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Choi SH, Byambaragchaa M, Kim DJ, Lee JH, Kang MH, Min KS. Specific Signal Transduction of Constitutively Activating (D576G) and Inactivating (R476H) Mutants of Agonist-Stimulated Luteinizing Hormone Receptor in Eel. Int J Mol Sci 2023; 24:ijms24119133. [PMID: 37298083 DOI: 10.3390/ijms24119133] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/02/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2023] Open
Abstract
We investigated the mechanism of signal transduction using inactivating (R476H) and activating (D576G) mutants of luteinizing hormone receptor (LHR) of eel at the conserved regions of intracellular loops II and III, respectively, naturally occurring in mammalian LHR. The expression of D576G and R476H mutants was approximately 58% and 59%, respectively, on the cell surface compared to those of eel LHR-wild type (wt). In eel LHR-wt, cAMP production increased upon agonist stimulation. Cells expressing eel LHR-D576G, a highly conserved aspartic acid residue, exhibited a 5.8-fold increase in basal cAMP response; however, the maximal cAMP response by high-agonist stimulation was approximately 0.62-fold. Mutation of a highly conserved arginine residue in the second intracellular loop of eel LHR (LHR-R476H) completely impaired the cAMP response. The rate of loss in cell-surface expression of eel LHR-wt and D576G mutant was similar to the agonist recombinant (rec)-eel LH after 30 min. However, the mutants presented rates of loss higher than eel LHR-wt did upon rec-eCG treatment. Therefore, the activating mutant constitutively induced cAMP signaling. The inactivating mutation resulted in the loss of LHR expression on the cell surface and no cAMP signaling. These data provide valuable information regarding the structure-function relationship of LHR-LH complexes.
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Affiliation(s)
- Seung-Hee Choi
- Animal BioScience, School of Animal Life Convergence, Hankyong National University, Ansung 17579, Republic of Korea
| | - Munkhzaya Byambaragchaa
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Republic of Korea
| | - Dae-Jung Kim
- Aquaculture Industry Division, South Sea Fisheries Research Institute, National Institute of Fisheries Science (NIFS), Yeosu 59780, Republic of Korea
| | - Jong-Hyuk Lee
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan 31499, Republic of Korea
| | - Kwan-Sik Min
- Animal BioScience, School of Animal Life Convergence, Hankyong National University, Ansung 17579, Republic of Korea
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Republic of Korea
- Carbon-Neutral Resources Research Center, Hankyong National University, Ansung 17579, Republic of Korea
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Activating and inactivating mutations of the human, rat, equine and eel luteinizing hormone/ chorionic gonadotropin receptors (LH/CGRs). JOURNAL OF ANIMAL REPRODUCTION AND BIOTECHNOLOGY 2021. [DOI: 10.12750/jarb.36.4.169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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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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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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Stoy H, Gurevich VV. How genetic errors in GPCRs affect their function: Possible therapeutic strategies. Genes Dis 2015; 2:108-132. [PMID: 26229975 PMCID: PMC4516391 DOI: 10.1016/j.gendis.2015.02.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 02/07/2015] [Indexed: 01/14/2023] Open
Abstract
Activating and inactivating mutations in numerous human G protein-coupled receptors (GPCRs) are associated with a wide range of disease phenotypes. Here we use several class A GPCRs with a particularly large set of identified disease-associated mutations, many of which were biochemically characterized, along with known GPCR structures and current models of GPCR activation, to understand the molecular mechanisms yielding pathological phenotypes. Based on this mechanistic understanding we also propose different therapeutic approaches, both conventional, using small molecule ligands, and novel, involving gene therapy.
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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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Shenker A. Activating Mutations of the Lutropin Choriogonadotropin Receptor in Precocious Puberty. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/10606820212138] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Eunice M, Philibert P, Kulshreshtha B, Audran F, Paris F, Sultan C, Ammini AC. Mother-to-son transmission of a luteinizing hormone receptor activating mutation in a prepubertal child with testotoxicosis. J Pediatr Endocrinol Metab 2009; 22:275-9. [PMID: 19492585 DOI: 10.1515/jpem.2009.22.3.275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AIM To identify the LHR gene mutation in a prepubertal child with testotoxicosis. METHODS Standard RIA procedure was used for estimating LH, FSH and testosterone levels. Molecular analysis was done by standard PCR using different sets of primers and reaction conditions specific for the LHR gene. Direct sequencing was done using the ABI Prism Dye terminator sequencing kit and the ABI 310 sequencing apparatus. RESULTS We found a heterozygous mutation of the LHR gene in exon 11 of the second transmembrane region, Met-->Thr at the 398 position (M398T). The same mutation was also found in the proband's mother. CONCLUSION To our knowledge, this is the first molecular characterization of maternally inherited testotoxicosis in a 5 1/2-year-old boy from the Indian subcontinent.
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Affiliation(s)
- Marumudi Eunice
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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Segaloff DL. Chapter 4 Diseases Associated with Mutations of the Human Lutropin Receptor. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 89:97-114. [DOI: 10.1016/s1877-1173(09)89004-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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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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Arey BJ. Allosteric modulators of glycoprotein hormone receptors: discovery and therapeutic potential. Endocrine 2008; 34:1-10. [PMID: 18956257 DOI: 10.1007/s12020-008-9098-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 06/02/2008] [Accepted: 06/26/2008] [Indexed: 01/27/2023]
Abstract
The glycoprotein hormones, luteinizing hormone, follicle-stimulating hormone and thyroid stimulating hormone, are important regulators of reproductive and metabolic processes. However, because of the nature of their ligand-receptor interactions that contain multiple contact sites, classical small molecule drug discovery strategies have not been successful. However, recent advances in screening and combinatorial chemistry strategies have identified chemical series that act allosterically as positive, negative or mixed modulators of the glycoprotein hormone receptors. This review will discuss the discovery and highlight the currently known series of allosteric modulators to this therapeutically important family of G-protein coupled receptors. Lastly, we will present potential mechanisms whereby the different series could modulate receptor function in the context of currently held theory and known structure of G protein-coupled receptors.
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Affiliation(s)
- Brian J Arey
- Department of Metabolic and Cardiovascular Drug Discovery, Research and Development, Bristol-Myers Squibb Co, 311 Pennington Rocky-Hill Rd, Mail Stop 21-1.08, Pennington, NJ 08534, USA.
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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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Ryan GL, Feng X, d'Alva CB, Zhang M, Van Voorhis BJ, Pinto EM, Kubias AEF, Antonini SR, Latronico AC, Segaloff DL. Evaluating the roles of follicle-stimulating hormone receptor polymorphisms in gonadal hyperstimulation associated with severe juvenile primary hypothyroidism. J Clin Endocrinol Metab 2007; 92:2312-7. [PMID: 17356048 DOI: 10.1210/jc.2006-2086] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Rare activating mutations of the human (h)FSHR have been reported in some women with spontaneous ovarian hyperstimulation in pregnancy, where follicular growth is inappropriately stimulated by elevated concentrations of human chorionic gonadotropin acting through the hFSHR. It is not known whether ovarian hyperstimulation in peripubertal girls with untreated primary hypothyroidism is caused by hFSHR mutations and/or influenced by hFSHR allelic variants, rendering the hFSHR more sensitive to circulating TSH. OBJECTIVE The aim of the study was to determine whether mutations of the hFSHR and/or hFSHR allelic variants are associated with greater sensitivity of the hFSHR to TSH. DESIGN The hFSHR gene was sequenced from eight pediatric patients displaying gonadal hyperstimulation due to primary hypothyroidism. HEK293 cells expressing different hFSHR allelic combinations were studied for their responsiveness to recombinant (r)hTSH. SETTING The study was conducted at university research centers. PATIENTS Eight unrelated patients (seven girls and one boy) who exhibited primary hypothyroidism and gonadal hyperstimulation were included in the study. INTERVENTIONS There were no interventions. MAIN OUTCOME MEASURE DNA sequencing of the hFSHR gene was the main outcome measure. Basal, rhFSHR- and rhTSH receptor-stimulated cAMP levels were assayed in HEK293 cells transfected with the hTSH receptor or different hFSHR allelic combinations. Cell surface receptor numbers were also determined. RESULTS No hFSHR mutations were identified in the patient population, but we did identify two known polymorphisms. In vitro experiments demonstrated a dose-dependent and specific rhTSH-dependent increase in cAMP production in HEK293 cells expressing the wild-type hFSHR, regardless of hFSHR isoform. CONCLUSIONS Pediatric gonadal hyperstimulation associated with severe primary hypothyroidism is likely due to the actions of the elevated concentrations of TSH on the wild-type hFSHR, and this response is not dependent upon the hFSHR isoform.
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Affiliation(s)
- Ginny L Ryan
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, The University of Iowa, Iowa City, IA 52246, USA
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Ascoli M. Potential Leydig cell mitogenic signals generated by the wild-type and constitutively active mutants of the lutropin/choriogonadotropin receptor (LHR). Mol Cell Endocrinol 2007; 260-262:244-8. [PMID: 17055151 PMCID: PMC1761117 DOI: 10.1016/j.mce.2005.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Accepted: 09/23/2005] [Indexed: 11/21/2022]
Affiliation(s)
- Mario Ascoli
- Department of Pharmacology, 2-319B BSB, 51 Newton Road, The University of Iowa, Iowa City, IA 52242-1109, United States.
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Piersma D, Verhoef-Post M, Berns EMJJ, Themmen APN. LH receptor gene mutations and polymorphisms: an overview. Mol Cell Endocrinol 2007; 260-262:282-6. [PMID: 17030087 DOI: 10.1016/j.mce.2005.11.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 11/07/2005] [Indexed: 11/30/2022]
Affiliation(s)
- Djura Piersma
- Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
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Hirakawa T, Ascoli M. A constitutively active somatic mutation of the human lutropin receptor found in Leydig cell tumors activates the same families of G proteins as germ line mutations associated with Leydig cell hyperplasia. Endocrinology 2003; 144:3872-8. [PMID: 12933660 DOI: 10.1210/en.2003-0365] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Using a Leydig tumor cell line (MA-10) transiently transfected with the human lutropin receptor (hLHR) and mutants thereof, we examined the identity of the G proteins activated by the agonist-engaged hLHR-wild type (wt) and by three of its naturally occurring constitutively active mutants. Two of the mutants examined, L457R in transmembrane helix 3 and D578Y in transmembrane helix 6, are germ-line mutations found in boys with Leydig cell hyperplasia and precocious puberty. The third, D578H, is a somatic mutation found in Leydig cell tumors in boys with precocious puberty. We show that the hLHR-wt and the three mutants activate the G(s), G(i/o), and G(q/11), but not the G(12/13), families of G proteins. The activation of these G proteins by the hLHR-wt occurs only when engaged by agonist, but their activation by the L457R, D578Y, and D578H mutants occurs independently of agonist stimulation. We conclude that the G proteins activated by constitutively active mutants of the hLHR associated with Leydig cell hyperplasia or tumors are identical and are the same as those activated by the agonist-engaged hLHR-wt. If there was preferential activation of some G protein families by the somatic D578H mutation found in Leydig cell tumors as opposed to the germ line mutations found in Leydig cell hyperplasia, then one could envision mechanisms by which the D578H mutant would be oncogenic. The data presented here suggest that such mechanisms do not need to be considered.
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MESH Headings
- Animals
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Germ-Line Mutation
- Heterotrimeric GTP-Binding Proteins/metabolism
- Humans
- Hyperplasia
- Leydig Cell Tumor
- Male
- Mice
- Puberty, Precocious/metabolism
- Puberty, Precocious/pathology
- Puberty, Precocious/physiopathology
- Receptors, LH/agonists
- Receptors, LH/genetics
- Receptors, LH/metabolism
- Testicular Neoplasms
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- Takashi Hirakawa
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242, USA
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18
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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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19
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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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20
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Hirakawa T, Galet C, Ascoli M. MA-10 cells transfected with the human lutropin/choriogonadotropin receptor (hLHR): a novel experimental paradigm to study the functional properties of the hLHR. Endocrinology 2002; 143:1026-35. [PMID: 11861529 DOI: 10.1210/endo.143.3.8702] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
MA-10 cells are a clonal strain of mouse Leydig tumor cells that retain many of the properties of Leydig cells including expression of the endogenous lutropin/choriogonadotropin receptor (LHR) and the ability to respond to LH/CG with increased steroidogenesis. Recently we noted a dramatic decrease in expression of the endogenous LHR. Although we do not have an explanation for this decline, we took advantage of it to devise a method that allows for the expression of the recombinant human LHR (hLHR) in a Leydig cell model that is now practically devoid of endogenous LHR. We show that the recombinant hLHR can be expressed at variable densities in MA-10 cells and that it can stimulate cAMP and steroid synthesis as well as activate the inositol phosphate and MAPK cascades. We also show that two naturally occurring mutants of the hLHR associated with Leydig cell hyperplasia and one mutant associated with Leydig cell adenomas are constitutively active when assayed for activation of cAMP, inositol phosphate, progesterone, and MAPK. Our ability to express the hLHR in MA-10 cells (now practically devoid of endogenous LHR) provides a novel paradigm to study the cellular and molecular basis of the functions of the LHR in Leydig cells.
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Affiliation(s)
- Takashi Hirakawa
- Department of Pharmacology, The University of Iowa, Iowa City, Iowa 52242-1109, USA
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21
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Canto P, Söderlund D, Ramón G, Nishimura E, Méndez JP. Mutational analysis of the luteinizing hormone receptor gene in two individuals with Leydig cell tumors. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 108:148-52. [PMID: 11857565 DOI: 10.1002/ajmg.10218] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Inactivating mutations of the luteinizing hormone receptor (LHR) gene in males induce Leydig cell agenesis or hypoplasia, while activating mutations cause testotoxicosis. Recently, it was demonstrated that a somatic heterozygous activating mutation of the LHR gene (Asp578His), limited to the tumor, was the cause of Leydig cell adenomas in three unrelated patients. We describe the molecular study of two unrelated boys with gonadotropin-independent hypersecretion of testosterone due to Leydig cell adenomas. Genomic DNA was extracted from the tumor, the adjacent normal testis tissue, and blood leukocytes. Both individuals exhibited an heterozygous missense mutation, limited only to the tumor, consisting of a guanine (G) to cytosine (C) substitution at codon 578 (GAT to CAT), turning aspartic acid into histidine. The presence of the same mutation in different ethnic groups demonstrates the existence of a mutational hot spot in the LHR gene. Indeed, this mutation occurs at the conserved aspartic acid residue at amino acid 578, where a substitution by glycine is the most common mutation observed in testotoxicosis and where a substitution by tyrosine has been linked to a more severe clinical phenotype where diffuse Leydig cell hyperplasia is found. Our results confirm the fact that somatic activating mutations of gonadotropin receptors are involved in gonadal tumorigenesis.
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Affiliation(s)
- Patricia Canto
- Research Unit in Developmental Biology, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México, D.F., México
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22
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Min L, Galet C, Ascoli M. The association of arrestin-3 with the human lutropin/choriogonadotropin receptor depends mostly on receptor activation rather than on receptor phosphorylation. J Biol Chem 2002; 277:702-10. [PMID: 11696538 DOI: 10.1074/jbc.m106082200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the involvement of the nonvisual arrestins in the agonist-induced internalization of the human lutropin receptor (hLHR) has been documented previously with the use of dominant-negative mutants, a physical association of the nonvisual arrestins with the hLHR in intact cells has not been established. In the studies presented herein, we used a cross-linking/coimmunoprecipitation/immunoblotting approach as well as confocal microscopy to document the association of the hLHR with the nonvisual arrestins in co-transfected 293 cells. We also used this approach to examine the relative importance of receptor activation and receptor phosphorylation in the formation of this complex. Using hLHR mutants that impair phosphorylation, activation, or both, we show that the formation of the hLHR-nonvisual arrestin complex depends mostly on the agonist-induced activation of the hLHR rather than on the phosphorylation of the hLHR. These results stand in contrast to those obtained with several other G protein-coupled receptors (i.e. the beta2-adrenergic receptor, the m2 muscarinic receptor, rhodopsin, and the type 1A angiotensin receptor) where arrestin binding depends mostly on receptor phosphorylation rather than on receptor activation. We have also examined the association of the nonvisual arrestins with naturally occurring gain-of-function mutations of the hLHR found in boys with Leydig cell hyperplasia or Leydig cell adenomas. Our results show that these mutants associate with the nonvisual arrestins in an agonist-independent fashion.
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Affiliation(s)
- Le Min
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242-1109, USA
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23
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Huhtaniemi IT. Mutations of gonadotropins and gonadotropin receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function. Endocr Rev 2000; 21:551-83. [PMID: 11041448 DOI: 10.1210/edrv.21.5.0409] [Citation(s) in RCA: 423] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The recent unraveling of structures of genes for the gonadotropin subunits and gonadotropin receptors has provided reproductive endocrinologists with new tools to study normal and pathological functions of the hypothalamic-pituitary-gonadal axis. Rare inactivating mutations that produce distinctive phenotypes of isolated LH or FSH deficiency have been discovered in gonadotropin subunit genes. In addition, there is a common polymorphism in the LHbeta subunit gene with possible clinical significance as a contributing factor to pathologies of LH-dependent gonadal functions. Both activating and inactivating mutations have been detected in the gonadotropin receptor genes, a larger number in the LH receptor gene, but so far only a few in the gene for the FSH receptor. These mutations corroborate and extend our knowledge of clinical consequences of gonadotropin resistance and inappropriate gonadotropin action. The information obtained from human mutations has been complemented by animal models with disrupted or inappropriately activated gonadotropin ligand or receptor genes. These clinical and experimental genetic disease models form a powerful tool for exploring the physiology and pathophysiology of gonadotropin function and provide an excellent example of the power of molecular biological approaches in the study of pathogenesis of diseases.
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MESH Headings
- Amino Acid Sequence
- Animals
- Female
- Gonadotropins, Pituitary/chemistry
- Gonadotropins, Pituitary/genetics
- Gonadotropins, Pituitary/physiology
- Humans
- Mice
- Mice, Knockout
- Mutation
- Ovary/physiology
- Pituitary Gland/physiology
- Receptors, FSH/chemistry
- Receptors, FSH/genetics
- Receptors, FSH/physiology
- Receptors, Gonadotropin/chemistry
- Receptors, Gonadotropin/genetics
- Receptors, Gonadotropin/physiology
- Receptors, LH/chemistry
- Receptors, LH/genetics
- Receptors, LH/physiology
- Structure-Activity Relationship
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24
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Nordhoff V, Gromoll J, Simoni M. Constitutively active mutations of G protein-coupled receptors: the case of the human luteinizing hormone and follicle-stimulating hormone receptors. Arch Med Res 1999; 30:501-9. [PMID: 10714364 DOI: 10.1016/s0188-4409(99)00076-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Activating mutations of the luteinizing hormone receptor (LHR) and the follicle-stimulating hormone receptor (FSHR) have been known for several years. These activating mutations permanently stimulate, in the absence of their cognate ligand, the receptor signaling pathways. In the case of the LHR, the induced chronic stimulation causes sporadic and familial pseudoprecocious puberty, a phenotype observed only in males. The absence of a female phenotype is probably due to the requirement for FSH in the induction of LHR expression. For the FSHR, one activating mutation was found in a patient with normal spermatogenesis without detectable gonadotropins. Whether activating mutations of the gonadotropin receptors are involved in tumor development is not yet clear. Activating mutations of the FSHR were supposedly involved but not found in ovarian tumors. For the LHR, only one patient with a seminoma and an activating mutation was described. The different occurrence of activating mutations of the LHR compared to the FSHR is surprising, since the two genes are adjacently located on chromosome 2 and should therefore be affected by a similar mutation rate. It might well be that mutations occur with the same frequency, but that activating mutations of the FSHR do not result in any particular phenotype.
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Affiliation(s)
- V Nordhoff
- Institute of Reproductive Medicine of the University, Münster, Germany
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25
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Latronico AC, Segaloff DL. Naturally occurring mutations of the luteinizing-hormone receptor: lessons learned about reproductive physiology and G protein-coupled receptors. Am J Hum Genet 1999; 65:949-58. [PMID: 10486313 PMCID: PMC1288265 DOI: 10.1086/302602] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Ana Claudia Latronico
- Developmental Endocrinology Unit, Hospital das Clinicas, São Paulo University Medical School, São Paulo; and Department of Physiology and Biophysics, The University of Iowa College of Medicine, Iowa City
| | - Deborah L. Segaloff
- Developmental Endocrinology Unit, Hospital das Clinicas, São Paulo University Medical School, São Paulo; and Department of Physiology and Biophysics, The University of Iowa College of Medicine, Iowa City
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26
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Le Gouill C, Parent JL, Caron CA, Gaudreau R, Volkov L, Rola-Pleszczynski M, Stanková J. Selective modulation of wild type receptor functions by mutants of G-protein-coupled receptors. J Biol Chem 1999; 274:12548-54. [PMID: 10212233 DOI: 10.1074/jbc.274.18.12548] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the G-protein-coupled receptor (GPCR) family are involved in most aspects of higher eukaryote biology, and mutations in their coding sequence have been linked to several diseases. In the present study, we report that mutant GPCR can affect the functional properties of the co-expressed wild type (WT) receptor. Mutants of the human platelet-activating factor receptor that fail to show any detectable ligand binding (N285I and K298stop) or coupling to a G-protein (D63N, D289A, and Y293A) were co-expressed with the WT receptor in Chinese hamster ovary and COS-7 cells. In this context, N285I and K298stop mutant receptors inhibited 3H-WEB2086 binding and surface expression. Co-transfection with D63N resulted in a constitutively active receptor phenotype. Platelet-activating factor-induced inositol phosphate production in cells transfected with a 1:1 ratio of WT:D63N was higher than with the WT cDNA alone but was abolished with a 1:3 ratio. We confirmed that these findings could be extended to other GPCRs by showing that co-expression of the WT C-C chemokine receptor 2b with a carboxyl-terminal deletion mutant (K311stop), resulted in a decreased affinity and responsiveness to MCP-1. A better understanding of this phenomenon could lead to important tools for the prevention or treatment of certain diseases.
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Affiliation(s)
- C Le Gouill
- Immunology Division, Department of Pediatrics, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada. sternsdo@
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27
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Kremer H, Martens JW, van Reen M, Verhoef-Post M, Wit JM, Otten BJ, Drop SL, Delemarre-van de Waal HA, Pombo-Arias M, De Luca F, Potau N, Buckler JM, Jansen M, Parks JS, Latif HA, Moll GW, Epping W, Saggese G, Mariman EC, Themmen AP, Brunner HG. A limited repertoire of mutations of the luteinizing hormone (LH) receptor gene in familial and sporadic patients with male LH-independent precocious puberty. J Clin Endocrinol Metab 1999; 84:1136-40. [PMID: 10084607 DOI: 10.1210/jcem.84.3.5515] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Herein, we report mutation analysis of the LH receptor gene in 17 males with LH-independent precocious puberty, of which 8 were familial and 9 had a negative family history. A total of 7 different mutations (all previously reported) were detected in 12 patients. Among 10 European familial male-limited precocious puberty (FMPP) patients who had a LH receptor gene mutation, none had the Asp578Gly mutation, which is responsible for the vast majority of cases in the U.S. The restricted number of activating mutations of the LH receptor observed in this and other studies of FMPP strongly suggests that an activating phenotype is associated with very specific sites in the receptor protein. Clinical follow-up of the 5 patients who did not have LH receptor mutations shows that such cases most likely do not have true FMPP. LH receptor mutation analysis provides a sensitive tool for distinguishing true FMPP from other causes of early-onset LH-independent puberty in males.
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Affiliation(s)
- H Kremer
- Department of Human Genetics, University Hospital, Nijmegen, The Netherlands
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28
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Abell AN, McCormick DJ, Segaloff DL. Certain activating mutations within helix 6 of the human luteinizing hormone receptor may be explained by alterations that allow transmembrane regions to activate Gs. Mol Endocrinol 1998; 12:1857-69. [PMID: 9849960 DOI: 10.1210/mend.12.12.0202] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Male-limited gonadotropin-independent precocious puberty (MPP) is frequently associated with mutations of the human LH/CG receptor (hLHR) that result in constitutively active hLHRs. Many such activating mutations have been identified in transmembrane 6 of the hLHR, with the substitution of Asp-578 being the most frequently observed mutation. Mutagenesis of a transmembrane helix of a G protein-coupled receptor can cause local alterations in the conformation near the mutated residue, allosteric changes elsewhere in the protein, and/or changes in the interhelical packing of the receptor. Therefore, while it has been hypothesized that activation of the receptor by mutations of Asp-578 may arise via alterations in the interactions of helix 6 with other transmembrane helices and/or by allosterically altering the conformation of the third intracellular loop, it has not been possible to ascertain the role of the sixth transmembrane helix per se in activating Gs in the mutated full-length receptor. Recently, however, we have shown that a peptide KMAILIFT, corresponding to the juxtacytoplasmic portion of helix 6 of the hLHR, is capable of activating Gs. These results suggest that helix 6 itself can directly interact with Gs. Importantly, the KMAILIFT peptide did not include Asp-578, which lies just C-terminal to this sequence. We show herein that a peptide extended to include Asp-578 (KMAILIFTDFT) is a poor activator of Gs. However, if the peptide is synthesized with the aspartate replaced with either a glycine or tyrosine, substitutions that are found in some patients with MPP, these peptides have Gs-stimulating activity. Additionally, a transmembrane 6 peptide with the substitution of Ile-575 with leucine, another mutation found in MPP, mimicked the activating effects of this mutation in the full-length receptor. The ability of peptides in which Asp-578 or Ile-575 is substituted to mimic the activating effects of these mutations in the full-length receptor suggests that the sixth transmembrane helix represents a site for direct interaction with Gs. In addition to the stimulatory effects of transmembrane 6 peptides, peptides corresponding to the juxtacytoplasmic portions of the fourth, fifth, and seventh helices were also able to stimulate Gs. These results are consistent with the hypothesis that the transmembrane helices may form a pocket for interaction with Gs and that constitutive activation of the hLHR may involve the opening of the pocket formed by these helices, thus exposing Gs-binding sites on these helices.
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Affiliation(s)
- A N Abell
- Department of Physiology and Biophysics, The University of Iowa College of Medicine, Iowa City 52242, USA
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29
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Abstract
The glycoprotein hormones luteinizing hormone (LH) and human chorionic gonadotropin (hCG), both of which act through the LH receptor, play an important role in the regulation of both male and female gonadal function. Testicular androgen production by the Leydig cells is almost entirely dependent on LH/hCG action, while in the ovary LH triggers both oestrogen and progestin secretion and ovulation of the Graaffian follicles. In this review we discuss the various mutations that have been found in the LH receptor gene in the human and the lessons that can be learned from the phenotypes of the carriers of these mutations.
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Affiliation(s)
- A P Themmen
- Department of Endocrinology and Reproduction, Erasmus University Rotterdam, The Netherlands.
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30
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Tapanainen JS, Vaskivuo T, Aittomäki K, Huhtaniemi IT. Inactivating FSH receptor mutations and gonadal dysfunction. Mol Cell Endocrinol 1998; 145:129-35. [PMID: 9922109 DOI: 10.1016/s0303-7207(98)00179-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A variety of mutations and polymorphisms of genes regulating female and male reproductive functions have been discovered during the last few years. These include several inactivating and activating mutations in LH receptor genes. The first mutation of FSH receptor (FSHR) gene was discovered in six Finnish families. This inactivating Ala189Val transition in the extracellular receptor domain causes primary amenorrhea, arrest of follicular development and infertility in homozygous women. In contrast to females, this mutation did not cause absolute infertility in males but only suppressed spermatogenesis. Another inactivating mutation of the FSHR gene has been found at position 191 (Asn191Ile) in a healthy fertile woman. The studies on inactivating FSHR mutations demonstrate that normal ovarian function is critically dependent on FSH while, in contrast to earlier views, male fertility is less strictly dependent on normal FSH action.
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Affiliation(s)
- J S Tapanainen
- Department of Obstetrics and Gynecology, Oulu University Hospital, Finland.
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31
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Misrahi M, Beau I, Meduri G, Bouvattier C, Atger M, Loosfelt H, Ghinea N, Hai MV, Bougnères PF, Milgrom E. Gonadotropin receptors and the control of gonadal steroidogenesis: physiology and pathology. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1998; 12:35-66. [PMID: 9890061 DOI: 10.1016/s0950-351x(98)80444-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Over the past few years, knowledge of the structure of gonadotropin receptors and their mode of action has rapidly advanced. The cDNA corresponding to the luteinizeng hormone (LH) receptor (LHR) has been cloned, leading to the identification of a novel family of G-protein-coupled receptors. The follicle stimulating hormone (FSH) receptor (FSHR) was thereafter cloned by cross-hybridization with the LHR. Structure-function relationships have been studied by mutagenesis experiments in several laboratories. The cloning and chromosomal localization to chromosome 2p21 of the two human gonadotropin receptor genes has provided insights into their evolutionary relationships. The LHR and FSHR genes are very large and contain 10 and 11 exons respectively. The obtention of monoclonal antibodies against the receptors resulted in the characterization of the receptor proteins. These antibodies also allowed the study of receptor expression in target cells in physiological and pathological conditions. The internalization of the LHR has been studied by electron microscopy. A mechanism of receptor-mediated transcytosis through the endothelial cells of the testes has been described for the LHR. The polarized expression of receptors has been studied. The cloning of gonadotropin receptor genes has opened the field of genetic study of the receptors. Inactivating mutations of the LHR have been described in Leydig cell agenesis or hypoplasia. Different phenotypes, including complete pseudohermaphroditism, ambiguous genitalia and male phenotype, have been described. In the case of the FSHR, only one mutation has been reported in familial ovarian dysgenesis with primary amenorrhea. Related males have variable alterations of spermatogenesis and fertility. Constitutive mutations of the LHR have been reported in familial testotoxicosis. One similar mutation has also been described for the FSHR. Such mutations may lead to the development of a model of receptor activation.
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Affiliation(s)
- M Misrahi
- Unité de Recherches Hormones, Gènes et Reproduction, Institut National de la Santé et de la Recherche Médicale, Le Kremlin Bicêtre, France
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32
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Abstract
Human reproductive function is regulated mainly by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Mutations of the human LH/ chorionic gonadotropin receptor (LHR) and the FSH receptor (FSHR) leading to either constitutive activation or inactivation of the receptors have been identified. All activating mutations of the LHR and the FSHR are located within the exon encoding the transmembrane domain while the inactivating mutations are scattered throughout the coding sequence. A number of activating and inactivating mutations of the LHR have been found while only one activating and three inactivating mutations of the FSHR are known. Activating mutations of the LHR cause familial male-limited precocious puberty (FMPP) while that of the FSHR has been shown to restore the reproductive capability of a hypophysectomized male. Inactivating mutations of the LHR cause Leydig cell hypoplasia (LCH) in males while that of the FSHR causes hereditary hypergonadotropic ovarian dysgenesis (ODG) in females. Activating mutations of both receptors are dominant while inactivating mutations are recessive. Genotype-phenotype correlation is best established for the inactivating mutations of LHR. Severity of clinical phenotype in LCH correlates with the amount of residual activity of the mutated LHR. Comparison of the clinical impact of the activating and the inactivating mutations of the receptors indicates that male reproductive capacity depends primarily on LH while female reproductive capacity depends primarily on FSH.
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Affiliation(s)
- W Y Chan
- Department of Pediatrics, Georgetown University Children's Medical Center, Washington, DC 20007, USA
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33
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Chapter 6 Molecular aspects of precocious puberty. ADVANCES IN MOLECULAR AND CELLULAR ENDOCRINOLOGY 1998. [DOI: 10.1016/s1569-2566(98)80014-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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34
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Abstract
Recent developments in biochemistry, genetics, and clinical research have produced a profound effect on the understanding of normal and abnormal puberty. This article is intended to point out selected new developments that affect the understanding of puberty and clinical practice in disorders of puberty.
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Affiliation(s)
- D M Styne
- Department of Pediatrics, University of California, Davis, School of Medicine, USA
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35
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Bradbury FA, Kawate N, Foster CM, Menon KM. Post-translational processing in the Golgi plays a critical role in the trafficking of the luteinizing hormone/human chorionic gonadotropin receptor to the cell surface. J Biol Chem 1997; 272:5921-6. [PMID: 9038211 DOI: 10.1074/jbc.272.9.5921] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Point mutations in the luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor have been shown to cause constitutive activation which results in precocious puberty in affected males. We introduced one of these mutations, Asp-556 --> Gly, into the rat LH/hCG receptor and demonstrated that the mutant receptor constitutively activated adenylate cyclase in transfected 293 T cells. The cell surface expression of the mutant receptor was lower than that of the wild type receptor. Pulse-chase studies showed that the 73-kDa precursor of both the mutant and wild type receptors was synthesized at comparable efficiencies. However, post-translational processing of the mutant receptor to the mature 92-kDa form, which has N-linked complex type oligosaccharide chains, was impaired. Sensitivity of the mutant receptor to peptide-N-glycanase F and endoglycosidase H, and insensitivity to sialidase indicated that the 73-kDa species represents the high mannose form that has not yet been trafficked through the medial and trans Golgi. Additionally, although the wild type receptor was palmitoylated, the mutant receptor was not. Although the high mannose 73-kDa species is capable of binding LH/hCG, our results show that post-translational processing in the Golgi is required for the mature 92-kDa receptor to reach the cell surface.
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Affiliation(s)
- F A Bradbury
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0617, USA
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