ageing are both characteristics of the human population that are on the increase across the globe. It has long been established that ageing is the major risk factor for neurodegenerative conditions such as Alzheimer's disease, and it is becoming increasingly evident that obesity is another such factor. Leptin resistance or insensitivity has been uncovered as a cause of obesity, and in addition the leptin signalling system is less potent in the elderly. Taken together, these findings reveal that this molecule may be a link between neurodegeneration and obesity or ageing. It is now known that leptin has beneficial effects on both the survival and neurophysiology of the neurons that are lost in Alzheimer's disease suggesting that it may be an important research target in the quest for strategies to prevent, halt, or cure this condition.
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21
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Leptin resistance develops spontaneously in mice during adult life in a tissue-specific manner. Consequences for hepatic steatosis. Biochimie 2011; 93:1779-85. [DOI: 10.1016/j.biochi.2011.06.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 06/17/2011] [Indexed: 12/22/2022]
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Chen Y, Lin X, Liu Y, Xie D, Fang J, Le Y, Ke Z, Zhai Q, Wang H, Guo F, Wang F, Liu Y. Research advances at the Institute for Nutritional Sciences at Shanghai, China. Adv Nutr 2011; 2:428-39. [PMID: 22332084 PMCID: PMC3183593 DOI: 10.3945/an.111.000703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Nutrition-related health issues have emerged as a major threat to public health since the rebirth of the economy in China starting in the 1980s. To meet this challenge, the Chinese Academy of Sciences established the Institute for Nutritional Sciences (INS) at Shanghai, China ≈ 8 y ago. The mission of the INS is to apply modern technologies and concepts in nutritional research to understand the molecular mechanism and provide means of intervention in the combat against nutrition-related diseases, including type 2 diabetes, metabolic syndrome, obesity, cardiovascular diseases, and many types of cancers. Through diligent and orchestrated efforts by INS scientists, graduate students, and research staff in the past few years, the INS has become the leading institution in China in the areas of basic nutritional research and metabolic regulation. Scientists at the INS have made important progress in many areas, including the characterization of genetic and nutritional properties of the Chinese population, metabolic control associated with nutrient sensing, molecular mechanisms underlying glucose and lipid metabolism, regulation of metabolism by adipokines and inflammatory pathways, disease intervention using functional foods or extracts of Chinese herbs, and many biological studies related to carcinogenesis. The INS will continue its efforts in understanding the optimal nutritional needs for Chinese people and the molecular causes associated with metabolic diseases, thus paving the way for effective and individualized intervention in the future. This review highlights the major research endeavors undertaken by INS scientists in recent years.
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Affiliation(s)
- Yan Chen
- Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
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23
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Metlakunta AS, Sahu M, Yasukawa H, Dhillon SS, Belsham DD, Yoshimura A, Sahu A. Neuronal suppressor of cytokine signaling-3 deficiency enhances hypothalamic leptin-dependent phosphatidylinositol 3-kinase signaling. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1185-93. [PMID: 21325649 DOI: 10.1152/ajpregu.00794.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Suppressor of cytokine signaling-3 (SOCS3) is thought to be involved in the development of central leptin resistance and obesity by inhibiting STAT3 pathway. Because phosphatidylinositol 3-kinase (PI3K) pathway plays an important role in transducing leptin action in the hypothalamus, we examined whether SOCS3 exerted an inhibition on this pathway. We first determined whether leptin sensitivity in the hypothalamic PI3K pathway was increased in brain-specific Socs3-deficient (NesKO) mice. In NesKO mice, hypothalamic insulin receptor substrate-1 (IRS1)-associated PI3K activity was significantly increased at 30 min and remained elevated up to 2 h after leptin intraperitoneal injection, but in wild-type (WT) littermates, the significant increase was only at 30 min. Hypothalamic p-STAT3 levels were increased up to 5 h in NesKO as opposed to 2 h in WT mice. In food-restricted WT mice with reduced body weight, leptin increased hypothalamic PI3K activity only at 30 min, and p-STAT3 levels at 30-120 min postinjection. These results suggest increased leptin sensitivity in both PI3K and STAT3 pathways in the hypothalamus of NesKO mice, which was not due to a lean phenotype. In the next experiment with a clonal hypothalamic neuronal cell line expressing proopiomelanocortin, we observed that whereas leptin significantly increased IRS1-associated PI3K activity and p-JAK2 levels in cells transfected with control vector, it failed to do so in SOCS3-overexpressed cells. Altogether, these results imply a SOCS3 inhibition of the PI3K pathway of leptin signaling in the hypothalamus, which may be one of the mechanisms behind the development of central leptin resistance and obesity.
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Affiliation(s)
- Anantha S Metlakunta
- Dept. of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Research Institute, 204 Craft Avenue, Pittsburgh, PA 15213, USA
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24
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Harlan SM, Morgan DA, Dellsperger DJ, Myers MG, Mark AL, Rahmouni K. Cardiovascular and sympathetic effects of disrupting tyrosine 985 of the leptin receptor. Hypertension 2011; 57:627-32. [PMID: 21263121 DOI: 10.1161/hypertensionaha.110.166538] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Leptin acts in the brain to regulate food intake and energy expenditure. Leptin also increases renal sympathetic nerve activity and arterial pressure. The divergent signaling capacities of the leptin receptor (ObRb) mediate the stimulation of various intracellular pathways that are important for leptin control of physiological processes. We evaluated the cardiovascular and sympathetic consequences of disrupting the signal emanating from tyrosine985 of ObRb. For this, we used Lepr(L985) (l/l) mice, which carry a loss of function mutation replacing tyrosine985 of ObRb with leucine. Body weight of l/l mice was not significantly different from wild-type controls. In contrast, radiotelemetry measurements revealed that the l/l mice had higher arterial pressure and heart rate as compared with controls. Ganglionic blockade caused a greater arterial pressure fall in the l/l mice relative to controls. In addition, leptin treatment induced a larger increase in arterial pressure and heart rate in the l/l versus wild-type mice. Finally, we compared the response of renal and brown adipose tissue sympathetic nerve activity to intracerebroventricular injection of leptin (2 μg) between l/l and control mice. Leptin-induced increase in renal sympathetic nerve activity was greater in l/l mice relative to controls. In contrast, the brown adipose tissue sympathetic nerve activity response to leptin was attenuated in the l/l mice relative to controls. These data indicate that selective loss of leptin receptor signaling emanating from tyrosine985 enhances the cardiovascular and renal sympathetic effects of leptin. These findings provide important insight into the molecular mechanisms underlying leptin's effects on the sympathetic cardiovascular function and arterial pressure.
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Affiliation(s)
- Shannon M Harlan
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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25
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Yang CS, Lam CK, Chari M, Cheung GW, Kokorovic A, Gao S, Leclerc I, Rutter GA, Lam TK. Hypothalamic AMP-activated protein kinase regulates glucose production. Diabetes 2010; 59:2435-43. [PMID: 20682691 PMCID: PMC3279556 DOI: 10.2337/db10-0221] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE The fuel sensor AMP-activated protein kinase (AMPK) in the hypothalamus regulates energy homeostasis by sensing nutritional and hormonal signals. However, the role of hypothalamic AMPK in glucose production regulation remains to be elucidated. We hypothesize that bidirectional changes in hypothalamic AMPK activity alter glucose production. RESEARCH DESIGN AND METHODS To introduce bidirectional changes in hypothalamic AMPK activity in vivo, we first knocked down hypothalamic AMPK activity in male Sprague-Dawley rats by either injecting an adenovirus expressing the dominant-negative form of AMPK (Ad-DN AMPKα2 [D(157)A]) or infusing AMPK inhibitor compound C directly into the mediobasal hypothalamus. Next, we independently activated hypothalamic AMPK by delivering either an adenovirus expressing the constitutive active form of AMPK (Ad-CA AMPKα1(312) [T172D]) or the AMPK activator AICAR. The pancreatic (basal insulin)-euglycemic clamp technique in combination with the tracer-dilution methodology was used to assess the impact of alternations in hypothalamic AMPK activity on changes in glucose kinetics in vivo. RESULTS Injection of Ad-DN AMPK into the hypothalamus knocked down hypothalamic AMPK activity and led to a significant suppression of glucose production with no changes in peripheral glucose uptake during the clamps. In parallel, hypothalamic infusion of AMPK inhibitor compound C lowered glucose production as well. Conversely, molecular and pharmacological activation of hypothalamic AMPK negated the ability of hypothalamic nutrients to lower glucose production. CONCLUSIONS These data indicate that changes in hypothalamic AMPK activity are sufficient and necessary for hypothalamic nutrient-sensing mechanisms to alter glucose production in vivo.
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Affiliation(s)
- Clair S. Yang
- Department of Physiology, University of Toronto, Toronto, Canada
- Toronto General Research Institute, University Health Network, Toronto, Canada
| | - Carol K.L. Lam
- Department of Physiology, University of Toronto, Toronto, Canada
- Toronto General Research Institute, University Health Network, Toronto, Canada
| | - Madhu Chari
- Department of Physiology, University of Toronto, Toronto, Canada
- Toronto General Research Institute, University Health Network, Toronto, Canada
| | - Grace W.C. Cheung
- Department of Physiology, University of Toronto, Toronto, Canada
- Toronto General Research Institute, University Health Network, Toronto, Canada
| | - Andrea Kokorovic
- Department of Physiology, University of Toronto, Toronto, Canada
- Toronto General Research Institute, University Health Network, Toronto, Canada
| | - Sun Gao
- Section of Cell Biology, Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Imperial College, South Kensington, London, U.K
| | - Isabelle Leclerc
- Section of Cell Biology, Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Imperial College, South Kensington, London, U.K
| | - Guy A. Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Imperial College, South Kensington, London, U.K
| | - Tony K.T. Lam
- Department of Physiology, University of Toronto, Toronto, Canada
- Toronto General Research Institute, University Health Network, Toronto, Canada
- Department of Medicine, University of Toronto, Toronto, Canada
- Corresponding author: Tony Lam,
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