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Byambaragchaa M, Choi SH, Kim DW, Min KS. Constitutive Activating Eel Luteinizing Hormone Receptors Induce Constitutively Signal Transduction and Inactivating Mutants Impair Biological Activity. Dev Reprod 2021; 25:133-143. [PMID: 34950817 PMCID: PMC8670774 DOI: 10.12717/dr.2021.25.3.133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/19/2021] [Accepted: 08/25/2021] [Indexed: 11/17/2022]
Abstract
In contrast to the human lutropin receptor (hLHR) and rat LHR (rLHR), very few
naturally occurring mutants in other mammalian species have been identified. The
present study aimed to delineate the mechanism of signal transduction by three
constitutively activating mutants (designated M410T, L469R, and D590Y) and two
inactivating mutants (D383N and Y546F) of the eel LHR, known to be naturally
occurring in human LHR transmembrane domains. The mutants were constructed and
measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous
time-resolved fluorescence assays in Chinese hamster ovary (CHO)-K1 cells. The
activating mutant cells expressing eel LHR-M410T, L469R, and D590Y exhibited a
4.0-, 19.1-, and 7.8-fold increase in basal cAMP response without agonist
treatment, respectively. However, inactivating mutant cells expressing D417N and
Y558F did not completely impaired signal transduction. Specifically, signal
transduction in the cells expressing activating mutant L469R was not occurred
with a further ligand stimulation, showing that the maximal response exhibited
approximately 53% of those of wild type receptor. Our results suggested that the
constitutively activating mutants of the eel LHR consistently occurred without
agonist treatment. These results provide important information of LHR function
in fish and regulation with regard to mutations of highly conserved amino acids
in glycoprotein hormone receptors.
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Affiliation(s)
| | - Seung-Hee Choi
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Dong-Wan Kim
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea.,School of Animal Life Convergence Science, Hankyong National University, Ansung 17579, Korea
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Byambaragchaa M, Choi SH, Kim DW, Min KS. Cell-Surface Loss of Constitutive Activating and Inactivating Mutants of Eel Luteinizing Hormone Receptors. Dev Reprod 2021; 25:225-234. [PMID: 35141448 PMCID: PMC8807125 DOI: 10.12717/dr.2021.25.4.225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/02/2021] [Accepted: 12/11/2021] [Indexed: 12/14/2022]
Abstract
The present study aimed to investigate the mechanism of cell surface receptor loss by two constitutively activating mutants (designated L469R, and D590Y) and two inactivating mutants (D417N and Y558F) of the luteinizing hormone receptor (LHR) in the Japanese eel Anguilla japonica, known to naturally occur in human LHR transmembrane domains. We investigated cell surface receptor loss using an enzyme-linked immunosorbent assay in HEK 293 cells. The expression level of wild-type eel LHR was considered to be 100%, and the expression levels of L469R and D417N were 97% and 101%, respectively, whereas the expression levels of D590Y and Y558F slightly increased to approximately 110% and 106%, respectively. The constitutively activating mutants L469R and D590Y exhibited a decrease in cell surface loss in a manner similar to that of wild-type eel LHR. The rates of loss of cell surface agonist-receptor complexes were observed to be very rapid (2.6-6.2 min) in both the wild-type eel LHR and activating mutants. However, cell surface receptor loss in the cells expressing inactivating mutants D417N and Y558F was slightly observed in the cells expressing inactivating mutants D417N and Y558F, despite treatment with a high concentration of agonist. These results provide important information on LHR function in fish and the regulation of mutations of highly conserved amino acids in glycoprotein hormone receptors.
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Affiliation(s)
| | - Seung-Hee Choi
- School of Animal Life Convergence Science, Hankyong National University, Ansung 17579, Korea
| | - Dong-Wan Kim
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea.,School of Animal Life Convergence Science, Hankyong National University, Ansung 17579, Korea
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3
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Byambaragchaa M, Seong HK, Choi SH, Kim DJ, Kang MH, Min KS. Constitutively Activating Mutants of Equine LH/CGR Constitutively Induce Signal Transduction and Inactivating Mutations Impair Biological Activity and Cell-Surface Receptor Loss In Vitro. Int J Mol Sci 2021; 22:ijms221910723. [PMID: 34639064 PMCID: PMC8509413 DOI: 10.3390/ijms221910723] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 12/26/2022] Open
Abstract
The signal transduction of the equine lutropin/choriogonadotropin receptor (eLH/CGR) is unclear in naturally occurring activating/inactivating mutants of this receptor, which plays an important role in reproductive physiology. We undertook the present study to determine whether conserved structurally related mutations in eLH/CGR exhibit similar mechanisms of signal transduction. We constructed four constitutively activating mutants (M398T, L457R, D564G, and D578Y) and three inactivating mutants (D405N, R464H, and Y546F); measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary cells; and investigated cell-surface receptor loss using an enzyme-linked immunosorbent assay in human embryonic kidney 293 cells. The eLH/CGR-L457R-, -D564G-, and -D578Y-expressing cells exhibited 16.9-, 16.4-, and 11.2-fold increases in basal cAMP response, respectively. The eLH/CGR-D405N- and R464H-expressing cells presented a completely impaired signal transduction, whereas the Y546F-expressing cells exhibited a small increase in cAMP response. The cell-surface receptor loss was 1.4- to 2.4-fold greater in the activating-mutant-expressing cells than in wild-type eLH/CGR-expressing cells, but was completely impaired in the D405N- and Y546F-expressing cells, despite treatment with a high concentration of agonist. In summary, the state of activation of eLH/CGR influenced agonist-induced cell-surface receptor loss, which was directly related to the signal transduction of constitutively activating mutants.
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Affiliation(s)
- Munkhzaya Byambaragchaa
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
| | - Hoon-Ki Seong
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
| | - Seung-Hee Choi
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea;
| | - Dae-Jung Kim
- Jeju Fisheries Research Institute, National Institute of Fisheries Science (NIFS), Jeju 63610, Korea;
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan 31499, Korea;
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea;
- Correspondence: ; Tel.: +82-31-670-5421; Fax: +82-31-670-5417
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Byambaragchaa M, Ahn TY, Choi SH, Kang MH, Min KS. Functional characterization of naturally-occurring constitutively activating/inactivating mutations in equine follicle-stimulating hormone receptor (eFSHR). Anim Biosci 2021; 35:399-409. [PMID: 34474536 PMCID: PMC8902225 DOI: 10.5713/ab.21.0246] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/12/2021] [Indexed: 11/27/2022] Open
Abstract
Objective Follicle-stimulating hormone (FSH) is the central hormone involved in mammalian reproduction, maturation at puberty, and gamete production that mediates its function by control of follicle growth and function. The present study investigated the mutations involved in the regulation of FSH receptor (FSHR) activation. Methods We analyzed seven naturally-occurring mutations that were previously reported in human FSHR (hFSHR), in the context of equine FSHR (eFSHR); these include one constitutively activation variant, one allelic variant, and five inactivating variants. These mutations were introduced into wild-type eFSHR (eFSHR-wt) sequence to generate mutants that were designated as eFSHR-D566G, -A306T, -A189V, -N191I, -R572C, -A574V, and -R633H. Mutants were transfected into PathHunter EA-parental CHO-K1 cells expressing β-arrestin. The biological function of mutants was analyzed by quantitating cAMP accumulation in cells incubated with increasing concentrations of FSH. Results Cells expressing eFSHR-D566G exhibited an 8.6-fold increase in basal cAMP response, as compared to that in eFSHR-wt. The allelic variation mutant eFSHR-A306T was not found to affect the basal cAMP response or EC50 levels. On the other hand, eFSHR-D566G and eFSHR-A306T displayed a 1.5- and 1.4-fold increase in the maximal response, respectively. Signal transduction was found to be completely impaired in case of the inactivating mutants eFSHR-A189V, -R572C, and -A574V. When compared with eFSHR-wt, eFSHR-N191I displayed a 5.4-fold decrease in the EC50 levels (3910 ng/mL) and a 2.3-fold decrease in the maximal response. In contrast, cells expressing eFSHR-R633H displayed in a similar manner to that of the cells expressing the eFSHR-wt on signal transduction and maximal response. Conclusion The activating mutant eFSHR-D566G greatly enhanced the signal transduction in response to FSH, in the absence of agonist treatment. We suggest that the state of activation of the eFSHR can modulate its basal cAMP accumulation.
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Affiliation(s)
- Munkhzaya Byambaragchaa
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea
| | - Tae-Young Ahn
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea
| | - Seung-Hee Choi
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan 31499, Korea
| | - Kwan-Sik Min
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea.,School of Animal Life Convergence Science, Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
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Constitutive Activation and Inactivation of Mutations Inducing Cell Surface Loss of Receptor and Impairing of Signal Transduction of Agonist-Stimulated Eel Follicle-Stimulating Hormone Receptor. Int J Mol Sci 2020; 21:ijms21197075. [PMID: 32992880 PMCID: PMC7583038 DOI: 10.3390/ijms21197075] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/23/2020] [Accepted: 09/23/2020] [Indexed: 12/17/2022] Open
Abstract
In the present study, we investigated the signal transduction of mutants of the eel follicle-stimulating hormone receptor (eelFSHR). Specifically, we examined the constitutively activating mutant D540G in the third intracellular loop, and four inactivating mutants (A193V, N195I, R546C, and A548V). To directly assess functional effects, we conducted site-directed mutagenesis to generate mutant receptors. We measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary (CHO-K1) cells and investigated cell surface receptor loss using an enzyme-linked immunosorbent assay in human embryonic kidney (HEK) 293 cells. The cells expressing eelFSHR-D540G exhibited a 23-fold increase in the basal cAMP response without agonist treatment. The cells expressing A193V, N195I, and A548V mutants had completely impaired signal transduction, whereas those expressing the R546C mutant exhibited little increase in cAMP responsiveness and a small increase in signal transduction. Cell surface receptor loss in the cells expressing inactivating mutants A193V, R546C, and A548V was clearly slower than in the cell expressing the wild-type eelFSHR. However, cell surface receptor loss in the cells expressing inactivating mutant N195I decreased in a similar manner to that of the cells expressing the wild-type eelFSHR or the activating mutant D540G, despite the completely impaired cAMP response. These results provide important information regarding the structure–function relationships of G protein-coupled receptors during signal transduction.
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Hsueh AJW, Feng Y. Discovery of polypeptide ligand-receptor pairs based on their co-evolution. FASEB J 2020; 34:8824-8832. [PMID: 32501617 DOI: 10.1096/fj.202000779r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/05/2020] [Accepted: 05/07/2020] [Indexed: 12/18/2022]
Abstract
Sequencing diverse genomes allowed the tracing of orthologous and paralogous genes to understand the co-evolution of polypeptide ligands and receptors. This review documents the discovery of several polypeptide ligands and their cognate receptors mainly expressed in the reproductive tissue using evolutionary genomics. We discussed the sub-functionization of paralogs and co-evolution of ligand-receptor families. Based on the conserved signaling among paralogous receptors and common knock-out phenotypes of ligand-receptor pairs, relationships between relaxin family peptides and leucine-rich repeat-containing, G protein-coupled receptors (LGR) were revealed. We also described the identification of a novel paralogous glycoprotein hormone thyrostimulin and design of a long-acting FSH. Human stresscopin and stresscopin-related peptide, paralogous to CRH, were also identified based on the conserved signaling pathways. Recently, a novel ligand placensin expressed in human placenta was found based on the paralogous relationship with a metabolic hormone asprosin. Placensin likely contributes to stage-dependent increases in insulin resistance during human pregnancy and its elevated secretion was associated with gestational diabetes mellitus. Although many ligands were predicted based on sequence signatures, ligands of shorter sequences have not been identified, together with many "orphan" receptors without known ligands. Future development of tools for predicting ligands and high throughput assays to identify ligand-receptor pairs based on ligand binding and/or signal transduction could advance hormone-based physiology and pathophysiology.
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Affiliation(s)
- Aaron J W Hsueh
- Division of Reproductive and Stem Cell Biology, Departments of Obstetrics and Gynecology, School of Medicine, Stanford University, Stanford, CA, USA
| | - Yi Feng
- Division of Reproductive and Stem Cell Biology, Departments of Obstetrics and Gynecology, School of Medicine, Stanford University, Stanford, CA, USA.,Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institute of Integrative Medicine, Institute of Brain Science, School of Basic Medical Sciences, Fudan University, Shanghai, China
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7
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Hsueh AJ, He J. Gonadotropins and their receptors: coevolution, genetic variants, receptor imaging, and functional antagonists. Biol Reprod 2019; 99:3-12. [PMID: 29462242 DOI: 10.1093/biolre/ioy012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/06/2018] [Indexed: 12/29/2022] Open
Abstract
Gonadotropins belong to the family of dimeric glycoprotein hormones and regulate gonadal physiology mediated by G protein-coupled, seven-transmembrane receptors. These glycoprotein hormones are widely used in the clinic to promote ovarian follicle development and for treating some cases of male infertility. We traced the coevolution of dimeric gonadotropin hormones and their receptors, together with thyrotropin and its receptor. We updated recent findings on human genetic variants of these genes and their association with dizygotic twining, polycystic ovarian syndrome, primary ovarian insufficiency, male-limited precocious puberty, and infertility. In addition to the known physiological roles of gonadotropin-receptor signaling in gonadal tissues, we also discussed emerging understanding of extragonadal functions of gonadotropins in bones and adipose tissues, together with recent advances in in vivo imaging of gonadotropin receptors in live animals. Recent development of gonadotropin receptor agonists and antagonists were summarized with an emphasis on the development of functional antagonists for FSH receptors to alleviate osteoporosis and obesity associated with menopause.
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Affiliation(s)
- Aaron J Hsueh
- Program of Reproductive and Stem Cell Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California, USA
| | - Jiahuan He
- Program of Reproductive and Stem Cell Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California, USA
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Ulloa-Aguirre A, Zariñán T, Jardón-Valadez E, Gutiérrez-Sagal R, Dias JA. Structure-Function Relationships of the Follicle-Stimulating Hormone Receptor. Front Endocrinol (Lausanne) 2018; 9:707. [PMID: 30555414 PMCID: PMC6281744 DOI: 10.3389/fendo.2018.00707] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/09/2018] [Indexed: 12/16/2022] Open
Abstract
The follicle-stimulating hormone receptor (FSHR) plays a crucial role in reproduction. This structurally complex receptor is a member of the G-protein coupled receptor (GPCR) superfamily of membrane receptors. As with the other structurally similar glycoprotein hormone receptors (the thyroid-stimulating hormone and luteinizing hormone-chorionic gonadotropin hormone receptors), the FSHR is characterized by an extensive extracellular domain, where binding to FSH occurs, linked to the signal specificity subdomain or hinge region. This region is involved in ligand-stimulated receptor activation whereas the seven transmembrane domain is associated with receptor activation and transmission of the activation process to the intracellular loops comprised of amino acid sequences, which predicate coupling to effectors, interaction with adapter proteins, and triggering of downstream intracellular signaling. In this review, we describe the most important structural features of the FSHR intimately involved in regulation of FSHR function, including trafficking, dimerization, and oligomerization, ligand binding, agonist-stimulated activation, and signal transduction.
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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 Salvador Zubirán, Mexico City, Mexico
- *Correspondence: Alfredo Ulloa-Aguirre
| | - Teresa Zariñán
- Red de Apoyo a la Investigación, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Eduardo Jardón-Valadez
- Departamento de Ciencias Ambientales, Universidad Autónoma Metropolitana Unidad Lerma, Lerma, Mexico
| | - Rubén Gutiérrez-Sagal
- Red de Apoyo a la Investigación, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - James A. Dias
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, United States
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Ulloa-Aguirre A, Zariñán T. The Follitropin Receptor: Matching Structure and Function. Mol Pharmacol 2016; 90:596-608. [DOI: 10.1124/mol.116.104398] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/28/2016] [Indexed: 12/19/2022] Open
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Liu Y, An S, Ward R, Yang Y, Guo XX, Li W, Xu TR. G protein-coupled receptors as promising cancer targets. Cancer Lett 2016; 376:226-39. [PMID: 27000991 DOI: 10.1016/j.canlet.2016.03.031] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/14/2016] [Accepted: 03/14/2016] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) regulate an array of fundamental biological processes, such as growth, metabolism and homeostasis. Specifically, GPCRs are involved in cancer initiation and progression. However, compared with the involvement of the epidermal growth factor receptor in cancer, that of GPCRs have been largely ignored. Recent findings have implicated many GPCRs in tumorigenesis, tumor progression, invasion and metastasis. Moreover, GPCRs contribute to the establishment and maintenance of a microenvironment which is permissive for tumor formation and growth, including effects upon surrounding blood vessels, signaling molecules and the extracellular matrix. Thus, GPCRs are considered to be among the most useful drug targets against many solid cancers. Development of selective ligands targeting GPCRs may provide novel and effective treatment strategies against cancer and some anticancer compounds are now in clinical trials. Here, we focus on tumor related GPCRs, such as G protein-coupled receptor 30, the lysophosphatidic acid receptor, angiotensin receptors 1 and 2, the sphingosine 1-phosphate receptors and gastrin releasing peptide receptor. We also summarize their tissue distributions, activation and roles in tumorigenesis and discuss the potential use of GPCR agonists and antagonists in cancer therapy.
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Affiliation(s)
- Ying Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Richard Ward
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Yang Yang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Xiao-Xi Guo
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Wei Li
- Kidney Cancer Research, Diagnosis and Translational Technology Center of Yunnan Province, Department of Urology, The People's Hospital of Yunnan Province, Kunming, Yunnan 650032, China.
| | - Tian-Rui Xu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
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Ulloa-Aguirre A, Reiter E, Bousfield G, Dias JA, Huhtaniemi I. Constitutive activity in gonadotropin receptors. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 70:37-80. [PMID: 24931192 DOI: 10.1016/b978-0-12-417197-8.00002-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Constitutively active mutants (CAMs) of gonadotropin receptors are, in general, rare conditions. Luteinizing hormone-choriogonadotropin receptor (LHCGR) CAMs provoke the dramatic phenotype of familial gonadotropin-independent isosexual male-limited precocious puberty, whereas in females, there is not yet any identified phenotype. Only one isolated follicle-stimulating hormone receptor (FSHR) CAM (Asp567Gly) has so far been detected in a single male patient, besides other FSHR weak CAMs linked to pregnancy-associated ovarian hyperstimulation syndrome or to impaired desensitization and internalization. Several animal models have been developed for studying enhanced gonadotropin action; in addition to unraveling valuable new information about the possible phenotypes of isolated FSHR and LHCGR CAMs in women, the information obtained from these mouse models has served multiple translational goals, including the development of new diagnostic and therapeutic targets as well as the prediction of phenotypes for mutations not yet identified in humans. Mutagenesis and computational studies have shed important information on the physiopathogenic mechanisms leading to constitutive activity of gonadotropin receptors; a common feature in these receptor CAMs is the release of stabilizing interhelical interactions between transmembrane domains (TMDs) 3 and 6 leading to an increase, with respect to the wild-type receptor, in the solvent accessibility at the cytosolic extension of TMDs 3, 5, and 6, which involves the highly conserved Glu/Asp-Arg-Tyr/Trp sequence. In this chapter, we summarize the structural features, functional consequences, and mechanisms that lead to constitutive activation of gonadotropin receptor CAMs and provide information on pharmacological approaches that might potentially modulate gonadotropin receptor CAM function.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Research Support Network, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" and Universidad Nacional Autónoma de México, México D.F., Mexico.
| | - Eric Reiter
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; BIOS Group, INRA, UMR85, Unité Physiologie de la Reproduction et des Comportements, Nouzilly, France; CNRS, UMR7247, Nouzilly, France; Université François Rabelais, Tours, France
| | - George Bousfield
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Department of Biological Sciences, Wichita State University, Wichita, Kansas, USA
| | - James A Dias
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, USA
| | - Ilpo Huhtaniemi
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
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Deng C, Reddy P, Cheng Y, Luo CW, Hsiao CL, Hsueh AJW. Multi-functional norrin is a ligand for the LGR4 receptor. J Cell Sci 2013; 126:2060-8. [PMID: 23444378 DOI: 10.1242/jcs.123471] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mammalian LGR4, 5 and 6 are seven-transmembrane receptors that are important for diverse physiological processes. These receptors are orthologous to DLGR2, a Drosophila receptor activated by the burs/pburs heterodimer important for morphogenesis. Although recent studies indicated that four R-spondin proteins are cognate ligands for LGR4, 5 and 6 receptors, several BMP antagonists in vertebrates have been postulated to be orthologous to burs and pburs. Using newly available genome sequences, we showed that norrin is a vertebrate ortholog for insect burs and pburs and stimulates Wnt signaling mediated by LGR4, but not by LGR5 and 6, in mammalian cells. Although norrin could only activate LGR4, binding studies suggested interactions between norrin and LGR4, 5 and 6. Norrin, the Norrie disease gene product, is also capable of activating Wnt signaling mediated by the Frizzled4 receptor and serves as a BMP antagonist. Mutagenesis studies indicated that different norrin mutations found in patients with Norrie disease can be categorized into subgroups according to defects for signaling through the three distinct binding proteins. Thus, norrin is a rare ligand capable of binding three receptors/binding proteins that are important for BMP and Wnt signaling pathways.
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Affiliation(s)
- Cheng Deng
- Program of Reproductive and Stem Cell Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA 94305-5317, USA
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Xie XQ, Chowdhury A. Advances in methods to characterize ligand-induced ionic lock and rotamer toggle molecular switch in G protein-coupled receptors. Methods Enzymol 2013; 520:153-74. [PMID: 23332699 DOI: 10.1016/b978-0-12-391861-1.00007-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Structural biology of GPCRs has made significant progress upon recently developed technologies for GPCRs expression/purification and elucidation of GPCRs crystal structures. The crystal structures provide a snapshot of the receptor structural disposition of GPCRs itself or with cocrystallized ligands, and the results are congruent with biophysical and computer modeling studies reported about GPCRs conformational and dynamics flexibility, regulated activation, and the various stabilizing interactions, such as "molecular switches." The molecular switches generally constitute the most conserved domains within a particular GPCR superfamily. Often agonist-induced receptor activation proceeds by the disruption of majority of these interactions, while antagonist and inverse agonist act as blockers and structural stabilizers, respectively. Several elegant studies, particularly for the β2AR, have demonstrated the relationship between ligand structure, receptor conformational changes, and corresponding pharmacological outcomes. Thus, it is of great importance to understand GPCRs activation related to cell signaling pathways. Herein, we summarize the steps to produce functional GPCRs, generate suitably fluorescent labeled GPCRs and the procedure to use that to understand if ligand-induced activation can proceed by activation of the GPCRs via ionic lock switch and/or rotamer toggle switch mechanisms. Such understanding of ligand structure and mechanism of receptor activation will provide great insight toward uncovering newer pathways of GPCR activation and aid in structure-based drug design.
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Affiliation(s)
- Xiang-Qun Xie
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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14
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Coviello AD, Haring R, Wellons M, Vaidya D, Lehtimäki T, Keildson S, Lunetta KL, He C, Fornage M, Lagou V, Mangino M, Onland-Moret NC, Chen B, Eriksson J, Garcia M, Liu YM, Koster A, Lohman K, Lyytikäinen LP, Petersen AK, Prescott J, Stolk L, Vandenput L, Wood AR, Zhuang WV, Ruokonen A, Hartikainen AL, Pouta A, Bandinelli S, Biffar R, Brabant G, Cox DG, Chen Y, Cummings S, Ferrucci L, Gunter MJ, Hankinson SE, Martikainen H, Hofman A, Homuth G, Illig T, Jansson JO, Johnson AD, Karasik D, Karlsson M, Kettunen J, Kiel DP, Kraft P, Liu J, Ljunggren Ö, Lorentzon M, Maggio M, Markus MRP, Mellström D, Miljkovic I, Mirel D, Nelson S, Morin Papunen L, Peeters PHM, Prokopenko I, Raffel L, Reincke M, Reiner AP, Rexrode K, Rivadeneira F, Schwartz SM, Siscovick D, Soranzo N, Stöckl D, Tworoger S, Uitterlinden AG, van Gils CH, Vasan RS, Wichmann HE, Zhai G, Bhasin S, Bidlingmaier M, Chanock SJ, De Vivo I, Harris TB, Hunter DJ, Kähönen M, Liu S, Ouyang P, Spector TD, van der Schouw YT, Viikari J, Wallaschofski H, McCarthy MI, Frayling TM, Murray A, Franks S, Järvelin MR, de Jong FH, Raitakari O, Teumer A, Ohlsson C, Murabito JM, Perry JRB. A genome-wide association meta-analysis of circulating sex hormone-binding globulin reveals multiple Loci implicated in sex steroid hormone regulation. PLoS Genet 2012; 8:e1002805. [PMID: 22829776 PMCID: PMC3400553 DOI: 10.1371/journal.pgen.1002805] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 05/19/2012] [Indexed: 01/28/2023] Open
Abstract
Sex hormone-binding globulin (SHBG) is a glycoprotein responsible for the transport and biologic availability of sex steroid hormones, primarily testosterone and estradiol. SHBG has been associated with chronic diseases including type 2 diabetes (T2D) and with hormone-sensitive cancers such as breast and prostate cancer. We performed a genome-wide association study (GWAS) meta-analysis of 21,791 individuals from 10 epidemiologic studies and validated these findings in 7,046 individuals in an additional six studies. We identified twelve genomic regions (SNPs) associated with circulating SHBG concentrations. Loci near the identified SNPs included SHBG (rs12150660, 17p13.1, p = 1.8 × 10(-106)), PRMT6 (rs17496332, 1p13.3, p = 1.4 × 10(-11)), GCKR (rs780093, 2p23.3, p = 2.2 × 10(-16)), ZBTB10 (rs440837, 8q21.13, p = 3.4 × 10(-09)), JMJD1C (rs7910927, 10q21.3, p = 6.1 × 10(-35)), SLCO1B1 (rs4149056, 12p12.1, p = 1.9 × 10(-08)), NR2F2 (rs8023580, 15q26.2, p = 8.3 × 10(-12)), ZNF652 (rs2411984, 17q21.32, p = 3.5 × 10(-14)), TDGF3 (rs1573036, Xq22.3, p = 4.1 × 10(-14)), LHCGR (rs10454142, 2p16.3, p = 1.3 × 10(-07)), BAIAP2L1 (rs3779195, 7q21.3, p = 2.7 × 10(-08)), and UGT2B15 (rs293428, 4q13.2, p = 5.5 × 10(-06)). These genes encompass multiple biologic pathways, including hepatic function, lipid metabolism, carbohydrate metabolism and T2D, androgen and estrogen receptor function, epigenetic effects, and the biology of sex steroid hormone-responsive cancers including breast and prostate cancer. We found evidence of sex-differentiated genetic influences on SHBG. In a sex-specific GWAS, the loci 4q13.2-UGT2B15 was significant in men only (men p = 2.5 × 10(-08), women p = 0.66, heterogeneity p = 0.003). Additionally, three loci showed strong sex-differentiated effects: 17p13.1-SHBG and Xq22.3-TDGF3 were stronger in men, whereas 8q21.12-ZBTB10 was stronger in women. Conditional analyses identified additional signals at the SHBG gene that together almost double the proportion of variance explained at the locus. Using an independent study of 1,129 individuals, all SNPs identified in the overall or sex-differentiated or conditional analyses explained ~15.6% and ~8.4% of the genetic variation of SHBG concentrations in men and women, respectively. The evidence for sex-differentiated effects and allelic heterogeneity highlight the importance of considering these features when estimating complex trait variance.
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Affiliation(s)
- Andrea D. Coviello
- Section of Preventive Medicine and Epidemiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Heart, Lung, and Blood Institute's The Framingham Heart Study, Framingham, Massachusetts, United States of America
| | - Robin Haring
- Institute for Clinical Chemistry and Laboratory Medicine, University Medicine, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
| | - Melissa Wellons
- Department of Medicine and Department of Obstetrics and Gynecology, The University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Dhananjay Vaidya
- Department of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Terho Lehtimäki
- Department of Clinical Chemistry, Fimlab Laboratories, Tampere University Hospital and University of Tampere School of Medicine, Tampere, Finland
| | - Sarah Keildson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kathryn L. Lunetta
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, United States of America
| | - Chunyan He
- Department of Public Health, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Melvin and Bren Simon Cancer Center, Indiana University, Indianapolis, Indiana, United States of America
| | - Myriam Fornage
- University of Texas Health Sciences Center at Houston, Houston, Texas, United States of America
| | - Vasiliki Lagou
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Massimo Mangino
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
| | - N. Charlotte Onland-Moret
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Brian Chen
- Program on Genomics and Nutrition and the Center for Metabolic Disease Prevention, School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America
| | - Joel Eriksson
- Center for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Melissa Garcia
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Yong Mei Liu
- Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
- Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America
| | - Annemarie Koster
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Kurt Lohman
- Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Leo-Pekka Lyytikäinen
- Department of Clinical Chemistry, Fimlab Laboratories, Tampere University Hospital and University of Tampere School of Medicine, Tampere, Finland
| | - Ann-Kristin Petersen
- Institute of Genetic Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Jennifer Prescott
- Program in Molecular and Genetic Epidemiology, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lisette Stolk
- Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
- Netherlands Consortium of Healthy Aging, Rotterdam, The Netherlands
| | - Liesbeth Vandenput
- Center for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Andrew R. Wood
- Genetics of Complex Traits, Peninsula Medical School, University of Exeter, Exeter, United Kingdom
| | - Wei Vivian Zhuang
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, United States of America
| | - Aimo Ruokonen
- Institute of Diagnostics, University of Oulu, Oulu, Finland
| | | | - Anneli Pouta
- National Institute for Health and Welfare and Institute of Health Sciences, University of Oulu, Oulu, Finland
| | | | - Reiner Biffar
- Department of Prosthetic Dentistry, Gerostomatology, and Dental Materials, University of Greifswald, Greifswald, Germany
| | - Georg Brabant
- Experimental and Clinical Endocrinology, University of Lübeck, Lübeck, Germany
| | - David G. Cox
- Cancer Research Center of Lyon, INSERM U1052, Lyon, France
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London, United Kingdom
| | - Yuhui Chen
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Steven Cummings
- California Pacific Medical Center, San Francisco, California, United States of America
| | - Luigi Ferrucci
- Longitudinal Studies Section, Clinical Research Branch, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Marc J. Gunter
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London, United Kingdom
| | - Susan E. Hankinson
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Biostatistics and Epidemiology, University of Massachusetts, Amherst, Massachusetts, United States of America
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Hannu Martikainen
- Department of Obstetrics and Gynecology, University Hospital of Oulu, Oulu, Finland
| | - Albert Hofman
- Netherlands Consortium of Healthy Aging, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands
| | - Georg Homuth
- Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - Thomas Illig
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
- Hannover Unified Biobank, Hannover Medical School, Hannover, Germany
| | - John-Olov Jansson
- Center for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Andrew D. Johnson
- National Heart, Lung, and Blood Institute's The Framingham Heart Study, Framingham, Massachusetts, United States of America
| | - David Karasik
- Hebrew SeniorLife Institute for Aging Research and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Magnus Karlsson
- Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences and Department of Orthopaedics, Lund University, Malmö, Sweden
| | - Johannes Kettunen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
| | - Douglas P. Kiel
- Hebrew SeniorLife Institute for Aging Research and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Peter Kraft
- Program in Molecular and Genetic Epidemiology, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Jingmin Liu
- Women's Health Initiative Clinical Coordinating Center, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Östen Ljunggren
- Department of Medical Sciences, University of Uppsala, Uppsala, Sweden
| | - Mattias Lorentzon
- Center for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Marcello Maggio
- Department of Internal Medicine and Biomedical Sciences, Section of Geriatrics, University of Parma, Parma, Italy
| | | | - Dan Mellström
- Center for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Iva Miljkovic
- University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Daniel Mirel
- Gene Environment Initiative, Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Boston, Massachusetts, United States of America
| | - Sarah Nelson
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| | - Laure Morin Papunen
- Department of Obstetrics and Gynecology, University Hospital of Oulu, Oulu, Finland
| | - Petra H. M. Peeters
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Inga Prokopenko
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Leslie Raffel
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Martin Reincke
- Medizinische Klinik and Poliklinik IV, Ludwig-Maximilians University, Munich, Germany
| | - Alex P. Reiner
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Kathryn Rexrode
- Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Fernando Rivadeneira
- Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
- Netherlands Consortium of Healthy Aging, Rotterdam, The Netherlands
| | - Stephen M. Schwartz
- Cardiovascular Health Research Unit, Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
| | - David Siscovick
- Cardiovascular Health Research Unit, Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
| | - Nicole Soranzo
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
- Human Genetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Doris Stöckl
- Institute of Epidemiology II, Helmholtz Zentrum München, Neuherberg, Germany
- Department of Obstetrics and Gynaecology, Ludwig-Maximilians-University, Munich, Germany
| | - Shelley Tworoger
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - André G. Uitterlinden
- Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
- Netherlands Consortium of Healthy Aging, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands
| | - Carla H. van Gils
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ramachandran S. Vasan
- Section of Preventive Medicine and Epidemiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Heart, Lung, and Blood Institute's The Framingham Heart Study, Framingham, Massachusetts, United States of America
| | - H.-Erich Wichmann
- Institute of Epidemiology I, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Medical Informatics, Biometry, and Epidemiology, Ludwig-Maximilians-Universität, Munich, Germany
- Klinikum Großhadern, Munich, Germany
| | - Guangju Zhai
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
- Discipline of Genetics, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Shalender Bhasin
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Martin Bidlingmaier
- Medizinische Klinik and Poliklinik IV, Ludwig-Maximilians University, Munich, Germany
| | - Stephen J. Chanock
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Immaculata De Vivo
- Program in Molecular and Genetic Epidemiology, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Tamara B. Harris
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, Maryland, United States of America
| | - David J. Hunter
- Program in Molecular and Genetic Epidemiology, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mika Kähönen
- Department of Clinical Physiology, Tampere University Hospital and University of Tampere School of Medicine, Tampere, Finland
| | - Simin Liu
- Program on Genomics and Nutrition, Department of Epidemiology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Pamela Ouyang
- Division of Cardiology, Johns Hopkins Bayview Medical Center, Baltimore, Maryland, United States of America
| | - Tim D. Spector
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
| | - Yvonne T. van der Schouw
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Jorma Viikari
- Department of Medicine, Turku University Hospital and University of Turku, Turku, Finland
| | - Henri Wallaschofski
- Institute for Clinical Chemistry and Laboratory Medicine, University Medicine, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
| | - Mark I. McCarthy
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom
- Oxford NIHR Biomedical Research Centre, Churchill Hospital, Oxford, United Kingdom
| | - Timothy M. Frayling
- Genetics of Complex Traits, Peninsula Medical School, University of Exeter, Exeter, United Kingdom
| | - Anna Murray
- Genetics of Complex Traits, Peninsula Medical School, University of Exeter, Exeter, United Kingdom
| | - Steve Franks
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
| | - Marjo-Riitta Järvelin
- Department of Biostatistics and Epidemiology, School of Public Health, MRC-HPA Centre for Environment and Health, Faculty of Medicine, Imperial College London, London, United Kingdom
- Institute of Health Sciences, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
- National Institute of Health and Welfare, University of Oulu, Oulu, Finland
| | - Frank H. de Jong
- Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Olli Raitakari
- Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital and Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
| | - Alexander Teumer
- Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - Claes Ohlsson
- Center for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Joanne M. Murabito
- National Heart, Lung, and Blood Institute's The Framingham Heart Study, Framingham, Massachusetts, United States of America
- Section of General Internal Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - John R. B. Perry
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
- Genetics of Complex Traits, Peninsula Medical School, University of Exeter, Exeter, United Kingdom
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Menon KMJ, Menon B. Structure, function and regulation of gonadotropin receptors - a perspective. Mol Cell Endocrinol 2012; 356:88-97. [PMID: 22342845 PMCID: PMC3327826 DOI: 10.1016/j.mce.2012.01.021] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 01/13/2012] [Accepted: 01/24/2012] [Indexed: 11/19/2022]
Abstract
Luteinizing hormone receptor and follicle stimulating hormone receptor play a crucial role in female and male reproduction. Significant new information has emerged about the structure, mechanism of activation, and regulation of expression of these receptors. Here we provide an overview of the current information on those aspects with an in-depth discussion of the recent developments in the post-transcriptional mechanism of LH receptor expression mediated by a specific LH receptor mRNA binding protein, designated as LRBP. LRBP was identified by electrophoretic gel mobility shift assay using cytosolic fractions from ovaries in the down regulated state. LRBP was purified, its binding site on LH receptor mRNA was identified and characterized. During ligand-induced down regulation, LRBP expression is increased through the cAMP/PKA and ERK signaling pathway, is translocated to translating ribosomes, binds LH receptor mRNA and forms an untranslatable ribonucleoprotein complex. This complex is then routed to the mRNA degradation machinery resulting in diminished levels of both LHR mRNA and cell surface expression of LH receptor. The studies leading to these conclusions are presented.
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Affiliation(s)
- K M J Menon
- Departments of Obstetrics/Gynecology and Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0617, United States.
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Abstract
Over the past 20 years, naturally occurring mutations that affect G protein-coupled receptors (GPCRs) have been identified, mainly in patients with endocrine diseases. The study of loss-of-function or gain-of-function mutations has contributed to our understanding of the pathophysiology of several diseases with classic hypophenotypes or hyperphenotypes of the target endocrine organs, respectively. Simultaneously, study of the mutant receptors ex vivo was instrumental in delineating the relationships between the structure and function of these important physiological and pharmacological molecules. Now that access to the crystallographic structure of a few GPCRs is available, the mechanics of these receptors can be studied at the atomic level. Progress in the fields of cell biology, molecular pharmacology and proteomics has also widened our view of GPCR functions. Initially considered simply as guanine nucleotide exchange factors capable of activating G protein-dependent regulatory cascades, GPCRs are now known to display several additional characteristics, each susceptible to alterations by disease-causing mutations. These characteristics include functionally important basal activity of the receptor; differential activation of various G proteins; differential activation of G protein-dependent and independent effects (biased agonism); interaction with proteins that modify receptor function; dimerization-dependent effects; and interaction with allosteric modulators. This Review attempts to illustrate how natural mutations of GPCR could contribute to our understanding of these novel facets of GPCR biology.
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Affiliation(s)
- Gilbert Vassart
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium.
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18
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Peltoketo H, Strauss L, Karjalainen R, Zhang M, Stamp GW, Segaloff DL, Poutanen M, Huhtaniemi IT. Female mice expressing constitutively active mutants of FSH receptor present with a phenotype of premature follicle depletion and estrogen excess. Endocrinology 2010; 151:1872-83. [PMID: 20172968 PMCID: PMC2851188 DOI: 10.1210/en.2009-0966] [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
Strong gain-of-function mutations have not been identified in humans in the FSH receptor (FSHR), whereas such mutations are common among many other G protein-coupled receptors. In order to predict consequences of such mutations on humans, we first identified constitutively activated mutants of the mouse (m) Fshr and then expressed them under the human anti-Müllerian hormone promoter in transgenic mice or created knock-in mutation into the mouse genome. We show here that mutations of Asp580 in the mFSHR significantly increase the basal receptor activity. D580H and D580Y mutations of mFSHR bind FSH, but the activity of the former is neither ligand-dependent nor promiscuous towards LH/human choriogonadotropin stimulation. Transgenic expression of mFshr(D580H) in granulosa cells leads to abnormal ovarian structure and function in the form of hemorrhagic cysts, accelerated loss of small follicles, augmented granulosa cell proliferation, increased estradiol biosynthesis, and occasional luteinized unruptured follicles or teratomas. The most affected mFshr(D580H) females are infertile with disturbed estrous cycle and decreased gonadotropin and increased prolactin levels. Increased estradiol and prolactin apparently underlie the enhanced development of the mammary glands, adenomatous pituitary growth, and lipofuscin accumulation in the adrenal gland. The influence of the mFSHR(D580Y) mutation is milder, mainly causing hemorrhagic cysts in transgenic mFSHR(D580Y) and mFSHR(D580Y) -knock-in mice. The results demonstrate that gain-of-function mutations of the FSHR in mice bring about distinct and clear changes in ovarian function, informative in the search of similar mutations in humans.
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Affiliation(s)
- Hellevi Peltoketo
- Institute of Reproductive and Developmental Biology, 2nd floor, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
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Tao YX, Segaloff DL. Follicle stimulating hormone receptor mutations and reproductive disorders. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 89:115-31. [PMID: 20374735 DOI: 10.1016/s1877-1173(09)89005-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The follicle stimulating hormone receptor (FSHR) plays a critical role in reproductive function. In the males, FSH supports spermatogenesis, whereas in females, FSH is absolutely required for ovarian follicle growth. In females, inactivating mutations in the FSHR result in ovarian dysgenesis with amenorrhea and infertility. The few males reported with severe inactivating mutations exhibited varying spermatogenic defects, but not azoospermia. While these findings may potentially suggest that FSH action is not absolutely required for spermatogenesis, it cannot be ruled out that these individuals have some residual FSHR activity. Gain-of-function mutations in the FSHR cause spontaneous ovarian hyperstimulation syndrome in females due to the inappropriate stimulation of the mutant FSHR by human choriogonadotropin.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Alabama 36849, USA
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Allan CM, Lim P, Robson M, Spaliviero J, Handelsman DJ. Transgenic mutant D567G but not wild-type human FSH receptor overexpression provides FSH-independent and promiscuous glycoprotein hormone Sertoli cell signaling. Am J Physiol Endocrinol Metab 2009; 296:E1022-8. [PMID: 19293333 DOI: 10.1152/ajpendo.90941.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have characterized the in vivo actions of human wild-type FSH receptor (FSHR) overexpressed in Sertoli cells of transgenic (Tg) mice (TgFSHRwt) compared with transgenic overexpression of the human activated mutant FSHR*D567G (TgFSHR*D567G). Testicular TgFSHRwt expression significantly elevated specific FSH binding (>2-fold, P < 0.01) relative to nontransgenic testes, similar to increased FSH binding in TgFSHR*D567G testes. Isolated TgFSHRwt Sertoli cells exhibited higher FSH-stimulated cAMP levels compared with non-Tg or TgFSHR*D567G cells but did not display the elevated FSH-independent basal cAMP levels found in TgFSHR*D567G Sertoli cells. Furthermore, Sertoli cell overexpression of TgFSHR*D567G but not TgFSHRwt allowed promiscuous cAMP responses to human chorionic gonadotropin (300 IU/ml) and TSH (30 mIU/ml), demonstrating increased constitutive signaling and altered glycoprotein hormone specificity via the intracellular D567G substitution rather than FSHR overexpression. Despite elevating Sertoli cell FSH sensitivity, overexpression of TgFSHRwt had no detectable effect upon normal testis function and did not stimulate Sertoli and germ cell development in testes of gonadotropin-deficient hypogonadal (hpg) mice, in contrast to the increased meiotic and postmeiotic germ cell development in TgFSHR*D567G hpg testes. Increased steroidogenic potential of TgFSHR*D567G hpg testes was demonstrated by elevated Cyp11a1 and Star expression, which was not detected in TgFSHRwt hpg testes. Androgen-regulated and Sertoli cell-specific Rhox5 gene expression was increased in TgFSHR*D567G but not TgFSHRwt hpg testes, providing evidence of elevated LH-independent androgen activity due to mutant FSHR*D567G. Hence, transgenic FSHR overexpression in Sertoli cells revealed that the D567G mutation confers autonomous signaling and steroidogenic activity in vivo as well as promiscuous glycoprotein hormone receptor activation, independently of FSHR overexpression alone.
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Affiliation(s)
- Charles M Allan
- ANZAC Research Institute, Concord Hospital, Sydney NSW 2139, Australia.
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21
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Tao YX. Constitutive activation of G protein-coupled receptors and diseases: insights into mechanisms of activation and therapeutics. Pharmacol Ther 2008; 120:129-48. [PMID: 18768149 DOI: 10.1016/j.pharmthera.2008.07.005] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 07/22/2008] [Indexed: 01/17/2023]
Abstract
The existence of constitutive activity for G protein-coupled receptors (GPCRs) was first described in 1980s. In 1991, the first naturally occurring constitutively active mutations in GPCRs that cause diseases were reported in rhodopsin. Since then, numerous constitutively active mutations that cause human diseases were reported in several additional receptors. More recently, loss of constitutive activity was postulated to also cause diseases. Animal models expressing some of these mutants confirmed the roles of these mutations in the pathogenesis of the diseases. Detailed functional studies of these naturally occurring mutations, combined with homology modeling using rhodopsin crystal structure as the template, lead to important insights into the mechanism of activation in the absence of crystal structure of GPCRs in active state. Search for inverse agonists on these receptors will be critical for correcting the diseases cause by activating mutations in GPCRs. Theoretically, these inverse agonists are better therapeutics than neutral antagonists in treating genetic diseases caused by constitutively activating mutations in GPCRs.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, 212 Greene Hall, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
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22
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Eglen RM, Bosse R, Reisine T. Emerging concepts of guanine nucleotide-binding protein-coupled receptor (GPCR) function and implications for high throughput screening. Assay Drug Dev Technol 2007; 5:425-51. [PMID: 17638542 DOI: 10.1089/adt.2007.062] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Guanine nucleotide binding protein (G protein) coupled receptors (GPCRs) comprise one of the largest families of proteins in the human genome and are a target for 40% of all approved drugs. GPCRs have unique structural motifs that allow them to interact with a wide and diverse series of extracellular ligands, as well as intracellular proteins, G proteins, receptor activity-modifying proteins, arrestins, and indeed other receptors. This distinctive structure has led to numerous efforts to discover drugs against GPCRs with targeted therapeutic uses. Such "designer" drugs currently include allosteric regulators, inverse agonists, and drugs targeting hetero-oligomeric complexes. Moreover, the large family of orphan GPCRs provides a rich and novel field of targets to discover drugs with unique therapeutic properties. The numerous technologies to discover GPCR drugs have also greatly advanced over the years, facilitating compound screening against known and orphan GPCRs, as well as in the identification of unique designer GPCR drugs. Indeed, high throughput screening (HTS) technologies employing functional cell-based approaches are now widely used. These include measurement of second messenger accumulation such as cyclic AMP, calcium ions, and inositol phosphates, as well as mitogen-activated protein kinase activation, protein-protein interactions, and GPCR oligomerization. This review focuses on how the improved understanding of the molecular pharmacology of GPCRs, coupled with a plethora of novel HTS technologies, is leading to the discovery and development of an entirely new generation of GPCR-based therapeutics.
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Affiliation(s)
- Richard M Eglen
- Discovery and Research Reagents, PerkinElmer Life and Analytical Sciences, Waltham, MA 02451, USA.
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23
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Kobilka BK, Deupi X. Conformational complexity of G-protein-coupled receptors. Trends Pharmacol Sci 2007; 28:397-406. [PMID: 17629961 DOI: 10.1016/j.tips.2007.06.003] [Citation(s) in RCA: 522] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 05/23/2007] [Accepted: 06/26/2007] [Indexed: 10/23/2022]
Abstract
G-protein-coupled receptors (GPCRs) are remarkably versatile signaling molecules. Members of this large family of membrane proteins respond to structurally diverse ligands and mediate most transmembrane signal transduction in response to hormones and neurotransmitters, and in response to the senses of sight, smell and taste. Individual GPCRs can signal through several G-protein subtypes and through G-protein-independent pathways, often in a ligand-specific manner. This functional plasticity can be attributed to structural flexibility of GPCRs and the ability of ligands to induce or to stabilize ligand-specific conformations. Here, we review what has been learned about the dynamic nature of the structure and mechanism of GPCR activation, primarily focusing on spectroscopic studies of purified human beta2 adrenergic receptor.
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Affiliation(s)
- Brian K Kobilka
- Stanford University School of Medicine, 157 Beckman Center, 279 Campus Drive, Stanford, CA 94305, USA.
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24
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Zhang M, Tao YX, Ryan GL, Feng X, Fanelli F, Segaloff DL. Intrinsic differences in the response of the human lutropin receptor versus the human follitropin receptor to activating mutations. J Biol Chem 2007; 282:25527-39. [PMID: 17609213 DOI: 10.1074/jbc.m703500200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In contrast to the human lutropin receptor (hLHR), very few naturally occurring activating mutations of the structurally related human follitropin receptor (hFSHR) have been identified. The present study was undertaken to determine if one aspect underlying this discrepancy might be a general resistance of the hFSHR to mutation-induced constitutive activity. Five different mutations were introduced into both the hLHR and hFSHR (four based on activating mutations of the hLHR gene, one based on an activating mutation of the hFSHR gene). Our results demonstrate that hFSHR constitutively activating mutants (CAMs) were not as active as hLHR CAMs containing the comparable mutation. Furthermore, although all hFSHR CAMs exhibited strong promiscuous activation by high concentrations of the other glycoprotein hormone receptors, hLHR CAMs showed little or no promiscuous activation. Our in vitro findings are consistent with in vivo observations of known pathophysiological conditions associated with hLHR CAMs, but not hFSHR CAMs, and with promiscuous activation of hFSHR CAMs, but not hLHR CAMs. Computational experiments suggest that the mechanisms through which homologous mutations increase the basal activity of the hLHR and the hFSHR are similar. This is particularly true for the strongest CAMs like L460(3.43)R. Disparate properties of the hLHR versus hFSHR CAMs may, therefore, be due to differences in shape and electrostatics features of the solvent-exposed cytosolic receptor domains involved in the receptor-G protein interface rather than to differences in the nature of local perturbation at the mutation site or in the way local perturbation is transferred to the putative G protein binding domains.
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Affiliation(s)
- Meilin Zhang
- Department of Molecular Physiology and Biophysics, the University of Iowa Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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25
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Ulloa-Aguirre A, Uribe A, Zariñán T, Bustos-Jaimes I, Pérez-Solis MA, Dias JA. Role of the intracellular domains of the human FSH receptor in G(alphaS) protein coupling and receptor expression. Mol Cell Endocrinol 2007; 260-262:153-62. [PMID: 17045734 PMCID: PMC1782136 DOI: 10.1016/j.mce.2005.11.050] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 11/15/2005] [Indexed: 11/18/2022]
Abstract
The human (h) follicle-stimulating hormone receptor (FSHR) belongs to the superfamily of G protein-coupled receptors (GPCRs). This receptor consists of 695 amino acid residues and is preferentially coupled to the G(s) protein. This receptor is highly conserved among species (overall homology, 85%), with a 25-69% homology drop when compared to the human LH and TSH receptors. Although studies in prototypical rhodopsin/beta-adrenergic receptors suggest that multiple domains in the intracellular loops (iL) and the carboxyl-terminus (Ctail) of these receptors contribute to G protein coupling and receptor expression, there is a paucity of structure/function data on the role of these domains in FSHR function. Employing point mutations we have found that several residues present in the iL2 of the hFSHR are important for both coupling the receptor to the G(s) protein and maintaining the receptor molecule in an inactive conformation. In fact, HEK-293 cells expressing several hFSHR mutants with substitutions at R(450) (central to the highly conserved ERW triplet motif) and T(453) (a potential target for phosphorylation) failed to mediate ligand-provoked G(s) protein activation but not agonist binding, whereas substitutions at the hydrophobic L(460) (a conserved residue present in all glycoprotein hormone receptors) conferred elevated basal cAMP to the transfected cells. Thus, this particular loop apparently acts as a conformational switch for allowing the receptor to adopt an active conformation upon agonist stimulation. Residues in both ends of the iL3 are important for signal transduction in a number of GPCRs, including the FSHR. We have recently explored the importance of the reversed BBXXB motif (BXXBB; where B represents a basic residue and X a non-basic residue) present in the juxtamembrane region of the hFSHR iL3. A hFSHR mutant with all basic amino acids present in the iL3 BXXBB motif replaced by alanine failed to bind agonist and activate effector, and was expressed as an immature < or =62kDa form of the receptor. Individual substitutions of basic residues resulted in mutants that bound agonist normally but failed to activate effector when replaced at R(552) or R(556). Triple mutations in the same motif located in the NH(2)-end of the Ctail resulted in a complete inability of the receptor to bind agonist and activate effector, whereas individual substitutions resulted in decreased or virtually abolished agonist binding and cAMP accumulation, with both functions correlating with the detected levels of mature (80kDa) forms of the receptor. Thus, the BXXBB motif at the iL3 of the FSHR is essential for coupling the activated receptor to the G(s) protein, whereas the same motif in the Ctail is apparently more important for membrane expression. The role of cysteine residues present in the Ctail of the FSHR is an enigma since there are no conserved cysteines amongst LHR, FSHR and TSHR. C(629) and C(655) are conserved in the gonadotropin receptors but not in the TSHR. Alanine replacement of C(627) had no effect on hFSHR expression and function, whereas the same mutation at C(629) altered membrane expression and signal transduction. Serine or threonine substitutions of C(655) did not modify any of the parameters analyzed. In the hFSHR, C(629) may be a target for palmitoylation, and apparently it is the only cysteine residue in the Ctail domain that might play an important role in receptor function.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia Luis Castelazo Ayala, Instituto Mexicano del Seguro Social, Apartado Postal 99-065, Unidad Independencia, México 10101 D.F., Mexico.
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26
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Abstract
G protein-coupled receptors (GPCRs) mediate responses to hormones and neurotransmitters, as well as the senses of sight, smell, and taste. These remarkably versatile signaling molecules respond to structurally diverse ligands. Many GPCRs couple to multiple G protein subtypes, and several have been shown to activate G protein-independent signaling pathways. Drugs acting on GPCRs exhibit efficacy profiles that may differ for different signaling cascades. The functional plasticity exhibited by GPCRs can be attributed to structural flexibility and the existence of multiple ligand-specific conformational states. This chapter will review our current understanding of the mechanism by which agonists bind and activate GPCRs.
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Affiliation(s)
- Xavier Deupi
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA
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27
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Bonomi M, Busnelli M, Persani L, Vassart G, Costagliola S. Structural Differences in the Hinge Region of the Glycoprotein Hormone Receptors: Evidence from the Sulfated Tyrosine Residues. Mol Endocrinol 2006; 20:3351-63. [PMID: 16901970 DOI: 10.1210/me.2005-0521] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Tyrosine sulfation is a late posttranslational modification of proteins that takes place in the Golgi network. In the past few years, this process has been identified as an important modulator of protein-protein interactions. Sulfated tyrosine residues have recently been identified in the C-terminal, so-called hinge region of the ectodomain of glycoprotein hormone receptors [TSH, LH/chorionic gonadotropin (CG), and FSH receptors] and were shown to play an important role in the interaction with their natural ligands. The position of two sulfated tyrosine residues in a Y-D/E-Y motif appears perfectly conserved in the alignment of TSH and LH receptors from different species, and site-directed mutagenesis experiments demonstrated that sulfation of the first residue of this motif was responsible for the functional effect on hormone binding. In contrast, the corresponding motif is not conserved in the FSH receptor, in which the first tyrosine residue is missing: the Y-D/E-Y motif is replaced by F(333)DY(335). We extend here our previous observation that, in this case, it is sulfation of the second sole tyrosine residue in the motif that is functionally important. An LH/CG receptor harboring an F(331)DY(333) motif (i.e. displaying decreased sensitivity to human CG) was used as a backbone in which short portions of the FSH receptor were substituted. Segments from the FSH receptor capable of restoring sensitivity to human CG were identified by transfection of the chimeras in COS-7 cells. These experiments identified key amino acid residues in the hinge region of the FSH receptor associated with the functional role of the second sulfated tyrosine residue in a Y-D/E-Y motif, allowing for efficient hormone binding. The experiments represent strong evidence that structural differences in the hinge regions of FSH and LH/CG receptors play a significant role in hormone-receptor-specific recognition.
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Affiliation(s)
- Marco Bonomi
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Belgium.
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28
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Geiser AH, Sievert MK, Guo LW, Grant JE, Krebs MP, Fotiadis D, Engel A, Ruoho AE. Bacteriorhodopsin chimeras containing the third cytoplasmic loop of bovine rhodopsin activate transducin for GTP/GDP exchange. Protein Sci 2006; 15:1679-90. [PMID: 16815918 PMCID: PMC2265101 DOI: 10.1110/ps.062192306] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The mechanisms by which G-protein-coupled receptors (GPCRs) activate G-proteins are not well understood due to the lack of atomic structures of GPCRs in an active form or in GPCR/G-protein complexes. For study of GPCR/G-protein interactions, we have generated a series of chimeras by replacing the third cytoplasmic loop of a scaffold protein bacteriorhodopsin (bR) with various lengths of cytoplasmic loop 3 of bovine rhodopsin (Rh), and one such chimera containing loop 3 of the human beta2-adrenergic receptor. The chimeras expressed in the archaeon Halobacterium salinarum formed purple membrane lattices thus facilitating robust protein purification. Retinal was correctly incorporated into the chimeras, as determined by spectrophotometry. A 2D crystal (lattice) was evidenced by circular dichroism analysis, and proper organization of homotrimers formed by the bR/Rh loop 3 chimera Rh3C was clearly illustrated by atomic force microscopy. Most interestingly, Rh3C (and Rh3G to a lesser extent) was functional in activation of GTPgamma35S/GDP exchange of the transducin alpha subunit (Galphat) at a level 3.5-fold higher than the basal exchange. This activation was inhibited by GDP and by a high-affinity peptide analog of the Galphat C terminus, indicating specificity in the exchange reaction. Furthermore, a specific physical interaction between the chimera Rh3C loop 3 and the Galphat C terminus was demonstrated by cocentrifugation of transducin with Rh3C. This Galphat-activating bR/Rh chimera is highly likely to be a useful tool for studying GPCR/G-protein interactions.
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Affiliation(s)
- Andrew H Geiser
- Department of Pharmacology, University of Wisconsin Medical School, Madison 53706, USA
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29
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Allan CM, Garcia A, Spaliviero J, Jimenez M, Handelsman DJ. Maintenance of Spermatogenesis by the Activated Human (Asp567Gly) FSH Receptor During Testicular Regression Due to Hormonal Withdrawal1. Biol Reprod 2006; 74:938-44. [PMID: 16452461 DOI: 10.1095/biolreprod.105.048413] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The first activating mutation of the FSH receptor (FSHR*D567G) was identified in a gonadotropin-deficient hypophysectomized man who exhibited persistent spermatogenesis and fertility with only androgen replacement. We have determined the ability of FSHR* activity to maintain spermatogenesis and/or steroidogenesis during gonadotropin and androgen deprivation in mature transgenic FSHR* mice (Tg(Abpa-FSHR*D567G)1Cmal), hereafter referred to as Tg-FSHR* mice. Testes of untreated adult Tg-FSHR* males were equivalent in weight to nontransgenic controls but exhibited increased total Sertoli cell (24%) and spermatogonia (34%) numbers and nonsignificantly elevated spermatocyte-spermatid numbers (13%-17%). During sustained GNRH1 agonist treatment that markedly reduced (96%-98%) serum LH and testosterone (T) and decreased serum FSH (68%-72%), the testes of GNRH1 agonist-treated Tg-FSHR* mice remained significantly larger than treated nontransgenic controls. After 4 wk of gonadotropin suppression, Sertoli cell numbers were reduced in Tg-FSHR* testes to levels comparable with nontransgenic testes, whereas spermatogonia numbers were maintained at higher levels relative to nontransgenic testes. However, after 8 wk of GNRH1 agonist treatment, the total spermatogonia, spermatocyte, or postmeiotic spermatid numbers were reduced to equivalent levels in Tg-FSHR* and nontransgenic mice. FSHR* effects were further examined in gonadotropin-deficient hypogonadal Gnrh1hpg/Gnrh1hpg (Gnrh1(-/-)) mice during testicular regression following withdrawal of T after maximal T-stimulated spermatogenesis. After 6 wk of T withdrawal, spermatogonia, spermatocyte, and postmeiotic spermatid numbers in Tg-FSHR* Gnrh1(-/-) testes decreased to levels found in untreated Tg-FSHR* Gnrh1(-/-) testes. Basal serum T levels in untreated Tg-FSHR* Gnrh1(-/-) males were 2-fold higher than Gnrh1(-/-) controls, but following T treatment/withdrawal, serum T and epididymal weights declined to basal levels found in nontransgenic Gnrh1(-/-) mice. Therefore, FSHR* was unable to sustain circulating T or androgen-dependent epididymal size or postmeiotic spermatogenic development. We conclude that FSHR* activity enhances Sertoli and spermatogenic development in normal testes but has limited ability to maintain spermatogenesis during gonadotropin deficiency, in which the testicular response provided by the FSHR*D567G mutation resembled typical FSH-mediated but not steroidogenic activity.
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Affiliation(s)
- Charles M Allan
- Andrology Laboratory, University of Sydney, ANZAC Research Institute, Concord Hospital, Sydney, New South Wales 2139, Australia.
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30
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Kenakin T. Testing for inverse agonism with constitutive receptor systems. ACTA ACUST UNITED AC 2006; Chapter 9:Unit9.5. [PMID: 22294179 DOI: 10.1002/0471141755.ph0905s32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This unit discusses the use of constitutive 7-transmembrane/G protein coupled receptor (7TM/GPCR) activity for screening new drug entities. Following an introduction to constitutive 7TM/GPCR activity, the unit centers on the three basic components of a constitutive screening system: the receptor, the receptor coupling components (G protein), and the response reporting system. The design of specific assays to detect inverse agonism and the application of such systems to drug screening are also discussed. Finally, the relative advantages and disadvantages of inverse agonists as therapeutic agents are considered.
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Affiliation(s)
- Terry Kenakin
- GlaxoSmithKline Research and Development, Research Triangle Park, North Carolina, USA
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31
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Timossi C, Ortiz-Elizondo C, Pineda DB, Dias JA, Conn PM, Ulloa-Aguirre A. Functional significance of the BBXXB motif reversed present in the cytoplasmic domains of the human follicle-stimulating hormone receptor. Mol Cell Endocrinol 2004; 223:17-26. [PMID: 15279907 DOI: 10.1016/j.mce.2004.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Revised: 05/31/2004] [Accepted: 06/09/2004] [Indexed: 10/26/2022]
Abstract
The minimal structural motif, BBXXB (where B represents a basic amino acid residue and X a non-basic residue), located in particular regions of the intracellular domains of cell surface membrane receptors is involved in the G protein-activating activity of a number of G protein-coupled receptors. The human FSH receptor (hFSHR) exhibits a reversed BBXXB motif (BXXBB) in the juxtamembrane region of the third intracellular loop (IL3) and the carboxyl terminus (Ctail) of the receptor; however the importance of this sequence on receptor function remains unclear. In the present study, we analyzed the effects of mutations in this structural motif on hFSHR expression, receptor-mediated effector activation and agonist-provoked receptor internalization. Human embryonic kidney 293 cells were transiently transfected with plasmids containing the cDNA of the wild-type (Wt) hFSHR or several hFSHR mutants in which basic amino acids of the minimal structural motif at the IL3 and Ctail were replaced with alanine (i.e. AXXAA, AXXBB, BXXAB and BXXBA mutants). Alanine substitution of the three basic residues present in the IL3-BXXBB (IL3-AXXAA mutant) yielded a < or =60 kDa possibly under-glycosylated form of the FSHR, whereas the same substitutions in the Ctail resulted in the immature >62 kDa form of the receptor; both AXXAA hFSHR mutants completely failed to bind agonist and activate effector. Individual substitutions resulted in different cAMP responses to agonist stimulation: the IL3-AXXBB and IL3-BXXBA mutant hFSHRs failed to evoke Gs protein activation, whereas agonist-stimulated cAMP production was completely normal when the IL3-BXXAB mutant was expressed. All three IL3 mutants bound [125I]-labelled FSH in a similar fashion to the Wt hFSHR. Ligand-binding, cell surface membrane receptor expression and agonist-provoked effector activation were significantly affected by the individual substitutions at the Ctail-BXXBB motif: the Ctail-AXXBB variant exhibited reduced (approximately 50%) maximal cAMP response and ability to bind ligand, whereas both ligand binding and effector activation was severely reduced or abolished by expression of the Ctail-BXXBA and -BXXAB hFSHR mutants; the expression levels of the 80 kDa form of the receptor correlated with the magnitude of ligand-provoked cAMP production and binding capability of the mutant receptors. Upon stimulation by agonist, all mutants with detectable ligand-binding activity internalized following the pattern exhibited by the Wt hFSHR species. These results indicate that the BXXBB motif at the IL3 of the hFSHR is essential for coupling the activated receptor to the Gs protein, whereas the same motif in the Ctail is apparently more important for membrane expression.
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Affiliation(s)
- Carlos Timossi
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia Luis Castelazo Ayala, Instituto Mexicano del Seguro Social, Apartado Postal 99-065, Unidad Independencia, México 10101, D.F., Mexico
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32
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Roh J, Virtanen H, Kumagai J, Sudo S, Kaleva M, Toppari J, Hsueh AJW. Lack of LGR8 gene mutation in Finnish patients with a family history of cryptorchidism. Reprod Biomed Online 2004; 7:400-6. [PMID: 14656401 DOI: 10.1016/s1472-6483(10)61883-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Cryptorchidism is the most frequent congenital anomaly of the urogenital tract in the male. Although in Western countries 1-2% of males at the age of 3 months are diagnosed with this condition, its aetiology is still unknown. Animal models suggest a possible genetic basis for this disorder. Recently, the INSL3 (Leydig insulin-like peptide) gene and its cognate receptor, LGR8, were found to be important in testicular descent by regulating gubernacular development. Male mice null for either INSL3 or LGR8 genes exhibited bilateral cryptorchidism. Because earlier studies indicated that mutation of the INSL3 gene is not associated with the development of human cryptorchidism, this study analysed whether mutations in the LGR8 gene could be associated with this disorder. Sequencing of 18 exons of the LGR8 gene in 23 cryptorchid Finnish patients and a group of 33 control subjects allowed the identification of three nucleotide changes in exons 12 and 17, showing single base substitutions from A to G at positions 957, 993, and 1810 of LGR8. Among the three changes, only the 1810 A to G substitution is associated with an amino acid change from isoleucine to valine (Ile604Val) located in the fifth transmembrane domain of this seven-transmembrane receptor. This change was more frequent in a control group of normal fertile adult males and infant boys than in the group of cryptorchid males. The change is not associated with altered receptor signalling, thus suggesting the presence of a polymorphism unrelated to the cryptorchid phenotype. These data indicate that mutations involving the human LGR8 gene do not represent a frequent cause of cryptorchidism in the Finnish population.
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Affiliation(s)
- Jaesook Roh
- Division of Reproductive Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA 94305-5317, USA
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33
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Yin D, Gavi S, Wang HY, Malbon CC. Probing receptor structure/function with chimeric G-protein-coupled receptors. Mol Pharmacol 2004; 65:1323-32. [PMID: 15155825 DOI: 10.1124/mol.65.6.1323] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Owing its name to an image borrowed from Greek mythology, a chimera is seen to represent a new entity created as a composite from existing creatures or, in this case, molecules. Making use of various combinations of three basic domains of the receptors (i.e., exofacial, transmembrane, and cytoplasmic segments) that couple agonist binding into activation of effectors through heterotrimeric G-proteins, molecular pharmacology has probed the basic organization, structure/function relationships of this superfamily of heptahelical receptors. Chimeric G-protein-coupled receptors obviate the need for a particular agonist ligand when the ligand is resistant to purification or, in the case of orphan receptors, is not known. Chimeric receptors created from distant members of the heptahelical receptors enable new strategies in understanding how these receptors transduce agonist binding into receptor activation and may be able to offer insights into the evolution of G-protein-coupled receptors from yeast to humans.
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Affiliation(s)
- Dezhong Yin
- Department of Molecular Pharmacology, University Medical Center, Stony Brook University, Stony Brook, New York, USA
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Montanelli L, Van Durme JJJ, Smits G, Bonomi M, Rodien P, Devor EJ, Moffat-Wilson K, Pardo L, Vassart G, Costagliola S. Modulation of ligand selectivity associated with activation of the transmembrane region of the human follitropin receptor. Mol Endocrinol 2004; 18:2061-73. [PMID: 15166252 DOI: 10.1210/me.2004-0036] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recently, three naturally occurring mutations in the serpentine region of the FSH receptor (FSHr) (D567N and T449I/A) have been identified in three families with spontaneous ovarian hyperstimulation syndrome (OHSS). All mutant receptors displayed abnormally high sensitivity to human chorionic gonadotropin and, in addition, D567N and T449A displayed concomitant increase in sensitivity to TSH and detectable constitutive activity. In the present study, we have used a combination of site-directed mutagenesis experiments and molecular modeling to explore the mechanisms responsible for the phenotype of the three OHSS FSHr mutants. Our results suggest that all mutations lead to weakening of interhelical locks between transmembrane helix (TM)-VI and TM-III, or TM-VI and TM-VII, which contributes to maintaining the receptor in the inactive state. They also indicate that broadening of the functional specificity of the mutant FSHr constructs is correlated to their increase in constitutive activity. This relation between basal activity and functional specificity is a characteristic of the FSHr, which is not shared by the other glycoprotein hormone receptors. It leads to the interesting suggestion that different pathways have been followed during primate evolution to avoid promiscuous stimulation of the TSHr and FSHr by human chorionic gonadotropin. In the hFSHr, specificity would be exerted both by the ectodomain and the serpentine portion.
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Affiliation(s)
- Lucia Montanelli
- IRIBHM, Université Libre de Bruxelles, Campus Erasme, Route de Lennik 808, B-1070 Brussels
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Sudo S, Avsian-Kretchmer O, Wang LS, Hsueh AJW. Protein Related to DAN and Cerberus Is a Bone Morphogenetic Protein Antagonist That Participates in Ovarian Paracrine Regulation. J Biol Chem 2004; 279:23134-41. [PMID: 15039429 DOI: 10.1074/jbc.m402376200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Bone morphogenetic proteins (BMPs) are important for body patterning and morphogenesis, whereas several BMP antagonists regulate the functions of BMPs during embryonic development and tissue differentiation. Protein related to DAN and cerberus (PRDC) is a secreted protein with a cystine knot structure identified by gene trapping in embryonic stem cells. Although PRDC shows sequence homology with proteins of the BMP antagonist family, its biological activity and physiological functions are unclear. We generated recombinant PRDC and its paralog, gremlin, and tested their ability to suppress actions initiated by diverse BMP proteins. Similar to the known BMP antagonist, gremlin, PRDC blocked ligand signaling induced by BMP2 and BMP4 but had minimal effects on reporter gene activation induced by GDF-9, activin, or transforming growth factor-beta. Co-precipitation assays further demonstrated the direct protein-protein interactions between PRDC and BMP2 or BMP4. Reverse transcriptase-PCR analyses indicated that PRDC transcripts are widely expressed showing higher levels in ovary, brain, and spleen. In mouse ovary, PRDC transcripts were increased following gonadotropin treatment. In situ hybridization analyses further indicated that ovarian PRDC transcripts are localized in granulosa cells of selective follicles. In addition, co-treatment with PRDC antagonized the inhibitory effects of BMP4 on the follicle-stimulating hormone stimulation of progesterone production by cultured rat granulosa cells. Thus, PRDC is a potent BMP antagonist with a wide tissue expression pattern, and ovarian PRDC expressed in granulosa cells could be involved in follicular development by antagonizing the actions of theca cell-derived BMPs.
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Affiliation(s)
- Satoko Sudo
- Division of Reproductive Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California 94305-5317, USA
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Madabushi S, Gross AK, Philippi A, Meng EC, Wensel TG, Lichtarge O. Evolutionary trace of G protein-coupled receptors reveals clusters of residues that determine global and class-specific functions. J Biol Chem 2003; 279:8126-32. [PMID: 14660595 DOI: 10.1074/jbc.m312671200] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptor (GPCR) activation mediated by ligand-induced structural reorganization of its helices is poorly understood. To determine the universal elements of this conformational switch, we used evolutionary tracing (ET) to identify residue positions commonly important in diverse GPCRs. When mapped onto the rhodopsin structure, these trace residues cluster into a network of contacts from the retinal binding site to the G protein-coupling loops. Their roles in a generic transduction mechanism were verified by 211 of 239 published mutations that caused functional defects. When grouped according to the nature of the defects, these residues sub-divided into three striking sub-clusters: a trigger region, where mutations mostly affect ligand binding, a coupling region near the cytoplasmic interface to the G protein, where mutations affect G protein activation, and a linking core in between where mutations cause constitutive activity and other defects. Differential ET analysis of the opsin family revealed an additional set of opsin-specific residues, several of which form part of the retinal binding pocket, and are known to cause functional defects upon mutation. To test the predictive power of ET, we introduced novel mutations in bovine rhodopsin at a globally important position, Leu-79, and at an opsin-specific position, Trp-175. Both were functionally critical, causing constitutive G protein activation of the mutants and rapid loss of regeneration after photobleaching. These results define in GPCRs a canonical signal transduction mechanism where ligand binding induces conformational changes propagated through adjacent trigger, linking core, and coupling regions.
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Affiliation(s)
- Srinivasan Madabushi
- Program in Structural and Computational Biology and Molecular Biophysics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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Chakir K, Xiang Y, Yang D, Zhang SJ, Cheng H, Kobilka BK, Xiao RP. The third intracellular loop and the carboxyl terminus of beta2-adrenergic receptor confer spontaneous activity of the receptor. Mol Pharmacol 2003; 64:1048-58. [PMID: 14573753 DOI: 10.1124/mol.64.5.1048] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
It is well established that the beta2-adrenergic receptor (beta2-AR) exhibits a robust ligand-independent activity, whereas this property is considerably weaker in the closely related beta1-AR subtype. To identify the potential domain(s) of beta2-AR responsible for the spontaneous receptor activation, we created three chimeras in which the third intracellular loop (beta1/beta2-Li3) or the carboxyl terminus (beta1/beta2-CT) or both domains (beta1/beta2-Li3CT) of beta1-AR are replaced by the corresponding parts of the beta2-AR. Using adenoviral gene transfer, we individually expressed these beta1/beta2-AR chimeras in mouse cardiomyocytes lacking both native beta1-AR and beta2-AR (beta1/beta2 double knockout), and examined their possible spontaneous activities. Overexpression of these beta1/beta2-AR chimeras markedly elevated basal cAMP accumulation and myocyte contractility in the absence of agonist stimulation compared with those infected by a control adenovirus expressing beta-galactosidase or an adenovirus expressing wild type beta1-AR. These effects were fully reversed by a beta2-AR inverse agonist, (+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol (ICI 118,551; 5 x 10-7 M), regardless of inhibition of Gi with pertussis toxin, but not by a panel of beta1-AR antagonists, including [2-(3-carbamoyl-4-hydroxyphenoxy)-ethylamino]-3-[4-(1-methyl-4-trifluormethyl-2-imidazolyl)-phenoxy]-2-propanolmethanesulfonate (CGP20712A), betaxolol, bisoprolol, and metoprolol. Furthermore, we have shown that the C-terminal postsynaptic density 95/disc-large/ZO-1 (PDZ) motif of beta1-AR is not responsible for the lack of beta1-AR spontaneous activation, although it has been known that the beta1-AR PDZ motif prevents the receptor from undergoing agonist-induced trafficking and Gi coupling in cardiomyocytes. Taken together, the present results indicate that both the third intracellular loop and the C terminus are involved in beta2-AR spontaneous activation and that either domain seems to be sufficient to confer the receptor spontaneous activity.
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MESH Headings
- Adrenergic beta-Antagonists/pharmacology
- Animals
- Cells, Cultured
- Cyclic AMP/metabolism
- Imidazoles/pharmacology
- Isoproterenol/pharmacology
- Mice
- Myocardial Contraction/drug effects
- Myocardium/metabolism
- Propanolamines/pharmacology
- Protein Conformation
- Protein Structure, Tertiary
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Recombinant Fusion Proteins
- Signal Transduction/physiology
- Subcellular Fractions
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Affiliation(s)
- Khalid Chakir
- Laboratory of Cardiovascular Science, Gerontology Research Center, NIA, NIH, 5600 Nathan Shock Dr., Baltimore, MD 21224, USA
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Nakabayashi K, Kudo M, Hsueh AJW, Maruo T. Activation of the luteinizing hormone receptor in the extracellular domain. Mol Cell Endocrinol 2003; 202:139-44. [PMID: 12770743 DOI: 10.1016/s0303-7207(03)00075-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Glycoprotein hormone receptors have ligand-binding ectodomains consisting of leucine-rich repeats, followed by a conserved cysteine-rich hinge region to the seven transmembrane (TM) region. Based on constitutively active mutations at Ser-281 in the hinge region of the thyroid-stimulating hormone receptor, we mutated the conserved serine in the luteinizing hormone (LH) receptor (S277I) and observed increased basal cAMP production and ligand affinity by mutant receptor. Conversion of Ser-277 to all natural amino acids led to varying degrees of receptor activation. Hydropathy index analysis indicated that substitution of neutral serine with selective nonpolar hydrophobic residues (Leu>Val>Met>Ile) confers constitutive receptor activation. Furthermore, mutation of the angular proline near Ser-273 to flexible Gly also led to receptor activation. The findings suggest the ectodomain of LH receptor constrains the TM region. Point mutations in the hinge region or ligand binding could cause conformational changes in the TM region that result in Gs activation.
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Affiliation(s)
- Koji Nakabayashi
- Division of Reproductive Biology, Department of Gynecology and Obstetrics, Stanford University School of Medicine, Stanford, CA, USA.
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40
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Sudo S, Kumagai J, Nishi S, Layfield S, Ferraro T, Bathgate RAD, Hsueh AJW. H3 relaxin is a specific ligand for LGR7 and activates the receptor by interacting with both the ectodomain and the exoloop 2. J Biol Chem 2003; 278:7855-62. [PMID: 12506116 DOI: 10.1074/jbc.m212457200] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leucine-rich repeat-containing, G protein-coupled receptors (LGRs) represent a unique subgroup of G protein-coupled receptors with a large ectodomain. Recent studies demonstrated that relaxin activates two orphan LGRs, LGR7 and LGR8, whereas INSL3/Leydig insulin-like peptide specifically activates LGR8. Human relaxin 3 (H3 relaxin) was recently discovered as a novel ligand for relaxin receptors. Here, we demonstrate that H3 relaxin activates LGR7 but not LGR8. Taking advantage of the overlapping specificity of these three ligands for the two related LGRs, chimeric receptors were generated to elucidate the mechanism of ligand activation of LGR7. Chimeric receptor LGR7/8 with the ectodomain from LGR7 but the transmembrane region from LGR8 maintains responsiveness to relaxin but was less responsive to H3 relaxin based on ligand stimulation of cAMP production. The decreased ligand signaling was accompanied by decreases in the ability of H3 relaxin to compete for (33)P-relaxin binding to the chimeric receptor. However, replacement of the exoloop 2, but not exoloop 1 or 3, of LGR7 to the chimeric LGR7/8 restored ligand binding and receptor-mediated cAMP production. These results suggested that activation of LGR7 by H3 relaxin involves specific binding of the ligand to both the ectodomain and the exoloop 2, thus providing a model with which to understand the molecular basis of ligand signaling for this unique subgroup of G protein-coupled receptors.
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Affiliation(s)
- Satoko Sudo
- Division of Reproductive Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, California 94305-5317, USA
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41
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Haywood M, Tymchenko N, Spaliviero J, Koch A, Jimenez M, Gromoll J, Simoni M, Nordhoff V, Handelsman DJ, Allan CM. An activated human follicle-stimulating hormone (FSH) receptor stimulates FSH-like activity in gonadotropin-deficient transgenic mice. Mol Endocrinol 2002; 16:2582-91. [PMID: 12403847 DOI: 10.1210/me.2002-0032] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
FSH mediates its testicular actions via a specific Sertoli cell G protein-coupled receptor. We created a novel transgenic model to investigate a mutant human FSH receptor (FSHR(+)) containing a single amino acid substitution (Asp567Gly) equivalent to activating mutations in related glycoprotein hormone receptors. To examine the ligand-independent gonadal actions of FSHR(+), the rat androgen-binding protein gene promoter was used to direct FSHR(+) transgene expression to Sertoli cells of gonadotropin-deficient hypogonadal (hpg) mice. Both normal and hpg mouse testes expressed FSHR(+) mRNA. Testis weights of transgenic FSHR(+) hpg mice were increased approximately 2-fold relative to hpg controls (P < 0.02) and contained mature Sertoli cells and postmeiotic germ cells absent in controls, revealing FSHR(+)-initiated autonomous FSH-like testicular activity. Isolated transgenic Sertoli cells had significantly higher basal ( approximately 2-fold) and FSH-stimulated ( approximately 50%) cAMP levels compared with controls, demonstrating constitutive signaling and cell-surface expression of FSHR(+), respectively. Transgenic FSHR(+) also elevated testosterone production in hpg testes, in the absence of circulating LH (or FSH), and it was not expressed functionally on steroidogenic cells, suggesting a paracrine effect mediated by Sertoli cells. The FSHR(+) response was additive with a maximal testosterone dose on hpg testicular development, demonstrating FSHR(+) activity independent of androgen-specific actions. The FSHR(+) response was male specific as ovarian expression of FSHR(+) had no effect on hpg ovary size. These findings reveal transgenic FSHR(+) stimulated a constitutive FSH-like Sertoli cell response in gonadotropin-deficient testes, and pathways that induced LH-independent testicular steroidogenesis. This novel transgenic paradigm provides a unique approach to investigate the in vivo actions of mutated activating gonadotropin receptors.
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Affiliation(s)
- Miriam Haywood
- Andrology Laboratory, ANZAC Research Institute, Sydney, New South Wales 2139, Australia
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42
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Nakabayashi K, Matsumi H, Bhalla A, Bae J, Mosselman S, Hsu SY, Hsueh AJ. Thyrostimulin, a heterodimer of two new human glycoprotein hormone subunits, activates the thyroid-stimulating hormone receptor. J Clin Invest 2002. [DOI: 10.1172/jci0214340] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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43
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Nakabayashi K, Matsumi H, Bhalla A, Bae J, Mosselman S, Hsu SY, Hsueh AJW. Thyrostimulin, a heterodimer of two new human glycoprotein hormone subunits, activates the thyroid-stimulating hormone receptor. J Clin Invest 2002; 109:1445-52. [PMID: 12045258 PMCID: PMC150994 DOI: 10.1172/jci14340] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Human thyrotropin (TSH), luteotropin (LH), follitropin (FSH), and chorionic gonadotropin are members of the heterodimeric glycoprotein hormone family. The common alpha subunit forms noncovalent heterodimers with different beta subunits. Two novel human glycoprotein hormonelike genes, alpha2 (A2) and beta5 (B5), recently have been identified. Using a yeast two-hybrid assay, the two subunits were found as potential heterodimerization partners. Immunological analyses confirmed the heterodimerization of A2 and B5 in transfected cells and their colocalization in the anterior pituitary. Recombinant A2/B5 heterodimeric glycoproteins, purified using cation exchange and size fractionation chromatography, activated human TSH receptors, but not LH and FSH receptors, and showed high affinity to TSH receptors in a radioligand receptor assay. The heterodimer also stimulated cAMP production and thymidine incorporation by cultured thyroid cells and increased serum thyroxine levels in TSH-suppressed rats in vivo. This new heterodimeric glycoprotein hormone was named as thyrostimulin based on its thyroid-stimulating activity. The expression of thyrostimulin in the anterior pituitary known to express TSH receptors suggested a paracrine mechanism. The present discovery of a new ligand based on genomic approaches could facilitate the understanding of the physiological roles of extra-thyroid TSH receptor systems and the structural-functional basis of receptor signaling by related glycoprotein hormones.
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Affiliation(s)
- Koji Nakabayashi
- Division of Reproductive Biology, Department of Gynecology and Obstetrics, Stanford University School of Medicine, Stanford, California 94305-5317, USA
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44
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Mukherjee S, Gurevich VV, Preninger A, Hamm HE, Bader MF, Fazleabas AT, Birnbaumer L, Hunzicker-Dunn M. Aspartic acid 564 in the third cytoplasmic loop of the luteinizing hormone/choriogonadotropin receptor is crucial for phosphorylation-independent interaction with arrestin2. J Biol Chem 2002; 277:17916-27. [PMID: 11867621 DOI: 10.1074/jbc.m110479200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arrestin2 binding to the active but unphosphorylated luteinizing hormone/choriogonadotropin receptor (LH/CG R) in ovarian follicles is triggered by activation of ADP-ribosylation factor 6 (ARF6) and leads to uncoupling of this receptor from cAMP signaling. We sought to determine how arrestin2 binds to LH/CG R, if binding is of high affinity, and if the receptor also binds arrestin3. Desensitization of intact LH/CG R was equally sensitive to ectopic constructs of arrestin2 that bind other G protein-coupled receptors (GPCRs) either in a phosphorylation-independent or -dependent manner. Intact LH/CG R was not desensitized by ectopic arrestin3 constructs. Surface plasmon resonance studies showed that arrestin2 bound a synthetic third intracellular (3i) LH/CG R loop peptide with picomolar affinity; arrestin3 bound with millimolar affinity. To determine whether Asp-564 in the 3i loop mimicked the phosphorylated residue of other GPCRs, human embryonic kidney (HEK) cells were transfected with wild-type (WT) and D564G LH/CG R. An agonist-stimulated ARF6-dependent arrestin2 undocking pathway to drive desensitization of WT receptor was recapitulated in HEK cell membranes, and ectopic arrestin2 promoted desensitization of WT LH/CG R. However, D564G LH/CG R in HEK cells was not desensitized, and synthetic 3i D564G peptide did not bind arrestin2. Synthetic 3i loop peptides containing D564E, D564V, or D564N also did not bind arrestin2. We conclude that the ARF6-mediated mechanism to release a pool of membrane-delimited arrestin to bind GPCRs may be a widespread mechanism to deliver arrestin to GPCRs for receptor desensitization. Unlike other GPCRs that additionally require receptor phosphorylation, LH/CG R activation is sufficient to expose a conformation in which Asp-564 in the 3i loop confers high affinity binding selectively to arrestin2.
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Affiliation(s)
- Sutapa Mukherjee
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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45
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Dias JA, Cohen BD, Lindau-Shepard B, Nechamen CA, Peterson AJ, Schmidt A. Molecular, structural, and cellular biology of follitropin and follitropin receptor. VITAMINS AND HORMONES 2002; 64:249-322. [PMID: 11898394 DOI: 10.1016/s0083-6729(02)64008-7] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Follitropin and the follitropin receptor are essential for normal gamete development in males and females. This review discusses the molecular genetics and structural and cellular biology of the follitropin/follitropin receptor system. Emphasis is placed on the human molecules when possible. The structure and regulation of the genes for the follitropin beta subunit and the follitropin receptor is discussed. Control of systemic and cellular protein levels is explained. The structural biology of each protein is described, including protein structure, motifs, and activity relationships. Finally, the follitropin/follitropin receptor signal transduction system is discussed.
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Affiliation(s)
- James A Dias
- Wadsworth Center, David Axelrod Institute for Public Health, New York State Department of Health, Albany, New York 12208, USA
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46
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Abstract
Reproduction cannot take place without the proper functioning of the lutropin/choriogonadotropin receptor (LHR). When the LHR does not work properly, ovulation does not occur in females and Leydig cells do not develop normally in the male. Also, because the LHR is essential for sustaining the elevated levels of progesterone needed to maintain pregnancy during the first trimester, disruptions in the functions of the LHR during pregnancy have catastrophic consequences. As such, a full understanding of the biology of the LHR is essential to the survival of our species. In this review we summarize our current knowledge of the structure, functions, and regulation of this important receptor.
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Affiliation(s)
- Mario Ascoli
- Department of Pharmacology, The University of Iowa, Iowa City, 52242-1109, USA.
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47
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Ignacak M, Starzyk J, Dziatkowiak H, Trzeciak WH. Study of the family of a patient with male-limited precocious puberty (MPP) due to T1193C transition in exon 11 of LH receptor gene. J Endocrinol Invest 2002; 25:259-63. [PMID: 11936470 DOI: 10.1007/bf03344001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Molecular diagnostics of the LHR gene was conducted in a 5-year-old boy with clinical symptoms and hormonal profile typical of precocious puberty. His parents and 4 sisters were also diagnosed. Single-strand conformation polymorphism analysis under temperature gradient conditions (Multitemperature SSCP) of 3 overlapping fragments of exon 11 of LHR gene revealed a mutation in the fragment spanning nucleotides 1072 to 1804. This mutation was found in the patient, in his mother and in his 4 sisters, and was confirmed by digestion with the use of restriction enzyme Bbr Cl. Direct sequencing revealed a heterozygous T1193C transition in the DNA fragment of the patient and in one of the alleles of his mother's and sister's DNA. This mutation causes Met398Thr substitution in the second transmembrane helix and results in a constitutive activation of LH receptor. This is the second identical mutation detected in Poland and one of the 7 identified so far in the world population.
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Affiliation(s)
- M Ignacak
- Department of Biochemistry and Molecular Biology, University of Medical Sciences, Poznan, Poland.
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Nishi S, Nakabayashi K, Kobilka B, Hsueh AJW. The ectodomain of the luteinizing hormone receptor interacts with exoloop 2 to constrain the transmembrane region: studies using chimeric human and fly receptors. J Biol Chem 2002; 277:3958-64. [PMID: 11723133 DOI: 10.1074/jbc.m109617200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lutropin (LH) and follitropin (FSH) receptors belong to a group of leucine-rich repeat-containing, G protein-coupled receptors (LGRs) found in vertebrates and flies. We fused the ectodomain of human LH or FSH receptors to the transmembrane region of fly LGR2. The chimeric human/fly receptors, unlike their wild type counterparts, exhibited ligand-independent constitutive activity. Because ectodomains likely interact with exoloops to constrain the receptors, individual exoloops of the chimeric receptor containing the ectodomain of the LH receptor and transmembrane region of fly LGR2 was replaced with LH receptor sequences. Chimeric receptors with the ectodomain and exoloop 2, but not exoloop 1 or 3, from LH receptors showed decreases in constitutive activity, but ligand treatment stimulated cAMP production. Furthermore, substitution of key resides in the hinge region of fly LGR2 with LH receptor sequences led to constitutive receptor activation; however, concomitant substitution of the homologous exoloop 2 of the LH receptor decreased G(s) coupling. These results suggest that the hinge region of the LH receptor interacts with exoloop 2 to constrain the receptor in an inactive conformation whereas ligand binding relieves this constraint, leading to G(s) activation.
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Affiliation(s)
- Shinya Nishi
- Division of Reproductive Biology, Department of Gynecology and Obstetrics, Stanford University School of Medicine, Stanford, California 94305, USA
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49
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Govaerts C, Lefort A, Costagliola S, Wodak SJ, Ballesteros JA, Van Sande J, Pardo L, Vassart G. A conserved Asn in transmembrane helix 7 is an on/off switch in the activation of the thyrotropin receptor. J Biol Chem 2001; 276:22991-9. [PMID: 11312274 DOI: 10.1074/jbc.m102244200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The thyrotropin (TSH) receptor is an interesting model to study G protein-coupled receptor activation as many point mutations can significantly increase its basal activity. Here, we identified a molecular interaction between Asp(633) in transmembrane helix 6 (TM6) and Asn(674) in TM7 of the TSHr that is crucial to maintain the inactive state through conformational constraint of the Asn. We show that these residues are perfectly conserved in the glycohormone receptor family, except in one case, where they are exchanged, suggesting a direct interaction. Molecular modeling of the TSHr, based on the high resolution structure of rhodopsin, strongly favors this hypothesis. Our approach combining site-directed mutagenesis with molecular modeling shows that mutations disrupting this interaction, like the D633A mutation in TM6, lead to high constitutive activation. The strongly activating N674D (TM7) mutation, which in our modeling breaks the TM6-TM7 link, is reverted to wild type-like behavior by an additional D633N mutation (TM6), which would restore this link. Moreover, we show that the Asn of TM7 (conserved in most G protein-coupled receptors) is mandatory for ligand-induced cAMP accumulation, suggesting an active role of this residue in activation. In the TSHr, the conformation of this Asn residue of TM7 would be constrained, in the inactive state, by its Asp partner in TM6.
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Affiliation(s)
- C Govaerts
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Nucléaire, Université Libre de Bruxelles, Campus Erasme, 808 route de Lennik, B-1070 Bruxelles, Belgium.
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Abstract
Concepts regarding the mechanisms by which drugs activate receptors to produce physiological response have progressed beyond considering the receptor as a simple on-off switch. Current evidence suggests that the idea that agonists produce only varying degrees of receptor activation is obsolete and must be reconciled with data to show that agonist efficacy has texture as well as magnitude. Thus, agonists can block system constitutive response (inverse agonists), behave as positive and inverse agonists on the same receptor (protean agonists), and differ in the stimulus pattern they produce in physiological systems (ligand-selective agonists). The molecular mechanism for this seemingly diverse array of activities is the same, namely, the selective microaffinity of ligands for different conformational states of the receptor. This paper reviews evidence for the existence of the various types of agonism and the potential therapeutic utility of different agonist types.-Kenakin, T. Inverse, protean, and ligand-selective agonism: matters of receptor conformation.
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Affiliation(s)
- T Kenakin
- Department of Receptor Biochemistry, Glaxo SmithKline Research and Development, Research Triangle Park, North Carolina 27709, USA.
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