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Bloxham CJ, Hulme KD, Fierro F, Fercher C, Pegg CL, O'Brien SL, Foster SR, Short KR, Furness SGB, Reichelt ME, Niv MY, Thomas WG. Cardiac human bitter taste receptors contain naturally occurring variants that alter function. Biochem Pharmacol 2024; 219:115932. [PMID: 37989413 DOI: 10.1016/j.bcp.2023.115932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 10/26/2023] [Accepted: 11/16/2023] [Indexed: 11/23/2023]
Abstract
Bitter taste receptors (T2R) are a subfamily of G protein-coupled receptors that enable humans to detect aversive and toxic substances. The ability to discern bitter compounds varies between individuals and is attributed mainly to naturally occurring T2R polymorphisms. T2Rs are also expressed in numerous non-gustatory tissues, including the heart, indicating potential contributions to cardiovascular physiology. In this study. T2Rs that have previously been identified in human cardiac tissues (T2Rs - 10, 14, 30, 31, 46 and 50) and their naturally occurring polymorphisms were functionally characterised. The ligand-dependent signaling responses of some T2R variants were completely abolished (T2R30 Leu252 and T2R46 Met228), whereas other receptor variants had moderate changes in their maximal response, but not potency, relative to wild type. Using a cAMP fluorescent biosensor, we reveal the productive coupling of T2R14, but not the T2R14 Phe201 variant, to endogenous Gαi. Modeling revealed that these variants resulted in altered interactions that generally affected ligand binding (T2R30 Leu252) or Gα protein interactions (T2R46 Met228 and T2R14 Phe201), rather than receptor structural stability. Interestingly, this study is the first to show a difference in signaling for T2R50 Tyr203 (rs1376251) which has been associated with cardiovascular disease. The observation of naturally occurring functional variation in the T2Rs with the greatest expression in the heart is important, as their discovery should prove useful in deciphering the role of T2Rs within the cardiovascular system.
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Affiliation(s)
- Conor J Bloxham
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, QLD, Australia; Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, Germany
| | - Katina D Hulme
- School of Chemistry and Molecular Biosciences, Faculty of Science, University of Queensland, QLD, Australia; Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Fabrizio Fierro
- Institute of Biochemistry, Food Science and Nutrition, The Hebrew University of Jerusalem, Israel
| | - Christian Fercher
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, QLD, Australia
| | - Cassandra L Pegg
- School of Chemistry and Molecular Biosciences, Faculty of Science, University of Queensland, QLD, Australia
| | - Shannon L O'Brien
- Institute of Metabolism and Systems Research, University of Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Simon R Foster
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, QLD, Australia; QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Kirsty R Short
- School of Chemistry and Molecular Biosciences, Faculty of Science, University of Queensland, QLD, Australia
| | - Sebastian G B Furness
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, QLD, Australia; Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Melissa E Reichelt
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, QLD, Australia
| | - Masha Y Niv
- Institute of Biochemistry, Food Science and Nutrition, The Hebrew University of Jerusalem, Israel
| | - Walter G Thomas
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, QLD, Australia.
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Ringuet MT, Koo A, Furness SGB, McDougall SJ, Furness JB. Sites and mechanisms of action of colokinetics at dopamine, ghrelin and serotonin receptors in the rodent lumbosacral defecation centre. J Physiol 2023; 601:5195-5211. [PMID: 37772438 PMCID: PMC10952827 DOI: 10.1113/jp285217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 09/13/2023] [Indexed: 09/30/2023] Open
Abstract
Agonists of dopamine D2 receptors (D2R), 5-hydroxytryptamine (5-HT, serotonin) receptors (5-HTR) and ghrelin receptors (GHSR) activate neurons in the lumbosacral defecation centre, and act as 'colokinetics', leading to increased propulsive colonic motility, in vivo. In the present study, we investigated which neurons in the lumbosacral defecation centre express the receptors and whether dopamine, serotonin and ghrelin receptor agonists act on the same lumbosacral preganglionic neurons (PGNs). We used whole cell electrophysiology to record responses from neurons in the lumbosacral defecation centre, following colokinetic application, and investigated their expression profiles and the chemistries of their neural inputs. Fluorescence in situ hybridisation revealed Drd2, Ghsr and Htr2C transcripts were colocalised in lumbosacral PGNs of mice, and immunohistochemistry showed that these neurons have closely associated tyrosine hydroxylase and 5-HT boutons. Previous studies showed that they do not receive ghrelin inputs. Whole cell electrophysiology in adult mice spinal cord revealed that dopamine, serotonin, α-methylserotonin and capromorelin each caused inward, excitatory currents in overlapping populations of lumbosacral PGNs. Furthermore, dopamine caused increased frequency of both IPSCs and EPSCs in a cohort of D2R neurons. Tetrodotoxin blocked the IPSCs and EPSCs, revealing a post-synaptic excitatory action of dopamine. In lumbosacral PGNs of postnatal day 7-14 rats, only dopamine's postsynaptic effects were observed. Furthermore, inward, excitatory currents evoked by dopamine were reduced by the GHSR antagonist, YIL781. We conclude that lumbosacral PGNs are the site where the action of endogenous ligands of D2R and 5-HT2R converge, and that GHSR act as a cis-modulator of D2R expressed by the same neurons. KEY POINTS: Dopamine, 5-hydroxytryptamine (5-HT, serotonin) and ghrelin (GHSR) receptor agonists increase colorectal motility and have been postulated to act at receptors on parasympathetic preganglionic neurons (PGNs) in the lumbosacral spinal cord. We aimed to determine which neurons in the lumbosacral spinal cord express dopamine, serotonin and GHSR receptors, their neural inputs, and whether agonists at these receptors excite them. We show that dopamine, serotonin and ghrelin receptor transcripts are contained in the same PGNs and that these neurons have closely associated tyrosine hydroxylase and serotonin boutons. Whole cell electrophysiology revealed that dopamine, serotonin and GHSR receptor agonists induce an inward excitatory current in overlapping populations of lumbosacral PGNs. Dopamine-induced excitation was reversed by GHSR antagonism. The present study demonstrates that lumbosacral PGNs are the site at which actions of endogenous ligands of dopamine D2 receptors and 5-HT type 2 receptors converge. Ghrelin receptors are functional, but their role appears to be as modulators of dopamine effects at D2 receptors.
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Affiliation(s)
- Mitchell T. Ringuet
- Department of Anatomy & PhysiologyUniversity of MelbourneMelbourneVICAustralia
| | - Ada Koo
- Department of Anatomy & PhysiologyUniversity of MelbourneMelbourneVICAustralia
| | - Sebastian G. B. Furness
- School of Biomedical SciencesUniversity of QueenslandBrisbaneQLDAustralia
- Monash Institute of Pharmaceutical SciencesMelbourneVICAustralia
| | - Stuart J. McDougall
- Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVICAustralia
| | - John B. Furness
- Department of Anatomy & PhysiologyUniversity of MelbourneMelbourneVICAustralia
- Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVICAustralia
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Piper NBC, Whitfield EA, Stewart GD, Xu X, Furness SGB. Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors. Biochem Pharmacol 2022; 202:115115. [PMID: 35671790 DOI: 10.1016/j.bcp.2022.115115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.
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Affiliation(s)
- Noah B C Piper
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Emily A Whitfield
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Gregory D Stewart
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Xiaomeng Xu
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Sebastian G B Furness
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia; Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia.
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4
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Furness JB, Pustovit RV, Syder AJ, Ringuet MT, Yoo EJ, Fanjul A, Wykosky J, Fothergill LJ, Whitfield EA, Furness SGB. Dopamine and ghrelin receptor co-expression and interaction in the spinal defecation centers. Neurogastroenterol Motil 2021; 33:e14051. [PMID: 33264473 DOI: 10.1111/nmo.14051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 10/20/2020] [Accepted: 11/12/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND Dopamine receptor 2 (DRD2) and ghrelin receptor (GHSR1a) agonists both stimulate defecation by actions at the lumbosacral defecation center. Dopamine is in nerve terminals surrounding autonomic neurons of the defecation center, whereas ghrelin is not present in the spinal cord. Dopamine at D2 receptors generally inhibits neurons, but at the defecation center, its effect is excitatory. METHODS In vivo recording of defecation and colorectal propulsion was used to investigate interaction between DRD2 and GHSR1a. Localization studies were used to determine sites of receptor expression in rat and human spinal cord. KEY RESULTS Dopamine, and the DRD2 agonist, quinpirole, directly applied to the lumbosacral cord, caused defecation. The effect of intrathecal dopamine was inhibited by the GHSR1a antagonist, YIL781, given systemically, but YIL781 was not an antagonist at DRD2. The DRD2 agonist, pramipexole, administered systemically caused colorectal propulsion that was prevented when the pelvic nerves were cut. Drd2 and Ghsr were expressed together in autonomic preganglionic neurons at the level of the defecation centers in rat and human. Behaviorally induced defecation (caused by water avoidance stress) was reduced by the DRD2 antagonist, sulpiride. We had previously shown it is reduced by YIL781. CONCLUSIONS AND INFERENCES Our observations imply that dopamine is a transmitter of the defecation pathways whose actions are exerted through interacting dopamine (D2) and ghrelin receptors on lumbosacral autonomic neurons that project to the colorectum. The results explain the excitation by dopamine agonists and the conservation of GHSR1a in the absence of ghrelin.
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Affiliation(s)
- John B Furness
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Vic., Australia
| | - Ruslan V Pustovit
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Vic., Australia
| | - Andrew J Syder
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Mitchell T Ringuet
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Vic., Australia
| | - Eun Ji Yoo
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Andrea Fanjul
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Jill Wykosky
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Linda J Fothergill
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
| | - Emily A Whitfield
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
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Harikumar KG, Coudrat T, Desai AJ, Dong M, Dengler DG, Furness SGB, Christopoulos A, Wootten D, Sergienko EA, Sexton PM, Miller LJ. Discovery of a Positive Allosteric Modulator of Cholecystokinin Action at CCK1R in Normal and Elevated Cholesterol. Front Endocrinol (Lausanne) 2021; 12:789957. [PMID: 34950108 PMCID: PMC8689142 DOI: 10.3389/fendo.2021.789957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
Drugs useful in prevention/treatment of obesity could improve health. Cholecystokinin (CCK) is a key regulator of appetite, working through the type 1 CCK receptor (CCK1R); however, full agonists have not stimulated more weight loss than dieting. We proposed an alternate strategy to target this receptor, while reducing likelihood of side effects and/or toxicity. Positive allosteric modulators (PAMs) with minimal intrinsic agonist activity would enhance CCK action, while maintaining spatial and temporal characteristics of physiologic signaling. This could correct abnormal stimulus-activity coupling observed in a high-cholesterol environment observed in obesity. We utilized high-throughput screening to identify a molecule with this pharmacological profile and studied its basis of action. Compound 1 was a weak partial agonist, with PAM activity to enhance CCK action at CCK1R, but not CCK2R, maintained in both normal and high cholesterol. Compound 1 (10 µM) did not exhibit agonist activity or stimulate internalization of CCK1R. It enhanced CCK activity by slowing the off-rate of bound hormone, increasing its binding affinity. Computational docking of Compound 1 to CCK1R yielded plausible poses. A radioiodinatable photolabile analogue retained Compound 1 pharmacology and covalently labeled CCK1R Thr211, consistent with one proposed pose. Our study identifies a novel, selective, CCK1R PAM that binds to the receptor to enhance action of CCK-8 and CCK-58 in both normal and disease-mimicking high-cholesterol environments. This facilitates the development of compounds that target the physiologic spatial and temporal engagement of CCK1R by CCK that underpins its critical role in metabolic regulation.
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Affiliation(s)
- Kaleeckal G. Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
| | - Thomas Coudrat
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Aditya J. Desai
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
| | - Maoqing Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
| | - Daniela G. Dengler
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, United States
| | - Sebastian G. B. Furness
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Eduard A. Sergienko
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, United States
| | - Patrick M. Sexton
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Laurence J. Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
- *Correspondence: Laurence J. Miller,
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Gupta P, Furness SGB, Bittencourt L, Hare DL, Wookey PJ. Building the case for the calcitonin receptor as a viable target for the treatment of glioblastoma. Ther Adv Med Oncol 2020; 12:1758835920978110. [PMID: 33425026 PMCID: PMC7758865 DOI: 10.1177/1758835920978110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/11/2020] [Indexed: 12/15/2022] Open
Abstract
Researchers are actively seeking novel targeted therapies for the brain tumour glioblastoma (GBM) as the mean survival is less than 15 months. Here we discuss the proposal that the calcitonin receptor (CT Receptor), expressed in 76-86% of patient biopsies, is expressed by both malignant glioma cells and putative glioma stem cells (GSCs), and therefore represents a potential therapeutic target. Forty-two per cent (42%) of high-grade glioma (HGG; representative of GSCs) cell lines express CT Receptor protein. CT Receptors are widely expressed throughout the life cycle of organisms and in some instances promote apoptosis. Which of the common isoforms of the CT Receptor are predominantly expressed is currently unknown, but a functional response to cell stress of the insert-positive isoform is hypothesised. A model for resistant malignancies is one in which chemotherapy plays a direct role in activating quiescent stem cells for replacement of the tumour tissue hierarchy. The putative role that the CT Receptor plays in maintenance of quiescent cancer stem cells is discussed in view of the activation of the Notch-CT Receptor-collagen V axis in quiescent muscle (satellite) stem cells. The pharmacological CT response profiles of four of the HGG cell lines were reported. Both CT responders and non-responders were sensitive to an immunotoxin based on an anti-CT Receptor antibody. The CALCR mRNA exhibits alternative splicing commonly associated with cancer cells, which could result in the atypical pharmacology exhibited by CT non-responders and an explanation of tumour suppression. Due to the inherent instability of CALCR mRNA, analysis of CT Receptor protein in patient samples will lead to improved data for the expression of CT Receptor in GBM and other cancers, and an understanding of the role and activity of the splice variants. This knowledge will aid the effective targeting of this receptor for treatment of GBM.
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Affiliation(s)
- Pragya Gupta
- Department of Medicine (Austin Health, Heidelberg), University of Melbourne, Melbourne, Victoria, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology, Monash University (Parkville), Victoria, Australia
| | - Lucas Bittencourt
- Department of Medicine (Austin Health, Heidelberg), University of Melbourne, Melbourne, Victoria, Australia
| | - David L Hare
- Department of Medicine (Austin Health, Heidelberg), University of Melbourne, Melbourne, Victoria, Australia
| | - Peter J Wookey
- Department of Medicine, University of Melbourne, Level 10, Lance Townsend Building, Austin Health, Studley Road, Heidelberg, Victoria 3084, Australia
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Liu M, Whitfield EA, Fothergill LJ, Furness JB, Wade JD, Furness SGB, Hossain MA. Design, synthesis and characterization of a fluorescently labeled functional analog of full-length human ghrelin. Biochem Biophys Res Commun 2020; 533:559-564. [PMID: 32980116 DOI: 10.1016/j.bbrc.2020.09.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 09/10/2020] [Indexed: 11/17/2022]
Abstract
Human ghrelin receptor (GHSR) is a recognized prospective target in the diagnosis and therapy of multiple cancer types. To gain a better understanding of this receptor signaling system, we have synthesized a novel full-length ghrelin analog that is fluorescently labeled at the side-chain of a C-terminal cysteine extension. This analog exhibited nanomolar affinity and potency for the ghrelin receptor. It shows comparable efficacy with that of endogenous ghrelin. The fluorescently-labeled ghrelin analog is a valuable tool for in vitro imaging of cell lines that express ghrelin receptor.
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Affiliation(s)
- Mengjie Liu
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Emily A Whitfield
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Linda J Fothergill
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - John B Furness
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - John D Wade
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia; School of Chemistry, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - Mohammed Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia; School of Chemistry, The University of Melbourne, Parkville, VIC, 3010, Australia.
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Zhang X, Belousoff MJ, Zhao P, Kooistra AJ, Truong TT, Ang SY, Underwood CR, Egebjerg T, Šenel P, Stewart GD, Liang YL, Glukhova A, Venugopal H, Christopoulos A, Furness SGB, Miller LJ, Reedtz-Runge S, Langmead CJ, Gloriam DE, Danev R, Sexton PM, Wootten D. Differential GLP-1R Binding and Activation by Peptide and Non-peptide Agonists. Mol Cell 2020; 80:485-500.e7. [PMID: 33027691 DOI: 10.1016/j.molcel.2020.09.020] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 09/04/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022]
Abstract
Peptide drugs targeting class B1 G-protein-coupled receptors (GPCRs) can treat multiple diseases; however, there remains substantial interest in the development of orally delivered non-peptide drugs. Here, we reveal unexpected overlap between signaling and regulation of the glucagon-like peptide-1 (GLP-1) receptor by the non-peptide agonist PF 06882961 and GLP-1 that was not observed for another compound, CHU-128. Compounds from these patent series, including PF 06882961, are currently in clinical trials for treatment of type 2 diabetes. High-resolution cryoelectron microscopy (cryo-EM) structures reveal that the binding sites for PF 06882961 and GLP-1 substantially overlap, whereas CHU-128 adopts a unique binding mode with a more open receptor conformation at the extracellular face. Structural differences involving extensive water-mediated hydrogen bond networks could be correlated to functional data to understand how PF 06882961, but not CHU-128, can closely mimic the pharmacological properties of GLP-1. These findings will facilitate rational structure-based discovery of non-peptide agonists targeting class B GPCRs.
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Affiliation(s)
- Xin Zhang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Matthew J Belousoff
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Albert J Kooistra
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Tin T Truong
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Sheng Yu Ang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | | | | | - Petr Šenel
- Apigenex, Poděbradská 173/5, Prague 9 190 00, Czech Republic
| | - Gregory D Stewart
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Yi-Lynn Liang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Alisa Glukhova
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Hari Venugopal
- Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC 3168, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | | | - Christopher J Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - David E Gloriam
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, N415, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan.
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.
| | - Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.
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Dong M, Deganutti G, Piper SJ, Liang YL, Khoshouei M, Belousoff MJ, Harikumar KG, Reynolds CA, Glukhova A, Furness SGB, Christopoulos A, Danev R, Wootten D, Sexton PM, Miller LJ. Structure and dynamics of the active Gs-coupled human secretin receptor. Nat Commun 2020; 11:4137. [PMID: 32811827 PMCID: PMC7435274 DOI: 10.1038/s41467-020-17791-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 07/15/2020] [Indexed: 01/08/2023] Open
Abstract
The class B secretin GPCR (SecR) has broad physiological effects, with target potential for treatment of metabolic and cardiovascular disease. Molecular understanding of SecR binding and activation is important for its therapeutic exploitation. We combined cryo-electron microscopy, molecular dynamics, and biochemical cross-linking to determine a 2.3 Å structure, and interrogate dynamics, of secretin bound to the SecR:Gs complex. SecR exhibited a unique organization of its extracellular domain (ECD) relative to its 7-transmembrane (TM) core, forming more extended interactions than other family members. Numerous polar interactions formed between secretin and the receptor extracellular loops (ECLs) and TM helices. Cysteine-cross-linking, cryo-electron microscopy multivariate analysis and molecular dynamics simulations revealed that interactions between peptide and receptor were dynamic, and suggested a model for initial peptide engagement where early interactions between the far N-terminus of the peptide and SecR ECL2 likely occur following initial binding of the peptide C-terminus to the ECD.
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Affiliation(s)
- Maoqing Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
| | - Giuseppe Deganutti
- School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.,Centre for Sport, Exercise and Life Sciences, Faculty of Health and Life Sciences, Alison Gingell Building, Coventry University, CV1 2DS, Coventry, UK
| | - Sarah J Piper
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Yi-Lynn Liang
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Maryam Khoshouei
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.,Novartis Institutes for Biomedical Research, Novartis Pharma AG, 4002, Basel, Switzerland
| | - Matthew J Belousoff
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Kaleeckal G Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
| | | | - Alisa Glukhova
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, N415, 7-3-1 Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - Patrick M Sexton
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA.
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10
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Liang YL, Belousoff MJ, Fletcher MM, Zhang X, Khoshouei M, Deganutti G, Koole C, Furness SGB, Miller LJ, Hay DL, Christopoulos A, Reynolds CA, Danev R, Wootten D, Sexton PM. Structure and Dynamics of Adrenomedullin Receptors AM 1 and AM 2 Reveal Key Mechanisms in the Control of Receptor Phenotype by Receptor Activity-Modifying Proteins. ACS Pharmacol Transl Sci 2020; 3:263-284. [PMID: 32296767 PMCID: PMC7155201 DOI: 10.1021/acsptsci.9b00080] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 12/14/2022]
Abstract
Adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) receptors are critically important for metabolism, vascular tone, and inflammatory response. AM receptors are also required for normal lymphatic and blood vascular development and angiogenesis. They play a pivotal role in embryo implantation and fertility and can provide protection against hypoxic and oxidative stress. CGRP and AM receptors are heterodimers of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1) (CGRPR), as well as RAMP2 or RAMP3 (AM1R and AM2R, respectively). However, the mechanistic basis for RAMP modulation of CLR phenotype is unclear. In this study, we report the cryo-EM structure of the AM1R in complex with AM and Gs at a global resolution of 3.0 Å, and structures of the AM2R in complex with either AM or intermedin/adrenomedullin 2 (AM2) and Gs at 2.4 and 2.3 Å, respectively. The structures reveal distinctions in the primary orientation of the extracellular domains (ECDs) relative to the receptor core and distinct positioning of extracellular loop 3 (ECL3) that are receptor-dependent. Analysis of dynamic data present in the cryo-EM micrographs revealed additional distinctions in the extent of mobility of the ECDs. Chimeric exchange of the linker region of the RAMPs connecting the TM helix and the ECD supports a role for this segment in controlling receptor phenotype. Moreover, a subset of the motions of the ECD appeared coordinated with motions of the G protein relative to the receptor core, suggesting that receptor ECD dynamics could influence G protein interactions. This work provides fundamental advances in our understanding of GPCR function and how this can be allosterically modulated by accessory proteins.
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Affiliation(s)
- Yi-Lynn Liang
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Matthew J. Belousoff
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Madeleine M. Fletcher
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Xin Zhang
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Maryam Khoshouei
- Department
of Molecular Structural Biology, Max Planck
Institute of Biochemistry, 82152 Martinsried, Germany
| | - Giuseppe Deganutti
- School
of Biological Sciences, University of Essex, Colchester CO4 3SQ, United Kingdom
| | - Cassandra Koole
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Sebastian G. B. Furness
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Laurence J. Miller
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
- Department
of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259, United States
| | - Debbie L. Hay
- School
of Biological Sciences, and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1142, New Zealand
| | - Arthur Christopoulos
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | | | - Radostin Danev
- Graduate
School of Medicine, University of Tokyo, S402, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Denise Wootten
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
- School
of Pharmacy, Fudan University, Shanghai 201203, China
| | - Patrick M. Sexton
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
- School
of Pharmacy, Fudan University, Shanghai 201203, China
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11
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Abstract
G protein-coupled receptors (GPCRs) participate in many pathophysiological processes as well as almost all aspects of normal physiology. They are present at the surface of all cell types making them amenable and attractive targets for pharmaceutical therapeutics. GPCRs possess complex pharmacology with the ability to be turned on to various extents, have their constitutive activity suppressed and even switch between signaling pathways to which they couple. Underlying this complex pharmacology is GPCR signaling efficacy, and differences in efficacy promoted by alternative ligands and in different tissues is of great interest to biology in general and also the pharmaceutical industry. In this review we hope to discuss what the molecular foundations of efficacy are and whether a new approach utilizing a rate-dependent model may provide new insights into this phenomenon.
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Affiliation(s)
- Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
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12
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Nguyen HTH, Wood RJ, Prawdiuk AR, Furness SGB, Xiao J, Murray SS, Fletcher JL. TrkB Agonist LM22A-4 Increases Oligodendroglial Populations During Myelin Repair in the Corpus Callosum. Front Mol Neurosci 2019; 12:205. [PMID: 31507374 PMCID: PMC6718610 DOI: 10.3389/fnmol.2019.00205] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 08/06/2019] [Indexed: 01/08/2023] Open
Abstract
The neurotrophin, brain-derived neurotrophic factor (BDNF) promotes central nervous system (CNS) myelination during development and after injury. This is achieved via activation of oligodendrocyte-expressed tropomyosin-related kinase (Trk) B receptors. However, while administration of BDNF has shown beneficial effects, BDNF itself has a poor pharmacokinetic profile. Here, we compare two TrkB-targeted BDNF-mimetics, the structural-mimetic, tricyclic dimeric peptide-6 (TDP6) and the non-peptide small molecule TrkB agonist LM22A-4 in a cuprizone model of central demyelination in female mice. Both mimetics promoted remyelination, increasing myelin sheath thickness and oligodendrocyte densities after 1-week recovery. Importantly, LM22A-4 exerts these effects in an oligodendroglial TrkB-dependent manner. However, analysis of TrkB signaling by LM22A-4 suggests rather than direct activation of TrkB, LM22A-4 exerts its effects via indirect transactivation of Trk receptors. Overall, these studies support the therapeutic strategy to selectively targeting TrkB activation to promote remyelination in the brain.
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Affiliation(s)
- Huynh T H Nguyen
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Rhiannon J Wood
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Alexa R Prawdiuk
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology, Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Junhua Xiao
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Simon S Murray
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Jessica L Fletcher
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
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13
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Pham V, Zhu Y, Dal Maso E, Reynolds CA, Deganutti G, Atanasio S, Hick CA, Yang D, Christopoulos A, Hay DL, Furness SGB, Wang MW, Wootten D, Sexton PM. Deconvoluting the Molecular Control of Binding and Signaling at the Amylin 3 Receptor: RAMP3 Alters Signal Propagation through Extracellular Loops of the Calcitonin Receptor. ACS Pharmacol Transl Sci 2019; 2:183-197. [PMID: 32219220 PMCID: PMC7088965 DOI: 10.1021/acsptsci.9b00010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Indexed: 12/18/2022]
Abstract
Amylin is coexpressed with insulin in pancreatic islet β-cells and has potent effects on gastric emptying and food intake. The effect of amylin on satiation has been postulated to involve AMY3 receptors (AMY3R) that are heteromers of the calcitonin receptor (CTR) and receptor activity-modifying protein 3 (RAMP3). Understanding the molecular control of signaling through the AMY3R is thus important for peptide drug targeting of this receptor. We have previously used alanine scanning mutagenesis to study the contribution of the extracellular surface of the CTR to binding and signaling initiated by calcitonin (CT) and related peptides (Dal Maso, E., et al. (2019) The molecular control of calcitonin receptor signaling. ACS Pharmacol. Transl. Sci. 2, 31-51). That work revealed ligand- and pathway-specific effects of mutation, with extracellular loops (ECLs) 2 and 3 particularly important in the distinct propagation of signaling mediated by individual peptides. In the current study, we have used equivalent alanine scanning of ECL2 and ECL3 of the CTR in the context of coexpression with RAMP3 to form AMY3Rs, to examine functional affinity and efficacy of peptides in cAMP accumulation and extracellular signal-regulated kinase (ERK) phosphorylation (pERK). The effect of mutation was determined on representatives of the three major distinct classes of CT peptide, salmon CT (sCT), human CT (hCT), and porcine CT (pCT), as well as rat amylin (rAmy) or human α-CGRP (calcitonin gene-related peptide, hCGRP) whose potency is enhanced by RAMP interaction. We demonstrate that the dynamic nature of CTR ECL2 and ECL3 in propagation of signaling is fundamentally altered when complexed with RAMP3 to form the AMY3R, despite only having predicted direct interactions with ECL2. Moreover, the work shows that the role of these loops in receptor signaling is highly peptide dependent, illustrating that even subtle changes to peptide sequence may change signaling output downstream of the receptor.
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Affiliation(s)
- Vi Pham
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Yue Zhu
- The
National Center for Drug Screening and CAS Key Laboratory of Receptor
Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
- University
of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Emma Dal Maso
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | | | - Giuseppe Deganutti
- School
of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K.
| | - Silvia Atanasio
- School
of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K.
| | - Caroline A. Hick
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Dehua Yang
- The
National Center for Drug Screening and CAS Key Laboratory of Receptor
Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Arthur Christopoulos
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Debbie L. Hay
- The
University of Auckland, School of Biological
Sciences, 3 Symonds Street, Auckland 1142, New Zealand
| | - Sebastian G. B. Furness
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Ming-Wei Wang
- The
National Center for Drug Screening and CAS Key Laboratory of Receptor
Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
- University
of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Denise Wootten
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Patrick M. Sexton
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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14
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Ostrovskaya A, Hick C, Hutchinson DS, Stringer BW, Wookey PJ, Wootten D, Sexton PM, Furness SGB. Expression and activity of the calcitonin receptor family in a sample of primary human high-grade gliomas. BMC Cancer 2019; 19:157. [PMID: 30777055 PMCID: PMC6379965 DOI: 10.1186/s12885-019-5369-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 02/11/2019] [Indexed: 12/16/2022] Open
Abstract
Background Glioblastoma (GBM) is the most common and aggressive type of primary brain cancer. With median survival of less than 15 months, identification and validation of new GBM therapeutic targets is of critical importance. Results In this study we tested expression and performed pharmacological characterization of the calcitonin receptor (CTR) as well as other members of the calcitonin family of receptors in high-grade glioma (HGG) cell lines derived from individual patient tumours, cultured in defined conditions. Previous immunohistochemical data demonstrated CTR expression in GBM biopsies and we were able to confirm CALCR (gene encoding CTR) expression. However, as assessed by cAMP accumulation assay, only one of the studied cell lines expressed functional CTR, while the other cell lines have functional CGRP (CLR/RAMP1) receptors. The only CTR-expressing cell line (SB2b) showed modest coupling to the cAMP pathway and no activation of other known CTR signaling pathways, including ERK1/2 and p38 MAP kinases, and Ca2+ mobilization, supportive of low cell surface receptor expression. Exome sequencing data failed to account for the discrepancy between functional data and expression on the cell lines that do not respond to calcitonin(s) with no deleterious non-synonymous polymorphisms detected, suggesting that other factors may be at play, such as alternative splicing or rapid constitutive receptor internalisation. Conclusions This study shows that GPCR signaling can display significant variation depending on cellular system used, and effects seen in model recombinant cell lines or tumour cell lines are not always reproduced in a more physiologically relevant system and vice versa. Electronic supplementary material The online version of this article (10.1186/s12885-019-5369-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anna Ostrovskaya
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Caroline Hick
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Dana S Hutchinson
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Brett W Stringer
- QIMR-Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Peter J Wookey
- Department of Medicine/Cardiology (Austin Health, Heidelberg), University of Melbourne, Lance Townsend Building, Level 10, Austin Campus, Studley Road, Heidelberg, VIC, 3084, Australia
| | - Denise Wootten
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.,School of Pharmacy, Fudan University, Shanghai, 201203, China
| | - Patrick M Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.,School of Pharmacy, Fudan University, Shanghai, 201203, China
| | - Sebastian G B Furness
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
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15
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dal Maso E, Glukhova A, Zhu Y, Garcia-Nafria J, Tate CG, Atanasio S, Reynolds CA, Ramírez-Aportela E, Carazo JM, Hick CA, Furness SGB, Hay DL, Liang YL, Miller LJ, Christopoulos A, Wang MW, Wootten D, Sexton PM. The Molecular Control of Calcitonin Receptor Signaling. ACS Pharmacol Transl Sci 2019; 2:31-51. [PMID: 32219215 PMCID: PMC7088896 DOI: 10.1021/acsptsci.8b00056] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Indexed: 12/12/2022]
Abstract
The calcitonin receptor (CTR) is a class B G protein-coupled receptor (GPCR) that responds to the peptide hormone calcitonin (CT). CTs are clinically approved for the treatment of bone diseases. We previously reported a 4.1 Å structure of the activated CTR bound to salmon CT (sCT) and heterotrimeric Gs protein by cryo-electron microscopy (Liang, Y.-L., et al. Phase-plate cryo- EM structure of a class B GPCR-G protein complex. Nature 2017, 546, 118-123). In the current study, we have reprocessed the electron micrographs to yield a 3.3 Å map of the complex. This has allowed us to model extracellular loops (ECLs) 2 and 3, and the peptide N-terminus that previously could not be resolved. We have also performed alanine scanning mutagenesis of ECL1 and the upper segment of transmembrane helix 1 (TM1) and its extension into the receptor extracellular domain (TM1 stalk), with effects on peptide binding and function assessed by cAMP accumulation and ERK1/2 phosphorylation. These data were combined with previously published alanine scanning mutagenesis of ECL2 and ECL3 and the new structural information to provide a comprehensive 3D map of the molecular surface of the CTR that controls binding and signaling of distinct CT and related peptides. The work highlights distinctions in how different, related, class B receptors may be activated. The new mutational data on the TM1 stalk and ECL1 have also provided critical insights into the divergent control of cAMP versus pERK signaling and, collectively with previous mutagenesis data, offer evidence that the conformations linked to these different signaling pathways are, in many ways, mutually exclusive. This study furthers our understanding of the complex nature of signaling elicited by GPCRs and, in particular, that of the therapeutically important class B subfamily.
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Affiliation(s)
- Emma dal Maso
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
| | - Alisa Glukhova
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
| | - Yue Zhu
- The
National Center for Drug Screening and CAS Key Laboratory of Receptor
Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
- University
of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Javier Garcia-Nafria
- MRC
Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, U.K.
| | - Christopher G. Tate
- MRC
Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, U.K.
| | - Silvia Atanasio
- School
of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K.
| | | | - Erney Ramírez-Aportela
- Biocomputing
Unit, National Center for Biotechnology
(CNB-CSIC), C/Darwin,
3, Campus Universidad Autónoma, 28049 Cantoblanco, Madrid Spain
| | - Jose-Maria Carazo
- Biocomputing
Unit, National Center for Biotechnology
(CNB-CSIC), C/Darwin,
3, Campus Universidad Autónoma, 28049 Cantoblanco, Madrid Spain
| | - Caroline A. Hick
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
| | - Sebastian G. B. Furness
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
| | - Debbie L. Hay
- The
University of Auckland, School of Biological
Sciences, 3 Symonds Street, Auckland 1142, New Zealand
| | - Yi-Lynn Liang
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
| | - Laurence J. Miller
- Department
of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259, United States
| | - Arthur Christopoulos
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
| | - Ming-Wei Wang
- The
National Center for Drug Screening and CAS Key Laboratory of Receptor
Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
- University
of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
- School
of Pharmacy, Fudan University, Shanghai 201203, China
| | - Denise Wootten
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
- School
of Pharmacy, Fudan University, Shanghai 201203, China
| | - Patrick M. Sexton
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria Australia
- School
of Pharmacy, Fudan University, Shanghai 201203, China
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16
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Liang YL, Zhao P, Draper-Joyce C, Baltos JA, Glukhova A, Truong TT, May LT, Christopoulos A, Wootten D, Sexton PM, Furness SGB. Dominant Negative G Proteins Enhance Formation and Purification of Agonist-GPCR-G Protein Complexes for Structure Determination. ACS Pharmacol Transl Sci 2018; 1:12-20. [PMID: 32219201 DOI: 10.1021/acsptsci.8b00017] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Indexed: 12/18/2022]
Abstract
Advances in structural biology have yielded exponential growth in G protein-coupled receptor (GPCR) structure solution. Nonetheless, the instability of fully active GPCR complexes with cognate heterotrimeric G proteins has made them elusive. Existing structures have been limited to nanobody-stabilized GPCR:Gs complexes. Here we present methods for enhanced GPCR:G protein complex stabilization via engineering G proteins with reduced nucleotide affinity, limiting Gα:Gβγ dissociation. We illustrate the application of dominant negative G proteins of Gαs and Gαi2 to the purification of stable complexes where this was not possible with wild-type G protein. Active state complexes of adenosine:A1 receptor:Gαi2βγ and calcitonin gene-related peptide (CGRP):CLR:RAMP1:Gαsβγ:Nb35 were purified to homogeneity and were stable in negative stain electron microscopy. These were suitable for structure determination by cryo-electron microscopy at 3.6 and 3.3 Å resolution, respectively. The dominant negative Gα-proteins are thus high value tools for structure determination of agonist:GPCR:G protein complexes that are critical for informed translational drug discovery.
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Affiliation(s)
- Yi-Lynn Liang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Christopher Draper-Joyce
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Jo-Anne Baltos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Alisa Glukhova
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Tin T Truong
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
| | - Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia.,School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia.,School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Australia
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17
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Liang YL, Khoshouei M, Glukhova A, Furness SGB, Zhao P, Clydesdale L, Koole C, Truong TT, Thal DM, Lei S, Radjainia M, Danev R, Baumeister W, Wang MW, Miller LJ, Christopoulos A, Sexton PM, Wootten D. Phase-plate cryo-EM structure of a biased agonist-bound human GLP-1 receptor-Gs complex. Nature 2018; 555:121-125. [PMID: 29466332 DOI: 10.1038/nature25773] [Citation(s) in RCA: 206] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 01/17/2018] [Indexed: 12/20/2022]
Abstract
The class B glucagon-like peptide-1 (GLP-1) G protein-coupled receptor is a major target for the treatment of type 2 diabetes and obesity. Endogenous and mimetic GLP-1 peptides exhibit biased agonism-a difference in functional selectivity-that may provide improved therapeutic outcomes. Here we describe the structure of the human GLP-1 receptor in complex with the G protein-biased peptide exendin-P5 and a Gαs heterotrimer, determined at a global resolution of 3.3 Å. At the extracellular surface, the organization of extracellular loop 3 and proximal transmembrane segments differs between our exendin-P5-bound structure and previous GLP-1-bound GLP-1 receptor structure. At the intracellular face, there was a six-degree difference in the angle of the Gαs-α5 helix engagement between structures, which was propagated across the G protein heterotrimer. In addition, the structures differed in the rate and extent of conformational reorganization of the Gαs protein. Our structure provides insights into the molecular basis of biased agonism.
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Affiliation(s)
- Yi-Lynn Liang
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Maryam Khoshouei
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Alisa Glukhova
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Peishen Zhao
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Lachlan Clydesdale
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Cassandra Koole
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Tin T Truong
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - David M Thal
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Saifei Lei
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.,The National Center for Drug Screening and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Mazdak Radjainia
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,FEI, 5651 GG Eindhoven, The Netherlands
| | - Radostin Danev
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Ming-Wei Wang
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.,The National Center for Drug Screening and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Laurence J Miller
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259, USA
| | - Arthur Christopoulos
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Denise Wootten
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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18
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Gilabert-Oriol R, Furness SGB, Stringer BW, Weng A, Fuchs H, Day BW, Kourakis A, Boyd AW, Hare DL, Thakur M, Johns TG, Wookey PJ. Dianthin-30 or gelonin versus monomethyl auristatin E, each configured with an anti-calcitonin receptor antibody, are differentially potent in vitro in high-grade glioma cell lines derived from glioblastoma. Cancer Immunol Immunother 2017; 66:1217-1228. [PMID: 28501939 PMCID: PMC11029669 DOI: 10.1007/s00262-017-2013-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 05/06/2017] [Indexed: 11/27/2022]
Abstract
We have reported that calcitonin receptor (CTR) is widely expressed in biopsies from the lethal brain tumour glioblastoma by malignant glioma and brain tumour-initiating cells (glioma stem cells) using anti-human CTR antibodies. A monoclonal antibody against an epitope within the extracellular domain of CTR was raised (mAb2C4) and chemically conjugated to either plant ribosome-inactivating proteins (RIPs) dianthin-30 or gelonin, or the drug monomethyl auristatin E (MMAE), and purified. In the high-grade glioma cell line (HGG, representing glioma stem cells) SB2b, in the presence of the triterpene glycoside SO1861, the EC50 for mAb2C4:dianthin was 10.0 pM and for mAb2C4:MMAE [antibody drug conjugate (ADC)] 2.5 nM, 250-fold less potent. With the cell line U87MG, in the presence of SO1861, the EC50 for mAb2C4:dianthin was 20 pM, mAb2C4:gelonin, 20 pM, compared to the ADC (6.3 nM), which is >300 less potent. Several other HGG cell lines that express CTR were tested and the efficacies of mAb2C4:RIP (dianthin or gelonin) were similar. Co-administration of the enhancer SO1861 purified from plants enhances lysosomal escape. Enhancement with SO1861 increased potency of the immunotoxin (>3 log values) compared to the ADC (1 log). The uptake of antibody was demonstrated with the fluorescent conjugate mAb2C4:Alexa Fluor 568, and the release of dianthin-30:Alexa Fluor488 into the cytosol following addition of SO1861 supports our model. These data demonstrate that the immunotoxins are highly potent and that CTR is an effective target expressed by a large proportion of HGG cell lines representative of glioma stem cells and isolated from individual patients.
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Affiliation(s)
- Roger Gilabert-Oriol
- Department of Medicine/Cardiology (Austin Health, Heidelberg), University of Melbourne, Lance Townsend Building, Level 10, Austin Campus, Studley Road, Heidelberg, VIC, 3084, Australia
- Department of Experimental Therapeutics, BC Cancer Research Centre, 675 W 10th Ave, Vancouver, BC, V5Z IL3, Canada
| | - Sebastian G B Furness
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University (Parkville), Parkville, VIC, Australia
| | - Brett W Stringer
- QIMR-Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Alexander Weng
- Institut für Laboratoriumsmedizin, Klinische Chemie und Pathobiochemie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353, Berlin, Germany
- Institute of Pharmacy, Königin-Luise-Str. 2+4, 14195, Berlin, Germany
| | - Hendrik Fuchs
- Institut für Laboratoriumsmedizin, Klinische Chemie und Pathobiochemie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Bryan W Day
- QIMR-Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Angela Kourakis
- Department of Medicine/Cardiology (Austin Health, Heidelberg), University of Melbourne, Lance Townsend Building, Level 10, Austin Campus, Studley Road, Heidelberg, VIC, 3084, Australia
| | - Andrew W Boyd
- QIMR-Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - David L Hare
- Department of Medicine/Cardiology (Austin Health, Heidelberg), University of Melbourne, Lance Townsend Building, Level 10, Austin Campus, Studley Road, Heidelberg, VIC, 3084, Australia
| | - Mayank Thakur
- Institut für Laboratoriumsmedizin, Klinische Chemie und Pathobiochemie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Terrance G Johns
- Hudson Institute of Medical Research, Monash University (Clayton), Clayton, VIC, Australia
| | - Peter J Wookey
- Department of Medicine/Cardiology (Austin Health, Heidelberg), University of Melbourne, Lance Townsend Building, Level 10, Austin Campus, Studley Road, Heidelberg, VIC, 3084, Australia.
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19
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Liang YL, Khoshouei M, Radjainia M, Zhang Y, Glukhova A, Tarrasch J, Thal DM, Furness SGB, Christopoulos G, Coudrat T, Danev R, Baumeister W, Miller LJ, Christopoulos A, Kobilka BK, Wootten D, Skiniotis G, Sexton PM. Phase-plate cryo-EM structure of a class B GPCR-G-protein complex. Nature 2017; 546:118-123. [PMID: 28437792 PMCID: PMC5832441 DOI: 10.1038/nature22327] [Citation(s) in RCA: 346] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/03/2017] [Indexed: 12/19/2022]
Abstract
Class B G-protein-coupled receptors are major targets for the treatment of chronic diseases, such as osteoporosis, diabetes and obesity. Here we report the structure of a full-length class B receptor, the calcitonin receptor, in complex with peptide ligand and heterotrimeric Gαsβγ protein determined by Volta phase-plate single-particle cryo-electron microscopy. The peptide agonist engages the receptor by binding to an extended hydrophobic pocket facilitated by the large outward movement of the extracellular ends of transmembrane helices 6 and 7. This conformation is accompanied by a 60° kink in helix 6 and a large outward movement of the intracellular end of this helix, opening the bundle to accommodate interactions with the α5-helix of Gαs. Also observed is an extended intracellular helix 8 that contributes to both receptor stability and functional G-protein coupling via an interaction with the Gβ subunit. This structure provides a new framework for understanding G-protein-coupled receptor function.
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Affiliation(s)
- Yi-Lynn Liang
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Maryam Khoshouei
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Mazdak Radjainia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Victoria, Australia
| | - Yan Zhang
- Life Sciences Institute and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-2216, U.S.A
| | - Alisa Glukhova
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Jeffrey Tarrasch
- Life Sciences Institute and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-2216, U.S.A
| | - David M Thal
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Sebastian G. B. Furness
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - George Christopoulos
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Thomas Coudrat
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Radostin Danev
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Laurence J. Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259, U.S.A
| | - Arthur Christopoulos
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Denise Wootten
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Georgios Skiniotis
- Life Sciences Institute and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-2216, U.S.A
| | - Patrick M. Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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20
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Furness SGB, Wootten D, Sexton PM. What determines the magnitude of cellular response for activation of G protein-coupled receptors? Cell Cycle 2017; 16:392-394. [PMID: 28055294 DOI: 10.1080/15384101.2016.1271634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Sebastian G B Furness
- a Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology , Monash University , Parkville , 3052 VIC , Australia
| | - Denise Wootten
- a Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology , Monash University , Parkville , 3052 VIC , Australia
| | - Patrick M Sexton
- a Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology , Monash University , Parkville , 3052 VIC , Australia
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21
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Wootten D, Reynolds CA, Smith KJ, Mobarec JC, Koole C, Savage EE, Pabreja K, Simms J, Sridhar R, Furness SGB, Liu M, Thompson PE, Miller LJ, Christopoulos A, Sexton PM. The Extracellular Surface of the GLP-1 Receptor Is a Molecular Trigger for Biased Agonism. Cell 2017; 165:1632-1643. [PMID: 27315480 PMCID: PMC4912689 DOI: 10.1016/j.cell.2016.05.023] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/16/2016] [Accepted: 05/03/2016] [Indexed: 12/25/2022]
Abstract
Ligand-directed signal bias offers opportunities for sculpting molecular events, with the promise of better, safer therapeutics. Critical to the exploitation of signal bias is an understanding of the molecular events coupling ligand binding to intracellular signaling. Activation of class B G protein-coupled receptors is driven by interaction of the peptide N terminus with the receptor core. To understand how this drives signaling, we have used advanced analytical methods that enable separation of effects on pathway-specific signaling from those that modify agonist affinity and mapped the functional consequence of receptor modification onto three-dimensional models of a receptor-ligand complex. This yields molecular insights into the initiation of receptor activation and the mechanistic basis for biased agonism. Our data reveal that peptide agonists can engage different elements of the receptor extracellular face to achieve effector coupling and biased signaling providing a foundation for rational design of biased agonists. Effect of mutation on affinity and efficacy of biased ligands mapped onto 3D models Biased agonists form distinct interactions with the GLP-1R extracellular surface Engagement of unique elements of the extracellular surface promotes biased agonism Insights into class B GPCR activation/biased agonism can aid rational drug design
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Affiliation(s)
- Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
| | | | - Kevin J Smith
- School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Juan C Mobarec
- School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Cassandra Koole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia; Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Emilia E Savage
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Kavita Pabreja
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - John Simms
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
| | - Rohan Sridhar
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Mengjie Liu
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
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22
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Wootten D, Reynolds CA, Smith KJ, Mobarec JC, Furness SGB, Miller LJ, Christopoulos A, Sexton PM. Key interactions by conserved polar amino acids located at the transmembrane helical boundaries in Class B GPCRs modulate activation, effector specificity and biased signalling in the glucagon-like peptide-1 receptor. Biochem Pharmacol 2016; 118:68-87. [PMID: 27569426 PMCID: PMC5063953 DOI: 10.1016/j.bcp.2016.08.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/15/2016] [Indexed: 11/28/2022]
Abstract
Class B GPCRs can activate multiple signalling effectors with the potential to exhibit biased agonism in response to ligand stimulation. Previously, we highlighted key TM domain polar amino acids that were crucial for the function of the GLP-1 receptor, a key therapeutic target for diabetes and obesity. Using a combination of mutagenesis, pharmacological characterisation, mathematical and computational molecular modelling, this study identifies additional highly conserved polar residues located towards the TM helical boundaries of Class B GPCRs that are important for GLP-1 receptor stability and/or controlling signalling specificity and biased agonism. This includes (i) three positively charged residues (R3.30227, K4.64288, R5.40310) located at the extracellular boundaries of TMs 3, 4 and 5 that are predicted in molecular models to stabilise extracellular loop 2, a crucial domain for ligand affinity and receptor activation; (ii) a predicted hydrogen bond network between residues located in TMs 2 (R2.46176), 6 (R6.37348) and 7 (N7.61406 and E7.63408) at the cytoplasmic face of the receptor that is important for stabilising the inactive receptor and directing signalling specificity, (iii) residues at the bottom of TM 5 (R5.56326) and TM6 (K6.35346 and K6.40351) that are crucial for receptor activation and downstream signalling; (iv) residues predicted to be involved in stabilisation of TM4 (N2.52182 and Y3.52250) that also influence cell signalling. Collectively, this work expands our understanding of peptide-mediated signalling by the GLP-1 receptor.
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Affiliation(s)
- Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
| | - Christopher A Reynolds
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Kevin J Smith
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Juan C Mobarec
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
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23
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Wootten D, Reynolds CA, Koole C, Smith KJ, Mobarec JC, Simms J, Quon T, Coudrat T, Furness SGB, Miller LJ, Christopoulos A, Sexton PM. A Hydrogen-Bonded Polar Network in the Core of the Glucagon-Like Peptide-1 Receptor Is a Fulcrum for Biased Agonism: Lessons from Class B Crystal Structures. Mol Pharmacol 2015; 89:335-47. [PMID: 26700562 DOI: 10.1124/mol.115.101246] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 12/17/2015] [Indexed: 12/25/2022] Open
Abstract
The glucagon-like peptide 1 (GLP-1) receptor is a class B G protein-coupled receptor (GPCR) that is a key target for treatments for type II diabetes and obesity. This receptor, like other class B GPCRs, displays biased agonism, though the physiologic significance of this is yet to be elucidated. Previous work has implicated R2.60(190), N3.43(240), Q7.49(394), and H6.52(363) as key residues involved in peptide-mediated biased agonism, with R2.60(190), N3.43(240), and Q7.49(394) predicted to form a polar interaction network. In this study, we used novel insight gained from recent crystal structures of the transmembrane domains of the glucagon and corticotropin releasing factor 1 (CRF1) receptors to develop improved models of the GLP-1 receptor that predict additional key molecular interactions with these amino acids. We have introduced E6.53(364)A, N3.43(240)Q, Q7.49(394)N, and N3.43(240)Q/Q7.49(394)N mutations to probe the role of predicted H-bonding and charge-charge interactions in driving cAMP, calcium, or extracellular signal-regulated kinase (ERK) signaling. A polar interaction between E6.53(364) and R2.60(190) was predicted to be important for GLP-1- and exendin-4-, but not oxyntomodulin-mediated cAMP formation and also ERK1/2 phosphorylation. In contrast, Q7.49(394), but not R2.60(190)/E6.53(364) was critical for calcium mobilization for all three peptides. Mutation of N3.43(240) and Q7.49(394) had differential effects on individual peptides, providing evidence for molecular differences in activation transition. Collectively, this work expands our understanding of peptide-mediated signaling from the GLP-1 receptor and the key role that the central polar network plays in these events.
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Affiliation(s)
- Denise Wootten
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Christopher A Reynolds
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Cassandra Koole
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Kevin J Smith
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Juan C Mobarec
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - John Simms
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Tezz Quon
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Thomas Coudrat
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Sebastian G B Furness
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Laurence J Miller
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Arthur Christopoulos
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
| | - Patrick M Sexton
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (D.W., C.K., T.Q., T.C., S.G.B.F., A.C., P.M.S.); School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK (C.A.R., K.J.S., J.C.M.); School of Life and Health Sciences, Aston University, Birmingham, UK (J.S.); and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ (L.J.M.)
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Cook AE, Mistry SN, Gregory KJ, Furness SGB, Sexton PM, Scammells PJ, Conigrave AD, Christopoulos A, Leach K. Biased allosteric modulation at the CaS receptor engendered by structurally diverse calcimimetics. Br J Pharmacol 2015; 172:185-200. [PMID: 25220431 PMCID: PMC4280977 DOI: 10.1111/bph.12937] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 09/02/2014] [Accepted: 09/07/2014] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Clinical use of cinacalcet in hyperparathyroidism is complicated by its tendency to induce hypocalcaemia, arising partly from activation of calcium-sensing receptors (CaS receptors) in the thyroid and stimulation of calcitonin release. CaS receptor allosteric modulators that selectively bias signalling towards pathways that mediate desired effects [e.g. parathyroid hormone (PTH) suppression] rather than those mediating undesirable effects (e.g. elevated serum calcitonin), may offer better therapies. EXPERIMENTAL APPROACH We characterized the ligand-biased profile of novel calcimimetics in HEK293 cells stably expressing human CaS receptors, by monitoring intracellular calcium (Ca(2+) i ) mobilization, inositol phosphate (IP)1 accumulation, ERK1/2 phosphorylation (pERK1/2) and receptor expression. KEY RESULTS Phenylalkylamine calcimimetics were biased towards allosteric modulation of Ca(2+) i mobilization and IP1 accumulation. S,R-calcimimetic B was biased only towards IP1 accumulation. R,R-calcimimetic B and AC-265347 were biased towards IP1 accumulation and pERK1/2. Nor-calcimimetic B was unbiased. In contrast to phenylalkylamines and calcimimetic B analogues, AC-265347 did not promote trafficking of a loss-of-expression, naturally occurring, CaS receptor mutation (G(670) E). CONCLUSIONS AND IMPLICATIONS The ability of R,R-calcimimetic B and AC-265347 to bias signalling towards pERK1/2 and IP1 accumulation may explain their suppression of PTH levels in vivo at concentrations that have no effect on serum calcitonin levels. The demonstration that AC-265347 promotes CaS receptor receptor signalling, but not trafficking reveals a novel profile of ligand-biased modulation at CaS receptors The identification of allosteric modulators that bias CaS receptor signalling towards distinct intracellular pathways provides an opportunity to develop desirable biased signalling profiles in vivo for mediating selective physiological responses.
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Affiliation(s)
- A E Cook
- Drug Discovery Biology and Department of Pharmacology, Monash University, Parkville, Vic., Australia
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25
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Pabreja K, Mohd MA, Koole C, Wootten D, Furness SGB. Molecular mechanisms underlying physiological and receptor pleiotropic effects mediated by GLP-1R activation. Br J Pharmacol 2014; 171:1114-28. [PMID: 23889512 DOI: 10.1111/bph.12313] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/10/2013] [Accepted: 07/19/2013] [Indexed: 12/22/2022] Open
Abstract
The incidence of type 2 diabetes in developed countries is increasing yearly with a significant negative impact on patient quality of life and an enormous burden on the healthcare system. Current biguanide and thiazolidinedione treatments for type 2 diabetes have a number of clinical limitations, the most serious long-term limitation being the eventual need for insulin replacement therapy (Table 1). Since 2007, drugs targeting the glucagon-like peptide-1 (GLP-1) receptor have been marketed for the treatment of type 2 diabetes. These drugs have enjoyed a great deal of success even though our underlying understanding of the mechanisms for their pleiotropic effects remain poorly characterized even while major pharmaceutical companies actively pursue small molecule alternatives. Coupling of the GLP-1 receptor to more than one signalling pathway (pleiotropic signalling) can result in ligand-dependent signalling bias and for a peptide receptor such as the GLP-1 receptor this can be exaggerated with the use of small molecule agonists. Better consideration of receptor signalling pleiotropy will be necessary for future drug development. This is particularly important given the recent failure of taspoglutide, the report of increased risk of pancreatitis associated with GLP-1 mimetics and the observed clinical differences between liraglutide, exenatide and the newly developed long-acting exenatide long acting release, albiglutide and dulaglutide.
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Affiliation(s)
- K Pabreja
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
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26
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Hao N, Lee KL, Furness SGB, Bosdotter C, Poellinger L, Whitelaw ML. Xenobiotics and loss of cell adhesion drive distinct transcriptional outcomes by aryl hydrocarbon receptor signaling. Mol Pharmacol 2012; 82:1082-93. [PMID: 22936816 DOI: 10.1124/mol.112.078873] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a signal-regulated transcription factor, which is canonically activated by the direct binding of xenobiotics. In addition, switching cells from adherent to suspension culture also activates the AhR, representing a nonxenobiotic, physiological activation of AhR signaling. Here, we show that the AhR is recruited to target gene enhancers in both ligand [isopropyl-2-(1,3-dithietane-2-ylidene)-2-[N-(4-methylthiazol-2-yl)carbamoyl]acetate (YH439)]-treated and suspension cells, suggesting a common mechanism of target gene induction between these two routes of AhR activation. However, gene expression profiles critically differ between xenobiotic- and suspension-activated AhR signaling. Por and Cldnd1 were regulated predominantly by ligand treatments, whereas, in contrast, ApoER2 and Ganc were regulated predominantly by the suspension condition. Classic xenobiotic-metabolizing AhR targets such as Cyp1a1, Cyp1b1, and Nqo1 were regulated by both ligand and suspension conditions. Temporal expression patterns of AhR target genes were also found to vary, with examples of transient activation, transient repression, or sustained alterations in expression. Furthermore, sequence analysis coupled with chromatin immunoprecipitation assays and reporter gene analysis identified a functional xenobiotic response element (XRE) in the intron 1 of the mouse Tiparp gene, which was also bound by hypoxia-inducible factor-1α during hypoxia and features a concatemer of four XRE cores (GCGTG). Our data suggest that this XRE concatemer site concurrently regulates the expression of both the Tiparp gene and its cis antisense noncoding RNA after ligand- or suspension-induced AhR activation. This work provides novel insights into how AhR signaling drives different transcriptional programs via the ligand versus suspension modes of activation.
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Affiliation(s)
- Nan Hao
- School of Molecular and Biomedical Science (Biochemistry) and Australian Research Council Special Research Centre for the Molecular Genetics of Development, the University of Adelaide, Adelaide, South Australia, Australia
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27
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Willard FS, Wootten D, Showalter AD, Savage EE, Ficorilli J, Farb TB, Bokvist K, Alsina-Fernandez J, Furness SGB, Christopoulos A, Sexton PM, Sloop KW. Small molecule allosteric modulation of the glucagon-like Peptide-1 receptor enhances the insulinotropic effect of oxyntomodulin. Mol Pharmacol 2012; 82:1066-73. [PMID: 22930710 DOI: 10.1124/mol.112.080432] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Identifying novel mechanisms to enhance glucagon-like peptide-1 (GLP-1) receptor signaling may enable nascent medicinal chemistry strategies with the aim of developing new orally available therapeutic agents for the treatment of type 2 diabetes mellitus. Therefore, we tested the hypothesis that selectively modulating the low-affinity GLP-1 receptor agonist, oxyntomodulin, would improve the insulin secretory properties of this naturally occurring hormone to provide a rationale for pursuing an unexplored therapeutic approach. Signal transduction and competition binding studies were used to investigate oxyntomodulin activity on the GLP-1 receptor in the presence of the small molecule GLP-1 receptor modulator, 4-(3-benzyloxyphenyl)-2-ethylsulfinyl-6-(trifluoromethyl)pyrimidine (BETP). In vivo, the intravenous glucose tolerance test characterized oxyntomodulin-induced insulin secretion in animals administered the small molecule. BETP increased oxyntomodulin binding affinity for the GLP-1 receptor and enhanced oxyntomodulin-mediated GLP-1 receptor signaling as measured by activation of the α subunit of heterotrimeric G protein and cAMP accumulation. In addition, oxyntomodulin-induced insulin secretion was enhanced in the presence of the compound. BETP was pharmacologically characterized to induce biased signaling by oxyntomodulin. These studies demonstrate that small molecules targeting the GLP-1 receptor can increase binding and receptor activation of the endogenous peptide oxyntomodulin. The biased signaling engendered by BETP suggests that GLP-1 receptor mobilization of cAMP is the critical insulinotropic signaling event. Because of the unique metabolic properties of oxyntomodulin, identifying molecules that enhance its activity should be pursued to assess the efficacy and safety of this novel mechanism.
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Affiliation(s)
- Francis S Willard
- Translational Science and Technologies, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
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Furness SGB, Wootten D, Christopoulos A, Sexton PM. Consequences of splice variation on Secretin family G protein-coupled receptor function. Br J Pharmacol 2012; 166:98-109. [PMID: 21718310 DOI: 10.1111/j.1476-5381.2011.01571.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The Secretin family of GPCRs are endocrine peptide hormone receptors that share a common genomic organization and are the subject of a wide variety of alternative splicing. All GPCRs contain a central seven transmembrane domain responsible for transducing signals from the outside of the cell as well as extracellular amino and intracellular carboxyl termini. Members of the Secretin receptor family have a relatively large N-terminus and a variety of lines of evidence support a common mode of ligand binding and a common ligand binding fold. These receptors are best characterized as coupling to intracellular signalling pathways via G(αs) and G(αq) but are also reported to couple to a multitude of other signalling pathways. The intracellular loops are implicated in regulating the interaction between the receptor and heterotrimeric G protein complexes. Alternative splicing of exons encoding both the extracellular N-terminal domain as well as the extracellular loops of some family members has been reported and as expected these splice variants display altered ligand affinity as well as differential activation by endogenous ligands. Various forms of alternative splicing have also been reported to alter intracellular loops 1 and 3 as well as the C-terminus and as one might expect these display differences in signalling bias towards downstream effectors. These diverse pharmacologies require that the physiological role of these splice variants be addressed but should provide unique opportunities for drug design and development.
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Sato M, Hutchinson DS, Halls ML, Furness SGB, Bengtsson T, Evans BA, Summers RJ. Interaction with caveolin-1 modulates G protein coupling of mouse β3-adrenoceptor. J Biol Chem 2012; 287:20674-88. [PMID: 22535965 DOI: 10.1074/jbc.m111.280651] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Caveolins act as scaffold proteins in multiprotein complexes and have been implicated in signaling by G protein-coupled receptors. Studies using knock-out mice suggest that β(3)-adrenoceptor (β(3)-AR) signaling is dependent on caveolin-1; however, it is not known whether caveolin-1 is associated with the β(3)-AR or solely with downstream signaling proteins. We have addressed this question by examining the impact of membrane rafts and caveolin-1 on the differential signaling of mouse β(3a)- and β(3b)-AR isoforms that diverge at the distal C terminus. Only the β(3b)-AR promotes pertussis toxin (PTX)-sensitive cAMP accumulation. When cells expressing the β(3a)-AR were treated with filipin III to disrupt membrane rafts or transfected with caveolin-1 siRNA, the cyclic AMP response to the β(3)-AR agonist CL316243 became PTX-sensitive, suggesting Gα(i/o) coupling. The β(3a)-AR C terminus, SP(384)PLNRF(389)DGY(392)EGARPF(398)PT, resembles a caveolin interaction motif. Mutant β(3a)-ARs (F389A/Y392A/F398A or P384S/F389A) promoted PTX-sensitive cAMP responses, and in situ proximity assays demonstrated an association between caveolin-1 and the wild type β(3a)-AR but not the mutant receptors. In membrane preparations, the β(3b)-AR activated Gα(o) and mediated PTX-sensitive cAMP responses, whereas the β(3a)-AR did not activate Gα(i/o) proteins. The endogenous β(3a)-AR displayed Gα(i/o) coupling in brown adipocytes from caveolin-1 knock-out mice or in wild type adipocytes treated with filipin III. Our studies indicate that interaction of the β(3a)-AR with caveolin inhibits coupling to Gα(i/o) proteins and suggest that signaling is modulated by a raft-enriched complex containing the β(3a)-AR, caveolin-1, Gα(s), and adenylyl cyclase.
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Affiliation(s)
- Masaaki Sato
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and the Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
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30
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Wookey PJ, McLean CA, Hwang P, Furness SGB, Nguyen S, Kourakis A, Hare DL, Rosenfeld JV. The expression of calcitonin receptor detected in malignant cells of the brain tumour glioblastoma multiforme and functional properties in the cell line A172. Histopathology 2012; 60:895-910. [DOI: 10.1111/j.1365-2559.2011.04146.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Whelan F, Hao N, Furness SGB, Whitelaw ML, Chapman-Smith A. Amino acid substitutions in the aryl hydrocarbon receptor ligand binding domain reveal YH439 as an atypical AhR activator. Mol Pharmacol 2010; 77:1037-46. [PMID: 20231332 DOI: 10.1124/mol.109.062927] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is traditionally defined as a transcription factor activated by exogenous polyaromatic and halogenated aromatic hydrocarbon (PAH/HAH) ligands. Active AhR induces genes involved in xenobiotic metabolism, including cytochrome P4501A1, which function to metabolize activating ligands. However, recent studies implicate AhR in biological events that are apparently unrelated to the xenobiotic response, implying that endogenous activation mechanisms exist. Three AhR genes in zebrafish (Danio rerio) encode proteins that demonstrate differential activation in response to PAH/HAHs, with the nonresponsive drAhR1a having some sequence divergence from the PAH/HAH-responsive AhRs in the ligand binding domain (LBD). We used these differences to guide the mutagenesis of mouse AhR (mAhR), aiming to generate variants that functionally discriminate between activation mechanisms. We found substitution of histidine 285 in the LBD with tyrosine gave a receptor that could be activated by isopropyl-2-(1,3-dithietane-2-ylidene)-2-[N-(4-methylthiazol-2-yl)carbamoyl]acetate (YH439), a potential AhR ligand chemically distinct from classic PAH/HAH-type ligands, but prevented activation by both exogenous PAH/HAH ligands and the endogenous activation mimics of suspension culture and application of shear-stressed serum. The differential response of H285Y mAhR to YH439 suggests that this activator has a novel mode of interaction that tolerates tyrosine at position 285 in the LBD and is distinct from the binding mode of the well characterized PAH/HAH ligands. In support of this, the PAH-type antagonist 3',4'-dimethoxyflavone blocked mAhR activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin but not YH439. Furthermore, the strict correlation between response to exogenous PAH/HAH ligands and mimics of endogenous activation suggests that a PAH-type ligand may underpin endogenous mechanisms of activation.
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Affiliation(s)
- Fiona Whelan
- Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, North Tce, Adelaide, SA 5005, Australia
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Furness SGB, Whelan F. The pleiotropy of dioxin toxicity--xenobiotic misappropriation of the aryl hydrocarbon receptor's alternative physiological roles. Pharmacol Ther 2009; 124:336-53. [PMID: 19781569 DOI: 10.1016/j.pharmthera.2009.09.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
Abstract
The aryl hydrocarbon receptor is a signal regulated transcription factor that has best been characterised as regulating the xenobiotic response to a variety of planar aromatic hydrocarbons. There is compelling evidence that it mediates most, if not all, of the toxic effects of dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin). Dioxin exposure results in a wide variety of toxic outcomes including severe wasting syndrome, chloracne, thymic involution, severe immune suppression, reduced fertility, hepatotoxicity, teratogenicity, tumour promotion and death. The pleiotropy of toxic outcomes implies the disruption of a wide range of normal physiological functions. The aryl hydrocarbon receptor has developmentally restricted expression as well as developmental defects in gene-targeted mice. It has a wide range of target genes that do not fit into the classical xenobiotic metabolising gene battery and has recently been shown to interact with NF-kappa B and the estrogen receptor. There is also evidence for its activation in the absence of exogenous ligand, all of which point to various roles outside xenobiotic metabolism. Ligands so far identified display differential activation potential with respect to receptor activity. This article addresses activities of the aryl hydrocarbon receptor that are outside the xenobiotic response. Known physiological roles are discussed as well as how their disruption contributes to the pleiotropic toxicity of TCDD.
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Affiliation(s)
- Sebastian G B Furness
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
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Dave KA, Whelan F, Bindloss C, Furness SGB, Chapman-Smith A, Whitelaw ML, Gorman JJ. Sulfonation and phosphorylation of regions of the dioxin receptor susceptible to methionine modifications. Mol Cell Proteomics 2008; 8:706-19. [PMID: 19059900 DOI: 10.1074/mcp.m800459-mcp200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Tagged murine dioxin receptor was purified from mammalian cells, digested with trypsin, and analyzed by capillary HPLC-MALDI-TOF/TOF-MS and -MS/MS. Several chromatographically distinct semitryptic peptides matching two regions spanning residues Glu(409)-Arg(424) and Ser(547)-Arg(555) of the dioxin receptor were revealed by de novo sequencing. Methionine residues at 418 and 548 were detected in these peptides as either unmodified or modified by moieties of 16 (oxidation) or 57 amu (S-carboxamidomethylation) or in a form corresponding to degradative removal of 105 amu from the S-carboxamidomethylated methionine. MS/MS spectra revealed that the peptides containing modified methionine residues also existed in forms with a modification of +80 amu on serine residues 411, 415, and 547. The MS/MS spectra of these peptide ions also revealed diagnostic neutral loss fragment ions of 64, 98, and/or 80 amu, and in some instances combinations of these neutral losses were apparent. Taken together, these data indicated that serines 411 and 547 of the dioxin receptor were sulfonated and serine 415 was phosphorylated. Separate digests of the dioxin receptor were prepared in H(2)(16)O and H(2)(18)O, and enzymatic dephosphorylation was subsequently performed on the H(2)(16)O digest only. The digests were mixed in equal proportions and analyzed by capillary HPLC-MALDI-TOF/TOF-MS and -MS/MS. This strategy confirmed assignment of sulfonation as the cause of the +80-amu modifications on serines 411 and 547 and phosphorylation as the predominant cause of the +80-amu modification of serine 415. The relative quantitation of phosphorylation and sulfonation enabled by this differential phosphatase strategy also suggested the presence of sulfonation on a serine other than residue 411 within the sequence spanning Glu(409)-Arg(424). This represents the first description of post-translational sulfonation sites and identification of a new phosphorylation site of the latent dioxin receptor. Furthermore this is only the second report of serine sulfonation of eukaryotic proteins. Mutagenesis studies are underway to assess the functional consequences of these modifications.
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Affiliation(s)
- Keyur A Dave
- Protein Discovery Centre, Queensland Institute of Medical Research, P. O. Royal Brisbane Hospital, Herston, Queensland 4029, Australia
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Morfis M, Tilakaratne N, Furness SGB, Christopoulos G, Werry TD, Christopoulos A, Sexton PM. Receptor activity-modifying proteins differentially modulate the G protein-coupling efficiency of amylin receptors. Endocrinology 2008; 149:5423-31. [PMID: 18599553 DOI: 10.1210/en.2007-1735] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Receptor activity-modifying proteins (RAMPs) 1, 2, and 3 are prototypic G protein-coupled receptor accessory proteins that can alter not only receptor trafficking but also receptor phenotype. Specific RAMP interaction with the calcitonin receptor (CTR) generates novel and distinct receptors for the peptide amylin; however, the role of RAMPs in receptor signaling is not understood. The current study demonstrates that RAMP interaction with the CTRa in COS-7 or HEK-293 cells leads to selective modulation of signaling pathways activated by the receptor complex. There was a 20- to 30-fold induction in amylin potency at CTR/RAMP1 (AMY1) and CTR/RAMP3 (AMY3) receptors, compared with CTR alone, for formation of the second-messenger cAMP that parallels an increase in amylin binding affinity. In contrast, only 2- to 5-fold induction of amylin potency was seen for mobilization of intracellular Ca++ or activation of ERK1/2. In addition, in COS-7 cells, the increase in amylin potency for Ca++ mobilization was 2-fold greater for AMY3 receptors, compared with AMY1 receptors and this paralleled the relative capacity of overexpression of Galphaq proteins to augment induction of high affinity 125I-amylin binding. These data demonstrate that RAMP-complexed receptors have a different signaling profile to CTRs expressed in the absence of RAMPs, and this is likely due to direct effects of the RAMP on G protein-coupling efficiency.
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Affiliation(s)
- Maria Morfis
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, and Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
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Furness SGB, Lees MJ, Whitelaw ML. The dioxin (aryl hydrocarbon) receptor as a model for adaptive responses of bHLH/PAS transcription factors. FEBS Lett 2007; 581:3616-25. [PMID: 17459381 DOI: 10.1016/j.febslet.2007.04.011] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/03/2007] [Accepted: 04/04/2007] [Indexed: 11/19/2022]
Abstract
This review examines the common theme of adaptive responses of bHLH/PAS proteins, using the dioxin receptor as a prototype. The bHLH/PAS family of transcriptional regulators are a group of key developmental and environmental stress sensing proteins. They employ a variety of post-translational control mechanisms to regulate their transcriptional output. Amongst this family, the dioxin receptor is best known for its ability to elicit toxic responses to dioxin and dioxin like chemicals even though it mediates more benign adaptive responses to non-toxic xenobiotics. We discuss what is known about dioxin receptor physiology, both adaptive and inherent, along with its molecular regulation and put this into the context of the wider bHLH/PAS family. We also raise the issue of its toxic responses, in particular the idea that it is the dysregulation of its poorly characterised housekeeping functions that leads to these outcomes.
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Affiliation(s)
- Sebastian G B Furness
- Drug Discovery Laboratory, Department of Pharmacology, Building 13E, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
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Tan PC, Furness SGB, Merkens H, Lin S, McCoy ML, Roskelley CD, Kast J, McNagny KM. Na+/H+ exchanger regulatory factor-1 is a hematopoietic ligand for a subset of the CD34 family of stem cell surface proteins. Stem Cells 2006; 24:1150-61. [PMID: 16410385 DOI: 10.1634/stemcells.2005-0426] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CD34 and its relatives, podocalyxin and endoglycan, comprise a family of surface sialomucins expressed by hematopoietic stem/progenitor cells and vascular endothelia. Recent data suggest that they serve as either pro- or antiadhesion molecules depending on their cellular context and their post-translational modifications. In addition, their ability to function as blockers of adhesion may be further regulated by their subcellular localization in membrane microdomains via activation-dependent linkage with the actin cytoskeleton. To gain further insights into the function and regulation of CD34-type molecules, we sought to identify the intracellular ligands that govern their localization. Using both genetic and biochemical approaches, we have identified the Na(+)/H(+) exchanger regulatory factor-1 (NHERF-1) as a selective ligand for podocalyxin and endoglycan but not for the closely related CD34. Furthermore, we show that NHERF-1 is expressed by all c-kit(+) /lineage marker(-)/Sca-1(+) cells, which are known to express podocalyxin and have long-term repopulating abilities. Finally, we show that these proteins relocalize and colocalize in response to cytokine signaling. The results suggest that this cytosolic adaptor protein may be important for mobilization of CD34-type proteins in the plasma membrane and may thereby regulate their ability to block or enhance hematopoietic cell adhesion.
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Affiliation(s)
- Poh C Tan
- The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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