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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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2
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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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Cunha-Silva M, Brito VN, Macedo DB, Bessa DS, Ramos CO, Lima LG, Barroso PS, Arnhold IJP, Segaloff DL, Mendonca BB, Latronico AC. Spontaneous fertility in a male patient with testotoxicosis despite suppression of FSH levels. Hum Reprod 2019. [PMID: 29538680 DOI: 10.1093/humrep/dey049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Testotoxicosis is a rare cause of peripheral precocious puberty in boys caused by constitutively activating mutations of the LHCG receptor. Affected males usually have normal gonadotropin profiles and fertility in their adult life. Here, we described the long-term follow-up of a 24-year-old young man with severe testotoxicosis due to a de novo activating mutation in the third transmembrane helix of the LHCGR (p.Leu457Arg). This patient was treated with different medications, including medroxyprogesterone acetate, ketoconazole, cyproterone acetate and aromatase inhibitor from age 2.5 to 9.5 years. His basal and GnRH-stimulated gonadotropin levels were continually suppressed during and after medical treatment. At adulthood, extremely high serum testosterone levels (>35 nmol/L), undetectable gonadotropin levels (LH < 0.15 IU/L and FSH < 0.6 IU/L) and oligozoospermia were evidenced. Despite his suppressed FSH levels and an unfavorable spermogram, the patient fathered a healthy girl and biological paternity was confirmed through analysis of microsatellites. Spontaneous fertility in a young man with severe testotoxicosis and chronic suppression of FSH levels reinforces the key role of high intratesticular testosterone levels in human spermatogenesis.
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Affiliation(s)
- M Cunha-Silva
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - V N Brito
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - D B Macedo
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - D S Bessa
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - C O Ramos
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - L G Lima
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - P S Barroso
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - I J P Arnhold
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - D L Segaloff
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - B B Mendonca
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
| | - A C Latronico
- Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Disciplina de Endocrinologia e Metabologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
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7
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Dhar N, Mohan A, Thakur C, Chandra NR, Dighe RR. Dissecting the structural and functional features of the Luteinizing hormone receptor using receptor specific single chain fragment variables. Mol Cell Endocrinol 2016; 427:1-12. [PMID: 26940038 DOI: 10.1016/j.mce.2016.02.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/27/2016] [Accepted: 02/27/2016] [Indexed: 01/16/2023]
Abstract
The Luteinizing hormone receptor (LHR) has a large extracellular domain (amino acid residues, a.a.1-355) and a transmembrane domain (TMD; a.a. 356-699), essential for hormone binding and signaling, respectively. The LHR hinge region (a.a. 256-355) connects the two domains and acts as an activating switch for the receptor by an unknown mechanism. LHR hinge-specific Single chain fragment variables (ScFv) stimulated cAMP production by the stable and transiently transfected cell lines expressing LHR in a hormone-independent manner and the C-terminal region of LHR hinge (a.a. 313-349) was identified as the probable epitope for one agonistic ScFv. This epitope attained a helical conformation upon agonistic ScFv binding and the activity of the ScFv was dependent on Y331 sulfation. ScFv was also able to activate TMD mutants, D578Y and A593P, reemphasizing the role of TM helix VI in LHR activation.
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Affiliation(s)
- Neha Dhar
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Abhilash Mohan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Chandrani Thakur
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Nagasuma R Chandra
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Rajan R Dighe
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka 560012, India.
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Cahoreau C, Klett D, Combarnous Y. Structure-function relationships of glycoprotein hormones and their subunits' ancestors. Front Endocrinol (Lausanne) 2015; 6:26. [PMID: 25767463 PMCID: PMC4341566 DOI: 10.3389/fendo.2015.00026] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/13/2015] [Indexed: 12/22/2022] Open
Abstract
Glycoprotein hormones (GPHs) are the most complex molecules with hormonal activity. They exist only in vertebrates but the genes encoding their subunits' ancestors are found in most vertebrate and invertebrate species although their roles are still unknown. In the present report, we review the available structural and functional data concerning GPHs and their subunits' ancestors.
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Affiliation(s)
- Claire Cahoreau
- Physiologie de la Reproduction et des Comportements (PRC), Centre National de la Recherche Scientifique, INRA, Nouzilly, France
| | - Danièle Klett
- Physiologie de la Reproduction et des Comportements (PRC), Centre National de la Recherche Scientifique, INRA, Nouzilly, France
| | - Yves Combarnous
- Physiologie de la Reproduction et des Comportements (PRC), Centre National de la Recherche Scientifique, INRA, Nouzilly, France
- *Correspondence: Yves Combarnous, Physiologie de la Reproduction et des Comportements (PRC), Centre National de la Recherche Scientifique, INRA, Nouzilly 37380, France e-mail:
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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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Han X, Tachado SD, Koziel H, Boisvert WA. Leu128(3.43) (l128) and Val247(6.40) (V247) of CXCR1 are critical amino acid residues for g protein coupling and receptor activation. PLoS One 2012; 7:e42765. [PMID: 22936990 PMCID: PMC3427349 DOI: 10.1371/journal.pone.0042765] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 07/10/2012] [Indexed: 12/25/2022] Open
Abstract
CXCR1, a classic GPCR that binds IL-8, plays a key role in neutrophil activation and migration by activating phospholipase C (PLC)β through Gα15 and Gαi which generates diacylglycerol and inositol phosphates (IPs). In this study, two conserved amino acid residues of CXCR1 on the transmembrane domain (TM) 3 and TM6, Leu1283.43 (L128) and Val2476.40 (V247), respectively, were selectively substituted with other amino acids to investigate the role of these conserved residues in CXCR1 activation. Although two selective mutants on Leu128, Leu128Ala (L128A) and Leu128Arg (L128R), demonstrated high binding affinity to IL-8, they were not capable of coupling to G proteins and consequently lost the functional response of the receptors. By contrast, among the four mutants at residue Val247 (TM6.40), replacing Val247 with Ala (V247A) and Asn (V247N) led to constitutive activation of mutant receptors when cotransfected with Gα15. The V247N mutant also constitutively activated the Gαi protein. These results indicate that L128 on TM3.43 is involved in G protein coupling and receptor activation but is unimportant for ligand binding. On the other hand, V247 on TM6.40 plays a critical role in maintaining the receptor in the inactive state, and the substitution of V247 impaired the receptor constraint and stabilized an active conformation. Functionally, there was an increase in chemotaxis in response to IL-8 in cells expressing V247A and V247N. Our findings indicate that Leu1283.43 and Val2476.40 are critical for G protein coupling and activation of signaling effectors, providing a valuable insight into the mechanism of CXCR1 activation.
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Affiliation(s)
- Xinbing Han
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Vascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts, United States of America
- * E-mail: (XH); (WAB)
| | - Souvenir D. Tachado
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Henry Koziel
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - William A. Boisvert
- Department of Vascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts, United States of America
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, United States of America
- * E-mail: (XH); (WAB)
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Abstract
The lutropin receptor (LHR) is a G protein-coupled receptor (GPCR) that mediates the actions of pituitary LH in males and females and that of placental hCG in pregnant women and, therefore, plays an essential role in reproductive physiology. Mutations of the lhcgr gene that result in constitutive activation of the LHR have been shown to be causative of gonadotropin-independent precocious puberty in young boys. Studies on constitutively active mutants (CAMs) of the LHR have been extremely informative in elucidating the roles of the LHR in reproductive physiology as well as in understanding the molecular basis underlying activation of this GPCR. The constitutive activities of hLHR CAMs can be attenuated by introducing mutations into the CAMs that stabilize the resting state of the hLHR or by coexpressing the hLHR CAMs with an hLHR mutant that is stabilized in the resting state, allowing the two forms of the hLHR to heterodimerize. This chapter describes the experimental methods and strategies underlying studies of hLHR CAMs.
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12
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Latronico AC, Hochberg Z. G Protein–Coupled Receptors in Child Development, Growth, and Maturation. Sci Signal 2010; 3:re7. [DOI: 10.1126/scisignal.3143re7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Ana Claudia Latronico
- Developmental Endocrinology Unit, Hormone and Molecular Genetics Laboratory (LIM/42), Hospital das Clinicas, Sao Paulo University Medical School, São Paulo 05403-900, Brazil
| | - Ze’ev Hochberg
- Meyer Children’s Hospital, Rambam Medical Center, Rappaport Faculty of Medicine and Research Institute, Technion–Israel Institute of Technology, P.O. Box 9602, Haifa 31096, Israel
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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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