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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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Jonas KC, Rivero Müller A, Oduwole O, Peltoketo H, Huhtaniemi I. The Luteinizing Hormone Receptor Knockout Mouse as a Tool to Probe the In Vivo Actions of Gonadotropic Hormones/Receptors in Females. Endocrinology 2021; 162:6144965. [PMID: 33605422 PMCID: PMC8171189 DOI: 10.1210/endocr/bqab035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Indexed: 11/25/2022]
Abstract
Mouse models with altered gonadotropin functions have provided invaluable insight into the functions of these hormones/receptors. Here we describe the repurposing of the infertile and hypogonadal luteinizing hormone receptor (LHR) knockout mouse model (LuRKO), to address outstanding questions in reproductive physiology. Using crossbreeding strategies and physiological and histological analyses, we first addressed the physiological relevance of forced LHR homomerization in female mice using BAC expression of 2 ligand-binding and signaling deficient mutant LHR, respectively, that have previously shown to undergo functional complementation and rescue the hypogonadal phenotype of male LuRKO mice. In female LuRKO mice, coexpression of signaling and binding deficient LHR mutants failed to rescue the hypogonadal and anovulatory phenotype. This was apparently due to the low-level expression of the 2 mutant LHR and potential lack of luteinizing hormone (LH)/LHR-dependent pleiotropic signaling that has previously been shown at high receptor densities to be essential for ovulation. Next, we utilized a mouse model overexpressing human chorionic gonadotropin (hCG) with increased circulating "LH/hCG"-like bioactivity to ~40 fold higher than WT females, to determine if high circulating hCG in the LuRKO background could reveal putative LHR-independent actions. No effects were found, thus, suggesting that LH/hCG mediate their gonadal and non-gonadal effects solely via LHR. Finally, targeted expression of a constitutively active follicle stimulating hormone receptor (FSHR) progressed antral follicles to preovulatory follicles and displayed phenotypic markers of enhanced estrogenic activity but failed to induce ovulation in LuRKO mice. This study highlights the critical importance and precise control of functional LHR and FSHR for mediating ovarian functions and of the potential repurposing of existing genetically modified mouse models in answering outstanding questions in reproductive physiology.
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Affiliation(s)
- Kim Carol Jonas
- Department of Women and Children’s Health, King’s College London,
London SE1 1UL, UK
- Institute of Reproductive and Developmental Biology, Department of Metabolism,
Digestion and Reproduction, Imperial College London, London W12
0NN, UK
- Correspondence: Dr Kim Jonas, Department of Women and Children’s Health, King’s College London,
London SE1 1UL, UK; Institute of Reproductive and Developmental Biology, Department of
Metabolism, Digestion and Reproduction, Imperial College London, London W12 0NN, UK.
; or Prof. Ilpo Huhtaniemi, Institute of Reproductive and
Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial
College London, London, W12 0NN, UK; Institute for Biomedicine, Department of Physiology,
University of Turku, 20520 Turku, Finland.
| | - Adolfo Rivero Müller
- Institute for Biomedicine, Department of Physiology, University of
Turku, 20520 Turku, Finland
- Department of Biochemistry and Molecular Biology, Medical University of
Lublin, 20-093 Lublin, Poland
| | - Olayiwola Oduwole
- Institute of Reproductive and Developmental Biology, Department of Metabolism,
Digestion and Reproduction, Imperial College London, London W12
0NN, UK
| | - Hellevi Peltoketo
- Institute of Reproductive and Developmental Biology, Department of Metabolism,
Digestion and Reproduction, Imperial College London, London W12
0NN, UK
- Laboratory of Cancer Genetics and Tumour Biology, Cancer and Translational
Medicine Research Unit, Biocenter Oulu and University of Oulu,
90220 Oulu, Finland
| | - Ilpo Huhtaniemi
- Institute of Reproductive and Developmental Biology, Department of Metabolism,
Digestion and Reproduction, Imperial College London, London W12
0NN, UK
- Institute for Biomedicine, Department of Physiology, University of
Turku, 20520 Turku, Finland
- Correspondence: Dr Kim Jonas, Department of Women and Children’s Health, King’s College London,
London SE1 1UL, UK; Institute of Reproductive and Developmental Biology, Department of
Metabolism, Digestion and Reproduction, Imperial College London, London W12 0NN, UK.
; or Prof. Ilpo Huhtaniemi, Institute of Reproductive and
Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial
College London, London, W12 0NN, UK; Institute for Biomedicine, Department of Physiology,
University of Turku, 20520 Turku, Finland.
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Montenegro LR, Lerário AM, Nishi MY, Jorge AA, Mendonca BB. Performance of mutation pathogenicity prediction tools on missense variants associated with 46,XY differences of sex development. Clinics (Sao Paulo) 2021; 76:e2052. [PMID: 33503178 PMCID: PMC7811835 DOI: 10.6061/clinics/2021/e2052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/27/2020] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES Single nucleotide variants (SNVs) are the most common type of genetic variation among humans. High-throughput sequencing methods have recently characterized millions of SNVs in several thousand individuals from various populations, most of which are benign polymorphisms. Identifying rare disease-causing SNVs remains challenging, and often requires functional in vitro studies. Prioritizing the most likely pathogenic SNVs is of utmost importance, and several computational methods have been developed for this purpose. However, these methods are based on different assumptions, and often produce discordant results. The aim of the present study was to evaluate the performance of 11 widely used pathogenicity prediction tools, which are freely available for identifying known pathogenic SNVs: Fathmn, Mutation Assessor, Protein Analysis Through Evolutionary Relationships (Phanter), Sorting Intolerant From Tolerant (SIFT), Mutation Taster, Polymorphism Phenotyping v2 (Polyphen-2), Align Grantham Variation Grantham Deviation (Align-GVGD), CAAD, Provean, SNPs&GO, and MutPred. METHODS We analyzed 40 functionally proven pathogenic SNVs in four different genes associated with differences in sex development (DSD): 17β-hydroxysteroid dehydrogenase 3 (HSD17B3), steroidogenic factor 1 (NR5A1), androgen receptor (AR), and luteinizing hormone/chorionic gonadotropin receptor (LHCGR). To evaluate the false discovery rate of each tool, we analyzed 36 frequent (MAF>0.01) benign SNVs found in the same four DSD genes. The quality of the predictions was analyzed using six parameters: accuracy, precision, negative predictive value (NPV), sensitivity, specificity, and Matthews correlation coefficient (MCC). Overall performance was assessed using a receiver operating characteristic (ROC) curve. RESULTS Our study found that none of the tools were 100% precise in identifying pathogenic SNVs. The highest specificity, precision, and accuracy were observed for Mutation Assessor, MutPred, SNP, and GO. They also presented the best statistical results based on the ROC curve statistical analysis. Of the 11 tools evaluated, 6 (Mutation Assessor, Phanter, SIFT, Mutation Taster, Polyphen-2, and CAAD) exhibited sensitivity >0.90, but they exhibited lower specificity (0.42-0.67). Performance, based on MCC, ranged from poor (Fathmn=0.04) to reasonably good (MutPred=0.66). CONCLUSION Computational algorithms are important tools for SNV analysis, but their correlation with functional studies not consistent. In the present analysis, the best performing tools (based on accuracy, precision, and specificity) were Mutation Assessor, MutPred, and SNPs&GO, which presented the best concordance with functional studies.
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Affiliation(s)
- Luciana R. Montenegro
- Unidade de Endocrinologia do Desenvolvimento / LIM42 / SELA, Disciplina de Endocrinologia, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
- *Corresponding Authors. E-mail:
| | - Antônio M. Lerário
- Unidade de Endocrinologia do Desenvolvimento / LIM42 / SELA, Disciplina de Endocrinologia, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
- Division of Metabolism, Department of Internal Medicine, Endocrinology and Diabetes, University of Michigan, Ann Arbor, United States of America
| | - Miriam Y. Nishi
- Unidade de Endocrinologia do Desenvolvimento / LIM42 / SELA, Disciplina de Endocrinologia, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Alexander A.L. Jorge
- Unidade de Endocrinologia Genetica (LIM25), Disciplina de Endocrinologia, Faculdade de Medicina (FMUSP), Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Berenice B. Mendonca
- Unidade de Endocrinologia do Desenvolvimento / LIM42 / SELA, Disciplina de Endocrinologia, Hospital das Clinicas (HCFMUSP), Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, BR
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Daussac A, Barat P, Servant N, Yacoub M, Missonier S, Lavran F, Gaspari L, Sultan C, Paris F. Testotoxicosis without Testicular Mass: Revealed by Peripheral Precocious Puberty and Confirmed by Somatic LHCGR Gene Mutation. Endocr Res 2020; 45:32-40. [PMID: 31394950 DOI: 10.1080/07435800.2019.1645163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Purpose: Testotoxicosis is an autosomal dominant form of limited gonadotropin-independent precocious puberty in boys. It is caused by a heterozygous constitutively activating mutation of the LHCGR gene encoding the luteinizing/hormone receptor (LHR). Some twenty mutations of the LHCGR gene have been reported. Most of them are constitutive mutations isolated from blood leukocyte DNA, although others are somatic, found only in testicular tumoural tissue. In all the previously reported cases of these somatic mutations, the tumour, whether a nodular Leydig cell adenoma or hyperplasia, was easily visible on testicular ultrasonography. The aim of this study was to describe an unusual presentation of a patient with the clinical and hormonal characteristics of testotoxicosis but no well-circumscribed lesion at testicular ultrasonography.Materials and Methods: Molecular analysis of the LHCGR gene was performed by direct sequencing of DNA extracted from peripheral leucocytes and testicular biopsy.Results: Molecular analysis didn't find any LHR mutation in blood, whereas it revealed for the first time a somatic D578H mutation in testicular tissue despite no evidence of a nodular aspect at testis ultrasonography.Conclusions: This observation underlines the need to look for a somatic LHCGR gene mutation from the testicular biopsies of all boys with testotoxicosis with no constitutive LHCGR gene mutation identified from blood DNA, even in the absence of circumscribed testicular lesion at ultrasonography. In addition, based on the known link between LHR mutations and testicular tumourigenesis, yearly ultrasound monitoring of the testes should be considered for these patients.
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Affiliation(s)
- A Daussac
- Département de Pédiatrie, Endocrinologie Pédiatrique, CHU de Bordeaux, Bordeaux, France
| | - P Barat
- Département de Pédiatrie, Endocrinologie Pédiatrique, CHU de Bordeaux, Bordeaux, France
- Département de Pédiatrie, Centre d'Investigation Clinique (CIC 0005), CHU de Bordeaux, Bordeaux, France
| | - N Servant
- Département d'Hormonologie (Développement et Reproduction), CHU de Montpellier, Hôpital Lapeyronie, Université de Montpellier, Montpellier, France
| | - M Yacoub
- Unité d'Anatomo cytopathologie, CHU de Bordeaux, Bordeaux, France
| | - S Missonier
- Unité de Radiologie pédiatrique, CHU de Bordeaux, Bordeaux, France
| | - F Lavran
- Unité de Chirurgie viscérale pédiatrique, CHU de Bordeaux, Bordeaux, France
| | - L Gaspari
- Unité d'Endocrinologie-Gynécologie Pédiatriques, Département de Pédiatrie, CHU de Montpellier, Hôpital Arnaud de Villeneuve, Université Montpellier 1, Montpellier, France
| | - C Sultan
- Département d'Hormonologie (Développement et Reproduction), CHU de Montpellier, Hôpital Lapeyronie, Université de Montpellier, Montpellier, France
- Unité d'Endocrinologie-Gynécologie Pédiatriques, Département de Pédiatrie, CHU de Montpellier, Hôpital Arnaud de Villeneuve, Université Montpellier 1, Montpellier, France
| | - F Paris
- Département d'Hormonologie (Développement et Reproduction), CHU de Montpellier, Hôpital Lapeyronie, Université de Montpellier, Montpellier, France
- Unité d'Endocrinologie-Gynécologie Pédiatriques, Département de Pédiatrie, CHU de Montpellier, Hôpital Arnaud de Villeneuve, Université Montpellier 1, Montpellier, France
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Núñez Miguel R, Sanders J, Furmaniak J, Smith BR. Structure and activation of the TSH receptor transmembrane domain. AUTOIMMUNITY HIGHLIGHTS 2016; 8:2. [PMID: 27921237 PMCID: PMC5136658 DOI: 10.1007/s13317-016-0090-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/23/2016] [Indexed: 12/30/2022]
Abstract
PURPOSE The thyroid-stimulating hormone receptor (TSHR) is the target autoantigen for TSHR-stimulating autoantibodies in Graves' disease. The TSHR is composed of: a leucine-rich repeat domain (LRD), a hinge region or cleavage domain (CD) and a transmembrane domain (TMD). The binding arrangements between the TSHR LRD and the thyroid-stimulating autoantibody M22 or TSH have become available from the crystal structure of the TSHR LRD-M22 complex and a comparative model of the TSHR LRD in complex with TSH, respectively. However, the mechanism by which the TMD of the TSHR and the other glycoprotein hormone receptors (GPHRs) becomes activated is unknown. METHODS We have generated comparative models of the structures of the inactive (TMD_In) and active (TMD_Ac) conformations of the TSHR, follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) TMDs. The structures of TMD_Ac and TMD_In were obtained using class A GPCR crystal structures for which fully active and inactive conformations were available. RESULTS Most conserved motifs observed in GPCR TMDs are also observed in the amino acid sequences of GPHR TMDs. Furthermore, most GPCR TMD conserved helix distortions are observed in our models of the structures of GPHR TMDs. Analysis of these structures has allowed us to propose a mechanism for activation of GPHR TMDs. CONCLUSIONS Insight into the mechanism of activation of the TSHR by both TSH and TSHR autoantibodies is likely to be useful in the development of new treatments for Graves' disease.
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Affiliation(s)
| | - Jane Sanders
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, CF14 5DU, UK
| | - Jadwiga Furmaniak
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, CF14 5DU, UK
| | - Bernard Rees Smith
- FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, CF14 5DU, UK.
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Charmandari E, Guan R, Zhang M, Silveira LG, Fan QR, Chrousos GP, Sertedaki AC, Latronico AC, Segaloff DL. Misfolding Ectodomain Mutations of the Lutropin Receptor Increase Efficacy of Hormone Stimulation. Mol Endocrinol 2015; 30:62-76. [PMID: 26554443 DOI: 10.1210/me.2015-1205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We demonstrate 2 novel mutations of the LHCGR, each homozygous, in a 46,XY patient with severe Leydig cell hypoplasia. One is a mutation in the signal peptide (p.Gln18_Leu19ins9; referred to here as SP) that results in an alteration of the coding sequence of the N terminus of the mature mutant receptor. The other mutation (p.G71R) is also within the ectodomain. Similar to many other inactivating mutations, the cell surface expression of recombinant human LHR(SP,G71R) is greatly reduced due to intracellular retention. However, we made the unusual discovery that the intrinsic efficacy for agonist-stimulated cAMP in the reduced numbers of receptors on the cell surface was greatly increased relative to the same low number of cell surface wild-type receptor. Remarkably, this appears to be a general attribute of misfolding mutations in the ectodomains, but not serpentine domains, of the gonadotropin receptors. These findings suggest that there must be a common, shared mechanism by which disparate mutations in the ectodomain that cause misfolding and therefore reduced cell surface expression concomitantly confer increased agonist efficacy to those receptor mutants on the cell surface. Our data further suggest that, due to their increased agonist efficacy, extremely small changes in cell surface expression of misfolded ectodomain mutants cause larger than expected alterations in the cellular response to agonist. Therefore, for inactivating LHCGR mutations causing ectodomain misfolding, the numbers of cell surface mutant receptors on fetal Leydig cells of 46,XY individuals exert a more exquisite effect on the relative severity of the clinical phenotypes than already appreciated.
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Affiliation(s)
- E Charmandari
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - R Guan
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - M Zhang
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - L G Silveira
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Q R Fan
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - G P Chrousos
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - A C Sertedaki
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - A C Latronico
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - D L Segaloff
- Division of Endocrinology, Metabolism and Diabetes (E.C., G.P.C., A.C.S.), First Department of Pediatrics, University of Athens Medical School, Aghia Sophia Children's Hospital, and Division of Endocrinology and Metabolism (E.C., G.P.C., A.C.S.), Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece; Department of Pharmacology (Q.R.F.), Columbia University Medical Center, New York, New York 10032; Unidade de Endocrinologia do Desenvolvimento (L.G.S., A.C.L.), Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and Department of Molecular Physiology and Biophysics (M.Z., R.G., D.L.S.), The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
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7
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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: 34] [Impact Index Per Article: 3.8] [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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8
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Characterization of G protein coupling mediated by the conserved D134(3.49) of DRY motif, M241(6.34), and F251(6.44) residues on human CXCR1. FEBS Open Bio 2015; 5:182-90. [PMID: 25834784 PMCID: PMC4372616 DOI: 10.1016/j.fob.2015.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/27/2015] [Accepted: 03/03/2015] [Indexed: 01/01/2023] Open
Abstract
Mutations in the DRY motif of CXCR1 abolish ligand binding and receptor activation. Point mutations between TM6 and i3 loop result in constitutive activity of CXCR1. Constitutive activity of mutant CXCR1 occurs via Gα15 signaling activation. The highly conserved DRY motifs have distinct roles in CXCR1 and CXCR2.
CXCR1, a receptor for interleukin-8 (IL-8), plays an important role in defending against pathogen invasion during neutrophil-mediated innate immune response. Human CXCR1 is a G protein-coupled receptor (GPCR) with its characteristic seven transmembrane domains (TMs). Functional and structural analyses of several GPCRs have revealed that conserved residues on TM3 (including the highly conserved Asp-Arg-Tyr (DRY) motif) and TM6 near intracellular loops contain domains critical for G protein coupling as well as GPCR activation. The objective of this study was to elucidate the role of critical amino acid residues on TM3 near intracellular loop 2 (i2) and TM6 near intracellular loop 3 (i3), including S1323.47 (Baldwin location), D1343.49, M2416.34, and F2516.44, in G protein coupling and CXCR1 activation. The results demonstrate that mutations of D1343.49 at DRY motif of CXCR1 (D134N and D134V) completely abolished the ligand binding and functional response of the receptor. Additionally, point mutations at positions 241 and 251 between TM6 and i3 loop generated mutant receptors with modest constitutive activity via Gα15 signaling activation. Our results show that D1343.49 on the highly conserved DRY motif has a distinct role for CXCR1 compared to its homologues (CXCR2 and KSHV-GPCR) in G protein coupling and receptor activation. In addition, M2416.34 and F2516.44 along with our previously identified V2476.40 on TM6 are spatially located in a “hot spot” likely essential for CXCR1 activation. Identification of these amino acid residues may be useful for elucidating mechanism of CXCR1 activation and designing specific antagonists for the treatment of CXCR1-mediated diseases.
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Key Words
- CXCR1
- CXCR1, CXC receptor 1
- Chemokine receptor
- Constitutive activity
- DRY motif, Asp-Arg-Tyr motif
- G protein coupled receptor
- GPCR, G protein-coupled receptor
- Gα15
- Gαi
- IL-8, interleukin 8
- IP, inositol phosphate
- Kd, affinity constants
- PLC, phospholipase C
- PTX, pertussis toxin
- TMs, transmembrane domain
- WT, wild type
- i2, intracellular loop 2
- i3, intracellular loop 3
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Zhang M, Guan R, Segaloff DL. Revisiting and questioning functional rescue between dimerized LH receptor mutants. Mol Endocrinol 2012; 26:655-68. [PMID: 22403174 DOI: 10.1210/me.2011-1285] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The glycoprotein hormone receptors are G protein-coupled receptors containing a large extracellular domain fused to a prototypical serpentine domain. cis-activation occurs when binding of hormone to the extracellular domain stabilizes the serpentine domain in an active conformation. Studies by others suggested that these receptors can also signal by trans-activation, where hormone binding to one receptor protomer activates the serpentine domain of an associated protomer, as documented by the partial rescue of hormone-dependent signaling when a binding defective mutant is coexpressed with a signaling defective mutant. However, our characterizations of several LH receptor (LHR) mutants used in previous studies differ markedly from those originally reported. Also, when examining a pair of LHR mutants previously shown to functionally rescue in vitro as well as in vivo, in addition to finding that the properties of the individual mutants differ significantly from those originally described, we determined that when this pair of mutants was coexpressed in vitro, quantitative analyses did not indicate functional rescue. Additional data are presented that provide a plausible alternate explanation for the apparent in vivo trans-activation that was reported. Finally, using LHR mutants that we have documented to be expressed at the cell surface but to lack human chorionic gonadotropin binding activity or to be severely impaired in their ability to activate Gs, we did not observe functional rescue of human chorionic gonadotropin-stimulated cAMP when the mutants were coexpressed, even though bioluminescence resonance energy transfer analyses confirmed that the coexpressed mutants formed dimers. Taken altogether, our data substantively question the concept of functional rescue between LHR mutants.
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Affiliation(s)
- Meilin Zhang
- Department of Molecular Physiology and Biophysics, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52246, USA
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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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11
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Dastmalchi S, Church WB, Morris MB. Modelling the structures of G protein-coupled receptors aided by three-dimensional validation. BMC Bioinformatics 2008; 9 Suppl 1:S14. [PMID: 18315845 PMCID: PMC2259415 DOI: 10.1186/1471-2105-9-s1-s14] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Background G protein-coupled receptors (GPCRs) are abundant, activate complex signalling and represent the targets for up to ~60% of pharmaceuticals but there is a paucity of structural data. Bovine rhodopsin is the first GPCR for which high-resolution structures have been completed but significant variations in structure are likely to exist among the GPCRs. Because of this, considerable effort has been expended on developing in silico tools for refining structures of individual GPCRs. We have developed REPIMPS, a modification of the inverse-folding software Profiles-3D, to assess and predict the rotational orientation and vertical position of helices within the helix bundle of individual GPCRs. We highlight the value of the method by applying it to the Baldwin GPCR template but the method can, in principle, be applied to any low- or high-resolution membrane protein template or structure. Results 3D models were built for transmembrane helical segments of 493 GPCRs based on the Baldwin template, and the models were then scored using REPIMPS and Profiles-3D. The compatibility scores increased significantly using REPIMPS because it takes into account the physicochemical properties of the (lipid) environment surrounding the helix bundle. The arrangement of helices in the helix bundle of the 493 models was then altered systematically by rotating the individual helices. For most GPCRs in the set, changes in the rotational position of one or more helices resulted in significant improvement in the compatibility scores. In particular, for most GPCRs, a rotation of helix VII by 240–300° resulted in improved scores. Bovine rhodopsin modelled using this method showed 3.31 Å RMSD to its crystal structure for 198 Cα atom pairs, suggesting the utility of the method even when starting with idealised structures such as the Baldwin template. Conclusion We have developed an in silico tool which can be used to test the validity of, and refine, models of GPCRs with respect to helix rotation and vertical position based on the physicochemical properties of amino acids and the surrounding environment. The method can be applied to any multi-pass membrane protein and potentially can be used in combination with other high-throughput methodologies to generate and refine models of membrane proteins.
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Affiliation(s)
- Siavoush Dastmalchi
- School of Pharmacy, Tabriz University of Medical Sciences, Tabriz 51664, Iran.
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Latronico AC, Segaloff DL. Insights learned from L457(3.43)R, an activating mutant of the human lutropin receptor. Mol Cell Endocrinol 2007; 260-262:287-93. [PMID: 17055147 PMCID: PMC1785107 DOI: 10.1016/j.mce.2005.11.053] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Accepted: 11/21/2005] [Indexed: 11/15/2022]
Abstract
The L457(3.43)R mutation of the hLHR was initially identified in a Brazilian boy with gonadotropin-independent precocious puberty. As would be expected, L457(3.43)R, when expressed in 293 cells, caused a marked elevation in basal cAMP levels. Interestingly, in spite of the fact that the elevated basal levels of cAMP elicited by L457R were not as great as those elicited by the wild-type hLHR when stimulated with hCG, L457(3.43)R cells were unresponsive to further hormonal stimulation. We have since determined that the L457(3.43)R mutant, as well as other constitutively active mutants of the hLHR, causes an increase in phosphodiesterase activity that attenuates the target cell to hormonal stimulation of the wild-type hLHR or other Gs-coupled GPCRs. We have also shown that the constitutive activity and lack of hormonal responsiveness of L457(3.43)R are due to the formation of a salt bridge between the introduced arginine in the mid portion of helix 3 with D578(6.44) in the mid portion of helix 6. The formation of this salt bridge results in the disruption of interactions between the cytoplasmic ends of helices 3 and 6 that are associated in general with activation of the hLHR. As such, this mutant has provided novel insights into the properties of target cells expressing activating hLHR mutants and into the structural basis for hLHR activation.
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Affiliation(s)
- Ana Claudia Latronico
- Developmental Endocrinology Unit, Hormone and Molecular Genetics Laboratory, Clinical Hospital, Sao Paulo University Medical School, Sao Paulo, Brazil
| | - Deborah L. Segaloff
- Department of Physiology and Biophysics, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA, 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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D’Antona AM, Ahn KH, Wang L, Mierke DF, Lucas-Lenard J, Kendall DA. A cannabinoid receptor 1 mutation proximal to the DRY motif results in constitutive activity and reveals intramolecular interactions involved in receptor activation. Brain Res 2006; 1108:1-11. [PMID: 16879811 PMCID: PMC2733829 DOI: 10.1016/j.brainres.2006.05.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Revised: 05/04/2006] [Accepted: 05/06/2006] [Indexed: 11/25/2022]
Abstract
Activation of a G-protein-coupled receptor involves changes in specific microdomain interactions within the transmembrane region of the receptor. Here, we have focused on the role of L207, proximal to the DRY motif of the human cannabinoid receptor 1 in the interconversion of the receptor resting and active states. Ligand binding analysis of the mutant receptor L207A revealed an enhanced affinity for agonists (three- to six-fold) and a diminished affinity for inverse agonists (19- to 35-fold) compared to the wild-type receptor, properties characteristic of constitutive activity. To further examine whether this mutant adopts a ligand-independent, active form, treatment with GTPgammaS was used to inhibit G protein coupling. Under these conditions, the L207A receptor exhibited a 10-fold increase in affinity for the inverse agonist SR141716A, consistent with a shift away from an enhanced precoupled state. Analysis of the cellular activity of the L207A receptor showed elevated basal cyclic AMP accumulation relative to the wild type that is inhibited by SR141716A, consistent with receptor-mediated Gs precoupling. Using toxins to selectively abrogate Gs or Gi coupling, we found that CP55940 nonetheless induced only a Gi response suggesting a strong preference of this ligand-bound form for Gi in this system. Molecular dynamics simulations reveal that the single residue change of L207A impacts the association of TM3 and TM6 in the receptor by altering hydrophobic interactions involving L207, the salt bridge involving the Arg of the DRY motif, and the helical structure of TM6, consistent with events leading to activation. The structural alterations parallel those observed in models of a mutant CB(1) receptor T210I, with established constitutive activity (D'Antona, A.M., Ahn, K.H. and Kendall, D.A., 2006. Mutations of CB1 T210 produce active and inactive receptor forms: correlations with ligand affinity, receptor stability, and cellular localization. Biochemistry, 45, 5606-5617).
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Affiliation(s)
- Aaron M. D’Antona
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Kwang H. Ahn
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Lei Wang
- Department of Chemistry and Department of Molecular Pharmacology, Brown University, Providence, RI 02912, USA
| | - Dale F. Mierke
- Department of Chemistry and Department of Molecular Pharmacology, Brown University, Providence, RI 02912, USA
| | - Jean Lucas-Lenard
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Debra A. Kendall
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
- Corresponding author. E-mail address: (D.A. Kendall)
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Galet C, Ascoli M. A constitutively active mutant of the human lutropin receptor (hLHR-L457R) escapes lysosomal targeting and degradation. Mol Endocrinol 2006; 20:2931-45. [PMID: 16803865 PMCID: PMC1626098 DOI: 10.1210/me.2006-0138] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Using biochemical and imaging approaches, we examined the postendocytotic fate of the complex formed by human choriogonadotropin (hCG) and a constitutively active mutant of the human lutropin receptor (hLHR-L457R) found in a boy with precocious puberty and Leydig cell hyperplasia. After internalization, some of the complex formed by the hLHR-wild type (hLHR-wt) and hCG recycles to the cell surface, and some is found in lysosomes where the hormone is degraded. In contrast, the complex formed by the hLHR-L457R and hCG is not routed to the lysosomes, most of it is recycled to the cell surface and hormone degradation is barely detectable. For both, hLHR-wt and -L457R, there is an hCG-induced loss of cell surface receptors that accompanies internalization but this loss cannot be prevented by leupeptin. The removal of recycling motifs of the hLHR by truncation of the C-terminal tail at residue 682 greatly enhances the lysosomal accumulation of the hormone-receptor complexes formed by the hLHR-wt or the L457R mutant, the degradation of the internalized hormone, and the loss of cell surface receptors. The degradation of the hormone internalized by these mutants as well as the loss of cell surface receptors is largely prevented by leupeptin. These results highlight a previously unrecognized complexity in the postendocytotic trafficking of the hLHR and document a clear difference between the properties of the constitutively active mutant and the agonist-activated hLHR-wt. This lack of lysosomal degradation of the L457R mutant could contribute to its constitutive activity by prolonging the duration of signaling.
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Affiliation(s)
- Colette Galet
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, 2-319B Bowen Science Building, 51 Newton Road, Iowa City, Iowa 52242-1109, USA
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Zhang M, Mizrachi D, Fanelli F, Segaloff DL. The formation of a salt bridge between helices 3 and 6 is responsible for the constitutive activity and lack of hormone responsiveness of the naturally occurring L457R mutation of the human lutropin receptor. J Biol Chem 2005; 280:26169-76. [PMID: 15908694 PMCID: PMC1237128 DOI: 10.1074/jbc.m502102200] [Citation(s) in RCA: 45] [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
The human lutropin receptor (hLHR) plays a pivotal role in reproductive endocrinology. A number of naturally occurring mutations of the hLHR have been identified that cause the receptor to become constitutively active. To gain further insights into the structural basis for the activation of the hLHR by activating mutations, we chose to examine a particularly strong constitutively activating mutation of this receptor, L457R, in which a leucine that is highly conserved among rhodopsin-like G protein-coupled receptors in helix 3 has been substituted with arginine. Using both disruptive as well as reciprocal mutagenesis strategies, our studies demonstrate that the ability of L457R to stabilize an active form of the hLHR is because of the formation of a salt bridge between the replacing amino acid and Asp-578 in helix 6. Such a lock between the transmembrane portions of helices 3 and 6 is concurrent with weakening the connections between the cytosolic ends of the same helices, including the interaction found in the wild-type receptor between Arg-464, of the (E/D)R(Y/W) motif, and Asp-564. This structural effect is properly marked by the increase in the solvent accessibility of selected amino acids at the cytosolic interfaces between helices 3 and 6. The integrity of the conserved amino acids Asn-615 and Asn-619 in helix 7 is required for the transfer of the structural change from the activating mutation site to the cytosolic interface between helices 3 and 6. The results of in vitro and computational experiments further suggest that the structural trigger of the constitutive activity of the L457R mutant may also be responsible for its lack of hormone responsiveness.
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Affiliation(s)
- Meilin Zhang
- From the Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242 and
| | - Dario Mizrachi
- From the Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242 and
| | - Francesca Fanelli
- the Dulbecco Telethon Institute and Department of Chemistry, University of Modena e Reggio Emilia, Via Campi 183, 41100 Modena, Italy
| | - Deborah L. Segaloff
- From the Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242 and
- ** To whom correspondence should be addressed: Dept. of Physiology and Biophysics, 5–470 Bowen Science Bldg., The University of Iowa, IA City, IA 52242. Tel.: 319-335-7850; Fax: 319-335-7330; E-mail:
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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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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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