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Huang T, Lu Z, Wang Z, Cheng L, Gao L, Gao J, Zhang N, Geng CA, Zhao X, Wang H, Wong CW, Yeung KWK, Pan H, Lu WW, Guan M. Targeting adipocyte ESRRA promotes osteogenesis and vascular formation in adipocyte-rich bone marrow. Nat Commun 2024; 15:3769. [PMID: 38704393 PMCID: PMC11069533 DOI: 10.1038/s41467-024-48255-8] [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: 07/18/2023] [Accepted: 04/23/2024] [Indexed: 05/06/2024] Open
Abstract
Excessive bone marrow adipocytes (BMAds) accumulation often occurs under diverse pathophysiological conditions associated with bone deterioration. Estrogen-related receptor α (ESRRA) is a key regulator responding to metabolic stress. Here, we show that adipocyte-specific ESRRA deficiency preserves osteogenesis and vascular formation in adipocyte-rich bone marrow upon estrogen deficiency or obesity. Mechanistically, adipocyte ESRRA interferes with E2/ESR1 signaling resulting in transcriptional repression of secreted phosphoprotein 1 (Spp1); yet positively modulates leptin expression by binding to its promoter. ESRRA abrogation results in enhanced SPP1 and decreased leptin secretion from both visceral adipocytes and BMAds, concertedly dictating bone marrow stromal stem cell fate commitment and restoring type H vessel formation, constituting a feed-forward loop for bone formation. Pharmacological inhibition of ESRRA protects obese mice against bone loss and high marrow adiposity. Thus, our findings highlight a therapeutic approach via targeting adipocyte ESRRA to preserve bone formation especially in detrimental adipocyte-rich bone milieu.
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Affiliation(s)
- Tongling Huang
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Zhaocheng Lu
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Zihui Wang
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lixin Cheng
- Guangdong Provincial Clinical Research Center for Geriatrics, Shenzhen Clinical Research Center for Geriatrics, Shenzhen People's Hospital, Shenzhen, China
| | - Lu Gao
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jun Gao
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Ning Zhang
- Neuroscience Center, Shantou University Medical College, Shantou, China
| | - Chang-An Geng
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Xiaoli Zhao
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Huaiyu Wang
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | | | - Kelvin W K Yeung
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Haobo Pan
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - William Weijia Lu
- Faculty of Pharmaceutical Sciences, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Min Guan
- Research Center for Human Tissues and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
- University of Chinese Academy of Sciences, Beijing, China.
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2
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Purnell JQ, le Roux CW. Hypothalamic control of body fat mass by food intake: The key to understanding why obesity should be treated as a disease. Diabetes Obes Metab 2024; 26 Suppl 2:3-12. [PMID: 38351898 DOI: 10.1111/dom.15478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/06/2024] [Accepted: 01/18/2024] [Indexed: 03/27/2024]
Abstract
BACKGROUND Hypothalamic centres have been recognized to play a central role in body weight regulation for nearly 70 years. AIMS In this review, we will explore the current undersanding of the role the hypothalamus plays in controlling food intake behaviours. MATERIALS AND METHODS Review of relevant literature from PubMed searches and review article citations. RESULTS Beginning with autopsy studies showing destructive hypothalamic lesions in patients manifesting hyperphagia and rapid weight gain, followed by animal lesioning studies pinpointing adjacent hypothalamic sites as the 'satiety' centre and the 'feeding' centre of the brain, the neurocircuitry that governs our body weight is now understood to consist of a complex, interconnected network, including the hypothalamus and extending to cortical sites, reward centres and brainstem. Neurons in these sites receive afferent signals from the gastrointestinal tract and adipose tissue indicating food availability, calorie content, as well as body fat mass. DISCUSSION Integration of these complex signals leads to modulation of the two prime effector systems that defend a body fat mass set point: food intake and energy expenditure. CONCLUSION Understanding the hypothalamic control of food intake forms the foundation for understanding and managing obesity as a chronic disease.
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Affiliation(s)
- Jonathan Q Purnell
- Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Carel W le Roux
- School of Medicine, University College Dublin, Dublin, Ireland
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3
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Nakagawa T, Hosoi T. Recent progress on action and regulation of anorexigenic adipokine leptin. Front Endocrinol (Lausanne) 2023; 14:1172060. [PMID: 37547309 PMCID: PMC10399691 DOI: 10.3389/fendo.2023.1172060] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/06/2023] [Indexed: 08/08/2023] Open
Abstract
Organismal energy balance is controlled by inter-tissue communication mediated by the nervous system and hormones, the disruption of which causes metabolic syndrome exemplified by diabetes and obesity. Fat-storing adipose tissue, especially those located in subcutaneous white adipose tissue, secretes leptin in a proportion of fat mass, inhibiting the accumulation of organismal fat by suppressing appetite and promoting energy expenditure. With a prevalence of obesity that exhibits hyperleptinemia, most of the investigation on leptin has been focused on how it works and how it does not, which is expected to be a clue for treating obesity. In contrast, how it is synthesized, transported, and excreted, all of which are relevant to the homeostasis of blood leptin concentration, are not much understood. Of note, acute leptin reduction after hyperleptinemia in the context of obesity exhibited a beneficial effect on obesity and insulin sensitivity, indicating that manipulation of circulating leptin level may provide a therapeutic strategy. Technological advances such as "omics" analysis combined with sophisticated gene-engineered mice studies in the past decade enabled a deeper understanding of leptin's action in more detail. Here, we summarize the updated understanding of the action as well as regulation of leptin and point out the emerging direction of research on leptin.
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Affiliation(s)
- Tadashi Nakagawa
- Department of Clinical Pharmacology, Faculty of Pharmaceutical Sciences, Sanyo-Onoda City University, Sanyo-Onoda, Yamaguchi, Japan
- Division of Cell Proliferation, ART, Graduate School of Medicine, Tohoku University, Sendai, Miyagi, Japan
| | - Toru Hosoi
- Department of Clinical Pharmacology, Faculty of Pharmaceutical Sciences, Sanyo-Onoda City University, Sanyo-Onoda, Yamaguchi, Japan
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4
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Warashina S, Sato H, Zouda M, Takahashi M, Wada Y, Passioura T, Suga H, Watanabe Y, Matsumoto K, Mukai H. Two-Chain Mature Hepatocyte Growth Factor-Specific Positron Emission Tomography Imaging in Tumors Using 64Cu-Labeled HiP-8, a Nonstandard Macrocyclic Peptide Probe. Mol Pharm 2023; 20:2029-2038. [PMID: 36862642 DOI: 10.1021/acs.molpharmaceut.2c01020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
Two-chain hepatocyte growth factor (tcHGF), the mature form of HGF, is associated with malignancy and anticancer drug resistance; therefore, its quantification is an important indicator for cancer diagnosis. In tumors, activated tcHGF hardly discharges into the systemic circulation, indicating that tcHGF is an excellent target for molecular imaging using positron emission tomography (PET). We recently discovered HGF-inhibitory peptide-8 (HiP-8) that binds specifically to human tcHGF with nanomolar affinity. The purpose of this study was to investigate the usefulness of HiP-8-based PET probes in human HGF knock-in humanized mice. 64Cu-labeled HiP-8 molecules were synthesized using a cross-bridged cyclam chelator, CB-TE1K1P. Radio-high-performance liquid chromatography-based metabolic stability analyses showed that more than 90% of the probes existed in intact form in blood at least for 15 min. In PET studies, significantly selective visualization of hHGF-overexpressing tumors versus hHGF-negative tumors was observed in double-tumor-bearing mice. The accumulation of labeled HiP-8 into the hHGF-overexpressing tumors was significantly reduced by competitive inhibition. In addition, the radioactivity and distribution of phosphorylated MET/HGF receptor were colocalized in tissues. These results demonstrate that the 64Cu-labeled HiP-8 probes are suitable for tcHGF imaging in vivo, and secretory proteins like tcHGF can be a target for PET imaging.
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Affiliation(s)
- Shota Warashina
- Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Hiroki Sato
- Division of Tumor Dynamics and Regulation, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Maki Zouda
- Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Maiko Takahashi
- Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Yasuhiro Wada
- Laboratory for Pathophysiological and Health Science, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Toby Passioura
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Yasuyoshi Watanabe
- Laboratory for Pathophysiological and Health Science, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Kunio Matsumoto
- Division of Tumor Dynamics and Regulation, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.,WPI-Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
| | - Hidefumi Mukai
- Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.,Department of Pharmaceutical Informatics, Graduate School of Biomedical Science, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan
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5
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Ceccarini G, Gilio D, Magno S, Pelosini C, Leverone M, Miceli C, Barison A, Fabiani I, Emdin M, Santini F. Post-acute cardiac complications following SARS-CoV-2 infection in partial lipodystrophy due to LMNA gene p.R349W mutation. J Endocrinol Invest 2022; 45:1569-1575. [PMID: 35384599 PMCID: PMC8984660 DOI: 10.1007/s40618-022-01795-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 03/12/2022] [Accepted: 03/23/2022] [Indexed: 11/08/2022]
Abstract
PURPOSE SARS-CoV-2 infection may cause varying degrees of cardiac injury and the presence of underlying cardiovascular morbidities contributes to the frequency and severity of occurrence of this complication. Lipodystrophy syndromes are frequently characterized by severe metabolic derangements that represent relevant cardiovascular risk factors. Besides causing lipodystrophy, mutations in the lamin A/C (LMNA) gene can lead to a wide spectrum of tissue-specific disorders including cardiac involvement. METHODS AND RESULTS We herein examine the case of two patients affected by atypical progeroid syndrome and partial lipodystrophy due to a heterozygous missense LMNA mutation c.1045 C > T (p.R349W) who presented initially with mild COVID-19 and developed severe cardiovascular complications within few weeks of SARS-CoV-2 infection. Before being infected with SARS-CoV-2, our patients had cardiovascular morbidities (mild mitral regurgitation in one patient, ischemic heart disease with bifascicular block in the other patient) in adjunct to cardiovascular risk factors, but the SARS-CoV-2 infection contributed to quickly and significantly decompensate their balance. CONCLUSION These findings warn that patients affected by LMNA p.R349W mutation and likely other LMNA mutations associated with cardiovascular morbidity should be considered at extremely elevated risk of post-acute cardiological manifestations and should therefore undergo a vigilant follow-up after SARS-CoV-2 infection. Both patients developed COVID-19 before the specific vaccination was available to them and this unfortunate situation should remark the importance of vaccination coverage against SARS-CoV-2 infection for all patients affected by lipodystrophy, especially those with underlying comorbidities.
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Affiliation(s)
- G Ceccarini
- Obesity and Lipodystrophy Center, Endocrinology Unit, University Hospital, Pisa, Italy.
| | - D Gilio
- Obesity and Lipodystrophy Center, Endocrinology Unit, University Hospital, Pisa, Italy
| | - S Magno
- Obesity and Lipodystrophy Center, Endocrinology Unit, University Hospital, Pisa, Italy
| | - C Pelosini
- Chemistry and Endocrinology Laboratory, University Hospital, Pisa, Italy
| | - M Leverone
- Cardiology Unit, Ospedale degli Infermi, Biella, Italy
| | - C Miceli
- Cardiology Unit, Presidio Ospedaliero di Cittadella, Padova, Italy
| | - A Barison
- Fondazione Toscana Gabriele Monasterio, Pisa, Italy
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - I Fabiani
- Fondazione Toscana Gabriele Monasterio, Pisa, Italy
| | - M Emdin
- Fondazione Toscana Gabriele Monasterio, Pisa, Italy
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - F Santini
- Obesity and Lipodystrophy Center, Endocrinology Unit, University Hospital, Pisa, Italy
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6
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He Q, Qin R, Glowacki J, Zhou S, Shi J, Wang S, Gao Y, Cheng L. Synergistic stimulation of osteoblast differentiation of rat mesenchymal stem cells by leptin and 25(OH)D 3 is mediated by inhibition of chaperone-mediated autophagy. Stem Cell Res Ther 2021; 12:557. [PMID: 34717752 PMCID: PMC8557551 DOI: 10.1186/s13287-021-02623-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/07/2021] [Indexed: 11/25/2022] Open
Abstract
Background Vitamin D is important for the mineralization of bones by stimulating osteoblast differentiation of bone marrow mesenchymal stem cells (BMMSCs). BMMSCs are a target of vitamin D action, and the metabolism of 25(OH)D3 to biologically active 1α,25(OH)2D3 in BMMSCs promotes osteoblastogenesis in an autocrine/paracrine manner. Our previous study with human BMMSCs showed that megalin is required for the 25(OH)D3-DBP complex to enter cells and for 25(OH)D3 to stimulate osteoblast differentiation in BMMSCs. Furthermore, we reported that leptin up-regulates megalin in those cells. Leptin is a known inhibitor of PI3K/AKT-dependent chaperone-mediated autophagy (CMA). In this study, we tested the hypothesis that leptin acts synergistically with 25(OH)D3 to promote osteoblastogenesis in rat BMMSCs by a mechanism that entails inhibition of PI3K/AKT-dependent CMA. Methods BMMSCs were isolated from rat bone marrow (4-week-old male SD rats); qRT-PCR and western immunoblots or immunofluorescence were used to evaluate the expression of megalin, ALP, COL1A1, RUNX2, OSX, OSP, and CMA in rBMMSCs. The osteoblast differentiation was evaluated by ALP activity, ALP staining, and calcium deposition. The viability of rBMMSCs was assessed with the CCK-8 kit. Biosynthesis of 1α,25(OH)2D3 was measured by a Rat 1α,25(OH)2D3 ELISA Kit. Results The combination of leptin and 25(OH)D3 treatment significantly enhanced osteoblast differentiation as shown by ALP activity, ALP staining, and calcium deposition, the expression of osteogenic genes ALP, COL1A1, RUNX2, OSX, and OSP by qRT-PCR and western immunoblots in rBMMSCs. Leptin enhanced the expression of megalin and synthesis of 1α,25(OH)2D3 in rBMMSCs. Our data showed that leptin inhibited CMA activity of rBMMSCs by activating PI3K/AKT signal pathway; the ability of leptin to enhance 25(OH)D3 promoted osteoblast differentiation of rBMMSCs was weakened by the PI3K/AKT signal pathway inhibitor. Conclusions Our data reveal the mechanism by which leptin and 25(OH)D3 promote osteoblast differentiation in rBMMSCs. Leptin promoted the expression of megalin by inhibiting CMA, increased the utilization of 25(OH)D3 by rBMMSCs, and enhanced the ability of 25(OH)D3 to induce osteoblast differentiation of rBMMSCs. PI3K/AKT is at least partially involved in the regulation of CMA. These data indicate the importance of megalin in BMMSCs for vitamin D’s role in skeletal health. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-021-02623-z.
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Affiliation(s)
- Qiting He
- Department of Orthopedic Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhuaxi Road, Jinan, 250012, Shandong, People's Republic of China
| | - Ruixi Qin
- Department of Pathology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, People's Republic of China
| | - Julie Glowacki
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Oral and Maxillofacial Surgery, Harvard School of Dental Medicine, Boston, MA, USA
| | - Shuanhu Zhou
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jie Shi
- Department of Orthopedic Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhuaxi Road, Jinan, 250012, Shandong, People's Republic of China
| | - Shaoyi Wang
- Department of Orthopedic Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhuaxi Road, Jinan, 250012, Shandong, People's Republic of China
| | - Yuan Gao
- Department of Orthopedic Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhuaxi Road, Jinan, 250012, Shandong, People's Republic of China.
| | - Lei Cheng
- Department of Orthopedic Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhuaxi Road, Jinan, 250012, Shandong, People's Republic of China.
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7
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O'Brien CJO, Haberman ER, Domingos AI. A Tale of Three Systems: Toward a Neuroimmunoendocrine Model of Obesity. Annu Rev Cell Dev Biol 2021; 37:549-573. [PMID: 34613819 PMCID: PMC7614880 DOI: 10.1146/annurev-cellbio-120319-114106] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The prevalence of obesity is on the rise. What was once considered a simple disease of energy imbalance is now recognized as a complex condition perpetuated by neuro- and immunopathologies. In this review, we summarize the current knowledge of the neuroimmunoendocrine mechanisms underlying obesity. We examine the pleiotropic effects of leptin action in addition to its established role in the modulation of appetite, and we discuss the neural circuitry mediating leptin action and how this is altered with obesity, both centrally (leptin resistance) and in adipose tissues (sympathetic neuropathy). Finally, we dissect the numerous causal and consequential roles of adipose tissue macrophages in obesity and highlight recent key studies demonstrating their direct role in organismal energy homeostasis.
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Affiliation(s)
- Conan J O O'Brien
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom;
| | - Emma R Haberman
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom;
| | - Ana I Domingos
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom;
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8
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Pereira S, Cline DL, Glavas MM, Covey SD, Kieffer TJ. Tissue-Specific Effects of Leptin on Glucose and Lipid Metabolism. Endocr Rev 2021; 42:1-28. [PMID: 33150398 PMCID: PMC7846142 DOI: 10.1210/endrev/bnaa027] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Indexed: 12/18/2022]
Abstract
The discovery of leptin was intrinsically associated with its ability to regulate body weight. However, the effects of leptin are more far-reaching and include profound glucose-lowering and anti-lipogenic effects, independent of leptin's regulation of body weight. Regulation of glucose metabolism by leptin is mediated both centrally and via peripheral tissues and is influenced by the activation status of insulin signaling pathways. Ectopic fat accumulation is diminished by both central and peripheral leptin, an effect that is beneficial in obesity-associated disorders. The magnitude of leptin action depends upon the tissue, sex, and context being examined. Peripheral tissues that are of particular relevance include the endocrine pancreas, liver, skeletal muscle, adipose tissues, immune cells, and the cardiovascular system. As a result of its potent metabolic activity, leptin is used to control hyperglycemia in patients with lipodystrophy and is being explored as an adjunct to insulin in patients with type 1 diabetes. To fully understand the role of leptin in physiology and to maximize its therapeutic potential, the mechanisms of leptin action in these tissues needs to be further explored.
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Affiliation(s)
- Sandra Pereira
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Daemon L Cline
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Scott D Covey
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada.,Department of Surgery, University of British Columbia, Vancouver, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
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9
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Kim DH, Park JW, Jeong HO, Lee B, Chung KW, Lee Y, Jung HJ, Hyun MK, Lee AK, Kim BM, Yu BP, Chung HY. Novel Role of Lck in Leptin-Induced Inflammation and Implications for Renal Aging. Aging Dis 2019; 10:1174-1186. [PMID: 31788330 PMCID: PMC6844581 DOI: 10.14336/ad.2019.0218] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/18/2019] [Indexed: 12/25/2022] Open
Abstract
Aging is associated with increased fat mass and elevated serum leptin levels (hyperleptinemia), causing proinflammation in the kidneys where it plays a primary role in the removal of endogenous leptin from the circulation. Lymphocyte-specific kinase (Lck) is a positive regulator of inflammatory signaling and a potential treatment target for age-related diseases, but its role in leptin signaling is unknown. Here, we investigated how Lck influences hyperleptinemia-induced inflammation in kidney tissues from 6- and 21-month-old rats. Results indicate that Lck expression and activation increased significantly in aged rat kidneys, especially at renal tubules. Furthermore, we identified interactions between Lck and short leptin-receptor isoforms, suggesting that Lck is a protein tyrosine kinase regulating leptin signaling. We further investigated whether increased Lck expression in renal tubular epithelial cells and macrophage infiltration are associated with leptin-induced inflammation. We then demonstrated that leptin activates Lck and proinflammatory transcription factors (STAT3 and NF-κB), while Lck knockdown modulates the expression of both transcription factors. Collectively, these data implicate that Lck leads to development of leptin-induced renal inflammation during aging. Inhibition of this protein tyrosine kinase may therefore be an appropriate therapeutic option for protection against age-related hyperleptinemia.
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Affiliation(s)
- Dae Hyun Kim
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - June Whoun Park
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - Hyoung Oh Jeong
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - Bonggi Lee
- 2Korean Medicine (KM)-Application Center, Korea Institute of Oriental Medicine (KIOM), Daegu 41062, Korea
| | - Ki Wung Chung
- 3Department of Pharmacy, College of Pharmacy, Kyungsung University, Nam-gu, Busan 48434, Korea
| | - Yujeong Lee
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - Hee Jin Jung
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - Min Kyung Hyun
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - A Kyoung Lee
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - Byeong Moo Kim
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
| | - Byung Pal Yu
- 4Department of Physiology, The University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Hae Young Chung
- 1Department of Pharmacy, College of Pharmacy, Pusan National University, Gumjung-gu, Busan 46241, Korea
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10
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Abstract
The discovery of leptin changed the view of adipose tissue from that of a passive vessel that stores fat to that of a dynamic endocrine organ that actively regulates behaviour and metabolism. Secreted by adipose tissue, leptin functions as an afferent signal in a negative feedback loop, acting primarily on neurons in the hypothalamus and regulating feeding and many other functions. The leptin endocrine system serves a critical evolutionary function by maintaining the relative constancy of adipose tissue mass, thereby protecting individuals from the risks associated with being too thin (starvation and infertility) or too obese (predation). In this Review, the biology of leptin is summarized, and a conceptual framework is established for studying the pathogenesis of obesity, which, analogously to diabetes, can result from either leptin hyposecretion or leptin resistance. Herein, these two states are distinguished with the terms 'type 1 obesity' and 'type 2 obesity': type 1 obesity describes a subset of obese individuals with low endogenous plasma leptin levels who respond to leptin therapy, whereas type 2 obesity describes most obese individuals, who are leptin resistant but might respond to leptin therapy in combination with other drugs, such as leptin sensitizers.
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Affiliation(s)
- Jeffrey M Friedman
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
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11
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Rodeheffer MS, Horowitz MC. Fat Decisions: Leptin Regulates Bone versus Fat in the Marrow. Cell Stem Cell 2017; 18:684-686. [PMID: 27257753 DOI: 10.1016/j.stem.2016.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Leptin is an adipocyte-derived hormone involved in energy sensing. In this issue of Cell Stem Cell, Yue et al. (2016) show that leptin is a physiologic signal that acts directly on Leptin-Receptor-expressing mesenchymal stromal cells in adult bone marrow to influence their lineage allocation in vivo, inhibiting bone formation and inducing marrow adipogenesis.
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Affiliation(s)
- Matthew S Rodeheffer
- Department of Molecular, Cell and Developmental Biology, Yale University and the Section of Comparative Medicine, Yale School of Medicine, New Haven, CT 06510, USA.
| | - Mark C Horowitz
- Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT 06510, USA
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12
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D'souza AM, Neumann UH, Glavas MM, Kieffer TJ. The glucoregulatory actions of leptin. Mol Metab 2017; 6:1052-1065. [PMID: 28951828 PMCID: PMC5605734 DOI: 10.1016/j.molmet.2017.04.011] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022] Open
Abstract
Background The hormone leptin is an important regulator of metabolic homeostasis, able to inhibit food intake and increase energy expenditure. Leptin can also independently lower blood glucose levels, particularly in hyperglycemic models of leptin or insulin deficiency. Despite significant efforts and relevance to diabetes, the mechanisms by which leptin acts to regulate blood glucose levels are not fully understood. Scope of review Here we assess literature relevant to the glucose lowering effects of leptin. Leptin receptors are widely expressed in multiple cell types, and we describe both peripheral and central effects of leptin that may be involved in lowering blood glucose. In addition, we summarize the potential clinical application of leptin in regulating glucose homeostasis. Major conclusions Leptin exerts a plethora of metabolic effects on various tissues including suppressing production of glucagon and corticosterone, increasing glucose uptake, and inhibiting hepatic glucose output. A more in-depth understanding of the mechanisms of the glucose-lowering actions of leptin may reveal new strategies to treat metabolic disorders.
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Affiliation(s)
- Anna M D'souza
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Ursula H Neumann
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Surgery, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
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13
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Tam J. The emerging role of the endocannabinoid system in the pathogenesis and treatment of kidney diseases. J Basic Clin Physiol Pharmacol 2017; 27:267-76. [PMID: 26280171 DOI: 10.1515/jbcpp-2015-0055] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 07/22/2015] [Indexed: 12/19/2022]
Abstract
Endocannabinoids (eCBs) are endogenous lipid ligands that bind to cannabinoid receptors that also mediate the effects of marijuana. The eCB system is comprised of eCBs, anandamide, and 2-arachidonoyl glycerol, their cannabinoid-1 and cannabinoid-2 receptors (CB1 and CB2, respectively), and the enzymes involved in their biosynthesis and degradation. It is present in both the central nervous system and peripheral organs including the kidney. The current review focuses on the role of the eCB system in normal kidney function and various diseases, such as diabetes and obesity, that directly contributes to the development of renal pathologies. Normally, activation of the CB1 receptor regulates renal vascular hemodynamics and stimulates the transport of ions and proteins in different nephron compartments. In various mouse and rat models of obesity and type 1 and 2 diabetes mellitus, eCBs generated in various renal cells activate CB1 receptors and contribute to the development of oxidative stress, inflammation, and renal fibrosis. These effects can be chronically ameliorated by CB1 receptor blockers. In contrast, activation of the renal CB2 receptors reduces the deleterious effects of these chronic diseases. Because the therapeutic potential of globally acting CB1 receptor antagonists in these conditions is limited due to their neuropsychiatric adverse effects, the recent development of peripherally restricted CB1 receptor antagonists may represent a novel pharmacological approach in treating renal diseases.
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14
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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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15
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Kwon O, Kim KW, Kim MS. Leptin signalling pathways in hypothalamic neurons. Cell Mol Life Sci 2016; 73:1457-77. [PMID: 26786898 PMCID: PMC11108307 DOI: 10.1007/s00018-016-2133-1] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/20/2015] [Accepted: 01/07/2016] [Indexed: 12/25/2022]
Abstract
Leptin is the most critical hormone in the homeostatic regulation of energy balance among those so far discovered. Leptin primarily acts on the neurons of the mediobasal part of hypothalamus to regulate food intake, thermogenesis, and the blood glucose level. In the hypothalamic neurons, leptin binding to the long form leptin receptors on the plasma membrane initiates multiple signaling cascades. The signaling pathways known to mediate the actions of leptin include JAK-STAT signaling, PI3K-Akt-FoxO1 signaling, SHP2-ERK signaling, AMPK signaling, and mTOR-S6K signaling. Recent evidence suggests that leptin signaling in hypothalamic neurons is also linked to primary cilia function. On the other hand, signaling molecules/pathways mitigating leptin actions in hypothalamic neurons have been extensively investigated in an effort to treat leptin resistance observed in obesity. These include SOCS3, tyrosine phosphatase PTP1B, and inflammatory signaling pathways such as IKK-NFκB and JNK signaling, and ER stress-mitochondrial signaling. In this review, we discuss leptin signaling pathways in the hypothalamus, with a particular focus on the most recently discovered pathways.
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Affiliation(s)
- Obin Kwon
- Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, 05505, Korea
| | - Ki Woo Kim
- Department of Pharmacology, Yonsei University Wonju College of Medicine, Wonju, 26426, Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, 26426, Korea
| | - Min-Seon Kim
- Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea.
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, 05505, Korea.
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16
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Yue R, Zhou BO, Shimada IS, Zhao Z, Morrison SJ. Leptin Receptor Promotes Adipogenesis and Reduces Osteogenesis by Regulating Mesenchymal Stromal Cells in Adult Bone Marrow. Cell Stem Cell 2016; 18:782-796. [PMID: 27053299 DOI: 10.1016/j.stem.2016.02.015] [Citation(s) in RCA: 299] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 01/25/2016] [Accepted: 02/25/2016] [Indexed: 12/24/2022]
Abstract
Skeletal stem cells (SSCs) that are the major source of osteoblasts and adipocytes in adult bone marrow express leptin receptor (LepR). To test whether LepR regulates SSC function, we conditionally deleted Lepr from limb bone marrow stromal cells, but not from the axial skeleton or hypothalamic neurons, using Prx1-Cre. Prx1-Cre;Lepr(fl/fl) mice exhibited normal body mass and normal hematopoiesis. However, limb bones from Prx1-Cre;Lepr(fl/fl) mice exhibited increased osteogenesis, decreased adipogenesis, and accelerated fracture healing. Leptin increased adipogenesis and reduced osteogenesis by activating Jak2/Stat3 signaling in bone marrow stromal cells. A high-fat diet increased adipogenesis and reduced osteogenesis in limb bones from wild-type mice, but not from Prx1-Cre;Lepr(fl/fl) mice. This reflected local effects of LepR on osteogenesis and adipogenesis by bone marrow stromal cells and systemic effects on bone resorption. Leptin/LepR signaling regulates adipogenesis and osteogenesis by mesenchymal stromal cells in the bone marrow in response to diet and adiposity.
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Affiliation(s)
- Rui Yue
- Department of Pediatrics and Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Bo O Zhou
- Department of Pediatrics and Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Issei S Shimada
- Department of Pediatrics and Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zhiyu Zhao
- Department of Pediatrics and Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sean J Morrison
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pediatrics and Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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17
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Schatka I, Weiberg D, Reichelt S, Owsianski-Hille N, Derlin T, Berding G, Bengel FM. A randomized, double-blind, crossover comparison of novel continuous bed motion versus traditional bed position whole-body PET/CT imaging. Eur J Nucl Med Mol Imaging 2015; 43:711-7. [DOI: 10.1007/s00259-015-3226-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/08/2015] [Indexed: 11/29/2022]
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18
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Santoro A, Mattace Raso G, Meli R. Drug targeting of leptin resistance. Life Sci 2015; 140:64-74. [DOI: 10.1016/j.lfs.2015.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/06/2015] [Accepted: 05/13/2015] [Indexed: 12/21/2022]
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19
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Hart RA, Dobos RC, Agnew LL, Tellam RL, McFarlane JR. Pharmacokinetics of leptin in female mice. Physiol Res 2015; 65:311-20. [PMID: 26447522 DOI: 10.33549/physiolres.933053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Pharmacokinetics of leptin in mammals has received limited attention and only one study has examined more than two time points and this was in ob/ob mice. This study is the first to observe the distribution of leptin over a time course in female mice. A physiologic dose (12 ng) of radiolabelled leptin was injected in adult female mice via the lateral tail vein and tissues were dissected out and measured for radioactivity over a time course up to two hours. Major targets for administered leptin included the liver, kidneys, gastrointestinal tract and the skin while the lungs had high concentrations of administered leptin per gram of tissue. Leptin was also found to enter the lumen of the digestive tract intact from the plasma. Very little of the dose (<1 %) was recovered from the brain at any time. Consequently we confirm that the brain is not a major target for leptin from the periphery, although it may be very sensitive to leptin that does get to the hypothalamus. Several of the major targets (GI tract, skin and lungs) for leptin form the interface for the body with the environment, and given the ability of leptin to modulate immune function, this may represent a priming effect for tissues to respond to damage and infection.
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Affiliation(s)
- R A Hart
- Centre for Bioactive Discovery in Health and Ageing, University of New England, Armidale, NSW 2351, Australia.
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20
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Peng Y, Zeng W, Ye H, Han K, Dharmarajan V, Novick S, Wilson I, Griffin P, Friedman J, Lerner R. A General Method for Insertion of Functional Proteins within Proteins via Combinatorial Selection of Permissive Junctions. ACTA ACUST UNITED AC 2015; 22:1134-43. [DOI: 10.1016/j.chembiol.2015.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 06/12/2015] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
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21
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Abstract
In this study we set out to explain the differing effects of parabiosis with genetically diabetic (db) mice versus administration of recombinant leptin. Parabiosis of db mutant, which overexpress leptin, to wildtype (WT) or genetically obese (ob) mice has been reported to cause death by starvation, whereas leptin infusions do not produce lethality at any dose or mode of delivery tested. Leptin is not posttranslationally modified other than a single disulphide bond, raising the possibility that it might require additional factor(s) to exert the maximal appetite-suppressing effect. We reconfirmed the lethal effect of parabiosis of db mutant on WT mice and further showed that this lethality could not be rescued by administration of ghrelin or growth hormone. We then initiated a biochemical fractionation of a high-molecular-weight leptin complex from human plasma and identified clusterin as a major component of this leptin-containing complex. However, in contrast to previous reports, we failed to observe a leptin-potentiating effect of either exogenous or endogenous clusterin, and parabiosis of db clusterin(-/-) double-mutant to WT mice still caused lethality. Intriguingly, in parabiotic pairs of two WT mice, leptin infusion into one of the mice led to an enhanced starvation response during calorie restriction as evidenced by increased plasma ghrelin and growth-hormone levels. Moreover, leptin treatment resulted in death of the parabiotic pairs. These data suggest that the appetite suppression in WT mice after parabiosis to db mutants is the result of induced hyperleptinemia combined with the stress or other aspect(s) of the parabiosis procedure.
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22
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Hutcheson J, Ye Y, Han J, Arriens C, Saxena R, Li QZ, Mohan C, Wu T. Resistin as a potential marker of renal disease in lupus nephritis. Clin Exp Immunol 2015; 179:435-43. [PMID: 25345756 DOI: 10.1111/cei.12473] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2014] [Indexed: 12/13/2022] Open
Abstract
Systemic lupus erythematosus (SLE) and lupus nephritis (LN) have strong concomitance with cardiovascular disease that cannot be explained fully by typical risk factors. We examined the possibility that serum or urine expression of adipokines may act as biomarkers for LN, as these proteins have been associated previously with cardiovascular disease as well as SLE. Antibody arrays were performed on serum and urine from lupus patients and matched controls using a cross-sectional study design. From the initial array-based screening data of 15 adipokines, adiponectin, leptin and resistin were selected for validation by enzyme-linked immunosorbent assay (ELISA). Correlations were determined between adipokine expression levels and measures of disease activity or lupus nephritis. The expression of adiponectin and resistin was increased in both sera and urine from LN patients, while leptin was increased in LN patient sera, compared to matched controls. Serum resistin, but not urine resistin, was correlated with measures of renal dysfunction in LN. Serum resistin expression may be useful as a marker of renal dysfunction in patients with LN, although longitudinal studies are warranted. Further studies are necessary to determine if resistin has functional consequences in LN.
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Affiliation(s)
- J Hutcheson
- University of Texas Southwestern Medical Center, Department of Internal Medicine, Rheumatic Diseases Division, University of Houston, Dallas, USA; Department of Pathology, University of Houston, Dallas, USA
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23
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Osborne DR, Acuff S, Cruise S, Syed M, Neveu M, Stuckey A, Bradley Y. Quantitative and qualitative comparison of continuous bed motion and traditional step and shoot PET/CT. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2014; 5:56-64. [PMID: 25625027 PMCID: PMC4299776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/19/2014] [Indexed: 06/04/2023]
Abstract
New developments in PET/CT technology have enabled the commercial availability of continuous bed motion (CBM) acquisition methods. This technology has some potential performance benefits compared to standard step and shoot (SS) imaging, however, this technology has not been assessed with regard to quantitative and image quality parameters compared to traditional SS techniques. This study seeks to compare clinically relevant quantitative and image quality parameters using CBM and SS data collection methods with the intent of providing assistance in making educated decisions regarding imaging protocol development when using CBM technology versus SS imaging.
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Affiliation(s)
- Dustin R Osborne
- Department of Radiology, University of Tennessee Graduate School of MedicineUSA
| | - Shelley Acuff
- Department of Radiology, University of Tennessee Graduate School of MedicineUSA
| | - Sarah Cruise
- Department of Chemical and Biomolecular Engineering, University of TennesseeUSA
| | - Mumtaz Syed
- Department of Radiology, University of Tennessee Graduate School of MedicineUSA
| | - Melissa Neveu
- Department of Radiology, University of Tennessee Graduate School of MedicineUSA
| | - Alan Stuckey
- Department of Radiology, University of Tennessee Graduate School of MedicineUSA
| | - Yong Bradley
- Department of Radiology, University of Tennessee Graduate School of MedicineUSA
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24
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Santini F, Marzullo P, Rotondi M, Ceccarini G, Pagano L, Ippolito S, Chiovato L, Biondi B. Mechanisms in endocrinology: the crosstalk between thyroid gland and adipose tissue: signal integration in health and disease. Eur J Endocrinol 2014; 171:R137-52. [PMID: 25214234 DOI: 10.1530/eje-14-0067] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Obesity and thyroid diseases are common disorders in the general population and they frequently occur in single individuals. Alongside a chance association, a direct relationship between 'thyroid and obesity' has been hypothesized. Thyroid hormone is an important determinant of energy expenditure and contributes to appetite regulation, while hormones and cytokines from the adipose tissue act on the CNS to inform on the quantity of energy stores. A continuous interaction between the thyroid hormone and regulatory mechanisms localized in adipose tissue and brain is important for human body weight control and maintenance of optimal energy balance. Whether obesity has a pathogenic role in thyroid disease remains largely a matter of investigation. This review highlights the complexity in the identification of thyroid hormone deficiency in obese patients. Regardless of the importance of treating subclinical and overt hypothyroidism, at present there is no evidence to recommend pharmacological correction of the isolated hyperthyrotropinemia often encountered in obese patients. While thyroid hormones are not indicated as anti-obesity drugs, preclinical studies suggest that thyromimetic drugs, by targeting selected receptors, might be useful in the treatment of obesity and dyslipidemia.
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Affiliation(s)
- Ferruccio Santini
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Paolo Marzullo
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Mario Rotondi
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Giovanni Ceccarini
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Loredana Pagano
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Serena Ippolito
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Luca Chiovato
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Bernadette Biondi
- Endocrinology UnitObesity Center, University Hospital of Pisa, Pisa, ItalyDepartment of Translational MedicineUniversity of Piemonte Orientale, Novara, ItalyDivision of General MedicineI.R.C.C.S. Istituto Auxologico Italiano, Verbania, ItalyUnit of Internal Medicine and EndocrinologyFondazione Salvatore Maugeri I.R.C.C.S., University of Pavia, Pavia, ItalyDepartment of Clinical Medicine and SurgeryUniversity of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
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25
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Zabeau L, Jensen CJ, Seeuws S, Venken K, Verhee A, Catteeuw D, van Loo G, Chen H, Walder K, Hollis J, Foote S, Morris MJ, Van der Heyden J, Peelman F, Oldfield BJ, Rubio JP, Elewaut D, Tavernier J. Leptin's metabolic and immune functions can be uncoupled at the ligand/receptor interaction level. Cell Mol Life Sci 2014; 72:629-644. [PMID: 25098352 PMCID: PMC4293488 DOI: 10.1007/s00018-014-1697-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/17/2014] [Accepted: 07/28/2014] [Indexed: 01/21/2023]
Abstract
The adipocyte-derived cytokine leptin acts as a metabolic switch, connecting the body's metabolism to high-energy consuming processes such as reproduction and immune responses. We here provide genetic and biochemical evidence that the metabolic and immune functions of leptin can be uncoupled at the receptor level. First, homozygous mutant fatt/fatt mice carry a spontaneous splice mutation causing deletion of the leptin receptor (LR) immunoglobulin-like domain (IGD) in all LR isoforms. These mice are hyperphagic and morbidly obese, but display only minimal changes in size and cellularity of the thymus, and cellular immune responses are unaffected. These animals also displayed liver damage in response to concavalin A comparable to wild-type and heterozygous littermates. Second, treatment of healthy mice with a neutralizing nanobody targeting IGD induced weight gain and hyperinsulinaemia, but completely failed to block development of experimentally induced autoimmune diseases. These data indicate that leptin receptor deficiency or antagonism profoundly affects metabolism, with little concomitant effects on immune functions.
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Affiliation(s)
- Lennart Zabeau
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium
| | - Cathy J Jensen
- Neurogenetics Laboratory, Howard Florey Institute, Melbourne, Australia.,Department of Physiology, Monash University, Melbourne, Australia
| | - Sylvie Seeuws
- Laboratory for Molecular Immunology and Inflammation, Department of Rheumatology, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Koen Venken
- Laboratory for Molecular Immunology and Inflammation, Department of Rheumatology, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Annick Verhee
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium
| | - Dominiek Catteeuw
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium
| | - Geert van Loo
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, Faculty of Sciences, Flanders Institute for Biotechnology, Ghent University, Ghent, Belgium
| | - Hui Chen
- Department of Pharmacology, University of Melbourne, Melbourne, Australia
| | - Ken Walder
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Jacob Hollis
- Department of Physiology, Monash University, Melbourne, Australia
| | - Simon Foote
- Menzies Research Institute, Hobart, Australia
| | - Margaret J Morris
- Department of Pharmacology, University of Melbourne, Melbourne, Australia
| | - José Van der Heyden
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium
| | - Frank Peelman
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium
| | - Brian J Oldfield
- Department of Physiology, Monash University, Melbourne, Australia
| | - Justin P Rubio
- Neurogenetics Laboratory, Howard Florey Institute, Melbourne, Australia
| | - Dirk Elewaut
- Laboratory for Molecular Immunology and Inflammation, Department of Rheumatology, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Jan Tavernier
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium.
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Felizardo RJF, Silva MBD, Aguiar CF, Câmara NOS. Obesity in kidney disease: A heavyweight opponent. World J Nephrol 2014; 3:50-63. [PMID: 25332896 PMCID: PMC4202492 DOI: 10.5527/wjn.v3.i3.50] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 04/18/2014] [Accepted: 06/11/2014] [Indexed: 02/05/2023] Open
Abstract
Obesity is an important worldwide challenge that must be faced in most developed and developing countries because of unhealthy nutritional habits. The consequences of obesity and being overweight are observed in different organs, but the kidney is one of the most affected. Excess adipose tissue causes hemodynamic alterations in the kidney that can result in renal disease. However, obesity is also commonly associated with other comorbidities such as chronic inflammation, hypertension and diabetes. This association of several aggravating factors is still a matter of concern in clinical and basic research because the pathophysiologic mechanisms surrounding chronic kidney disease development in obese patients remain unclear. This review will discuss the consequences of obesity in the context of renal injury.
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Abstract
The fat‐derived hormone, leptin, is well known to regulate body weight. However, there is now substantial evidence that leptin also plays a primary role in the regulation of glucose homeostasis, independent of actions on food intake, energy expenditure or body weight. As such, leptin might have clinical utility in treating hyperglycemia, particularly in conditions of leptin deficiency, such as lipodystrophy and diabetes mellitus. The mechanisms through which leptin modulates glucose metabolism have not been fully elucidated. Leptin receptors are widely expressed in peripheral tissues, including the endocrine pancreas, liver, skeletal muscle and adipose, and both direct and indirect leptin action on these tissues contributes to the control of glucose homeostasis. Here we review the role of leptin in glucose homeostasis, along with our present understanding of the mechanisms involved. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00203.x, 2012)
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Affiliation(s)
- Heather C Denroche
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, The Life Sciences Institute ; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
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Byun K, Gil SY, Namkoong C, Youn BS, Huang H, Shin MS, Kang GM, Kim HK, Lee B, Kim YB, Kim MS. Clusterin/ApoJ enhances central leptin signaling through Lrp2-mediated endocytosis. EMBO Rep 2014; 15:801-8. [PMID: 24825475 DOI: 10.15252/embr.201338317] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Hypothalamic leptin signaling plays a central role in maintaining body weight homeostasis. Here, we show that clusterin/ApoJ, recently identified as an anorexigenic neuropeptide, is an important regulator in the hypothalamic leptin signaling pathway. Coadministration of clusterin potentiates the anorexigenic effect of leptin and boosts leptin-induced hypothalamic Stat3 activation. In cultured neurons, clusterin enhances receptor binding and subsequent endocytosis of leptin. These effects are mainly mediated through the LDL receptor-related protein-2 (Lrp2). Notably, inhibition of hypothalamic clusterin, Lrp2 or endocytosis abrogates anorexia and hypothalamic Stat3 activation caused by leptin. These findings propose a novel regulatory mechanism in central leptin signaling pathways.
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Affiliation(s)
- Kyunghee Byun
- Center for Genomics and Proteomics, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - So Young Gil
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Churl Namkoong
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Byung-Soo Youn
- Department of Anatomy, Wonkwang University School of Medicine, Iksan, Korea
| | - Hu Huang
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Mi-Seon Shin
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Gil Myoung Kang
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Hyun-Kyong Kim
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Bonghee Lee
- Center for Genomics and Proteomics, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - Young-Bum Kim
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Min-Seon Kim
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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Liu Z, Hundal-Jabal N, Wong M, Yapp D, Lin KS, Bénard F, Perrin DM. A new18F-heteroaryltrifluoroborate radio-prosthetic with greatly enhanced stability that is labelled by18F–19F-isotope exchange in good yield at high specific activity. MEDCHEMCOMM 2014. [DOI: 10.1039/c3md00328k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Hsuchou H, Jayaram B, Kastin AJ, Wang Y, Ouyang S, Pan W. Endothelial cell leptin receptor mutant mice have hyperleptinemia and reduced tissue uptake. J Cell Physiol 2013; 228:1610-6. [PMID: 23359322 DOI: 10.1002/jcp.24325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/14/2013] [Indexed: 11/10/2022]
Abstract
Hyperleptinemia is usually associated with obesity and leptin resistance. Endothelial cell leptin receptor knockout (ELKO) mice without a signaling membrane-bound leptin receptor in endothelia, however, have profound hyperleptinemia without signs of leptin resistance. Leptin mRNA in adipose tissue was unchanged. To test the hypothesis that the ELKO mutation results in delayed degradation and slowed excretion, we determined the kinetics of leptin transfer in groups of ELKO and wildtype mice after intravenous bolus injection of (125) I-leptin and the reference substance (131) I-albumin. The degradation pattern of (125) I-leptin in serum and brain homogenates at different time points between 10 and 60 min was measured by HPLC and acid precipitation. Although ELKO mice had reduced uptake of (125) I-leptin uptake by the brain and several peripheral organs, leptin was more stable in blood and tissue. There was no change in the rate of renal excretion. ELISA showed that serum soluble leptin receptor, known to antagonize leptin transport, had a 400-fold increase, probably contributing to the hyperleptinemia and reduced tissue uptake. Thus, the ELKO mutation unexpectedly increased the stability of leptin but suppressed its tissue uptake. These changes probably contribute to the known partial resistance of the ELKO mice to diet-induced obesity.
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Affiliation(s)
- Hung Hsuchou
- Blood-Brain Barrier Group, Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA
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Single step 18F-labeling of dimeric cycloRGD for functional PET imaging of tumors in mice. Nucl Med Biol 2013; 40:959-66. [PMID: 24090672 DOI: 10.1016/j.nucmedbio.2013.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 07/31/2013] [Accepted: 08/01/2013] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Arylboronates afford rapid aqueous (18)F-labeling via the creation of a highly polar (18)F-aryltrifluoroborate anion ((18)F-ArBF3(-)). HYPOTHESIS Radiosynthesis of an (18)F-ArBF3(-) can be successfully applied to a clinically relevant peptide. To test this hypothesis, we labeled dimeric-cylcoRGD, [c(RGDfK)]2E because a) it is molecularly complex and provides a challenging substrate to test the application of this technique, and b) [c(RGDfK)]2E has already been labeled via several (18)F-labeling methods which provide for a preliminary comparison. GOAL To validate this labeling method in the context of a complex and clinically relevant tracer to show tumor-specific uptake ex vivo with representative PET images in vivo. METHODS An arylborimidine was conjugated to [c(RGDfK)]2E to give the precursor [c(RGDfK)]2E-ArB(dan), which was aliquoted and stored at -20 °C. Aliquots of 10 or 25 nmol, containing only micrograms of precursor, were labeled using relatively low levels of (18)F-activity. Following purification eight mice (pre-blocked/unblocked) with U87M xenograft tumors were injected with [c(RGDfK)]2E-(18)F-ArBF3(-) (n = 4) for ex vivo tissue dissection. Two sets of mice (pre-blocked/unblocked) were also imaged with PET-CT (n = 2). RESULTS The [c(RGDfK)]2E-ArB(dan) is converted within 15 min to [c(RGDfK)]2E-(18)F-ArBF3(-) in isolated radiochemical yields of ~10% (n = 3) at a minimum effective specific activity of 0.3 Ci/μmol. Biodistribution shows rapid clearance to the bladder via the kidney resulting in high tumor-to-blood and tumor-to-muscle ratios of >9 and >6 respectively while pre-blocking with [c(RGDfK)]2E showed high tumor specificity. PET imaging showed good contrast between tumor and non-target tissues confirming the biodistribution data. CONCLUSION An arylborimidine-RGD peptide is rapidly (18)F-labeled in one step, in good yield, at useful specific activity. Biodistribution studies with blocking controls show tumor specificity, which is corroborated by PET images. Advances in Knowledge and Implications for patient Care: Despite many antecedent examples of labeled RGD tracers, this work is the first to show direct aqueous labeling of bisRGD with an (18)F-ArBF3(-). Labeling occurs in near record rapidity (45 min) at useful effective specific activities and competitive yields for high contrast tumor specific images. As bisRGD has been imaged in humans with several prosthetics, this work suggests potential clinical applications of tracers appended with an (18)F-ArBF3(-). More generally, the ability to label a molecularly complex tracer suggests that this method could be useful to label many other peptides. Furthermore, these results portend the development of kits that use only microgram quantities of lyophilized precursor for on demand labeling. The ability to perform one-step aqueous labeling in under an hour to provide tracers with high T:NT ratios has important implications for developing radiotracers for use in fundamental research and in preclinical tracer studies.
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Li Z, Ceccarini G, Eisenstein M, Tan K, Friedman JM. Phenotypic effects of an induced mutation of the ObRa isoform of the leptin receptor. Mol Metab 2013; 2:364-75. [PMID: 24327953 DOI: 10.1016/j.molmet.2013.07.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 12/14/2022] Open
Abstract
Leptin receptors play critical roles in mediating leptin's pleiotropic effects on mammalian physiology. To date, six splice variants of the leptin receptor gene have been identified [1-3]. These splice variants have identical extracellular leptin binding motifs but different intracellular C termini. The finding that mutations specifically ablating the function of ObRb cause obesity has established a critical role for this isoform in leptin signaling [1,7]. ObRa is the most abundant splicing isoform with a broad tissue distribution [5], and it has been proposed to play roles in regulating leptin bioavailability, CSF (cerebrospinal fluid) transport and function by forming heterodimers with ObRb and also activating signal transduction via JAK2 in-vitro [5-10]. To assess the in-vivo role of ObRa, we generated an ObRa KO mouse by deleting the ObRa-specific exon 19a. Homozygous mutant mice breed normally and are indistinguishable from wild-type mice on regular chow diet, but show a slightly increased basal plasma leptin, a slight improvement of their GTT and a slightly reduced response to systemic leptin administration. These mice also show a modest but statistically significant increase in weight when placed on a high fat diet with a slightly reduced CSF/plasma ratio of leptin. These data suggest that ObRa plays a role in mediating some of leptin's effects but that the phenotypic consequences are modest compared to a deletion of ObRb.
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Affiliation(s)
- Zhiying Li
- The Rockefeller University, 1230 York Avenue, NY 10065, USA
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Nasrallah MP, Ziyadeh FN. Overview of the physiology and pathophysiology of leptin with special emphasis on its role in the kidney. Semin Nephrol 2013; 33:54-65. [PMID: 23374894 DOI: 10.1016/j.semnephrol.2012.12.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The adipocyte product leptin is a pleiotropic adipokine and hormone, with a role extending beyond appetite suppression and increased energy expenditure. This review summarizes the biology of the leptin system and the roles of its different receptors in a multitude of cellular functions in different organs, with special emphasis on the kidney. Leptin's physiological functions as well as deleterious effects in states of leptin deficiency or hyperleptinemia are emphasized. Chronic hyperleptinemia can increase blood pressure through the sympathetic nervous system and renal salt retention. The concept of selective leptin resistance in obesity is emerging, whereby leptin's effect on appetite and energy expenditure is blunted, with a concomitant increase in leptin's other effects as a result of the accompanying hyperleptinemia. The divergence in response likely is explained by different receptors and post-receptor activating mechanisms. Chronic kidney disease is a known cause of hyperleptinemia. There is an emerging view that the effect of hyperleptinemia on the kidney can contribute to the development and/or progression of chronic kidney disease in selective resistance states such as in obesity or type 2 diabetes mellitus. The mechanisms of renal injury are likely the result of exaggerated and undesirable hemodynamic influences as well as profibrotic effects.
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Affiliation(s)
- Mona P Nasrallah
- Department of Internal Medicine, American University of Beirut, Beirut, Lebanon.
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Liu Z, Li Y, Lozada J, Wong MQ, Greene J, Lin KS, Yapp D, Perrin DM. Kit-like 18F-labeling of RGD-19F-arytrifluroborate in high yield and at extraordinarily high specific activity with preliminary in vivo tumor imaging. Nucl Med Biol 2013; 40:841-9. [PMID: 23810487 DOI: 10.1016/j.nucmedbio.2013.05.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 05/01/2013] [Accepted: 05/07/2013] [Indexed: 02/01/2023]
Abstract
INTRODUCTION Positron Emission Tomography (PET) is a rapidly expanding, cutting edge technology for preclinical evaluation, cancer diagnosis and staging, and patient management. A one-step aqueous (18)F-labeling method, which can be applied to peptides to provide functional in vivo images, has been a long-standing challenge in PET imaging. Over the past few years, we have sought a rapid and mild radiolabeling method based on the aqueous radiosynthesis of in vivo stable aryltrifluoroborate (ArBF(3)(-)) conjugates. Recent access to production levels of (18)F-Fluoride led to a fluorescent-(18)F-ArBF(3)(-) at unprecedentedly high specific activities of 15Ci/μmol. However, extending this method to labeling peptides as imaging agents has not been explored. METHODS In order to extend these results to a peptide of clinical interest in the context of production-level radiosynthesis, we applied this new technology for labeling RGD, measured its specific activity by standard curve analysis, and carried out a preliminary evaluation of its imaging properties. RESULTS RGD was labeled in excellent radiochemical yields at exceptionally high specific activity (~14Ci/μmol) (n = 3). Preliminary tumor-specific images corroborated by ex vivo biodistribution data with blocking controls show statistically significant albeit relatively low tumor uptake along with reasonably high tumor:blood ratios (n = 3). CONCLUSIONS Isotope exchange on a clinically useful (18)F-ArBF(3)(-) radiotracer leads to excellent radiochemical yields and exceptionally high specific activities while the anionic nature of the aryltrifluoroborate prosthetic results in very rapid clearance. Since rapid clearance of the radioactive tracer is generally desirable for tracer development, these results suggest new directions for varying linker arm composition to slightly retard clearance rather than enhancing it. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE This work is the first to use production levels of (18)F-activity to directly label RGD at specific activities that are an order of magnitude higher than most reports and thereby increases the distribution window for radiotracer production and delivery.
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Affiliation(s)
- Zhibo Liu
- Chemistry Department, 2036 Main Mall, University of British Columbia, Vancouver, B.C., Canada
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35
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Clusterin and LRP2 are critical components of the hypothalamic feeding regulatory pathway. Nat Commun 2013; 4:1862. [DOI: 10.1038/ncomms2896] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 04/16/2013] [Indexed: 11/09/2022] Open
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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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Scherer T, Lehnert H, Hallschmid M. Brain insulin and leptin signaling in metabolic control: from animal research to clinical application. Endocrinol Metab Clin North Am 2013; 42:109-25. [PMID: 23391243 DOI: 10.1016/j.ecl.2012.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Besides the well-characterized effects of brain insulin and leptin in regulating food intake, insulin and leptin signaling to the central nervous system modulates a variety of metabolic processes, such as glucose and lipid homeostasis, as well as energy expenditure. This review summarizes the current literature on the contribution of central nervous insulin and leptin action to metabolic control in animals and humans. Potential therapeutic options based on the direct delivery of these peptides to the brain by, for example, intranasal administration, are discussed.
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Affiliation(s)
- Thomas Scherer
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna 1090, Austria.
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Li Y, Guo J, Tang S, Lang L, Chen X, Perrin DM. One-step and one-pot-two-step radiosynthesis of cyclo-RGD-(18)F-aryltrifluoroborate conjugates for functional imaging. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2013; 3:44-56. [PMID: 23342300 PMCID: PMC3545361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 09/22/2012] [Indexed: 06/01/2023]
Abstract
Arylboronates capture aqueous (18)F-fluoride in one step to afford a highly polar (18)F-labeled aryltrifluoroborate anion ((18)F-ArBF(3) (-)) that clears rapidly in vivo. To date however, there is little data to show that a ligand labeled with a prosthetic (18)F-ArBF(3) (-) will provide functional images. RGD, a high-affinity ligand for integrins that are present on the cell surface of numerous tumors, has been labeled in many formats with many different radionuclides, and as such represents a well-established ligand that can be used to evaluate new labeling methods. Herein we have labeled RGD with a prosthetic (18)F-ArBF(3) (-) via two approaches for the first time: 1) a RGD-boronate bioconjugate is directly labeled in one step and 2) an alkyne-modified arylborimidine is first converted to the corresponding (18)F-ArBF(3) (-) which is then conjugated to an RGD-azide via Cu(+)-mediated [2+3] dipolar cycloaddition in one pot over two steps. RGD-(18)F-ArBF(3) (-) bionconjugates were produced in reasonable radiochemical yields using low amounts of (18)F-fluoride anion (10-50 mCi). Despite relatively low specific activities, good tumor images are revealed in each case.
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Affiliation(s)
- Ying Li
- Department of Chemistry, University of British Columbia2036 Main Mall, Vancouver, B.C., V6T-1Z1, Canada
| | - Jinxia Guo
- Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health (NIH)31 Center Drive, Suite 1C14, Bethesda, MD 20892-2281, USA
| | - Shiqing Tang
- Department of Chemistry, University of British Columbia2036 Main Mall, Vancouver, B.C., V6T-1Z1, Canada
| | - Lixin Lang
- Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health (NIH)31 Center Drive, Suite 1C14, Bethesda, MD 20892-2281, USA
| | - Xiaoyuan Chen
- Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health (NIH)31 Center Drive, Suite 1C14, Bethesda, MD 20892-2281, USA
| | - David M Perrin
- Department of Chemistry, University of British Columbia2036 Main Mall, Vancouver, B.C., V6T-1Z1, Canada
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Liu Q, Dalman M, Chen Y, Akhter M, Brahmandam S, Patel Y, Lowe J, Thakkar M, Gregory AV, Phelps D, Riley C, Londraville RL. Knockdown of leptin A expression dramatically alters zebrafish development. Gen Comp Endocrinol 2012; 178:562-72. [PMID: 22841760 PMCID: PMC3428433 DOI: 10.1016/j.ygcen.2012.07.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 07/05/2012] [Accepted: 07/09/2012] [Indexed: 01/13/2023]
Abstract
Using morpholino antisense oligonucleotide (MO) technology, we blocked leptin A or leptin receptor expression in embryonic zebrafish, and analyzed consequences of leptin A knock-down on fish development. Embryos injected with leptin A or leptin receptor MOs (leptin A or leptin receptor morphants) had smaller bodies and eyes, undeveloped inner ear, enlarged pericardial cavity, curved body and/or tail and larger yolk compared to control embryos of the same stages. The defects persisted in 6-9 days old larvae. We found that blocking leptin A function had little effect on the development of early brain (1 day old), but differentiation of both the morphant dorsal brain and retinal cells was severely disrupted in older (2 days old) embryos. Despite the enlarged pericardial cavity, differentiation of cardiac cells appeared to be similar to control embryos. Formation of the morphants' inner ear is also severely disrupted, which corroborates existing reports of leptin receptor expression in inner ear of both zebrafish and mammals. Co-injection of leptin A MO and recombinant leptin results in partial rescue of the wild-type phenotype. Our results suggest that leptin A plays distinct roles in zebrafish development.
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Affiliation(s)
- Qin Liu
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Mark Dalman
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Yun Chen
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Mashal Akhter
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Sravya Brahmandam
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Yesha Patel
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Josef Lowe
- Northeast Ohio Medical University, Rootstown, OH 44272
| | | | - Akil-Vuai Gregory
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Daryllanae Phelps
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Caitlin Riley
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
| | - Richard L. Londraville
- Department of Biology and Program in Integrated Bioscience, University of Akron, Akron, OH 44325
- To whom correspondence should be addressed: Phone: 330-972-7151; Fax: 330-972-8445;
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Tam J, Cinar R, Liu J, Godlewski G, Wesley D, Jourdan T, Szanda G, Mukhopadhyay B, Chedester L, Liow JS, Innis RB, Cheng K, Rice KC, Deschamps JR, Chorvat RJ, McElroy JF, Kunos G. Peripheral cannabinoid-1 receptor inverse agonism reduces obesity by reversing leptin resistance. Cell Metab 2012; 16:167-79. [PMID: 22841573 PMCID: PMC3832894 DOI: 10.1016/j.cmet.2012.07.002] [Citation(s) in RCA: 266] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 04/16/2012] [Accepted: 07/06/2012] [Indexed: 12/13/2022]
Abstract
Obesity-related leptin resistance manifests in loss of leptin's ability to reduce appetite and increase energy expenditure. Obesity is also associated with increased activity of the endocannabinoid system, and CB(1) receptor (CB(1)R) inverse agonists reduce body weight and the associated metabolic complications, although adverse neuropsychiatric effects halted their therapeutic development. Here we show that in mice with diet-induced obesity (DIO), the peripherally restricted CB(1)R inverse agonist JD5037 is equieffective with its brain-penetrant parent compound in reducing appetite, body weight, hepatic steatosis, and insulin resistance, even though it does not occupy central CB(1)R or induce related behaviors. Appetite and weight reduction by JD5037 are mediated by resensitizing DIO mice to endogenous leptin through reversing the hyperleptinemia by decreasing leptin expression and secretion by adipocytes and increasing leptin clearance via the kidney. Thus, inverse agonism at peripheral CB(1)R not only improves cardiometabolic risk in obesity but has antiobesity effects by reversing leptin resistance.
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Affiliation(s)
- Joseph Tam
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
- Correspondence: (J.T.), (G.K.)
| | - Resat Cinar
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jie Liu
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Grzegorz Godlewski
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Daniel Wesley
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tony Jourdan
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gergö Szanda
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bani Mukhopadhyay
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lee Chedester
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert B. Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kejun Cheng
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kenner C. Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | - George Kunos
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
- Correspondence: (J.T.), (G.K.)
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Levi J, Huynh FK, Denroche HC, Neumann UH, Glavas MM, Covey SD, Kieffer TJ. Hepatic leptin signalling and subdiaphragmatic vagal efferents are not required for leptin-induced increases of plasma IGF binding protein-2 (IGFBP-2) in ob/ob mice. Diabetologia 2012; 55:752-62. [PMID: 22202803 DOI: 10.1007/s00125-011-2426-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 11/28/2011] [Indexed: 01/19/2023]
Abstract
AIMS/HYPOTHESIS The fat-derived hormone leptin plays a crucial role in the maintenance of normal body weight and energy expenditure as well as in glucose homeostasis. Recently, it was reported that the liver-derived protein, insulin-like growth factor binding protein-2 (IGFBP-2), is responsible for at least some of the glucose-normalising effects of leptin. However, the exact mechanism by which leptin upregulates IGFBP-2 production is unknown. Since it is believed that circulating IGFBP-2 is predominantly derived from the liver and leptin has been shown to have both direct and indirect actions on the liver, we hypothesised that leptin signalling in hepatocytes or via brain-liver vagal efferents may mediate leptin control of IGFBP-2 production. METHODS To address our hypothesis, we assessed leptin action on glucose homeostasis and plasma IGFBP-2 levels in both leptin-deficient ob/ob mice with a liver-specific loss of leptin signalling and ob/ob mice with a subdiaphragmatic vagotomy. We also examined whether restoring hepatic leptin signalling in leptin receptor-deficient db/db mice could increase plasma IGFBP-2 levels. RESULTS Continuous leptin administration increased plasma IGFBP-2 levels in a dose-dependent manner, in association with reduced plasma glucose and insulin levels. Interestingly, leptin was still able to increase plasma IGFBP-2 levels and improve glucose homeostasis in both ob/ob mouse models to the same extent as their littermate controls. Further, restoration of hepatic leptin signalling in db/db mice did not increase either hepatic or plasma IGFBP-2 levels. CONCLUSIONS/INTERPRETATION Taken together, these data indicate that hepatic leptin signalling and subdiaphragmatic vagal inputs are not required for leptin upregulation of plasma IGFBP-2 nor blood glucose lowering in ob/ob mice.
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Affiliation(s)
- J Levi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
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Pan W, Hsuchou H, Cornelissen-Guillaume GG, Jayaram B, Wang Y, Tu H, Halberg F, Wu X, Chua SC, Kastin AJ. Endothelial leptin receptor mutation provides partial resistance to diet-induced obesity. J Appl Physiol (1985) 2012; 112:1410-8. [PMID: 22323652 DOI: 10.1152/japplphysiol.00590.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Leptin, a polypeptide hormone produced mainly by adipocytes, has diverse effects in both the brain and peripheral organs, including suppression of feeding. Other than mediating leptin transport across the blood-brain barrier, the role of the endothelial leptin receptor remains unclear. We recently generated a mutant mouse strain lacking endothelial leptin receptor signaling, and showed that there is an increased uptake of leptin by brain parenchyma after its delivery by in situ brain perfusion. Here, we tested the hypothesis that endothelial leptin receptor mutation confers partial resistance to diet-induced obesity. These ELKO mice had similar body weight and percent fat as their wild-type littermates when fed with rodent chow, but blood concentrations of leptin were significantly elevated. In response to a high-fat diet, wild-type mice had a greater gain of body weight and fat than ELKO mice. As shown by metabolic chamber measurement, the ELKO mice had higher oxygen consumption, carbon dioxide production, and heat dissipation, although food intake was similar to that of the wild-type mice and locomotor activity was even reduced. This indicates that the partial resistance to diet-induced obesity was mediated by higher metabolic activity in the ELKO mice. Since neuronal leptin receptor knockout mice show obesity and diabetes, the results suggest that endothelial leptin signaling shows opposite effects from that of neuronal leptin signaling, with a facilitatory role in diet-induced obesity.
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Affiliation(s)
- Weihong Pan
- Blood-Brain Barrier Group, Pennington Biomedical Research Center, 6400 Perkins Rd., Baton Rouge, LA 70808, USA.
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Abstract
The cloning of the ob gene and its gene product, leptin, has led to the elucidation of a robust physiologic system that maintains fat stores at a relatively constant level. Leptin is a peptide hormone secreted by adipose tissue in proportion to its mass. Recessive mutations in the leptin gene are associated with massive obesity in mice and humans, establishing a genetic basis for obesity. Leptin circulates in blood and acts on the brain to regulate food intake and energy expenditure. When fat mass falls, plasma leptin levels fall, stimulating appetite and suppressing energy expenditure until fat mass is restored. When fat mass increases, leptin levels increase, suppressing appetite until weight is lost. This system maintains homeostatic control of adipose tissue mass. The discovery of leptin has advanced our understanding of metabolic disease in a number of respects. Its identification has revealed a new endocrine system regulating body weight. This system provides a means by which changes in nutritional state regulate other physiologic systems. A number of leptin deficiency syndromes that are treatable with leptin replacement have been identified. The majority of obese subjects are leptin resistant, which establishes that obesity is the result of hormone resistance. Leptin treatment results in weight loss in a subset of obese patients and can also synergize with other anti-obesity agents to reduce weight in the general population. Leptin provides an entry point for studying a complex human behavior. Finally, this research has established that there is a powerful biological basis for obesity, a fact that is (correctly) changing public perception about the pathogenesis of this medical condition.
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Impact of coenzyme Q10 on the histological structure and immunohistochemical localization of leptin in the ampulla of rat oviduct after monosodium glutamate administration. ACTA ACUST UNITED AC 2011. [DOI: 10.1097/01.ehx.0000397467.72567.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Li Y, Ting R, Harwig CW, auf dem Keller U, Bellac CL, Lange PF, Inkster JAH, Schaffer P, Adam MJ, Ruth TJ, Overall CM, Perrin DM. Towards kit-like 18F-labeling of marimastat, a noncovalent inhibitor drug for in vivo PET imaging cancer associated matrix metalloproteases. MEDCHEMCOMM 2011. [DOI: 10.1039/c1md00117e] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Biological applications of protein splicing. Cell 2010; 143:191-200. [PMID: 20946979 DOI: 10.1016/j.cell.2010.09.031] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 09/03/2010] [Accepted: 09/14/2010] [Indexed: 11/24/2022]
Abstract
Protein splicing is a naturally occurring process in which a protein editor, called an intein, performs a molecular disappearing act by cutting itself out of a host protein in a traceless manner. In the two decades since its discovery, protein splicing has been harnessed for the development of several protein-engineering methods. Collectively, these technologies help bridge the fields of chemistry and biology, allowing hitherto impossible manipulations of protein covalent structure. These tools and their application are the subject of this Primer.
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A sensitive period for environmental regulation of eating behavior and leptin sensitivity. Proc Natl Acad Sci U S A 2010; 107:16673-8. [PMID: 20823242 DOI: 10.1073/pnas.0911832107] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Western lifestyle contributes to body weight dysregulation. Leptin down-regulates food intake by modulating the activity of neural circuits in the hypothalamic arcuate nucleus (ARC), and resistance to this hormone constitutes a permissive condition for obesity. Physical exercise modulates leptin sensitivity in diet-induced obese rats. The role of other lifestyle components in modulating leptin sensitivity remains elusive. Environmentally enriched mice were used to explore the effects of lifestyle change on leptin production/action and other metabolic parameters. We analyzed adult mice exposed to environmental enrichment (EE), which showed decreased leptin, reduced adipose mass, and increased food intake. We also analyzed 50-d-old mice exposed to either EE (YEE) or physical exercise (YW) since birth, both of which showed decreased leptin. YEE mice showed no change in food intake, increased response to leptin administration, increased activation of STAT3 in the ARC. The YW leptin-induced food intake response was intermediate between young mice kept in standard conditions and YEE. YEE exhibited increased and decreased ratios of excitatory/inhibitory synapses onto α-melanocyte-stimulating hormone and agouti-related peptide neurons of the ARC, respectively. We also analyzed animals as described for YEE and then placed in standard cages for 1 mo. They showed no altered leptin production/action but demonstrated changes in excitatory/inhibitory synaptic contacts in the ARC similar to YEE. EE and physical activity resulted in improved insulin sensitivity. In conclusion, EE and physical activity had an impact on feeding behavior, leptin production/action, and insulin sensitivity, and EE affected ARC circuitry. The leptin-hypothalamic axis is maximally enhanced if environmental stimulation is applied during development.
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Santini F, Galli G, Maffei M, Fierabracci P, Pelosini C, Marsili A, Giannetti M, Castagna MG, Checchi S, Molinaro E, Piaggi P, Pacini F, Elisei R, Vitti P, Pinchera A. Acute exogenous TSH administration stimulates leptin secretion in vivo. Eur J Endocrinol 2010; 163:63-7. [PMID: 20392823 DOI: 10.1530/eje-10-0138] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
TSH-receptor (TSHR) has been found in a variety of cell types, including preadipocytes and adipocytes. In vitro, TSH-mediated preadipocyte and adipocyte responses include proliferation, differentiation, survival, and lipolysis. Objective To measure the response of serum leptin to exogenous administration of recombinant human TSH (rhTSH) in vivo. Patients One hundred patients with differentiated thyroid cancer already treated by total thyroidectomy and (131)I remnant ablation were enrolled. Mean (+/-s.e.m.) body mass index (BMI) was 26.9+/-0.6 kg/m(2). Methods Patients received a standard dose of rhTSH for measurement of thyroglobulin in the follow-up of their disease. Blood samples were taken for the assay of TSH and leptin before the first administration of rhTSH (time 0), and 24 h (time 1), 48 h (time 2), 72 h (time 3), and 96 h (time 4) after the first administration of rhTSH. Results Significant mean serum leptin increments, with respect to basal value, were 16, 13, 18, and 11% at times 1, 2, 3, and 4 respectively. Significant positive correlations of leptin-area under the curve with respect to basal leptin levels (r=0.43; P<0.0001) and BMI (r=0.32; P<0.005) were observed. Conclusions Acute rhTSH administration in hypothyroid subjects under l-thyroxine therapy produces a rise in serum leptin. This increase is proportional to the adipose mass suggesting that a functioning TSHR is expressed on the surface of adipocytes. The role that TSHR activation in adipocytes might play in physiological and pathological conditions remains a matter of investigation.
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Affiliation(s)
- Ferruccio Santini
- Department of Endocrinology and Kidney Dulbecco Telethon Institute at Department of Endocrinology and Kidney University Hospital of Pisa, Via Paradisa, 2, 56124 Pisa, Italy.
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Yamamoto T, Qureshi AR, Anderstam B, Heimbürger O, Bárány P, Lindholm B, Stenvinkel P, Axelsson J. Clinical importance of an elevated circulating chemerin level in incident dialysis patients. Nephrol Dial Transplant 2010; 25:4017-23. [PMID: 20543210 DOI: 10.1093/ndt/gfq329] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Circulating chemerin, a novel adipokine linked to obesity, glucose tolerance and hyperlipidaemia, was recently reported to be increased in chronic kidney disease (CKD) patients. We explored possible links between chemerin and various clinical, nutritional and biochemical markers as well as its association with 5-year all-cause mortality. METHODS Fasting plasma samples were obtained from 252 CKD Stage 5 patients [median age 56 years, male 61%, glomerular filtration rate (GFR) 7 mL/min] enrolled at the initiation of dialysis. Serum chemerin was measured using commercial ELISA. Chemerin levels were related to clinical status and biomarkers of inflammation, glucose and lipid metabolism and body composition (body mass index and total and truncal fat mass by dual-energy X-ray absorptiometry). Survival, censored for transplantation, was recorded for a follow-up time of 5 years. RESULTS In univariate regression, circulating chemerin (119 ± 26 ng/mL) was positively correlated with cholesterol (ρ = 0.21; P = 0.001), triglycerides (ρ = 0.22; P = 0.0007), apolipoprotein B (ρ = 0.33; P < 0.0001), high-sensitivity C-reactive protein (ρ = 0.18; P = 0.006), white blood cell count (ρ = 0.23; P < 0.001), insulin (ρ = 0.18; P < 0.05) and homeostatic model assessment (HOMA) index (ρ = 0.17; P < 0.05), whereas we found a negative correlation with GFR (ρ = -0.28; P = 0.007), high-density lipoprotein cholesterol (ρ = -0.15; P < 0.05) and homocysteine (ρ = -0.25; P = 0.001). Moreover, a high chemerin predicted a better survival (log-rank χ(2) = 3.85; P < 0.05). Also, in a Cox model, adjustments for age, sex and CRP did not alter this finding (hazard ratio = 1.98 [95% confidence interval = 1.13-3.50], P = 0.01). However, adjusting for GFR made the model non-significant. CONCLUSIONS We report that, in incident dialysis patients, an elevated chemerin is associated with a survival advantage despite its significant positive association with markers of inflammation and dyslipidaemia.
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Affiliation(s)
- Tae Yamamoto
- Renal Medicine and Baxter Novum, Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
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