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Martins FF, Santos-Reis T, Marinho TS, Aguila MB, Mandarim-de-Lacerda CA. Hypothalamic anorexigenic signaling pathways (leptin, amylin, and proopiomelanocortin) are semaglutide (GLP-1 analog) targets in obesity control in mice. Life Sci 2023; 313:121268. [PMID: 36493878 DOI: 10.1016/j.lfs.2022.121268] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/23/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022]
Affiliation(s)
- Fabiane Ferreira Martins
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, The University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thiago Santos-Reis
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, The University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thatiany Souza Marinho
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, The University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marcia Barbosa Aguila
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, The University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Carlos Alberto Mandarim-de-Lacerda
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, The University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
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2
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Corrigan RR, Labrador L, Grizzanti J, Mey M, Piontkivska H, Casadesús G. Neuroprotective Mechanisms of Amylin Receptor Activation, Not Antagonism, in the APP/PS1 Mouse Model of Alzheimer's Disease. J Alzheimers Dis 2023; 91:1495-1514. [PMID: 36641678 DOI: 10.3233/jad-221057] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Amylin, a pancreatic amyloid peptide involved in energy homeostasis, is increasingly studied in the context of Alzheimer's disease (AD) etiology. To date, conflicting pathogenic and neuroprotective roles for this peptide and its analogs for AD pathogenesis have been described. OBJECTIVE Whether the benefits of amylin are associated with peripheral improvement of metabolic tone/function or directly through the activation of central amylin receptors is also unknown and downstream signaling mechanisms of amylin receptors are major objectives of this study. METHODS To address these questions more directly we delivered the amylin analog pramlintide systemically (IP), at previously identified therapeutic doses, while centrally (ICV) inhibiting the receptor using an amylin receptor antagonist (AC187), at doses known to impact CNS function. RESULTS Here we show that pramlintide improved cognitive function independently of CNS receptor activation and provide transcriptomic data that highlights potential mechanisms. Furthermore, we show than inhibition of the amylin receptor increased amyloid-beta pathology in female APP/PS1 mice, an effect than was mitigated by peripheral delivery of pramlintide. Through transcriptomic analysis of pramlintide therapy in AD-modeled mice we found sexual dimorphic modulation of neuroprotective mechanisms: oxidative stress protection in females and membrane stability and reduced neuronal excitability markers in males. CONCLUSION These data suggest an uncoupling of functional and pathology-related events and highlighting a more complex receptor system and pharmacological relationship that must be carefully studied to clarify the role of amylin in CNS function and AD.
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Affiliation(s)
| | - Luis Labrador
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - John Grizzanti
- School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Megan Mey
- School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Helen Piontkivska
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Gemma Casadesús
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
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3
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Lu J, Piper SJ, Zhao P, Miller LJ, Wootten D, Sexton PM. Targeting VIP and PACAP Receptor Signaling: New Insights into Designing Drugs for the PACAP Subfamily of Receptors. Int J Mol Sci 2022; 23:8069. [PMID: 35897648 PMCID: PMC9331257 DOI: 10.3390/ijms23158069] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 12/16/2022] Open
Abstract
Pituitary Adenylate Cyclase-Activating Peptide (PACAP) and Vasoactive Intestinal Peptide (VIP) are neuropeptides involved in a diverse array of physiological and pathological processes through activating the PACAP subfamily of class B1 G protein-coupled receptors (GPCRs): VIP receptor 1 (VPAC1R), VIP receptor 2 (VPAC2R), and PACAP type I receptor (PAC1R). VIP and PACAP share nearly 70% amino acid sequence identity, while their receptors PAC1R, VPAC1R, and VPAC2R share 60% homology in the transmembrane regions of the receptor. PACAP binds with high affinity to all three receptors, while VIP binds with high affinity to VPAC1R and VPAC2R, and has a thousand-fold lower affinity for PAC1R compared to PACAP. Due to the wide distribution of VIP and PACAP receptors in the body, potential therapeutic applications of drugs targeting these receptors, as well as expected undesired side effects, are numerous. Designing selective therapeutics targeting these receptors remains challenging due to their structural similarities. This review discusses recent discoveries on the molecular mechanisms involved in the selectivity and signaling of the PACAP subfamily of receptors, and future considerations for therapeutic targeting.
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Affiliation(s)
- Jessica Lu
- Drug Discovery Biology, Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Sarah J Piper
- Drug Discovery Biology, Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Peishen Zhao
- Drug Discovery Biology, Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - Denise Wootten
- Drug Discovery Biology, Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
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Hage La Cour S, Juhler K, Kogelman LJA, Olesen J, Klærke DA, Kristensen DM, Jansen-Olesen I. Characterization of erenumab and rimegepant on calcitonin gene-related peptide induced responses in Xenopus Laevis oocytes expressing the calcitonin gene-related peptide receptor and the amylin-1 receptor. J Headache Pain 2022; 23:59. [PMID: 35614383 PMCID: PMC9134599 DOI: 10.1186/s10194-022-01425-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/28/2022] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The clinical use of calcitonin gene-related peptide receptor (CGRP-R) antagonists and monoclonal antibodies against CGRP and CGRP-R has offered new treatment possibilities for migraine patients. CGRP activates both the CGRP-R and structurally related amylin 1 receptor (AMY1-R). The relative effect of erenumab and the small-molecule CGRP-R antagonist, rimegepant, towards the CGRP-R and AMY-R needs to be further characterized. METHODS The effect of CGRP and two CGRP-R antagonists were examined in Xenopus laevis oocytes expressing human CGRP-R, human AMY1-R and their subunits. RESULTS CGRP administered to receptor expressing oocytes induced a concentration-dependent increase in current with the order of potency CGRP-R> > AMY1-R > calcitonin receptor (CTR). There was no effect on single components of the CGRP-R; calcitonin receptor-like receptor and receptor activity-modifying protein 1. Amylin was only effective on AMY1-R and CTR. Inhibition potencies (pIC50 values) for erenumab on CGRP induced currents were 10.86 and 9.35 for CGRP-R and AMY1-R, respectively. Rimegepant inhibited CGRP induced currents with pIC50 values of 11.30 and 9.91 for CGRP-R and AMY1-R, respectively. CONCLUSION Our results demonstrate that erenumab and rimegepant are potent antagonists of CGRP-R and AMY1-R with 32- and 25-times preference for the CGRP-R over the AMY1-R, respectively. It is discussed if this difference in affinity between the two receptors is the likely reason why constipation is a common and serious adverse effect during CGRP-R antagonism but less so with CGRP binding antibodies.
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Affiliation(s)
- Sanne Hage La Cour
- Danish Headache Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Kiki Juhler
- Danish Headache Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Lisette J A Kogelman
- Danish Headache Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jes Olesen
- Danish Headache Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Dan Arne Klærke
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - David Møbjerg Kristensen
- Danish Headache Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Inserm (Institut national de la santé et de la recherche médicale), Irset - Inserm UMR 1085, Rennes, France
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Inger Jansen-Olesen
- Danish Headache Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
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Shao L, Chen Y, Zhang S, Zhang Z, Cao Y, Yang D, Wang MW. Modulating effects of RAMPs on signaling profiles of the glucagon receptor family. Acta Pharm Sin B 2022; 12:637-650. [PMID: 35256936 PMCID: PMC8897147 DOI: 10.1016/j.apsb.2021.07.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/04/2021] [Accepted: 07/07/2021] [Indexed: 02/06/2023] Open
Abstract
Receptor activity-modulating proteins (RAMPs) are accessory molecules that form complexes with specific G protein-coupled receptors (GPCRs) and modulate their functions. It is established that RAMP interacts with the glucagon receptor family of GPCRs but the underlying mechanism is poorly understood. In this study, we used a bioluminescence resonance energy transfer (BRET) approach to comprehensively investigate such interactions. In conjunction with cAMP accumulation, Gαq activation and β-arrestin1/2 recruitment assays, we not only verified the GPCR–RAMP pairs previously reported, but also identified new patterns of GPCR–RAMP interaction. While RAMP1 was able to modify the three signaling events elicited by both glucagon receptor (GCGR) and glucagon-like peptide-1 receptor (GLP-1R), and RAMP2 mainly affected β-arrestin1/2 recruitment by GCGR, GLP-1R and glucagon-like peptide-2 receptor, RAMP3 showed a widespread negative impact on all the family members except for growth hormone-releasing hormone receptor covering the three pathways. Our results suggest that RAMP modulates both G protein dependent and independent signal transduction among the glucagon receptor family members in a receptor-specific manner. Mapping such interactions provides new insights into the role of RAMP in ligand recognition and receptor activation.
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Key Words
- AMY, amylin
- Allosteric modulation
- BRET, bioluminescence resonance energy transfer
- Bmax, maximum measured BRET value
- CGRP, calcitonin gene-related peptide
- CLR, calcitonin-like receptor
- EC50, half maximal effective concentration
- ECD, extracellular domain
- Emax, maximal response
- G protein-coupled receptor
- GCGR, glucagon receptor
- GHRHR, hormone-releasing hormone receptor
- GIPR, gastric inhibitory polypeptide receptor or glucose-dependent insulinotropic polypeptide
- GLP-1R, glucagon-like peptide-1 receptor
- GLP-2R, glucagon-like peptide-2 receptor
- GPCRs, G protein-coupled receptors
- GPCR–RAMP interaction
- Glucagon receptor family
- Ligand selectivity
- RAMP, receptor activity-modulating protein
- Receptor activity-modulating protein
- Receptor pharmacology
- Rluc, Renilla luciferase
- SBA, suspension bead array
- SCTR, secretin receptor
- SV, splice variant
- Signaling
- TMD, transmembrane domain
- VPAC2R, vasoactive intestinal polypeptide 2 receptor
- cAMP, cyclic adenosine monophosphate
- pEC50, negative logarithm of EC50
- β2-AR, β2-adrenergic receptor
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Affiliation(s)
- Lijun Shao
- The National Center for Drug Screening and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Chen
- School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Shikai Zhang
- Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200082, China
| | - Zhihui Zhang
- Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200082, China
| | - Yongbing Cao
- Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200082, China
| | - Dehua Yang
- The National Center for Drug Screening and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Corresponding authors.
| | - Ming-Wei Wang
- The National Center for Drug Screening and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- School of Pharmacy, Fudan University, Shanghai 201203, China
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Corresponding authors.
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6
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Corrigan RR, Piontkivska H, Casadesus G. Amylin Pharmacology in Alzheimer's Disease Pathogenesis and Treatment. Curr Neuropharmacol 2022; 20:1894-1907. [PMID: 34852745 PMCID: PMC9886804 DOI: 10.2174/1570159x19666211201093147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/12/2021] [Accepted: 11/26/2021] [Indexed: 11/22/2022] Open
Abstract
The metabolic peptide hormone amylin, in concert with other metabolic peptides like insulin and leptin, has an important role in metabolic homeostasis and has been intimately linked to Alzheimer's disease (AD). Interestingly, this pancreatic amyloid peptide is known to self-aggregate much like amyloid-beta and has been reported to be a source of pathogenesis in both Type II diabetes mellitus (T2DM) and Alzheimer's disease. The traditional "gain of toxic function" properties assigned to amyloid proteins are, however, contrasted by several reports highlighting neuroprotective effects of amylin and a recombinant analog, pramlintide, in the context of these two diseases. This suggests that pharmacological therapies aimed at modulating the amylin receptor may be therapeutically beneficial for AD development, as they already are for T2DMM. However, the nature of amylin receptor signaling is highly complex and not well studied in the context of CNS function. Therefore, to begin to address this pharmacological paradox in amylin research, the goal of this review is to summarize the current research on amylin signaling and CNS functions and critically address the paradoxical nature of this hormone's signaling in the context of AD pathogenesis.
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Affiliation(s)
| | | | - Gemma Casadesus
- Address correspondence to this author at the Department of Pharmacology and Therapeutics, University of Florida, PO Box 100495. Gainesville, FL32610 USA; Tel: 352-294-5346; E-mail:
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7
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Role of Receptors in Relation to Plaques and Tangles in Alzheimer's Disease Pathology. Int J Mol Sci 2021; 22:ijms222312987. [PMID: 34884789 PMCID: PMC8657621 DOI: 10.3390/ijms222312987] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/26/2021] [Accepted: 11/28/2021] [Indexed: 12/23/2022] Open
Abstract
Despite the identification of Aβ plaques and NFTs as biomarkers for Alzheimer’s disease (AD) pathology, therapeutic interventions remain elusive, with neither an absolute prophylactic nor a curative medication available to impede the progression of AD presently available. Current approaches focus on symptomatic treatments to maintain AD patients’ mental stability and behavioral symptoms by decreasing neuronal degeneration; however, the complexity of AD pathology requires a wide range of therapeutic approaches for both preventive and curative treatments. In this regard, this review summarizes the role of receptors as a potential target for treating AD and focuses on the path of major receptors which are responsible for AD progression. This review gives an overall idea centering on major receptors, their agonist and antagonist and future prospects of viral mimicry in AD pathology. This article aims to provide researchers and developers a comprehensive idea about the different receptors involved in AD pathogenesis that may lead to finding a new therapeutic strategy to treat AD.
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Stein LM, McGrath LE, Lhamo R, Koch-Laskowski K, Fortin SM, Skarbaliene J, Baader-Pagler T, Just R, Hayes MR, Mietlicki-Baase EG. The long-acting amylin/calcitonin receptor agonist ZP5461 suppresses food intake and body weight in male rats. Am J Physiol Regul Integr Comp Physiol 2021; 321:R250-R259. [PMID: 34259025 PMCID: PMC8409915 DOI: 10.1152/ajpregu.00337.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 06/30/2021] [Accepted: 07/04/2021] [Indexed: 01/18/2023]
Abstract
The peptide hormone amylin reduces food intake and body weight and is an attractive candidate target for novel pharmacotherapies to treat obesity. However, the short half-life of native amylin and amylin analogs like pramlintide limits these compounds' potential utility in promoting sustained negative energy balance. Here, we evaluate the ability of the novel long-acting amylin/calcitonin receptor agonist ZP5461 to reduce feeding and body weight in rats, and also test the role of calcitonin receptors (CTRs) in the dorsal vagal complex (DVC) of the hindbrain in the energy balance effects of chronic ZP5461 administration. Acute dose-response studies indicate that systemic ZP5461 (0.5-3 nmol/kg) robustly suppresses energy intake and body weight gain in chow- and high-fat diet (HFD)-fed rats. When HFD-fed rats received chronic systemic administration of ZP5461 (1-2 nmol/kg), the compound initially produced reductions in energy intake and weight gain but failed to produce sustained suppression of intake and body weight. Using virally mediated knockdown of DVC CTRs, the ability of chronic systemic ZP5461 to promote early reductions in intake and body weight gain was determined to be mediated in part by activation of DVC CTRs, implicating the DVC as a central site of action for ZP5461. Future studies should address other dosing regimens of ZP5461 to determine whether an alternative dose/frequency of administration would produce more sustained body weight suppression.
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Affiliation(s)
- Lauren M Stein
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Lauren E McGrath
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rinzin Lhamo
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kieran Koch-Laskowski
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Samantha M Fortin
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | | | | | - Matthew R Hayes
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Elizabeth G Mietlicki-Baase
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, State University of New York, Buffalo, New York
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9
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Distributed amylin receptor signaling and its influence on motivated behavior. Physiol Behav 2020; 222:112958. [DOI: 10.1016/j.physbeh.2020.112958] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 04/11/2020] [Accepted: 04/30/2020] [Indexed: 12/11/2022]
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10
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Nashawi H, Gustafson TJ, Mietlicki-Baase EG. Palatable food access impacts expression of amylin receptor components in the mesocorticolimbic system. Exp Physiol 2020; 105:1012-1024. [PMID: 32306457 DOI: 10.1113/ep088356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/14/2020] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the central question of this study? We tested whether intra-nucleus accumbens core amylin receptor (AmyR) activation suppresses feeding and evaluated whether intake of palatable food influences mesocorticolimbic AmyR expression. What is the main finding and its importance? Intra-nucleus accumbens core AmyR activation reduces food intake in some dietary conditions. We showed that all components of the AmyR are expressed in the prefrontal cortex and central nucleus of the amygdala and demonstrated that access to fat impacts AmyR expression in these and other mesocorticolimbic nuclei. These results suggest that the intake of palatable food might alter amylin signalling in the brain and shed further light onto potential sites of action for amylin. ABSTRACT Amylin is a pancreas- and brain-derived peptide that acts within the CNS to promote negative energy balance. However, our understanding of the CNS sites of action for amylin remains incomplete. Here, we investigate the effect of amylin receptor (AmyR) activation in the nucleus accumbens core (NAcC) on the intake of bland and palatable foods. Intra-NAcC injection of the AmyR agonist salmon calcitonin or amylin itself in male chow-fed rats had no effect on food intake, meal size or number of meals. However, in chow-fed rats with access to fat solution, although fat intake was not affected by intra-NAcC AmyR activation, subsequent chow intake was suppressed. Given that mesolimbic AmyR activation suppresses energy intake in rats with access to fat solution, we tested whether fat access changes AmyR expression in key mesocorticolimbic nuclei. Fat exposure did not affect NAcC AmyR expression, whereas in the accumbens shell, expression of receptor activity modifying protein (RAMP) 3 was significantly reduced in fat-consuming rats. We show that all components of AmyRs are expressed in the medial prefrontal cortex and central nucleus of the amygdala; fat access significantly reduced expression of calcitonin receptor-A in the central nucleus of the amygdala and RAMP2 in the medial prefrontal cortex. Taken together, these results indicate that intra-NAcC AmyR activation can suppress energy intake and, furthermore, suggest that AmyR signalling in a broader range of mesocorticolimbic sites might have a role in mediating the effects of amylin on food intake and body weight.
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Affiliation(s)
- Houda Nashawi
- Neuroscience Program, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Tyler J Gustafson
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Elizabeth G Mietlicki-Baase
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, State University of New York, Buffalo, NY, USA.,Center for Ingestive Behavior Research, University at Buffalo, State University of New York, Buffalo, NY, USA
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English A, Irwin N. Nonclassical Islet Peptides: Pancreatic and Extrapancreatic Actions. CLINICAL MEDICINE INSIGHTS-ENDOCRINOLOGY AND DIABETES 2019; 12:1179551419888871. [PMID: 32425629 PMCID: PMC7216561 DOI: 10.1177/1179551419888871] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 10/21/2019] [Indexed: 02/06/2023]
Abstract
The pancreas has physiologically important endocrine and exocrine functions; secreting enzymes into the small intestine to aid digestion and releasing multiple peptide hormones via the islets of Langerhans to regulate glucose metabolism, respectively. Insulin and glucagon, in combination with ghrelin, pancreatic polypeptide and somatostatin, are the main classical islet peptides critical for the maintenance of blood glucose. However, pancreatic islets also synthesis numerous ‘nonclassical’ peptides that have recently been demonstrated to exert fundamental effects on overall islet function and metabolism. As such, insights into the physiological relevance of these nonclassical peptides have shown impact on glucose metabolism, insulin action, cell survival, weight loss, and energy expenditure. This review will focus on the role of individual nonclassical islet peptides to stimulate pancreatic islet secretions as well as regulate metabolism. In addition, the more recognised actions of these peptides on satiety and energy regulation will also be considered. Furthermore, recent advances in the field of peptide therapeutics and obesity-diabetes have focused on the benefits of simultaneously targeting several hormone receptor signalling cascades. The potential for nonclassical islet hormones within such combinational approaches will also be discussed.
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Affiliation(s)
- Andrew English
- School of Pharmacy and Pharmaceutical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- School of Pharmacy and Pharmaceutical Sciences, Ulster University, Coleraine, Northern Ireland, UK
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12
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The BDNF Protein and its Cognate mRNAs in the Rat Spinal Cord during Amylin-induced Reversal of Morphine Tolerance. Neuroscience 2019; 422:54-64. [PMID: 31689388 DOI: 10.1016/j.neuroscience.2019.09.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/24/2019] [Accepted: 09/26/2019] [Indexed: 12/21/2022]
Abstract
The pancreatic peptide, Amylin (AMY), reportedly affects nociception in rodents. Here, we investigated the potential effect of AMY on the tolerance to morphine and on the expression of BDNF at both levels of protein and RNA in the lumbar spinal cord of morphine tolerant rats. Animals in both groups of control and test received a single daily dose of intrathecal (i.t.) morphine for 10 days. Rats in the test group received AMY (1, 10 and 60 pmoles) in addition to morphine from days 6 to10. Morphine tolerance was established at day 5. AMY alone showed enduring antinociceptive effects for 10 days. Real-Time PCR, western blotting and ELISA were used respectively to assess levels of BDNF transcripts and their encoded proteins. Rats tolerant to i.t. morphine showed increased expression of exons I, IV, and IX of the BDNF gene, and had elevated levels of pro-BDNF and BDNF protein in their lumbar spinal cord. AMY, when co-administered with morphine from days 6 to 10, reversed morphine tolerance and adversely affected the morphine-induced expression of the BDNF gene at both levels of protein and mRNAs containing exons I, IV and IX. AMY alone increased levels of exons I and IV transcripts. Levels of pro-BDNF and BDNF proteins remained unchanged in the lumbar spinal cord of rats treated by AMY alone. These results suggest that i.t. AMY not only abolished morphine tolerance, but also reduced the morphine induced increase in the expression of both BDNF transcripts and protein in the lumbar spinal cord.
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Hoffmann AR, Saravanan MS, Lequin O, Killian JA, Khemtemourian L. A single mutation on the human amyloid polypeptide modulates fibril growth and affects the mechanism of amyloid-induced membrane damage. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1783-1792. [DOI: 10.1016/j.bbamem.2018.02.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 12/30/2022]
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14
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Topaz N, Mojib N, Chande AT, Kubanek J, Jordan IK. RampDB: a web application and database for the exploration and prediction of receptor activity modifying protein interactions. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2018; 2017:4107360. [PMID: 29220456 PMCID: PMC5737055 DOI: 10.1093/database/bax067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/07/2017] [Indexed: 12/28/2022]
Abstract
Receptor Activity Modifying Proteins (RAMPs) serve as accessory proteins that modulate the signaling activities of G-Protein Coupled Receptors (GPCRs). RAMPs function by interacting with the N-termini and transmembrane domains of GPCRs, and the receptor phenotypes of the resulting complexes are determined by the specific isoform of the interacting RAMPs. RAMPs were discovered in 1998, and since that time the number of known RAMP-GPCR interactions has steadily increased; RAMPs are now known to interact with nearly every member of the class ‘B’, Secretin receptor family of peptide-binding GPCRs as well as some members of the class ‘A’ and ‘C’ peptide-binding GPCRs. Given the steadily increasing number of known RAMP–GPCR interactions, phenotypes and functions, there is a pressing need for a central resource dedicated to their storage, prediction and dissemination. We have developed a web application and database—RampDB—with the goal of addressing this need. RampDB consists of a custom RAMP–GPCR–ligand database integrated with a search utility, which together facilitate the exploration and analysis of RAMP interactions. The RampDB search utility allows users to explore known RAMP interactions, or to predict novel interactions, via either protein sequence (bioinformatic) or ligand (chemoinformatic) queries. The underlying architecture of RampDB was designed using best database practices in order to enable rapid retrieval of search results, automated updates and the seamless incorporation of additional features. Database URL:http://rampdb.biology.gatech.edu
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Affiliation(s)
- Nadav Topaz
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA
| | - Nazia Mojib
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA
| | - Aroon T Chande
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA.,Applied Bioinformatics Laboratory, 950 Atlantic Drive, Atlanta, GA 30332, USA
| | - Julia Kubanek
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA.,School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Atlanta, GA 30332, USA.,Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 315 Ferst Dr NW, Atlanta, GA 30332, USA
| | - I King Jordan
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA.,Applied Bioinformatics Laboratory, 950 Atlantic Drive, Atlanta, GA 30332, USA.,PanAmerican Bioinformatics Institute, Cali, Valle del Cauca, Colombia
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15
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Routledge SJ, Ladds G, Poyner DR. The effects of RAMPs upon cell signalling. Mol Cell Endocrinol 2017; 449:12-20. [PMID: 28390954 DOI: 10.1016/j.mce.2017.03.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 02/01/2017] [Accepted: 03/24/2017] [Indexed: 12/29/2022]
Abstract
G protein-coupled receptors (GPCRs) play a vital role in signal transduction. It is now clear that numerous other molecules within the cell and at the cell surface interact with GPCRs to modulate their signalling properties. Receptor activity modifying proteins (RAMPs) are a group of single transmembrane domain proteins which have been predominantly demonstrated to interact with Family B GPCRs, but interactions with Family A and C receptors have recently begun to emerge. These interactions can influence cell surface expression, ligand binding preferences and G protein-coupling, thus modulating GPCR signal transduction. There is still a great deal of research to be conducted into the effects of RAMPs on GPCR signalling; their effects upon Family B GPCRs are still not fully documented, in addition to their potential interactions with Family A and C GPCRs. New interactions could have a significant impact on the development of therapeutics.
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Affiliation(s)
- Sarah J Routledge
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom.
| | - Graham Ladds
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom
| | - David R Poyner
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom
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16
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Singh Y, Gupta G, Shrivastava B, Dahiya R, Tiwari J, Ashwathanarayana M, Sharma RK, Agrawal M, Mishra A, Dua K. Calcitonin gene-related peptide (CGRP): A novel target for Alzheimer's disease. CNS Neurosci Ther 2017; 23:457-461. [PMID: 28417590 PMCID: PMC6492742 DOI: 10.1111/cns.12696] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/11/2017] [Accepted: 03/17/2017] [Indexed: 12/22/2022] Open
Abstract
Alzheimer's disease (AD) is leading cause of death among older characterized by neurofibrillary tangles, oxidative stress, progressive neuronal deficits, and increased levels of amyloid-β (Aβ) peptides. Cholinergic treatment could be the best suitable physiological therapy for AD. Calcitonin gene-related peptide (CGRP) is a thirty-seven-amino acid regulatory neuropeptide resulting from different merging of the CGRP gene, which also includes adrenomedullin, amylin, calcitonin, intermedin, and calcitonin receptor-stimulating peptide. It is a proof for a CGRP receptor within nucleus accumbens of brain that is different from either the CGRP1 or CGRP2 receptor in which it demonstrates similar high-affinity binding for salmon calcitonin, CGRP, and amylin, a possession which is not shared by any extra CGRP receptors. Binding of CGRP to its receptor increases activated cAMP-dependent pkA and PI3 kinase, resulting in N-terminal fragments that are shown to exert complex inhibitory as well facilitator actions on nAChRs. Fragments such as CGRP1-4, CGRP1-5, and CGRP1-6 rapidly as well as reversibly improve agonist sensitivity of nAChRs without straight stimulating those receptors and produce the Ca2+ -induced intracellular Ca2+ mobilization. Renin-angiotensin-aldosterone system (RAAS)-activated angiotensin-type (AT4) receptor is also beneficial in AD. It has been suggested that exogenous administration of CGRP inhibits infiltration of macrophages and expression of various inflammatory mediators such as NFkB, IL-1b, TNF-α, iNOS, matrix metalloproteinase (MMP)-9, and cell adhesion molecules like intercellular adhesion molecule (ICAM)-1 which attenuates consequence of inflammation in AD. Donepezil, a ChEI, inhibits acetylcholinesterase and produces angiogenesis and neurogenesis, in the dentate gyrus of the hippocampus of WT mice after donepezil administration. However, none of the results discovered in CGRP-knockout mice and WT mice exposed to practical denervation. Therefore, selective agonists of CGRP receptors may become the potential candidates for treatment of AD.
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Affiliation(s)
- Yogendra Singh
- School of PharmacyJaipur National UniversityJagatpuraJaipurIndia
| | - Gaurav Gupta
- School of PharmacyJaipur National UniversityJagatpuraJaipurIndia
- School of Medicine and Public HealthUniversity of NewcastleNewcastleNSWAustralia
| | | | - Rajiv Dahiya
- Laboratory of Peptide Research and DevelopmentSchool of Pharmacy, The University of the West IndiesSt. Augustine, Trinidad & TobagoWest Indies
| | - Juhi Tiwari
- School of PharmacyJaipur National UniversityJagatpuraJaipurIndia
| | | | | | - Mohit Agrawal
- School of pharmacySuresh Gyan Vihar UniversityJaipurIndia
| | - Anurag Mishra
- School of pharmacySuresh Gyan Vihar UniversityJaipurIndia
| | - Kamal Dua
- Discipline of PharmacyGraduate School of HealthUniversity of Technology SydneySydneyNSWAustralia
- School of Biomedical Sciences and PharmacyUniversity of NewcastleNewcastleNSWAustralia
- School of Pharmaceutical SciencesShoolini UniversitySolanHimachal PradeshIndia
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17
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Wu X, Wang K, Hua W, Li S, Liu X, Liu W, Song Y, Zhang Y, Shao Z, Yang C. Down-regulation of islet amyloid polypeptide expression induces death of human annulus fibrosus cells via mitochondrial and death receptor pathways. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1479-1491. [PMID: 28433710 DOI: 10.1016/j.bbadis.2017.04.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/10/2017] [Accepted: 04/17/2017] [Indexed: 01/07/2023]
Abstract
Islet amyloid polypeptide (IAPP) exerts its biological effects by participating in the regulation of glucose metabolism and cell apoptosis. The main goal of the present study was to investigate the expression of IAPP in degenerated intervertebral disc tissue and IAPP's modulation of extracellular matrix (ECM) catabolic and anabolic genes in human AF cells. We found that the expression of IAPP, the calcitonin receptor, and receptor activity modifying protein decreased considerably in AF cells during the progression of intervertebral disc degeneration (IDD). Meanwhile, transfection with pLV-siIAPP decreased the expression of IAPP and its receptors and reduced glucose uptake and the expression of aggrecan, Col2A1, and BG. Down-regulation of IAPP also induced a significant increase in reactive oxygen species generation in AF cells, along with a decrease in matrix metalloproteinases and an increase in the concentration of cellular Ca2+, ultimately leading to death. Further analysis revealed that siIAPP intervention promoted the release of cytochrome c from mitochondria, resulting in the activation of Caspase-3 and Caspase-9. In contrast, significantly decreased expression of Caspase-3 and Caspase-9 was observed in AF cells transfected with pLV-IAPP. The concentrations of Fas and FasL proteins were significantly decreased in AF cells transfected with PLV-IAPP, while activation of the Fas/FasL system and cell death were induced by siIAPP intervention. Mechanistically, AMPK/Akt-mTOR signaling pathways were involved. In conclusion, down-regulation of IAPP expression induces the death of human AF cells via mitochondrial and death receptor pathways, potentially offering a novel therapeutic target for the treatment of IDD.
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Affiliation(s)
- Xinghuo Wu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Kun Wang
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Wenbin Hua
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shuai Li
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xianzhe Liu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Wei Liu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Song
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yukun Zhang
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Zengwu Shao
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Cao Yang
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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18
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Whiting L, McCutcheon JE, Boyle CN, Roitman MF, Lutz TA. The area postrema (AP) and the parabrachial nucleus (PBN) are important sites for salmon calcitonin (sCT) to decrease evoked phasic dopamine release in the nucleus accumbens (NAc). Physiol Behav 2017; 176:9-16. [PMID: 28342771 DOI: 10.1016/j.physbeh.2017.03.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/16/2017] [Accepted: 03/17/2017] [Indexed: 12/26/2022]
Abstract
The pancreatic hormone amylin and its agonist salmon calcitonin (sCT) act via the area postrema (AP) and the lateral parabrachial nucleus (PBN) to reduce food intake. Investigations of amylin and sCT signaling in the ventral tegmental area (VTA) and nucleus accumbens (NAc) suggest that the eating inhibitory effect of amylin is, in part, mediated through the mesolimbic 'reward' pathway. Indeed, administration of the sCT directly to the VTA decreased phasic dopamine release (DA) in the NAc. However, it is not known if peripheral amylin modulates the mesolimbic system directly or whether this occurs via the AP and PBN. To determine whether and how peripheral amylin or sCT affect mesolimbic reward circuitry we utilized fast scan cyclic voltammetry under anesthesia to measure phasic DA release in the NAc evoked by electrical stimulation of the VTA in intact, AP lesioned and bilaterally PBN lesioned rats. Amylin (50μg/kg i.p.) did not change phasic DA responses compared to saline control rats. However, sCT (50μg/kg i.p.) decreased evoked DA release to VTA-stimulation over 1h compared to saline treated control rats. Further investigations determined that AP and bilateral PBN lesions abolished the ability of sCT to suppress evoked phasic DA responses to VTA-stimulation. These findings implicate the AP and the PBN as important sites for peripheral sCT to decrease evoked DA release in the NAc and suggest that these nuclei may influence hedonic and motivational processes to modulate food intake.
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Affiliation(s)
- Lynda Whiting
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - James E McCutcheon
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, England
| | - Christina N Boyle
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Mitchell F Roitman
- Department of Psychology, University of Illinois at Chicago, Chicago, IL, United States
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Centre of Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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19
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Wu X, Song Y, Liu W, Wang K, Gao Y, Li S, Duan Z, Shao Z, Yang S, Yang C. IAPP modulates cellular autophagy, apoptosis, and extracellular matrix metabolism in human intervertebral disc cells. Cell Death Discov 2017; 3:16107. [PMID: 28149534 PMCID: PMC5280875 DOI: 10.1038/cddiscovery.2016.107] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/04/2016] [Accepted: 12/13/2016] [Indexed: 12/14/2022] Open
Abstract
The pathogenic process of intervertebral disc degeneration (IDD) is characterized by imbalance in the extracellular matrix (ECM) metabolism. Nucleus pulposus (NP) cells have important roles in maintaining the proper structure and tissue homeostasis of disc ECM. These cells need adequate supply of glucose and oxygen. Islet amyloid polypeptide (IAPP) exerts its biological effects by regulating glucose metabolism. The purpose of this study was to investigate the expression of IAPP in degenerated IVD tissue, and IAPP modulation of ECM metabolism in human NP cells, especially the crosstalk mechanism between apoptosis and autophagy in these cells. We found that the expression of IAPP and Calcr-RAMP decreased considerably during IDD progression, along with the decrease in the expression of AG, BG, and Col2A1. Induction of IAPP in NP cells by transfection with pLV-IAPP enhanced the synthesis of aggrecan and Col2A1 and attenuated the expression of pro-inflammatory factors, tumor necrosis factor (TNF)-α, and interleukin (IL)-1. Upregulation of IAPP also affected the expression of the catabolic markers—matrix metalloproteinases (MMPs) 3, 9 and 13 and ADAMTS 4 and 5. Downregulation of IAPP by siRNA inhibited the expression of anabolic genes but increased the expression of catabolic genes and inflammatory factors. The expressions of autophagic and apoptotic markers in NP cells transfected with pLV-IAPP were upregulated, including BECLIN1, ATG5, ATG7, LC3 II/I and Bcl-2, while significantly increase in the expression of Bax and Caspase-3 in NP cells transfected with pLV-siIAPP. Mechanistically, PI3K/AKT-mTOR and p38/JNK MAPK signal pathways were involved. We propose that IAPP might play a pivotal role in the development of IDD, by regulating ECM metabolism and controlling the crosstalk between apoptosis and autophagy in NP, thus potentially offering a novel therapeutic approach to the treatment of IDD.
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Affiliation(s)
- Xinghuo Wu
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Yu Song
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Wei Liu
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Kun Wang
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Yong Gao
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Shuai Li
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Zhenfeng Duan
- Department of Orthopaedic Surgery, Massachusetts General Hospital and Harvard Medical School , Boston, MA, USA
| | - Zengwu Shao
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Shuhua Yang
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
| | - Cao Yang
- Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan 430022, China
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20
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Johnson MD, Bouret SG, Dunn-Meynell AA, Boyle CN, Lutz TA, Levin BE. Early postnatal amylin treatment enhances hypothalamic leptin signaling and neural development in the selectively bred diet-induced obese rat. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1032-R1044. [PMID: 27629888 PMCID: PMC5256974 DOI: 10.1152/ajpregu.00326.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/02/2016] [Accepted: 09/02/2016] [Indexed: 12/25/2022]
Abstract
Selectively bred diet-induced obese (DIO) rats become obese on a high-fat diet and are leptin resistant before becoming obese. Compared with diet-resistant (DR) neonates, DIO neonates have impaired leptin-dependent arcuate (ARC) neuropeptide Y/agouti-related peptide (NPY/AgRP) and α-melanocyte-stimulating hormone (α-MSH; from proopiomelanocortin (POMC) neurons) axon outgrowth to the paraventricular nucleus (PVN). Using phosphorylation of STAT3 (pSTAT3) as a surrogate, we show that reduced DIO ARC leptin signaling develops by postnatal day 7 (P7) and is reduced within POMC but not NPY/AgRP neurons. Since amylin increases leptin signaling in adult rats, we treated DIO neonates with amylin during postnatal hypothalamic development and assessed leptin signaling, leptin-dependent ARC-PVN pathway development, and metabolic changes. DIO neonates treated with amylin from P0-6 and from P0-16 increased ARC leptin signaling and both AgRP and α-MSH ARC-PVN pathway development, but increased only POMC neuron number. Despite ARC-PVN pathway correction, P0-16 amylin-induced reductions in body weight did not persist beyond treatment cessation. Since amylin enhances adult DIO ARC signaling via an IL-6-dependent mechanism, we assessed ARC-PVN pathway competency in IL-6 knockout mice and found that the AgRP, but not the α-MSH, ARC-PVN pathway was reduced. These results suggest that both leptin and amylin are important neurotrophic factors for the postnatal development of the ARC-PVN pathway. Amylin might act as a direct neurotrophic factor in DIO rats to enhance both the number of POMC neurons and their α-MSH ARC-PVN pathway development. This suggests important and selective roles for amylin during ARC hypothalamic development.
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Affiliation(s)
- Miranda D Johnson
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sebastien G Bouret
- The Saban Research Institute, Developmental Neuroscience Program, Children's Hospital Los Angeles, University of Southern California, Los Angeles, California.,INSERM, Jean-Pierre Aubert Research Center, Lille, France
| | | | - Christina N Boyle
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; and
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; and
| | - Barry E Levin
- Department of Neurology, Rutgers New Jersey Medical School, Newark, New Jersey
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21
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Khoshdel Z, Takhshid MA, Owji AA. Effects of intrathecal amylin on formalin-induced nociception and on cAMP accumulation in the rat embryonic spinal cells. Neuropeptides 2016; 57:95-100. [PMID: 26778650 DOI: 10.1016/j.npep.2015.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 12/23/2015] [Accepted: 12/26/2015] [Indexed: 11/17/2022]
Abstract
Amylin (AMY) is a member of calcitonin family of peptides. In this study, the effects of intrathecal (i.t) injection of AMY on the inflammatory pain and on the cAMP accumulation in the rat spinal cells were investigated. By using AMY receptor antagonists, we also studied the pharmacology of AMY receptors in the spinal cells. Formalin model of inflammatory pain was induced by intraplantar injection of formalin. AMY (0.06250-2500pmol/rat) was administrated i.t 15min before the injection of formalin. Antagonists were injected i.t 10min before the injection of AMY and/or morphine. AMY reduced formalin-induced pain in a dose dependent mode. This effect was inhibited by the potent AMY antagonist, AC187 but not CGRP8-37. rAMY8-37, most commonly reported as a weak AMY antagonist, showed to be equally or more potent than AC187 in antagonizing the above effects. The opioid antagonist, naloxone, had no significant effects on AMY antinociceptive effects. Primary dissociated cell culture was used to investigate the effect of AMY on cAMP production and to characterize AMY receptors in the spinal cells. AMY moderately increases cAMP accumulation in the spinal cells with an EC50 value of 74.62nM. This effect was not affected by CGRP8-37 but was inhibited by AC187 and rAMY8-37 with pA2 values of 7.94 and 7.87 respectively. In conclusion, effects of AMY in reducing formalin induced pain and on the cAMP accumulation by spinal cells are mediated through undefined receptors.
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Affiliation(s)
- Zahra Khoshdel
- Department of Biochemistry, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ali Takhshid
- Diagnostic Laboratory Sciences and Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
| | - Ali Akbar Owji
- Research Center for Psychiatry and Behavioral Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
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22
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Liberini CG, Boyle CN, Cifani C, Venniro M, Hope BT, Lutz TA. Amylin receptor components and the leptin receptor are co-expressed in single rat area postrema neurons. Eur J Neurosci 2016; 43:653-61. [PMID: 26750109 PMCID: PMC10704335 DOI: 10.1111/ejn.13163] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/17/2015] [Accepted: 12/22/2015] [Indexed: 12/16/2023]
Abstract
Amylin is a pancreatic β-cell hormone that acts as a satiating signal to inhibit food intake by binding to amylin receptors (AMYs) and activating a specific neuronal population in the area postrema (AP). AMYs are heterodimers that include a calcitonin receptor (CTR) subunit [CTR isoform a or b (CTRa or CTRb)] and a member of the receptor activity-modifying proteins (RAMPs). Here, we used single-cell quantitative polymerase chain reaction to assess co-expression of AMY subunits in AP neurons from rats that were injected with amylin or vehicle. Because amylin interacts synergistically with the adipokine leptin to reduce body weight, we also assessed the co-expression of AMY and the leptin receptor isoform b (LepRb) in amylin-activated AP neurons. Single cells were collected from Wistar rats and from transgenic Fos-GFP rats that express green fluorescent protein (GFP) under the control of the Fos promoter. We found that the mRNAs of CTRa, RAMP1, RAMP2 and RAMP3 were all co-expressed in single AP neurons. Moreover, most of the CTRa+ cells co-expressed more than one of the RAMPs. Amylin down-regulated RAMP1 and RAMP3 but not CTR mRNAs in AMY+ neurons, suggesting a possible negative feedback mechanism of amylin at its own primary receptors. Interestingly, amylin up-regulated RAMP2 mRNA. We also found that a high percentage of single cells that co-expressed all components of a functional AMY expressed LepRb mRNA. Thus, single AP cells expressed both AMY and LepRb, which formed a population of first-order neurons that presumably can be directly activated by amylin and, at least in part, also by leptin.
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Affiliation(s)
- Claudia G. Liberini
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), Zurich, Switzerland
- Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Zurich Centre for Clinical Studies, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Christina Neuner Boyle
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), Zurich, Switzerland
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, Italy
- Intramural Research Program, National Institutes of Health/National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Marco Venniro
- Intramural Research Program, National Institutes of Health/National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Bruce T. Hope
- Intramural Research Program, National Institutes of Health/National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Thomas A. Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), Zurich, Switzerland
- Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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23
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Dunn-Meynell AA, Le Foll C, Johnson MD, Lutz TA, Hayes MR, Levin BE. Endogenous VMH amylin signaling is required for full leptin signaling and protection from diet-induced obesity. Am J Physiol Regul Integr Comp Physiol 2016; 310:R355-65. [PMID: 26676252 PMCID: PMC4868368 DOI: 10.1152/ajpregu.00462.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 12/10/2015] [Indexed: 12/29/2022]
Abstract
Amylin enhances arcuate (ARC) and ventromedial (VMN) hypothalamic nuclei leptin signaling and synergistically reduces food intake and body weight in selectively bred diet-induced obese (DIO) rats. Since DIO (125)I-amylin dorsomedial nucleus-dorsomedial VMN binding was reduced, we postulated that this contributed to DIO ventromedial hypothalamus (VMH) leptin resistance, and that impairing VMH (ARC + VMN) calcitonin receptor (CTR)-mediated signaling by injecting adeno-associated virus (AAV) expressing a short hairpin portion of the CTR mRNA would predispose diet-resistant (DR) rats to obesity on high-fat (45%) diet (HFD). Depleting VMH CTR by 80-90% in 4-wk-old male DR rats reduced their ARC and VMN (125)I-labeled leptin binding by 57 and 51%, respectively, and VMN leptin-induced phospho-signal transducer and activator of transcription 3-positive neurons by 59% vs. AAV control rats. After 6 wk on chow, VMH CTR-depleted DR rats ate and gained the equivalent amount of food and weight but had 18% heavier fat pads (relative to carcass weight), 144% higher leptin levels, and were insulin resistant compared with control AAV DR rats. After 6 wk more on HFD, VMH CTR-depleted DR rats ate the same amount but gained 28% more weight, had 60% more carcass fat, 254% higher leptin levels, and 132% higher insulin areas under the curve during an oral glucose tolerance test than control DR rats. Therefore, impairing endogenous VMH CTR-mediated signaling reduced leptin signaling and caused DR rats to become more obese and insulin resistant, both on chow and HFD. These results suggest that endogenous VMH amylin signaling is required for full leptin signaling and protection from HFD-induced obesity.
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Affiliation(s)
| | - Christelle Le Foll
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Miranda D Johnson
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Matthew R Hayes
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Barry E Levin
- Neurology Service, Veterans Administration Medical Center, East Orange, New Jersey; Department of Neurology, Rutgers, New Jersey Medical School, Newark, New Jersey
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Visa M, Alcarraz‐Vizán G, Montane J, Cadavez L, Castaño C, Villanueva‐Peñacarrillo ML, Servitja J, Novials A. Islet amyloid polypeptide exerts a novel autocrine action in β‐cell signaling and proliferation. FASEB J 2015; 29:2970-9. [DOI: 10.1096/fj.15-270553] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/04/2015] [Indexed: 01/31/2023]
Affiliation(s)
- Montse Visa
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Gema Alcarraz‐Vizán
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Joel Montane
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Lisa Cadavez
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Carlos Castaño
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - María Luisa Villanueva‐Peñacarrillo
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
- Department of Metabolism, Nutrition and HormonesInstituto de Investigación Sanitaria de la Fundación Jiménez DíazMadridSpain
| | - Joan‐Marc Servitja
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Anna Novials
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
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25
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van der Westhuizen ET, Valant C, Sexton PM, Christopoulos A. Endogenous Allosteric Modulators of G Protein–Coupled Receptors. J Pharmacol Exp Ther 2015; 353:246-60. [DOI: 10.1124/jpet.114.221606] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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26
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Martins R, Vieira FA, Power DM. Calcitonin receptor family evolution and fishing for function using in silico promoter analysis. Gen Comp Endocrinol 2014; 209:61-73. [PMID: 24815885 DOI: 10.1016/j.ygcen.2014.04.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/27/2014] [Indexed: 11/30/2022]
Abstract
In the present study the calcitonin receptor (CTR) sub-family of family B G-protein coupled receptors (GPCRs) in teleosts is evaluated and put in the context of the families overall evolution from echinodermates to vertebrates. Echinodermates, hemichordates, cephalochordates and tunicates have a single gene that encodes a receptor that bears similarity to the vertebrate calcitonin receptor (CTR) and calcitonin-like receptor (CTR/CLR). In tetrapods one gene encodes the calcitonin receptor (CALCR) and another gene the calcitonin receptor-like receptor (CALCRL). The evolution of CALCR has been under strong conservative pressure and a single copy is also found in fishes and high conservation of gene organisation and synteny exits from teleosts to human. A teleost specific CTR innovation that occurred after their divergence from holostei is the presence of several HBDs in the N-terminus. CALCRL had a different evolutionary trajectory from CALCR and although a single gene copy is present in tetrapods the sarcopterygii fish, the coelacanth, has 1 copy of CALCRL but also a fish specific form CALCRL3. The ray-finned fish, the spotted gar, has 1 copy of CALCRL and 1 of CALCRL3 but the teleost specific whole genome duplication has resulted in a CALCRL1 and CALCRL2 in addition to the fish specific CALCRL3. Strong conservation of CALCRL gene structure exists from human to fish. Promoter analysis in silico reveals that the duplicated CALCRL genes in the teleosts, zebrafish, takifugu, tetraodon and medaka, have divergent promoters and different putative co-regulated gene partners suggesting their function is different.
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Affiliation(s)
- Rute Martins
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Flobela A Vieira
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Deborah M Power
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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27
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Kowalczyk R, Brimble MA, Tomabechi Y, Fairbanks AJ, Fletcher M, Hay DL. Convergent chemoenzymatic synthesis of a library of glycosylated analogues of pramlintide: structure-activity relationships for amylin receptor agonism. Org Biomol Chem 2014; 12:8142-51. [PMID: 25030939 DOI: 10.1039/c4ob01208a] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pramlintide (Symlin®), a synthetic analogue of the naturally occurring pancreatic hormone amylin, is currently used with insulin in adjunctive therapy for type 1 and type 2 diabetes mellitus. Herein we report a systematic study into the effect that N-glycosylation of pramlintide has on activation of amylin receptors. A highly efficient convergent synthetic route, involving a combination of solid phase peptide synthesis and enzymatic glycosylation, delivered a library of N-glycosylated variants of pramlintide bearing either GlcNAc, the core N-glycan pentasaccharide [Man3(GlcNAc)2] or a complex biantennary glycan [(NeuAcGalGlcNAcMan)2Man(GlcNAc)2] at each of its six asparagine residues. The majority of glycosylated versions of pramlintide were potent receptor agonists, suggesting that N-glycosylation may be used as a tool to optimise the pharmacokinetic properties of pramlintide and so deliver improved therapeutic agents for the treatment of diabetes and obesity.
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Affiliation(s)
- Renata Kowalczyk
- The School of Chemical Sciences, University of Auckland, 23 Symonds St, Auckland 1010, New Zealand.
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28
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Wang J, Xiao R. G protein-coupled receptors in energy homeostasis. SCIENCE CHINA-LIFE SCIENCES 2014; 57:672-80. [PMID: 24969703 DOI: 10.1007/s11427-014-4694-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 06/13/2014] [Indexed: 12/25/2022]
Abstract
G-protein coupled receptors (GPCRs) compromise the largest membrane protein superfamily which play vital roles in physiological and pathophysiological processes including energy homeostasis. Moreover, they also represent the up-to-date most successful drug target. The gut hormone GPCRs, such as glucagon receptor and GLP-1 receptor, have been intensively studied for their roles in metabolism and respective drugs have developed for the treatment of metabolic diseases such as type 2 diabetes (T2D). Along with the advances of biomedical research, more GPCRs have been found to play important roles in the regulation of energy homeostasis from nutrient sensing, appetite control to glucose and fatty acid metabolism with various mechanisms. The investigation of their biological functions will not only improve our understanding of how our body keeps the balance of energy intake and expenditure, but also highlight the possible drug targets for the treatment of metabolic diseases. The present review summarizes GPCRs involved in the energy control with special emphasis on their pathophysiological roles in metabolic diseases and hopefully triggers more intensive and systematic investigations in the field so that a comprehensive network control of energy homeostasis will be revealed, and better drugs will be developed in the foreseeable future.
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Affiliation(s)
- Jue Wang
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China,
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29
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Mietlicki-Baase EG, Hayes MR. Amylin activates distributed CNS nuclei to control energy balance. Physiol Behav 2014; 136:39-46. [PMID: 24480072 DOI: 10.1016/j.physbeh.2014.01.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 01/13/2014] [Accepted: 01/16/2014] [Indexed: 01/25/2023]
Abstract
Amylin is a pancreas-derived neuropeptide that acts in the central nervous system (CNS) to reduce food intake. Much of the literature describing the anorectic effects of amylin are focused on amylin's actions in the area postrema, a hindbrain circumventricular structure. Although the area postrema is certainly an important site that mediates the intake-suppressive effects of amylin, several pieces of evidence indicate that amylin may also promote negative energy balance through action in additional CNS nuclei, including hypothalamic and mesolimbic structures. Therefore, this review highlights the distributed neural network mediating the feeding effects of amylin signaling with special attention being devoted to the recent discovery that the ventral tegmental area is physiologically relevant for amylin-mediated control of feeding. The production of amylin by alternative, extra-pancreatic sources and its potential relevance to food intake regulation is also considered. Finally, the utility of amylin and amylin-like compounds as a component of combination pharmacotherapies for the treatment of obesity is discussed.
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Affiliation(s)
- Elizabeth G Mietlicki-Baase
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Matthew R Hayes
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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30
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Fernandes-Santos C, Zhang Z, Morgan DA, Guo DF, Russo AF, Rahmouni K. Amylin acts in the central nervous system to increase sympathetic nerve activity. Endocrinology 2013; 154:2481-8. [PMID: 23645151 PMCID: PMC3689285 DOI: 10.1210/en.2012-2172] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The pancreatic hormone amylin acts in the central nervous system (CNS) to decrease food intake and body weight. We hypothesized that amylin action in the CNS promotes energy expenditure by increasing the activity of the sympathetic nervous system. In mice, ip administration of amylin significantly increased c-Fos immunoreactivity in hypothalamic and brainstem nuclei. In addition, mice treated with intracerebroventricular (icv) amylin (0.1 and 0.2 nmol) exhibited a dose-related decrease in food intake and body weight, measured 4 and 24 hours after treatment. The icv injection of amylin also increased body temperature in mice. Using direct multifiber sympathetic nerve recording, we found that icv amylin elicited a significant and dose-dependent increase in sympathetic nerve activity (SNA) subserving thermogenic brown adipose tissue (BAT). Of note, icv injection of amylin also evoked a significant and dose-related increase in lumbar and renal SNA. Importantly, icv pretreatment with the amylin receptor antagonist AC187 (20 nmol) abolished the BAT SNA response induced by icv amylin, indicating that the sympathetic effects of amylin are receptor-mediated. Conversely, icv amylin-induced BAT SNA response was enhanced in mice overexpressing the amylin receptor subunit, RAMP1 (receptor-activity modifying protein 1), in the CNS. Our data demonstrate that CNS action of amylin regulates sympathetic nerve outflow to peripheral tissues involved in energy balance and cardiovascular function.
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Affiliation(s)
- Caroline Fernandes-Santos
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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31
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Feigh M, Andreassen KV, Neutzsky-Wulff AV, Petersen ST, Hansen C, Bay-Jensen AC, Henriksen JE, Beck-Nielsen H, Christiansen C, Henriksen K, Karsdal MA. Oral salmon calcitonin attenuates hyperglycaemia and preserves pancreatic beta-cell area and function in Zucker diabetic fatty rats. Br J Pharmacol 2013; 167:151-63. [PMID: 22506938 DOI: 10.1111/j.1476-5381.2012.01979.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND AND PURPOSE Oral salmon calcitonin (sCT), a dual-action amylin and calcitonin receptor agonist, improved glucose homeostasis in diet-induced obese rats. Here, we have evaluated the anti-diabetic efficacy of oral sCT using parameters of glycaemic control and beta-cell morphology in male Zucker diabetic fatty (ZDF) rats, a model of type 2 diabetes. EXPERIMENTAL APPROACH Male ZDF rats were treated with oral sCT (0.5, 1.0 or 2 mg·kg(-1) ) or oral vehicle twice daily from age 8 to 18 weeks. Zucker lean rats served as control group. Fasting and non-fasted blood glucose, glycosylated haemoglobin (HbA1c) and levels of pancreas and incretin hormones were determined. Oral glucose tolerance test and i.p. glucose tolerance test were compared, and beta-cell area and function were evaluated. KEY RESULTS Oral sCT treatment dose-dependently attenuated fasting and non-fasted hyperglycaemia during the intervention period. At the end of the study period, oral sCT treatment by dose decreased diabetic hyperglycaemia by ∼9 mM and reduced HbA1c levels by 1.7%. Furthermore, a pronounced reduction in glucose excursions was dose-dependently observed for oral sCT treatment during oral glucose tolerance test. In addition, oral sCT treatment sustained hyperinsulinaemia and attenuated hyperglucagonaemia and hypersecretion of total glucagon-like peptide-1 predominantly in the basal state. Lastly, oral sCT treatment dose-dependently improved pancreatic beta-cell function and beta-cell area at study end. CONCLUSIONS AND IMPLICATIONS Oral sCT attenuated diabetic hyperglycaemia in male ZDF rats by improving postprandial glycaemic control, exerting an insulinotropic and glucagonostatic action in the basal state and by preserving pancreatic beta-cell function and beta-cell area.
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Affiliation(s)
- M Feigh
- Nordic Bioscience, Herlev, Denmark Diabetes Research Centre, Department of Endocrinology M, Odense University Hospital, Odense, Denmark.
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Sherafat-Kazemzadeh R, Yanovski SZ, Yanovski JA. Pharmacotherapy for childhood obesity: present and future prospects. Int J Obes (Lond) 2013; 37:1-15. [PMID: 22929210 PMCID: PMC3522799 DOI: 10.1038/ijo.2012.144] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Pediatric obesity is a serious medical condition associated with significant comorbidities during childhood and adulthood. Lifestyle modifications are essential for treating children with obesity, yet many have insufficient response to improve health with behavioral approaches alone. This review summarizes the relatively sparse data on pharmacotherapy for pediatric obesity and presents information on obesity medications in development. Most previously studied medications demonstrated, at best, modest effects on body weight and obesity-related conditions. It is to be hoped that the future will bring new drugs targeting specific obesity phenotypes that will allow clinicians to use etiology-specific, and therefore more effective, anti-obesity therapies.
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Affiliation(s)
- Roya Sherafat-Kazemzadeh
- Section on Growth and Obesity, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development
| | - Susan Z. Yanovski
- Section on Growth and Obesity, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development
- Division of Digestive Diseases and Nutrition, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health
| | - Jack A. Yanovski
- Section on Growth and Obesity, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development
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33
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Thulé PM. Mechanisms of current therapies for diabetes mellitus type 2. ADVANCES IN PHYSIOLOGY EDUCATION 2012; 36:275-83. [PMID: 23209008 PMCID: PMC3776431 DOI: 10.1152/advan.00094.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 09/21/2012] [Indexed: 06/12/2023]
Abstract
The array of medications available for the treatment of hyperglycemia has increased rapidly in the previous decade, and recent investigations have clarified novel mechanisms underlying the antihyperglycemic efficacy of these drugs. This article reviews the mechanisms of action for medications currently approved to treat diabetes mellitus in the United States, with the exception of insulin and its analogs. Finally, it attempts to integrate these mechanisms into the schema of pathophysiological factors that combine to produce hyperglycemia in patients with diabetes mellitus.
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Affiliation(s)
- Peter M Thulé
- Emory University School of Medicine, Decatur, Georgia, USA.
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34
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Montane J, Klimek-Abercrombie A, Potter KJ, Westwell-Roper C, Bruce Verchere C. Metabolic stress, IAPP and islet amyloid. Diabetes Obes Metab 2012; 14 Suppl 3:68-77. [PMID: 22928566 DOI: 10.1111/j.1463-1326.2012.01657.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Amyloid forms within pancreatic islets in type 2 diabetes from aggregates of the β-cell peptide islet amyloid polypeptide (IAPP). These aggregates are toxic to β-cells, inducing β-cell death and dysfunction, as well as inciting islet inflammation. The β-cell is subject to a number of other stressors, including insulin resistance and hyperglycaemia, that may contribute to amyloid formation by increasing IAPP production by the β-cell. β-Cell dysfunction, evident as impaired glucose-stimulated insulin secretion and defective prohormone processing and exacerbated by metabolic stress, is also a likely prerequisite for islet amyloid formation to occur in type 2 diabetes. Islet transplants in patients with type 1 diabetes face similar stressors, and are subject to rapid amyloid formation and impaired proinsulin processing associated with progressive loss of β-cell function and mass. Declining β-cell mass is predicted to increase metabolic demand on remaining β-cells, promoting a feed-forward cycle of β-cell decline.
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Affiliation(s)
- J Montane
- Department of Pathology & Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
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35
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β-Amyloid protein (Aβ) and human amylin regulation of apoptotic genes occurs through the amylin receptor. Apoptosis 2012; 17:37-47. [PMID: 21947943 DOI: 10.1007/s10495-011-0656-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Deposition of amyloid-beta (Aβ) protein, a 39-43 amino acid peptide, in the brain is a major pathological feature of Alzheimer's disease (AD). We have previously provided evidence that in primary cultures of rat basal forebrain and human fetal neurons (HFNs), neurotoxic effects of oligomeric Aβ are expressed through the amylin receptor. In this study, we utilized RT-PCR arrays to compare RNA expression levels of 84 markers for pro and anti- apoptotic signalling pathways following exposure of HFNs to either Aβ(1-42) (20 μM) or human amylin (2 μM). Oligomeric Aβ(1-42) or human amylin was applied to HFNs alone or after pre-treatment of cultures with the amylin receptor antagonist, AC253. Changes in RNA levels were then quantified and compared to each other in order to identify increases or decreases in gene expression of apoptotic markers. Applications of Aβ(1-42) or human amylin, but not the inactive inverse sequence Aβ(42-1) or rat amylin, resulted in a time-dependent marked increase in mediators of apoptosis including a 10- to 30-fold elevations in caspases 3, 6, 9, BID and XIAP levels. Amylin receptor antagonists, AC253 (10 μM) or AC187 (10 μM), significantly attenuated the induction of several pro-apoptotic mediators up-regulated following exposure to Aβ(1-42) or human amylin and increased the expression of several anti-apoptotic markers. These data allow us to identify key elements in the Aβ-induced apoptosis that are blocked by antagonism of the amylin receptor and further support the potential for amylin receptor blockade as a potential therapeutic avenue in AD.
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36
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Cao P, Raleigh DP. Analysis of the inhibition and remodeling of islet amyloid polypeptide amyloid fibers by flavanols. Biochemistry 2012; 51:2670-83. [PMID: 22409724 DOI: 10.1021/bi2015162] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Islet amyloid polypeptide (IAPP, amylin) is responsible for amyloid formation in type 2 diabetes and in transplanted islets. The flavanol (-)-epigallocatechin-3-gallate [EGCG; (2R,3R)-5,7-dihydroxy-2-(3,4,5-trihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3-yl 3,4,5-trihydroxybenzoate] is an effective inhibitor of amyloid formation by IAPP; however, the interactions required for the inhibition of IAPP amyloid formation and for the remodeling of amyloid fibers are not known. A range of features have been proposed to be critical for EGCG protein interactions, including interactions with aromatic residues, interactions with amino groups, or sulfhydryls. Using a set of IAPP analogues, we show that none of these are required. Studies in which EGCG is added to the lag phase of amyloid formation shows that it interacts with intermediates as well as with monomers and amyloid. The features of EGCG required for effective inhibition were examined. The stereoisomer of EGCG, (-)-gallocatechin gallate (GCG), is an effective inhibitor, although less so than EGCG. Removing the gallate ester moiety leads to EGC which is a less effective inhibitor. Removing only the 3-hydroxyl group of the trihydroxyphenyl ring leads to a compound that has more pronounced effects on the lag phase than EGC but is less effective at reducing the amount of amyloid. Elimination of both the 3-hydroxy group and the gallate ester results in loss of activity. EGCG remodels IAPP amyloid fibers but does not fully resolubilize them to unstructured monomers, and the remodeling is not the reverse of amyloid assembly. The ability of the compounds to remodel IAPP amyloid closely follows their relative ability to inhibit amyloid formation.
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Affiliation(s)
- Ping Cao
- Department of Chemistry, Stony Brook University, Nicolls Road Stony Brook, New York 11794-3400, United States
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37
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Noor H, Cao P, Raleigh DP. Morin hydrate inhibits amyloid formation by islet amyloid polypeptide and disaggregates amyloid fibers. Protein Sci 2012; 21:373-82. [PMID: 22238175 DOI: 10.1002/pro.2023] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 12/19/2011] [Indexed: 01/09/2023]
Abstract
The polypeptide hormone Islet Amyloid Polypeptide (IAPP, amylin) is responsible for islet amyloid formation in type-2 diabetes and in islet cell transplants, where it may contribute to graft failure. Human IAPP is extremely amyloidogenic and fewer inhibitors of IAPP amyloid formation have been reported than for the Alzheimer's Aβ peptide or for α-synuclein. The ability of a set of hydroxyflavones to inhibit IAPP amyloid formation was tested. Fluorescence detected thioflavin-T-binding assays are the most popular methods for measuring the kinetics of amyloid formation and for screening potential inhibitors; however, we show that they can lead to false positives with hydroxyflavones. Several of the compounds inhibit thioflavin-T fluorescence, but not amyloid formation; a result which highlights the hazards of relying solely on thioflavin-T assays to screen potential inhibitors. Transmission electron microscopy (TEM) and right-angle light scattering show that Morin hydrate (2',3,4',5,7-Pentahydroxyflavone) inhibits amyloid formation by human IAPP and disaggregates preformed IAPP amyloid fibers. In contrast, Myricetin, Kaempferol, and Quercetin, which differ only in hydroxyl groups on the B-ring, are not effective inhibitors. Morin hydrate represents a new type of IAPP amyloid inhibitor and the results with the other compounds highlight the importance of the substitution pattern on the B-ring.
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Affiliation(s)
- Harris Noor
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA
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Dobolyi A. Novel potential regulators of maternal adaptations during lactation: tuberoinfundibular peptide 39 and amylin. J Neuroendocrinol 2011; 23:1002-8. [PMID: 21418340 DOI: 10.1111/j.1365-2826.2011.02127.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Maternal adaptations during lactation include milk synthesis and ejection, the appearance of maternal behaviours, reduced stress response, suppression of the ovarian cycle, and increased food and fluid intake. Several recently identified neuropeptides may participate in these adaptations, and we focus on two of them in the present study: tuberoinfundibular peptide of 39 residues (TIP39) and amylin. TIP39 is the ligand of the parathyroid hormone 2 receptor (PTH2 receptor) is induced in the posterior intralaminar complex of the thalamus (PIL) during lactation. TIP39 neurones in the PIL are activated in mother rats in response to pup exposure and project to preoptic, periventricular, paraventricular, arcuate and dorsomedial regions of the hypothalamus. Furthermore, an antagonist of the PTH2 receptor reduced suckling induced prolactin release. On the basis of their projections, TIP39 neurones might interact with additional neurones involved in maternal adaptations, including kisspeptin neurones participating in the control of gonadotrophin-releasing hormone function. TIP39 fibres might also interact with amylin, a peptide that we recently identified to appear in the preoptic area of rat dams. On the basis of its distribution, preoptic amylin could play a role in the control of maternal behaviours. We hypothesise that TIP39 neurones mediate the effects of suckling on different hypothalamic systems to affect maternal adaptations.
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Affiliation(s)
- A Dobolyi
- Department of Anatomy, Histology and Embryology, Neuromorphological and Neuroendocrine Research Laboratory, Semmelweis University and Hungarian Academy of Sciences, Budapest, Hungary.
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39
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Szabó ÉR, Cservenák M, Dobolyi A. Amylin is a novel neuropeptide with potential maternal functions in the rat. FASEB J 2011; 26:272-81. [DOI: 10.1096/fj.11-191841] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Éva Rebeka Szabó
- Neuromorphological and Neuroendocrine Research Laboratory, Department of Anatomy, Histology, and EmbryologySemmelweis University and the Hungarian Academy of Sciences Budapest Hungary
| | - Melinda Cservenák
- Neuromorphological and Neuroendocrine Research Laboratory, Department of Anatomy, Histology, and EmbryologySemmelweis University and the Hungarian Academy of Sciences Budapest Hungary
| | - Arpad Dobolyi
- Neuromorphological and Neuroendocrine Research Laboratory, Department of Anatomy, Histology, and EmbryologySemmelweis University and the Hungarian Academy of Sciences Budapest Hungary
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Adeghate E, Kalász H. Amylin analogues in the treatment of diabetes mellitus: medicinal chemistry and structural basis of its function. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2011; 5:78-81. [PMID: 21966328 PMCID: PMC3174573 DOI: 10.2174/1874104501105010078] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/20/2011] [Accepted: 02/25/2011] [Indexed: 12/17/2022]
Abstract
Amylin, (islet amyloid polypeptide) or diabetes-associated peptide is co-secreted with insulin in the islet of Langerhans of diabetic patients in approximately 1:100, amylin-insulin ratio. The soluble form of amylin, an analogue of amylin, is used as a supplement to insulin in the treatment of type 1 diabetes. Co-administration of amylin analogue with insulin to patients with type 1 diabetes induced a larger reduction in proprandial hyperglycemia, with a concomitant reduction in the level of glucagon when compared to insulin monotherapy. The actions of amylin analogues appear to be synergistic to insulin, with which it is co-released from insulin-producing beta cells after a meal. Amylin analogues such as pramlintide has been shown to significantly reduce body weight, HbA1c values and even the dosage of insulin. A moderate weight loss can also be achieved in obese patients with or without diabetes. A major side effect of some amylin analogues includes nausea and excitation of the area postrema. This review examines the medicinal chemistry of amylin and its analogues and their effects.
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Affiliation(s)
- Ernest Adeghate
- Department of Anatomy, Faculty of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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Zhang Z, Liu X, Morgan DA, Kuburas A, Thedens DR, Russo AF, Rahmouni K. Neuronal receptor activity-modifying protein 1 promotes energy expenditure in mice. Diabetes 2011; 60:1063-71. [PMID: 21357463 PMCID: PMC3064080 DOI: 10.2337/db10-0692] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Receptor activity-modifying proteins (RAMPs) 1, 2, and 3 are unusual accessory proteins that dictate the binding specificity of two G protein-coupled receptors involved in energy homeostasis: calcitonin gene-related peptide (CGRP) and amylin receptors. These proteins are expressed throughout the central nervous system (CNS), including in the brain regions involved in the regulation of energy homeostasis, but the significance of CNS RAMPs in the control of energy balance remains unknown. RESEARCH DESIGN AND METHODS To examine the functional significance of modulating neuronal RAMP1, we assessed the effect of overexpressing human RAMP1 (hRAMP1) in the CNS on body energy balance. RESULTS Nestin/hRAMP1 transgenic mice have a remarkably decreased body weight associated with reduced fat mass and circulating leptin levels. The transgenic mice exhibited higher energy expenditure as indicated by increased oxygen consumption, body temperature, and sympathetic tone subserving brown adipose tissue (BAT). Consistent with this, the nestin/hRAMP1 transgenic mice had elevated BAT mRNA levels of peroxisome proliferator-activated receptor γ coactivator 1α and uncoupling protein 1 and 3, and these changes can be reversed by chronic blockade of sympathetic nervous system signaling. Furthermore, metabolic response to amylin was enhanced in the nestin/hRAMP1 mice whereas the response to CGRP was blunted, possibly the result of higher expression of CGRP in the CNS. CONCLUSIONS These data demonstrate that CNS RAMP1 plays a pivotal role in the regulation of energy homeostasis by promoting energy expenditure.
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Affiliation(s)
- Zhongming Zhang
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Xuebo Liu
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Donald A. Morgan
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Adisa Kuburas
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Daniel R. Thedens
- Department of Radiology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Andrew F. Russo
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Kamal Rahmouni
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Corresponding author: Kamal Rahmouni,
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Abstract
Seven mammalian purinergic receptor subunits, denoted P2X1-P2X7, and several spliced forms of these subunits have been cloned. When heterologously expressed, these cDNAs encode ATP-gated non-selective cation channels organized as trimers. All activated receptors produce cell depolarization and promote Ca(2+) influx through their pores and indirectly by activating voltage-gated calcium channels. However, the biophysical and pharmacological properties of these receptors differ considerably, and the majority of these subunits are also capable of forming heterotrimers with other members of the P2X receptor family, which confers further different properties. These channels have three ATP binding domains, presumably located between neighboring subunits, and occupancy of at least two binding sites is needed for their activation. In addition to the orthosteric binding sites for ATP, these receptors have additional allosteric sites that modulate the agonist action at receptors, including sites for trace metals, protons, neurosteroids, reactive oxygen species and phosphoinositides. The allosteric regulation of P2X receptors is frequently receptor-specific and could be a useful tool to identify P2X members in native tissues and their roles in signaling. The focus of this review is on common and receptor-specific allosteric modulation of P2X receptors and the molecular base accounting for allosteric binding sites.
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Affiliation(s)
- Claudio Coddou
- Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA.
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Jhamandas JH, Li Z, Westaway D, Yang J, Jassar S, MacTavish D. Actions of β-amyloid protein on human neurons are expressed through the amylin receptor. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 178:140-9. [PMID: 21224052 DOI: 10.1016/j.ajpath.2010.11.022] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/20/2010] [Accepted: 09/23/2010] [Indexed: 12/20/2022]
Abstract
Disruption of neurotoxic effects of amyloid β protein (Aβ) is one of the major, but as yet elusive, goals in the treatment of Alzheimer's disease (AD). The amylin receptor, activated by a pancreatic polypeptide isolated from diabetic patients, is a putative target for the actions of Aβ in the brain. Here we show that in primary cultures of human fetal neurons (HFNs), AC253, an amylin receptor antagonist, blocks electrophysiological effects of Aβ. Pharmacological blockade of the amylin receptor or its down-regulation using siRNA in HFNs confers neuroprotection against oligomeric Aβ-induced caspase-dependent and caspase-independent apoptotic cell death. In transgenic mice (TgCRND8) that overexpress amyloid precursor protein, amylin receptor is up-regulated in specific brain regions that also demonstrate an elevated amyloid burden. The expression of Aβ actions through the amylin receptor in human neurons and temporospatial interrelationship of Aβ and the amylin receptor in an in vivo model of AD together provide a persuasive rationale for this receptor as a novel therapeutic target in the treatment of AD.
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Affiliation(s)
- Jack H Jhamandas
- Division of Neurology, University of Alberta, Edmonton, Alberta, Canada.
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Abstract
Insulin replacement therapy in type 1 diabetes mellitus (T1DM) is nonphysiologic. Hyperinsulinemia is generated in the periphery to achieve normal insulin concentrations in the liver. This mismatch results in increased hypoglycemia, increased food intake with weight gain, and insufficient regulation of postprandial glucose excursions. Islet amyloid polypeptide is a hormone synthesized in pancreatic beta cells and cosecreted with insulin. Circulating islet amyloid polypeptide binds to receptors located in the hindbrain and increases satiety, delays gastric emptying and suppresses glucagon secretion. Thus, islet amyloid polypeptide complements the effects of insulin. T1DM is a state of both islet amyloid polypeptide and insulin deficiency. Pramlintide, a synthetic analog of islet amyloid polypeptide, can replace this hormone in patients with T1DM. When administered as adjunctive therapy to such patients treated with insulin, pramlintide decreases food intake and causes weight loss. Pramlintide therapy is also associated with suppression of glucagon secretion and delayed gastric emptying, both of which decrease postprandial plasma glucose excursions. Pramlintide therapy improves glycemic control and lessens weight gain. Agents that decrease intestinal carbohydrate digestion (alpha-glucosidase inhibitors) or decrease insulin resistance (metformin) might be alternative adjunctive therapies in T1DM, though its benefits are marginally supported by clinical data.
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Affiliation(s)
- Harold E Lebovitz
- Department of Medicine, Division of Endocrinology, State University of New York Health Science Center at Brooklyn, 450 Clarkson Avenue, New York, NY 11203, USA.
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Kenakin T, Miller LJ. Seven transmembrane receptors as shapeshifting proteins: the impact of allosteric modulation and functional selectivity on new drug discovery. Pharmacol Rev 2010; 62:265-304. [PMID: 20392808 DOI: 10.1124/pr.108.000992] [Citation(s) in RCA: 458] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
It is useful to consider seven transmembrane receptors (7TMRs) as disordered proteins able to allosterically respond to a number of binding partners. Considering 7TMRs as allosteric systems, affinity and efficacy can be thought of in terms of energy flow between a modulator, conduit (the receptor protein), and a number of guests. These guests can be other molecules, receptors, membrane-bound proteins, or signaling proteins in the cytosol. These vectorial flows of energy can yield standard canonical guest allostery (allosteric modification of drug effect), effects along the plane of the cell membrane (receptor oligomerization), or effects directed into the cytosol (differential signaling as functional selectivity). This review discusses these apparently diverse pharmacological effects in terms of molecular dynamics and protein ensemble theory, which tends to unify 7TMR behavior toward cells. Special consideration will be given to functional selectivity (biased agonism and biased antagonism) in terms of mechanism of action and potential therapeutic application. The explosion of technology that has enabled observation of diverse 7TMR behavior has also shown how drugs can have multiple (pluridimensional) efficacies and how this can cause paradoxical drug classification and nomenclatures.
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Affiliation(s)
- Terry Kenakin
- GlaxoSmithKline, 5 Moore Drive, Mailtstop V-287, Research Triangle Park, NC 27709, USA.
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Vaiana SM, Best RB, Yau WM, Eaton WA, Hofrichter J. Evidence for a partially structured state of the amylin monomer. Biophys J 2010; 97:2948-57. [PMID: 19948124 DOI: 10.1016/j.bpj.2009.08.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2009] [Revised: 07/29/2009] [Accepted: 08/03/2009] [Indexed: 10/20/2022] Open
Abstract
Islet amyloid polypeptide (amylin) is the main component in amyloid deposits formed in type II diabetes. We used triplet quenching to probe the dynamics of contact formation between the N-terminal disulfide loop and a C-terminal tryptophan in monomeric amylins from human and rat. Quenching rates measured in the absence of denaturant are four times larger than those in 6 M guanidinium chloride, indicating a decrease in the average end-to-end distance (collapse) at low denaturant concentrations. We were surprised to find an even greater (sevenfold) increase in quenching rates on removal of denaturant for a hydrophilic control peptide containing the disulfide loop compared to the same peptide without the loop (twofold change). These results suggest that collapse is driven by backbone-backbone and backbone-side chain interactions involving the disulfide loop portion of the chain rather than by the formation of side-chain hydrophobic contacts. Molecular dynamics simulations of the control peptide show that the collapse results from hydrogen-bonding interactions between the central residues of the chain and the disulfide loop. The quenching experiments also indicate that the monomer of the human, amyloidogenic form of amylin is more compact than the rat form, which does not form amyloid. We discuss these newly observed differences between human and rat amylin in solution and their possible relation to aggregation and to the physiological function of amylin binding to the calcitonin receptor.
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Affiliation(s)
- Sara M Vaiana
- Laboratory of Chemical Physics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
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Hebda JA, Saraogi I, Magzoub M, Hamilton AD, Miranker AD. A peptidomimetic approach to targeting pre-amyloidogenic states in type II diabetes. ACTA ACUST UNITED AC 2010; 16:943-50. [PMID: 19778722 DOI: 10.1016/j.chembiol.2009.08.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 08/20/2009] [Accepted: 08/27/2009] [Indexed: 12/21/2022]
Abstract
Protein fiber formation is associated with diseases ranging from Alzheimer's to type II diabetes. For many systems, including islet amyloid polypeptide (IAPP) from type II diabetes, fibrillogenesis can be catalyzed by lipid bilayers. Paradoxically, amyloid fibers are beta sheet rich while membrane-stabilized states are alpha-helical. Here, a small molecule alpha helix mimetic, IS5, is shown to inhibit bilayer catalysis of fibrillogenesis and to rescue IAPP-induced toxicity in cell culture. Importantly, IAPP:IS5 interactions localize to the putative alpha-helical region of IAPP, revealing that alpha-helical states are on pathway to fiber formation. IAPP is not normally amyloidogenic as its cosecreted partner, insulin, prevents self-assembly. Here, we show that IS5 inhibition is synergistic with insulin. IS5 therefore represents a new approach to amyloid inhibition as the target is an assembly intermediate that may additionally restore functional IAPP expression.
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Affiliation(s)
- James A Hebda
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, CT 06520-8114, USA
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Mack CM, Soares CJ, Wilson JK, Athanacio JR, Turek VF, Trevaskis JL, Roth JD, Smith PA, Gedulin B, Jodka CM, Roland BL, Adams SH, Lwin A, Herich J, Laugero KD, Vu C, Pittner R, Paterniti JR, Hanley M, Ghosh S, Parkes DG. Davalintide (AC2307), a novel amylin-mimetic peptide: enhanced pharmacological properties over native amylin to reduce food intake and body weight. Int J Obes (Lond) 2009; 34:385-95. [PMID: 19935749 DOI: 10.1038/ijo.2009.238] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The current set of studies describe the in vivo metabolic actions of the novel amylin-mimetic peptide davalintide (AC2307) in rodents and compares these effects with those of the native peptide. RESEARCH DESIGN AND METHODS The anti-obesity effects of davalintide were examined after intraperitoneal injection or sustained peripheral infusion through subcutaneously implanted osmotic pumps. The effect of davalintide on food intake after lesioning of the area postrema (AP) and neuronal activation as measured by c-Fos, were also investigated. RESULTS Similar to amylin, davalintide bound with high affinity to amylin, calcitonin and calcitonin gene-related peptide receptors. Acutely, davalintide displayed greater suppression of dark-cycle feeding and an extended duration of action compared with amylin (23 versus 6 h). Davalintide had no effect on locomotor activity or kaolin consumption at doses that decreased food intake. Davalintide-induced weight loss through infusion was dose dependent, durable up to 8 weeks, fat-specific and lean-sparing, and was associated with a shift in food preference away from high-fat (palatable) chow. Metabolic rate was maintained during active weight loss. Both davalintide and amylin failed to suppress food intake after lesioning of the AP and activated similar brain nuclei, with davalintide displaying an extended duration of c-Fos expression compared with amylin (8 versus 2 h). CONCLUSION Davalintide displayed enhanced in vivo metabolic activity over amylin while retaining the beneficial properties possessed by the native molecule. In vitro receptor binding, c-Fos expression and AP lesion studies suggest that the metabolic actions of davalintide and amylin occur through activation of similar neuronal pathways.
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Affiliation(s)
- C M Mack
- Amylin Pharmaceuticals, San Diego, CA, USA
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Kenakin TP. Cellular assays as portals to seven-transmembrane receptor-based drug discovery. Nat Rev Drug Discov 2009; 8:617-26. [PMID: 19609267 DOI: 10.1038/nrd2838] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
As technology advances to the point at which various behaviours of seven-transmembrane (7TM) receptors (also known as G protein-coupled receptors (GPCRs)) can be observed individually, it is clear that, rather than being 'on-off' switches, 7TM receptors are more akin to 'microprocessors' of information. This has introduced the phenomenon of functional selectivity, whereby certain ligands initiate only portions of the signalling mechanisms mediated by a given receptor, which has opened new horizons for drug discovery. The need to discover new 7TM receptor-ligand behaviours and quantify the effect of the drug on these complex systems, to guide medicinal chemistry, puts the pharmacological assay into the spotlight. This Perspective outlines the return to whole-system assays from reductionist recombinant systems, and discusses how the efficacy of a drug is linked to the particular assay used to observe its effects. It also highlights how these new assays are adding value to the drug discovery process.
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Affiliation(s)
- Terry P Kenakin
- Department of Biological Reagents and Assay Development, GlaxoSmithKline Research and Development, 5 Moore Drive, Research Triangle Park, NC 27709, USA.
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50
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Kenakin T. Interrogating 7TM receptors: Does texture in the question yield greater texture in the answer? J Recept Signal Transduct Res 2009; 29:132-9. [DOI: 10.1080/10799890903050829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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