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Hay DL, Chen S, Lutz TA, Parkes DG, Roth JD. Amylin: Pharmacology, Physiology, and Clinical Potential. Pharmacol Rev 2016; 67:564-600. [PMID: 26071095 DOI: 10.1124/pr.115.010629] [Citation(s) in RCA: 231] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Amylin is a pancreatic β-cell hormone that produces effects in several different organ systems. Here, we review the literature in rodents and in humans on amylin research since its discovery as a hormone about 25 years ago. Amylin is a 37-amino-acid peptide that activates its specific receptors, which are multisubunit G protein-coupled receptors resulting from the coexpression of a core receptor protein with receptor activity-modifying proteins, resulting in multiple receptor subtypes. Amylin's major role is as a glucoregulatory hormone, and it is an important regulator of energy metabolism in health and disease. Other amylin actions have also been reported, such as on the cardiovascular system or on bone. Amylin acts principally in the circumventricular organs of the central nervous system and functionally interacts with other metabolically active hormones such as cholecystokinin, leptin, and estradiol. The amylin-based peptide, pramlintide, is used clinically to treat type 1 and type 2 diabetes. Clinical studies in obesity have shown that amylin agonists could also be useful for weight loss, especially in combination with other agents.
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Affiliation(s)
- Debbie L Hay
- School of Biological Sciences, Maurice Wilkins Centre for Molecular Biodiscovery and Centre for Brain Research, University of Auckland, Auckland, New Zealand (D.L.H.); Amylin Pharmaceuticals LLC, San Diego, California (S.C., D.G.P.); Institute of Veterinary Physiology, Institute of Laboratory Animal Sciences and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland (T.A.L.); and Intercept Pharmaceuticals, Inc., San Diego, California (J.D.R.)
| | - Steve Chen
- School of Biological Sciences, Maurice Wilkins Centre for Molecular Biodiscovery and Centre for Brain Research, University of Auckland, Auckland, New Zealand (D.L.H.); Amylin Pharmaceuticals LLC, San Diego, California (S.C., D.G.P.); Institute of Veterinary Physiology, Institute of Laboratory Animal Sciences and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland (T.A.L.); and Intercept Pharmaceuticals, Inc., San Diego, California (J.D.R.)
| | - Thomas A Lutz
- School of Biological Sciences, Maurice Wilkins Centre for Molecular Biodiscovery and Centre for Brain Research, University of Auckland, Auckland, New Zealand (D.L.H.); Amylin Pharmaceuticals LLC, San Diego, California (S.C., D.G.P.); Institute of Veterinary Physiology, Institute of Laboratory Animal Sciences and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland (T.A.L.); and Intercept Pharmaceuticals, Inc., San Diego, California (J.D.R.)
| | - David G Parkes
- School of Biological Sciences, Maurice Wilkins Centre for Molecular Biodiscovery and Centre for Brain Research, University of Auckland, Auckland, New Zealand (D.L.H.); Amylin Pharmaceuticals LLC, San Diego, California (S.C., D.G.P.); Institute of Veterinary Physiology, Institute of Laboratory Animal Sciences and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland (T.A.L.); and Intercept Pharmaceuticals, Inc., San Diego, California (J.D.R.)
| | - Jonathan D Roth
- School of Biological Sciences, Maurice Wilkins Centre for Molecular Biodiscovery and Centre for Brain Research, University of Auckland, Auckland, New Zealand (D.L.H.); Amylin Pharmaceuticals LLC, San Diego, California (S.C., D.G.P.); Institute of Veterinary Physiology, Institute of Laboratory Animal Sciences and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland (T.A.L.); and Intercept Pharmaceuticals, Inc., San Diego, California (J.D.R.)
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Smith PM, Brzezinska P, Hubert F, Mimee A, Maurice DH, Ferguson AV. Leptin influences the excitability of area postrema neurons. Am J Physiol Regul Integr Comp Physiol 2015; 310:R440-8. [PMID: 26719304 DOI: 10.1152/ajpregu.00326.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 12/23/2015] [Indexed: 11/22/2022]
Abstract
The area postrema (AP) is a circumventricular organ with important roles in central autonomic regulation. This medullary structure has been shown to express the leptin receptor and has been suggested to have a role in modulating peripheral signals, indicating energy status. Using RT-PCR, we have confirmed the presence of mRNA for the leptin receptor, ObRb, in AP, and whole cell current-clamp recordings from dissociated AP neurons demonstrated that leptin influenced the excitability of 51% (42/82) of AP neurons. The majority of responsive neurons (62%) exhibited a depolarization (5.3 ± 0.7 mV), while the remaining affected cells (16/42) demonstrated hyperpolarizing effects (-5.96 ± 0.95 mV). Amylin was found to influence the same population of AP neurons. To elucidate the mechanism(s) of leptin and amylin actions in the AP, we used fluorescence resonance energy transfer (FRET) to determine the effect of these peptides on cAMP levels in single AP neurons. Leptin and amylin were found to elevate cAMP levels in the same dissociated AP neurons (leptin: % total FRET response 25.3 ± 4.9, n = 14; amylin: % total FRET response 21.7 ± 3.1, n = 13). When leptin and amylin were coapplied, % total FRET response rose to 53.0 ± 8.3 (n = 6). The demonstration that leptin and amylin influence a subpopulation of AP neurons and that these two signaling molecules have additive effects on single AP neurons to increase cAMP, supports a role for the AP as a central nervous system location at which these circulating signals may act through common intracellular signaling pathways to influence central control of energy balance.
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Affiliation(s)
- Pauline M Smith
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Paulina Brzezinska
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Fabien Hubert
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Andrea Mimee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Donald H Maurice
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Alastair V Ferguson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Akter R, Cao P, Noor H, Ridgway Z, Tu LH, Wang H, Wong AG, Zhang X, Abedini A, Schmidt AM, Raleigh DP. Islet Amyloid Polypeptide: Structure, Function, and Pathophysiology. J Diabetes Res 2015; 2016:2798269. [PMID: 26649319 PMCID: PMC4662979 DOI: 10.1155/2016/2798269] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/24/2015] [Indexed: 01/29/2023] Open
Abstract
The hormone islet amyloid polypeptide (IAPP, or amylin) plays a role in glucose homeostasis but aggregates to form islet amyloid in type-2 diabetes. Islet amyloid formation contributes to β-cell dysfunction and death in the disease and to the failure of islet transplants. Recent work suggests a role for IAPP aggregation in cardiovascular complications of type-2 diabetes and hints at a possible role in type-1 diabetes. The mechanisms of IAPP amyloid formation in vivo or in vitro are not understood and the mechanisms of IAPP induced β-cell death are not fully defined. Activation of the inflammasome, defects in autophagy, ER stress, generation of reactive oxygen species, membrane disruption, and receptor mediated mechanisms have all been proposed to play a role. Open questions in the field include the relative importance of the various mechanisms of β-cell death, the relevance of reductionist biophysical studies to the situation in vivo, the molecular mechanism of amyloid formation in vitro and in vivo, the factors which trigger amyloid formation in type-2 diabetes, the potential role of IAPP in type-1 diabetes, the development of clinically relevant inhibitors of islet amyloidosis toxicity, and the design of soluble, bioactive variants of IAPP for use as adjuncts to insulin therapy.
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Affiliation(s)
- Rehana Akter
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Harris Noor
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Zachary Ridgway
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Hui Wang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Amy G. Wong
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Xiaoxue Zhang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Andisheh Abedini
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Ann Marie Schmidt
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
- Research Department of Structural and Molecule Biology, University College London, Gower Street, London WC1E 6BT, UK
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Lutz TA, Meyer U. Amylin at the interface between metabolic and neurodegenerative disorders. Front Neurosci 2015; 9:216. [PMID: 26136651 PMCID: PMC4468610 DOI: 10.3389/fnins.2015.00216] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 05/29/2015] [Indexed: 12/14/2022] Open
Abstract
The pancreatic peptide amylin is best known for its role as a satiation hormone in the control of food intake and as the major component of islet amyloid deposits in the pancreatic islets of patients with type 2 diabetes mellitus (T2DM). Epidemiological studies have established a clear association between metabolic and neurodegenerative disorders in general, and between T2DM and Alzheimer's disease (AD) in particular. Here, we discuss that amylin may be an important player acting at the interface between these metabolic and neurodegenerative disorders. Abnormal amylin production is a hallmark peripheral pathology both in the early (pre-diabetic) and late phases of T2DM, where hyperamylinemic (early phase) and hypoamylinemic (late phase) conditions coincide with hyper- and hypo-insulinemia, respectively. Moreover, there are notable biochemical similarities between amylin and β-amyloids (Aβ), which are both prone to amyloid plaque formation and to cytotoxic effects. Amylin's propensity to form amyloid plaques is not restricted to pancreatic islet cells, but readily extends to the CNS, where it has been found to co-localize with Aβ plaques in at least a subset of AD patients. Hence, amylin may constitute a “second amyloid” in neurodegenerative disorders such as AD. We further argue that hyperamylinemic conditions may be more relevant for the early processes of amyloid formation in the CNS, whereas hypoamylinemic conditions may be more strongly associated with late stages of central amyloid pathologies. Advancing our understanding of these temporal relationships may help to establish amylin-based interventions in the treatment of AD and other neurodegenerative disorders with metabolic comorbidities.
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Affiliation(s)
- Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich Zurich, Switzerland ; Zurich Center of Integrative Human Physiology, University of Zurich Zurich, Switzerland
| | - Urs Meyer
- Institute of Veterinary Pharmacology and Toxicology, University of Zurich Zurich, Switzerland
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Abstract
Migraine is a highly prevalent headache disease that typically affects patients during their most productive years. Despite significant progress in understanding the underlying pathophysiology of this disorder, its treatment so far continues to depend on drugs that, in their majority, were not specifically designed for this purpose. The neuropeptide calcitonin gene-related peptide (CGRP) has been indicated as playing a critical role in the central and peripheral pathways leading to a migraine attack. It is not surprising that drugs designed to specifically block its action are gaining remarkable attention from researchers in the field with, at least so far, a safe risk profile. In this article, we highlight the evolution from older traditional treatments to the innovative CGRP target drugs that are revolutionizing the way to approach this debilitating neurological disease. We provide a brief introduction on pathophysiology of migraine and details on the characteristic, function, and localization of CGRP to then focus on CGRP receptor antagonists (CGRP-RAs) and CGRP monoclonal antibodies (CGRP mAbs).
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Affiliation(s)
- Stephanie Wrobel Goldberg
- Department of Neurology, Jefferson Headache Center, Thomas Jefferson University, 900 Walnut Street, Suite 200, Philadelphia, PA, 19107, USA,
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56
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Walker CS, Eftekhari S, Bower RL, Wilderman A, Insel PA, Edvinsson L, Waldvogel HJ, Jamaluddin MA, Russo AF, Hay DL. A second trigeminal CGRP receptor: function and expression of the AMY1 receptor. Ann Clin Transl Neurol 2015; 2:595-608. [PMID: 26125036 PMCID: PMC4479521 DOI: 10.1002/acn3.197] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 03/01/2015] [Accepted: 03/02/2015] [Indexed: 12/14/2022] Open
Abstract
Objective The trigeminovascular system plays a central role in migraine, a condition in need of new treatments. The neuropeptide, calcitonin gene-related peptide (CGRP), is proposed as causative in migraine and is the subject of intensive drug discovery efforts. This study explores the expression and functionality of two CGRP receptor candidates in the sensory trigeminal system. Methods Receptor expression was determined using Taqman G protein-coupled receptor arrays and immunohistochemistry in trigeminal ganglia (TG) and the spinal trigeminal complex of the brainstem in rat and human. Receptor pharmacology was quantified using sensitive signaling assays in primary rat TG neurons. Results mRNA and histological expression analysis in rat and human samples revealed the presence of two CGRP-responsive receptors (AMY1: calcitonin receptor/receptor activity-modifying protein 1 [RAMP1]) and the CGRP receptor (calcitonin receptor-like receptor/RAMP1). In support of this finding, quantification of agonist and antagonist potencies revealed a dual population of functional CGRP-responsive receptors in primary rat TG neurons. Interpretation The unexpected presence of a functional non-canonical CGRP receptor (AMY1) at neural sites important for craniofacial pain has important implications for targeting the CGRP axis in migraine.
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Affiliation(s)
- Christopher S Walker
- School of Biological Sciences, University of Auckland Auckland, 1142, New Zealand ; Centre for Brain Research, University of Auckland Auckland, 1142, New Zealand
| | - Sajedeh Eftekhari
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University Lund, Sweden
| | - Rebekah L Bower
- School of Biological Sciences, University of Auckland Auckland, 1142, New Zealand ; Centre for Brain Research, University of Auckland Auckland, 1142, New Zealand
| | - Andrea Wilderman
- Departments of Pharmacology and Medicine, University of California at San Diego La Jolla, California
| | - Paul A Insel
- Departments of Pharmacology and Medicine, University of California at San Diego La Jolla, California
| | - Lars Edvinsson
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University Lund, Sweden
| | - Henry J Waldvogel
- Centre for Brain Research, University of Auckland Auckland, 1142, New Zealand ; Department of Anatomy with Radiology, Faculty of Medical and Health Science, University of Auckland Auckland, 1142, New Zealand
| | | | - Andrew F Russo
- Department of Molecular Physiology and Biophysics, University of Iowa Iowa City, Iowa ; Department of Neurology, Veterans Affairs Medical Center, University of Iowa Iowa City, Iowa
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland Auckland, 1142, New Zealand ; Centre for Brain Research, University of Auckland Auckland, 1142, New Zealand
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Terra SR, Cardoso JCR, Félix RC, Martins LAM, Souza DOG, Guma FCR, Canário AVM, Schein V. STC1 interference on calcitonin family of receptors signaling during osteoblastogenesis via adenylate cyclase inhibition. Mol Cell Endocrinol 2015; 403:78-87. [PMID: 25591908 DOI: 10.1016/j.mce.2015.01.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/15/2014] [Accepted: 01/06/2015] [Indexed: 12/24/2022]
Abstract
Stanniocalcin 1 (STC1) and calcitonin gene-related peptide (CGRP) are involved in bone formation/remodeling. Here we investigate the effects of STC1 on functional heterodimer complex CALCRL/RAMP1, expression and activity during osteoblastogenesis. STC1 did not modify CALCRL and ramp1 gene expression during osteoblastogenesis when compared to controls. However, plasma membrane spatial distribution of CALCRL/RAMP1 was modified in 7-day pre-osteoblasts exposed to either CGRP or STC1, and both peptides induced CALCRL and RAMP1 assembly. CGRP, but not STC1 stimulated cAMP accumulation in 7-day osteoblasts and in CALCRL/RAMP1 transfected HEK293 cells. Furthermore, STC1 inhibited forskolin stimulated cAMP accumulation of HEK293 cells, but not in CALCRL/RAMP1 transfected HEK293 cells. However, STC1 inhibited cAMP accumulation in calcitonin receptor (CTR) HEK293 transfected cells stimulated by calcitonin. In conclusion, STC1 signals through inhibitory G-protein modulates CGRP receptor spatial localization during osteoblastogenesis and may function as a regulatory factor interacting with calcitonin peptide members during bone formation.
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Affiliation(s)
- Silvia R Terra
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - João Carlos R Cardoso
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal
| | - Rute C Félix
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal
| | - Leo Anderson M Martins
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - Diogo Onofre G Souza
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - Fatima C R Guma
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - Adelino Vicente M Canário
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal
| | - Vanessa Schein
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil; Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal.
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Khoshdel Z, Takhshid MA, Owji AA. Intrathecal Amylin and Salmon Calcitonin Affect Formalin Induced c-Fos Expression in the Spinal Cord of Rats. IRANIAN JOURNAL OF MEDICAL SCIENCES 2014; 39:543-51. [PMID: 25429177 PMCID: PMC4242989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 03/04/2014] [Accepted: 03/09/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Amylin and Salmon Calcitonin belong to the calcitonin family of peptides and have high affinity binding sites in the rat spinal cord. The aim of this study was to characterize receptors for Amylin and Salmon Calcitonin functionally in the spinal cord of rats. We assessed the expression of c-Fos in response to intraplantar formalin in the lumbar regions of the spinal cord in conscious rats. METHODS Amylin (0.05 nmoles) or Salmon Calcitonin (0.005 nmoles) was administered intrathecally (i.t.) 10 minutes before the start of the formalin test. Antagonists were injected intrathecally 10 minutes before the administration of either of the peptides. RESULTS Two hours after formalin stimulation, rats pretreated intrathecally by either Amylin or Salmon Calcitonin, showed lower numbers of c-Fos immunoreactive nuclei in their lumbar spinal cord as compared to rats pretreated with saline. These effects were reversed upon co-administration of either of the Amylin antagonists AC187 or rat amylin8-37, but not rat α-CGRP8-37 (.) A few cells with c-Fos immunoreactivity were found in the lumbar spinal cord of rats two hours after i.t. injection of saline, Amylin and/or Salmon Calcitonin. However, Fos-like immunoreactivity was increased in the lumbar spinal cord two hours after i.t. treatment of either of the antagonists AC187 and rat amylin8-37,when compared to saline treated rats. CONCLUSION Both Amylin and Salmon Calcitonin inhibit formalin induced c-Fos expression in the rat lumbar spinal cord when administered intrathecally. Effects of the two peptides were possibly produced by undefined receptors.
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Affiliation(s)
- Zahra Khoshdel
- Department of Biochemistry Recombinant Protein Laboratory, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran;
| | - Mohammad Ali Takhshid
- Diagnostic Laboratory Sciences and Technology Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran;
| | - Ali Akbar Owji
- Research Center for Psychiatry and Behavioral Sciences, Department of Psychiatry, Hafez Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
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Hay DL, Harris PWR, Kowalczyk R, Brimble MA, Rathbone DL, Barwell J, Conner AC, Poyner DR. Structure-activity relationships of the N-terminus of calcitonin gene-related peptide: key roles of alanine-5 and threonine-6 in receptor activation. Br J Pharmacol 2014; 171:415-26. [PMID: 24125506 PMCID: PMC3904261 DOI: 10.1111/bph.12464] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/10/2013] [Accepted: 10/07/2013] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND AND PURPOSE The N-terminus of calcitonin gene-related peptide (CGRP) is important for receptor activation, especially the disulphide-bonded ring (residues 1-7). However, the roles of individual amino acids within this region have not been examined and so the molecular determinants of agonism are unknown. This study has examined the role of residues 1, 3-6 and 8-9, excluding Cys-2 and Cys-7. EXPERIMENTAL APPROACH CGRP derivatives were substituted with either cysteine or alanine; further residues were introduced at position 6. Their affinity was measured by radioligand binding and their efficacy by measuring cAMP production in SK-N-MC cells and β-arrestin 2 translocation in CHO-K1 cells at the CGRP receptor. KEY RESULTS Substitution of Ala-5 by cysteine reduced affinity 270-fold and reduced efficacy for production of cAMP in SK-N-MCs. Potency at β-arrestin translocation was reduced by ninefold. Substitution of Thr-6 by cysteine destroyed all measurable efficacy of both cAMP and β-arrestin responses; substitution with either alanine or serine impaired potency. Substitutions at positions 1, 4, 8 and 9 resulted in approximately 10-fold reductions in potency at both responses. Similar observations were made at a second CGRP-activated receptor, the AMY(1(a)) receptor. CONCLUSIONS AND IMPLICATIONS Ala-5 and Thr-6 are key determinants of agonist activity for CGRP. Ala-5 is also very important for receptor binding. Residues outside of the 1-7 ring also contribute to agonist activity.
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Affiliation(s)
- Debbie L Hay
- School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
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Buhmann H, le Roux CW, Bueter M. The gut-brain axis in obesity. Best Pract Res Clin Gastroenterol 2014; 28:559-71. [PMID: 25194175 DOI: 10.1016/j.bpg.2014.07.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 06/11/2014] [Accepted: 07/05/2014] [Indexed: 01/31/2023]
Abstract
Currently the only effective treatment for morbid obesity with a proven mortality benefit is surgical intervention. The underlying mechanisms of these surgical techniques are unclear, but alterations in circulating gut hormone levels have been demonstrated to be at least one contributing factor. Gut hormones seem to communicate information from the gastrointestinal tract to the regulatory appetite centres within the central nervous system (CNS) via the so-called 'Gut-Brain-Axis'. Such information may be transferred to the CNS either via vagal or non-vagal afferent nerve signalling or directly via blood circulation. Complex neural networks, distributed throughout the forebrain and brainstem, are in control of feeding and energy homoeostasis. This article aims to review how appetite is potentially regulated by these gastrointestinal hormones. Identification of the underlying mechanisms of appetite and weight control may pave the way to develop better surgical techniques and new therapies in the future.
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Affiliation(s)
- Helena Buhmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Switzerland
| | - Carel W le Roux
- Diabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin, Ireland; Gastrosurgical Laboratory, University of Gothenburg, Sweden
| | - Marco Bueter
- Department of Surgery, Division of Visceral and Transplantation Surgery, University Hospital Zurich, Zurich, Switzerland; Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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Walker CS, Hay DL, Fitzpatrick SM, Cooper GJS, Loomes KM. α-Calcitonin gene related peptide (α-CGRP) mediated lipid mobilization in 3T3-L1 adipocytes. Peptides 2014; 58:14-9. [PMID: 24887115 DOI: 10.1016/j.peptides.2014.05.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/21/2014] [Accepted: 05/21/2014] [Indexed: 11/29/2022]
Abstract
The neuropeptide, α-calcitonin gene-related peptide (α-CGRP), is expressed from sensory nerves that innervate fat. However, how α-CGRP may act in adipose tissue is unclear. Using 3T3-L1 adipocytes we observed that rat α-CGRP (rα-CGRP) evoked either a biphasic or monophasic reduction in intracellular free fatty acid (FFA) content. cAMP production was always monophasic and occurred when FFA responses were absent. Taken together with the observed potencies, these findings suggest that adipose tissue is a physiological target for α-CGRP. However, uncoupling of the FFA and CGRP-signaling responses with increasing passage number limits 3T3-L1 adipocytes as a suitable cellular model.
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Affiliation(s)
- Christopher S Walker
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand.
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
| | | | - Garth J S Cooper
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
| | - Kerry M Loomes
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand.
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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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Gingell JJ, Burns ER, Hay DL. Activity of pramlintide, rat and human amylin but not Aβ1-42 at human amylin receptors. Endocrinology 2014; 155:21-6. [PMID: 24169554 DOI: 10.1210/en.2013-1658] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Amylin is a neuroendocrine hormone involved in glucose regulation. An amylin analog, pramlintide, is used to treat insulin-requiring diabetes. Its anorexigenic actions give it potential as an obesity treatment. There are 3 amylin receptors (AMY1, AMY2, AMY3), comprising the calcitonin receptor and receptor activity-modifying proteins 1, 2, and 3, respectively. The pharmacology of pramlintide at each subtype has not been determined whereas the unrelated peptide β-amyloid 1-42 (Aβ1-42) has recently been proposed to be a specific agonist of the AMY3 receptor. We investigated the actions of Aβ1-42 and pramlintide, compared with human and rat amylin at the calcitonin receptor, AMY1, AMY2, and AMY3 receptors, measuring the cAMP response in human embryonic kidney 293S and Cos 7 cells. Pramlintide activated all receptors with a slight preference for AMY1. No cAMP response was detected with Aβ1-42 at any receptor, suggesting that it may not be a genuine agonist of AMY receptors.
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Affiliation(s)
- Joseph J Gingell
- School of Biological Sciences (J.J.G., E.R.B., D.L.H.), The University of Auckland and Maurice Wilkins Centre (J.J.G., D.L.H.), University of Auckland, Auckland 1142, New Zealand
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64
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Trikha S, Jeremic AM. Distinct internalization pathways of human amylin monomers and its cytotoxic oligomers in pancreatic cells. PLoS One 2013; 8:e73080. [PMID: 24019897 PMCID: PMC3760900 DOI: 10.1371/journal.pone.0073080] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/15/2013] [Indexed: 01/06/2023] Open
Abstract
Toxic human amylin oligomers and aggregates are implicated in the pathogenesis of type 2 diabetes mellitus (TTDM). Although recent studies have shown that pancreatic cells can recycle amylin monomers and toxic oligomers, the exact uptake mechanism and trafficking routes of these molecular forms and their significance for amylin toxicity are yet to be determined. Using pancreatic rat insulinoma (RIN-m5F) beta (β)-cells and human islets as model systems we show that monomers and oligomers cross the plasma membrane (PM) through both endocytotic and non-endocytotic (translocation) mechanisms, the predominance of which is dependent on amylin concentrations and incubation times. At low (≤ 100 nM) concentrations, internalization of amylin monomers in pancreatic cells is completely blocked by the selective amylin-receptor (AM-R) antagonist, AC-187, indicating an AM-R dependent mechanism. In contrast at cytotoxic (µM) concentrations monomers initially (1 hour) enter pancreatic cells by two distinct mechanisms: translocation and macropinocytosis. However, during the late stage (24 hours) monomers internalize by a clathrin-dependent but AM-R and macropinocytotic independent pathway. Like monomers a small fraction of the oligomers initially enter cells by a non-endocytotic mechanism. In contrast a majority of the oligomers at both early (1 hour) and late times (24 hours) traffic with a fluid-phase marker, dextran, to the same endocytotic compartments, the uptake of which is blocked by potent macropinocytotic inhibitors. This led to a significant increase in extra-cellular PM accumulation, in turn potentiating amylin toxicity in pancreatic cells. Our studies suggest that macropinocytosis is a major but not the only clearance mechanism for both amylin's molecular forms, thereby serving a cyto-protective role in these cells.
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Affiliation(s)
- Saurabh Trikha
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia, United States of America
| | - Aleksandar M. Jeremic
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia, United States of America
- * E-mail:
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Yan LM, Velkova A, Tatarek-Nossol M, Rammes G, Sibaev A, Andreetto E, Kracklauer M, Bakou M, Malideli E, Göke B, Schirra J, Storr M, Kapurniotu A. Selektiv N-methylierte lösliche IAPP-Mimetika als potente IAPP-Rezeptoragonisten und nanomolare Inhibitoren der Selbstassoziation von IAPP und Aβ40. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302840] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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66
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Yan LM, Velkova A, Tatarek-Nossol M, Rammes G, Sibaev A, Andreetto E, Kracklauer M, Bakou M, Malideli E, Göke B, Schirra J, Storr M, Kapurniotu A. Selectively N-methylated soluble IAPP mimics as potent IAPP receptor agonists and nanomolar inhibitors of cytotoxic self-assembly of both IAPP and Aβ40. Angew Chem Int Ed Engl 2013; 52:10378-83. [PMID: 23956012 DOI: 10.1002/anie.201302840] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 06/08/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Li-Mei Yan
- Division of Peptide Biochemistry, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising (Germany) http://pbch.wzw.tum.de/
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67
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Züger D, Forster K, Lutz TA, Riediger T. Amylin and GLP-1 target different populations of area postrema neurons that are both modulated by nutrient stimuli. Physiol Behav 2013; 112-113:61-9. [PMID: 23438370 DOI: 10.1016/j.physbeh.2013.02.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 01/16/2013] [Accepted: 02/13/2013] [Indexed: 01/11/2023]
Abstract
The area postrema mediates the hypophagic effect of the pancreatic hormone amylin and is also sensitive to glucagon-like peptide 1 (GLP-1). Protein seems to modulate amylin responsiveness because amylin seems to produce a stronger hypophagic effect and a stronger c-Fos expression when protein is absent from the diet. Accordingly, amylin induces a stronger c-Fos expression in the AP when injected in fasted compared to ad libitum fed rats. Here we tested the hypothesis that diet-derived protein attenuates the amylin dependent suppression of feeding and AP activation using isocaloric diets that differed in their protein content. Moreover, we investigated whether peripheral amino acid injection attenuates amylin-induced c-Fos expression in fasted rats. Since recent evidence suggests that GLP-1 may also reduce eating via the AP we tested whether 24 h fasting also increases neuronal AP responsiveness to GLP-1 similar to the fasting-induced increase in amylin responsiveness. Finally, we used the calcitonin receptor (CTR) as an immunohistochemical marker for amylin-receptive AP neurons to investigate whether amylin's target neurons differ from GLP-1 responsive AP neurons. We also dissociated amylin responsive cells from neurons implicated in other AP-mediated functions such as aversion or blood pressure regulation. For this purpose, we conducted c-Fos/CTR double staining after LiCl or angiotensin II treatment, respectively. Amylin (5 μg/kg s.c.) was more effective to reduce the intake of a 1% vs. an 8% or 18% protein diet and to induce c-Fos expression in the AP in rats receiving 1% vs. 18% protein diet. Increased protein intake was associated with increased blood amino acid levels. Peripheral injection of amino acids (1 g/kg i.p.) attenuated the amylin-induced AP activation in 24 h fasted rats. Similar to amylin, GLP-1 (100 μg/kg i.p.) elicited a significant c-Fos response only in fasted but not in ad libitum fed rats. However, in contrast to a high co-localization of amylin-induced c-Fos and CTR (68%), no c-Fos/CTR co-localization occurred after treatment with GLP-1 or the GLP-1R agonist exendin 4 (2 μg/kg ip). Similarly, LiCl (76 mg/kg ip) or AngII (50 μg/kg sc) led to c-Fos expression only in CTR negative AP neurons. In conclusion, our findings support a protein-dependent modulation of behavioral and neuronal amylin responsiveness under equicaloric feeding conditions. Amino acids might contribute to the inhibitory effect of diet-derived protein to reduce amylin-induced neuronal AP activation. Neuronal AP responsiveness to GLP-1 is also increased in the fasted state suggesting that diet-derived nutrients may also interfere with AP-mediated GLP-1 effects. Nevertheless, the primary target neurons for amylin appear to be distinct from cells targeted by GLP-1 and by stimuli producing aversion (LiCl) or contributing to blood pressure regulation (AngII) via the AP. Since amylin and GLP-1 analogs are targets for the treatment of obesity, the nutrient-dependent modulation of AP responsiveness might entail implications for such therapeutic approaches.
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Affiliation(s)
- Daniela Züger
- Institute of Veterinary Physiology, University of Zurich, 8057 Zurich, Switzerland
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68
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Cao P, Marek P, Noor H, Patsalo V, Tu LH, Wang H, Abedini A, Raleigh DP. Islet amyloid: from fundamental biophysics to mechanisms of cytotoxicity. FEBS Lett 2013; 587:1106-18. [PMID: 23380070 DOI: 10.1016/j.febslet.2013.01.046] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/22/2013] [Accepted: 01/23/2013] [Indexed: 12/21/2022]
Abstract
Pancreatic islet amyloid is a characteristic feature of type 2 diabetes. The major protein component of islet amyloid is the polypeptide hormone known as islet amyloid polypeptide (IAPP, or amylin). IAPP is stored with insulin in the β-cell secretory granules and is released in response to the stimuli that lead to insulin secretion. IAPP is normally soluble and is natively unfolded in its monomeric state, but forms islet amyloid in type 2 diabetes. Islet amyloid is not the cause of type 2 diabetes, but it leads to β-cell dysfunction and cell death, and contributes to the failure of islet cell transplantation. The mechanism of IAPP amyloid formation is not understood and the mechanisms of cytotoxicity are not fully defined.
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Affiliation(s)
- Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
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69
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Poyner DR, Hay DL. Secretin family (Class B) G protein-coupled receptors - from molecular to clinical perspectives. Br J Pharmacol 2012; 166:1-3. [PMID: 22489621 DOI: 10.1111/j.1476-5381.2011.01810.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Family B G protein-coupled receptors represent an important but under-researched group of receptors. This edition of the British Journal of Pharmacology considers the roles and pharmacology of a number of these receptors. Whilst common themes emerge, it is clear that more work is needed to understand the details of each receptor in order to properly exploit them therapeutically.
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70
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Halim A, Hay DL. The role of glutamic acid 73 in adrenomedullin interactions with rodent AM2 receptors. Peptides 2012; 36:137-41. [PMID: 22546239 DOI: 10.1016/j.peptides.2012.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 04/13/2012] [Accepted: 04/13/2012] [Indexed: 11/22/2022]
Abstract
Adrenomedullin (AM) is a peptide, which is important for vascular development. There is much interest in the clinical potential of its receptors. The mode of AM binding to its receptors is poorly understood. Previous studies have identified amino acid Glu74, which is found in the receptor activity-modifying protein (RAMP3) subunit of the AM(2) receptor as important for high affinity AM interactions with this receptor. Its reciprocal residue in RAMP1 (Trp) impedes AM interactions in the closely related human calcitonin gene-related peptide (CGRP) receptor. The Glu is conserved in RAMP3 across species, supporting its role in contributing to AM binding. We mutated this residue in rat and mouse RAMP3 to Ala, Lys and Trp to determine its function in rodent AM(2) receptors. Only the Trp substitution in mouse RAMP3 produced a substantial reduction in AM potency. However, mutation of the Lys found in rat RAMP1 to Glu enhanced AM potency. Although Glu is highly conserved in RAMP3, this work suggests that it may only make a small or indirect contribution to AM interactions. Nevertheless, the equivalent amino acid in RAMP1 may serve to impair high affinity AM interactions.
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Affiliation(s)
- Angela Halim
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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