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Mezei M, Baliram R, Ali MR, Zaidi M, Davies TF, Latif R. The Human TSHβ Subunit Proteins and Their Binding Sites on the TSH Receptor Using Molecular Dynamics Simulation. Endocrinology 2020; 161:5879754. [PMID: 32738139 PMCID: PMC7447003 DOI: 10.1210/endocr/bqaa125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/30/2020] [Indexed: 12/18/2022]
Abstract
To gain further insight into the binding of the normal and variant human TSHβ subunits (TSHβ and TSHβv), we modeled the 2 monomeric proteins and studied their interaction with the TSH receptor ectodomain (TSHR-ECD) using molecular dynamics simulation Furthermore, analyzed their bioactivity in vitro using recombinant proteins to confirm that such binding was physiologically relevant. Examining the interaction of TSHβ and TSHβv with the TSHR-ECD model using molecular dynamic simulation revealed strong binding of these proteins to the receptor ECD. The specificity of TSHβ and TSHβv binding to the TSHR-ECD was examined by analyzing the hydrogen-bonding residues of these subunits to the FSH receptor ECD, indicating the inability of these molecules to bind to the FSH receptors. Furthermore, the modelling suggests that TSHβ and TSHβv proteins clasped the concave surface of the leucine rich region of the TSHR ECD in a similar way to the native TSH using dynamic hydrogen bonding. These mutually exclusive stable interactions between the subunits and ECD residues included some high-affinity contact sites corresponding to binding models of native TSH. Furthermore, we cloned TSHβ and TSHβv proteins using the entire coding ORF and purified the flag-tagged proteins. The expressed TSHβ subunit proteins retained bioactivity both in a coculture system as well as with immune-purified proteins. In summary, we showed that such interactions can result in a functional outcome and may exert physiological or pathophysiological effects in immune cells.
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Affiliation(s)
- Mihaly Mezei
- Department of Pharmacological Sciences, New York, New York
- Correspondence: Mihaly Mezei, Department of Pharmacological Sciences, Icahn school of Medicine, Ine Gustave L Levy PL, New York NY 10029. E-mail:
| | - Ramkumarie Baliram
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
- James J. Peters VA Medical Center, New York, New York
| | - M Rejwan Ali
- Department of Pharmacological Sciences, New York, New York
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Mone Zaidi
- Mount Sinai Bone Program, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Terry F Davies
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
- James J. Peters VA Medical Center, New York, New York
| | - Rauf Latif
- Thyroid Research Unit, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
- James J. Peters VA Medical Center, New York, New York
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Abstract
An insufficient stimulation by thyrotropin (TSH) of an otherwise normal thyroid gland represents the cause of Central Hypothyrodism (CeH). CeH is about 1000-folds rarer than Primary Hypothyroidism and often represents a real challenge for the clinicians, mainly because they cannot rely on adequately sensitive parameters for diagnosis or management, as it occurs with circulating TSH in PH. Therefore, CeH diagnosis can be frequently missed or delayed in patients with a previously unknown pituitary involvement. A series of genetic defects have been described to account for isolated CeH or combined pituitary hormone defects (CPHDs) with variable clinical characteristics and degrees of severity. The recently identified candidate gene IGSF1 appears frequently involved. This review provides an updated illustration of the different genetic defects accounting for CeH.
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Affiliation(s)
- Luca Persani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy; Division of Endocrine and Metabolic Diseases, San Luca Hospital, Istituto Auxologico Italiano, Milan, Italy.
| | - Marco Bonomi
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy; Division of Endocrine and Metabolic Diseases, San Luca Hospital, Istituto Auxologico Italiano, Milan, Italy
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Li H, Zhu H, Qin Q, Lei M, Shi Z. Production of biologically active recombinant goose FSH in a single chain form with a CTP linker sequence. Mol Biol Rep 2016; 44:11-17. [PMID: 27909922 DOI: 10.1007/s11033-016-4093-9] [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: 03/24/2016] [Accepted: 11/24/2016] [Indexed: 10/20/2022]
Abstract
FSH is a glycoprotein hormone secreted by the pituitary gland that is essential for gonadal development and reproductive function. In avian reproduction study, especially in avian reproduction hormone study, it is hindered by the lack of biologically active FSH. In order to overcome this shortcoming, we prepared recombinant goose FSH as a single chain molecule and tested its biological activities in the present study. Coding sequences for mature peptides of goose FSH α and β subunits were amplified from goose pituitary cDNA. A chimeric gene containing α and β subunit sequences linked by the hCG carboxyl terminal peptide coding sequence was constructed. The recombinant gene was inserted into the pcDNA3.1-Fc eukaryotic expression vector to form pcDNA-Fc-gFSHβ-CTP-α and then transfected into 293-F cells. A recombinant, single chain goose FSH was expressed and verified by SDS-PAGE and western blot analysis, and was purified using Protein A agarose affinity and gel filtration chromatography. Biological activity analysis results showed that the recombinant, chimeric goose FSH possesses the function of stimulating estradiol secretion and cell proliferation, in cultured chicken granulosa cells. These results indicated that bioactive, recombinant goose FSH has been successfully prepared in vitro. The recombinant goose FSH will have the potential of being used as a research tool for studying avian reproductive activities, and as a standard for developing avian FSH bioassays.
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Affiliation(s)
- Hui Li
- Key laboratory of Animal Breeding and Reproduction, Institute of Animal Science in Jiangsu Academy of Agricultural Science, Nanjing, 210014, China
| | - Huanxi Zhu
- Key laboratory of Animal Breeding and Reproduction, Institute of Animal Science in Jiangsu Academy of Agricultural Science, Nanjing, 210014, China
| | - Qinming Qin
- College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Mingming Lei
- Key laboratory of Animal Breeding and Reproduction, Institute of Animal Science in Jiangsu Academy of Agricultural Science, Nanjing, 210014, China
| | - Zhendan Shi
- Key laboratory of Animal Breeding and Reproduction, Institute of Animal Science in Jiangsu Academy of Agricultural Science, Nanjing, 210014, China.
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Kleinau G, Neumann S, Grüters A, Krude H, Biebermann H. Novel insights on thyroid-stimulating hormone receptor signal transduction. Endocr Rev 2013; 34:691-724. [PMID: 23645907 PMCID: PMC3785642 DOI: 10.1210/er.2012-1072] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The TSH receptor (TSHR) is a member of the glycoprotein hormone receptors, a subfamily of family A G protein-coupled receptors. The TSHR is of great importance for the growth and function of the thyroid gland. The TSHR and its endogenous ligand TSH are pivotal proteins with respect to a variety of physiological functions and malfunctions. The molecular events of TSHR regulation can be summarized as a process of signal transduction, including signal reception, conversion, and amplification. The steps during signal transduction from the extra- to the intracellular sites of the cell are not yet comprehensively understood. However, essential new insights have been achieved in recent years on the interrelated mechanisms at the extracellular region, the transmembrane domain, and intracellular components. This review contains a critical summary of available knowledge of the molecular mechanisms of signal transduction at the TSHR, for example, the key amino acids involved in hormone binding or in the structural conformational changes that lead to G protein activation or signaling regulation. Aspects of TSHR oligomerization, signaling promiscuity, signaling selectivity, phenotypes of genetic variations, and potential extrathyroidal receptor activity are also considered, because these are relevant to an understanding of the overall function of the TSHR, including physiological, pathophysiological, and pharmacological perspectives. Directions for future research are discussed.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Ostring 3, Augustenburger Platz 1, 13353 Berlin, Germany.
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Krause G, Kreuchwig A, Kleinau G. Extended and structurally supported insights into extracellular hormone binding, signal transduction and organization of the thyrotropin receptor. PLoS One 2012; 7:e52920. [PMID: 23300822 PMCID: PMC3531376 DOI: 10.1371/journal.pone.0052920] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 11/23/2012] [Indexed: 11/18/2022] Open
Abstract
The hormone thyrotropin (TSH) and its receptor (TSHR) are crucial for the growth and function of the thyroid gland. The TSHR is evolutionary linked with the receptors of follitropin (FSHR) and lutropin/choriogonadotropin (LHR) and their sequences and structures are similar. The extracellular region of TSHR contains more than 350 amino acids and binds hormone and antibodies. Several important questions related to functions and mechanisms of TSHR are still not comprehensively understood. One major reason for these open questions is the lack of any structural information about the extracellular segment of TSHR that connects the N-terminal leucine-rich repeat domain (LRRD) with the transmembrane helix (TMH) 1, the hinge region. It has been shown experimentally that this segment is important for fine tuning of signaling and ligand interactions. A new crystal structure containing most of the extracellular hFSHR region in complex with hFSH has recently been published. Now, we have applied these new structural insights to the homologous TSHR and have generated a structural model of the TSHR LRRD/hinge-region/TSH complex. This structural model is combined and evaluated with experimental data including hormone binding (bTSH, hTSH, thyrostimulin), super-agonistic effects, antibody interactions and signaling regulation. These studies and consideration of significant and non-significant amino acids have led to a new description of mechanisms at the TSHR, including ligand-induced displacements of specific hinge region fragments. This event triggers conformational changes at a convergent center of the LRRD and the hinge region, activating an “intramolecular agonistic unit” close to the transmembrane domain.
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Affiliation(s)
- Gerd Krause
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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Liu C, Li L, Ying F, Xu C, Zang X, Gao Z. A newly identified TSHβ splice variant is involved in the pathology of Hashimoto's thyroiditis. Mol Biol Rep 2012; 39:10019-30. [PMID: 22752807 DOI: 10.1007/s11033-012-1871-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 06/20/2012] [Indexed: 11/26/2022]
Abstract
Thyrotropin (TSH) is a protein that plays a key role in the control of thyroid function. TSH consists of a common α-subunit and a unique β-subunit; the latter is responsible for hormone specificity. A novel splice variant of human TSHβ was identified in 2009. To date, only the tissue distribution of the human TSHβ splice variant mRNA has been studied. Therefore, we aimed to characterize the protein translated from this splice variant. Salting-out, dialysis and concentration of serum proteins were followed by immunoprecipitation to identify the hTSHβ splice variant in serum. Stable CHO cell lines expressing the hTSHβ splice variant and V5-hTSHα were generated. After co-culture, co-immunoprecipitation was used to determine if the hTSHβ splice variant can dimerise with TSHα. We showed for the first time that the hTSHβ splice variant exists in human serum and dimerises with TSHα. To explore the relationship between the TSHβ splice variant and the pathogenesis of autoimmune thyroiditis, we assessed variations in the mRNA expression of the TSHβ splice variant in the peripheral blood leukocytes (PBLs) of Hashimoto's thyroiditis (HT) patients using quantitative RT-PCR. We found that the mRNA expression levels of the TSHβ splice variant were higher in the PBLs of HT patients who were not undergoing prednisone therapy (n = 10, P < 0.0001) and in the PBLs of HT patients with a longer duration of illness (>18 months) who were undergoing prednisone therapy (n = 5, P = 0.023) than in those of the control group. This pattern was reversed in the PBLs of HT patients with a shorter duration of illness (<9 months) who were undergoing prednisone therapy (n = 8, P < 0.0001). Dexamethasone inhibition of the TSHβ splice variant mRNA expression occurred in a dose- and time-dependent manner. These results demonstrated that the TSHβ splice variant may participate in the pathogenesis of HT.
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Affiliation(s)
- Chunrong Liu
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, QiXiangTai Road No22, HePing District, Tianjin 300070, China
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Reinfelder J, Maschauer S, Foss CA, Nimmagadda S, Fremont V, Wolf V, Weintraub BD, Pomper MG, Szkudlinski MW, Kuwert T, Prante O. Effects of recombinant human thyroid-stimulating hormone superagonists on thyroidal uptake of 18F-fluorodeoxyglucose and radioiodide. Thyroid 2011; 21:783-92. [PMID: 21568725 DOI: 10.1089/thy.2010.0394] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Superagonist analogs of human thyroid-stimulating hormone (hTSH) may stimulate the uptake of (131)I-iodide and (18)F-fluorodeoxyglucose ((18)F-FDG) in thyroid carcinomas to a greater degree than hTSH. We herein report the potency and efficacy of two hTSH analogs, TR1401 and TR1402, to stimulate radioiodide and (18)F-FDG uptake in FRTL-5 cells and compared the effects of hTSH and TR1401 on radioiodide uptake in the thyroid in vivo in mice. METHODS The effects of hTSH analogs on intracellular levels of cAMP, uptake of (131)I-iodide, and (18)F-FDG were studied in FRTL-5 cells to determine the stimulatory potency and efficacy of the compounds by calculating half-maximum effective concentration (EC(50)) values and maximal stimulatory effects (E(max)). Biodistribution studies (n = 96) and positron emission tomography/computed tomography imaging studies (single animals) on thyroid (125)I/(124)I-iodide uptake were performed with T3-suppressed CD-1 mice in a dose-dependent manner (3, 10, and 30 μg/animal). RESULTS The EC(50) values of TR1401 and TR1402 demonstrated a 90-fold or 800-fold higher potency for their capacity to increase intracellular cAMP levels in comparison with hTSH (p < 0.05). Similar results were demonstrated for the stimulation of (18)F-FDG uptake. Bovine TSH, TR1401, and TR1402 were 85%-490% more potent to increase iodide uptake than hTSH (p < 0.05). TR1402 was 30% more efficacious to stimulate iodide uptake than hTSH. The agonist-induced increase in radiotracer uptake was paralleled by increases in NIS and GLUT-1 expression. Ex vivo biodistribution studies showed an increased iodide uptake in the thyroid of TR1401-treated mice at the low dose of 3 μg/animal in comparison with hTSH-treated mice (n = 16, p < 0.05). Positron emission tomography/computed tomography imaging studies confirmed the increased thyroidal iodide uptake in TR1401-treated mice in vivo. CONCLUSIONS TR1401 and TR1402 have considerably higher potency than hTSH to stimulate thyroidal iodide and (18)F-FDG uptake in vitro. Moreover, in vivo studies indicated that at low but not higher doses, TR1401 induced an enhanced ability for the thyroid to concentrate iodide compared with hTSH. These properties makes TR1401 and TR1402 interesting candidates for use in humans to enhance uptake of radioiodine and (18)F-FDG by metastases and recurrences of thyroid carcinoma.
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Affiliation(s)
- Julia Reinfelder
- Laboratory of Molecular Imaging, Clinic of Nuclear Medicine, Friedrich-Alexander University, Erlangen, Germany
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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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Lysozyme retention on hydrophobic interaction chromatography predicts resin performance at large scale. Biotechnol Appl Biochem 2009; 54:157-62. [DOI: 10.1042/ba20090125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
In recent years, many new recombinant protein therapeutics have been developed and tested in clinical trials [1]. Current and future clinical uses of recombinant human thyroid-stimulating hormone (rhTSH; Thyrogen, Genzyme) in thyroid diseases are discussed in the review published in this issue of Expert Opinion on Pharmacotherapy [2]. As Thyrogen is a wild-type rhTSH produced in Chinese hamster ovary cells, it has relatively low affinity to the human TSH receptor. Such low affinity and weak intrinsic bioactivity of rhTSH, compared to the bovine or rodent TSH, may help to explain the results of several studies indicating limited clinical efficacy of Thyrogen. TSH analogues with largely increased receptor affinity, potency and efficacy, are expected to provide not only more effective than currently used diagnostic methods, but should also serve as indispensable second-generation thyrotropins for the diagnosis and treatment of thyroid carcinomas with a largely limited number of TSH receptors.
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Szkudlinski MW. Past, presence and future of thyroid-stimulating hormone (TSH) superactive analogs. Cancer Treat Res 2004; 122:345-56. [PMID: 16209054 DOI: 10.1007/1-4020-8107-3_19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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Szkudlinski MW, Fremont V, Ronin C, Weintraub BD. Thyroid-stimulating hormone and thyroid-stimulating hormone receptor structure-function relationships. Physiol Rev 2002; 82:473-502. [PMID: 11917095 DOI: 10.1152/physrev.00031.2001] [Citation(s) in RCA: 296] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review focuses on recent advances in the structure-function relationships of thyroid-stimulating hormone (TSH) and its receptor. TSH is a member of the glycoprotein hormone family constituting a subset of the cystine-knot growth factor superfamily. TSH is produced by the pituitary thyrotrophs and released to the circulation in a pulsatile manner. It stimulates thyroid functions using specific membrane TSH receptor (TSHR) that belongs to the superfamily of G protein-coupled receptors (GPCRs). New insights into the structure-function relationships of TSH permitted better understanding of the role of specific protein and carbohydrate domains in the synthesis, bioactivity, and clearance of this hormone. Recent progress in studies on TSHR as well as studies on the other GPCRs provided new clues regarding the molecular mechanisms of receptor activation. Such advances are a result of extensive site-directed mutagenesis, peptide and antibody approaches, detailed sequence analyses, and molecular modeling as well as studies on naturally occurring gain- and loss-of-function mutations. This review integrates expanding information on TSH and TSHR structure-function relationships and summarizes current concepts on ligand-dependent and -independent TSHR activation. Special emphasis has been placed on TSH domains involved in receptor recognition, constitutive activity of TSHR, new insights into the evolution of TSH bioactivity, and the development of high-affinity TSH analogs. Such structural, physiological, pathophysiological, evolutionary, and therapeutic implications of TSH-TSHR structure-function studies are frequently discussed in relation to concomitant progress made in studies on gonadotropins and their receptors.
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Affiliation(s)
- Mariusz W Szkudlinski
- Section of Protein Engineering, Laboratory of Molecular Endocrinology, Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland, USA.
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Fares FA, Levi F, Reznick AZ, Kraiem Z. Engineering a potential antagonist of human thyrotropin and thyroid-stimulating antibody. J Biol Chem 2001; 276:4543-8. [PMID: 11083869 DOI: 10.1074/jbc.m008093200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thyrotropin (TSH) and the gonadotropins (FSH, LH, hCG) are a family of heterodimeric glycoprotein hormones composed of two noncovalently linked subunits, alpha and beta. We have recently converted the hTSH heterodimer to a biologically active single chain (hTSHbeta.CTPalpha) by fusing the common alpha-subunit to the C-terminal end of the hTSH beta-subunit in the presence of a approximately 30-amino acid peptide from hCGbeta (CTP) as a linker. The hTSHbeta.CTPalpha single chain was used to investigate the role of the N-linked oligosaccharides of alpha- and beta-subunits in the secretion and function of hTSH. Using overlapping PCR mutagenesis, two deglycosylated variants were prepared: one lacking both oligosaccharide chains on the alpha-subunit (hTSHbeta.CTPalpha(1+2)) and the other lacking the oligosaccharide chain on the beta-subunit (hTSHbeta.CTPalpha(deg)). The single chain variants were expressed in CHO cells and were secreted into the medium. hTSH variants lacking the oligosaccharide chains were less potent than hTSHbeta.CTPalpha wild-type with respect to cAMP formation and thyroid hormone secretion in cultured human thyroid follicles. Both deglycosylated variants competed with hTSH in a dose-dependent manner. The hTSHbeta.CTPalpha(1+2) variant blocked cAMP formation and thyroid hormone secretion stimulated by hTSH as well as by the antibody, thyroid-stimulating immunoglobulins, responsible for the most common cause of hyperthyroidism, Graves disease. Thus, this variant behaves as a potential antagonist, offering a novel therapeutic strategy in the treatment of thyrotoxicosis caused by Graves' disease and TSH-secreting pituitary adenoma.
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Affiliation(s)
- F A Fares
- Department of Biochemistry, Carmel Medical Center and the Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 34362 Israel.
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Bioengineering of Human Thyrotropin Superactive Analogs by Site-directed “Lysine-scanning” Mutagenesis. J Biol Chem 2000. [DOI: 10.1016/s0021-9258(19)61530-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Szkudlinski MW, Grossmann M, Leitolf H, Weintraub BD. Human thyroid-stimulating hormone: structure-function analysis. Methods 2000; 21:67-81. [PMID: 10764608 DOI: 10.1006/meth.2000.0976] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This article provides the reader with an overview of methodological strategies to investigate structure-function relationships of human thyroid-stimulating hormone (hTSH). Various aspects of hTSH production, purification, and characterization described here in more detail are not only relevant to studies on other members of the glycoprotein hormone family, but also applicable to studies of other glycosylated proteins. Knowledge of structure-function relationships of specific hTSH domains is important for a better understanding of the molecular mechanisms of its action. New insights from such studies permit the design of glycoprotein hormone analogs with specific pharmacological properties and potential clinical applications.
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Affiliation(s)
- M W Szkudlinski
- Laboratory of Molecular Endocrinology, Department of Medicine, University of Maryland School of Medicine and the Institute of Human Virology, Medical Biotechnology Center, 725 West Lombard Street, Baltimore, Maryland 21201-1009, USA.
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Abstract
We have gained insight into the molecular mechanism of human thyrotropin (hTSH) action through cloning of the human TSHbeta subunit gene, development of recombinant TSH and novel analogues and chimeras produced by site-directed as well as cassette mutagenesis. A variety of loss of function mutations have shown several key domains in both the alpha- and beta-subunits that are important for high-affinity ligand interaction with the receptor. In contrast the specificity of receptor interaction was shown to be determined primarily by areas within the hTSH-beta "seat-belt" region. We have also designed various gain of function mutants (superagonists) using evolutionary considerations, homology modeling, and sequence comparisons within the cystine knot growth factor superfamily. Such superagonists resulted from increasing the positive charge by introduction of lysine or arginine residues or neutralization of negatively charged residues of the peripheral hairpin loops of each subunit in various combinations. Certain superagonists increased receptor binding, in vitro and in vivo bioactivity 100- to 1000-fold, more than that achieved previously for any other known protein ligand. In vivo metabolic clearance and biologic activity could be separately modulated by alteration of TSH carbohydrate structure including production of chimeras that added sites of O-glycosylation and/or covalently linked the alpha- and beta-subunits. These data suggest that electrostatic interactions resulting from net positive charge in TSH and net negative charge in its receptor play an important role in high-affinity TSH receptor binding and signal transduction. Insights gained from the design of such novel recombinant TSH analogues and chimeras should have many diagnostic and therapeutic applications. These include the design of improved in vitro assays for thyrotropic factors as well as the design of second generation recombinant TSH analogues for the detection and treatment of thyroid cancer.
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Affiliation(s)
- B D Weintraub
- Department of Medicine, University of Maryland School of Medicine and the Institute of Human Virology, Medical Biotechnology Center, Baltimore 21201-1068, USA
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Bhatia PK, Mukhopadhyay A. Protein glycosylation: implications for in vivo functions and therapeutic applications. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1999; 64:155-201. [PMID: 9933978 DOI: 10.1007/3-540-49811-7_5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The glycosylation machinery in eukaryotic cells is available to all proteins that enter the secretory pathway. There is a growing interest in diseases caused by defective glycosylation, and in therapeutic glycoproteins produced through recombinant DNA technology route. The choice of a bioprocess for commercial production of recombinant glycoprotein is determined by a variety of factors, such as intrinsic biological properties of the protein being expressed and the purpose for which it is intended, and also the economic target. This review summarizes recent development and understanding related to synthesis of glycans, their functions, diseases, and various expression systems and characterization of glycans. The second section covers processing of N- and O-glycans and the factors that regulate protein glycosylation. The third section deals with in vivo functions of protein glycosylation, which includes protein folding and stability, receptor functioning, cell adhesion and signal transduction. Malfunctioning of glycosylation machinery and the resultant diseases are the subject of the fourth section. The next section covers the various expression systems exploited for the glycoproteins: it includes yeasts, mammalian cells, insect cells, plants and an amoeboid organism. Biopharmaceutical properties of therapeutic proteins are discussed in the sixth section. In vitro protein glycosylation and the characterization of glycan structures are the subject matters for the last two sections, respectively.
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Affiliation(s)
- P K Bhatia
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
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Abstract
Hypothalamic thyrotropin-releasing hormone (TRH) is the main positive regulator of thyrotropin (TSH) secretion. TRH action and the negative feedback of thyroid hormone are integrated in order to guarantee appropriate thyroid stimulation. TRH action affects various steps of the biosynthetic process within thyrotrophs, with major effects on the posttranslational maturation of TSH oligosaccharide chains, and is necessary for the secretion of the glycoprotein hormone with full biological activity. Since the first description in 1979 of some patients with central hypothyroidism of hypothalamic origin associated with the secretion of TSH molecules with conserved immunoreactivity but decreased bioactivity, a large body of evidence has accumulated in more recent years showing that changes of the oligosaccharide chains have a great impact on the biological properties of circulating TSH and occur in various in vivo situations. These findings have lead to the new concept of a qualitative regulation of TSH secretion. This can be achieved mainly through the transcriptional and posttranscriptional regulation of the complex enzymatic machinery devoted to the processing of the three oligosaccharide chains linked to specific asparagine residues of TSH heterodimer. Data obtained in several physiological and pathological conditions, which are characterized by an increased or diminished TRH action, indicate that both qualitative and quantitative regulations cooperate within thyrotrophs in order to adjust thyroid-stimulating activity to the temporary needs.
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Affiliation(s)
- L Persani
- Università di Milano, Laboratorio Sperimentale di Ricerche Endocrinologiche, Istituto Auxologico Italiano IRCCS
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20
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Fares FA, Yamabe S, Ben-Menahem D, Pixley M, Hsueh AJ, Boime I. Conversion of thyrotropin heterodimer to a biologically active single-chain. Endocrinology 1998; 139:2459-64. [PMID: 9564858 DOI: 10.1210/endo.139.5.6021] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
TSH and the gonadotropins, FSH, LH, and CG are a family of heterodimeric glycoprotein hormones composed of a common alpha-subunit noncovalently linked to a hormone specific beta-subunit. Assembly of alpha- and beta-subunits is essential for hormone-specific posttranslational modifications, receptor binding, and bioactivity. Structure-function studies of TSH and gonadotropins using site-directed mutagenesis can often affect folding, assembly, and secretion of the hormone. To circumvent these difficulties, recently, the gonadotropin heterodimers were converted to single chains. Here we converted the hTSH heterodimer to a biologically active single chain by genetically fusing the amino terminal end of the common alpha-subunit to the carboxyl terminal end of hTSHbeta in the presence or absence of hCGbeta carboxyl terminal peptide (CTP), which was used as a linker. Wild-type hTSH and the single chains were expressed in Chinese hamster ovary (CHO) cells, and they were efficiently secreted. Although the secretion rate of the single chain was 3-fold higher than that of hTSH wild-type. Moreover, the secretion of the single chain in the presence of the CTP linker was dramatically increased. On the other hand, receptor binding and in vitro bioactivity of the single chains were similar to that of hTSH wild-type. These data indicate the potential of the single chain approach to further investigate structure-function relationships of TSH.
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Affiliation(s)
- F A Fares
- Department of Biochemistry, Carmel Medical Center, and the Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
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21
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Sanders J, Oda Y, Roberts SA, Maruyama M, Furmaniak J, Smith BR. Understanding the thyrotropin receptor function-structure relationship. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1997; 11:451-79. [PMID: 9532334 DOI: 10.1016/s0950-351x(97)80693-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The thyrotropin (TSH) receptor (TSHR) is a key protein in the control of thyroid function and a major thyroid autoantigen. Recently, molecular cloning of the receptor has been carried out and we now review the impact of this work on our understanding of the physiology and pathophysiology of the TSHR. Analysis of recombinant TSHR proteins expressed in prokaryotic and eukaryotic systems has indicated that post-translational processing is important for the formation of active receptors. Studies of TSHR glycosylation have shown that a 'mature' form of the receptor containing mainly complex-type sugar residues is principally involved in TSH and TSHR autoantibody (TRAb) binding. In addition, the processing of the TSHR peptide chain into two subunits observed with native TSHR has been confirmed using recombinant TSHR. However, despite considerable efforts in many laboratories, the binding site(s) for TSH and TRAb on the TSHR have not been well characterized as yet and lessons learned from the discovery of naturally occurring amino acid mutations of the TSHR confirm the complexity of the hormone and autoantibody binding sites. Future progress in producing large amounts of pure TSHR as well as monoclonal TRAbs, followed by crystallographic analysis of TSHR-TSH complexes and TSHR-TRAb complexes, should be helpful in providing a better insight into the relationship between TSHR structure and function.
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Affiliation(s)
- J Sanders
- FIRS Laboratories, RSR Ltd, Llanishen, Cardiff, UK
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22
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Grossmann M, Weintraub BD, Szkudlinski MW. Novel insights into the molecular mechanisms of human thyrotropin action: structural, physiological, and therapeutic implications for the glycoprotein hormone family. Endocr Rev 1997; 18:476-501. [PMID: 9267761 DOI: 10.1210/edrv.18.4.0305] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M Grossmann
- Department of Medicine, University of Maryland School of Medicine, Baltimore, USA
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23
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Grossmann M, Szkudlinski MW, Wong R, Dias JA, Ji TH, Weintraub BD. Substitution of the seat-belt region of the thyroid-stimulating hormone (TSH) beta-subunit with the corresponding regions of choriogonadotropin or follitropin confers luteotropic but not follitropic activity to chimeric TSH. J Biol Chem 1997; 272:15532-40. [PMID: 9182589 DOI: 10.1074/jbc.272.24.15532] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The region between the 10th and 12th cysteine (Cys88-Cys105 in human thyroid-stimulating hormone beta-subunit (hTSHbeta)) of the glycoprotein hormone beta-subunits corresponds to the disulfide-linked seat-belt region. It wraps around the common alpha-subunit and has been implicated in regulating specificity between human choriogonadotropin (hCG) and human follicle-stimulating hormone (hFSH), but determinants of hTSH specificity are unknown. To characterize the role of this region for hTSH, we constructed hTSH chimeras in which the entire seat-belt region Cys88-Cys105 or individual intercysteine segments Cys88-Cys95 and Cys95-Cys105 were replaced with the corresponding sequences of hCG and hFSH or alanine cassettes. Alanine cassette mutagenesis of hTSH showed that the Cys95-Cys105 segment of the seat-belt was more important for TSH receptor binding and signal transduction than the Cys88-Cys95 determinant loop region. Replacing the entire seat-belt of hTSHbeta with the hCG sequence conferred full hCG receptor binding and activation to the hTSH chimera, whereas TSH receptor binding and activation were abolished. Conversely, introduction of the hTSHbeta seat-belt sequence into hCGbeta generated an hCG chimera that bound to and activated the TSH receptor but not the CG/lutropin (LH) receptor. In contrast, an hTSH chimera bearing hFSH seat-belt residues did not possess any follitropic activity, and its thyrotropic activity was only slightly reduced. This may in part be due to the fact that the net charge of the seat-belt is similar in hTSH and hFSH but different from hCG. However, exchanging other regions of charge heterogeneity between hTSHbeta and hFSHbeta did not confer follitropic activity to hTSH. Thus, exchanging the seat-belt region between hTSH and hCG switches hormonal specificity in a mutually exclusive fashion. In contrast, the seat-belt appears not to discriminate between the TSH and the FSH receptors, indicating for the first time that domains outside the seat-belt region contribute to glycoprotein hormone specificity.
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Affiliation(s)
- M Grossmann
- Laboratory of Molecular Endocrinology, Department of Medicine, University of Maryland School of Medicine and the Institute of Human Virology, Medical Biotechnology Center, Baltimore, Maryland 21201, USA.
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24
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Szkudlinski MW, Teh NG, Grossmann M, Tropea JE, Weintraub BD. Engineering human glycoprotein hormone superactive analogues. Nat Biotechnol 1996; 14:1257-63. [PMID: 9631089 DOI: 10.1038/nbt1096-1257] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report the generation of superactive analogues of human glycoprotein hormones, with potential applications in thyroid and reproductive disorders. Current biological and structural data were used to rationalize mutagenesis. The 11-20 region in the alpha-subunit with a cluster of lysine residues forms a previously unrecognized domain critical for receptor binding and signal transduction, as well as an important motif in the evolution of glycoprotein hormone activities. The gradual elimination of basic residues in the alpha-subunit coincided with the evolutionary divergence of the hominids from the Old World monkeys. By selective reconstitution of certain critical residues present in homologous nonhuman hormones we have developed human thyroid stimulating hormone and chorionic gonadotropin analogues with substantial increases in receptor binding affinity and bioactivity, thus providing a paradigm for the design of novel therapeutic protein analogues.
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Affiliation(s)
- M W Szkudlinski
- Department of Medicine, University of Maryland School of Medicine, Baltimore 21201, USA.
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