1
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Nagayama Y, Nishihara E. Thyrotropin receptor antagonists and inverse agonists, and their potential application to thyroid diseases. Endocr J 2022; 69:1285-1293. [PMID: 36171093 DOI: 10.1507/endocrj.ej22-0391] [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
The thyrotropin receptor (TSHR) plays critical roles in thyroid growth and function and in the pathogenesis of several thyroid diseases including Graves' hyperthyroidism and ophthalmopathy, non-autoimmune hyperthyroidism and thyroid cancer. Several low-molecular weight compounds (LMWCs) and anti-TSHR monoclonal antibodies (mAbs) with receptor antagonistic and inverse agonistic activities have been reported. The former binds to the pocket formed by the receptor transmembrane bundle, and the latter to the extracellular TSH binding site. Both are effective inhibitors of TSH/thyroid stimulating antibody-stimulated cAMP and/or hyaluronic acid production in TSHR-expressing cells. Anti-insulin-like growth factor 1 inhibitors are also found to inhibit TSHR signaling. Each agent has advantages and disadvantages; for example, mAbs have a higher affinity and longer half-life but are more costly than LMWCs. At present, mAbs appear most promising, yet the development of more efficacious LMWCs is desirable. These agents are anticipated to be efficacious not only for the above-mentioned diseases but also for resistance to thyroid hormone and have utility for thyroid cancer radionuclide scintigraphy/therapy as a new theranostic.
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Affiliation(s)
- Yuji Nagayama
- Department of Molecular Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki 852-8523, Japan
| | - Eijun Nishihara
- Center for Excellence in Thyroid Care, Kuma Hospital, Kobe 650-0011, Japan
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2
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Faust B, Billesbølle CB, Suomivuori CM, Singh I, Zhang K, Hoppe N, Pinto AFM, Diedrich JK, Muftuoglu Y, Szkudlinski MW, Saghatelian A, Dror RO, Cheng Y, Manglik A. Autoantibody mimicry of hormone action at the thyrotropin receptor. Nature 2022; 609:846-853. [PMID: 35940205 PMCID: PMC9678024 DOI: 10.1038/s41586-022-05159-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 07/28/2022] [Indexed: 11/08/2022]
Abstract
Thyroid hormones are vital in metabolism, growth and development1. Thyroid hormone synthesis is controlled by thyrotropin (TSH), which acts at the thyrotropin receptor (TSHR)2. In patients with Graves' disease, autoantibodies that activate the TSHR pathologically increase thyroid hormone activity3. How autoantibodies mimic thyrotropin function remains unclear. Here we determined cryo-electron microscopy structures of active and inactive TSHR. In inactive TSHR, the extracellular domain lies close to the membrane bilayer. Thyrotropin selects an upright orientation of the extracellular domain owing to steric clashes between a conserved hormone glycan and the membrane bilayer. An activating autoantibody from a patient with Graves' disease selects a similar upright orientation of the extracellular domain. Reorientation of the extracellular domain transduces a conformational change in the seven-transmembrane-segment domain via a conserved hinge domain, a tethered peptide agonist and a phospholipid that binds within the seven-transmembrane-segment domain. Rotation of the TSHR extracellular domain relative to the membrane bilayer is sufficient for receptor activation, revealing a shared mechanism for other glycoprotein hormone receptors that may also extend to other G-protein-coupled receptors with large extracellular domains.
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MESH Headings
- Cell Membrane/metabolism
- Cryoelectron Microscopy
- Graves Disease/immunology
- Graves Disease/metabolism
- Humans
- Immunoglobulins, Thyroid-Stimulating/chemistry
- Immunoglobulins, Thyroid-Stimulating/immunology
- Immunoglobulins, Thyroid-Stimulating/pharmacology
- Immunoglobulins, Thyroid-Stimulating/ultrastructure
- Phospholipids/metabolism
- Protein Domains
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/ultrastructure
- Receptors, Thyrotropin/agonists
- Receptors, Thyrotropin/chemistry
- Receptors, Thyrotropin/immunology
- Receptors, Thyrotropin/ultrastructure
- Rotation
- Thyrotropin/chemistry
- Thyrotropin/metabolism
- Thyrotropin/pharmacology
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Affiliation(s)
- Bryan Faust
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
- Biophysics Graduate Program, University of California, San Francisco, CA, USA
| | | | - Carl-Mikael Suomivuori
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Isha Singh
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Kaihua Zhang
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Nicholas Hoppe
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
- Biophysics Graduate Program, University of California, San Francisco, CA, USA
| | - Antonio F M Pinto
- Mass Spectrometry Core for Proteomics and Metabolomics, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Jolene K Diedrich
- Mass Spectrometry Core for Proteomics and Metabolomics, Salk Institute for Biological Studies, La Jolla, CA, USA
| | | | | | - Alan Saghatelian
- Clayton Foundation Laboratory for Peptide Biology Lab, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.
- Biophysics Graduate Program, University of California, San Francisco, CA, USA.
- Howard Hughes Medical Institute, University of California, San Francisco, CA, USA.
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA.
- Biophysics Graduate Program, University of California, San Francisco, CA, USA.
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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3
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Fokina EF, Shpakov AO. Thyroid-Stimulating Hormone Receptor: the Role in the Development of Thyroid Pathology and Its Correction. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022050143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract
One of the key elements responsible for the thyroid response
to thyroid-stimulating hormone (TSH) is the TSH receptor (TSHR),
which belongs to the G protein-coupled receptor superfamily. Binding
of TSH or stimulatory autoantibodies to the TSHR extracellular domain
triggers multiple signaling pathways in target cells that are mediated
through various types of G proteins and β-arrestins. Inhibitory
autoantibodies, in contrast, suppress TSHR activity, inducing hypothyroid states.
Activating mutations lead to constitutively active TSHR forms and
can trigger cancer. Therefore, the TSHR is one of the key targets
for the regulation of thyroid function and thyroid status, as well
as correction of diseases caused by changes in TSHR activity (autoimmune
hyper- and hypothyroidism, Graves’ ophthalmopathy, thyroid cancer).
TSH preparations are extremely rarely used in medicine due to their
immunogenicity and severe side effects. Most promising is the development
of low-molecular allosteric TSHR regulators with an activity of
full and inverse agonists and neutral antagonists, which are able
to penetrate into the allosteric site located in the TSHR transmembrane
domain and specifically bind to it, thus controlling the ability
of the receptor to interact with G proteins and β-arrestins. Allosteric
regulators do not affect the binding of TSH and autoantibodies to
the receptor, which enables mild and selective regulation of thyroid function,
while avoiding critical changes in TSH and thyroid hormone levels.
The present review addresses the current state of the problem of
regulating TSHR activity, including the possibility of using ligands
of its allosteric sites.
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4
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Ulloa-Aguirre A, Zariñán T, Jardón-Valadez E. Misfolded G Protein-Coupled Receptors and Endocrine Disease. Molecular Mechanisms and Therapeutic Prospects. Int J Mol Sci 2021; 22:ijms222212329. [PMID: 34830210 PMCID: PMC8622668 DOI: 10.3390/ijms222212329] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/28/2021] [Accepted: 10/01/2021] [Indexed: 11/30/2022] Open
Abstract
Misfolding of G protein-coupled receptors (GPCRs) caused by mutations frequently leads to disease due to intracellular trapping of the conformationally abnormal receptor. Several endocrine diseases due to inactivating mutations in GPCRs have been described, including X-linked nephrogenic diabetes insipidus, thyroid disorders, familial hypocalciuric hypercalcemia, obesity, familial glucocorticoid deficiency [melanocortin-2 receptor, MC2R (also known as adrenocorticotropin receptor, ACTHR), and reproductive disorders. In these mutant receptors, misfolding leads to endoplasmic reticulum retention, increased intracellular degradation, and deficient trafficking of the abnormal receptor to the cell surface plasma membrane, causing inability of the receptor to interact with agonists and trigger intracellular signaling. In this review, we discuss the mechanisms whereby mutations in GPCRs involved in endocrine function in humans lead to misfolding, decreased plasma membrane expression of the receptor protein, and loss-of-function diseases, and also describe several experimental approaches employed to rescue trafficking and function of the misfolded receptors. Special attention is given to misfolded GPCRs that regulate reproductive function, given the key role played by these particular membrane receptors in sexual development and fertility, and recent reports on promising therapeutic interventions targeting trafficking of these defective proteins to rescue completely or partially their normal function.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Red de Apoyo a la Investigación, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City 14080, Mexico;
- Correspondence:
| | - Teresa Zariñán
- Red de Apoyo a la Investigación, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City 14080, Mexico;
| | - Eduardo Jardón-Valadez
- Departamento de Recursos de la Tierra, Universidad Autónoma Metropolitana-Lerma, Lerma de Villada 52005, Estado de México, Mexico;
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Smith TJ. Thyroid-associated ophthalmopathy: Emergence of teprotumumab as a promising medical therapy. Best Pract Res Clin Endocrinol Metab 2020; 34:101383. [PMID: 32088116 PMCID: PMC7344338 DOI: 10.1016/j.beem.2020.101383] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Thyroid-associated ophthalmopathy (TAO) remains a vexing autoimmune component of Graves' disease that can diminish the quality of life as a consequence of its impact on visual function, physical appearance and emotional well-being. Because of its relative rarity and variable presentation, the development of highly effective and well-tolerated medical therapies for TAO has been slow relative to other autoimmune diseases. Contributing to the barriers of greater insight into TAO has been the historical absence of high-fidelity preclinical animal models. Despite these challenges, several agents, most developed for treatment of other diseases, have found their way into consideration for use in active TAO through repurposing. Among these, teprotumumab is a fully human inhibitory monoclonal antibody against the insulin-like growth factor I receptor. It has shown remarkable effectiveness in moderate to severe, active TAO in two completed multicenter, double masked, and placebo controlled clinical trials. The drug exhibits a favorable safety profile. Teprotumumab has recently been approved by the U.S. F.D.A, and may rapidly become the first line therapy for this disfiguring and potentially blinding condition.
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Affiliation(s)
- Terry J Smith
- Department of Ophthalmology and Visual Sciences, Room 7112, Brehm Tower, University of Michigan Medical School, 1000 Wall Street, Ann Arbor, MI, 48105, USA.
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6
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Smith TJ, Bartalena L. Will biological agents supplant systemic glucocorticoids as the first-line treatment for thyroid-associated ophthalmopathy? Eur J Endocrinol 2019; 181:D27-D43. [PMID: 31370005 PMCID: PMC7398270 DOI: 10.1530/eje-19-0389] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/30/2019] [Indexed: 12/14/2022]
Abstract
In this article, the two authors present their opposing points of view concerning the likelihood that glucocorticoids will be replaced by newly developed biological agents in the treatment of active, moderate-to-severe thyroid-associated ophthalmopathy (TAO). TAO is a vexing, disfiguring and potentially blinding autoimmune manifestation of thyroid autoimmunity. One author expresses the opinion that steroids are nonspecific, frequently fail to improve the disease and can cause sometimes serious side effects. He suggests that glucocorticoids should be replaced as soon as possible by more specific and safer drugs, once they become available. The most promising of these are biological agents. The other author argues that glucocorticoids are proven effective and are unlikely to be replaced by biologicals. He reasons that while they may not uniformly result in optimal benefit, they have been proven effective in many reports. He remains open minded about alternative therapies such as biologicals but remains skeptical that they will replace steroids as the first-line therapy for active, moderate-to-severe TAO without head-to-head comparative clinical trials demonstrating superiority. Despite these very different points of view, both authors are optimistic about the availability of improved medical therapies for TAO, either as single agents or in combination. Further, both agree that better treatment options are needed to improve the care of our patients with active moderate-to-severe TAO.
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Affiliation(s)
- Terry J. Smith
- Department of Ophthalmology and Visual Sciences, Division of metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Luigi Bartalena
- Department of Medicine & Surgery,University of Insubria, Endocrine Unit, ASST dei Sette Laghi, Viale Borri, 57, 21100 Varese, Italy
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7
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Smith TJ. Challenges in Orphan Drug Development: Identification of Effective Therapy for Thyroid-Associated Ophthalmopathy. Annu Rev Pharmacol Toxicol 2018; 59:129-148. [PMID: 30044728 DOI: 10.1146/annurev-pharmtox-010617-052509] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Thyroid-associated ophthalmopathy (TAO), the ocular manifestation of Graves' disease, is a process in which orbital connective tissues and extraocular muscles undergo inflammation and remodeling. The condition seems to result from autoimmune responses to antigens shared by the thyroid and orbit. The thyrotropin receptor (TSHR), expressed at low levels in orbital tissues, is a leading candidate antigen. Recent evidence suggests that another protein, the insulin-like growth factor-I receptor (IGF-IR), is overexpressed in TAO, and antibodies against IGF-IR have been detected in patients with the disease. Furthermore, TSHR and IGF-IR form a physical and functional complex, and signaling initiated at TSHR requires IGF-IR activity. Identification of therapy for this rare disease has proven challenging and currently relies on nonspecific and inadequate agents, thus representing an important unmet need. A recently completed therapeutic trial suggests that inhibiting IGF-IR activity with a monoclonal antibody may be an effective and safe treatment for active TAO.
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Affiliation(s)
- Terry J Smith
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, and Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48105, USA;
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8
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Chen CR, McLachlan SM, Hubbard PA, McNally R, Murali R, Rapoport B. Structure of a Thyrotropin Receptor Monoclonal Antibody Variable Region Provides Insight into Potential Mechanisms for its Inverse Agonist Activity. Thyroid 2018; 28:933-940. [PMID: 29845889 PMCID: PMC6043401 DOI: 10.1089/thy.2018.0176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND The high constitutive, or ligand-independent, activity of the thyrotropin receptor (TSHR) is of clinical importance in some thyroid conditions, particularly well-differentiated thyroid carcinoma remnants following incomplete ablative therapy (surgery and radioiodine). Under these conditions, even total suppression of TSH by thyroid hormone administration does not fully reduce TSHR activity, a driver of thyrocyte growth. METHODS CS-17 is a murine monoclonal antibody that has inverse agonist activity in that it suppresses TSHR constitutive activity. This study crystallized the CS-17 Fab and determined its atomic structure at a resolution of 3.4 Å. RESULTS In silico docking of this structure to that of the TSHR extracellular domain was accomplished by targeting to TSHR residue tyrosine 195 (Y195) known to contribute to the CS-17 epitope. High affinity interaction between these two molecules, primarily by the CS-17 immunoglobulin heavy chain, was validated by energetic analysis (KD of 8.7 × 10-11 M), as well as by previously obtained data on a number of individual TSHR amino acids in three regions whose mutagenesis reduced CS-17 binding as detected by flow cytometry. CONCLUSIONS Structural insight at atomic resolution of a TSHR antibody with inverse agonist activity opens the way for the development of a molecule with therapeutic potential, particularly in thyroid carcinoma. For this purpose, CS-17 will require "humanization" by substitution of its constant region (Fc component). In addition, with its epitope defined, the CS-17 affinity can be increased further by mutagenesis of selected amino acids in its heavy- and light-chain complementarity determining regions.
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Affiliation(s)
- Chun-Rong Chen
- Thyroid Autoimmune Disease Unit, Department of Medicine, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, California
| | - Sandra M. McLachlan
- Thyroid Autoimmune Disease Unit, Department of Medicine, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, California
| | - Paul A. Hubbard
- Department of Biomedical Sciences, Research Division of Immunology, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, California
| | - Randall McNally
- Department of Biomedical Sciences, Research Division of Immunology, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, California
| | - Ramachandran Murali
- Department of Biomedical Sciences, Research Division of Immunology, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, California
| | - Basil Rapoport
- Thyroid Autoimmune Disease Unit, Department of Medicine, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, California
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Smith TJ. New advances in understanding thyroid-associated ophthalmopathy and the potential role for insulin-like growth factor-I receptor. F1000Res 2018; 7:134. [PMID: 29744034 PMCID: PMC5795270 DOI: 10.12688/f1000research.12787.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/24/2018] [Indexed: 01/15/2023] Open
Abstract
Thyroid-associated ophthalmopathy (TAO), a localized periocular manifestation of the autoimmune syndrome known as Graves’ disease, remains incompletely understood. Discussions of its pathogenesis are generally focused on the thyrotropin receptor, the proposed role for which is supported by substantial evidence. Considerations of any involvement of the insulin-like growth factor-I receptor (IGF-IR) in the disease are frequently contentious. In this brief, topically focused review, I have attempted to provide a balanced perspective based entirely on experimental results that either favor or refute involvement of IGF-IR in TAO. Discussion in this matter seems particularly timely since the currently available treatments of this disfiguring and potentially sight-threatening disease remain inadequate. Importantly, no medical therapy has thus far received approval from the US Food and Drug Administration. Results from a very recently published clinical trial assessing the safety and efficacy of teprotumumab, an inhibitory human anti–IGF-IR monoclonal antibody, in active, moderate to severe TAO are extremely encouraging. That double-masked, placebo-controlled study involved 88 patients and revealed unprecedented clinical responses in the improvement of proptosis and clinical activity as well as a favorable safety profile. Should those results prove reproducible in an ongoing phase III trial, therapeutic inhibition of IGF-IR could become the basis for paradigm-shifting treatment of this vexing disease.
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Affiliation(s)
- Terry J Smith
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center and Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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10
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Ulloa-Aguirre A, Zariñán T, Gutiérrez-Sagal R, Dias JA. Intracellular Trafficking of Gonadotropin Receptors in Health and Disease. Handb Exp Pharmacol 2018; 245:1-39. [PMID: 29063275 DOI: 10.1007/164_2017_49] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Gonadotropin receptors belong to the highly conserved subfamily of the G protein-coupled receptor (GPCR) superfamily, the so-called Rhodopsin-like family (class A), which is the largest class of GPCRs and currently a major drug target. Both the follicle-stimulating hormone receptor (FSHR) and the luteinizing hormone/chorionic gonadotropin hormone receptor (LHCGR) are mainly located in the gonads where they play key functions associated to essential reproductive functions. As any other protein, gonadotropin receptors must be properly folded into a mature tertiary conformation compatible with quaternary assembly and endoplasmic reticulum export to the cell surface plasma membrane. Several primary and secondary structural features, including presence of particular amino acid residues and short motifs and in addition, posttranslational modifications, regulate intracellular trafficking of gonadotropin receptors to the plasma membrane as well as internalization and recycling of the receptor back to the cell surface after activation by agonist. Inactivating mutations of gonadotropin receptors may derive from receptor misfolding and lead to absent or reduced plasma membrane expression of the altered receptor, thereby manifesting an array of phenotypical abnormalities mostly characterized by reproductive failure and/or abnormal or absence of development of secondary sex characteristics. In this chapter we review the structural requirements necessary for intracellular trafficking of the gonadotropin receptors, and describe how mutations in these receptors may lead to receptor misfolding and disease in humans.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Red de Apoyo a la Investigación (RAI), Universidad Nacional Autónoma de México-Instituto Nacional de Ciencias Médicas y Nutrición SZ, Vasco de Quiroga 15, Tlalpan, Mexico City, 14000, Mexico.
| | - Teresa Zariñán
- Red de Apoyo a la Investigación (RAI), Universidad Nacional Autónoma de México-Instituto Nacional de Ciencias Médicas y Nutrición SZ, Vasco de Quiroga 15, Tlalpan, Mexico City, 14000, Mexico
| | - Rubén Gutiérrez-Sagal
- Red de Apoyo a la Investigación (RAI), Universidad Nacional Autónoma de México-Instituto Nacional de Ciencias Médicas y Nutrición SZ, Vasco de Quiroga 15, Tlalpan, Mexico City, 14000, Mexico
| | - James A Dias
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, USA
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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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12
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Kleinau G, Kalveram L, Köhrle J, Szkudlinski M, Schomburg L, Biebermann H, Grüters-Kieslich A. Minireview: Insights Into the Structural and Molecular Consequences of the TSH-β Mutation C105Vfs114X. Mol Endocrinol 2016; 30:954-64. [PMID: 27387040 DOI: 10.1210/me.2016-1065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Naturally occurring thyrotropin (TSH) mutations are rare, which is also the case for the homologous heterodimeric glycoprotein hormones (GPHs) follitropin (FSH), lutropin (LH), and choriogonadotropin (CG). Patients with TSH-inactivating mutations present with central congenital hypothyroidism. Here, we summarize insights into the most frequent loss-of-function β-subunit of TSH mutation C105Vfs114X, which is associated with isolated TSH deficiency. This review will address the following question. What is currently known on the molecular background of this TSH variant on a protein level? It has not yet been clarified how C105Vfs114X causes early symptoms in affected patients, which are comparably severe to those observed in newborns lacking any functional thyroid tissue (athyreosis). To better understand the mechanisms of this mutant, we have summarized published reports and complemented this information with a structural perspective on GPHs. By including the ancestral TSH receptor agonist thyrostimulin and pathogenic mutations reported for FSH, LH, and choriogonadotropin in the analysis, insightful structure function and evolutionary restrictions become apparent. However, comparisons of immunogenicity and bioactivity of different GPH variants is hindered by a lack of consensus for functional analysis and the diversity of used GPH assays. Accordingly, relevant gaps of knowledge concerning details of GPH mutation-related effects are identified and highlighted in this review. These issues are of general importance as several previous and recent studies point towards the high impact of GPH variants in differential signaling regulation at GPH receptors (GPHRs), both endogenously and under diseased conditions. Further improvement in this area is of decisive importance for the development of novel targeted therapies.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Laura Kalveram
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Josef Köhrle
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Mariusz Szkudlinski
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Lutz Schomburg
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Annette Grüters-Kieslich
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
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13
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Nishihara E, Fukata S, Hishinuma A, Amino N, Miyauchi A. Prevalence of thyrotropin receptor germline mutations and clinical courses in 89 hyperthyroid patients with diffuse goiter and negative anti-thyrotropin receptor antibodies. Thyroid 2014; 24:789-95. [PMID: 24279482 DOI: 10.1089/thy.2013.0431] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND We studied the frequency of thyrotropin (TSH) receptor mutations in hyperthyroid patients with diffuse goiter and negative TSH receptor antibodies (TRAb), and the clinical pictures of the hyperthyroid patients in the presence and absence of mutations. PATIENTS AND METHODS From 2003 through 2012, 89 hyperthyroid patients with diffuse goiter and negative TRAb based on a second- or third-generation assay underwent sequence analysis of the TSH receptor gene from peripheral leukocytes. The outcome of hyperthyroidism in patients with a TSH receptor mutation and their affected family members was compared with that in patients without any mutation after a 1-10-year follow-up. RESULTS Germline mutations of the TSH receptor occurred in 4 of the 89 patients (4.5%), including 3 definitive constitutively activating mutations (L512Q, E575K, and D617Y). The main difference in the clinical outcome of hyperthyroidism was that no patients with a TSH receptor mutation achieved euthyroidism throughout the follow-up, while 23.5% of patients without any mutation entered remission. The progression from subclinical to overt hyperthyroidism was not significantly different between patients with or without a mutation. Meanwhile, 10.3% of TRAb-negative patients without any TSH receptor mutation developed TRAb-positive Graves' hyperthyroidism during the follow-up. CONCLUSIONS The prevalence of nonautoimmune hyperthyroidism with TSH receptor mutations is lower than that of latent Graves' disease in TRAb-negative patients with hyperthyroidism. However, all affected patients with a TSH receptor mutation showed persistent hyperthyroidism regardless of subclinical or overt hyperthyroidism throughout the follow-up.
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Affiliation(s)
- Eijun Nishihara
- 1 Center for Excellence in Thyroid Care, Kuma Hospital , Kobe, Japan
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14
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Kleinau G, Biebermann H. Constitutive activities in the thyrotropin receptor: regulation and significance. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 70:81-119. [PMID: 24931193 DOI: 10.1016/b978-0-12-417197-8.00003-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The thyroid-stimulating hormone receptor (TSHR, or thyrotropin receptor) is a family A G protein-coupled receptor. It not only binds thyroid-stimulating hormone (TSH, or thyrotropin) but also interacts with autoantibodies under pathological conditions. The TSHR and TSH are essential for thyroid growth and function and thus for all thyroid hormone-associated physiological superordinated processes, including metabolism and development of the central nervous system. In vitro studies have found that the TSHR permanently stimulates ligand-independent (constitutive) activation of Gs, which ultimately leads to intracellular cAMP accumulation. Furthermore, a vast variety of constitutively activating mutations of TSHR-at more than 50 different amino acid positions-have been reported to enhance basal signaling. These lead in vivo to a "gain-of-function" phenotype of nonautoimmune hyperthyroidism or toxic adenomas. Moreover, many naturally occurring inactivating mutations are known to cause a "loss-of-function" phenotype, resulting in resistance to thyroid hormone or hyperthyrotropinemia. Several of these mutations are also characterized by impaired basal signaling, and these are designated here as "constitutively inactivating mutations" (CIMs). More than 30 amino acid positions with CIMs have been identified so far. Moreover, the permanent TSHR signaling capacity can also be blocked by inverse agonistic antibodies or small drug-like molecules, which both have a potential for clinical usage. In this chapter, information on constitutive activity in the TSHR is described, including up- and downregulation, linked protein conformations, physiological and pathophysiological conditions, and related intracellular signaling.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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15
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Gupta MK, Misra K. Modeling and simulation analysis of propyl-thiouracil (PTU), an anti-thyroid drug on thyroid peroxidase (TPO), thyroid stimulating hormone receptor (TSHR), and sodium iodide (NIS) symporter based on systems biology approach. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s13721-013-0023-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Zoenen M, Urizar E, Swillens S, Vassart G, Costagliola S. Evidence for activity-regulated hormone-binding cooperativity across glycoprotein hormone receptor homomers. Nat Commun 2012; 3:1007. [DOI: 10.1038/ncomms1991] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 07/06/2012] [Indexed: 11/09/2022] Open
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17
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Chen CR, Salazar LM, McLachlan SM, Rapoport B. Novel information on the epitope of an inverse agonist monoclonal antibody provides insight into the structure of the TSH receptor. PLoS One 2012; 7:e31973. [PMID: 22359649 PMCID: PMC3281106 DOI: 10.1371/journal.pone.0031973] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 01/16/2012] [Indexed: 11/24/2022] Open
Abstract
The TSH receptor (TSHR) comprises an extracellular leucine-rich domain (LRD) linked by a hinge region to the transmembrane domain (TMD). Insight into the orientation of these components to each other is required for understanding how ligands activate the receptor. We previously identified residue E251 at the LRD-hinge junction as contributing to coupling TSH binding with receptor activation. However, a single residue cannot stabilize the LRD-hinge unit. Therefore, based on the LRD crystal structure we selected for study four other potential LRD-hinge interface charged residues. Alanine substitutions of individual residues K244, E247, K250 and R255 (as well as previously known E251A) did not affect TSH binding or function. However, the cumulative mutation of these residues in varying permutations, primarily K250A and R255A when associated with E251A, partially uncoupled TSH binding and function. These data suggest that these three residues, spatially very close to each other at the LRD base, interact with the hinge region. Unexpectedly and most important, monoclonal antibody CS-17, a TSHR inverse agonist whose epitope straddles the LRD-hinge, was found to interact with residues K244 and E247 at the base of the convex LRD surface. These observations, together with the functional data, exclude residues K244 and E247 from the TSHR LRD-hinge interface. Further, for CS-17 accessibility to K244 and E247, the concave surface of the TSHR LRD must be tilted forwards towards the hinge region and plasma membrane. Overall, these data provide insight into the mechanism by which ligands either activate the TSHR or suppress its constitutive activity.
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Affiliation(s)
- Chun-Rong Chen
- Thyroid Autoimmune Disease Unit, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
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18
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Hamidi S, Chen CR, McLachlan SM, Rapoport B. Insight into thyroid-stimulating autoantibody interaction with the thyrotropin receptor N-terminus based on mutagenesis and re-evaluation of ambiguity in this region of the receptor crystal structure. Thyroid 2011; 21:1013-20. [PMID: 21834684 PMCID: PMC3162645 DOI: 10.1089/thy.2011.0147] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Thyroid-stimulating autoantibodies (TSAb) bind to the thyrotropin receptor (TSHR) extracellular domain, or ectodomain (ECD), comprising a leucine-rich repeat domain (LRD) linked by a hinge region to the transmembrane domain (TMD). The LRD (residues 22-260; signal peptide 1-21) contains two disulfide-bonded loops at its N-terminus. In the crystal structure of the isolated LRD complexed with human TSAb monoclonal antibody (mAb) M22, N-terminal disulfide loop 1 (residues 22-30) could not be determined because of crystal disorder. Nevertheless, present crystal structure data are interpreted to exclude a role for the LRD N-terminal disulfide loops in the TSAb epitope(s), contradicting prior functional evidence of a role for these loops in TSAb function. MATERIALS AND METHODS To re-examine this issue we studied two cell types expressing the TSHR with the extreme N-terminal loop 1 (residues 22-30) deleted: the TSHR ECD lacking the TMD and tethered to the plasma membrane by a glycosyl-phosphatidylinositol (GPI) anchor, and the TSH holoreceptor containing the TMD. Because TSAb including M22 "see" the holoreceptor poorly relative to the TSHR ECD-GPI, we used the latter to examine the effect of deleting residues 22-30 on M22 binding by flow cytometry and the holoreceptor to test the effect of this deletion on the functional response to M22. RESULTS Deletion of TSHR N-terminal loop 1 (residues 22-30) reduced the number of TSHR-ECD-GPI recognized by M22 relative to two TSHR mAb with epitopes far downstream of the LRD N-terminal loops. Relative to control mAb 2C11, M22 recognized only 60.4% of cell surface receptors (p = 0.02). In contrast to M22 binding to TSHR-ECD-GPI, in functional studies with the TSH holoreceptor, M22 stimulation of cAMP generation was unaltered by the loop 1 deletion. CONCLUSIONS Our data support the concept that TSAb interact with the cysteine-rich N-terminus of the TSHR. Comparison of crystal structures of the same TSHR LRD in complex with TSAb M22 or blocking antibody K1-70 helps reconcile contradictory viewpoints. A difference between M22 interaction with the identical TSHR N-terminus expressed on the TSHR-ECD-GPI and holoreceptor suggests that crystallization of the TSHR LRD-M22 complex may not provide a complete understanding of the functional TSAb epitope(s) in Graves' disease.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/metabolism
- Binding Sites, Antibody
- CHO Cells
- Cricetinae
- Cricetulus
- Crystallography
- Epitope Mapping
- Epitopes
- Flow Cytometry
- Immunoglobulins, Thyroid-Stimulating/chemistry
- Immunoglobulins, Thyroid-Stimulating/metabolism
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Interaction Domains and Motifs
- Receptors, Thyrotropin/chemistry
- Receptors, Thyrotropin/genetics
- Receptors, Thyrotropin/metabolism
- Structure-Activity Relationship
- Transfection
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Affiliation(s)
- Sepehr Hamidi
- Thyroid Autoimmune Disease Unit, Cedars-Sinai Research Institute, Los Angeles, California
- School of Medicine, University of California—Los Angeles, Los Angeles, California
| | - Chun-Rong Chen
- Thyroid Autoimmune Disease Unit, Cedars-Sinai Research Institute, Los Angeles, California
- School of Medicine, University of California—Los Angeles, Los Angeles, California
| | - Sandra M. McLachlan
- Thyroid Autoimmune Disease Unit, Cedars-Sinai Research Institute, Los Angeles, California
- School of Medicine, University of California—Los Angeles, Los Angeles, California
| | - Basil Rapoport
- Thyroid Autoimmune Disease Unit, Cedars-Sinai Research Institute, Los Angeles, California
- School of Medicine, University of California—Los Angeles, Los Angeles, California
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19
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Kleinau G, Mueller S, Jaeschke H, Grzesik P, Neumann S, Diehl A, Paschke R, Krause G. Defining structural and functional dimensions of the extracellular thyrotropin receptor region. J Biol Chem 2011; 286:22622-31. [PMID: 21525003 DOI: 10.1074/jbc.m110.211193] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The extracellular region of the thyrotropin receptor (TSHR) can be subdivided into the leucine-rich repeat domain (LRRD) and the hinge region. Both the LRRD and the hinge region interact with thyrotropin (TSH) or autoantibodies. Structural data for the TSHR LRRD were previously determined by crystallization (amino acids Glu(30)-Thr(257), 10 repeats), but the structure of the hinge region is still undefined. Of note, the amino acid sequence (Trp(258)-Tyr(279)) following the crystallized LRRD comprises a pattern typical for leucine-rich repeats with conserved hydrophobic side chains stabilizing the repeat fold. Moreover, functional data for amino acids between the LRRD and the transmembrane domain were fragmentary. We therefore investigated systematically these TSHR regions by mutagenesis to reveal insights into their functional contribution and potential structural features. We found that mutations of conserved hydrophobic residues between Thr(257) and Tyr(279) cause TSHR misfold, which supports a structural fold of this peptide, probably as an additional leucine-rich repeat. Furthermore, we identified several new mutations of hydrophilic amino acids in the entire hinge region leading to partial TSHR inactivation, indicating that these positions are important for intramolecular signal transduction. In summary, we provide new information regarding the structural features and functionalities of extracellular TSHR regions. Based on these insights and in context with previous results, we suggest an extracellular activation mechanism that supports an intramolecular agonistic unit as a central switch for activating effects at the extracellular region toward the serpentine domain.
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Affiliation(s)
- Gunnar Kleinau
- Department for Structural Biology, Leibniz-Institut für Molekulare Pharmakologie, D-13125 Berlin, Germany
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20
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Neumann S, Huang W, Eliseeva E, Titus S, Thomas CJ, Gershengorn MC. A small molecule inverse agonist for the human thyroid-stimulating hormone receptor. Endocrinology 2010; 151:3454-9. [PMID: 20427476 PMCID: PMC2903937 DOI: 10.1210/en.2010-0199] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Small molecule inverse agonists for the TSH receptor (TSHR) may be used as probes of the role of basal (or agonist-independent or constitutive) signaling and may have therapeutic potential as orally active drugs to inhibit basal signaling in patients with thyroid cancer and in some patients with hyperthyroidism. We describe the first small-molecule ligand [1;2-(3-((2,6-dimethylphenoxy)methyl)-4-methoxyphenyl)-3-(furan-2-ylmethyl)-2,3-dihydroquinazolin-4(1H)-one] that exhibits inverse agonist properties at TSHR. 1 inhibits basal and TSH-stimulated signaling, measured as cAMP production, by TSHRs in HEK-EM 293 cells stably expressing wild-type TSHRs; the antagonism of TSH-mediated signaling is competitive. 1 also inhibits basal signaling by wild-type TSHRs, and four constitutively active mutants of TSHR expressed transiently in HEK-EM 293 cells. 1 was active under more physiologically relevant conditions in primary cultures of human thyrocytes expressing endogenous TSHRs where it inhibited basal levels of mRNA transcripts for thyroglobulin, thyroperoxidase, sodium iodide symporter, and TSHR. These data serve as proof of principle that small, drug-like molecules can inhibit basal signaling by TSHR. We suggest that this small molecule is a lead compound for the development of higher-potency inverse agonists that can be used as probes of TSHR biology with therapeutic potential.
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Affiliation(s)
- Susanne Neumann
- National Institute of Diabetes and Digestive and Kidney Diseases, Clinical Endocrinology Branch, National Institutes of Health, 50 South Drive, Bethesda, Maryland 20892-8029
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21
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Chen CR, McLachlan SM, Rapoport B. Thyrotropin (TSH) receptor residue E251 in the extracellular leucine-rich repeat domain is critical for linking TSH binding to receptor activation. Endocrinology 2010; 151:1940-7. [PMID: 20181794 PMCID: PMC2851189 DOI: 10.1210/en.2009-1430] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The TSH receptor (TSHR) ectodomain comprises a tubular leucine-rich repeat domain (LRD) and a hinge [or signaling specificity domain (SSD)]. TSH binds to both the LRD and SSD, leading to signal transduction by the transmembrane domain. The SSD structure and spatial orientation to the other components are unknown. We exploited a fortuitous observation to obtain mechanistic insight into the relationship between TSH binding and signal transduction. A mouse TSHR cDNA generated by PCR was found to express a receptor with poor TSH-induced cAMP generation despite normal TSH binding. Progressive reversion to wild-type of six mutations revealed E251K in the LRD to be critical for reduced signal transduction in both mouse and human TSHR. An I286F substitution in the SSD had a much weaker effect and was additive with E251K. To our knowledge, there are no previous examples of specific amino acid mutations in the TSHR LRD that dissociate TSH binding from TSHR signal transduction. To prevent flailing of the TSHR LRD, its position vis-à-vis the SSD must be stabilized by multiple amino acid interactions. The present data suggest that TSHR residue E251 is one of these residues involved in stabilizing the LRD relative to the SSD, thereby enabling ligand binding to transduce a signal by the latter. That the E251K mutation can reduce signal transduction despite high-affinity TSH binding comparable with the wild-type TSHR provides mechanistic insight into the coupling between ligand binding and receptor activation.
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Affiliation(s)
- Chun-Rong Chen
- Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Suite B-131, Los Angeles, California 90048.
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22
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Mueller S, Jaeschke H, Günther R, Paschke R. The hinge region: an important receptor component for GPHR function. Trends Endocrinol Metab 2010; 21:111-22. [PMID: 19819720 DOI: 10.1016/j.tem.2009.09.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 09/11/2009] [Accepted: 09/11/2009] [Indexed: 11/24/2022]
Abstract
Glycoprotein hormone receptors (GPHRs) are members of the seven-transmembrane-spanning receptor family characterized by a large ectodomain. The hinge region belongs to a part of the GPHR ectodomain for which the three-dimensional structure has not yet been deciphered, leaving important questions unanswered concerning ligand binding and GPHR activation. Recent publications indicate that specific residues of the hinge region mediate hormone binding, receptor activation and/or intramolecular signaling for the three GPHRs, emphasizing the importance of this region. Based on these findings, the hinge region is involved at least in part in hormone binding and receptor activation. This review summarizes functional data regarding the hinge region, demonstrating that this receptor portion represents a link between ligand binding and subsequent GPHR activation.
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MESH Headings
- Amino Acid Sequence
- Humans
- Models, Biological
- Molecular Sequence Data
- Protein Folding
- Protein Structure, Tertiary/physiology
- Receptors, FSH/chemistry
- Receptors, FSH/physiology
- Receptors, LH/chemistry
- Receptors, LH/physiology
- Receptors, Pituitary Hormone/chemistry
- Receptors, Pituitary Hormone/immunology
- Receptors, Pituitary Hormone/physiology
- Receptors, Thyrotropin/chemistry
- Receptors, Thyrotropin/immunology
- Receptors, Thyrotropin/physiology
- Sequence Homology, Amino Acid
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Affiliation(s)
- Sandra Mueller
- Third Medical Department, University of Leipzig, Liebigstrasse 20, 04103 Leipzig, Germany
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23
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Neumann S, Raaka BM, Gershengorn MC. Human TSH receptor ligands as pharmacological probes with potential clinical application. Expert Rev Endocrinol Metab 2009; 4:669. [PMID: 20161662 PMCID: PMC2819035 DOI: 10.1586/eem.09.36] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The biologic role of thyroid-stimulating hormone (TSH; thyrotropin) as an activator (agonist) of the TSH receptor (TSHR) in the hypothalamic-pituitary-thyroid axis is well known and activation of TSHR by recombinant human TSH is used clinically in patients with thyroid cancer. TSHR ligands other than TSH could be used to probe TSHR biology in thyroidal and extrathyroidal tissues, and potentially be employed in patients. A number of different TSHR ligands have been reported, including TSH analogs, antibodies and small-molecule, drug-like compounds. In this review, we will provide an update on all these classes of TSHR agonists and antagonists but place emphasis on small-molecule ligands.
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Affiliation(s)
- Susanne Neumann
- Clinical Endocrinology Branch, NIDDK, NIH, 50 South Drive, Bethesda, MD 20892-28029, USA, Tel.: +1 301 451 6324, Fax: +1 301 480 4214
| | - Bruce M Raaka
- Clinical Endocrinology Branch, NIDDK, NIH, 50 South Drive, Bethesda, MD 20892-28029, USA, Tel.: +1 301 451 6307, Fax: +1 301 480 4214
| | - Marvin C Gershengorn
- Author for correspondence: Clinical Endocrinology Branch, NIDDK, NIH, 50 South Drive, Bethesda, MD 20892-28029, USA, Tel.: +1 301 451 6305, Fax: +1 301 480 4214,
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