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Possa-Paranhos IC, Butts J, Pyszka E, Nelson C, Cho D, Sweeney P. Neuroanatomical dissection of the MC3R circuitry regulating energy rheostasis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590573. [PMID: 38712101 PMCID: PMC11071362 DOI: 10.1101/2024.04.22.590573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Although mammals resist both acute weight loss and weight gain, the neural circuitry mediating bi-directional defense against weight change is incompletely understood. Global constitutive deletion of the melanocortin-3-receptor (MC3R) impairs the behavioral response to both anorexic and orexigenic stimuli, with MC3R knockout mice demonstrating increased weight gain following anabolic challenges and increased weight loss following anorexic challenges (i.e. impaired energy rheostasis). However, the brain regions mediating this phenotype remain incompletely understood. Here, we utilized MC3R floxed mice and viral injections of Cre-recombinase to selectively delete MC3R from medial hypothalamus (MH) in adult mice. Behavioral assays were performed on these animals to test the role of MC3R in MH in the acute response to orexigenic and anorexic challenges. Complementary chemogenetic approaches were used in MC3R-Cre mice to localize and characterize the specific medial hypothalamic brain regions mediating the role of MC3R in energy homeostasis. Finally, we performed RNAscope in situ hybridization to map changes in the mRNA expression of MC3R, POMC, and AgRP following energy rheostatic challenges. Our results demonstrate that MC3R deletion in MH increased feeding and weight gain following acute high fat diet feeding in males, and enhanced the anorexic effects of semaglutide, in a sexually dimorphic manner. Additionally, activation of DMH MC3R neurons increased energy expenditure and locomotion. Together, these results demonstrate that MC3R mediated effects on energy rheostasis result from the loss of MC3R signaling in the medial hypothalamus of adult animals and suggest an important role for DMH MC3R signaling in energy rheostasis. Key Points: MC3R signaling regulates energy rheostasis in adult miceMedial hypothalamus regulates energy rheostasis in adult miceEnergy rheostasis alters mRNA levels of AgRP and MC3R in DMHDMH MC3R neurons increase locomotion and energy expenditureMC3R expression in DMH is sexually dimorphic.
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Ong SG, Dehghan R, Dorajoo R, Liu JJ, Sng AA, Lee YS, Ooi DSQ. Novel Melanocortin-3 and -4 Receptor Functional Variants in Asian Children With Severe Obesity. J Clin Endocrinol Metab 2024; 109:e1249-e1259. [PMID: 37820740 DOI: 10.1210/clinem/dgad602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 10/06/2023] [Accepted: 10/09/2023] [Indexed: 10/13/2023]
Abstract
CONTEXT Genetic variants in melanocortin 3 receptor (MC3R) and melanocortin 4 receptor (MC4R) genes are strongly associated with childhood obesity. OBJECTIVE This study aims to identify and functionally characterize MC3R and MC4R variants in an Asian cohort of children with severe early-onset obesity. METHODS Whole-exome sequencing was performed to screen for MC3R and MC4R coding variants in 488 Asian children with severe early-onset obesity (body mass index for age ≥97th percentile). Functionality of the identified variants were determined via measurement of intracellular cyclic adenosine monophosphate (cAMP) concentrations and luciferase activity. RESULTS Four MC3R and 2 MC4R heterozygous nonsynonymous rare variants were detected. There were 3 novel variants: MC3R c.151G > C (p.Val51Leu), MC4R c.127C > A (p.Gln43Lys), and MC4R c.272T > G (p.Met91Arg), and 3 previously reported variants: MC3R c.127G > A (p.Glu43Lys), MC3R c.97G > A (p.Ala33Thr), and MC3R c.437T > A (p.Ile146Asn). Both MC3R c.127G > A (p.Glu43Lys) and MC4R c.272T > G (p.Met91Arg) variants demonstrated defective downstream cAMP signaling activity. The MC4R c.127C > A (p.Gln43Lys) variant showed reduced cAMP signaling activity at low substrate concentration but the signaling activity was restored at high substrate concentration. The MC3R c.151G > C (p.Val51Leu) variant did not show a significant reduction in cAMP signaling activity compared to wild-type (WT) MC3R. Coexpression studies of the WT and variant MC3R/MC4R showed that the heterozygous variants did not exhibit dominant negative effect. CONCLUSION Our functional assays demonstrated that MC3R c.127G > A (p.Glu43Lys) and MC4R c.272T > G (p.Met91Arg) variants might predispose individuals to early-onset obesity, and further studies are needed to establish the causative effect of these variants in the pathogenesis of obesity.
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Affiliation(s)
- Siong Gim Ong
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Division of Paediatric Endocrinology, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore 119228, Singapore
| | - Roghayeh Dehghan
- Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore 138672, Singapore
- Department of Genetics and Molecular Biology, School of Medicine, University of Medical Science, Isfahan 81746-73461, Iran
| | - Rajkumar Dorajoo
- Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore 138672, Singapore
| | - Jian-Jun Liu
- Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore 138672, Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Andrew Anjian Sng
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Division of Paediatric Endocrinology, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore 119228, Singapore
| | - Yung Seng Lee
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Division of Paediatric Endocrinology, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore 119228, Singapore
| | - Delicia Shu Qin Ooi
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Division of Paediatric Endocrinology, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore 119228, Singapore
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Bedenbaugh MN, Brener SC, Maldonado J, Lippert RN, Sweeney P, Cone RD, Simerly RB. Organization of neural systems expressing melanocortin-3 receptors in the mouse brain: Evidence for sexual dimorphism. J Comp Neurol 2022; 530:2835-2851. [PMID: 35770983 PMCID: PMC9724692 DOI: 10.1002/cne.25379] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/24/2022] [Accepted: 05/27/2022] [Indexed: 01/13/2023]
Abstract
The central melanocortin system is fundamentally important for controlling food intake and energy homeostasis. Melanocortin-3 receptor (MC3R) is one of two major receptors of the melanocortin system found in the brain. In contrast to the well-characterized melanocortin-4 receptor (MC4R), little is known regarding the organization of MC3R-expressing neural circuits. To increase our understanding of the intrinsic organization of MC3R neural circuits, identify specific differences between males and females, and gain a neural systems level perspective of this circuitry, we conducted a brain-wide mapping of neurons labeled for MC3R and characterized the distribution of their projections. Analysis revealed MC3R neuronal and terminal labeling in multiple brain regions that control a diverse range of physiological functions and behavioral processes. Notably, dense labeling was observed in the hypothalamus, as well as areas that share considerable connections with the hypothalamus, including the cortex, amygdala, thalamus, and brainstem. Additionally, MC3R neuronal labeling was sexually dimorphic in several areas, including the anteroventral periventricular area, arcuate nucleus, principal nucleus of the bed nucleus of the stria terminalis, and ventral premammillary region. Altogether, anatomical evidence reported here suggests that MC3R has the potential to influence several different classes of motivated behavior that are essential for survival, including ingestive, reproductive, defensive, and arousal behaviors, and is likely to modulate these behaviors differently in males and females.
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Affiliation(s)
- Michelle N. Bedenbaugh
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Samantha C. Brener
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Jose Maldonado
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Rachel N. Lippert
- Department of Neurocircuit Development and Function, German Institute of Human Nutrition Potsdam-Rehbruecke, Potsdam, Germany
| | - Patrick Sweeney
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
- Department of Molecular and Integrative Physiology, School of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Roger D. Cone
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
- Department of Molecular and Integrative Physiology, School of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Richard B. Simerly
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA
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Venkatesh K, Mishra C, Pradhan SK. Integrative molecular characterization and in silico analyses of caprine MC3R, MC4R, and MC5R genes. Small Rumin Res 2022. [DOI: 10.1016/j.smallrumres.2022.106812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Piper NBC, Whitfield EA, Stewart GD, Xu X, Furness SGB. Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors. Biochem Pharmacol 2022; 202:115115. [PMID: 35671790 DOI: 10.1016/j.bcp.2022.115115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.
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Affiliation(s)
- Noah B C Piper
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Emily A Whitfield
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Gregory D Stewart
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Xiaomeng Xu
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Sebastian G B Furness
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia; Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia.
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Stevenson TJ, Liddle TA, Stewart C, Marshall CJ, Majumdar G. Neural programming of seasonal physiology in birds and mammals: A modular perspective. Horm Behav 2022; 142:105153. [PMID: 35325691 DOI: 10.1016/j.yhbeh.2022.105153] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/30/2022] [Accepted: 03/07/2022] [Indexed: 11/17/2022]
Abstract
Most animals in the temperate zone exhibit robust seasonal rhythms in neuroendocrine, physiological and behavioral processes. The integration of predictive and supplementary environmental cues (e.g., nutrients) involves a series of discrete, and interconnected brain regions that span hypothalamic, thalamic, mesencephalic, and limbic regions. Species-specific adaptive changes in these neuroendocrine structures and cellular plasticity have likely evolved to support seasonal life-history transitions. Despite significant advances in our understanding of ecological responses to predictive and supplementary environmental cues, there remains a paucity of literature on how these diverse cues impact the underlying neural and cellular substrates. To date, most scientific approach has focused on neuroendocrine responses to annual changes in daylength, referred to as photoperiod, due to the robust physiological changes to light manipulations in laboratory settings. In this review, we highlight the relatively few animal models that have been effectively used to investigate how predictive day lengths, and supplementary cues are integrated across hypothalamic nuclei, and discuss key findings of how seasonal rhythms in physiology are governed by adaptive neuroendocrine changes. We discuss how specific brain regions integrate environmental cues to form a complex multiunit or 'modular' system that has evolved to optimize the timing of seasonal physiology. Overall, the review aims to highlight the existence of a modular network of neural regions that independently contribute to timing seasonal physiology. This paper proposes that a multi-modular neuroendocrine system has evolved in which independent neural 'units' operate to support species-specific seasonal rhythms.
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Affiliation(s)
- Tyler J Stevenson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom.
| | - Timothy A Liddle
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
| | - Calum Stewart
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
| | - Christopher J Marshall
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
| | - Gaurav Majumdar
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
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Tu L, Fukuda M, Tong Q, Xu Y. The ventromedial hypothalamic nucleus: watchdog of whole-body glucose homeostasis. Cell Biosci 2022; 12:71. [PMID: 35619170 PMCID: PMC9134642 DOI: 10.1186/s13578-022-00799-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/25/2022] [Indexed: 02/06/2023] Open
Abstract
The brain, particularly the ventromedial hypothalamic nucleus (VMH), has been long known for its involvement in glucose sensing and whole-body glucose homeostasis. However, it is still not fully understood how the brain detects and responds to the changes in the circulating glucose levels, as well as brain-body coordinated control of glucose homeostasis. In this review, we address the growing evidence implicating the brain in glucose homeostasis, especially in the contexts of hypoglycemia and diabetes. In addition to neurons, we emphasize the potential roles played by non-neuronal cells, as well as extracellular matrix in the hypothalamus in whole-body glucose homeostasis. Further, we review the ionic mechanisms by which glucose-sensing neurons sense fluctuations of ambient glucose levels. We also introduce the significant implications of heterogeneous neurons in the VMH upon glucose sensing and whole-body glucose homeostasis, in which sex difference is also addressed. Meanwhile, research gaps have also been identified, which necessities further mechanistic studies in future.
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Affiliation(s)
- Longlong Tu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street #8066, Houston, TX, 77030, USA
| | - Makoto Fukuda
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street #8066, Houston, TX, 77030, USA
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Yong Xu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street #8066, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
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Akat E, Yenmiş M, Pombal MA, Molist P, Megías M, Arman S, Veselỳ M, Anderson R, Ayaz D. Comparison of Vertebrate Skin Structure at Class Level: A Review. Anat Rec (Hoboken) 2022; 305:3543-3608. [DOI: 10.1002/ar.24908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 02/14/2022] [Accepted: 02/21/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Esra Akat
- Ege University, Faculty of Science, Biology Department Bornova, İzmir Turkey
| | - Melodi Yenmiş
- Ege University, Faculty of Science, Biology Department Bornova, İzmir Turkey
| | - Manuel A. Pombal
- Universidade de Vigo, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía‐IBIV Vigo, España
| | - Pilar Molist
- Universidade de Vigo, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía‐IBIV Vigo, España
| | - Manuel Megías
- Universidade de Vigo, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía‐IBIV Vigo, España
| | - Sezgi Arman
- Sakarya University, Faculty of Science and Letters, Biology Department Sakarya Turkey
| | - Milan Veselỳ
- Palacky University, Faculty of Science, Department of Zoology Olomouc Czechia
| | - Rodolfo Anderson
- Departamento de Zoologia, Instituto de Biociências Universidade Estadual Paulista São Paulo Brazil
| | - Dinçer Ayaz
- Ege University, Faculty of Science, Biology Department Bornova, İzmir Turkey
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Melanocortin 3 receptor-expressing neurons in the ventromedial hypothalamus promote glucose disposal. Proc Natl Acad Sci U S A 2021; 118:2103090118. [PMID: 33827930 PMCID: PMC8053962 DOI: 10.1073/pnas.2103090118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ventromedial hypothalamus (VMH) is a critical neural node that senses blood glucose and promotes glucose utilization or mobilization during hypoglycemia. The VMH neurons that control these distinct physiologic processes are largely unknown. Here, we show that melanocortin 3 receptor (Mc3R)-expressing VMH neurons (VMHMC3R) sense glucose changes both directly and indirectly via altered excitatory input. We identify presynaptic nodes that potentially regulate VMHMC3R neuronal activity, including inputs from proopiomelanocortin (POMC)-producing neurons in the arcuate nucleus. We find that VMHMC3R neuron activation blunts, and their silencing enhances glucose excursion following a glucose load. Overall, these findings demonstrate that VMHMC3R neurons are a glucose-responsive hypothalamic subpopulation that promotes glucose disposal upon activation; this highlights a potential site for targeting dysregulated glycemia.
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10
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Immunoglobulin G modulation of the melanocortin 4 receptor signaling in obesity and eating disorders. Transl Psychiatry 2019; 9:87. [PMID: 30755592 PMCID: PMC6372612 DOI: 10.1038/s41398-019-0422-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 12/10/2018] [Accepted: 01/02/2019] [Indexed: 12/23/2022] Open
Abstract
Melanocortin 4 receptor (MC4R) plays a key role in regulation of appetite activated by its main ligand α-melanocyte-stimulating hormone (α-MSH) in both central and peripheral targets. α-MSH also binds to circulating immunoglobulins (Igs) but the functional significance of such immune complexes (ICs) in MC4R signaling in normal and pathological conditions of altered appetite has remained unknown. To address this question, we analyzed plasma levels, affinity kinetics, and binding epitopes of α-MSH-reactive IgG extracted from plasma samples of female patients with hyperphagic obesity, anorexia nervosa, bulimia nervosa, binge-eating disorder, and healthy controls. Ability of α-MSH/IgG IC to bind and activate human MC4R were studied in vitro and to influence feeding behavior in vivo in rodents. We found that α-MSH-reactive IgG were low in obese but increased in anorectic and bulimic patients and displayed different epitope and kinetics of IC formation. Importantly, while α-MSH/IgG IC from all subjects were binding and activating MC4R, the receptor binding affinity was decreased in obesity. Additionally, α-MSH/IgG IC had lower MC4R-mediated cAMP activation threshold as compared with α-MSH alone in all but not obese subjects. Furthermore, the cellular internalization rate of α-MSH/IgG IC by MC4R-expressing cells was decreased in obese but increased in patients with anorexia nervosa. Moreover, IgG from obese patients prevented central anorexigenic effect of α-MSH. These findings reveal that MC4R is physiologically activated by IC formed by α-MSH/IgG and that different levels and molecular properties of α-MSH-reactive IgG underlie biological activity of such IC relevant to altered appetite in obesity and eating disorders.
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11
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Pei H, Patterson CM, Sutton AK, Burnett KH, Myers MG, Olson DP. Lateral Hypothalamic Mc3R-Expressing Neurons Modulate Locomotor Activity, Energy Expenditure, and Adiposity in Male Mice. Endocrinology 2019; 160:343-358. [PMID: 30541071 PMCID: PMC6937456 DOI: 10.1210/en.2018-00747] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 12/04/2018] [Indexed: 02/05/2023]
Abstract
The central melanocortin system plays a crucial role in the control of energy balance. Although the decreased energy expenditure and increased adiposity of melanocortin-3 receptor (Mc3R)-null mice suggest the importance of Mc3R-regulated neurons in energy homeostasis, the roles for specific subsets of Mc3R neurons in energy balance have yet to be determined. Because the lateral hypothalamic area (LHA) contributes to the control of energy expenditure and feeding, we generated Mc3rcre mice to determine the roles of LHA Mc3R (Mc3RLHA) neurons in energy homeostasis. We found that Mc3RLHA neurons overlap extensively with LHA neuron markers that contribute to the control of energy balance (neurotensin, galanin, and leptin receptor) and project to brain areas involved in the control of feeding, locomotion, and energy expenditure, consistent with potential roles for Mc3RLHA neurons in these processes. Indeed, selective chemogenetic activation of Mc3RLHA neurons increased locomotor activity and augmented refeeding after a fast. Although the ablation of Mc3RLHA neurons did not alter food intake, mice lacking Mc3RLHA neurons displayed decreased energy expenditure and locomotor activity, along with increased body mass and adiposity. Thus, Mc3R neurons lie within LHA neurocircuitry that modulates locomotor activity and energy expenditure and contribute to energy balance control.
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Affiliation(s)
- Hongjuan Pei
- Division of Endocrinology, Department of Pediatrics, Michigan Medicine, Ann Arbor, Michigan
| | | | - Amy K Sutton
- Molecular and Integrative Physiology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan
| | - Korri H Burnett
- Division of Endocrinology, Department of Pediatrics, Michigan Medicine, Ann Arbor, Michigan
| | - Martin G Myers
- Department of Internal Medicine, Michigan Medicine, Ann Arbor, Michigan
- Molecular and Integrative Physiology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan
| | - David P Olson
- Division of Endocrinology, Department of Pediatrics, Michigan Medicine, Ann Arbor, Michigan
- Molecular and Integrative Physiology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan
- Correspondence: David P. Olson, MD, PhD, University of Michigan, 1000 Wall Street, Brehm Tower 6329, Ann Arbor, Michigan 48105. E-mail:
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12
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Girardet C, Marks DL, Butler AA. Melanocortin-3 Receptors Expressed on Agouti-Related Peptide Neurons Inhibit Feeding Behavior in Female Mice. Obesity (Silver Spring) 2018; 26:1849-1855. [PMID: 30426710 PMCID: PMC7294842 DOI: 10.1002/oby.22306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/27/2018] [Accepted: 07/30/2018] [Indexed: 12/29/2022]
Abstract
OBJECTIVE Activation of hypothalamic agouti-related peptide expressing (AgRP)+ve neurons during energy deficit is a negative valence signal, rapidly activating food-seeking behaviors. This study examined the roles of melanocortin-3 receptors (MC3Rs) coexpressed in a subpopulation of AgRP+ve neurons. METHODS AgRP-MC3R mice expressing MC3Rs selectively in AgRP+ve neurons were generated by crossing AgRP-IRES-Cre mice with LoxTBMc3r mice containing a "loxP-STOP-loxP" sequence in the 5' untranslated region. Body weight, body composition, and feeding behavior were assessed during ad libitum and time-restricted feeding conditions. RESULTS In females, food intake of AgRP-IRES-Cre+ve (n = 7) or AgRP-IRES-Cre-ve (n = 9) mice was not significantly different; these mice were therefore pooled to form the "control" group. Female AgRP-MC3R mice exhibited lower food intake (25.4 ± 2.4 kJ/12 h; n = 6) compared with controls (35.3 ± 1.8 kJ/12 h; n = 16) and LoxTBMc3r mice (32.1 ± 2.1 kJ/12 h; n = 9) in the active phase during the dark period. Food intake during the rest phase (lights on) when mice consume less food (9-10 kJ) was normal between genotypes. Body weight and composition of AgRP-MC3R and LoxTBMc3r mice were similar, suggesting compensatory mechanisms for reduced calorie intake. Remarkably, AgRP-MC3R mice continued to consume less food during refeeding after fasting and time-restricted feeding. CONCLUSIONS MC3Rs expressed on AgRP+ve neurons appear to exert a strong inhibitory signal on hypothalamic networks governing feeding behavior.
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Affiliation(s)
- Clemence Girardet
- Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Daniel L. Marks
- Department of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Mail Code L481 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
| | - Andrew A. Butler
- Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
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Eerola K, Virtanen S, Vähätalo L, Ailanen L, Cai M, Hruby V, Savontaus M, Savontaus E. Hypothalamic γ-melanocyte stimulating hormone gene delivery reduces fat mass in male mice. J Endocrinol 2018; 239:19–31. [PMID: 30307151 DOI: 10.1530/joe-18-0009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
γ-Melanocyte stimulating hormone (γ-MSH) is an endogenous agonist of the melanocortin 3-receptor (MC3R). Genetic disruption of MC3Rs increases adiposity and blunts responses to fasting, suggesting that increased MC3R signaling could be physiologically beneficial in the long term. Interestingly, several studies have concluded that activation of MC3Rs is orexigenic in the short term. Therefore, we aimed to examine the short- and long-term effects of γ-MSH in the hypothalamic arcuate nucleus (ARC) on energy homeostasis and hypothesized that the effect of MC3R agonism is dependent on the state of energy balance and nutrition. Lentiviral gene delivery was used to induce a continuous expression of γ-Msh only in the ARC of male C57Bl/6N mice. Parameters of body energy homeostasis were monitored as food was changed from chow (6 weeks) to Western diet (13 weeks) and back to chow (7 weeks). The γ-MSH treatment decreased the fat mass to lean mass ratio on chow, but the effect was attenuated on Western diet. After the switch back to chow, an enhanced loss in weight (−15% vs −6%) and fat mass (−37% vs −12%) and reduced cumulative food intake were observed in γ-MSH-treated animals. Fasting-induced feeding was increased on chow diet only; however, voluntary running wheel activity on Western diet was increased. The γ-MSH treatment also modulated the expression of key neuropeptides in the ARC favoring weight loss. We have shown that a chronic treatment intended to target ARC MC3Rs modulates energy balance in nutritional state-dependent manner. Enhancement of diet-induced weight loss could be beneficial in treatment of obesity.
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Affiliation(s)
- K Eerola
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
| | - S Virtanen
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - L Vähätalo
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - L Ailanen
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Drug Research Doctoral Program, University of Turku, Turku, Finland
| | - M Cai
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - V Hruby
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - M Savontaus
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
- Heart Center, Turku University Hospital and University of Turku, Turku, Finland
| | - E Savontaus
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
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14
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Phifer-Rixey M, Bi K, Ferris KG, Sheehan MJ, Lin D, Mack KL, Keeble SM, Suzuki TA, Good JM, Nachman MW. The genomic basis of environmental adaptation in house mice. PLoS Genet 2018; 14:e1007672. [PMID: 30248095 PMCID: PMC6171964 DOI: 10.1371/journal.pgen.1007672] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 10/04/2018] [Accepted: 08/30/2018] [Indexed: 01/18/2023] Open
Abstract
House mice (Mus musculus) arrived in the Americas only recently in association with European colonization (~400-600 generations), but have spread rapidly and show evidence of local adaptation. Here, we take advantage of this genetic model system to investigate the genomic basis of environmental adaptation in house mice. First, we documented clinal patterns of phenotypic variation in 50 wild-caught mice from a latitudinal transect in Eastern North America. Next, we found that progeny of mice from different latitudes, raised in a common laboratory environment, displayed differences in a number of complex traits related to fitness. Consistent with Bergmann's rule, mice from higher latitudes were larger and fatter than mice from lower latitudes. They also built bigger nests and differed in aspects of blood chemistry related to metabolism. Then, combining exomic, genomic, and transcriptomic data, we identified specific candidate genes underlying adaptive variation. In particular, we defined a short list of genes with cis-eQTL that were identified as candidates in exomic and genomic analyses, all of which have known ties to phenotypes that vary among the studied populations. Thus, wild mice and the newly developed strains represent a valuable resource for future study of the links between genetic variation, phenotypic variation, and climate.
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Affiliation(s)
- Megan Phifer-Rixey
- Department of Biology, Monmouth University, West Long Branch, New Jersey, United States of America
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
| | - Ke Bi
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
- Computational Genomics Resource Laboratory, California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, California, United States of America
| | - Kathleen G. Ferris
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
| | - Michael J. Sheehan
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
| | - Dana Lin
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
| | - Katya L. Mack
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
| | - Sara M. Keeble
- Division of Biological Sciences, University of Montana, Missoula, Missoula, Montana, United States of America
- Department of Molecular and Computational Biology, University of Southern California, Los Angeles, Los Angeles, California, United States of America
| | - Taichi A. Suzuki
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
| | - Jeffrey M. Good
- Division of Biological Sciences, University of Montana, Missoula, Missoula, Montana, United States of America
| | - Michael W. Nachman
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, United States of America
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15
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Liang J, Li L, Jin X, Xu B, Pi L, Liu S, Zhu W, Zhang C, Luan B, Gong L, Zhang C. Pharmacological effect of human melanocortin-2 receptor accessory protein 2 variants on hypothalamic melanocortin receptors. Endocrine 2018; 61:94-104. [PMID: 29704154 DOI: 10.1007/s12020-018-1596-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 04/09/2018] [Indexed: 10/17/2022]
Abstract
PURPOSE Melanocortin-3 receptor (MC3R), melanocortin-4 receptor (MC4R), and a recently identified melanocortin-2 receptor accessory protein 2 (MRAP2), are highly expressed in hypothalamus and coordinately regulate energy homeostasis, but the single cellular transcriptome of melanocortin system remains unknown. Several infrequent MRAP2 variants are reported from severe obese human patients but the mechanisms on how they affect melanocortin signaling are unclear. METHODS First, we performed in silico analysis of mouse hypothalamus RNA sequencing datasets at single-cell resolution from two independent studies. Next, we inspected the three-dimensional conformational alteration of three mutations on MRAP2 protein. Finally, the influence of MRAP2 variants on MC3R and MC4R signaling was analyzed in vitro. RESULTS (1) We confirmed the actual co-expression of Mrap2 with Mc3r and Mc4r, and demonstrated more broad distribution of Mrap2-positive neuronal populations than Mc3r or Mc4r in mouse hypothalamus. (2) Compared with wild-type MRAP2, MRAP2N88Y, and MRAP2R125C showed impaired α-MSH-induced MC4R or MC3R stimulation. (3) MRAP2N88Yexhibited enhanced interaction with MC4R protein and its own. CONCLUSIONS This is the first dedicated description of single-cell transcriptome signature of Mrap2, Mc3r, and Mc4r in the central nerve system and the first evidence describing the unique dimer formation, conformational change, and pharmacological effect of MRAP2 mutations on MC3R signaling.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Carrier Proteins/pharmacology
- Computer Simulation
- Genetic Variation
- Humans
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Mice
- Mutation/genetics
- Neurons/metabolism
- Nucleic Acid Conformation
- Plasmids
- RNA/genetics
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Receptors, Melanocortin/drug effects
- Signal Transduction/genetics
- alpha-MSH/pharmacology
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Affiliation(s)
- Jinye Liang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Lei Li
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Xuanxuan Jin
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bingxin Xu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Linyu Pi
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Shangyun Liu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Wei Zhu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Cong Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bing Luan
- Department of Endocrinology, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Lulu Gong
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China.
| | - Chao Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China.
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16
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Manfredi-Lozano M, Roa J, Tena-Sempere M. Connecting metabolism and gonadal function: Novel central neuropeptide pathways involved in the metabolic control of puberty and fertility. Front Neuroendocrinol 2018; 48:37-49. [PMID: 28754629 DOI: 10.1016/j.yfrne.2017.07.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/20/2017] [Accepted: 07/23/2017] [Indexed: 02/08/2023]
Abstract
Albeit essential for perpetuation of species, reproduction is an energy-demanding function that can be adjusted to body metabolic status. Reproductive maturation and function can be suppressed in conditions of energy deficit, but can be altered also in situations of persistent energy excess, e.g., morbid obesity. This metabolic-reproductive integration, of considerable pathophysiological relevance to explain different forms of perturbed puberty and sub/infertility, is implemented by the concerted action of numerous central and peripheral regulators, which impinge at different levels of the hypothalamic-pituitary-gonadal (HPG) axis, permitting a tight fit between nutritional/energy status and gonadal function. We summarize here the major physiological mechanisms whereby nutritional and metabolic cues modulate the maturation and function of the HPG axis. We will focus on recent progress on the major central neuropeptide pathways, including kisspeptins, neurokinin B and the products of POMC and NPY neurons, which convey metabolic information to GnRH neurons, as major hierarchical hub of our reproductive brain.
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Affiliation(s)
- M Manfredi-Lozano
- Instituto Maimónides de Investigación Biomédica de Cordoba (IMIBIC), Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, Spain; Hospital Universitario Reina Sofia, 14004 Cordoba, Spain; Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, INSERM, U1172, Lille, France
| | - J Roa
- Instituto Maimónides de Investigación Biomédica de Cordoba (IMIBIC), Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, Spain; Hospital Universitario Reina Sofia, 14004 Cordoba, Spain.
| | - M Tena-Sempere
- Instituto Maimónides de Investigación Biomédica de Cordoba (IMIBIC), Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, Spain; Hospital Universitario Reina Sofia, 14004 Cordoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Cordoba, Spain; FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.
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17
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Bombesin-like receptor 3 (Brs3) expression in glutamatergic, but not GABAergic, neurons is required for regulation of energy metabolism. Mol Metab 2017; 6:1540-1550. [PMID: 29107299 PMCID: PMC5681273 DOI: 10.1016/j.molmet.2017.08.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 02/03/2023] Open
Abstract
Objective Bombesin-like receptor 3 (BRS-3) is an orphan G protein-coupled receptor. Brs3 null mice have reduced resting metabolic rate and body temperature, increased food intake, and obesity. Here we study the role of Brs3 in different neuron types. Methods Mice able to undergo Cre recombinase-dependent inactivation or re-expression of Brs3 were generated, respectively Brs3fl/y and Brs3loxTB/y. We then studied four groups of mice with Brs3 selectively inactivated or re-expressed in cells expressing Vglut2-Cre or Vgat-Cre. Results Deletion of Brs3 in glutamatergic neurons expressing Vglut2 reproduced the global null phenotype for regulation of food intake, metabolic rate, body temperature, adiposity, and insulin resistance. These mice also no longer responded to a BRS-3 agonist, MK-5046. In contrast, deletion of Brs3 in GABAergic neurons produced no detectable phenotype. Conversely, the wild type phenotype was restored by selective re-expression of Brs3 in glutamatergic neurons, with no normalization achieved by re-expressing Brs3 in GABAergic neurons. Conclusions Brs3 expression in glutamatergic neurons is both necessary and sufficient for full Brs3 function in energy metabolism. In these experiments, no function was identified for Brs3 in GABAergic neurons. The data suggest that the anti-obesity pharmacologic actions of BRS-3 agonists occur via agonism of receptors on glutamatergic neurons. Brs3 in glutamatergic neurons regulates food intake, metabolic rate, and body weight. Brs3 in glutamatergic neurons is both necessary and sufficient for these functions. No phenotypes were identified by Brs3 loss or re-expression in GABAergic neurons. BRS-3 agonists likely act on glutamatergic neurons for their anti-obesity effects.
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18
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Demidowich AP, Jun JY, Yanovski JA. Polymorphisms and mutations in the melanocortin-3 receptor and their relation to human obesity. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2468-2476. [PMID: 28363697 DOI: 10.1016/j.bbadis.2017.03.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 12/18/2022]
Abstract
Inactivating mutations in the melanocortin 3 receptor (Mc3r) have been described as causing obesity in mice, but the physiologic effects of MC3R mutations in humans have been less clear. Here we review the MC3R polymorphisms and mutations identified in humans, and the in vitro, murine, and human cohort studies examining their putative effects. Some, but not all, studies suggest that the common human MC3R variant T6K+V81I, as well as several other rare, function-altering mutations, are associated with greater adiposity and hyperleptinemia with altered energy partitioning. In vitro, the T6K+V81I variant appears to decrease MC3R expression and therefore cAMP generation in response to ligand binding. Knockin mouse studies confirm that the T6K+V81I variant increases feeding efficiency and the avidity with which adipocytes derived from bone or adipose tissue stem cells store triglycerides. Other MC3R mutations occur too infrequently in the human population to make definitive conclusions regarding their clinical effects. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.
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Affiliation(s)
- Andrew P Demidowich
- Section on Growth and Obesity, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Joo Yun Jun
- Section on Growth and Obesity, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Jack A Yanovski
- Section on Growth and Obesity, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States.
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19
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Butler AA, Girardet C, Mavrikaki M, Trevaskis JL, Macarthur H, Marks DL, Farr SA. A Life without Hunger: The Ups (and Downs) to Modulating Melanocortin-3 Receptor Signaling. Front Neurosci 2017; 11:128. [PMID: 28360832 PMCID: PMC5352694 DOI: 10.3389/fnins.2017.00128] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/01/2017] [Indexed: 11/13/2022] Open
Abstract
Melanocortin neurons conserve body mass in hyper- or hypo-caloric conditions by conveying signals from nutrient sensors into areas of the brain governing appetite and metabolism. In mice, melanocortin-3 receptor (MC3R) deletion alters nutrient partitioning independently of hyperphagia, promoting accumulation of fat over muscle mass. Enhanced rhythms in insulin and insulin-responsive metabolic genes during hypocaloric feeding suggest partial insulin resistance and enhanced lipogenesis. However, exactly where and how MC3Rs affect metabolic control to alter nutrient partitioning is not known. The behavioral phenotypes exhibited by MC3R-deficient mice suggest a contextual role in appetite control. The impact of MC3R-deficiency on feeding behavior when food is freely available is minor. However, homeostatic responses to hypocaloric conditioning involving increased expression of appetite-stimulating (orexigenic) neuropeptides, binge-feeding, food anticipatory activity (FAA), entrainment to nutrient availability and enhanced feeding-related motivational responses are compromised with MC3R-deficiency. Rescuing Mc3r transcription in hypothalamic and limbic neurons improves appetitive responses during hypocaloric conditioning while having minor effects on nutrient partitioning, suggesting orexigenic functions. Rescuing hypothalamic MC3Rs also restores responses of fasting-responsive hypothalamic orexigenic neurons in hypocaloric conditions, suggesting actions that sensitize fasting-responsive neurons to signals from nutrient sensors. MC3R signaling in ventromedial hypothalamic SF1(+ve) neurons improves metabolic control, but does not restore appetitive responses or nutrient partitioning. In summary, desensitization of fasting-responsive orexigenic neurons may underlie attenuated appetitive responses of MC3R-deficient mice in hypocaloric situations. Further studies are needed to identify the specific location(s) of MC3Rs controlling appetitive responses and partitioning of nutrients between fat and lean tissues.
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Affiliation(s)
- Andrew A Butler
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine St. Louis, MO, USA
| | - Clemence Girardet
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine St. Louis, MO, USA
| | - Maria Mavrikaki
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine St. Louis, MO, USA
| | - James L Trevaskis
- In vivo Pharmacology, Cardiovascular and Metabolic Disease, Medimmune Gaithersburg, MD, USA
| | - Heather Macarthur
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine St. Louis, MO, USA
| | - Daniel L Marks
- Papé Family Pediatric Research Institute, Oregon Health and Science University Portland, OR, USA
| | - Susan A Farr
- Department of Internal Medicine, Division of Geriatrics, Saint Louis University School of MedicineSt. Louis, MO, USA; VA Medical CenterSt. Louis, MO, USA
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20
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Melanocortin-3 receptors expressed in Nkx2.1(+ve) neurons are sufficient for controlling appetitive responses to hypocaloric conditioning. Sci Rep 2017; 7:44444. [PMID: 28294152 PMCID: PMC5353610 DOI: 10.1038/srep44444] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 02/08/2017] [Indexed: 01/12/2023] Open
Abstract
Melanocortin-3 receptors (MC3R) have a contextual role in appetite control that is amplified with hypocaloric conditioning. C57BL/6J (B6) mice subjected to hypocaloric feeding schedules (HFS) exhibit compulsive behavioral responses involving food anticipatory activity (FAA) and caloric loading following food access. These homeostatic responses to calorie-poor environs are attenuated in B6 mice in which Mc3r transcription is suppressed by a lox-stop-lox sequence in the 5'UTR (Mc3rTB/TB). Here, we report that optimization of caloric loading in B6 mice subject to HFS, characterized by increased meal size and duration, is not observed in Mc3rTB/TB mice. Analysis of hypothalamic and neuroendocrine responses to HFS throughout the light-dark cycle suggests uncoupling of hypothalamic responses involving appetite-stimulating fasting-responsive hypothalamic neurons expressing agouti-related peptide (AgRP) and neuropeptide Y (Npy). Rescuing Mc3rs expression in Nkx2.1(+ve) neurons is sufficient to restore normal hypothalamic responses to negative energy balance. In addition, Mc3rs expressed in Nkx2.1(+ve) neurons are also sufficient to restore FAA and caloric loading of B6 mice subjected to HFS. In summary, MC3Rs expressed in Nkx2.1(+ve) neurons are sufficient to coordinate hypothalamic response and expression of compulsive behavioral responses involving meal anticipation and consumption of large meals during situations of prolonged negative energy balance.
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21
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Singh RK, Kumar P, Mahalingam K. Molecular genetics of human obesity: A comprehensive review. C R Biol 2017; 340:87-108. [PMID: 28089486 DOI: 10.1016/j.crvi.2016.11.007] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 10/03/2016] [Accepted: 11/10/2016] [Indexed: 12/25/2022]
Abstract
Obesity and its related health complications is a major problem worldwide. Hypothalamus and their signalling molecules play a critical role in the intervening and coordination with energy balance and homeostasis. Genetic factors play a crucial role in determining an individual's predisposition to the weight gain and being obese. In the past few years, several genetic variants were identified as monogenic forms of human obesity having success over common polygenic forms. In the context of molecular genetics, genome-wide association studies (GWAS) approach and their findings signified a number of genetic variants predisposing to obesity. However, the last couple of years, it has also been noticed that alterations in the environmental and epigenetic factors are one of the key causes of obesity. Hence, this review might be helpful in the current scenario of molecular genetics of human obesity, obesity-related health complications (ORHC), and energy homeostasis. Future work based on the clinical discoveries may play a role in the molecular dissection of genetic approaches to find more obesity-susceptible gene loci.
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Affiliation(s)
- Rajan Kumar Singh
- Department of Bio-Medical Sciences, School of Biosciences and Technology, VIT University, 632014 Vellore, India
| | - Permendra Kumar
- Department of Bio-Medical Sciences, School of Biosciences and Technology, VIT University, 632014 Vellore, India
| | - Kulandaivelu Mahalingam
- Department of Bio-Medical Sciences, School of Biosciences and Technology, VIT University, 632014 Vellore, India.
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22
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Navarro M. The Role of the Melanocortin System in Drug and Alcohol Abuse. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2017; 136:121-150. [DOI: 10.1016/bs.irn.2017.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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23
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You P, Hu H, Chen Y, Zhao Y, Yang Y, Wang T, Xing R, Shao Y, Zhang W, Li D, Chen H, Liu M. Effects of Melanocortin 3 and 4 Receptor Deficiency on Energy Homeostasis in Rats. Sci Rep 2016; 6:34938. [PMID: 27713523 PMCID: PMC5054679 DOI: 10.1038/srep34938] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/20/2016] [Indexed: 01/08/2023] Open
Abstract
Melanocortin-3 and 4 receptors (MC3R and MC4R) can regulate energy homeostasis, but their respective roles especially the functions of MC3R need more exploration. Here Mc3r and Mc4r single and double knockout (DKO) rats were generated using CRISPR-Cas9 system. Metabolic phenotypes were examined and data were compared systematically. Mc3r KO rats displayed hypophagia and decreased body weight, while Mc4r KO and DKO exhibited hyperphagia and increased body weight. All three mutants showed increased white adipose tissue mass and adipocyte size. Interestingly, although Mc3r KO did not show a significant elevation in lipids as seen in Mc4r KO, DKO displayed even higher lipid levels than Mc4r KO. DKO also showed more severe glucose intolerance and hyperglycaemia than Mc4r KO. These data demonstrated MC3R deficiency caused a reduction of food intake and body weight, whereas at the same time exhibited additive effects on top of MC4R deficiency on lipid and glucose metabolism. This is the first phenotypic analysis and systematic comparison of Mc3r KO, Mc4r KO and DKO rats on a homogenous genetic background. These mutant rats will be important in defining the complicated signalling pathways of MC3R and MC4R. Both Mc4r KO and DKO are good models for obesity and diabetes research.
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Affiliation(s)
- Panpan You
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Handan Hu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yuting Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yongliang Zhao
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yiqing Yang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Tongtong Wang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Roumei Xing
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yanjiao Shao
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Wen Zhang
- School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Dali Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Huaqing Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Mingyao Liu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China.,Institute of Biosciences and Technology, Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, Houston, Texas 77030, USA
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Mavrikaki M, Girardet C, Kern A, Faruzzi Brantley A, Miller CA, Macarthur H, Marks DL, Butler AA. Melanocortin-3 receptors in the limbic system mediate feeding-related motivational responses during weight loss. Mol Metab 2016; 5:566-579. [PMID: 27408780 PMCID: PMC4921936 DOI: 10.1016/j.molmet.2016.05.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 04/28/2016] [Accepted: 05/04/2016] [Indexed: 12/21/2022] Open
Abstract
Objective Appetitive responses to weight loss are mediated by a nutrient-sensing neural network comprised of melanocortin neurons. The role of neural melanocortin-3 receptors (MC3R) in mediating these responses is enigmatic. Mc3r knockout mice exhibit a paradoxical phenotype of obesity and reduced feeding-related behaviors in situations of nutrient scarcity. Here we examined whether MC3Rs expressed in mesolimbic neurons regulate feeding-related motivational responses. Methods Interactions between Mc3r genotype, cognitive function and energy balance on food self-administration were assessed using operant conditioning with fixed- and progressive ratio (FR1/PR1) settings. Inhibition of Mc3r transcription by a loxP-flanked transcriptional blocker (TB) in C57BL/6JN mice (Mc3rTB/TB) was reversed in mesolimbic neurons using DAT-Cre (DAT-MC3R). Results Caloric restriction (CR) caused 10–15% weight loss and increased motivation to acquire food rewards during training sessions. c-Fos-expression in the nucleus accumbens was increased 1 h following food presentation. While exhibiting weight loss, total food self-administration, enhanced motivation to self-administer food rewards in training sessions held during CR and c-Fos-activation in the nucleus accumbens following re-feeding were all markedly attenuated in Mc3rTB/TB mice. In contrast, cognitive abilities were normal in Mc3rTB/TB mice. Total food self-administration during FR1 sessions was not rescued in DAT-MC3R mice, however enhanced motivational responses to self-administer food rewards in PR1 conditions were restored. The nutrient-partitioning phenotype observed with Mc3r-deficiency was not rescued in DAT-MC3R mice. Conclusions Mesolimbic MC3Rs mediate enhanced motivational responses during CR. However, they are insufficient to restore normal caloric loading when food is presented during CR and do not affect metabolic conditions altering nutrient partitioning. Food-related motivational responses in mice increase with caloric restriction (CR). Melanocortin-3 receptors (MC3R) are required for food-related motivational responses. MC3Rs role in food-related motivational responses depends on metabolic condition. Mesolimbic MC3Rs increase food-related motivational responses during CR.
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Affiliation(s)
- Maria Mavrikaki
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Clemence Girardet
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Andras Kern
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Alicia Faruzzi Brantley
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA; Behavioral Core, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Courtney A Miller
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Heather Macarthur
- Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Daniel L Marks
- Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Andrew A Butler
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
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Anderson EJP, Çakir I, Carrington SJ, Cone RD, Ghamari-Langroudi M, Gillyard T, Gimenez LE, Litt MJ. 60 YEARS OF POMC: Regulation of feeding and energy homeostasis by α-MSH. J Mol Endocrinol 2016; 56:T157-74. [PMID: 26939593 PMCID: PMC5027135 DOI: 10.1530/jme-16-0014] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 03/01/2016] [Indexed: 12/20/2022]
Abstract
The melanocortin peptides derived from pro-opiomelanocortin (POMC) were originally understood in terms of the biological actions of α-melanocyte-stimulating hormone (α-MSH) on pigmentation and adrenocorticotrophic hormone on adrenocortical glucocorticoid production. However, the discovery of POMC mRNA and melanocortin peptides in the CNS generated activities directed at understanding the direct biological actions of melanocortins in the brain. Ultimately, discovery of unique melanocortin receptors expressed in the CNS, the melanocortin-3 (MC3R) and melanocortin-4 (MC4R) receptors, led to the development of pharmacological tools and genetic models leading to the demonstration that the central melanocortin system plays a critical role in the regulation of energy homeostasis. Indeed, mutations in MC4R are now known to be the most common cause of early onset syndromic obesity, accounting for 2-5% of all cases. This review discusses the history of these discoveries, as well as the latest work attempting to understand the molecular and cellular basis of regulation of feeding and energy homeostasis by the predominant melanocortin peptide in the CNS, α-MSH.
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Affiliation(s)
- Erica J P Anderson
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Isin Çakir
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Sheridan J Carrington
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Roger D Cone
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Masoud Ghamari-Langroudi
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Taneisha Gillyard
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA Meharry Medical CollegeDepartment of Neuroscience and Pharmacology, Nashville, Tennessee, USA
| | - Luis E Gimenez
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Michael J Litt
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
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SiRNA In Vivo-Targeted Delivery to Murine Dendritic Cells by Oral Administration of Recombinant Yeast. Methods Mol Biol 2016; 1364:165-81. [PMID: 26472450 DOI: 10.1007/978-1-4939-3112-5_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
SiRNA therapeutics promise a future where any target in the transcriptome could be potentially addressed. However, the delivery of SiRNAs and targeting of particular cell types or organs are major challenges. A novel, efficient, and safe delivery system for promising the introduction of SiRNAs into particular cell types within living organisms is of great significance. Our previous studies have proved that recombinant protein (MSTN) and exogenous gene (EGFP) as vaccines, and furthermore functional CD40 shRNA expression can be delivered into dendritic cells (DCs) in mouse by oral administration of recombinant yeast (Saccharomyces cerevisiae). Here, we describe the details of the promising and innovative approach based on oral administration of recombinant yeast that allows in vivo-targeted delivery of functional SiRNA to murine intestinal DCs.
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Lemche E, Chaban OS, Lemche AV. Neuroendocrinological and Epigenetic Mechanisms Subserving Autonomic Imbalance and HPA Dysfunction in the Metabolic Syndrome. Front Neurosci 2016; 10:142. [PMID: 27147943 PMCID: PMC4830841 DOI: 10.3389/fnins.2016.00142] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/21/2016] [Indexed: 12/18/2022] Open
Abstract
Impact of environmental stress upon pathophysiology of the metabolic syndrome (MetS) has been substantiated by epidemiological, psychophysiological, and endocrinological studies. This review discusses recent advances in the understanding of causative roles of nutritional factors, sympathomedullo-adrenal (SMA) and hypothalamic-pituitary adrenocortical (HPA) axes, and adipose tissue chronic low-grade inflammation processes in MetS. Disturbances in the neuroendocrine systems for leptin, melanocortin, and neuropeptide Y (NPY)/agouti-related protein systems have been found resulting directly in MetS-like conditions. The review identifies candidate risk genes from factors shown critical for the functioning of each of these neuroendocrine signaling cascades. In its meta-analytic part, recent studies in epigenetic modification (histone methylation, acetylation, phosphorylation, ubiquitination) and posttranscriptional gene regulation by microRNAs are evaluated. Several studies suggest modification mechanisms of early life stress (ELS) and diet-induced obesity (DIO) programming in the hypothalamic regions with populations of POMC-expressing neurons. Epigenetic modifications were found in cortisol (here HSD11B1 expression), melanocortin, leptin, NPY, and adiponectin genes. With respect to adiposity genes, epigenetic modifications were documented for fat mass gene cluster APOA1/C3/A4/A5, and the lipolysis gene LIPE. With regard to inflammatory, immune and subcellular metabolism, PPARG, NKBF1, TNFA, TCF7C2, and those genes expressing cytochrome P450 family enzymes involved in steroidogenesis and in hepatic lipoproteins were documented for epigenetic modifications.
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Affiliation(s)
- Erwin Lemche
- Section of Cognitive Neuropsychiatry, Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK
| | - Oleg S Chaban
- Section of Psychosomatic Medicine, Bogomolets National Medical University Kiev, Ukraine
| | - Alexandra V Lemche
- Department of Medical Science, Institute of Clinical Research Berlin, Germany
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A mouse model for a partially inactive obesity-associated human MC3R variant. Nat Commun 2016; 7:10522. [PMID: 26818770 PMCID: PMC4738366 DOI: 10.1038/ncomms10522] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/22/2015] [Indexed: 12/30/2022] Open
Abstract
We previously reported children homozygous for two MC3R sequence variants (C17A+G241A) have greater fat mass than controls. Here we show, using homozygous knock-in mouse models in which we replace murine Mc3r with wild-type human (MC3RhWT/hWT) and double-mutant (C17A+G241A) human (MC3RhDM/hDM) MC3R, that MC3RhDM/hDM have greater weight and fat mass, increased energy intake and feeding efficiency, but reduced length and fat-free mass compared with MC3RhWT/hWT. MC3RhDM/hDM mice do not have increased adipose tissue inflammatory cell infiltration or greater expression of inflammatory markers despite their greater fat mass. Serum adiponectin levels are increased in MC3RhDM/hDM mice and MC3RhDM/hDM human subjects. MC3RhDM/hDM bone- and adipose tissue-derived mesenchymal stem cells (MSCs) differentiate into adipocytes that accumulate more triglyceride than MC3RhWT/hWT MSCs. MC3RhDM/hDM impacts nutrient partitioning to generate increased adipose tissue that appears metabolically healthy. These data confirm the importance of MC3R signalling in human metabolism and suggest a previously-unrecognized role for the MC3R in adipose tissue development. The melanocortin receptor, MC3R, regulates organismal energy homeostasis. Here, Lee et al. create knock-in mice with the a mutated version of the human MC3R receptor found in obese children, and show these mice have more fat and smaller bone, yet are by and large metabolically healthy.
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Luchtman DW, Chee MJS, Doslikova B, Marks DL, Baracos VE, Colmers WF. Defense of Elevated Body Weight Setpoint in Diet-Induced Obese Rats on Low Energy Diet Is Mediated by Loss of Melanocortin Sensitivity in the Paraventricular Hypothalamic Nucleus. PLoS One 2015; 10:e0139462. [PMID: 26444289 PMCID: PMC4596859 DOI: 10.1371/journal.pone.0139462] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 09/12/2015] [Indexed: 01/15/2023] Open
Abstract
Some animals and humans fed a high-energy diet (HED) are diet-resistant (DR), remaining as lean as individuals who were naïve to HED. Other individuals become obese during HED exposure and subsequently defend the obese weight (Diet-Induced Obesity- Defenders, DIO-D) even when subsequently maintained on a low-energy diet. We hypothesized that the body weight setpoint of the DIO-D phenotype resides in the hypothalamic paraventricular nucleus (PVN), where anorexigenic melanocortins, including melanotan II (MTII), increase presynaptic GABA release, and the orexigenic neuropeptide Y (NPY) inhibits it. After prolonged return to low-energy diet, GABA inputs to PVN neurons from DIO-D rats exhibited highly attenuated responses to MTII compared with those from DR and HED-naïve rats. In DIO-D rats, melanocortin-4 receptor expression was significantly reduced in dorsomedial hypothalamus, a major source of GABA input to PVN. Unlike melanocortin responses, NPY actions in PVN of DIO-D rats were unchanged, but were reduced in neurons of the ventromedial hypothalamic nucleus; in PVN of DR rats, NPY responses were paradoxically increased. MTII-sensitivity was restored in DIO-D rats by several weeks’ refeeding with HED. The loss of melanocortin sensitivity restricted to PVN of DIO-D animals, and its restoration upon prolonged refeeding with HED suggest that their melanocortin systems retain the ability to up- and downregulate around their elevated body weight setpoint in response to longer-term changes in dietary energy density. These properties are consistent with a mechanism of body weight setpoint.
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Affiliation(s)
- Dirk W. Luchtman
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Melissa J. S. Chee
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Barbora Doslikova
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel L. Marks
- Papé Family Pediatric Research Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd. Portland, Oregon, United States of America
| | - Vickie E. Baracos
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - William F. Colmers
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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Diane A, Kupreeva M, Borthwick F, Proctor SD, Pierce WD, Vine DF. Cardiometabolic and reproductive benefits of early dietary energy restriction and voluntary exercise in an obese PCOS-prone rodent model. J Endocrinol 2015; 226:193-206. [PMID: 26187902 DOI: 10.1530/joe-14-0711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/15/2015] [Indexed: 01/11/2023]
Abstract
Polycystic ovary syndrome (PCOS) is one of the most common endocrine-metabolic disorders in women of reproductive age characterized by ovulatory dysfunction, hyperandrogenism and cardiometabolic risk. The overweight-obese PCOS phenotype appears to have exacerbated reproductive dysfunction and cardiometabolic risk. In overweight-obese adult women with PCOS, exercise and energy restricted diets have shown limited and inconsistent effects on both cardiometabolic indices and reproductive outcomes. We hypothesized that an early lifestyle intervention involving exercise and dietary energy restriction to prevent or reduce the propensity for adiposity would modulate reproductive indices and cardiometabolic risk in an obese PCOS-prone rodent model. Weanling obese PCOS-prone and Lean-Control JCR:LA-cp rodents were given a chow diet ad libitum or an energy-restricted diet combined with or without voluntary exercise (4 h/day) for 8 weeks. Dietary energy restriction and exercise lowered total body weight gain and body fat mass by 30% compared to free-fed sedentary or exercising obese PCOS-prone animals (P<0.01). Energy restriction induced an increase in exercise intensity compared to free-feeding plus exercise conditions. Energy restriction and exercise decreased fasting plasma triglycerides and apoB48 concentrations in obese PCOS-prone animals compared to free-fed and exercise or sedentary groups. The energy restriction and exercise combination in obese PCOS-prone animals significantly increased plasma sex-hormone binding globulin, hypothalamic cocaine-and amphetamine-regulated transcript (CART) and Kisspeptin mRNA expression to levels of the Lean-Control group, and this was further associated with improvements in estrous cyclicity. The combination of exercise and dietary energy restriction when initiated in early life exerts beneficial effects on cardiometabolic and reproductive indices in an obese PCOS-prone rodent model, and this may be associated with normalization of the hypothalamic neuropeptides, Kisspeptin and CART.
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Affiliation(s)
- Abdoulaye Diane
- Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada
| | - Maria Kupreeva
- Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada
| | - Faye Borthwick
- Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada
| | - Spencer D Proctor
- Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada
| | - W David Pierce
- Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada
| | - Donna F Vine
- Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada Metabolic and Cardiovascular Diseases LaboratoryAlberta Institute of Human Nutrition, Alberta Diabetes InstituteDepartment of SociologyUniversity of Alberta, Edmonton, AB, Canada
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31
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Vaanholt LM, Mitchell SE, Sinclair RE, Speakman JR. Mice that are resistant to diet-induced weight loss have greater food anticipatory activity and altered melanocortin-3 receptor (MC3R) and dopamine receptor 2 (D2) gene expression. Horm Behav 2015; 73:83-93. [PMID: 26122292 DOI: 10.1016/j.yhbeh.2015.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 06/12/2015] [Accepted: 06/13/2015] [Indexed: 11/20/2022]
Abstract
Diet-induced weight loss varies considerably between individuals, but the mechanisms driving these individual differences remain largely unknown. Here we investigated whether key neuropeptides involved in the regulation of energy balance or reward systems were differentially expressed in mice that were prone or resistant to caloric restriction (CR) induced weight loss. Mice (n=30 males and n=34 females) were fed 70% of their own baseline ad libitum intake for 25days, after which their brains were collected and expression of various neuropeptides were investigated and compared between the 10 male and 10 female mice that showed the greatest (high weight loss, HWL) or lowest weight loss (LWL) (n=40 in total). HWL mice showed a differential neuropeptide profile to LWL in both sexes, characterised by increased expression of neuropeptide Y (NPY), agouti-related peptide (AgRP), leptin receptor (ObRb), and melanocortin 3 receptor (MC3R) in the arcuate nucleus. No changes in the expression of fat mass and obesity related gene (FTO) or suppressor of cytokine signalling 3 (Socs3) were observed. Levels of dopamine D2 receptor were decreased in the nucleus accumbens in HWL compared to LWL mice. HWL mice showed a stronger increase in food anticipatory activity (FAA) in response to CR than LWL mice. These results indicate that the mice prone to diet-induced weight loss experienced greater hunger, potentially driving their elevated FAA.
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MESH Headings
- Animals
- Anticipation, Psychological/physiology
- Arcuate Nucleus of Hypothalamus/metabolism
- Caloric Restriction
- Diet, Reducing
- Energy Metabolism/genetics
- Female
- Food
- Gene Expression
- Humans
- Male
- Mice
- Mice, Obese
- Neuropeptide Y/genetics
- Neuropeptide Y/metabolism
- Obesity/diet therapy
- Obesity/genetics
- Obesity/metabolism
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Treatment Failure
- Weight Loss/genetics
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Affiliation(s)
- Lobke M Vaanholt
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
| | - Sharon E Mitchell
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK
| | - Rachel E Sinclair
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK
| | - John R Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK; State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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32
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Jackson DS, Ramachandrappa S, Clark AJ, Chan LF. Melanocortin receptor accessory proteins in adrenal disease and obesity. Front Neurosci 2015; 9:213. [PMID: 26113808 PMCID: PMC4461818 DOI: 10.3389/fnins.2015.00213] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/28/2015] [Indexed: 12/02/2022] Open
Abstract
Melanocortin receptor accessory proteins (MRAPs) are regulators of the melanocortin receptor family. MRAP is an essential accessory factor for the functional expression of the MC2R/ACTH receptor. The importance of MRAP in adrenal gland physiology is demonstrated by the clinical condition familial glucocorticoid deficiency type 2. The role of its paralog melanocortin-2-receptor accessory protein 2 (MRAP2), which is predominantly expressed in the hypothalamus including the paraventricular nucleus, has recently been linked to mammalian obesity. Whole body deletion and targeted brain specific deletion of the Mrap2 gene result in severe obesity in mice. Interestingly, Mrap2 complete knockout (KO) mice have increased body weight without detectable changes to food intake or energy expenditure. Rare heterozygous variants of MRAP2 have been found in humans with severe, early-onset obesity. In vitro data have shown that Mrap2 interaction with the melanocortin-4-receptor (Mc4r) affects receptor signaling. However, the mechanism by which Mrap2 regulates body weight in vivo is not fully understood and differences between the phenotypes of Mrap2 and Mc4r KO mice may point toward Mc4r independent mechanisms.
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Affiliation(s)
- David S Jackson
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London London, UK
| | - Shwetha Ramachandrappa
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London London, UK
| | - Adrian J Clark
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London London, UK
| | - Li F Chan
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London London, UK
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Mountjoy KG. Pro-Opiomelanocortin (POMC) Neurones, POMC-Derived Peptides, Melanocortin Receptors and Obesity: How Understanding of this System has Changed Over the Last Decade. J Neuroendocrinol 2015; 27:406-18. [PMID: 25872650 DOI: 10.1111/jne.12285] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 04/04/2015] [Accepted: 04/07/2015] [Indexed: 12/19/2022]
Abstract
Following the cloning of the melanocortin receptor and agouti protein genes, a model was developed for the central melanocortin system with respect to the regulation of energy and glucose homeostasis. This model comprised leptin regulation of melanocortin peptides and agouti-related peptide (AgRP) produced from central pro-opiomelanocortin (POMC) and AgRP neurones, respectively, as well as AgRP competitive antagonism of melanocortin peptides activating melanocortin 4 receptor (MC4R) to Gαs and the cAMP signalling pathway. In the last decade, there have been paradigm shifts in our understanding of the central melanocortin system as a result of the application of advanced new technologies, including Cre-LoxP transgenic mouse technology, pharmacogenetics and optogenetics. During this period, our understanding of G protein coupled receptor signal transduction has also dramatically changed, such that these receptors are now known to exist in the plasma membrane oscillating between various inactive and active conformational states, and the active states signal through G protein-dependent and G protein-independent pathways. The present review focuses on evidence obtained over the past decade that has changed our understanding of POMC gene expression and regulation in the central nervous system, POMC and AgRP neuronal circuitry, neuroanatomical functions of melanocortin receptors, melanocortin 3 receptor (MC3R) and MC4R, and signal transduction through MC3R and MC4R.
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Affiliation(s)
- K G Mountjoy
- Departments of Physiology and Molecular Medicine and Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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Girardet C, Mavrikaki M, Southern MR, Smith RG, Butler AA. Assessing interactions between Ghsr and Mc3r reveals a role for AgRP in the expression of food anticipatory activity in male mice. Endocrinology 2014; 155:4843-55. [PMID: 25211592 PMCID: PMC4239417 DOI: 10.1210/en.2014-1497] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The stomach hormone ghrelin and hypothalamic melanocortin neurons belong to a gut-brain circuit controlling appetite and metabolic homeostasis. Mice lacking melanocortin-3 receptor (Mc3rKO) or growth hormone secretagogue receptor (GhsrKO) genes exhibit attenuated food anticipatory activity (FAA), a rise in locomotor activity anticipating mealtime, suggesting common circuitry regulating anticipatory responses to nutrient loading. To investigate the interaction between Ghsrs and Mc3rs, we compared food anticipatory responses in GhsrKO, Mc3rKO, and double Ghsr;Mc3r knockout (DKO) mice subjected to a hypocaloric restricted feeding (RF) protocol in constant dark or 12-hour light, 12-hour dark settings. DKO are viable, exhibiting no overt behavioral or metabolic phenotypes in ad libitum or fasting conditions. FAA was initially attenuated in all mutant strains in constant darkness. However, GhsrKO eventually exhibited a robust food anticipatory response, suggesting compensation. Mc3rKO and DKO did not compensate, indicating a continued requirement for Mc3rs in maintaining the expression of FAA in situations of RF. Abnormal regulation of hypothalamic agouti-related peptide/neuropeptide Y (AgRP/Npy) neurons previously observed during fasting may contribute to attenuated FAA in Mc3rKO. AgRP and Npy expression measured 1 hour before food presentation correlated positively with FAA. Absence of Mc3rs (but not Ghsrs) was associated with lower AgRP/Npy expression, suggesting attenuated responses to signals of negative energy balance. These observations support the importance of Mc3rs as modulators of anticipatory responses to feeding, with mice able to compensate for loss of Ghsrs. The behavioral deficits of Mc3rKO displayed during RF may be partially explained by reduced hunger sensations owing to abnormal regulation of orexigenic AgRP/Npy neurons.
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Affiliation(s)
- Clemence Girardet
- Departments of Metabolism and Aging (C.G., M.M., R.G.S., A.A.B.) and Molecular Therapeutics (M.R.S.), The Scripps Research Institute, Jupiter, Florida 33458; and Department of Pharmacological and Physiological Science (C.G., M.M., A.A.B.), Saint Louis University, Saint Louis, Missouri 63104
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Bacterial ClpB heat-shock protein, an antigen-mimetic of the anorexigenic peptide α-MSH, at the origin of eating disorders. Transl Psychiatry 2014; 4:e458. [PMID: 25290265 PMCID: PMC4350527 DOI: 10.1038/tp.2014.98] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 08/13/2014] [Accepted: 08/21/2014] [Indexed: 12/12/2022] Open
Abstract
The molecular mechanisms at the origin of eating disorders (EDs), including anorexia nervosa (AN), bulimia and binge-eating disorder (BED), are currently unknown. Previous data indicated that immunoglobulins (Igs) or autoantibodies (auto-Abs) reactive with α-melanocyte-stimulating hormone (α-MSH) are involved in regulation of feeding and emotion; however, the origin of such auto-Abs is unknown. Here, using proteomics, we identified ClpB heat-shock disaggregation chaperone protein of commensal gut bacteria Escherichia coli as a conformational antigen mimetic of α-MSH. We show that ClpB-immunized mice produce anti-ClpB IgG crossreactive with α-MSH, influencing food intake, body weight, anxiety and melanocortin receptor 4 signaling. Furthermore, chronic intragastric delivery of E. coli in mice decreased food intake and stimulated formation of ClpB- and α-MSH-reactive antibodies, while ClpB-deficient E. coli did not affect food intake or antibody levels. Finally, we show that plasma levels of anti-ClpB IgG crossreactive with α-MSH are increased in patients with AN, bulimia and BED, and that the ED Inventory-2 scores in ED patients correlate with anti-ClpB IgG and IgM, which is similar to our previous findings for α-MSH auto-Abs. In conclusion, this work shows that the bacterial ClpB protein, which is present in several commensal and pathogenic microorganisms, can be responsible for the production of auto-Abs crossreactive with α-MSH, associated with altered feeding and emotion in humans with ED. Our data suggest that ClpB-expressing gut microorganisms might be involved in the etiology of EDs.
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Lute B, Jou W, Lateef DM, Goldgof M, Xiao C, Piñol RA, Kravitz AV, Miller NR, Huang YG, Girardet C, Butler AA, Gavrilova O, Reitman ML. Biphasic effect of melanocortin agonists on metabolic rate and body temperature. Cell Metab 2014; 20:333-45. [PMID: 24981835 PMCID: PMC4126889 DOI: 10.1016/j.cmet.2014.05.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 04/03/2014] [Accepted: 05/22/2014] [Indexed: 11/30/2022]
Abstract
The melanocortin system regulates metabolic homeostasis and inflammation. Melanocortin agonists have contradictorily been reported to both increase and decrease metabolic rate and body temperature. We find two distinct physiologic responses occurring at similar doses. Intraperitoneal administration of the nonselective melanocortin agonist MTII causes a melanocortin-4 receptor (Mc4r)-mediated hypermetabolism/hyperthermia. This is preceded by a profound, transient hypometabolism/hypothermia that is preserved in mice lacking any one of Mc1r, Mc3r, Mc4r, or Mc5r. Three other melanocortin agonists also caused hypothermia, which is actively achieved via seeking a cool environment, vasodilation, and inhibition of brown adipose tissue thermogenesis. These results suggest that the hypometabolic/hypothermic effect of MTII is not due to a failure of thermoregulation. The hypometabolism/hypothermia was prevented by dopamine antagonists, and MTII selectively activated arcuate nucleus dopaminergic neurons, suggesting that these neurons may contribute to the hypometabolism/hypothermia. We propose that the hypometabolism/hypothermia is a regulated response, potentially beneficial during extreme physiologic stress.
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Affiliation(s)
- Beth Lute
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - William Jou
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Dalya M Lateef
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Margalit Goldgof
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Cuiying Xiao
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Ramón A Piñol
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Alexxai V Kravitz
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Nicole R Miller
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Yuning George Huang
- Kidney Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Clemence Girardet
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Andrew A Butler
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Oksana Gavrilova
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Marc L Reitman
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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Girardet C, Begriche K, Ptitsyn A, Koza RA, Butler AA. Unravelling the mysterious roles of melanocortin-3 receptors in metabolic homeostasis and obesity using mouse genetics. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2014; 4:S37-44. [PMID: 27152165 DOI: 10.1038/ijosup.2014.10] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The central nervous melanocortin system maintains body mass and adiposity within a 'healthy' range by regulating satiety and metabolic homeostasis. Neural melanocortin-4 receptors (MC4R) modulate satiety signals and regulate autonomic outputs governing glucose and lipid metabolism in the periphery. The functions of melanocortin-3 receptors (MC3R) have been less well defined. We have observed that food anticipatory activity (FAA) is attenuated in Mc3r-/- mice housed in light:dark or constant dark conditions. Mc3r-/- mice subjected to the restricted feeding protocol that was used to induce FAA also developed insulin resistance, dyslipidaemia, impaired glucose tolerance and evidence of a cellular stress response in the liver. MC3Rs may thus function as modulators of oscillator systems that govern circadian rhythms, integrating signals from nutrient sensors to facilitate synchronizing peak foraging behaviour and metabolic efficiency with nutrient availability. To dissect the functions of MC3Rs expressed in hypothalamic and extra-hypothalamic structures, we inserted a 'lox-stop-lox' (TB) sequence into the Mc3r gene. Mc3r (TB/TB) mice recapitulate the phenotype reported for Mc3r-/- mice: increased adiposity, accelerated diet-induced obesity and attenuated FAA. The ventromedial hypothalamus exhibits high levels of Mc3r expression; however, restoring the expression of the LoxTB Mc3r allele in this nucleus did not restore FAA. However, a surprising outcome came from studies using Nestin-Cre to restore the expression of the LoxTB Mc3r allele in the nervous system. These data suggest that 'non-neural' MC3Rs have a role in the defence of body weight. Future studies examining the homeostatic functions of MC3Rs should therefore consider actions outside the central nervous system.
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Affiliation(s)
- C Girardet
- Department of Metabolism and Aging, The Scripps Research Institute , Jupiter, FL, USA
| | - K Begriche
- Department of Metabolism and Aging, The Scripps Research Institute , Jupiter, FL, USA
| | - A Ptitsyn
- The Pennington Biomedical Research Center, Louisiana State University System , Baton Rouge, LA, USA
| | - R A Koza
- The Pennington Biomedical Research Center, Louisiana State University System , Baton Rouge, LA, USA
| | - A A Butler
- Department of Metabolism and Aging, The Scripps Research Institute , Jupiter, FL, USA
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Gallo-Payet N. Central (mainly) actions of GPCRs in energy homeostasis/balance: view from the Chair. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2014; 4:S21-5. [PMID: 27152161 DOI: 10.1038/ijosup.2014.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To maintain a constant body weight, energy intake must equal energy expenditure; otherwise, there is a risk of overweight and obesity. The hypothalamus is one of the primary brain regions where multiple nutrient-related signals from peripheral and central sources converge and become integrated to regulate both short- and long-term nutritional states. The aim of the afternoon session of the 15th Annual International Symposium of the Laval University Obesity Research Chair held in Quebec City on 9 November 2012 was to present the most recent insights into the complex molecular mechanisms regulating food intake. The aims were to emphasize on the interaction between central and peripheral actions of some of the key players acting not only at the hypothalamic level but also at the periphery. Presentations were focused on melanocortin-3 receptor (MC3R) and melanin-concentrating hormone (MCH) as anorexigenic and orexigenic components of the hypothalamus, on endocannabinoid receptors, initially as a central neuromodulatory signal, and on glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) as peripheral signals. What becomes clear from these four presentations is that the regulation of food intake and energy homeostasis involves several overlapping pathways, and that we have only touched the tip of the iceberg. From the examples presented in this symposium, it could be expected that in the near future, in addition to a low-fat diet and exercise, a combination of appropriate peptides and small molecules is likely to become available to improve/facilitate the objectives of long-term maintenance of energy balance and body weight.
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Affiliation(s)
- N Gallo-Payet
- Division of Endocrinology, Department of Medicine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke , Sherbrooke, Quebec, Canada
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Switonski M, Mankowska M, Salamon S. Family of melanocortin receptor (MCR) genes in mammals-mutations, polymorphisms and phenotypic effects. J Appl Genet 2013; 54:461-72. [PMID: 23996627 PMCID: PMC3825561 DOI: 10.1007/s13353-013-0163-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 07/11/2013] [Accepted: 07/28/2013] [Indexed: 01/02/2023]
Abstract
The melanocortin receptor gene family consists of five single-exon members, which are located on autosomes. Three genes (MC2R, MC4R and MC5R) are syntenic in the human, mouse, cattle and dog genomes, while in the pig, the syntenic group comprises MC1R, MC2R and MC5R. Two genes (MC1R and MC4R) have been extensively studied due to their function in melanogenesis (MC1R) and energy control (MC4R). Conservative organisation of these genes in five mammalian species (human, mouse, cattle, pig and dog), in terms of the encoded amino acid sequence, is higher in the case of MC4R compared to MC1R. Polymorphisms of these two genes are responsible or associated with variation of pigmentation (MC1R) and adipose tissue deposition (MC4R). Polymorphic variants in MC1R, causing coat colour variation, were described in humans and domestic mammals (cattle, horse, pig, sheep, dog), as well as farm red and arctic foxes. The MC4R gene is very polymorphic in humans and it is well known that some variants cause monogenic obesity or significantly contribute to the development of polygenic obesity. Such relationships are not so evident in domestic mammals; however, at least one missense substitution (298Asp > Asn) in the porcine MC4R significantly contributes, at least in some breeds, to fat tissue accumulation, feed conversion ratio and daily weight gain. Knowledge on the phenotypic effects of polymorphisms of MC2R, MC3R and MC5R in domestic mammals is scarce, probably due to the small number of reports addressing these genes. Thus, further studies focused on these genes should be undertaken.
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Affiliation(s)
- M Switonski
- Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland,
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Girardet C, Butler AA. Neural melanocortin receptors in obesity and related metabolic disorders. Biochim Biophys Acta Mol Basis Dis 2013; 1842:482-94. [PMID: 23680515 DOI: 10.1016/j.bbadis.2013.05.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/16/2013] [Accepted: 05/03/2013] [Indexed: 12/11/2022]
Abstract
Obesity is a global health issue, as it is associated with increased risk of developing chronic conditions associated with disorders of metabolism such as type 2 diabetes and cardiovascular disease. A better understanding of how excessive fat accumulation develops and causes diseases of the metabolic syndrome is urgently needed. The hypothalamic melanocortin system is an important point of convergence connecting signals of metabolic status with the neural circuitry that governs appetite and the autonomic and neuroendocrine system controling metabolism. This system has a critical role in the defense of body weight and maintenance of homeostasis. Two neural melanocortin receptors, melanocortin 3 and 4 receptors (MC3R and MC4R), play crucial roles in the regulation of energy balance. Mutations in the MC4R gene are the most common cause of monogenic obesity in humans, and a large literature indicates a role in regulating both energy intake through the control of satiety and energy expenditure. In contrast, MC3Rs have a more subtle role in energy homeostasis. Results from our lab indicate an important role for MC3Rs in synchronizing rhythms in foraging behavior with caloric cues and maintaining metabolic homeostasis during periods of nutrient scarcity. However, while deletion of the Mc3r gene in mice alters nutrient partitioning to favor accumulation of fat mass no obvious role for MC3R haploinsufficiency in human obesity has been reported. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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MESH Headings
- Animals
- Body Weight/genetics
- Cardiovascular Diseases/complications
- Cardiovascular Diseases/metabolism
- Cardiovascular Diseases/pathology
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Humans
- Metabolic Diseases/genetics
- Metabolic Diseases/metabolism
- Metabolic Diseases/pathology
- Mice
- Obesity/complications
- Obesity/genetics
- Obesity/metabolism
- Obesity/pathology
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
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Affiliation(s)
- Clemence Girardet
- Department of Metabolism and Aging, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Andrew A Butler
- Department of Metabolism and Aging, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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41
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Byerly MS, Al Salayta M, Swanson RD, Kwon K, Peterson JM, Wei Z, Aja S, Moran TH, Blackshaw S, Wong GW. Estrogen-related receptor β deletion modulates whole-body energy balance via estrogen-related receptor γ and attenuates neuropeptide Y gene expression. Eur J Neurosci 2013; 37:1033-47. [PMID: 23360481 DOI: 10.1111/ejn.12122] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 12/05/2012] [Accepted: 12/06/2012] [Indexed: 12/23/2022]
Abstract
Estrogen-related receptors (ERRs) α, β and γ are orphan nuclear hormone receptors with no known ligands. Little is known concerning the role of ERRβ in energy homeostasis, as complete ERRβ-null mice die mid-gestation. We generated two viable conditional ERRβ-null mouse models to address its metabolic function. Whole-body deletion of ERRβ in Sox2-Cre:ERRβ(lox/lox) mice resulted in major alterations in body composition, metabolic rate, meal patterns and voluntary physical activity levels. Nestin-Cre:ERRβ(lox/lox) mice exhibited decreased expression of ERRβ in hindbrain neurons, the predominant site of expression, decreased neuropeptide Y (NPY) gene expression in the hindbrain, increased lean body mass, insulin sensitivity, increased energy expenditure, decreased satiety and decreased time between meals. In the absence of ERRβ, increased ERRγ signaling decreased satiety and the duration of time between meals, similar to meal patterns observed for both the Sox2-Cre:ERRβ(lox/lox) and Nestin-Cre:ERRβ(lox/lox) strains of mice. Central and/or peripheral ERRγ signaling may modulate these phenotypes by decreasing NPY gene expression. Overall, the relative expression ratio between ERRβ and ERRγ may be important in modulating ingestive behavior, specifically satiety, gene expression, as well as whole-body energy balance.
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Affiliation(s)
- Mardi S Byerly
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Roa J. Role of GnRH Neurons and Their Neuronal Afferents as Key Integrators between Food Intake Regulatory Signals and the Control of Reproduction. Int J Endocrinol 2013; 2013:518046. [PMID: 24101924 PMCID: PMC3786537 DOI: 10.1155/2013/518046] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/07/2013] [Indexed: 11/17/2022] Open
Abstract
Reproductive function is regulated by a plethora of signals that integrate physiological and environmental information. Among others, metabolic factors are key components of this circuit since they inform about the propitious timing for reproduction depending on energy availability. This information is processed mainly at the hypothalamus that, in turn, modulates gonadotropin release from the pituitary and, thereby, gonadal activity. Metabolic hormones, such as leptin, insulin, and ghrelin, act as indicators of the energy status and convey this information to the reproductive axis regulating its activity. In this review, we will analyse the central mechanisms involved in the integration of this metabolic information and their contribution to the control of the reproductive function. Particular attention will be paid to summarize the participation of GnRH, Kiss1, NPY, and POMC neurons in this process and their possible interactions to contribute to the metabolic control of reproduction.
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Affiliation(s)
- Juan Roa
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Avenida Menéndez Pidal s/n, 14004 Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Spain
- Instituto Maimónides de Investigaciones Biomédicas (IMIBIC)/Hospital Universitario Reina Sofia, Córdoba, Spain
- *Juan Roa:
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Begriche K, Girardet C, McDonald P, Butler AA. Melanocortin-3 receptors and metabolic homeostasis. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 114:109-46. [PMID: 23317784 DOI: 10.1016/b978-0-12-386933-3.00004-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Attenuated activity of the central nervous melanocortin system causes obesity and insulin resistance. Obese rodents treated with melanocortins exhibit improvements in obesity and metabolic homeostasis that are not mutually dependent, suggesting metabolic actions that are independent of weight changes. These responses are generally thought to involve G-protein-coupled receptors expressed in the brain. Melanocortin-4 receptors (MC4Rs) regulate satiety and autonomic nervous system and thyroid function. MC3Rs are expressed in hypothalamic and limbic regions involved in controlling ingestive behaviors and autonomic function. Mc3r-/- mice exhibit increased adiposity and an accelerated diet-induced obesity. While this phenotype is not dependent on hyperphagia, data on the regulation of food intake by MC3Rs are inconsistent. Recent investigations by our laboratory suggest a unique combination of behavioral and metabolic disorders in Mc3r-/- mice. MC3Rs are critical for the expression of the anticipatory response and metabolic homeostasis when food intake occurs outside the normal voluntary rhythms driven by photoperiod. Using a Cre-Lox strategy, we can now investigate MC3Rs expressed in different brain regions and organ systems in the periphery. While focusing on the functions of neural MC3Rs, early results suggest an additional layer of complexity with central and peripheral MC3Rs involved in the defense of body weight.
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Affiliation(s)
- Karima Begriche
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, Florida, USA
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Roa J, Herbison AE. Direct regulation of GnRH neuron excitability by arcuate nucleus POMC and NPY neuron neuropeptides in female mice. Endocrinology 2012; 153:5587-99. [PMID: 22948210 DOI: 10.1210/en.2012-1470] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons act to sense and coordinate the brain's responses to metabolic cues. One neuronal network that is very sensitive to metabolic status is that controlling fertility. In this study, we investigated the impact of neuropeptides released by NPY and POMC neurons on the cellular excitability of GnRH neurons, the final output cells of the brain controlling fertility. The majority (∼70%) of GnRH neurons were activated by α-melanocyte-stimulating hormone, and this resulted from the direct postsynaptic activation of melanocortin receptor 3 and melanocortin receptor 4. A small population of GnRH neurons (∼15%) was excited by cocaine and amphetamine-regulated transcript or inhibited by β-endorphin. Agouti-related peptide, released by NPY neurons, was found to have variable inhibitory (∼10%) and stimulatory (∼25%) effects upon subpopulations of GnRH neurons. A variety of NPY and pancreatic polypeptide analogs was used to examine potential NPY interactions with GnRH neurons. Although porcine NPY (Y1/Y2/Y5 agonist) directly inhibited the firing of approximately 45% of GnRH neurons, [Leu(31),Pro(34)]-NPY (Y1/Y4/Y5 agonist) could excite (56%) or inhibit (19%). Experiments with further agonists indicated that Y1 receptors were responsible for suppressing GnRH neuron activity, whereas postsynaptic Y4 receptors were stimulatory. These results show that the activity of GnRH neurons is regulated in a complex manner by neuropeptides released by POMC and NPY neurons. This provides a direct route through which different metabolic cues can regulate fertility.
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Affiliation(s)
- Juan Roa
- Centre for Neuroendocrinology, Department of Physiology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Fox EA, Biddinger JE, Jones KR, McAdams J, Worman A. Mechanism of hyperphagia contributing to obesity in brain-derived neurotrophic factor knockout mice. Neuroscience 2012; 229:176-99. [PMID: 23069761 DOI: 10.1016/j.neuroscience.2012.09.078] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 09/28/2012] [Accepted: 09/28/2012] [Indexed: 10/27/2022]
Abstract
Global-heterozygous and brain-specific homozygous knockouts (KOs) of brain-derived neurotrophic factor (BDNF) cause late- and early-onset obesity, respectively, both involving hyperphagia. Little is known about the mechanism underlying this hyperphagia or whether BDNF loss from peripheral tissues could contribute to overeating. Since global-homozygous BDNF-KO is perinatal lethal, a BDNF-KO that spared sufficient brainstem BDNF to support normal health was utilized to begin to address these issues. Meal pattern and microstructure analyses suggested overeating of BDNF-KO mice was mediated by deficits in both satiation and satiety that resulted in increased meal size and frequency and implicated a reduction of vagal signaling from the gut to the brain. Meal-induced c-Fos activation in the nucleus of the solitary tract, a more direct measure of vagal afferent signaling, however, was not decreased in BDNF-KO mice, and thus was not consistent with a vagal afferent role. Interestingly though, meal-induced c-Fos activation was increased in the dorsal motor nucleus of the vagus nerve (DMV) of BDNF-KO mice. This could imply that augmentation of vago-vagal digestive reflexes occurred (e.g., accommodation), which would support increased meal size and possibly increased meal number by reducing the increase in intragastric pressure produced by a given amount of ingesta. Additionally, vagal sensory neuron number in BDNF-KO mice was altered in a manner consistent with the increased meal-induced activation of the DMV. These results suggest reduced BDNF causes satiety and satiation deficits that support hyperphagia, possibly involving augmentation of vago-vagal reflexes mediated by central pathways or vagal afferents regulated by BDNF levels.
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Affiliation(s)
- E A Fox
- Behavioral Neurogenetics Laboratory, Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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46
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Affiliation(s)
- Andrew A Butler
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, Florida, USA.
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47
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Begriche K, Marston OJ, Rossi J, Burke LK, McDonald P, Heisler LK, Butler AA. Melanocortin-3 receptors are involved in adaptation to restricted feeding. GENES, BRAIN, AND BEHAVIOR 2012; 11:291-302. [PMID: 22353545 PMCID: PMC3319531 DOI: 10.1111/j.1601-183x.2012.00766.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 01/09/2012] [Accepted: 01/12/2012] [Indexed: 11/29/2022]
Abstract
The central nervous melanocortin system forms a neural network that maintains energy homeostasis. Actions involving neural melanocortin-3 receptors (MC3Rs) regulate the expression rhythms in ingestive behaviors and metabolism anticipating nutrient intake. Here, we characterized the response of Mc3r knockout (Mc3r(-/-)) and wild type (WT) mice to a restricted feeding (RF) schedule where food access was limited to a 4-h period mid light cycle using a mechanical barrier. Mc3r(-/-) mice adapted poorly to the food restriction schedule. Anticipatory activity and the initial bout of intense feeding activity associated with granting food access were attenuated in Mc3r(-/-) mice, resulting in increased weight loss relative to controls. To investigate whether activity in specific hypothalamic nuclei contribute to the Mc3r(-/-) phenotype observed, we assessed hypothalamic FOS-immunoreactivity (FOS-IR) associated with food restriction. Food access markedly increased FOS-IR in the dorsomedial hypothalamus (DMH), but not in the suprachiasmatic or ventromedial hypothalamic nuclei (SCN and VMN, respectively) compared to ad libitum fed mice. Mc3r(-/-) mice displayed a significant reduction in FOS-IR in the DMH during feeding. Analysis of MC3R signaling in vitro indicated dose-dependent stimulation of the extracellular signal-regulated kinase (ERK) pathway by the MC3R agonist d-Trp(8)-γMSH. Treatment of WT mice with d-Trp(8)-γMSH administered intracerebroventricularly increased the number of pERK neurons 1.7-fold in the DMH. These observations provide further support for the involvement of the MC3Rs in regulating adaptation to food restriction. Moreover, MC3Rs may modulate the activity of neurons in the DMH, a region previously linked to the expression of the anticipatory response to RF.
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Affiliation(s)
- K Begriche
- Department of Metabolism and Aging, The Scripps Research InstituteJupiter, FL, USA
| | - O J Marston
- Department of Pharmacology, University of CambridgeCambridge, United Kingdom
| | - J Rossi
- Department of Metabolism and Aging, The Scripps Research InstituteJupiter, FL, USA
| | - L K Burke
- Department of Pharmacology, University of CambridgeCambridge, United Kingdom
| | - P McDonald
- Department of Molecular Therapeutics and Translational Research Institute, The Scripps Research InstituteJupiter, FL, USA
| | - L K Heisler
- Department of Pharmacology, University of CambridgeCambridge, United Kingdom
| | - A A Butler
- Department of Metabolism and Aging, The Scripps Research InstituteJupiter, FL, USA
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