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Anthofer L, Gmach P, Uretmen Kagiali ZC, Kleinau G, Rotter J, Opitz R, Scheerer P, Beck-Sickinger AG, Wolf P, Biebermann H, Bechmann I, Kühnen P, Krude H, Paisdzior S. Melanocortin-4 Receptor PLC Activation Is Modulated by an Interaction with the Monocarboxylate Transporter 8. Int J Mol Sci 2024; 25:7565. [PMID: 39062808 PMCID: PMC11277258 DOI: 10.3390/ijms25147565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/05/2024] [Accepted: 07/06/2024] [Indexed: 07/28/2024] Open
Abstract
The melanocortin-4 receptor (MC4R) is a key player in the hypothalamic leptin-melanocortin pathway that regulates satiety and hunger. MC4R belongs to the G protein-coupled receptors (GPCRs), which are known to form heterodimers with other membrane proteins, potentially modulating receptor function or characteristics. Like MC4R, thyroid hormones (TH) are also essential for energy homeostasis control. TH transport across membranes is facilitated by the monocarboxylate transporter 8 (MCT8), which is also known to form heterodimers with GPCRs. Based on the finding in single-cell RNA-sequencing data that both proteins are simultaneously expressed in hypothalamic neurons, we investigated a putative interplay between MC4R and MCT8. We developed a novel staining protocol utilizing a fluorophore-labeled MC4R ligand and demonstrated a co-localization of MC4R and MCT8 in human brain tissue. Using in vitro assays such as BRET, IP1, and cAMP determination, we found that MCT8 modulates MC4R-mediated phospholipase C activation but not cAMP formation via a direct interaction, an effect that does not require a functional MCT8 as it was not altered by a specific MCT8 inhibitor. This suggests an extended functional spectrum of MCT8 as a GPCR signaling modulator and argues for the investigation of further GPCR-protein interactions with hitherto underrepresented physiological functions.
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Affiliation(s)
- Larissa Anthofer
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
- Institute of Anatomy, Leipzig University, D-04103 Leipzig, Germany
| | - Philipp Gmach
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Zeynep Cansu Uretmen Kagiali
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Gunnar Kleinau
- Group Structural Biology of Cellular Signaling, Institute of Medical Physics and Biophysics, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Jonas Rotter
- Institute of Anatomy, Leipzig University, D-04103 Leipzig, Germany
| | - Robert Opitz
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Patrick Scheerer
- Group Structural Biology of Cellular Signaling, Institute of Medical Physics and Biophysics, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | | | - Philipp Wolf
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, D-04103 Leipzig, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, D-04103 Leipzig, Germany
| | - Peter Kühnen
- Department for Pediatric Endocrinology and Diabetology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Sarah Paisdzior
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
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2
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Mezei M, Latif R, Davies TF. The full-length TSH receptor is stabilized by TSH ligand. J Mol Graph Model 2024; 129:108725. [PMID: 38373379 DOI: 10.1016/j.jmgm.2024.108725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/24/2024] [Accepted: 02/08/2024] [Indexed: 02/21/2024]
Abstract
The receptor for thyroid stimulating hormone (TSHR), a GPCR, is the primary antigen in autoimmune hyperthyroidism (Graves' disease) caused by stimulating TSHR antibodies. While we have previously published a full length model of the TSHR, including its leucine rich domain (LRD), linker region (LR) and transmembrane domain (TMD), to date, only a partial LRD (aa 21-261) stabilized with TSHR autoantibodies has been crystallized. Recently, however, cryo-EM structures of the full-length TSHR have been published but they include only an incomplete LR. We have now utilized the cryo-EM models, added disulfide bonds to the LR and performed longer (3000 ns) molecular dynamic (MD) simulations to update our previous model of the entire full-length TSHR, with and without the presence of TSH ligand. As in our earlier work, the new model was embedded in a lipid membrane and was solvated with water and counterions. We found that the 3000 ns Molecular Dynamic simulations showed that the structure of the LRD and TMD were remarkably constant while the LR, known more commonly as the "hinge region", again showed significant flexibility, forming several transient secondary structural elements. Analysis of the new simulations permitted a detailed examination of the effect of TSH binding on the structure of the TSHR. We found a structure-stabilizing effect of TSH, including increased stability of the LR, which was clearly demonstrated by analyzing several intrinsic receptor properties including hydrogen bonding, fluctuation of the LRD orientation, and radius of gyration. In conclusion, we were able to quantify the flexibility of the TSHR and show its increased stability after TSH binding. These data indicated the important role of ligands in directing the signaling structure of a receptor.
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Affiliation(s)
- Mihaly Mezei
- Department of Pharmacological Sciences, New York, NY, USA; Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Rauf Latif
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA; James J. Peters VA Medical Center, New York, NY, USA
| | - Terry F Davies
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA; James J. Peters VA Medical Center, New York, NY, USA
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3
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Velloso JPL, Kovacs AS, Pires DEV, Ascher DB. AI-driven GPCR analysis, engineering, and targeting. Curr Opin Pharmacol 2024; 74:102427. [PMID: 38219398 DOI: 10.1016/j.coph.2023.102427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/16/2024]
Abstract
This article investigates the role of recent advances in Artificial Intelligence (AI) to revolutionise the study of G protein-coupled receptors (GPCRs). AI has been applied to many areas of GPCR research, including the application of machine learning (ML) in GPCR classification, prediction of GPCR activation levels, modelling GPCR 3D structures and interactions, understanding G-protein selectivity, aiding elucidation of GPCRs structures, and drug design. Despite progress, challenges in predicting GPCR structures and addressing the complex nature of GPCRs remain, providing avenues for future research and development.
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Affiliation(s)
- João P L Velloso
- Structural Biology and Bioinformatics, Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Victoria, Australia; Systems and Computational Biology, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia; Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Aaron S Kovacs
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Douglas E V Pires
- Structural Biology and Bioinformatics, Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Victoria, Australia; Systems and Computational Biology, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia; Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia; School of Computing and Information Systems, University of Melbourne, Melbourne, Victoria, Australia.
| | - David B Ascher
- Structural Biology and Bioinformatics, Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Victoria, Australia; Systems and Computational Biology, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia; Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.
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4
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Chandrasekar A, Schmidtlein PM, Neve V, Rivagorda M, Spiecker F, Gauthier K, Prevot V, Schwaninger M, Müller-Fielitz H. Regulation of Thyroid Hormone Gatekeepers by Thyrotropin in Tanycytes. Thyroid 2024; 34:261-273. [PMID: 38115594 DOI: 10.1089/thy.2023.0375] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Background: Tanycytes are specialized glial cells within the mediobasal hypothalamus that have multiple functions, including hormone sensing and regulation of hypophysiotropic hormone secretion. There are ongoing discussions about the role of tanycytes in regulating the supply of hypothalamic thyroid hormones (THs) through the expression of TH transporters (Slc16a2, Slco1c1) and deiodinases (Dio2, Dio3). In this study, we investigated the potential feedback effect of thyrotropin (TSH) on the transcription of these gatekeeper genes on tanycytes. Methods: We analyzed the changes in the expression of TH-gatekeeper genes, in TSH-stimulated primary tanycytes, using quantitative polymerase chain reaction (qPCR). We also used RNAScope® in brain slices to further reveal the local distribution of the transcripts. In addition, we blocked intracellular pathways and used small-interfering RNA (siRNA) to elucidate differences in the regulation of the gatekeeper genes. Results: TSH elevated messenger RNA (mRNA) levels of Slco1c1, Dio2, and Dio3 in tanycytes, while Slc16a2 was mostly unaffected. Blockade and knockdown of the TSH receptor (TSHR) and antagonization of cAMP response element-binding protein (CREB) clearly abolished the increased expression induced by TSH, indicating PKA-dependent regulation through the TSHR. The TSH-dependent expression of Dio3 and Slco1c1 was also regulated by protein kinase C (PKC), and in case of Dio3, also by extracellular signal-regulated kinase (ERK) activity. Importantly, these gene regulations were specifically found in different subpopulations of tanycytes. Conclusions: This study demonstrates that TSH induces transcriptional regulation of TH-gatekeeper genes in tanycytes through the Tshr/Gαq/PKC pathway, in parallel to the Tshr/Gαs/PKA/CREB pathway. These differential actions of TSH on tanycytic subpopulations appear to be important for coordinating the supply of TH to the hypothalamus and aid its functions.
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Affiliation(s)
- Akila Chandrasekar
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
| | - Paula Marie Schmidtlein
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
| | - Vanessa Neve
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
| | - Manon Rivagorda
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
| | - Frauke Spiecker
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
| | - Karine Gauthier
- ENS de Lyon, INRAE, CNRS, Institut de Génomique Fonctionnelle de Lyon, University of Lyon, Lyon, France
| | - Vincent Prevot
- Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S 1172, European Genomic Institute for Diabetes (EGID), University of Lille, Lille, France
| | - Markus Schwaninger
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
- DZHK (German Research Centre for Cardiovascular Research), Hamburg-Lübeck-Kiel, Lübeck, Germany
| | - Helge Müller-Fielitz
- Institute for Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
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5
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Makkonen K, Jännäri M, Crisóstomo L, Kuusi M, Patyra K, Melnyk V, Linnossuo V, Ojala J, Ravi R, Löf C, Mäkelä JA, Miettinen P, Laakso S, Ojaniemi M, Jääskeläinen J, Laakso M, Bossowski F, Sawicka B, Stożek K, Bossowski A, Kleinau G, Scheerer P, FinnGen F, Reeve MP, Kero J. Mechanisms of thyrotropin receptor-mediated phenotype variability deciphered by gene mutations and M453T-knockin model. JCI Insight 2024; 9:e167092. [PMID: 38194289 PMCID: PMC11143923 DOI: 10.1172/jci.insight.167092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/05/2024] [Indexed: 01/10/2024] Open
Abstract
The clinical spectrum of thyrotropin receptor-mediated (TSHR-mediated) diseases varies from loss-of-function mutations causing congenital hypothyroidism to constitutively active mutations (CAMs) leading to nonautoimmune hyperthyroidism (NAH). Variation at the TSHR locus has also been associated with altered lipid and bone metabolism and autoimmune thyroid diseases. However, the extrathyroidal roles of TSHR and the mechanisms underlying phenotypic variability among TSHR-mediated diseases remain unclear. Here we identified and characterized TSHR variants and factors involved in phenotypic variability in different patient cohorts, the FinnGen database, and a mouse model. TSHR CAMs were found in all 16 patients with NAH, with 1 CAM in an unexpected location in the extracellular leucine-rich repeat domain (p.S237N) and another in the transmembrane domain (p.I640V) in 2 families with distinct hyperthyroid phenotypes. In addition, screening of the FinnGen database revealed rare functional variants as well as distinct common noncoding TSHR SNPs significantly associated with thyroid phenotypes, but there was no other significant association between TSHR variants and more than 2,000 nonthyroid disease endpoints. Finally, our TSHR M453T-knockin model revealed that the phenotype was dependent on the mutation's signaling properties and was ameliorated by increased iodine intake. In summary, our data show that TSHR-mediated disease risk can be modified by variants at the TSHR locus both inside and outside the coding region as well as by altered TSHR-signaling and dietary iodine, supporting the need for personalized treatment strategies.
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Affiliation(s)
- Kristiina Makkonen
- Department of Clinical Sciences, Faculty of Medicine, and
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Meeri Jännäri
- Department of Clinical Sciences, Faculty of Medicine, and
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Luís Crisóstomo
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Matilda Kuusi
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Konrad Patyra
- Department of Clinical Sciences, Faculty of Medicine, and
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | | | - Veli Linnossuo
- Department of Clinical Sciences, Faculty of Medicine, and
| | - Johanna Ojala
- Department of Clinical Sciences, Faculty of Medicine, and
| | - Rowmika Ravi
- Department of Clinical Sciences, Faculty of Medicine, and
| | - Christoffer Löf
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Juho-Antti Mäkelä
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Päivi Miettinen
- New Children’s Hospital, Helsinki University Hospital, Helsinki, Finland
| | - Saila Laakso
- New Children’s Hospital, Helsinki University Hospital, Helsinki, Finland
| | - Marja Ojaniemi
- Department of Pediatrics and Adolescence, PEDEGO Research Unit and Medical Research Center, University and University Hospital of Oulu, Oulu, Finland
| | | | - Markku Laakso
- Institute of Clinical Medicine, Internal Medicine, University of Eastern Finland, Kuopio, Finland
| | - Filip Bossowski
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Beata Sawicka
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Karolina Stożek
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Artur Bossowski
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Gunnar Kleinau
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, and
- Humboldt - Universität zu Berlin, Institute of Medical Physics, Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, and
- Humboldt - Universität zu Berlin, Institute of Medical Physics, Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - FinnGen FinnGen
- Institute for Molecular Medicine Finland, HiLIFE, University of Helsinki, Helsinki, Finland
- FinnGen is detailed in Supplemental Acknowledgments
| | - Mary Pat Reeve
- Institute for Molecular Medicine Finland, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Jukka Kero
- Department of Clinical Sciences, Faculty of Medicine, and
- Department of Pediatrics and Adolescent Medicine, Turku University Hospital, Turku, Finland
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6
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Latif R, Davies TF, Mezei M. Functional Water Channels Within the TSH Receptor: A New Paradigm for TSH Action With Disease Implications. Endocrinology 2023; 164:bqad146. [PMID: 37767722 DOI: 10.1210/endocr/bqad146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/20/2023] [Accepted: 09/25/2023] [Indexed: 09/29/2023]
Abstract
The thyroid-stimulating hormone receptor (TSHR) transmembrane domain (TMD) is found in the plasma membrane and consists of lipids and water molecules. To understand the role of TSHR-associated water molecules, we used molecular dynamic simulations of the TMD and identified a network of putative receptor-associated transmembrane water channels. This result was confirmed with extended simulations of the full-length TSHR with and without TSH ligand binding. While the transport time observed in the simulations via the TSHR protein was slower than via the lipid bilayer itself, we found that significantly more water traversed via the TSHR than via the lipid bilayer, which more than doubled with the binding of TSH. Using rat thyroid cells (FRTL-5) and a calcein fluorescence technique, we measured cell volumes after blockade of aquaporins 1 and 4, the major thyroid cell water transporters. TSH showed a dose-dependent ability to influence water transport, and similar effects were observed with stimulating TSHR autoantibodies. Small molecule TSHR agonists, which are allosteric activators of the TMD, also enhanced water transport, illustrating the role of the TMD in this phenomenon. Furthermore, the water channel pathway was also mapped across 2 activation motifs within the TSHR TMD, suggesting how water movement may influence activation of the receptor. In pathophysiological conditions such as hypothyroidism and hyperthyroidism where TSH concentrations are highly variable, this action of TSH may greatly influence water movement in thyroid cells and many other extrathyroidal sites where the TSHR is expressed, thus affecting normal cellular function.
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Affiliation(s)
- Rauf Latif
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- James J. Peters VA Medical Center, Thyroid Research Unit, New York, NY 10468, USA
| | - Terry F Davies
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- James J. Peters VA Medical Center, Thyroid Research Unit, New York, NY 10468, USA
| | - Mihaly Mezei
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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7
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Fagin JA, Krishnamoorthy GP, Landa I. Pathogenesis of cancers derived from thyroid follicular cells. Nat Rev Cancer 2023; 23:631-650. [PMID: 37438605 PMCID: PMC10763075 DOI: 10.1038/s41568-023-00598-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/08/2023] [Indexed: 07/14/2023]
Abstract
The genomic simplicity of differentiated cancers derived from thyroid follicular cells offers unique insights into how oncogenic drivers impact tumour phenotype. Essentially, the main oncoproteins in thyroid cancer activate nodes in the receptor tyrosine kinase-RAS-BRAF pathway, which constitutively induces MAPK signalling to varying degrees consistent with their specific biochemical mechanisms of action. The magnitude of the flux through the MAPK signalling pathway determines key elements of thyroid cancer biology, including differentiation state, invasive properties and the cellular composition of the tumour microenvironment. Progression of disease results from genomic lesions that drive immortalization, disrupt chromatin accessibility and cause cell cycle checkpoint dysfunction, in conjunction with a tumour microenvironment characterized by progressive immunosuppression. This Review charts the genomic trajectories of these common endocrine tumours, while connecting them to the biological states that they confer.
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Affiliation(s)
- James A Fagin
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Gnana P Krishnamoorthy
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Iñigo Landa
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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8
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Latif R, Morshed SA, McCann C, Davies TF. Thyroid Stem Cell Speciation-a Major Role for PKC. Endocrinology 2023; 164:bqad067. [PMID: 37120783 DOI: 10.1210/endocr/bqad067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/01/2023]
Abstract
Instructive signals that delineate the formation of thyroid follicles by thyrotropin (TSH) in stem cells are complex. Here, we have examined the role of protein kinase C (PKC) by using a unique Gαq/11 biased small molecule (MSq1) to develop thyroid progenitor cells. Mouse embryonic stem cells (mESCs) were differentiated into anterior endoderm cells and treated with either TSH or MSq1 in the presence or absence of PKC inhibitors. The transcriptional and translational response of key thyroid markers-sodium iodide symporter (NIS), thyroglobulin (TG), and thyrotropin receptor (TSHR) as well as potential signaling molecules-were then analyzed. The data confirmed that MSq1 is a potent Gαq/11 activator with a major increase in Gαq/11 signaling when compared to TSH. MSq1 activation resulted in an increase in thyroid-specific genes, demonstrating that enhanced PKC signaling was able to induce their expression. The specificity of the PKC signals over the protein kinase A (PKA) pathway in regulating thyroid gene expression was shown by using a specific PKC enzyme inhibitor. The data revealed that TG and NIS expression were suppressed in the presence of the PKC inhibition but, in contrast, were not influenced by PKA inhibition. This indicated that PKC activation was the dominant pathway in the inductive process for thyroid hormone production. Furthermore, by examining PKC isoforms we found that PKCξ was the predominant form in the ES cells that mediated the effects. Since PKCξ can lead to activation of transforming growth factor-β-activated kinase (pTAK1), and its downstream effector nuclear factor κB (NFκB) complex, this demonstrated the involvement of the TAK1/NFκB pathway in thyroid speciation.
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Affiliation(s)
- Rauf Latif
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- James J. Peters VA Medical Center, New York, NY 10468, USA
| | - Syed A Morshed
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- James J. Peters VA Medical Center, New York, NY 10468, USA
| | - Colin McCann
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Terry F Davies
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- James J. Peters VA Medical Center, New York, NY 10468, USA
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9
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Nakamura Y, Yoshihara A, Kiriya M, Kawashima A, Tanigawa K, Luo Y, Fujiwara Y, Maruyama K, Watanabe S, Kihara-Negishi F, Karasawa K, Suzuki K. Thyroid stimulating hormone suppresses the expression and activity of cytosolic sulfotransferase 1a1 in thyrocytes. Endocr J 2022; 69:1261-1269. [PMID: 35675983 DOI: 10.1507/endocrj.ej22-0055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Sulfonation is an important step in the metabolism of dopamine, estrogens, dehydroepiandrosterone, as well as thyroid hormones. However, the regulation of cytosolic sulfotransferases in the thyroid is not well understood. In a DNA microarray analysis of rat thyroid FRTL-5 cells, we found that the mRNA expression of 10 of 48 sulfotransferases was significantly altered by thyroid stimulating hormone (TSH), with that of sulfotransferase family 1A member 1 (SULT1A1) being the most significantly affected. Real-time PCR and Western blot analyses revealed that TSH, forskolin and dibutyryl cyclic AMP significantly suppressed SULT1A1 mRNA and protein levels in a time- and concentration-dependent manner. Moreover, immunofluorescence staining of FRTL-5 cells showed that SULT1A1 is localized in the perinuclear area in the absence of TSH but is spread throughout the cytoplasm with reduced fluorescence intensity in the presence of TSH. Sulfotransferase activity in FRTL-5 cells, measured using 3'-phosphoadenosine-5'-phosphosulfate as a donner and p-nitrophenol as an acceptor substrate, was significantly reduced by TSH. These findings suggest that the expression and activity of SULT1A1 are modulated by TSH in thyrocytes.
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Affiliation(s)
| | - Aya Yoshihara
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
- Center for Medical Education, Faculty of Medicine, Toho University, Tokyo 143-8540, Japan
| | - Mitsuo Kiriya
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | - Akira Kawashima
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | | | - Yuqian Luo
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital and Jiangsu Key Laboratory for Molecular Medicine, Nanjing University Medical School, Nanjing 210008, China
| | - Yoko Fujiwara
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | - Keiji Maruyama
- Faculty of Pharma-Science, Teikyo University, Tokyo 173-8605, Japan
| | | | | | - Ken Karasawa
- Faculty of Pharma-Science, Teikyo University, Tokyo 173-8605, Japan
| | - Koichi Suzuki
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
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10
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Krieger CC, Sui X, Kahaly GJ, Neumann S, Gershengorn MC. Inhibition of TSH/IGF-1 Receptor Crosstalk by Teprotumumab as a Treatment Modality of Thyroid Eye Disease. J Clin Endocrinol Metab 2022; 107:e1653-e1660. [PMID: 34788857 PMCID: PMC8947786 DOI: 10.1210/clinem/dgab824] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Indexed: 11/19/2022]
Abstract
CONTEXT We previously presented evidence that TSH receptor (TSHR)-stimulating autoantibodies (TSAbs) bind to and activate TSHRs but do not bind to IGF1 receptors (IGF1Rs). Nevertheless, we showed that IGF1Rs were involved in thyroid eye disease (TED) pathogenesis because TSAbs activated crosstalk between TSHR and IGF1R. Teprotumumab, originally generated to inhibit IGF1 binding to IGF1R, was recently approved for the treatment of TED (Tepezza). OBJECTIVE To investigate the role of TSHR/IGF1R crosstalk in teprotumumab treatment of TED. DESIGN We used orbital fibroblasts from patients with TED (TEDOFs) and measured stimulated hyaluronan (HA) secretion as a measure of orbital fibroblast activation by TED immunoglobulins (TED-Igs) and monoclonal TSAb M22. We previously showed that M22, which does not bind to IGF1R, stimulated HA in a biphasic dose-response with the higher potency phase dependent on TSHR/IGF1R crosstalk and the lower potency phase independent of IGF1R. Stimulation by TED-Igs and M22 was measured in the absence or presence of teprotumumab biosimilar (Tepro) or K1-70, an antibody that inhibits TSHR. RESULTS We show: (1) Tepro dose-dependently inhibits stimulation by TED-Igs; (2) Tepro does not bind to TSHRs; (3) Tepro inhibits IGF1R-dependent M22-induced HA production, which is mediated by TSHR/IGF1R crosstalk, but not IGF1R-independent M22 stimulation; and (4) β-arrestin 1 knockdown, which blocks TSHR/IGF1R crosstalk and prevents Tepro inhibition of HA production by M22 and by a pool of TED-Igs. CONCLUSION We conclude that Tepro inhibits HA production by TEDOFs by inhibiting TSHR/IGF1R crosstalk and suggest that inhibition of TSHR/IGF1R crosstalk is the mechanism of its action in treating TED.
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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, MD 20892, USA
| | - Xiangliang Sui
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - George J Kahaly
- Molecular Thyroid Research Laboratory, Department of Medicine I, Johannes Gutenberg University (JGU) Medical Center, Mainz 55131, Germany
| | - Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Marvin C Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
- Correspondence: Marvin C. Gershengorn, MD, Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 50 South Dr., Building 50, Room 4134, Bethesda, MD 20892, USA.
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11
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Jang D, Eliseeva E, Klubo-Gwiezdzinska J, Neumann S, Gershengorn MC. TSH stimulation of human thyroglobulin and thyroid peroxidase gene transcription is partially dependent on internalization. Cell Signal 2022; 90:110212. [PMID: 34896620 PMCID: PMC8725617 DOI: 10.1016/j.cellsig.2021.110212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 11/29/2021] [Accepted: 12/05/2021] [Indexed: 02/03/2023]
Abstract
The TSH receptor (TSHR) is the major regulator of thyroid hormone biosynthesis in human thyrocytes by regulating the transcription of a number of genes including thyroglobulin (TG) and thyroperoxidase (TPO). Until recently, it was thought that TSHR initiated signal transduction pathways only at the cell-surface and that internalization was primarily involved in TSHR desensitization and downregulation. Studies primarily in mouse cells showed that TSHR internalization regulates gene transcription at an intracellular site also. However, this has not been shown for genes involved in thyroid hormone biosynthesis in human thyrocytes. We used human thyrocytes in primary culture. In these cells, the dose-response to TSH for gene expression is biphasic with low doses upregulating gene expression and higher doses decreasing gene expression. We used two approaches to inhibit internalization. In the first, we used inhibitors of dynamins, dynasore and dyngo-4a. Pretreatment with dynasore or dyngo-4a markedly inhibited TSH upregulation of TG and TPO mRNAs, as well as TG secretion. In the second, we used knockdown of dynamin 2, which is the most abundant dynamin in human thyrocytes. We showed that dynamin 2 knockdown inhibited TSHR internalization and decreased the TSH-stimulated levels of TG and TPO mRNAs and proteins. Lastly, we showed that the level of the activatory transcription factor phosphorylated cAMP response element binding protein (pCREB) in the cell nuclei was reduced by 68% when internalization was inhibited. We conclude that upregulation of genes involved in thyroid hormone synthesis in human thyrocytes is, in part, dependent on internalization leading to nuclear localization of an activated transcription factor(s).
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Affiliation(s)
- Daesong Jang
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Elena Eliseeva
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Joanna Klubo-Gwiezdzinska
- Metabolic Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Marvin C. Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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12
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Jing L, Zhang Q. Intrathyroidal feedforward and feedback network regulating thyroid hormone synthesis and secretion. Front Endocrinol (Lausanne) 2022; 13:992883. [PMID: 36187113 PMCID: PMC9519864 DOI: 10.3389/fendo.2022.992883] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
Thyroid hormones (THs), including T4 and T3, are produced and released by the thyroid gland under the stimulation of thyroid-stimulating hormone (TSH). The homeostasis of THs is regulated via the coordination of the hypothalamic-pituitary-thyroid axis, plasma binding proteins, and local metabolism in tissues. TH synthesis and secretion in the thyrocytes-containing thyroid follicles are exquisitely regulated by an elaborate molecular network comprising enzymes, transporters, signal transduction machineries, and transcription factors. In this article, we synthesized the relevant literature, organized and dissected the complex intrathyroidal regulatory network into structures amenable to functional interpretation and systems-level modeling. Multiple intertwined feedforward and feedback motifs were identified and described, centering around the transcriptional and posttranslational regulations involved in TH synthesis and secretion, including those underpinning the Wolff-Chaikoff and Plummer effects and thyroglobulin-mediated feedback regulation. A more thorough characterization of the intrathyroidal network from a systems biology perspective, including its topology, constituent network motifs, and nonlinear quantitative properties, can help us to better understand and predict the thyroidal dynamics in response to physiological signals, therapeutic interventions, and environmental disruptions.
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Affiliation(s)
- Li Jing
- Department of Toxicology and Hygienic Chemistry, School of Public Health, Capital Medical University, Beijing, China
- *Correspondence: Li Jing, ; Qiang Zhang,
| | - Qiang Zhang
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
- *Correspondence: Li Jing, ; Qiang Zhang,
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13
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Krieger CC, Kahaly GJ, Azam A, Klubo-Gwiezdzinska J, Neumann S, Gershengorn MC. Graves' Autoantibodies Exhibit Different Stimulating Activities in Cultures of Thyrocytes and Orbital Fibroblasts Not Reflected by Clinical Assays. Thyroid 2022; 32:90-96. [PMID: 34714162 PMCID: PMC8792498 DOI: 10.1089/thy.2021.0326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Background: The pathogenesis of Graves' hyperthyroidism (GH) and associated Graves' orbitopathy (GO) appears to involve stimulatory autoantibodies (thyrotropin receptor [TSHR]-stimulating antibodies [TSAbs]) that bind to and activate TSHRs on thyrocytes and orbital fibroblasts. In general, measurement of circulating TSHR antibodies by clinical assays correlates with the status of GH and GO. However, most clinical measurements of TSHR antibodies use competitive binding assays that do not distinguish between TSAbs and antibodies that bind to but do not activate TSHRs. Moreover, clinical assays for TSAbs measure stimulation of only one signaling pathway, the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway, in engineered cells that are not thyrocytes or orbital fibroblasts. We determined whether measuring TSAbs by a cAMP-PKA readout in engineered cells accurately reveals the efficacies of stimulation by these antibodies on thyrocytes and orbital fibroblasts. Methods: We measured TSAb stimulation of normal human thyrocytes and orbital fibroblasts from patients with GO in primary cultures in vitro. In thyrocytes, we measured secretion of thyroglobulin (TG) and in orbital fibroblasts secretion of hyaluronan (hyaluronic acid [HA]). We also measured stimulation of cAMP production in engineered TSHR-expressing cells in an assay similar to clinical assays. Furthermore, we determined whether there were differences in stimulation of thyrocytes and orbital fibroblasts by TSAbs from patients with GH alone versus from patients with GO understanding that patients with GO have accompanying GH. Results: We found a positive correlation between TSAb stimulation of cAMP production in engineered cells and TG secretion by thyrocytes as well as HA secretion by orbital fibroblasts. However, TSAbs from GH patients stimulated thyrocytes more effectively than TSAbs from GO patients, whereas TSAbs from GO patients were more effective in activating orbital fibroblasts than TSAbs from GH patients. Conclusions: Clinical assays of stimulation by TSAbs measuring activation of the cAMP-PKA pathway do correlate with stimulation of thyrocytes and orbital fibroblasts; however, they do not distinguish between TSAbs from GH and GO patients. In vitro, TSAbs exhibit selectivity in activating TSHRs since TSAbs from GO patients were more effective in stimulating orbital fibroblasts and TSAbs from GH patients were more effective in stimulating thyrocytes.
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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, USA
| | - George J. Kahaly
- Molecular Thyroid Research Laboratory, Department of Medicine I, Johannes Gutenberg University (JGU) Medical Center, Mainz, Germany
| | - Asma Azam
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Joanna Klubo-Gwiezdzinska
- Metabolic Diseases Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Marvin C. Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
- Address correspondence to: Marvin C. Gershengorn, MD, Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Draman MS, Zhang L, Dayan C, Ludgate M. Orbital Signaling in Graves' Orbitopathy. Front Endocrinol (Lausanne) 2021; 12:739994. [PMID: 34899596 PMCID: PMC8660111 DOI: 10.3389/fendo.2021.739994] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/21/2021] [Indexed: 11/13/2022] Open
Abstract
Graves' orbitopathy (GO) is a complex and poorly understood disease in which extensive remodeling of orbital tissue is dominated by adipogenesis and hyaluronan production. The resulting proptosis is disfiguring and underpins the majority of GO signs and symptoms. While there is strong evidence for the thyrotropin receptor (TSHR) being a thyroid/orbit shared autoantigen, the insulin-like growth factor 1 receptor (IGF1R) is also likely to play a key role in the disease. The pathogenesis of GO has been investigated extensively in the last decade with further understanding of some aspects of the disease. This is mainly derived by using in vitro and ex vivo analysis of the orbital tissues. Here, we have summarized the features of GO pathogenesis involving target autoantigens and their signaling pathways.
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Affiliation(s)
- Mohd Shazli Draman
- Thyroid Research Group, Cardiff University School of Medicine, Cardiff, United Kingdom
- KPJ Healthcare University College, Nilai, Malaysia
| | - Lei Zhang
- Thyroid Research Group, Cardiff University School of Medicine, Cardiff, United Kingdom
| | - Colin Dayan
- Thyroid Research Group, Cardiff University School of Medicine, Cardiff, United Kingdom
| | - Marian Ludgate
- Thyroid Research Group, Cardiff University School of Medicine, Cardiff, United Kingdom
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15
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Feng F, Han H, Wu S, Wang H. Crosstalk Between Abnormal TSHR Signaling Activation and PTEN/PI3K in the Dedifferentiation of Thyroid Cancer Cells. Front Oncol 2021; 11:718578. [PMID: 34650915 PMCID: PMC8506026 DOI: 10.3389/fonc.2021.718578] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/08/2021] [Indexed: 11/29/2022] Open
Abstract
Iodide uptake and the metabolism of thyroid cells are regulated by thyrotropin (TSH)-TSH receptor (TSHR) signaling. Thus, it is necessary to elevate serum TSH levels by T4 withdraw or rTSH administration to facilitate radioiodide (131I) therapy for differentiated thyroid cancer (DTC). However, non-iodide-avid metastases of DTC which is dedifferentiated do not respond to stimulation by high levels of TSH, suggesting abnormal TSH-TSHR signal transduction in cancer cells. In addition, PI3K/AKT/mTOR signaling activation has been shown to be associated with the dedifferentiated phenotype of thyroid cancer, but the mechanism remains elusive. Therefore, in this study, we aimed to explore the role of abnormal TSH-TSHR signaling activation in regulating iodide uptake and cell mobility in thyroid cancer and its relationship with PI3K/AKT/mTOR signaling. We found that in thyroid cancer cells, TSH binds TSHR coupled to the Gα12/13 protein and then activates RhoA through interacting with leukemia associated RhoA guanine exchange factor (LARG). This results in a promigration tumorigenic phenotype independent of canonical TSHR-GαS signaling that regulates the expression of molecules involved in iodine uptake and metabolism. We observed that signaling pathways downstream of Gα12/13 signaling were increased, while that of Gαs signaling was decreased in thyroid cancer cells undergoing dedifferentiation compared to control cells following stimulation with different levels of TSH. PI3K/AKT/mTOR signaling activation enhanced Gα12/13 signaling through increasing LARG levels but also inhibited the expression of molecules downstream of Gαs signaling, including thyroid-specific molecules, and iodide uptake. In summary, our results demonstrate the noncanonical activation of TSH-TSHR signaling and its role in increasing the cell mobility and dedifferentiation of thyroid cancer through crosstalk with PI3K/AKT/mTOR signaling.
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Affiliation(s)
- Fang Feng
- Department of Nuclear Medicine, Xinhua Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Huiqin Han
- Shanghai Mental Health Center, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Shuqi Wu
- Department of Nuclear Medicine, Xinhua Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Hui Wang
- Department of Nuclear Medicine, Xinhua Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
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16
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Fusion with Promiscuous Gα 16 Subunit Reveals Signaling Bias at Muscarinic Receptors. Int J Mol Sci 2021; 22:ijms221810089. [PMID: 34576254 PMCID: PMC8469978 DOI: 10.3390/ijms221810089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/06/2021] [Accepted: 09/14/2021] [Indexed: 11/25/2022] Open
Abstract
A complex evaluation of agonist bias at G-protein coupled receptors at the level of G-protein classes and isoforms including non-preferential ones is essential for advanced agonist screening and drug development. Molecular crosstalk in downstream signaling and a lack of sufficiently sensitive and selective methods to study direct coupling with G-protein of interest complicates this analysis. We performed binding and functional analysis of 11 structurally different agonists on prepared fusion proteins of individual subtypes of muscarinic receptors and non-canonical promiscuous α-subunit of G16 protein to study agonist bias. We have demonstrated that fusion of muscarinic receptors with Gα16 limits access of other competitive Gα subunits to the receptor, and thus enables us to study activation of Gα16 mediated pathway more specifically. Our data demonstrated agonist-specific activation of G16 pathway among individual subtypes of muscarinic receptors and revealed signaling bias of oxotremorine towards Gα16 pathway at the M2 receptor and at the same time impaired Gα16 signaling of iperoxo at M5 receptors. Our data have shown that fusion proteins of muscarinic receptors with α-subunit of G-proteins can serve as a suitable tool for studying agonist bias, especially at non-preferential pathways.
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17
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Yang C, He Z, Zhang Q, Lu M, Zhao J, Chen W, Gao L. TSH Activates Macrophage Inflammation by G13- and G15-dependent Pathways. Endocrinology 2021; 162:6225351. [PMID: 33851697 DOI: 10.1210/endocr/bqab077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Indexed: 12/17/2022]
Abstract
Thyroid-stimulating hormone (TSH) treatment activates inhibitor of NF-κB/nuclear factor κB (IκB/NFκB) and extracellular signal-regulated kinase (ERK)-P38 in macrophages, but how these pathways are activated, and how they contribute to the proinflammatory effect of TSH on macrophages remain unknown. The TSH receptor (TSHR) is coupled to 4 subfamilies of G proteins (Gs, Gi/o, Gq/11, and G12/13) for its downstream signaling. This study investigated the G protein subtypes responsible for the proinflammatory effect of TSH on macrophages. qPCR showed that Gi2, Gi3, Gas, Gq, G11, G12, G13, and G15 are abundantly expressed by macrophages. The contribution of different G protein pathways to the proinflammatory effect was studied by the corresponding inhibitors or siRNA interference. While TSH-induced IκB phosphorylation was not inhibited by Gs inhibitor NF449, Gi inhibitor pertussis toxin, or Gq or G11 siRNA, it was blocked by phospholipase C inhibitor U73122 or G15 siRNA interference. TSH-induced ERK and P38 phosphorylation was blocked by G13 but not G12 siRNA interference. Interference of either G13 or G15 could block the proinflammatory effect of TSH on macrophages. The present study demonstrate that TSH activates macrophage inflammation by the G13/ERK-P38/Rho GTPase and G15/phospholipase C (PLC)/protein kinases C (PKCs)/IκB pathways.
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Affiliation(s)
- Chongbo Yang
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong First Medical University, Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Zhao He
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong First Medical University, Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Qunye Zhang
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Ministry of Public Health, the State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Ming Lu
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong First Medical University, Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Jiajun Zhao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong First Medical University, Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Wenbin Chen
- Scientific Center, Shandong Provincial Hospital affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Ling Gao
- Scientific Center, Shandong Provincial Hospital affiliated to Shandong First Medical University, Jinan, Shandong, China
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Prévide RM, Wang K, Smiljanic K, Janjic MM, Nunes MT, Stojilkovic SS. Expression and Role of Thyrotropin Receptors in Proopiomelanocortin-Producing Pituitary Cells. Thyroid 2021; 31:850-858. [PMID: 33191870 PMCID: PMC8110008 DOI: 10.1089/thy.2020.0222] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Background: Thyrotropin (TSH) is well known as the hormone of the anterior pituitary thyrotrophs responsible for acting in the thyroid gland, where it stimulates synthesis and release of thyroid hormones through Gs and Gq/11 protein coupled TSH receptors (TSHRs). Methods: In this study, we examined whether the functional TSHRs are also expressed in cultured rat pituitary cells, using double immunocytochemistry, quantitative reverse transcription-polymerase chain reaction analysis, cAMP and hormone measurements, and single-cell calcium imaging. Results: Double immunocytochemistry revealed the expression of TSHRs in cultured corticotrophs and melanotrophs, in addition to previously identified receptors in folliculostellate cells. The functional coupling of these receptors to the Gq/11 signaling pathway was not observed, as demonstrated by the lack of TSH activation of IP3-dependent calcium mobilization in these cells when bathed in calcium-deficient medium. However, TSH increased cAMP production in a time- and concentration-dependent manner and facilitated calcium influx in single corticotrophs and melanotrophs, indicating their coupling to the Gs signaling pathway. Consistent with these findings, TSH stimulated adrenocorticotropin and β-endorphin release in male and female pituitary cells in a time- and concentration-dependent manner without affecting the expression of proopiomelanocortin gene. Conclusions: These results indicate that TSH is a potential paracrine modulator of anterior pituitary corticotrophs and melanotrophs, controlling the exocytotic but not the transcriptional pathway in a cAMP/calcium influx-dependent manner.
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Affiliation(s)
- Rafael Maso Prévide
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
- CAPES Foundation, Ministry of Education of Brazil, Brasília, Brazil
- Address correspondence to: Rafael Maso Prévide, PhD, Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bldg. 10, Room 8N240, 10 Center Drive, Bethesda, MD 20892-1829, USA
| | - Kai Wang
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Kosara Smiljanic
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Marija M. Janjic
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Maria Tereza Nunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Stanko S. Stojilkovic
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Yang LK, Hou ZS, Tao YX. Biased signaling in naturally occurring mutations of G protein-coupled receptors associated with diverse human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:165973. [PMID: 32949766 PMCID: PMC7722056 DOI: 10.1016/j.bbadis.2020.165973] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) play critical roles in transmitting a variety of extracellular signals into the cells and regulate diverse physiological functions. Naturally occurring mutations that result in dysfunctions of GPCRs have been known as the causes of numerous diseases. Significant progresses have been made in elucidating the pathophysiology of diseases caused by mutations. The multiple intracellular signaling pathways, such as G protein-dependent and β-arrestin-dependent signaling, in conjunction with recent advances on biased agonism, have broadened the view on the molecular mechanism of disease pathogenesis. This review aims to briefly discuss biased agonism of GPCRs (biased ligands and biased receptors), summarize the naturally occurring GPCR mutations that cause biased signaling, and propose the potential pathophysiological relevance of biased mutant GPCRs associated with various endocrine diseases.
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Affiliation(s)
- Li-Kun Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Zhi-Shuai Hou
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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20
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Krause G, Eckstein A, Schülein R. Modulating TSH Receptor Signaling for Therapeutic Benefit. Eur Thyroid J 2020; 9:66-77. [PMID: 33511087 PMCID: PMC7802447 DOI: 10.1159/000511871] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/01/2020] [Indexed: 12/14/2022] Open
Abstract
Autoimmune thyroid-stimulating antibodies are activating the thyrotropin receptor (TSHR) in both the thyroid and the eye, but different molecular mechanisms are induced in both organs, leading to Graves' disease (GD) and Graves' orbitopathy (GO), respectively. Therapy with anti-thyroid drugs to reduce hyperthyroidism (GD) by suppressing the biosynthesis of thyroid hormones has only an indirect effect on GO, since it does not causally address pathogenic TSHR activation itself. GO is thus very difficult to treat. The activated TSHR but also the cross-interacting insulin-like growth factor 1 receptor (IGF-1R) contribute to this issue. The TSHR is a heptahelical G-protein-coupled receptor, whereas the IGF-1R is a receptor tyrosine kinase. Despite these fundamental structural differences, both receptors are phosphorylated by G-protein receptor kinases, which enables β-arrestin binding. Arrestins mediate receptor internalization and also activate the mitogen-activated protein kinase pathway. Moreover, emerging results suggest that arrestin plays a critical role in the cross-interaction of the TSHR and the IGF-1R either in their common signaling pathway and/or during an indirect or potential TSHR/IGF-1R interaction. In this review, novel pharmacological strategies with allosteric small-molecule modulators to treat GO and GD on the level of the TSHR and/or the TSHR/IGF-1R cross-interaction will be discussed. Moreover, monoclonal antibody approaches targeting the TSHR or the IGF-1R and thereby preventing activation of either receptor will be presented. Another chapter addresses the immunomodulation to treat GO using TSHR-derived peptides targeting the human leukocyte antigen DR isotope (HLA-DR), which is a feasible approach to tackle GO, since HLA-DR and TSHR are overexpressed in orbital tissues of GO patients.
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Affiliation(s)
- Gerd Krause
- Structural Biology, Leibniz-Forschungsinstitut für molekulare Pharmakologie (FMP), Berlin, Germany
| | - Anja Eckstein
- Department of Ophthalmology, University Hospital Essen, Essen, Germany
| | - Ralf Schülein
- Protein Trafficking, Leibniz-Forschungsinstitut für molekulare Pharmakologie (FMP), Berlin, Germany
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21
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Schöneberg T, Liebscher I. Mutations in G Protein-Coupled Receptors: Mechanisms, Pathophysiology and Potential Therapeutic Approaches. Pharmacol Rev 2020; 73:89-119. [PMID: 33219147 DOI: 10.1124/pharmrev.120.000011] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
There are approximately 800 annotated G protein-coupled receptor (GPCR) genes, making these membrane receptors members of the most abundant gene family in the human genome. Besides being involved in manifold physiologic functions and serving as important pharmacotherapeutic targets, mutations in 55 GPCR genes cause about 66 inherited monogenic diseases in humans. Alterations of nine GPCR genes are causatively involved in inherited digenic diseases. In addition to classic gain- and loss-of-function variants, other aspects, such as biased signaling, trans-signaling, ectopic expression, allele variants of GPCRs, pseudogenes, gene fusion, and gene dosage, contribute to the repertoire of GPCR dysfunctions. However, the spectrum of alterations and GPCR involvement is probably much larger because an additional 91 GPCR genes contain homozygous or hemizygous loss-of-function mutations in human individuals with currently unidentified phenotypes. This review highlights the complexity of genomic alteration of GPCR genes as well as their functional consequences and discusses derived therapeutic approaches. SIGNIFICANCE STATEMENT: With the advent of new transgenic and sequencing technologies, the number of monogenic diseases related to G protein-coupled receptor (GPCR) mutants has significantly increased, and our understanding of the functional impact of certain kinds of mutations has substantially improved. Besides the classical gain- and loss-of-function alterations, additional aspects, such as biased signaling, trans-signaling, ectopic expression, allele variants of GPCRs, uniparental disomy, pseudogenes, gene fusion, and gene dosage, need to be elaborated in light of GPCR dysfunctions and possible therapeutic strategies.
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Affiliation(s)
- Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, Leipzig, Germany
| | - Ines Liebscher
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, Leipzig, Germany
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22
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Kaur S, Auger C, Jeschke MG. Adipose Tissue Metabolic Function and Dysfunction: Impact of Burn Injury. Front Cell Dev Biol 2020; 8:599576. [PMID: 33251224 PMCID: PMC7676399 DOI: 10.3389/fcell.2020.599576] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 09/30/2020] [Indexed: 12/11/2022] Open
Abstract
For decades, adipose tissue had been considered as merely a storage depot and cushion to protect organs against trauma and injury. However, in recent years, a number of impactful studies have pinpointed the adipose tissue as an endocrine organ mediating systemic dysfunction in not only metabolic disorders such as obesity, but also in the stages following traumatic events such as severe burns. For instance, thermal injury induces a chronic β-adrenergic response associated with drastic increases in adipose lipolysis, macrophage infiltration and IL-6 mediated browning of white adipose tissue (WAT). The downstream consequences of these physiological changes to adipose, such as hepatomegaly and muscle wasting, are only now coming to light and suggest that WAT is both a culprit in and initiator of metabolic disorders after burn injury. To that effect, the aim of this review is to chronicle and critically analyze the scientific advances made in the study of adipose tissue with regards to its role in orchestrating the hypermetabolic response and detrimental effects of burn injury. The topics covered include the magnitude of the lipolytic response following thermal trauma and how WAT browning and inflammation perpetuate this cycle as well as how WAT physiology impacts insulin resistance and hyperglycemia post-burn. To conclude, we discuss how these findings can be translated from bench to bedside in the form of therapeutic interventions which target physiological changes to WAT to restore systemic homeostasis following a severe burn.
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Affiliation(s)
- Supreet Kaur
- Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Departments of Surgery and Immunology, University of Toronto, Toronto, ON, Canada
| | - Christopher Auger
- Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Departments of Surgery and Immunology, University of Toronto, Toronto, ON, Canada
| | - Marc G Jeschke
- Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Departments of Surgery and Immunology, University of Toronto, Toronto, ON, Canada
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23
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The Molecular Function and Clinical Role of Thyroid Stimulating Hormone Receptor in Cancer Cells. Cells 2020; 9:cells9071730. [PMID: 32698392 PMCID: PMC7407617 DOI: 10.3390/cells9071730] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 01/18/2023] Open
Abstract
The thyroid stimulating hormone (TSH) and its cognate receptor (TSHR) are of crucial importance for thyrocytes to proliferate and exert their functions. Although TSHR is predominantly expressed in thyrocytes, several studies have revealed that functional TSHR can also be detected in many extra-thyroid tissues, such as primary ovarian and hepatic tissues as well as their corresponding malignancies. Recent advances in cancer biology further raise the possibility of utilizing TSH and/or TSHR as a therapeutic target or as an informative index to predict treatment responses in cancer patients. The TSH/TSHR cascade has been considered a pivotal modulator for carcinogenesis and/or tumor progression in these cancers. TSHR belongs to a sub-group of family A G-protein-coupled receptors (GPCRs), which activate a bundle of well-defined signaling transduction pathways to enhance cell renewal in response to external stimuli. In this review, recent findings regarding the molecular basis of TSH/TSHR functions in either thyroid or extra-thyroid tissues and the potential of directly targeting TSHR as an anticancer strategy are summarized and discussed.
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Schulze A, Kleinau G, Neumann S, Scheerer P, Schöneberg T, Brüser A. The intramolecular agonist is obligate for activation of glycoprotein hormone receptors. FASEB J 2020; 34:11243-11256. [PMID: 32648604 DOI: 10.1096/fj.202000100r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 01/15/2023]
Abstract
In contrast to most rhodopsin-like G protein-coupled receptors, the glycoprotein hormone receptors (GPHR) have a large extracellular N-terminus for hormone binding. The hormones do not directly activate the transmembrane domain but mediate their action via a, thus, far only partially known Tethered Agonistic LIgand (TALI). The existence of such an intramolecular agonist was initially indicated by site-directed mutation studies and activating peptides derived from the extracellular hinge region. It is still unknown precisely how TALI is involved in intramolecular signal transmission. We combined systematic mutagenesis studies at the luteinizing hormone receptor and the thyroid-stimulating hormone receptor (TSHR), stimulation with a drug-like agonist (E2) of the TSHR, and structural homology modeling to unravel the functional and structural properties defining the TALI region. Here, we report that TALI (a) is predisposed to constitutively activate GPHR, (b) can by itself rearrange GPHR into a fully active conformation, (c) stabilizes active GPHR conformation, and (d) is not involved in activation of the TSHR by E2. In the active state conformation, TALI forms specific interactions between the N-terminus and the transmembrane domain. We show that stabilization of an active state is dependent on TALI, including activation by hormones and constitutively activating mutations.
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Affiliation(s)
- Annelie Schulze
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Gunnar Kleinau
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Patrick Scheerer
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Antje Brüser
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
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Boutin A, Krieger CC, Marcus-Samuels B, Klubo-Gwiezdzinska J, Neumann S, Gershengorn MC. TSH Receptor Homodimerization in Regulation of cAMP Production in Human Thyrocytes in vitro. Front Endocrinol (Lausanne) 2020; 11:276. [PMID: 32425890 PMCID: PMC7203478 DOI: 10.3389/fendo.2020.00276] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 04/14/2020] [Indexed: 01/30/2023] Open
Abstract
Thyrotropin hormone (TSH) was reported to exhibit biphasic regulation of cAMP production in human thyroid slices; specifically, upregulation at low TSH doses transitioning to inhibition at high doses. We observed this phenomenon in HEK293 cells overexpressing TSH receptors (TSHRs) but in only 25% of human thyrocytes (hThyros) in vitro. Because TSHR expression in hThyros in vitro was low, we tested the hypothesis that high, in situ levels of TSHRs were needed for biphasic cAMP regulation. We increased expression of TSHRs by infecting hThyros with adenoviruses expressing human TSHR (AdhTSHR), measured TSH-stimulated cAMP production and TSHR homodimerization. TSHR mRNA levels in hThyros in vitro were 100-fold lower than in human thyroid tissue. AdhTSHR infection increased TSHR mRNA expression to levels found in thyroid tissue and flow cytometry showed that cell-surface TSHRs increased more than 15-fold. Most uninfected hThyro preparations exhibited monotonic cAMP production. In contrast, most hThyro preparations infected with AdhTSHR expressing TSHR at in vivo levels exhibited biphasic TSH dose responses. Treatment of AdhTSHR-infected hThyros with pertussis toxin resulted in monotonic dose response curves demonstrating that lower levels of cAMP production at high TSH doses were mediated by Gi/Go proteins. Proximity ligation assays confirmed that AdhTSHR infection markedly increased the number of TSHR homodimers. We conclude that in situ levels of TSHRs as homodimers are needed for hThyros to exhibit biphasic TSH regulation of cAMP production.
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Affiliation(s)
- Alisa Boutin
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health Bethesda, MD, United States
| | - Christine C. Krieger
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health Bethesda, MD, United States
| | - Bernice Marcus-Samuels
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health Bethesda, MD, United States
| | - Joanna Klubo-Gwiezdzinska
- Metabolic Disease Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health Bethesda, MD, United States
| | - Marvin C. Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health Bethesda, MD, United States
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Jakubik J, El-Fakahany EE. Current Advances in Allosteric Modulation of Muscarinic Receptors. Biomolecules 2020; 10:biom10020325. [PMID: 32085536 PMCID: PMC7072599 DOI: 10.3390/biom10020325] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 02/07/2023] Open
Abstract
Allosteric modulators are ligands that bind to a site on the receptor that is spatially separated from the orthosteric binding site for the endogenous neurotransmitter. Allosteric modulators modulate the binding affinity, potency, and efficacy of orthosteric ligands. Muscarinic acetylcholine receptors are prototypical allosterically-modulated G-protein-coupled receptors. They are a potential therapeutic target for the treatment of psychiatric, neurologic, and internal diseases like schizophrenia, Alzheimer’s disease, Huntington disease, type 2 diabetes, or chronic pulmonary obstruction. Here, we reviewed the progress made during the last decade in our understanding of their mechanisms of binding, allosteric modulation, and in vivo actions in order to understand the translational impact of studying this important class of pharmacological agents. We overviewed newly developed allosteric modulators of muscarinic receptors as well as new spin-off ideas like bitopic ligands combining allosteric and orthosteric moieties and photo-switchable ligands based on bitopic agents.
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Affiliation(s)
- Jan Jakubik
- Department of Neurochemistry, Institute of Physiology CAS, 142 20 Prague, Czech Republic
- Correspondence: (J.J.); (E.E.E.-F.)
| | - Esam E. El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN 55455, USA
- Correspondence: (J.J.); (E.E.E.-F.)
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Randáková A, Nelic D, Ungerová D, Nwokoye P, Su Q, Doležal V, El-Fakahany EE, Boulos J, Jakubík J. Novel M 2 -selective, G i -biased agonists of muscarinic acetylcholine receptors. Br J Pharmacol 2020; 177:2073-2089. [PMID: 31910288 DOI: 10.1111/bph.14970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE More than 30% of currently marketed medications act via GPCRs. Thus, GPCRs represent one of the most important pharmacotherapeutic targets. In contrast to traditional agonists activating multiple signalling pathways, agonists activating a single signalling pathway represent a new generation of drugs with increased specificity and fewer adverse effects. EXPERIMENTAL APPROACH We have synthesized novel agonists of muscarinic ACh receptors and tested their binding and function (on levels of cAMP and inositol phosphates) in CHO cells expressing individual subtypes of muscarinic receptors, primary cultures of rat aortic smooth muscle cells and suspensions of digested native tissues from rats. Binding of the novel compounds to M2 receptors was modelled in silico. KEY RESULTS Two of the tested new compounds (1-(thiophen-2-ylmethyl)-3,6-dihydro-2H-pyridinium and 1-methyl-1-(thiophen-2-ylmethyl)-3,6-dihydro-2H-pyridinium) only inhibited cAMP synthesis in CHO cells, primary cultures, and native tissues, with selectivity for M2 muscarinic receptors and displaying bias towards the Gi signalling pathway at all subtypes of muscarinic receptors. Molecular modelling revealed interactions with the orthosteric binding site in a way specific for a given agonist followed by agonist-specific changes in the conformation of the receptor. CONCLUSIONS AND IMPLICATIONS The identified compounds may serve as lead structures in the search for novel non-steroidal and non-opioid analgesics acting via M2 and M4 muscarinic receptors with reduced side effects associated with activation of the phospholipase C signalling pathway.
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Affiliation(s)
- Alena Randáková
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Dominik Nelic
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Dana Ungerová
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Peter Nwokoye
- Department of Physical Sciences, Barry University, Miami Shores, Florida
| | - Qiwen Su
- Department of Physical Sciences, Barry University, Miami Shores, Florida
| | - Vladimír Doležal
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Esam E El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, Minnesota
| | - John Boulos
- Department of Physical Sciences, Barry University, Miami Shores, Florida
| | - Jan Jakubík
- Department of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
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Latif R, Morshed SA, Ma R, Tokat B, Mezei M, Davies TF. A Gq Biased Small Molecule Active at the TSH Receptor. Front Endocrinol (Lausanne) 2020; 11:372. [PMID: 32676053 PMCID: PMC7333667 DOI: 10.3389/fendo.2020.00372] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/11/2020] [Indexed: 11/13/2022] Open
Abstract
G protein coupled receptors (GPCRs) can lead to G protein and non-G protein initiated signals. By virtue of its structural property, the TSH receptor (TSHR) has a unique ability to engage different G proteins making it highly amenable to selective signaling. In this study, we describe the identification and characterization of a novel small molecule agonist to the TSHR which induces primary engagement with Gαq/11. To identify allosteric modulators inducing selective signaling of the TSHR we used a transcriptional-based luciferase assay system with CHO-TSHR cells stably expressing response elements (CRE, NFAT, SRF, or SRE) that were capable of measuring signals emanating from the coupling of Gαs , Gαq/11, Gβγ, and Gα12/13, respectively. Using this system, TSH activated Gαs , Gαq/11, and Gα12/13 but not Gβγ. On screening a library of 50K molecules at 0.1,1.0 and 10 μM, we identified a novel Gq/11 agonist (named MSq1) which activated Gq/11 mediated NFAT-luciferase >4 fold above baseline and had an EC50= 8.3 × 10-9 M with only minor induction of Gαs and cAMP. Furthermore, MSq1 is chemically and structurally distinct from any of the previously reported TSHR agonist molecules. Docking studies using a TSHR transmembrane domain (TMD) model indicated that MSq1 had contact points on helices H1, H2, H3, and H7 in the hydrophobic pocket of the TMD and also with the extracellular loops. On co-treatment with TSH, MSq1 suppressed TSH-induced proliferation of thyrocytes in a dose-dependent manner but lacked the intrinsic ability to influence basal thyrocyte proliferation. This unexpected inhibitory property of MSq1 could be blocked in the presence of a PKC inhibitor resulting in derepressing TSH induced protein kinase A (PKA) signals and resulting in the induction of proliferation. Thus, the inhibitory effect of MSq1 on proliferation resided in its capacity to overtly activate protein kinase C (PKC) which in turn suppressed the proliferative signal induced by activation of the predomiant cAMP-PKA pathway of the TSHR. Treatment of rat thyroid cells (FRTL5) with MSq1 did not show any upregulation of gene expression of the key thyroid specific markers such as thyroglobulin(Tg), thyroid peroxidase (Tpo), sodium iodide symporter (Nis), and the TSH receptor (Tshr) further suggesting lack of involvement of MSq1 and Gαq/11 activation with cellular differentation. In summary, we identified and characterized a novel Gαq/11 agonist molecule acting at the TSHR and which showed a marked anti-proliferative ability. Hence, Gq biased activation of the TSHR is capable of ameliorating the proliferative signals from its orthosteric ligand and may offer a therapeutic option for thyroid growth modulation.
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Affiliation(s)
- Rauf Latif
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- James J. Peters VA Medical Center, New York, NY, United States
- *Correspondence: Rauf Latif
| | - Syed A. Morshed
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- James J. Peters VA Medical Center, New York, NY, United States
| | - Risheng Ma
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- James J. Peters VA Medical Center, New York, NY, United States
| | - Bengu Tokat
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Mihaly Mezei
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Terry F. Davies
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- James J. Peters VA Medical Center, New York, NY, United States
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Boutin A, Gershengorn MC, Neumann S. β-Arrestin 1 in Thyrotropin Receptor Signaling in Bone: Studies in Osteoblast-Like Cells. Front Endocrinol (Lausanne) 2020; 11:312. [PMID: 32508750 PMCID: PMC7251030 DOI: 10.3389/fendo.2020.00312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/24/2020] [Indexed: 12/20/2022] Open
Abstract
A direct action of thyrotropin (TSH, thyroid-stimulating hormone) on bone precursors in humans is controversial. Studies in rodent models have provided conflicting findings. We used cells derived from a moderately differentiated osteosarcoma stably overexpressing human TSH receptors (TSHRs) as a model of osteoblast precursors (U2OS-TSHR cells) to investigate TSHR-mediated effects in bone differentiation in human cells. We review our findings that (1) TSHR couples to several different G proteins to induce upregulation of genes associated with osteoblast activity-interleukin 11 (IL-11), osteopontin (OPN), and alkaline phosphatase (ALPL) and that the kinetics of the induction and the G protein-mediated signaling pathways involved were different for these genes; (2) TSH can stimulate β-arrestin-mediated signal transduction and that β-arrestin 1 in part mediates TSH-induced pre-osteoblast differentiation; and (3) TSHR/insulin-like growth factor 1 (IGF1) receptor (IGF1R) synergistically increased OPN secretion by TSH and IGF1 and that this crosstalk was mediated by physical association of these receptors in a signaling complex that uses β-arrestin 1 as a scaffold. These findings were complemented using a novel β-arrestin 1-biased agonist of TSHR. We conclude that TSHR can signal via several transduction pathways leading to differentiation of this model system of human pre-osteoblast cells and, therefore, that TSH can directly regulate these bone cells.
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30
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Neumann S, Malik SS, Marcus-Samuels B, Eliseeva E, Jang D, Klubo-Gwiezdzinska J, Krieger CC, Gershengorn MC. Thyrotropin Causes Dose-dependent Biphasic Regulation of cAMP Production Mediated by G s and G i/o Proteins. Mol Pharmacol 2020; 97:2-8. [PMID: 31704717 PMCID: PMC6864415 DOI: 10.1124/mol.119.117382] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
The thyrotropin (TSH) receptor (TSHR) signals via G proteins of all four classes and β-arrestin 1. Stimulation of TSHR leads to increasing cAMP production that has been reported as a monotonic dose-response curve that plateaus at high TSH doses. In HEK 293 cells overexpressing TSHRs (HEK-TSHR cells), we found that TSHR activation exhibits an "inverted U-shaped dose-response curve" with increasing cAMP production at low doses of TSH and decreased cAMP production at high doses (>1 mU/ml). Since protein kinase A inhibition by H-89 and knockdown of β-arrestin 1 or β-arrestin 2 did not affect the decreased cAMP production at high TSH doses, we studied the roles of TSHR downregulation and of Gi/Go proteins. A high TSH dose (100 mU/ml) caused a 33% decrease in cell-surface TSHR. However, because inhibiting TSHR downregulation with combined expression of a dominant negative dynamin 1 and β-arrestin 2 knockdown had no effect, we concluded that downregulation is not involved in the biphasic cAMP response. Pertussis toxin, which inhibits activation of Gi/Go, abolished the biphasic response with no statistically significant difference in cAMP levels at 1 and 100 mU/ml TSH. Concordantly, co-knockdown of Gi/Go proteins increased cAMP levels stimulated by 100 mU/ml TSH from 55% to 73% of the peak level. These data show that biphasic regulation of cAMP production is mediated by Gs and Gi/Go at low and high TSH doses, respectively, which may represent a mechanism to prevent overstimulation in TSHR-expressing cells. SIGNIFICANCE STATEMENT: We demonstrate biphasic regulation of TSH-mediated cAMP production involving coupling of the TSH receptor (TSHR) to Gs at low TSH doses and to Gi/o at high TSH doses. We suggest that this biphasic cAMP response allows the TSHR to mediate responses at lower levels of TSH and that decreased cAMP production at high doses may represent a mechanism to prevent overstimulation of TSHR-expressing cells. This mechanism could prevent chronic stimulation of thyroid gland function.
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Affiliation(s)
- Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Sarah S Malik
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Bernice Marcus-Samuels
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Elena Eliseeva
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Daesong Jang
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Joanna Klubo-Gwiezdzinska
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Christine C Krieger
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Marvin C Gershengorn
- Laboratory of Endocrinology and Receptor Biology (S.N., S.S.M., B.M.-S., E.E., D.J., C.C.K., M.C.G.) and Metabolic Disease Branch (J.K.-G.), National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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31
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Li J, Ge Y, Huang JX, Strømgaard K, Zhang X, Xiong XF. Heterotrimeric G Proteins as Therapeutic Targets in Drug Discovery. J Med Chem 2019; 63:5013-5030. [PMID: 31841625 DOI: 10.1021/acs.jmedchem.9b01452] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heterotrimeric G proteins are molecular switches in GPCR signaling pathways and regulate a plethora of physiological and pathological processes. GPCRs are efficient drug targets, and more than 30% of the drugs in use target them. However, selectively targeting an individual GPCR may be undesirable in various multifactorial diseases in which multiple receptors are involved. In addition, abnormal activation or expression of G proteins is frequently associated with diseases. Furthermore, G proteins harboring mutations often result in malignant diseases. Thus, targeting G proteins instead of GPCRs might provide alternative approaches for combating these diseases. In this review, we discuss the biochemistry of heterotrimeric G proteins, describe the G protein-associated diseases, and summarize the currently known modulators that can regulate the activities of G proteins. The outlook for targeting G proteins to treat diverse diseases is also included in this manuscript.
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Affiliation(s)
- Jian Li
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Yang Ge
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Jun-Xiang Huang
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Kristian Strømgaard
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Xiaolei Zhang
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Xiao-Feng Xiong
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
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The Pathogenic TSH β-subunit Variant C105Vfs114X Causes a Modified Signaling Profile at TSHR. Int J Mol Sci 2019; 20:ijms20225564. [PMID: 31703413 PMCID: PMC6888357 DOI: 10.3390/ijms20225564] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 11/01/2019] [Accepted: 11/03/2019] [Indexed: 01/05/2023] Open
Abstract
1) Background: Central congenital hypothyroidism (CCH) is a rare endocrine disorder that can be caused by mutations in the β-subunit of thyrotropin (TSHB). The TSHB mutation C105Vfs114X leads to isolated thyroid-stimulating-hormone-(TSH)-deficiency and results in a severe phenotype. The aim of this study was to gain more insight into the underlying molecular mechanism and the functional effects of this mutation based on two assumptions: a) the three-dimensional (3D) structure of TSH should be modified with the C105V substitution, and/or b) whether the C-terminal modifications lead to signaling differences. 2) Methods: wild-type (WT) and different mutants of hTSH were generated in human embryonic kidney 293 cells (HEK293 cells) and TSH preparations were used to stimulate thyrotropin receptor (TSHR) stably transfected into follicular thyroid cancer cells (FTC133-TSHR cells) and transiently transfected into HEK293 cells. Functional characterization was performed by determination of Gs, mitogen activated protein kinase (MAPK) and Gq/11 activation. 3) Results: The patient mutation C105Vfs114X and further designed TSH mutants diminished cyclic adenosine monophosphate (cAMP) signaling activity. Surprisingly, MAPK signaling for all mutants was comparable to WT, while none of the mutants induced PLC activation. 4) Conclusion: We characterized the patient mutation C105Vfs114X concerning different signaling pathways. We identified a strong decrease of cAMP signaling induction and speculate that this could, in combination with diverse signaling regarding the other pathways, accounting for the patient's severe phenotype.
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Colom M, Vidal B, Zimmer L. Is There a Role for GPCR Agonist Radiotracers in PET Neuroimaging? Front Mol Neurosci 2019; 12:255. [PMID: 31680859 PMCID: PMC6813225 DOI: 10.3389/fnmol.2019.00255] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/02/2019] [Indexed: 12/30/2022] Open
Abstract
Positron emission tomography (PET) is a molecular imaging modality that enables in vivo exploration of metabolic processes and especially the pharmacology of neuroreceptors. G protein-coupled receptors (GPCRs) play an important role in numerous pathophysiologic disorders of the central nervous system. Thus, they are targets of choice in PET imaging to bring proof concept of change in density in pathological conditions or in pharmacological challenge. At present, most radiotracers are antagonist ligands. In vitro data suggest that properties differ between GPCR agonists and antagonists: antagonists bind to receptors with a single affinity, whereas agonists are characterized by two different affinities: high affinity for receptors that undergo functional coupling to G-proteins, and low affinity for those that are not coupled. In this context, agonist radiotracers may be useful tools to give functional images of GPCRs in the brain, with high sensitivity to neurotransmitter release. Here, we review all existing PET radiotracers used from animals to humans and their role for understanding the ligand-receptor paradigm of GPCR in comparison with corresponding antagonist radiotracers.
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Affiliation(s)
- Matthieu Colom
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France.,CERMEP, Hospices Civils de Lyon, Bron, France
| | - Benjamin Vidal
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France
| | - Luc Zimmer
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France.,CERMEP, Hospices Civils de Lyon, Bron, France.,Institut National des Sciences et Techniques Nucléaires, CEA Saclay, Gif-sur-Yvette, France
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Abstract
In humans, the thyroid hormones T3 and T4 are synthesized in the thyroid gland in a process that crucially involves the iodoglycoprotein thyroglobulin. The overall structure of thyroglobulin is conserved in all vertebrates. Upon thyroglobulin delivery from thyrocytes to the follicular lumen of the thyroid gland via the secretory pathway, multiple tyrosine residues can become iodinated to form mono-iodotyrosine (MIT) and/or di-iodotyrosine (DIT); however, selective tyrosine residues lead to preferential formation of T4 and T3 at distinct sites. T4 formation involves oxidative coupling between two DIT side chains, and de novo T3 formation involves coupling between an MIT donor and a DIT acceptor. Thyroid hormone synthesis is stimulated by TSH activating its receptor (TSHR), which upregulates the activity of many thyroid gene products involved in hormonogenesis. Additionally, TSH regulates post-translational changes in thyroglobulin that selectively enhance its capacity for T3 formation - this process is important in iodide deficiency and in Graves disease. 167 different mutations, many of which are newly discovered, are now known to exist in TG (encoding human thyroglobulin) that can lead to defective thyroid hormone synthesis, resulting in congenital hypothyroidism.
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Affiliation(s)
- Cintia E Citterio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología/Cátedra de Genética, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Héctor M Targovnik
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología/Cátedra de Genética, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA.
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Seyedabadi M, Ghahremani MH, Albert PR. Biased signaling of G protein coupled receptors (GPCRs): Molecular determinants of GPCR/transducer selectivity and therapeutic potential. Pharmacol Ther 2019; 200:148-178. [PMID: 31075355 DOI: 10.1016/j.pharmthera.2019.05.006] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/26/2019] [Indexed: 02/07/2023]
Abstract
G protein coupled receptors (GPCRs) convey signals across membranes via interaction with G proteins. Originally, an individual GPCR was thought to signal through one G protein family, comprising cognate G proteins that mediate canonical receptor signaling. However, several deviations from canonical signaling pathways for GPCRs have been described. It is now clear that GPCRs can engage with multiple G proteins and the line between cognate and non-cognate signaling is increasingly blurred. Furthermore, GPCRs couple to non-G protein transducers, including β-arrestins or other scaffold proteins, to initiate additional signaling cascades. Receptor/transducer selectivity is dictated by agonist-induced receptor conformations as well as by collateral factors. In particular, ligands stabilize distinct receptor conformations to preferentially activate certain pathways, designated 'biased signaling'. In this regard, receptor sequence alignment and mutagenesis have helped to identify key receptor domains for receptor/transducer specificity. Furthermore, molecular structures of GPCRs bound to different ligands or transducers have provided detailed insights into mechanisms of coupling selectivity. However, receptor dimerization, compartmentalization, and trafficking, receptor-transducer-effector stoichiometry, and ligand residence and exposure times can each affect GPCR coupling. Extrinsic factors including cell type or assay conditions can also influence receptor signaling. Understanding these factors may lead to the development of improved biased ligands with the potential to enhance therapeutic benefit, while minimizing adverse effects. In this review, evidence for ligand-specific GPCR signaling toward different transducers or pathways is elaborated. Furthermore, molecular determinants of biased signaling toward these pathways and relevant examples of the potential clinical benefits and pitfalls of biased ligands are discussed.
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Affiliation(s)
- Mohammad Seyedabadi
- Department of Pharmacology, School of Medicine, Bushehr University of Medical Sciences, Iran; Education Development Center, Bushehr University of Medical Sciences, Iran
| | | | - Paul R Albert
- Ottawa Hospital Research Institute, Neuroscience, University of Ottawa, Canada.
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Shpakov AO. Molecular Mechanisms of the Relationship between Thyroid Dysfunctions and Diabetes Mellitus. J EVOL BIOCHEM PHYS+ 2018. [DOI: 10.1134/s0022093018040014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Löf C, Patyra K, Kero A, Kero J. Genetically modified mouse models to investigate thyroid development, function and growth. Best Pract Res Clin Endocrinol Metab 2018; 32:241-256. [PMID: 29779579 DOI: 10.1016/j.beem.2018.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The thyroid gland produces thyroid hormones (TH), which are essential regulators for growth, development and metabolism. The thyroid is mainly controlled by the thyroid-stimulating hormone (TSH) that binds to its receptor (TSHR) on thyrocytes and mediates its action via different G protein-mediated signaling pathways. TSH primarily activates the Gs-pathway, and at higher concentrations also the Gq/11-pathway, leading to an increase of intracellular cAMP and Ca2+, respectively. To date, the physiological importance of other G protein-mediated signaling pathways in thyrocytes is unclear. Congenital hypothyroidism (CH) is defined as the lack of TH at birth. In familial cases, high-throughput sequencing methods have facilitated the identification of novel mutations. Nevertheless, the precise etiology of CH yet remains unraveled in a proportion of cases. Genetically modified mouse models can reveal new pathophysiological mechanisms of thyroid diseases. Here, we will present an overview of genetic mouse models for thyroid diseases, which have provided crucial insights into thyroid gland development, function, and growth with a special focus on TSHR and microRNA signaling.
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Affiliation(s)
- C Löf
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - K Patyra
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - A Kero
- Department of Pediatrics, Turku University Hospital, Kiinamyllynkatu 4-8, 20521, Turku, Finland
| | - J Kero
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland; Department of Pediatrics, Turku University Hospital, Kiinamyllynkatu 4-8, 20521, Turku, Finland.
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Patyra K, Jaeschke H, Löf C, Jännäri M, Ruohonen ST, Undeutsch H, Khalil M, Kero A, Poutanen M, Toppari J, Chen M, Weinstein LS, Paschke R, Kero J. Partial thyrocyte-specific Gα s deficiency leads to rapid-onset hypothyroidism, hyperplasia, and papillary thyroid carcinoma-like lesions in mice. FASEB J 2018; 32:fj201800211R. [PMID: 29799790 DOI: 10.1096/fj.201800211r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Thyroid function is controlled by thyroid-stimulating hormone (TSH), which binds to its G protein-coupled receptor [thyroid-stimulating hormone receptor (TSHR)] on thyrocytes. TSHR can potentially couple to all G protein families, but it mainly activates the Gs- and Gq/11-mediated signaling cascades. To date, there is a knowledge gap concerning the role of the individual G protein cascades in thyroid pathophysiology. Here, we demonstrate that the thyrocyte-specific deletion of Gs-protein α subunit (Gαs) in adult mice [tamoxifen-inducible Gs protein α subunit deficient (iTGαsKO) mice] rapidly impairs thyrocyte function and leads to hypothyroidism. Consequently, iTGαsKO mice show reduced food intake and activity. However, body weight and the amount of white adipose tissue were decreased only in male iTGαsKO mice. Unexpectedly, hyperplastic follicles and papillary thyroid cancer-like tumor lesions with increased proliferation and slightly increased phospho-ERK1/2 staining were found in iTGαsKO mice at an older age. These tumors developed from nonrecombined thyrocytes still expressing Gαs in the presence of highly elevated serum TSH. In summary, we report that partial thyrocyte-specific Gαs deletion leads to hypothyroidism but also to tumor development in thyrocytes with remaining Gαs expression. Thus, these mice are a novel model to elucidate the pathophysiological consequences of hypothyroidism and TSHR/Gs/cAMP-mediated tumorigenesis.-Patyra, K., Jaeschke, H., Löf, C., Jännäri, M., Ruohonen, S. T., Undeutsch, H., Khalil, M., Kero, A., Poutanen, M., Toppari, J., Chen, M., Weinstein, L. S., Paschke, R., Kero, J. Partial thyrocyte-specific Gαs deficiency leads to rapid-onset hypothyroidism, hyperplasia, and papillary thyroid carcinoma-like lesions in mice.
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Affiliation(s)
- Konrad Patyra
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Holger Jaeschke
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Christoffer Löf
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Meeri Jännäri
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Suvi T Ruohonen
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Henriette Undeutsch
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Moosa Khalil
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary,
Alberta, Canada
| | - Andreina Kero
- Department of Pediatrics, Turku University Hospital, Finland
| | - Matti Poutanen
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Jorma Toppari
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
- Department of Pediatrics, Turku University Hospital, Finland
| | - Min Chen
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Lee S Weinstein
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Ralf Paschke
- Arnie Charbonneau Cancer Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jukka Kero
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Department of Pediatrics, Turku University Hospital, Finland
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Berndt-Paetz M, Herbst L, Weimann A, Gonsior A, Stolzenburg JU, Neuhaus J. Highly specific detection of muscarinic M3 receptor, G protein interaction and intracellular trafficking in human detrusor using Proximity Ligation Assay (PLA). Acta Histochem 2018; 120:329-339. [PMID: 29551457 DOI: 10.1016/j.acthis.2018.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 02/08/2018] [Accepted: 03/09/2018] [Indexed: 01/06/2023]
Abstract
PURPOSE Muscarinic acetylcholine receptors (mAChRs) regulate a number of important physiological functions. Alteration of mAChR expression or function has been associated in the etiology of several pathologies including functional bladder disorders (e.g bladder pain syndrome/interstitial cystitis - BPS/IC). In a previous study we found specific mAChR expression patterns associated with BPS/IC, while correlation between protein and gene expression was lacking. Posttranslational regulatory mechanisms, e.g. altered intracellular receptor trafficking, could explain those differences. In addition, alternative G protein (GP) coupling could add to the pathophysiology via modulation of muscarinic signaling. In our proof-of-principle study, we addressed these questions in situ. We established PLA in combination with confocal laserscanning microscopy (CLSM) and 3D object reconstruction for highly specific detection and analysis of muscarinic 3 receptors (M3), G protein (GP) coupling and intracellular trafficking in human detrusor samples. MATERIAL AND METHODS Paraffin sections of formalin-fixed bladder tissue (FFPE) of BPS/IC patients receiving transurethral biopsy were examined by Cy3-PLA for M3 expression, coupling of M3 to GPs (Gαq/11, Gαs, Gαi) and interaction of M3 with endocytic regulator proteins. Membranes were labeled with wheat germ agglutinin-Alexa Fluor®488, nuclei were stained with DAPI. Object density and co-localization were analyzed in 3D-reconstruction of high resolution confocal z-stacks. RESULTS Confocal image stack processing resulted in well demarcated objects. Calculated receptor densities correlated significantly with existing confocal expression data, while significantly improved specificity of M3 detection by PLA was verified using bladder tissue samples from transgenic mice. 50-60% of the M3 receptor complexes were plasma membrane associated in human bladder detrusor. Application of PLA for M3 and GPs allowed visualization of M3-GP interactions and revealed individual GP-subtype coupling patterns. Detection of M3 interactions with endocytic trafficking proteins by PLA resulted in object sizes correlating with well-documented vesicle sizes of the endocytosis pathway. CONCLUSION PLA enabled highly specific detection of M3 receptor expression, demonstration of M3/GP differential coupling and intracellular M3 trafficking in human detrusor smooth muscle cells. This new approach minimized background fluorescence and antibody cross-reactions resulting from single antibody application, and enhanced specificity due to the use of two primary antibodies. Use of subcellular markers allowed visualization of subcellular receptor location. PLA/CLSM allows analyses of muscarinic "receptor - G protein - promiscuity" and intracellular trafficking even in bladder paraffin sections and may give new insights into the etiology and pathology of BPS/IC.
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Briet C, Suteau-Courant V, Munier M, Rodien P. Thyrotropin receptor, still much to be learned from the patients. Best Pract Res Clin Endocrinol Metab 2018; 32:155-164. [PMID: 29678283 DOI: 10.1016/j.beem.2018.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In the absence of crystal available for the full-length thyrotropin receptor, knowledge of its structure and functioning has benefitted from the identification and characterization of mutations in patients with various thyroid dysfunctions. The characterization of activating mutations has contributed to the elaboration of a model involving the extracellular domain of the receptor as an inverse tethered agonist which, upon binding of the ligand, relieves the transmembrane domain from an inhibiting interaction and activates it. The models derived from comparisons with other receptors, enriched with the information provided by the study of mutations, have proven useful for the design of small-molecule agonists and antagonists that may be used in the future to treat thyroid dysfunctions. In this review, extrathyroidal expression of the thyrotropin receptor is described, the role of which is still poorly defined.
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Affiliation(s)
- Claire Briet
- Centre de Référence des Maladies Rares de la Thyroïde et des Récepteurs Hormonaux, Centre Hospitalo-Universitaire d'Angers, 4 Rue Larrey, Angers, France; Institut MITOVASC, UMR CNRS 6015, INSERM 1083, Université d'Angers, France.
| | - Valentine Suteau-Courant
- Centre de Référence des Maladies Rares de la Thyroïde et des Récepteurs Hormonaux, Centre Hospitalo-Universitaire d'Angers, 4 Rue Larrey, Angers, France; Institut MITOVASC, UMR CNRS 6015, INSERM 1083, Université d'Angers, France.
| | - Mathilde Munier
- Centre de Référence des Maladies Rares de la Thyroïde et des Récepteurs Hormonaux, Centre Hospitalo-Universitaire d'Angers, 4 Rue Larrey, Angers, France; Institut MITOVASC, UMR CNRS 6015, INSERM 1083, Université d'Angers, France.
| | - Patrice Rodien
- Centre de Référence des Maladies Rares de la Thyroïde et des Récepteurs Hormonaux, Centre Hospitalo-Universitaire d'Angers, 4 Rue Larrey, Angers, France; Institut MITOVASC, UMR CNRS 6015, INSERM 1083, Université d'Angers, France.
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Mouillac B, Mendre C. Pharmacological Chaperones as Potential Therapeutic Strategies for Misfolded Mutant Vasopressin Receptors. Handb Exp Pharmacol 2018; 245:63-83. [PMID: 28939971 DOI: 10.1007/164_2017_50] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pharmacological chaperones recently opened new possibilities in G protein-coupled receptor drug discovery. Even more interestingly, some unique ligands combine pharmacological chaperoning and biased agonism properties, boosting their therapeutic interest in many human diseases resulting from G protein-coupled receptor mutation and misfolding. These compounds displaying dual characteristics would constitute a perfect treatment for congenital Nephrogenic Diabetes Insipidus, a typical conformational disease. This X-linked genetic pathology is mostly associated with inactivating mutations of the renal arginine-vasopressin V2 receptor leading to misfolding and intracellular retention of the receptor, causing the inability of patients to concentrate their urine in response to the antidiuretic hormone. Cell-permeable pharmacological chaperones have been successfully challenged to restore plasma membrane localization of many V2 receptor mutants. In addition, different classes of specific ligands such as antagonists, agonists as well as biased agonists of the V2 receptor have proven their usefulness in rescuing mutant receptor function. This is particularly relevant for small-molecule biased agonists which only trigger Gs protein activation and cyclic adenosine monophosphate production, the V2-induced signaling pathway responsible for water reabsorption. In parallel, high-throughput screening assays based on receptor trafficking rescue approaches have been developed to discover novel V2 pharmacological chaperone molecules from different chemical libraries. These new hit compounds, which still need to be pharmacologically characterized and functionally tested in vivo, represent promising candidates for the treatment of congenital Nephrogenic Diabetes Insipidus.
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Affiliation(s)
- Bernard Mouillac
- Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, 141 rue de la cardonille, 34094, Montpellier Cedex 05, France.
| | - Christiane Mendre
- Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, 141 rue de la cardonille, 34094, Montpellier Cedex 05, France
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Neumann S, Eliseeva E, Boutin A, Barnaeva E, Ferrer M, Southall N, Kim D, Hu X, Morgan SJ, Marugan JJ, Gershengorn MC. Discovery of a Positive Allosteric Modulator of the Thyrotropin Receptor: Potentiation of Thyrotropin-Mediated Preosteoblast Differentiation In Vitro. J Pharmacol Exp Ther 2017; 364:38-45. [PMID: 29089368 DOI: 10.1124/jpet.117.244095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 10/26/2017] [Indexed: 01/01/2023] Open
Abstract
Recently, we showed that TSH-enhanced differentiation of a human preosteoblast-like cell model involved a β-arrestin 1 (β-Arr 1)-mediated pathway. To study this pathway in more detail, we sought to discover a small molecule ligand that was functionally selective toward human TSH receptor (TSHR) activation of β-Arr 1. High-throughput screening using a cell line stably expressing mutated TSHRs and mutated β-Arr 1 (DiscoverX1 cells) led to the discovery of agonists that stimulated translocation of β-Arr 1 to the TSHR, but did not activate Gs-mediated signaling pathways, i.e., cAMP production. D3-βArr (NCGC00379308) was selected. In DiscoverX1 cells, D3-βArr stimulated β-Arr 1 translocation with a 5.1-fold greater efficacy than TSH and therefore potentiated the effect of TSH in stimulating β-Arr 1 translocation. In human U2OS-TSHR cells expressing wild-type TSHRs, which is a model of human preosteoblast-like cells, TSH upregulated the osteoblast-specific genes osteopontin (OPN) and alkaline phosphatase (ALPL). D3-βArr alone had only a weak effect to upregulate these bone markers, but D3-βArr potentiated TSH-induced upregulation of ALPL and OPN mRNA levels 1.6-fold and 5.5-fold, respectively, at the maximum dose of ligands. Furthermore, the positive allosteric modulator effect of D3-βArr resulted in an increase of TSH-induced secretion of OPN protein. In summary, we have discovered the first small molecule positive allosteric modulator of TSHR. As D3-βArr potentiates the effect of TSH to enhance differentiation of a human preosteoblast in an in vitro model, it will allow a novel experimental approach for probing the role of TSH-induced β-Arr 1 signaling in osteoblast differentiation.
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Affiliation(s)
- Susanne Neumann
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Elena Eliseeva
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Alisa Boutin
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Elena Barnaeva
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Marc Ferrer
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Noel Southall
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - David Kim
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Xin Hu
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Sarah J Morgan
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Juan J Marugan
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
| | - Marvin C Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (S.N., E.E., A.B., S.J.M., M.C.G.); and Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland (E.B., M.F., N.S., D.K., X.H., J.J.M.)
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Krieger CC, Perry JD, Morgan SJ, Kahaly GJ, Gershengorn MC. TSH/IGF-1 Receptor Cross-Talk Rapidly Activates Extracellular Signal-Regulated Kinases in Multiple Cell Types. Endocrinology 2017; 158:3676-3683. [PMID: 28938449 PMCID: PMC5659693 DOI: 10.1210/en.2017-00528] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/08/2017] [Indexed: 12/25/2022]
Abstract
We previously showed that thyrotropin (TSH)/insulinlike growth factor (IGF)-1 receptor cross-talk appears to be involved in Graves' orbitopathy (GO) pathogenesis and upregulation of thyroid-specific genes in human thyrocytes. In orbital fibroblasts from GO patients, coadministration of TSH and IGF-1 induces synergistic increases in hyaluronan secretion. In human thyrocytes, TSH plus IGF-1 synergistically increased expression of the sodium-iodide symporter that appeared to involve ERK1/2 activation. However, the details of ERK1/2 activation were not known, nor was whether ERK1/2 was involved in this synergism in other cell types. Using primary cultures of GO fibroblasts (GOFs) and human thyrocytes, as well as human embryonic kidney (HEK) 293 cells overexpressing TSH receptors (HEK-TSHRs), we show that simultaneous activation of TSHRs and IGF-1 receptors (IGF-1Rs) causes rapid, synergistic phosphorylation/activation of ERK1 and ERK2 in all three cell types. This effect is partially inhibited by pertussis toxin, an inhibitor of TSHR coupling to Gi/Go proteins. In support of a role for Gi/Go proteins in ERK1/2 phosphorylation, we found that knockdown of Gi(1-3) and Go in HEK-TSHRs inhibited ERK1/2 phosphorylation stimulated by TSH and TSH plus IGF-1. These data demonstrate that the synergistic effects of TSH plus IGF-1 occur early in the TSHR signaling cascade and further support the idea that TSHR/IGF-1R cross-talk is an important mechanism for regulation of human GOFs and thyrocytes.
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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 20892
| | - Joseph D. Perry
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Sarah J. Morgan
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - George J. Kahaly
- Molecular Thyroid Research Laboratory, Department of Medicine I, Johannes Gutenberg University Medical Center, Langenbeckstreet 1, 55131 Mainz, Germany
| | - Marvin C. Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Finlay DB, Cawston EE, Grimsey NL, Hunter MR, Korde A, Vemuri VK, Makriyannis A, Glass M. Gα s signalling of the CB 1 receptor and the influence of receptor number. Br J Pharmacol 2017; 174:2545-2562. [PMID: 28516479 PMCID: PMC5513864 DOI: 10.1111/bph.13866] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/30/2017] [Accepted: 05/09/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND PURPOSE CB1 receptor signalling is canonically mediated through inhibitory Gαi proteins, but occurs through other G proteins under some circumstances, Gαs being the most characterized secondary pathway. Determinants of this signalling switch identified to date include Gαi blockade, CB1 /D2 receptor co-stimulation, CB1 agonist class and cell background. Hence, we examined the effects of receptor number and different ligands on CB1 receptor signalling. EXPERIMENTAL APPROACH CB1 receptors were expressed in HEK cells at different levels, and signalling characterized for cAMP by real-time BRET biosensor -CAMYEL - and for phospho-ERK by AlphaScreen. Homogenate and whole cell radioligand binding assays were performed to characterize AM6544, a novel irreversible CB1 receptor antagonist. KEY RESULTS In HEK cells expressing high levels of CB1 receptors, agonist treatment stimulated cAMP, a response not known to be mediated by receptor number. Δ9 -THC and BAY59-3074 increased cAMP only in high-expressing cells pretreated with pertussis toxin, and agonists demonstrated more diverse signalling profiles in the stimulatory pathway than the canonical inhibitory pathway. Pharmacological CB1 receptor knockdown and Gαi 1 supplementation restored canonical Gαi signalling to high-expressing cells. Constitutive signalling in both low- and high-expressing cells was Gαi -mediated. CONCLUSION AND IMPLICATIONS CB1 receptor coupling to opposing G proteins is determined by both receptor and G protein expression levels, which underpins a mechanism for non-canonical signalling in a fashion consistent with Gαs signalling. CB1 receptors mediate opposite consequences in endpoints such as tumour viability depending on expression levels; our results may help to explain such effects at the level of G protein coupling.
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Affiliation(s)
- David B Finlay
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Erin E Cawston
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Natasha L Grimsey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Morag R Hunter
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Anisha Korde
- Center for Drug DiscoveryNortheastern UniversityBostonMAUSA
| | - V Kiran Vemuri
- Center for Drug DiscoveryNortheastern UniversityBostonMAUSA
| | | | - Michelle Glass
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
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Abstract
INTRODUCTION The availability of different functional pharmacological assays has revealed that agonists for receptors that are pleiotropically coupled to multiple signaling pathways in the cell can emphasize signals to some pathways over others, i.e. can be biased toward certain signals. This, in turn, opens the possibility that molecules can be made to emphasize favorable signals, de-emphasize harmful signals or selectively block the ability of the natural agonist to produce unfavorable signals. Areas covered: This paper discusses the mechanism of biased signaling, the possible therapeutic implications of this effect, methods to quantify and measure bias and the current literature describing the translation of biased measure in vitro to in vivo systems. In addition, the challenges of exploiting this mechanism for therapy are outlined. Expert opinion: While this mechanism is well established and ubiquitous in pharmacology and easily measured in vitro, there are theoretical and practical hurdles to overcome to the fruitful utilization of signaling bias in therapeutic systems. There will be failures in the translation of biased molecules in vivo because of these challenges but hopefully also success and these latter translations hopefully will provide guidance in exploiting this effect further for therapy.
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Affiliation(s)
- Terry Kenakin
- a Department of Pharmacology , University of North Carolina School of Medicine , Chapel Hill , NC , USA
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Jara EL, Muñoz-Durango N, Llanos C, Fardella C, González PA, Bueno SM, Kalergis AM, Riedel CA. Modulating the function of the immune system by thyroid hormones and thyrotropin. Immunol Lett 2017; 184:76-83. [PMID: 28216261 DOI: 10.1016/j.imlet.2017.02.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/14/2017] [Accepted: 02/15/2017] [Indexed: 12/18/2022]
Abstract
Accumulating evidence suggests a close bidirectional communication and regulation between the neuroendocrine and immune systems. Thyroid hormones (THs) can exert responses in various immune cells, e.g., monocytes, macrophages, natural killer cells, and lymphocytes, affecting several inflammation-related processes (such as, chemotaxis, phagocytosis, reactive oxygen species generation, and cytokines production). The interactions between the endocrine and immune systems have been shown to contribute to pathophysiological conditions, including sepsis, inflammation, autoimmune diseases and viral infections. Under these conditions, TH therapy could contribute to restoring normal physiological functions. Here we discuss the effects of THs and thyroid stimulating hormone (TSH) on the immune system and the contribution to inflammation and pathogen clearance, as well as the consequences of thyroid pathologies over the function of the immune system.
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Affiliation(s)
- Evelyn L Jara
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Natalia Muñoz-Durango
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Carolina Llanos
- Departamento de Inmunología Clínica y Reumatología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 350, Santiago, Chile
| | - Carlos Fardella
- Millennium Institute on Immunology and Immunotherapy, Departamento de Endocrinología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 350, Santiago, Chile
| | - Pablo A González
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Susan M Bueno
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile; Millennium Institute on Immunology and Immunotherapy, Departamento de Endocrinología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 350, Santiago, Chile; INSERM U1064, Nantes, France.
| | - Claudia A Riedel
- Millenium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas y Facultad de Medicina, Universidad Andrés Bello, Chile.
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Abstract
INTRODUCTION Graves' disease (GD) and thyroid-associated ophthalmopathy (TAO) are thought to result from actions of pathogenic antibodies mediated through the thyrotropin receptor (TSHR). This leads to the unregulated consequences of the antibody-mediated receptor activity in the thyroid and connective tissues of the orbit. Recent studies reveal antibodies that appear to be directed against the insulin-like growth factor-I receptor (IGF-IR). Areas covered: In this brief article, I attempt to review the fundamental characteristics of the TSHR, its role in GD and TAO, and its relationship to IGF-IR. Strong evidence supports the concept that the two receptors form a physical and functional complex and that IGF-IR activity is required for some of the down-stream signaling initiated through TSHR. Recently developed small molecules and monoclonal antibodies that block TSHR and IGF-IR signaling are also reviewed in the narrow context of their potential utility as therapeutics in GD and TAO. The Pubmed database was searched from its inception for relevant publications. Expert opinion: Those agents that can interrupt the TSHR and IGF-IR pathways possess the potential for offering more specific and better tolerated treatments of both hyperthyroidism and TAO. This would spare patients exposure to toxic drugs, ionizing radiation and potentially hazardous surgeries.
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Affiliation(s)
- Terry Smith
- a Department of Ophthalmology and Visual Sciences , University of Michigan , Ann Arbor , MI , USA
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Kleinau G, Worth CL, Kreuchwig A, Biebermann H, Marcinkowski P, Scheerer P, Krause G. Structural-Functional Features of the Thyrotropin Receptor: A Class A G-Protein-Coupled Receptor at Work. Front Endocrinol (Lausanne) 2017; 8:86. [PMID: 28484426 PMCID: PMC5401882 DOI: 10.3389/fendo.2017.00086] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/03/2017] [Indexed: 12/21/2022] Open
Abstract
The thyroid-stimulating hormone receptor (TSHR) is a member of the glycoprotein hormone receptors, a sub-group of class A G-protein-coupled receptors (GPCRs). TSHR and its endogenous ligand thyrotropin (TSH) are of essential importance for growth and function of the thyroid gland and proper function of the TSH/TSHR system is pivotal for production and release of thyroid hormones. This receptor is also important with respect to pathophysiology, such as autoimmune (including ophthalmopathy) or non-autoimmune thyroid dysfunctions and cancer development. Pharmacological interventions directly targeting the TSHR should provide benefits to disease treatment compared to currently available therapies of dysfunctions associated with the TSHR or the thyroid gland. Upon TSHR activation, the molecular events conveying conformational changes from the extra- to the intracellular side of the cell across the membrane comprise reception, conversion, and amplification of the signal. These steps are highly dependent on structural features of this receptor and its intermolecular interaction partners, e.g., TSH, antibodies, small molecules, G-proteins, or arrestin. For better understanding of signal transduction, pathogenic mechanisms such as autoantibody action and mutational modifications or for developing new pharmacological strategies, it is essential to combine available structural data with functional information to generate homology models of the entire receptor. Although so far these insights are fragmental, in the past few decades essential contributions have been made to investigate in-depth the involved determinants, such as by structure determination via X-ray crystallography. This review summarizes available knowledge (as of December 2016) concerning the TSHR protein structure, associated functional aspects, and based on these insights we suggest several receptor complex models. Moreover, distinct TSHR properties will be highlighted in comparison to other class A GPCRs to understand the molecular activation mechanisms of this receptor comprehensively. Finally, limitations of current knowledge and lack of information are discussed highlighting the need for intensified efforts toward TSHR structure elucidation.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin, Berlin, Germany
- Group Protein X-Ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin, Berlin, Germany
| | | | - Annika Kreuchwig
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin, Berlin, Germany
| | | | - Patrick Scheerer
- Group Protein X-Ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin, Berlin, Germany
| | - Gerd Krause
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
- *Correspondence: Gerd Krause,
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49
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Press O, Zvagelsky T, Vyazmensky M, Kleinau G, Engel S. Construction of Structural Mimetics of the Thyrotropin Receptor Intracellular Domain. Biophys J 2016; 111:2620-2628. [PMID: 28002738 PMCID: PMC5192603 DOI: 10.1016/j.bpj.2016.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/26/2016] [Accepted: 11/02/2016] [Indexed: 10/20/2022] Open
Abstract
The signaling of a G protein-coupled receptor (GPCR) is dictated by the complementary responsiveness of interacting intracellular effectors such as G proteins. Many GPCRs are known to couple to more than one G protein subtype and induce a multitude of signaling pathways, although the in vivo relevance of particular pathways is mostly unrecognized. Dissecting GPCR signaling in terms of the pathways that are activated will boost our understanding of the molecular fundamentals of hormone action. The structural determinants governing the selectivity of GPCR/G protein coupling, however, remain obscure. Here, we describe the design of soluble GPCR mimetics to study the details of the interplay between G-proteins and activators. We constructed functional mimetics of the intracellular domain of a model GPCR, the thyrotropin receptor. We based the construction on a unique scaffold, 6-Helix, an artificial protein that was derived from the elements of the trimer-of-hairpins structure of HIV gp41 and represents a bundle of six α-helices. The 6-Helix scaffold, which endowed the substituted thyrotropin receptor intracellular domain elements with spatial constraints analogous to those found in native receptors, enabled the reconstitution of a microdomain that consists of intracellular loops 2 and 3, and is capable of binding and activating Gα-(s). The 6-Helix-based mimetics could be used as a platform to study the molecular basis of GPCR/G protein recognition. Such knowledge could help investigators develop novel therapeutic strategies for GPCR-related disorders by targeting the GPCR/G protein interfaces and counteracting cellular dysfunctions via focused tuning of GPCR signaling.
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Affiliation(s)
- Olga Press
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tatiana Zvagelsky
- Department of Chemistry, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Maria Vyazmensky
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin, Berlin, Germany
| | - Stanislav Engel
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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50
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Müller A, Berkmann JC, Scheerer P, Biebermann H, Kleinau G. Insights into Basal Signaling Regulation, Oligomerization, and Structural Organization of the Human G-Protein Coupled Receptor 83. PLoS One 2016; 11:e0168260. [PMID: 27936173 PMCID: PMC5148169 DOI: 10.1371/journal.pone.0168260] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/29/2016] [Indexed: 12/22/2022] Open
Abstract
The murine G-protein coupled receptor 83 (mGPR83) is expressed in the hypothalamus and was previously suggested to be involved in the regulation of metabolism. The neuropeptide PEN has been recently identified as a potent GPR83 ligand. Moreover, GPR83 constitutes functionally relevant hetero-oligomers with other G-protein coupled receptors (GPCR) such as the ghrelin receptor (GHSR) or GPR171. Previous deletion studies also revealed that the long N-terminal extracellular receptor domain (eNDo) of mGPR83 may act as an intra-molecular ligand, which participates in the regulation of basal signaling activity, which is a key feature of GPCR function. Here, we investigated particular amino acids at the eNDo of human GPR83 (hGPR83) by side-directed mutagenesis to identify determinants of the internal ligand. These studies were accompanied by structure homology modeling to combine functional insights with structural information. The capacity for hetero-oligomer formation of hGPR83 with diverse family A GPCRs such as the melanocortin-4 receptor (MC4R) was also investigated, with a specific emphasis on the impact of the eNDo on oligomerization and basal signaling properties. Finally, we demonstrate that hGPR83 exhibits an unusual basal signaling for different effectors, which also supports signaling promiscuity. hGPR83 interacts with a variety of hypothalamic GPCRs such as the MC4R or GHSR. These interactions are not dependent on the ectodomain and most likely occur at interfaces constituted in the transmembrane regions. Moreover, several amino acids at the transition between the eNDo and transmembrane helix 1 were identified, where mutations lead also to biased basal signaling modulation.
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Affiliation(s)
- Anne Müller
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Julia Catherine Berkmann
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Patrick Scheerer
- Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
- * E-mail:
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