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Abstract
Ghrelin is a peptide hormone secreted primarily by the stomach that acts upon the growth hormone secretagogue receptor (GHSR1), a G protein-coupled receptor whose functions include growth hormone secretion, appetite regulation, energy expenditure, regulation of adiposity, and insulin release. Following the discovery that GHSR1a stimulates food intake, receptor antagonists were developed as potential therapies to regulate appetite. However, despite reductions in signalling, the desired effects on appetite were absent. Studies in the past 15 years have demonstrated GHSR1a can interact with other transmembrane proteins, either by direct binding (i.e. heteromerisation) or via signalling cross-talk. These interactions have various effects on GHSR1a signalling including preferential coupling to one pathway (i.e. biased signalling), coupling to a unique G protein (G protein switching), suppression of GHSR1a signalling, and enhancement of signalling by both receptors. While many of these interactions have been shown in cells overexpressing the proteins of interest and remain to be verified in tissues, substantial evidence exists showing that GHSR1a and the dopamine receptor D1 (DRD1) form heteromers, which promote synaptic plasticity and formation of hippocampal memory. Additionally, a reduction in GHSR1a-DRD1 complexes in favour of establishment of GHSR1a-Aβ complexes correlates with Alzheimer's disease, indicating that GHSR1a heteromers may have pathological functions. Herein, we summarise the evidence published to date describing interactions between GHSR1a and transmembrane proteins, discuss the experimental strengths and limitations of these studies, describe the physiological evidence for each interaction, and address their potential as novel drug targets for appetite regulation, Alzheimer's disease, insulin secretion, and inflammation.
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Affiliation(s)
- Maria L Price
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK
| | - Cameron D Ley
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK
| | - Caroline M Gorvin
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK
- Correspondence should be addressed to C M Gorvin:
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2
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Meijles DN, Fuller SJ, Cull JJ, Alharbi HO, Cooper STE, Sugden PH, Clerk A. The insulin receptor family and protein kinase B (Akt) are activated in the heart by alkaline pH and α1-adrenergic receptors. Biochem J 2021; 478:2059-79. [PMID: 34002209 DOI: 10.1042/BCJ20210144] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/10/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
Insulin and insulin-like growth factor stimulate protein synthesis and cardioprotection in the heart, acting through their receptors (INSRs, IGF1Rs) and signalling via protein kinase B (PKB, also known as Akt). Protein synthesis is increased in hearts perfused at alkaline pHo to the same extent as with insulin. Moreover, α1-adrenergic receptor (α1-AR) agonists (e.g. phenylephrine) increase protein synthesis in cardiomyocytes, activating PKB/Akt. In both cases, the mechanisms are not understood. Our aim was to determine if insulin receptor-related receptors (INSRRs, activated in kidney by alkaline pH) may account for the effects of alkaline pHo on cardiac protein synthesis, and establish if α1-ARs signal through the insulin receptor family. Alkaline pHo activated PKB/Akt signalling to the same degree as insulin in perfused adult male rat hearts. INSRRs were expressed in rat hearts and, by immunoblotting for phosphorylation (activation) of INSRRs/INSRs/IGF1Rs, we established that INSRRs, together with INSRs/IGF1Rs, are activated by alkaline pHo. The INSRR/INSR/IGF1R kinase inhibitor, linsitinib, prevented PKB/Akt activation by alkaline pHo, indicating that INSRRs/INSRs/IGF1Rs are required. Activation of PKB/Akt in cardiomyocytes by α1-AR agonists was also inhibited by linsitinib. Furthermore, linsitinib inhibited cardiomyocyte hypertrophy induced by α1-ARs in cultured cells, reduced the initial cardiac adaptation (24 h) to phenylephrine in vivo (assessed by echocardiography) and increased cardiac fibrosis over 4 days. We conclude that INSRRs are expressed in the heart and, together with INSRs/IGF1Rs, the insulin receptor family provide a potent system for promoting protein synthesis and cardioprotection. Moreover, this system is required for adaptive hypertrophy induced by α1-ARs.
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3
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Latko M, Czyrek A, Porębska N, Kucińska M, Otlewski J, Zakrzewska M, Opaliński Ł. Cross-Talk between Fibroblast Growth Factor Receptors and Other Cell Surface Proteins. Cells 2019; 8:E455. [PMID: 31091809 DOI: 10.3390/cells8050455] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 12/14/2022] Open
Abstract
Fibroblast growth factors (FGFs) and their receptors (FGFRs) constitute signaling circuits that transmit signals across the plasma membrane, regulating pivotal cellular processes like differentiation, migration, proliferation, and apoptosis. The malfunction of FGFs/FGFRs signaling axis is observed in numerous developmental and metabolic disorders, and in various tumors. The large diversity of FGFs/FGFRs functions is attributed to a great complexity in the regulation of FGFs/FGFRs-dependent signaling cascades. The function of FGFRs is modulated at several levels, including gene expression, alternative splicing, posttranslational modifications, and protein trafficking. One of the emerging ways to adjust FGFRs activity is through formation of complexes with other integral proteins of the cell membrane. These proteins may act as coreceptors, modulating binding of FGFs to FGFRs and defining specificity of elicited cellular response. FGFRs may interact with other cell surface receptors, like G-protein-coupled receptors (GPCRs) or receptor tyrosine kinases (RTKs). The cross-talk between various receptors modulates the strength and specificity of intracellular signaling and cell fate. At the cell surface FGFRs can assemble into large complexes involving various cell adhesion molecules (CAMs). The interplay between FGFRs and CAMs affects cell–cell interaction and motility and is especially important for development of the central nervous system. This review summarizes current stage of knowledge about the regulation of FGFRs by the plasma membrane-embedded partner proteins and highlights the importance of FGFRs-containing membrane complexes in pathological conditions, including cancer.
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4
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Abstract
The interaction between the heart and brain is complex and integral to the maintenance of normal cardiovascular function. Even in the absence of coronary disease, acute neuronal injury can induce a variety of cardiac changes. Recent neuroimaging data revealed a network including the insular cortex, anterior cingulate gyrus, and amygdala playing a crucial role in the regulation of central autonomic nervous system. Damage in these areas has been associated with arrhythmia, myocardial injury, higher plasma levels of brain natriuretic peptide, catecholamines, and glucose. Some patients after brain injury may die due to occult cardiac damage and functional impairment in the acute phase. Heart failure adversely influences acute stroke mortality. Troponin and NT-proBNP are elevated in acute brain injury patients, in response to the activated renin–angiotensin–aldosterone system and other neurohumoral changes, as a protective mechanism for sympathoinhibitory activity. Such patients have been shown to be associated with higher short- and long-term mortality. While thrombolysis, neuroprotection, and other measures, alone or in combination, may limit the cerebral damage, attention should also be directed toward the myocardial protection. Early administration of cardioprotective medication aimed at reducing increased sympathetic tone may have a role in myocardial protection in stroke patients. For a full understanding of the brain–heart control, the consequences of disruption of this control, the true incidence of cardiac effects of stroke, and the evidence-based treatment options further research are needed.
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Affiliation(s)
- Ramachandran Gopinath
- Department of Anesthesiology and Intensive Care, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India
| | - Syama Sundar Ayya
- Department of Anesthesiology and Intensive Care, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India
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Nicoletti F, Orlando R, Di Menna L, Cannella M, Notartomaso S, Mascio G, Iacovelli L, Matrisciano F, Fazio F, Caraci F, Copani A, Battaglia G, Bruno V. Targeting mGlu Receptors for Optimization of Antipsychotic Activity and Disease-Modifying Effect in Schizophrenia. Front Psychiatry 2019; 10:49. [PMID: 30890967 PMCID: PMC6413697 DOI: 10.3389/fpsyt.2019.00049] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 01/23/2019] [Indexed: 01/03/2023] Open
Abstract
Metabotropic glutamate (mGlu) receptors are considered as candidate drug targets for the treatment of schizophrenia. These receptors form a family of eight subtypes (mGlu1 to -8), of which mGlu1 and -5 are coupled to Gq/11, and all other subtypes are coupled to Gi/o. Here, we discuss the possibility that selective ligands of individual mGlu receptor subtypes may be effective in controlling the core symptoms of schizophrenia, and, in some cases, may impact mechanisms underlying the progression of the disorder. Recent evidence indicates that activation of mGlu1 receptors inhibits dopamine release in the meso-striatal system. Hence, selective positive allosteric modulators (PAMs) of mGlu1 receptors hold promise for the treatment of positive symptoms of schizophrenia. mGlu5 receptors are widely expressed in the CNS and regulate the activity of cells that are involved in the pathophysiology of schizophrenia, such as cortical GABAergic interneurons and microglial cells. mGlu5 receptor PAMs are under development for the treatment of schizophrenia and cater the potential to act as disease modifiers by restraining neuroinflammation. mGlu2 receptors have attracted considerable interest because they negatively modulate 5-HT2A serotonin receptor signaling in the cerebral cortex. Both mGlu2 receptor PAMs and orthosteric mGlu2/3 receptor agonists display antipsychotic-like activity in animal models, and the latter drugs are inactive in mice lacking mGlu2 receptors. So far, mGlu3 receptors have been left apart as drug targets for schizophrenia. However, activation of mGlu3 receptors boosts mGlu5 receptor signaling, supports neuronal survival, and drives microglial cells toward an antiinflammatory phenotype. This strongly encourages research of mGlu3 receptors in schizophrenia. Finally, preclical studies suggest that mGlu4 receptors might be targeted by novel antipsychotic drugs, whereas studies of mGlu7 and mGlu8 receptors in animal models of psychosis are still at their infancy.
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Affiliation(s)
- Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
| | - Rosamaria Orlando
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | | | | | | | | | - Luisa Iacovelli
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Francesco Matrisciano
- Department of Psychiatry, The Psychiatric Institute, College of Medicine, University of Illinois, Chicago, IL, United States
| | | | - Filippo Caraci
- Department of Drug Sciences, University of Catania, Catania, Italy.,Oasi Research Institute (IRCCS), Troina, Italy
| | - Agata Copani
- Department of Drug Sciences, University of Catania, Catania, Italy.,Institute of Biostructure and Bioimaging, National Research Council, Catania, Italy
| | | | - Valeria Bruno
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
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6
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Ban MJ, Byeon HK, Yang YJ, An S, Kim JW, Kim JH, Kim DH, Yang J, Kee H, Koh YW. Fibroblast growth factor receptor 3-mediated reactivation of ERK signaling promotes head and neck squamous cancer cell insensitivity to MEK inhibition. Cancer Sci 2018; 109:3816-3825. [PMID: 30343534 PMCID: PMC6272115 DOI: 10.1111/cas.13839] [Citation(s) in RCA: 10] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 09/25/2018] [Accepted: 10/09/2018] [Indexed: 12/22/2022] Open
Abstract
Recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) has been a longstanding challenge for head and neck oncologists, and current treatments still have limited efficacy. ERK is aberrantly overexpressed and activated in HNSCC. Herein, we aimed to investigate the cause of the limited therapeutic effect of selumetinib, a selective inhibitor of MEK in HNSCC, as MEK/ERK reactivation inevitably occurs. We assessed the effects of combining selumetinib with fibroblast growth factor receptor 3 (FGFR3) inhibitor (PD173074) on tumor growth. Selumetinib transiently inhibited MAPK signaling and reactivated ERK signaling in HNSCC cells. Rebound in the ERK and Akt pathways in HNSCC cells was accompanied by increased FGFR3 signaling after selumetinib treatment. Feedback activation of FGFR3 was a result of autocrine secretion of the FGF2 ligand. The FGFR3 inhibitor PD173074 prevented MAPK rebound and sensitized the response of HNSCC cells to selumetinib. These results provided rational therapeutic strategies for clinical studies of this subtype of patients that show a poor prognosis with selumetinib. Our data provide a rationale for combining a MEK inhibitor with inhibitors of feedback activation of FGFR3 signaling in HNSCC cells. ERK rebound as a result of the upregulation of FGFR3 and the ligand FGF2 diminished the antitumor effects of selumetinib, which was overcome by combination treatment with the FGFR3 inhibitor.
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Affiliation(s)
- Myung Jin Ban
- Department of Otorhinolaryngology-Head and Neck Surgery, Soonchunhyang University College of Medicine, Cheonan, Korea.,Department of Medicine, The Graduate School of Yonsei University, Seoul, Korea
| | - Hyung Kwon Byeon
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea
| | - Yeon Ju Yang
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
| | - Sojung An
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
| | - Jae Wook Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Soonchunhyang University College of Medicine, Cheonan, Korea
| | - Ji-Hoon Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Da Hee Kim
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
| | - Jaemoon Yang
- Department of Radiology, Yonsei University College of Medicine, Seoul, Korea.,Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea
| | - Hyunjung Kee
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
| | - Yoon Woo Koh
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea.,The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Korea
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7
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Krieger CC, Morgan SJ, Neumann S, Gershengorn MC. Thyroid Stimulating Hormone (TSH)/Insulin-like Growth Factor 1 (IGF1) Receptor Cross-talk in Human Cells. Curr Opin Endocr Metab Res 2018; 2:29-33. [PMID: 30547142 PMCID: PMC6287758 DOI: 10.1016/j.coemr.2018.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thyroid stimulating hormone and insulin-like growth factor 1 receptors (TSHRs and IGF1Rs, respectively) interact leading to additive or synergistic stimulation of cellular responses. Recent findings provide evidence that the interaction between TSHRs and IGF1Rs is similar to that described for other G protein-coupled receptors and receptor tyrosine kinases. These types of interactions occur at or proximal to the receptors and are designated "receptor cross-talk." Herein, we describe our studies in human thyrocytes, human retro-orbital fibroblasts from Graves' orbitopathy patients and a model cell line that support the concept of TSHR/IGF1R cross-talk. We also discuss how receptor cross-talk is involved in stimulation by a monoclonal TSHR-stimulating antibody and how targeting both receptors may lead to novel treatments of Graves' orbitopathy.
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Affiliation(s)
- Christine C. Krieger
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Sarah J. Morgan
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Marvin C. Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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8
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Tóth AD, Turu G, Hunyady L, Balla A. Novel mechanisms of G-protein-coupled receptors functions: AT 1 angiotensin receptor acts as a signaling hub and focal point of receptor cross-talk. Best Pract Res Clin Endocrinol Metab 2018; 32:69-82. [PMID: 29678287 DOI: 10.1016/j.beem.2018.02.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AT1 angiotensin receptor (AT1R), a prototypical G protein-coupled receptor (GPCR), is the main receptor, which mediates the effects of the renin-angiotensin system (RAS). AT1R plays a crucial role in the regulation of blood pressure and salt-water homeostasis, and in the development of pathological conditions, such as hypertension, heart failure, cardiovascular remodeling, renal fibrosis, inflammation, and metabolic disorders. Stimulation of AT1R leads to pleiotropic signal transduction pathways generating arrays of complex cellular responses. Growing amount of evidence shows that AT1R is a versatile GPCR, which has multiple unique faces with distinct conformations and signaling properties providing new opportunities for functionally selective pharmacological targeting of the receptor. Biased ligands of AT1R have been developed to selectively activate the β-arrestin pathway, which may have therapeutic benefits compared to the conventional angiotensin converting enzyme inhibitors and angiotensin receptor blockers. In this review, we provide a summary about the most recent findings and novel aspects of the AT1R function, signaling, regulation, dimerization or oligomerization and its cross-talk with other receptors, including epidermal growth factor (EGF) receptor, adrenergic receptors and CB1 cannabinoid receptor. Better understanding of the mechanisms and structural aspects of AT1R activation and cross-talk can lead to the development of novel type of drugs for the treatment of cardiovascular and other diseases.
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Affiliation(s)
- András D Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gábor Turu
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary.
| | - András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
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Mazzeo AT, Micalizzi A, Mascia L, Scicolone A, Siracusano L. Brain-heart crosstalk: the many faces of stress-related cardiomyopathy syndromes in anaesthesia and intensive care. Br J Anaesth 2014; 112:803-15. [PMID: 24638232 DOI: 10.1093/bja/aeu046] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Neurogenic stress cardiomyopathy (NSC) is a well-known syndrome complicating the early phase after an acute brain injury, potentially affecting outcomes. This article is a review of recent data on the putative role of localization and lateralization of brain lesions in NSC, cardiac innervation abnormalities, and new polymorphisms and other genetic causes of the sympathetic nervous system over-activity. Concerns regarding the management of stress-related cardiomyopathy syndromes during the perioperative period are also discussed. Future clinical research should explore whether specific factors explain different patient susceptibilities to the disease and should be directed towards early identification and stratification of patients at risk, so that such patients can be more carefully monitored and appropriately managed in critical care and during the perioperative period.
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Affiliation(s)
- A T Mazzeo
- Department of Anaesthesia and Intensive Care, University of Torino, Azienda Ospedaliera Citta' della Salute e della Scienza di Torino, Presidio Molinette, Corso Dogliotti 14, 10126 Torino, Italy
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10
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George AJ, Hannan RD, Thomas WG. Unravelling the molecular complexity of GPCR-mediated EGFR transactivation using functional genomics approaches. FEBS J 2013; 280:5258-68. [PMID: 23992425 DOI: 10.1111/febs.12509] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [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: 05/14/2013] [Revised: 08/20/2013] [Accepted: 08/23/2013] [Indexed: 02/06/2023]
Abstract
To influence physiology and pathophysiology, G protein-coupled receptors (GPCRs) have evolved to appropriate additional signalling modalities, such as activation of adjacent membrane receptors. Epidermal growth factor receptors (EGFRs) mediate growth and remodelling actions of GPCRs, although the precise network of gene products and molecular cascades linking GPCRs to EGFRs (termed EGFR transactivation) remains incomplete. In this review, we describe the current view of GPCR-EGFR transactivation, identifying the established models of receptor cross-talk. We consider the limitations in our current knowledge, and propose that recent advances in molecular and cell biology technology, including functional genomics approaches, will allow a renewed focus of efforts to understand the mechanism underlying EGFR transactivation. Using an unbiased approach for identification of the molecules required for GPCR-mediated EGFR transactivation will provide a contemporary and more complete representation from which to extrapolate therapeutic control in diseases from cardiovascular remodelling to cancer.
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Affiliation(s)
- Amee J George
- School of Biomedical Sciences, The University of Queensland, St Lucia, Qld, Australia; Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Vic., Australia; Department of Pathology, The University of Melbourne, Parkville, Vic., Australia
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11
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Abstract
The ‘omnipresence’ of adenosine in all nervous system cells (neurons and glia) together with the intensive release of adenosine following insults, makes adenosine as a sort of ‘maestro’ of synapses leading to the homeostatic coordination of brain function. Besides direct actions of adenosine on the neurosecretory mechanisms, where adenosine operates to tune neurotransmitter release, receptor-receptor interactions as well as interplays between adenosine receptors and transporters occur as part of the adenosine’s attempt to fine tuning synaptic transmission. This review will focus on the different ways adenosine can use to trigger or brake the action of several neurotransmitters and neuromodulators. Adenosine receptors cross talk with other G protein coupled receptors (GPCRs), with ionotropic receptors and with receptor kinases. Most of these interactions occur through A2A receptors, which in spite their low density in some brain areas, such as the hippocampus, may function as metamodulators. Tonic adenosine A2A receptor activity is a required step to allow synaptic actions of neurotrophic factors, namely upon synaptic transmission at both pre- and post-synaptic level as well as upon synaptic plasticity and neuronal survival. The implications of these interactions in normal brain functioning and in neurologic and psychiatric dysfunction will be discussed.
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Affiliation(s)
- A M Sebastião
- Institute of Pharmacology and Neurosciences, Faculty of Medicine and Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisboa, Portugal.
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12
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Iba K, Albrechtsen R, Gilpin B, Fröhlich C, Loechel F, Zolkiewska A, Ishiguro K, Kojima T, Liu W, Langford JK, Sanderson RD, Brakebusch C, Fässler R, Wewer UM. The cysteine-rich domain of human ADAM 12 supports cell adhesion through syndecans and triggers signaling events that lead to beta1 integrin-dependent cell spreading. J Cell Biol 2000; 149:1143-56. [PMID: 10831617 PMCID: PMC2174829 DOI: 10.1083/jcb.149.5.1143] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.9] [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] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ADAMs (a disintegrin and metalloprotease) family of proteins is involved in a variety of cellular interactions, including cell adhesion and ecto- domain shedding. Here we show that ADAM 12 binds to cell surface syndecans. Three forms of recombinant ADAM 12 were used in these experiments: the cys-teine-rich domain made in Escherichia coli (rADAM 12-cys), the disintegrin-like and cysteine-rich domain made in insect cells (rADAM 12-DC), and full-length human ADAM 12-S tagged with green fluorescent protein made in mammalian cells (rADAM 12-GFP). Mesenchymal cells specifically and in a dose-dependent manner attach to ADAM 12 via members of the syndecan family. After binding to syndecans, mesenchymal cells spread and form focal adhesions and actin stress fibers. Integrin beta1 was responsible for cell spreading because function-blocking monoclonal antibodies completely inhibited cell spreading, and chondroblasts lacking beta1 integrin attached but did not spread. These data suggest that mesenchymal cells use syndecans as the initial receptor for the ADAM 12 cysteine-rich domain-mediated cell adhesion, and then the beta1 integrin to induce cell spreading. Interestingly, carcinoma cells attached but did not spread on ADAM 12. However, spreading could be efficiently induced by the addition of either 1 mM Mn(2+) or the beta1 integrin-activating monoclonal antibody 12G10, suggesting that in these carcinoma cells, the ADAM 12-syndecan complex fails to modulate the function of beta1 integrin.
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Affiliation(s)
- Kousuke Iba
- The Institute of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Reidar Albrechtsen
- The Institute of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Brent Gilpin
- The Institute of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Camilla Fröhlich
- The Institute of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Frosty Loechel
- The Institute of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Anna Zolkiewska
- Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506
| | - Kazuhiro Ishiguro
- Department of Medical Technology, School of Health Sciences, and First Department of Internal Medicine, Nagoya University, Nagoya 466-8550, Japan
| | - Tetsuhito Kojima
- Department of Medical Technology, School of Health Sciences, and First Department of Internal Medicine, Nagoya University, Nagoya 466-8550, Japan
| | - Wei Liu
- The Department of Pathology, Arkansas Cancer Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - J. Kevin Langford
- The Department of Pathology, Arkansas Cancer Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Ralph D. Sanderson
- The Department of Pathology, Arkansas Cancer Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Cord Brakebusch
- Department of Experimental Pathology, Lund University, Lund 22185, Sweden
| | - Reinhard Fässler
- Department of Experimental Pathology, Lund University, Lund 22185, Sweden
| | - Ulla M. Wewer
- The Institute of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
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13
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Reynen PH, Martin GR, Eglen RM, MacLennan SJ. Characterization of human recombinant alpha(2A)-adrenoceptors expressed in Chinese hamster lung cells using intracellular Ca(2+) changes: evidence for cross-talk between recombinant alpha(2A)- and native alpha(1)-adrenoceptors. Br J Pharmacol 2000; 129:1339-46. [PMID: 10742289 PMCID: PMC1571968 DOI: 10.1038/sj.bjp.0703184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [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] [Indexed: 11/09/2022] Open
Abstract
1. Human alpha(2A)-adrenoceptors expressed in Chinese hamster lung (CHL) fibroblasts have been pharmacologically characterized by measuring intracellular calcium (Ca(2+)(i)) changes using the Ca(2+)-sensitive dye Fluo3-AM, in conjunction with a fluorometric imaging plate reader (FLIPR). 2. Several alpha-adrenoceptor agonists were examined including the alpha(2)-adrenoceptor agonists UK-14304, B-HT 920, dexmedetomidine and A-54741, the selective alpha(1)-adrenoceptor agonist phenylephrine and the non-selective adrenergic agonist noradrenaline. Of these only noradrenaline (mean pEC(50)=6.49) and A-54741 (6.90) evoked changes in Ca(2+)(i); A-54741 was a partial agonist relative to noradrenaline, achieving only 33% of the noradrenaline maximum. 3. Ca(2+)(i) changes induced by noradrenaline and A-54741 were antagonized by the alpha(2)-selective antagonist rauwolscine (10 nM) and by the alpha(1)-selective antagonists prazosin (0.1 nM) and doxazosin (1.0 nM). 4. Phenylephrine (100 microM) and UK-14304 (10 microM) alone were ineffective in causing Ca(2+)(i) increase. In the presence of a fixed concentration of UK-14304 (3.0 microM), phenylephrine induced concentration-dependent increases in Ca(2+)(i) (mean pEC(50)=5.33). In the presence of phenylephrine (30.0 microM) UK-14304 induced Ca(2+)(i) release (pEC(50)=6.92). The effects of phenylephrine were abolished by prazosin (1.0 nM) or rauwolscine (100 nM). 5. In saturation radioligand binding experiments using membranes of parental (non-transfected) CHL cells there was a small, specific binding of [(3)H]-prazosin (B(max)=24 fmol mg protein(-1); pK(D)=10. 24). 6. Collectively, these data suggest that alpha-adrenoceptor agonist-induced Ca(2+)(i) release in CHL fibroblasts transfected with the human alpha(2A)-adrenoceptor is dependent upon co-activation of the recombinant receptor and a native alpha(1)-adrenoceptor.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Aniline Compounds
- Animals
- Azepines/pharmacology
- Binding, Competitive
- Brimonidine Tartrate
- Calcium/metabolism
- Cell Line
- Cricetinae
- Dexmedetomidine/pharmacology
- Dose-Response Relationship, Drug
- Doxazosin/pharmacology
- Estrenes/pharmacology
- Fluorescence
- Gene Expression
- Humans
- Imidazoles/pharmacology
- Norepinephrine/pharmacology
- Prazosin/metabolism
- Prazosin/pharmacology
- Pyrrolidinones/pharmacology
- Quinoxalines/pharmacology
- Radioligand Assay
- Receptor Cross-Talk
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Recombinant Fusion Proteins/drug effects
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction/drug effects
- Tetrahydronaphthalenes/pharmacology
- Thapsigargin/pharmacology
- Xanthenes
- Yohimbine/pharmacology
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Affiliation(s)
- P H Reynen
- Department of Molecular Pharmacology, Center for Biological Research, Neurobiology Unit, Roche Bioscience, 3401 Hillview Avenue, Palo Alto, California, CA 94304, U.S.A
| | - G R Martin
- Department of Molecular Pharmacology, Center for Biological Research, Neurobiology Unit, Roche Bioscience, 3401 Hillview Avenue, Palo Alto, California, CA 94304, U.S.A
| | - R M Eglen
- Department of Molecular Pharmacology, Center for Biological Research, Neurobiology Unit, Roche Bioscience, 3401 Hillview Avenue, Palo Alto, California, CA 94304, U.S.A
| | - S J MacLennan
- Department of Molecular Pharmacology, Center for Biological Research, Neurobiology Unit, Roche Bioscience, 3401 Hillview Avenue, Palo Alto, California, CA 94304, U.S.A
- Author for correspondence:
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14
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Thomas DR, Middlemiss DN, Taylor SG, Nelson P, Brown AM. 5-CT stimulation of adenylyl cyclase activity in guinea-pig hippocampus: evidence for involvement of 5-HT7 and 5-HT1A receptors. Br J Pharmacol 1999; 128:158-64. [PMID: 10498847 PMCID: PMC1571602 DOI: 10.1038/sj.bjp.0702759] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [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] [Indexed: 11/08/2022] Open
Abstract
1. A number of compounds, including the selective 5-HT7 receptor antagonist SB-258719, were investigated for their effect on [3H]-5-carboxamidotryptamine (5-CT) radioligand binding and 5-CT-stimulated adenylyl cyclase activity in guinea-pig hippocampal membranes, in order to confirm the presence of functionally coupled 5-HT7 receptors in this tissue. 2. The [3H]-5-CT radioligand binding profile was consistent with binding predominantly to 5-HT7 receptors. The affinity of SB-258719 (pKi 7.2+/-0.1) was similar to its reported human 5-HT7 receptor affinity. 3. In the adenylyl cyclase functional assay, 5-CT was a potent and full agonist compared to 5-HT, whereas 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) was a partial agonist (intrinsic activity 0.4+/-0.1). The rank order of potency for agonists (5-CT>5-HT approximately 8-OH-DPAT) was consistent with activation of 5-HT7 receptors. SB-258719 (5 microM) and methiothepin (1 microM) surmountably antagonized the response to 5-CT, consistent with competitive antagonism. The pKB for SB-258719 (7.2+/-0.1) was in good agreement with its reported antagonist potency at the human cloned 5-HT7 receptor. 4. In the functional assay, WAY-100635 (100 nM) and cyanopindolol (1 microM) induced a biphasic 5-CT response curve, consistent with selective antagonism of a component of the response to 5-CT. The estimated pKB values for WAY-100635 and cyanopindolol (9.6 and 8.4 respectively) were in good agreement with their reported 5-HT1A receptor affinities. 5. The data are consistent with the presence of 5-HT7 receptors in guinea-pig hippocampus which are positively coupled to adenylyl cyclase. In addition, 5-HT7 receptor-mediated stimulation of adenylyl cyclase activity in this tissue appears to be augmented by a mechanism involving 5-HT1A receptor activation.
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Affiliation(s)
- D R Thomas
- Department of Neuroscience Research, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW. David
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15
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Aley KO, Levine JD. Multiple receptors involved in peripheral alpha 2, mu, and A1 antinociception, tolerance, and withdrawal. J Neurosci 1997; 17:735-44. [PMID: 8987795 PMCID: PMC6573239] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We examined the interactions among three classes of peripherally-acting antinociceptive agents (mu-opioid, alpha 2-adrenergic, and A1-adenosine) in the development of tolerance and dependence to their antinociceptive effects. Antinociception was determined by assessing the degree of inhibition of prostaglandin E2 (PGE2)-induced mechanical hyperalgesia, using the Randall-Selitto paw-withdrawal test. Tolerance developed within 4 hr to the antinociceptive effect of the alpha 2-adrenergic agonist clonidine; dependence also occurred at that time, demonstrated as a withdrawal hyperalgesia that was precipitated by the alpha 2-receptor antagonist yohimbine. These findings are similar to those reported previously for tolerance and dependence to mu and A1 peripheral antinociception (Aley et al., 1995). Furthermore, cross-tolerance and cross-withdrawal between mu, A1, and alpha 2 agonists occurred. The observations of cross-tolerance and cross-withdrawal suggest that all three receptors are located on the same primary afferent nociceptors. In addition, the observations suggest that the mechanisms of tolerance and dependence to the antinociceptive effects of mu, A1, and alpha 2 are mediated by a common mechanism. Although any of the agonists administered alone produce antinociception, we found that mu, A1, and alpha 2 receptors may not act independently to produce antinociception, but rather may require the physical presence of the other receptors to produce antinociception by any one agonist. This was suggested by the finding that clonidine (alpha 2-agonist) antinociception was blocked not only by yohimbine (alpha 2-antagonist) but also by PACPX (A1-antagonist) and by naloxone (mu-antagonist), and that DAMGO (mu-agonist) antinociception and CPA (A1-agonist) antinociception were blocked not only by naloxone (mu-antagonist) and PACPX (A1-antagonist), respectively, but also by yohimbine (alpha 2-antagonist). This cross-antagonism of antinociception occurred at the ID50 dose for each antagonist at its homologous receptor. To test the hypothesis that the physical presence of mu-opioid receptor is required not only for mu antinociception but also for alpha 2 antinociception, antisense oligodeoxynucleotides (ODNs) for the mu-opioid and alpha 2C-adrenergic receptors were administered intrathecally to reduce the expression of these receptors on primary afferent neurons. These studies demonstrated that mu-opioid ODN administration decreased not only mu-opioid but also alpha 2-adrenergic antinociception; A1 antinociception was unaffected. In contrast, alpha 2C-adrenergic ODN decreased antinociception induced by all three classes of antinociceptive agents. In conclusion, these data suggest that peripheral antinociception induced by mu, alpha 2, and A1 agonists requires the physical presence of multiple receptors. We propose that there is a mu, A1, alpha 2 receptor complex mediating antinociception in the periphery. In addition, there is cross-tolerance and cross-dependence between mu, A1, and alpha 2 antinociception, suggesting that their underlying mechanisms are related.
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MESH Headings
- Adenosine/analogs & derivatives
- Adenosine/pharmacology
- Adrenergic alpha-2 Receptor Agonists
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic alpha-Agonists/therapeutic use
- Adrenergic alpha-Antagonists/pharmacology
- Adrenergic alpha-Antagonists/therapeutic use
- Adrenergic alpha-Antagonists/toxicity
- Analgesics/pharmacology
- Analgesics/therapeutic use
- Analgesics, Opioid/pharmacology
- Animals
- Clonidine/pharmacology
- Clonidine/therapeutic use
- Dinoprostone/pharmacology
- Dinoprostone/physiology
- Drug Interactions
- Drug Tolerance
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalins/pharmacology
- Hyperalgesia/chemically induced
- Hyperalgesia/drug therapy
- Hyperalgesia/physiopathology
- Male
- Models, Biological
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Oligonucleotides, Antisense/pharmacology
- Purinergic P1 Receptor Agonists
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/physiology
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/physiology
- Receptors, Purinergic P1/physiology
- Second Messenger Systems
- Substance Withdrawal Syndrome/etiology
- Substance Withdrawal Syndrome/physiopathology
- Substance-Related Disorders/physiopathology
- Xanthines/pharmacology
- Yohimbine/pharmacology
- Yohimbine/therapeutic use
- Yohimbine/toxicity
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Affiliation(s)
- K O Aley
- Department of Anatomy, University of California at San Francisco 94143-0452, USA
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