1
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Humbert A, Lefebvre R, Nawrot M, Caussy C, Rieusset J. Calcium signalling in hepatic metabolism: Health and diseases. Cell Calcium 2023; 114:102780. [PMID: 37506596 DOI: 10.1016/j.ceca.2023.102780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 07/06/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023]
Abstract
The flexibility between the wide array of hepatic functions relies on calcium (Ca2+) signalling. Indeed, Ca2+ is implicated in the control of many intracellular functions as well as intercellular communication. Thus, hepatocytes adapt their Ca2+ signalling depending on their nutritional and hormonal environment, leading to opposite cellular functions, such as glucose storage or synthesis. Interestingly, hepatic metabolic diseases, such as obesity, type 2 diabetes and non-alcoholic fatty liver diseases, are associated with impaired Ca2+ signalling. Here, we present the hepatocytes' toolkit for Ca2+ signalling, complete with regulation systems and signalling pathways activated by nutrients and hormones. We further discuss the current knowledge on the molecular mechanisms leading to alterations of Ca2+ signalling in hepatic metabolic diseases, and review the literature on the clinical impact of Ca2+-targeting therapeutics.
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Affiliation(s)
- Alexandre Humbert
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France
| | - Rémy Lefebvre
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France
| | - Margaux Nawrot
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France
| | - Cyrielle Caussy
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France; Département Endocrinologie, Diabète et Nutrition, Hospices Civils de Lyon, Hôpital Lyon Sud, Pierre-Bénite, France
| | - Jennifer Rieusset
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France.
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2
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Gao J, Li H, Xu H, Liu Y, Cai M, Shi Y, Zhang J, Wang H. High glucose-induced glucagon resistance and membrane distribution of GCGR revealed by super-resolution imaging. iScience 2023; 26:105967. [PMID: 36824278 PMCID: PMC9941209 DOI: 10.1016/j.isci.2023.105967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/29/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
The glucagon receptor (GCGR) is a member of the class B G protein-coupled receptor family. Many research works have been carried out on GCGR structure, glucagon signaling pathway, and GCGR antagonists. However, the expression and fine distribution of GCGR proteins in response to glucagon under high glucose remain unclear. Using direct stochastic optical reconstruction microscopy (dSTORM) imaging, nanoscale GCGR clusters were observed on HepG2 cell membranes, and high glucose promoted GCGR expression and the formation of more and larger clusters. Moreover, glucagon stimulation under high glucose did not inhibit GCGR levels as significantly as that under low glucose and did not increase the downstream cyclic 3,5'-adenosine monophosphate-protein kinase A (cAMP-PKA) signal, and there were still large-size clusters on the membranes, indicating that high glucose induced glucagon resistance. In addition, high glucose induced stronger glucagon resistance in hepatoma cells compared with hepatic cells. Our work will pave a way to further our understanding of the pathogenesis of diabetes and develop more effective drugs targeting GCGR.
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Affiliation(s)
- Jing Gao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China,Corresponding author
| | - Hongru Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China,University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Haijiao Xu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China
| | - Yong Liu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China
| | - Mingjun Cai
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China
| | - Yan Shi
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China
| | - Jingrui Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China
| | - Hongda Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Research Center of Biomembranomics, Changchun, Jilin 130022, China,University of Science and Technology of China, Hefei, Anhui 230027, China,Laboratory for Marine Biology and Biotechnology, Qing dao National Laboratory for Marine Science and Technology, Wenhai Road, Aoshanwei, Jimo, Qingdao, Shandong 266237, China,Corresponding author
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3
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Tomar M, Somvanshi PR, Kareenhalli V. Physiological significance of bistable circuit design in metabolic homeostasis: role of integrated insulin-glucagon signalling network. Mol Biol Rep 2022; 49:5017-5028. [DOI: 10.1007/s11033-022-07175-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
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4
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Agasid MT, Sørensen L, Urner LH, Yan J, Robinson CV. The Effects of Sodium Ions on Ligand Binding and Conformational States of G Protein-Coupled Receptors-Insights from Mass Spectrometry. J Am Chem Soc 2021; 143:4085-4089. [PMID: 33711230 PMCID: PMC7995251 DOI: 10.1021/jacs.0c11837] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
The use of mass spectrometry
to investigate proteins is now well
established and provides invaluable information for both soluble and
membrane protein assemblies. Maintaining transient noncovalent interactions
under physiological conditions, however, remains challenging. Here,
using nanoscale electrospray ionization emitters, we establish conditions
that enable mass spectrometry of two G protein-coupled receptors (GPCR)
from buffers containing high concentrations of sodium ions. For the
Class A GPCR, the adenosine 2A receptor, we observe ligand-induced
changes to sodium binding of the receptor at the level of individual
sodium ions. We find that antagonists promote sodium binding while
agonists attenuate sodium binding. These findings are in line with
high-resolution X-ray crystallography wherein only inactive conformations
retain sodium ions in allosteric binding pockets. For the glucagon
receptor (a Class B GPCR) we observed enhanced ligand binding in electrospray
buffers containing high concentrations of sodium, as opposed to ammonium
acetate buffers. A combination of native and -omics mass spectrometry
revealed the presence of a lipophilic negative allosteric modulator.
These experiments highlight the advantages of implementing native
mass spectrometry, from electrospray buffers containing high concentrations
of physiologically relevant salts, to inform on allosteric ions or
ligands with the potential to define their roles on GPCR function.
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Affiliation(s)
- Mark T Agasid
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Lars Sørensen
- Global Research Technologies, Novo Nordisk A/S, Novo Nordisk Park, Måløv 2760, Denmark
| | - Leonhard H Urner
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Jun Yan
- Global Research Technologies, Novo Nordisk A/S, Novo Nordisk Park, Måløv 2760, Denmark
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
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5
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Hilger D, Kumar KK, Hu H, Pedersen MF, O'Brien ES, Giehm L, Jennings C, Eskici G, Inoue A, Lerch M, Mathiesen JM, Skiniotis G, Kobilka BK. Structural insights into differences in G protein activation by family A and family B GPCRs. Science 2020; 369:369/6503/eaba3373. [PMID: 32732395 DOI: 10.1126/science.aba3373] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 06/17/2020] [Indexed: 01/06/2023]
Abstract
Family B heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) play important roles in carbohydrate metabolism. Recent structures of family B GPCR-Gs protein complexes reveal a disruption in the α-helix of transmembrane segment 6 (TM6) not observed in family A GPCRs. To investigate the functional impact of this structural difference, we compared the structure and function of the glucagon receptor (GCGR; family B) with the β2 adrenergic receptor (β2AR; family A). We determined the structure of the GCGR-Gs complex by means of cryo-electron microscopy at 3.1-angstrom resolution. This structure shows the distinct break in TM6. Guanosine triphosphate (GTP) turnover, guanosine diphosphate release, GTP binding, and G protein dissociation studies revealed much slower rates for G protein activation by the GCGR compared with the β2AR. Fluorescence and double electron-electron resonance studies suggest that this difference is due to the inability of agonist alone to induce a detectable outward movement of the cytoplasmic end of TM6.
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Affiliation(s)
- Daniel Hilger
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | - Kaavya Krishna Kumar
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | - Hongli Hu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA.,Department of Structural Biology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | | | - Evan S O'Brien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | - Lise Giehm
- Zealand Pharma A/S, Sydmarken 11, Søborg 2860, Denmark
| | - Christine Jennings
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Gözde Eskici
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA.,Department of Structural Biology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Michael Lerch
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | | | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA. .,Department of Structural Biology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA.,Department of Photon Science, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA.
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6
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Chabenne JR, Mroz PA, Mayer JP, DiMarchi RD. Structural Refinement of Glucagon for Therapeutic Use. J Med Chem 2019; 63:3447-3460. [PMID: 31774682 DOI: 10.1021/acs.jmedchem.9b01493] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Glucagon counters insulin's effects on glucose metabolism and serves as a rescue medicine in the treatment of hypoglycemia. Acute hypoglycemia, a common occurrence in insulin-dependent diabetes, is the central obstacle to correcting high blood glucose, a primary cause of long-term microvascular complications. As a result, there has been a resurgence of interest in improved glucagon therapy, including nonconventional liquid formulations, alternative routes of administration, and novel analogs with optimized biophysical properties. These options collectively minimize the complexity of glucagon delivery and enable its application in ways not feasible with conventional emergency rescue kits. These advances have indirectly promoted the integrated use of glucagon agonism with other hormones in a manner that runs counter to the long-standing pursuit of glucagon antagonism. This review summarizes novel approaches to glucagon optimization, methods with potential application to the broader family of therapeutic peptides, where biophysical challenges may be encountered.
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Affiliation(s)
- Joseph R Chabenne
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
| | - Piotr A Mroz
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John P Mayer
- MCD Biology, University of Colorado, Boulder, Colorado 80309, United States
| | - Richard D DiMarchi
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States.,Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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7
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Stimple SD, Kalyoncu S, Desai AA, Mogensen JE, Spang LT, Asgreen DJ, Staby A, Tessier PM. Sensitive detection of glucagon aggregation using amyloid fibril‐specific antibodies. Biotechnol Bioeng 2019; 116:1868-1877. [DOI: 10.1002/bit.26994] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 04/03/2019] [Accepted: 04/11/2019] [Indexed: 02/05/2023]
Affiliation(s)
- Samuel D. Stimple
- Department of Pharmaceutical Sciences, Biointerfaces InstituteUniversity of MichiganAnn Arbor MI
- Department of Chemical Engineering, Biointerfaces InstituteUniversity of MichiganAnn Arbor MI
| | - Sibel Kalyoncu
- Isermann Department of Chemical & Biological Engineering, Center for Biotechnology & Interdisciplinary StudiesRensselaer Polytechnic InstituteTroy NY
| | - Alec A. Desai
- Department of Chemical Engineering, Biointerfaces InstituteUniversity of MichiganAnn Arbor MI
| | | | - Lotte T. Spang
- New Product Introduction, Product SupplyNovo Nordisk A/SCopenhagen Denmark
| | - Désirée J. Asgreen
- New Product Introduction, Product SupplyNovo Nordisk A/SCopenhagen Denmark
| | - Arne Staby
- CMC Development, R&DNovo Nordisk A/SCopenhagen Denmark
| | - Peter M. Tessier
- Department of Pharmaceutical Sciences, Biointerfaces InstituteUniversity of MichiganAnn Arbor MI
- Department of Chemical Engineering, Biointerfaces InstituteUniversity of MichiganAnn Arbor MI
- Department of Biomedical Engineering, Biointerfaces InstituteUniversity of MichiganAnn Arbor MI
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8
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Petersen KM, Bøgevig S, Holst JJ, Knop FK, Christensen MB. Hemodynamic Effects of Glucagon: A Literature Review. J Clin Endocrinol Metab 2018; 103:1804-1812. [PMID: 29546411 DOI: 10.1210/jc.2018-00050] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/07/2018] [Indexed: 02/02/2023]
Abstract
CONTEXT Glucagon's effects on hemodynamic parameters, most notably heart rate and cardiac contractility, are often overlooked. The glucagon receptor is a central target in novel and anticipated type 2 diabetes therapies, and hemodynamic consequences of glucagon signaling have therefore become increasingly important. In this review, we summarize and evaluate published studies on glucagon pharmacology with a focus on clinical hemodynamic effects in humans. EVIDENCE ACQUISITION PubMed, Embase, and the Cochrane Library were searched for clinical studies concerning hemodynamic effects of glucagon (no year restriction). Papers reporting effects of a defined glucagon dose on any hemodynamic parameter were included. Reference searches were conducted in retrieved articles. EVIDENCE SYNTHESIS Hemodynamic effects of glucagon have been investigated mainly in cohort studies of patients suffering from heart failure receiving large glucagon bolus injections. The identified studies had shortcomings related to restricted patient groups, lack of a control group, randomization, or blinding. We identified no properly conducted randomized clinical trials. The majority of human studies report stimulating effects of pharmacological glucagon doses on heart rate, cardiac contractility, and blood pressure. The effects were characterized by short duration, interindividual variation, and rapid desensitization. Some studies reported no measurable effects of glucagon. CONCLUSIONS The level of evidence regarding hemodynamic effects of glucagon is low, and observations in published studies are inconsistent. Actual effects, interindividual variation, dose-response relationships, and possible long-term effects of supraphysiological glucagon levels warrant further investigation.
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Affiliation(s)
- Kasper Meidahl Petersen
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Søren Bøgevig
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip Krag Knop
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, University of Copenhagen, Copenhagen, Denmark
- Faculty of Health and Medical Sciences, Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel Bring Christensen
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
- Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, University of Copenhagen, Copenhagen, Denmark
- Faculty of Health and Medical Sciences, Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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9
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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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10
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Mroz PA, Perez-Tilve D, Liu F, Gelfanov V, DiMarchi RD, Mayer JP. Pyridyl-alanine as a Hydrophilic, Aromatic Element in Peptide Structural Optimization. J Med Chem 2016; 59:8061-7. [PMID: 27509198 DOI: 10.1021/acs.jmedchem.6b00840] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Glucagon (Gcg) 1 serves a seminal physiological role in buffering against hypoglycemia, but its poor biophysical properties severely complicate its medicinal use. We report a series of novel glucagon analogues of enhanced aqueous solubility and stability at neutral pH, anchored by Gcg[Aib16]. Incorporation of 3- and 4-pyridyl-alanine (3-Pal and 4-Pal) enhanced aqueous solubility of glucagon while maintaining biological properties. Relative to native hormone, analogue 9 (Gcg[3-Pal6,10,13, Aib16]) demonstrated superior biophysical character, better suitability for medicinal purposes, and comparable pharmacology against insulin-induced hypoglycemia in rats and pigs. Our data indicate that Pal is a versatile surrogate to natural aromatic amino acids and can be employed as an alternative or supplement with isoelectric adjustment to refine the biophysical character of peptide drug candidates.
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Affiliation(s)
- Piotr A Mroz
- Department of Chemistry, Indiana University , 800 East Kirkwood, Bloomington, Indiana 47405 United States
| | - Diego Perez-Tilve
- Department of Medicine, Metabolic Diseases Institute, University of Cincinnati , Cincinnati, Ohio 45267 United States
| | - Fa Liu
- Novo Nordisk Research Center , Indianapolis, Indiana 46241, United States
| | - Vasily Gelfanov
- Novo Nordisk Research Center , Indianapolis, Indiana 46241, United States
| | - Richard D DiMarchi
- Department of Chemistry, Indiana University , 800 East Kirkwood, Bloomington, Indiana 47405 United States.,Novo Nordisk Research Center , Indianapolis, Indiana 46241, United States
| | - John P Mayer
- Novo Nordisk Research Center , Indianapolis, Indiana 46241, United States
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11
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Singh K, Senthil V, Arokiaraj AWR, Leprince J, Lefranc B, Vaudry D, Allam AA, Ajarem J, Chow BKC. Structure-Activity Relationship Studies of N- and C-Terminally Modified Secretin Analogs for the Human Secretin Receptor. PLoS One 2016; 11:e0149359. [PMID: 26930505 PMCID: PMC4773067 DOI: 10.1371/journal.pone.0149359] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 01/03/2016] [Indexed: 11/18/2022] Open
Abstract
The pleiotropic role of human secretin (hSCT) validates its potential use as a therapeutic agent. Nevertheless, the structure of secretin in complex with its receptor is necessary to develop a suitable therapeutic agent. Therefore, in an effort to design a three-dimensional virtual homology model and identify a peptide agonist and/or antagonist for the human secretin receptor (hSR), the significance of the primary sequence of secretin peptides in allosteric binding and activation was elucidated using virtual docking, FRET competitive binding and assessment of the cAMP response. Secretin analogs containing various N- or C-terminal modifications were prepared based on previous findings of the role of these domains in receptor binding and activation. These analogs exhibited very low or no binding affinity in a virtual model, and were found to neither exhibit in vitro binding nor agonistic or antagonistic properties. A parallel analysis of the analogs in the virtual model and in vitro studies revealed instability of these peptide analogs to bind and activate the receptor.
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Affiliation(s)
- Kailash Singh
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Vijayalakshmi Senthil
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | | | - Jérôme Leprince
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Neurotrophic Factors and Neuronal Differentiation Team, Inserm U982, Associated International Laboratory Samuel de Champlain, Regional Platform for Cell Imaging of Haute-Normandie (PRIMACEN), University of Rouen, Mont-Saint-Aignan, France
| | - Benjamin Lefranc
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Neurotrophic Factors and Neuronal Differentiation Team, Inserm U982, Associated International Laboratory Samuel de Champlain, Regional Platform for Cell Imaging of Haute-Normandie (PRIMACEN), University of Rouen, Mont-Saint-Aignan, France
| | - David Vaudry
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Neurotrophic Factors and Neuronal Differentiation Team, Inserm U982, Associated International Laboratory Samuel de Champlain, Regional Platform for Cell Imaging of Haute-Normandie (PRIMACEN), University of Rouen, Mont-Saint-Aignan, France
| | - Ahmed A. Allam
- Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
- Department of Zoology, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| | - Jamaan Ajarem
- Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Billy K. C. Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
- * E-mail:
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12
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Wu L, Zhai Y, Lu J, Wang Q, Sun F. Expression, purification and preliminary characterization of glucagon receptor extracellular domain. Protein Expr Purif 2013; 89:232-40. [DOI: 10.1016/j.pep.2013.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 04/05/2013] [Accepted: 04/06/2013] [Indexed: 12/13/2022]
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13
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Joiner DM, Ke J, Zhong Z, Xu HE, Williams BO. LRP5 and LRP6 in development and disease. Trends Endocrinol Metab 2013; 24:31-9. [PMID: 23245947 PMCID: PMC3592934 DOI: 10.1016/j.tem.2012.10.003] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 10/09/2012] [Accepted: 10/15/2012] [Indexed: 11/21/2022]
Abstract
Low-density lipoprotein-related receptors 5 and 6 (LRP5/6) are highly homologous proteins with key functions in canonical Wnt signaling. Alterations in the genes encoding these receptors or their interacting proteins are linked to human diseases, and as such they have been a major focus of drug development efforts to treat several human conditions including osteoporosis, cancer, and metabolic disease. Here, we discuss the links between alterations in LRP5/6 and disease, proteins that interact with them, and insights gained into their function from mouse models. We also highlight current drug development related to LRP5/6 as well as how the recent elucidation of their crystal structures may allow further refinement of our ability to target them for therapeutic benefit.
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Affiliation(s)
- Danese M. Joiner
- Center for Skeletal Disease Research, Laboratory of Cell Signaling and Carcinogenesis, Van Andel Research Institute, 333 Bostwick NE, Grand Rapids, MI 49503, USA
| | - Jiyuan Ke
- Center for Structural Biology and Drug Discovery, Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick NE, Grand Rapids, MI 49503, USA
| | - Zhendong Zhong
- Center for Skeletal Disease Research, Laboratory of Cell Signaling and Carcinogenesis, Van Andel Research Institute, 333 Bostwick NE, Grand Rapids, MI 49503, USA
| | - H. Eric Xu
- Center for Structural Biology and Drug Discovery, Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick NE, Grand Rapids, MI 49503, USA
| | - Bart O. Williams
- Center for Skeletal Disease Research, Laboratory of Cell Signaling and Carcinogenesis, Van Andel Research Institute, 333 Bostwick NE, Grand Rapids, MI 49503, USA
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14
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Abstract
Peptide hormones are powerful regulators of various biological processes. To guarantee continuous availability and function, peptide hormone secretion must be tightly coupled to its biosynthesis. A simple but efficient way to provide such regulation is through an autocrine feedback mechanism in which the secreted hormone is "sensed" by its respective receptor and initiates synthesis at the level of transcription and/or translation. Such a secretion-biosynthesis coupling has been demonstrated for insulin; however, because of insulin's unique role as the sole blood glucose-decreasing peptide hormone, this coupling is considered an exception rather than a more generally used mechanism. Here we provide evidence of a secretion-biosynthesis coupling for glucagon, one of several peptide hormones that increase blood glucose levels. We show that glucagon, secreted by the pancreatic α cell, up-regulates the expression of its own gene by signaling through the glucagon receptor, PKC, and PKA, supporting the more general applicability of an autocrine feedback mechanism in regulation of peptide hormone synthesis.
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15
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Krasniqi B, Scruten E, Piller J, Lee J, Napper S. Stability, toxicity and biological activity of retro, inversed and retro-inversed glucagon isomers. J Pept Sci 2012; 18:519-26. [DOI: 10.1002/psc.2429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 05/24/2012] [Accepted: 06/04/2012] [Indexed: 11/12/2022]
Affiliation(s)
- Besnik Krasniqi
- Department of Biochemistry; University of Saskatchewan; Saskatoon Saskatchewan S7N 5E5 Canada
| | - Erin Scruten
- Vaccine and Infectious Disease Organization; University of Saskatchewan; Saskatoon Saskatchewan S7N 5E3 Canada
| | - Jaret Piller
- Department of Biochemistry; University of Saskatchewan; Saskatoon Saskatchewan S7N 5E5 Canada
| | - Jeremy Lee
- Department of Biochemistry; University of Saskatchewan; Saskatoon Saskatchewan S7N 5E5 Canada
| | - Scott Napper
- Department of Biochemistry; University of Saskatchewan; Saskatoon Saskatchewan S7N 5E5 Canada
- Vaccine and Infectious Disease Organization; University of Saskatchewan; Saskatoon Saskatchewan S7N 5E3 Canada
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16
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Ke J, Zhang C, Harikumar KG, Zylstra-Diegel CR, Wang L, Mowry LE, Miller LJ, Williams BO, Xu HE. Modulation of β-catenin signaling by glucagon receptor activation. PLoS One 2012; 7:e33676. [PMID: 22438981 PMCID: PMC3306284 DOI: 10.1371/journal.pone.0033676] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 02/14/2012] [Indexed: 11/18/2022] Open
Abstract
The glucagon receptor (GCGR) is a member of the class B G protein–coupled receptor family. Activation of GCGR by glucagon leads to increased glucose production by the liver. Thus, glucagon is a key component of glucose homeostasis by counteracting the effect of insulin. In this report, we found that in addition to activation of the classic cAMP/protein kinase A (PKA) pathway, activation of GCGR also induced β-catenin stabilization and activated β-catenin–mediated transcription. Activation of β-catenin signaling was PKA-dependent, consistent with previous reports on the parathyroid hormone receptor type 1 (PTH1R) and glucagon-like peptide 1 (GLP-1R) receptors. Since low-density-lipoprotein receptor–related protein 5 (Lrp5) is an essential co-receptor required for Wnt protein mediated β-catenin signaling, we examined the role of Lrp5 in glucagon-induced β-catenin signaling. Cotransfection with Lrp5 enhanced the glucagon-induced β-catenin stabilization and TCF promoter–mediated transcription. Inhibiting Lrp5/6 function using Dickkopf-1(DKK1) or by expression of the Lrp5 extracellular domain blocked glucagon-induced β-catenin signaling. Furthermore, we showed that Lrp5 physically interacted with GCGR by immunoprecipitation and bioluminescence resonance energy transfer assays. Together, these results reveal an unexpected crosstalk between glucagon and β-catenin signaling, and may help to explain the metabolic phenotypes of Lrp5/6 mutations.
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Affiliation(s)
- Jiyuan Ke
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
- * E-mail: (JK); (HEX)
| | - Chenghai Zhang
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Kaleeckal G. Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona, United States of America
| | - Cassandra R. Zylstra-Diegel
- Laboratory of Cell Signaling and Carcinogenesis, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Liren Wang
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Laura E. Mowry
- Laboratory of Cell Signaling and Carcinogenesis, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Laurence J. Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona, United States of America
| | - Bart O. Williams
- Laboratory of Cell Signaling and Carcinogenesis, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - H. Eric Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
- VARI/SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, People's Republic of China
- * E-mail: (JK); (HEX)
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17
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Coopman K, Wallis R, Robb G, Brown AJH, Wilkinson GF, Timms D, Willars GB. Residues within the transmembrane domain of the glucagon-like peptide-1 receptor involved in ligand binding and receptor activation: modelling the ligand-bound receptor. Mol Endocrinol 2011; 25:1804-18. [PMID: 21868452 DOI: 10.1210/me.2011-1160] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The C-terminal regions of glucagon-like peptide-1 (GLP-1) bind to the N terminus of the GLP-1 receptor (GLP-1R), facilitating interaction of the ligand N terminus with the receptor transmembrane domain. In contrast, the agonist exendin-4 relies less on the transmembrane domain, and truncated antagonist analogs (e.g. exendin 9-39) may interact solely with the receptor N terminus. Here we used mutagenesis to explore the role of residues highly conserved in the predicted transmembrane helices of mammalian GLP-1Rs and conserved in family B G protein coupled receptors in ligand binding and GLP-1R activation. By iteration using information from the mutagenesis, along with the available crystal structure of the receptor N terminus and a model of the active opsin transmembrane domain, we developed a structural receptor model with GLP-1 bound and used this to better understand consequences of mutations. Mutation at Y152 [transmembrane helix (TM) 1], R190 (TM2), Y235 (TM3), H363 (TM6), and E364 (TM6) produced similar reductions in affinity for GLP-1 and exendin 9-39. In contrast, other mutations either preferentially [K197 (TM2), Q234 (TM3), and W284 (extracellular loop 2)] or solely [D198 (TM2) and R310 (TM5)] reduced GLP-1 affinity. Reduced agonist affinity was always associated with reduced potency. However, reductions in potency exceeded reductions in agonist affinity for K197A, W284A, and R310A, while H363A was uncoupled from cAMP generation, highlighting critical roles of these residues in translating binding to activation. Data show important roles in ligand binding and receptor activation of conserved residues within the transmembrane domain of the GLP-1R. The receptor structural model provides insight into the roles of these residues.
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Affiliation(s)
- K Coopman
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
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18
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Patterson JT, Day JW, Gelfanov VM, DiMarchi RD. Functional association of the N-terminal residues with the central region in glucagon-related peptides. J Pept Sci 2011; 17:659-66. [PMID: 21661079 DOI: 10.1002/psc.1385] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 04/23/2011] [Accepted: 05/03/2011] [Indexed: 11/09/2022]
Abstract
GLP-1 is an incretin peptide involved in the regulation of glucose metabolism and the glucose-dependent stimulation of insulin secretion. Ex-4 is a paralog of GLP-1 that has comparable GLP-1R potency but extended physiological action. GLP-1 and Ex-4 are helical peptides that share ∼50% sequence homology but differ at several residues, notably the second amino acid which controls susceptibility to DPP-IV cleavage. This single amino acid difference yields divergent receptor potency when studied in the context of the two hormone sequences. Ex-4 uniquely tolerates Gly2 through select amino acid differences in the middle region of the peptide that are absent in GLP-1. We report that substitution of Ex-4 amino acids Glu16, Leu21, and Glu24 to the GLP-1 sequence enabled Gly2 tolerance. The coordination of the N-terminus with these central residues shows an interaction of substantial importance not only to DPP-IV stability but also to receptor activation. Extension of this observation to glucagon-based co-agonist peptides showed different structural requirements for effective communication between the N-terminus and the mid-section of these peptides in achieving high potency agonism at the GLP-1 and GCGRs.
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Affiliation(s)
- James T Patterson
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
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19
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Day JW, Li P, Patterson JT, Chabenne J, Chabenne MD, Gelfanov VM, DiMarchi RD. Charge inversion at position 68 of the glucagon and glucagon-like peptide-1 receptors supports selectivity in hormone action. J Pept Sci 2010; 17:218-25. [DOI: 10.1002/psc.1317] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 09/09/2010] [Accepted: 09/20/2010] [Indexed: 02/05/2023]
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20
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Dickson L, Finlayson K. VPAC and PAC receptors: From ligands to function. Pharmacol Ther 2008; 121:294-316. [PMID: 19109992 DOI: 10.1016/j.pharmthera.2008.11.006] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Accepted: 11/18/2008] [Indexed: 02/03/2023]
Abstract
Vasoactive intestinal peptide (VIP) and the pituitary adenylate cyclase activating polypeptides (PACAPs) share 68% identity at the amino acid level and belong to the secretin peptide family. Following the initial discovery of VIP almost four decades ago a substantial amount of knowledge has been presented describing the mechanisms of action, distribution and pleiotropic functions of these related peptides. It is now known that the physiological actions of these widely distributed peptides are produced through activation of three common G-protein coupled receptors (VPAC(1), VPAC(2) and PAC(1)R) which preferentially stimulate adenylate cyclase and increase intracellular cAMP, although stimulation of other intracellular messengers, including calcium and phospholipase D, has been reported. Using a range of in vitro and in vivo approaches, including cell-based functional assays, transgenic animals and rodent models of disease, VPAC/PAC receptor activation has been associated with numerous physiological processes (e.g. control of circadian rhythms) and clinical conditions (e.g. pulmonary hypertension), which underlies on-going research efforts and makes these peptides and their cognate receptors attractive targets for the pharmaceutical industry. However, despite the considerable interest in VPAC/PAC receptors and the processes which they mediate, there is still a paucity of selective and available, non-peptide ligands, which has hindered further advances in this field both at the basic research and clinical level. This review summarises the current knowledge of VIP/PACAP and the VPAC/PAC receptors with regard to their distribution, pharmacology, signalling pathways, splice variants and finally, the utility of animal models in exploring their physiological roles.
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Affiliation(s)
- Louise Dickson
- Centre for Integrative Physiology, University of Edinburgh, EH8 9XD, UK
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21
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Bharucha KN, Tarr P, Zipursky SL. A glucagon-like endocrine pathway in Drosophila modulates both lipid and carbohydrate homeostasis. ACTA ACUST UNITED AC 2008; 211:3103-10. [PMID: 18805809 PMCID: PMC2714167 DOI: 10.1242/jeb.016451] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The regulation of energy homeostasis is fundamental to all organisms. The Drosophila fat body serves as a repository for both triglycerides and glycogen, combining the energy storage functions of mammalian adipose and hepatic tissues, respectively. Here we show that mutation of the Drosophila adipokinetic hormone receptor (AKHR), a functional analog of the mammalian glucagon receptor, leads to abnormal accumulation of both lipid and carbohydrate. As a consequence of their obese phenotypes, AKHR mutants are markedly starvation resistant. We show that AKHR is expressed in the fat body, and, intriguingly, in a subset of gustatory neurons that mediate sweet taste. Genetic rescue experiments establish that the metabolic phenotypes arise exclusively from the fat body AKHR expression. Behavioral experiments demonstrate that AKHR mutants are neither sedentary nor hyperphagic, suggesting the metabolic abnormalities derive from a genetic propensity to retain energy stores. Taken together, our results indicate that a single endocrine pathway contributes to both lipid and carbohydrate catabolism in the Drosophila fat body.
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Affiliation(s)
- K N Bharucha
- Department of Pediatrics and Pharmacology, University of Texas Southwestern Medical School, Dallas, Texas 75390, USA.
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22
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Wang J, Wang Y, Li X, Li J, Leung F. Cloning, Tissue Distribution, and Functional Characterization of Chicken Glucagon Receptor. Poult Sci 2008; 87:2678-88. [DOI: 10.3382/ps.2008-00260] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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23
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Lin F, Wang R. Molecular modeling of the three-dimensional structure of GLP-1R and its interactions with several agonists. J Mol Model 2008; 15:53-65. [PMID: 18941807 DOI: 10.1007/s00894-008-0372-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 09/22/2008] [Indexed: 01/18/2023]
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) is a promising molecular target for developing drugs treating type 2 diabetes. We have predicted the complete three-dimensional structure of GLP-1R and the binding modes of several GLP-1R agonists, including GLP-1, Boc5, and Cpd1, through a combination of homology modeling, molecular docking, and long-time molecular dynamics simulation on a lipid bilayer. Our model can reasonably interpret the results of a number of mutation experiments regarding GLP-1R as well as the successful modification to GLP-1 by Liraglutide. Our model is also validated by a recently revealed crystal structure of the extracellular domain of GLP-1R. An activation mechanism of GLP-1R agonists is proposed based on the principal component analysis and normal mode analysis on our predicted GLP-1R structure. Before the complete structure of GLP-1R is determined through experimental means, our model may serve as a valuable reference for characterizing the interactions between GLP-1R and its agonists.
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Affiliation(s)
- Fu Lin
- State Key Laboratory of Bioorganic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, People's Republic of China
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24
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Unson CG. Merrifield laboratory: Last member standing. Biopolymers 2008; 90:243-4. [DOI: 10.1002/bip.20942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Imming P, Sinning C, Meyer A. Drugs, their targets and the nature and number of drug targets. Nat Rev Drug Discov 2006; 5:821-34. [PMID: 17016423 DOI: 10.1038/nrd2132] [Citation(s) in RCA: 484] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
What is a drug target? And how many such targets are there? Here, we consider the nature of drug targets, and by classifying known drug substances on the basis of the discussed principles we provide an estimation of the total number of current drug targets.
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Affiliation(s)
- Peter Imming
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany.
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26
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Abstract
Class B G protein-coupled receptors (GPCRs) regulate a wide range of endocrine and neuroendocrine functions and are endogenously stimulated by moderately large peptide hormones. Current evidence suggests that the carboxyl termini of cognate peptides bind to the amino terminus of their G protein-coupled receptors (GPCRs) and that the peptides' amino terminal segments then dock to the heptahelical receptor portion to induce signaling. In this issue of Molecular Pharmacology, Dong et al. (p. 206) propose an alternative model of ligand-induced class B GPCR activation. Based primarily on studies with the secretin receptor, a prototype class B family member, they provide evidence that the endogenous peptide hormone does not function as an activator per se. Instead, this hormone (secretin) exposes a hidden, built-in agonist epitope that is present within the amino terminus of its target GPCR. Isolated oligopeptide fragments containing this epitope act as full agonists on the secretin receptor despite their lack of amino acid homology with the secretin hormone. These nonconventional agonists can be minimized to tripeptide molecules and still maintain biological activity. The study to be discussed introduces a novel paradigm of class B GPCR function, and may facilitate the elusive goal of finding small molecule agonist drugs for this therapeutically attractive group of receptors.
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Affiliation(s)
- Martin Beinborn
- Molecular Pharmacology Research Center, Molecular Cardiology Research Institute, Tufts-New England Medical Center, 15 Kneeland Street, Boston, MA 02111, USA.
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27
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Pan CQ, Buxton JM, Yung SL, Tom I, Yang L, Chen H, MacDougall M, Bell A, Claus TH, Clairmont KB, Whelan JP. Design of a long acting peptide functioning as both a glucagon-like peptide-1 receptor agonist and a glucagon receptor antagonist. J Biol Chem 2006; 281:12506-15. [PMID: 16505481 DOI: 10.1074/jbc.m600127200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The closely related peptides glucagon-like peptide (GLP-1) and glucagon have opposing effects on blood glucose. GLP-1 induces glucose-dependent insulin secretion in the pancreas, whereas glucagon stimulates gluconeogenesis and glycogenolysis in the liver. The identification of a hybrid peptide acting as both a GLP-1 agonist and a glucagon antagonist would provide a novel approach for the treatment of type 2 diabetes. Toward this end a series of hybrid peptides made up of glucagon and either GLP-1 or exendin-4, a GLP-1 agonist, was engineered. Several peptides that bind to both the GLP-1 and glucagon receptors were identified. The presence of glucagon sequence at the N terminus removed the dipeptidylpeptidase IV cleavage site and increased plasma stability compared with GLP-1. Targeted mutations were incorporated into the optimal dual-receptor binding peptide to identify a peptide with the highly novel property of functioning as both a GLP-1 receptor agonist and a glucagon receptor antagonist. To overcome the short half-life of this mutant peptide in vivo, while retaining dual GLP-1 agonist and glucagon antagonist activities, site-specific attachment of long chained polyethylene glycol (PEGylation) was pursued. PEGylation at the C terminus retained the in vitro activities of the peptide while dramatically prolonging the duration of action in vivo. Thus, we have generated a novel dual-acting peptide with potential for development as a therapeutic for type 2 diabetes.
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Affiliation(s)
- Clark Q Pan
- Department of Biotechnology, Bayer HealthCare, California 94701, USA
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28
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Kristiansen K. Molecular mechanisms of ligand binding, signaling, and regulation within the superfamily of G-protein-coupled receptors: molecular modeling and mutagenesis approaches to receptor structure and function. Pharmacol Ther 2004; 103:21-80. [PMID: 15251227 DOI: 10.1016/j.pharmthera.2004.05.002] [Citation(s) in RCA: 392] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The superfamily of G-protein-coupled receptors (GPCRs) could be subclassified into 7 families (A, B, large N-terminal family B-7 transmembrane helix, C, Frizzled/Smoothened, taste 2, and vomeronasal 1 receptors) among mammalian species. Cloning and functional studies of GPCRs have revealed that the superfamily of GPCRs comprises receptors for chemically diverse native ligands including (1) endogenous compounds like amines, peptides, and Wnt proteins (i.e., secreted proteins activating Frizzled receptors); (2) endogenous cell surface adhesion molecules; and (3) photons and exogenous compounds like odorants. The combined use of site-directed mutagenesis and molecular modeling approaches have provided detailed insight into molecular mechanisms of ligand binding, receptor folding, receptor activation, G-protein coupling, and regulation of GPCRs. The vast majority of family A, B, C, vomeronasal 1, and taste 2 receptors are able to transduce signals into cells through G-protein coupling. However, G-protein-independent signaling mechanisms have also been reported for many GPCRs. Specific interaction motifs in the intracellular parts of these receptors allow them to interact with scaffold proteins. Protein engineering techniques have provided information on molecular mechanisms of GPCR-accessory protein, GPCR-GPCR, and GPCR-scaffold protein interactions. Site-directed mutagenesis and molecular dynamics simulations have revealed that the inactive state conformations are stabilized by specific interhelical and intrahelical salt bridge interactions and hydrophobic-type interactions. Constitutively activating mutations or agonist binding disrupts such constraining interactions leading to receptor conformations that associates with and activate G-proteins.
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Affiliation(s)
- Kurt Kristiansen
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.
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29
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McNally T, Grihalde ND, Pederson TM, Ogiela CA, Djuric SW, Collins CA, Lin CW, Reilly RM. Cloning and characterization of the glucagon receptor from cynomologous monkey. Peptides 2004; 25:1171-8. [PMID: 15245877 DOI: 10.1016/j.peptides.2004.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 05/04/2004] [Accepted: 05/04/2004] [Indexed: 10/26/2022]
Abstract
The glucagon receptor was cloned from cynolomologous monkey. A frame-shift mutation at the 3' end of the monkey transcript results in a C-terminal extension of 14 amino acids. This extension is not observed in either the human or rodent glucagon receptors. Monkey glucagon receptor was expressed in CHO cells, either with (mkGCGR) or without (mkGCGRDelta14) the 14-amino acid C-terminal extension to approximate the human receptor. Both forms of the monkey receptor bound glucagon with similar affinity and showed glucagon-stimulated cAMP production, however the full-length form of the monkey receptor (mkGCGR) was less sensitive to glucagon in its ability to stimulate cAMP than the shortened form (mkGCGRDelta14). PCR of genomic DNA from baboon and rhesus monkeys suggests that they express a form of the receptor similar to that of cynomologous monkey, while in chimpanzee, the receptor is similar to the human form.
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Affiliation(s)
- Teresa McNally
- Metabolic Disease Research, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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30
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Chow BKC, Moon TW, Hoo RLC, Yeung CM, Müller M, Christos PJ, Mojsov S. Identification and characterization of a glucagon receptor from the goldfish Carassius auratus: implications for the evolution of the ligand specificity of glucagon receptors in vertebrates. Endocrinology 2004; 145:3273-88. [PMID: 15033912 DOI: 10.1210/en.2003-0597] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The structural basis of ligand selectivity of G protein-coupled receptors for metabolic hormones has been an area of intense investigation, and yet it remains unresolved. One approach to delineating the mechanism of ligand-receptor interactions is to compare the ligand specificities of receptors expressed in species that emerged at different times within vertebrate evolution. In this paper we describe the isolation, functional, and phylogenetic characterization of the glucagon receptor from the goldfish Carassius auratus (Teleostei, order Cypriniformes), and compare its ligand specificity with that of the homologous rat receptor. Goldfish (gf) glucagon stimulated glucose production in a dose-dependent manner from isolated goldfish hepatocytes, resulting in 5-fold increase at 1 microm. The goldfish glucagon receptor (gfGlucR) shares 56, 51, 50, and 52% amino acid identities with frog Rana tigrina regulosa, mouse, rat, and human glucagon receptors, respectively. In competitive binding experiments, the recombinant gfGlucR displays high affinity toward goldfish, zebrafish, and human glucagons (IC(50) = 0.6, 9, and 13 nm, respectively) but not toward goldfish glucagon-like peptide-1 or human glucagon-like peptide-1 (7-36) amide. Whereas both goldfish and human glucagons stimulated dose-dependent increases in intracellular cAMP through the recombinant gfGlucR, the recombinant rat GlucR interacted only with human glucagon, analogous to the specificity of the previously characterized glucagon receptor from the frog R. tigrina regulosa. Our results demonstrate that the binding pocket of gfGlucR can accommodate a broad range of glucagon structures and that in the frogs and mammals, there is a structural switch to a more restrictive conformation of glucagon receptors.
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Affiliation(s)
- Billy K C Chow
- Department of Zoology, University of Hong Kong, Hong Kong
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31
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Sapse AM, Lawton S, Rothchild R, Unson CG. An ab initio study of non-peptide glucagon receptor antagonists. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/j.theochem.2003.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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