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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, Seong HK, Choi SH, Kim DJ, Kang MH, Min KS. Constitutively Activating Mutants of Equine LH/CGR Constitutively Induce Signal Transduction and Inactivating Mutations Impair Biological Activity and Cell-Surface Receptor Loss In Vitro. Int J Mol Sci 2021; 22:ijms221910723. [PMID: 34639064 PMCID: PMC8509413 DOI: 10.3390/ijms221910723] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 12/26/2022] Open
Abstract
The signal transduction of the equine lutropin/choriogonadotropin receptor (eLH/CGR) is unclear in naturally occurring activating/inactivating mutants of this receptor, which plays an important role in reproductive physiology. We undertook the present study to determine whether conserved structurally related mutations in eLH/CGR exhibit similar mechanisms of signal transduction. We constructed four constitutively activating mutants (M398T, L457R, D564G, and D578Y) and three inactivating mutants (D405N, R464H, and Y546F); measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary cells; and investigated cell-surface receptor loss using an enzyme-linked immunosorbent assay in human embryonic kidney 293 cells. The eLH/CGR-L457R-, -D564G-, and -D578Y-expressing cells exhibited 16.9-, 16.4-, and 11.2-fold increases in basal cAMP response, respectively. The eLH/CGR-D405N- and R464H-expressing cells presented a completely impaired signal transduction, whereas the Y546F-expressing cells exhibited a small increase in cAMP response. The cell-surface receptor loss was 1.4- to 2.4-fold greater in the activating-mutant-expressing cells than in wild-type eLH/CGR-expressing cells, but was completely impaired in the D405N- and Y546F-expressing cells, despite treatment with a high concentration of agonist. In summary, the state of activation of eLH/CGR influenced agonist-induced cell-surface receptor loss, which was directly related to the signal transduction of constitutively activating mutants.
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Affiliation(s)
- Munkhzaya Byambaragchaa
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
| | - Hoon-Ki Seong
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
| | - Seung-Hee Choi
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea;
| | - Dae-Jung Kim
- Jeju Fisheries Research Institute, National Institute of Fisheries Science (NIFS), Jeju 63610, Korea;
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan 31499, Korea;
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea;
- Correspondence: ; Tel.: +82-31-670-5421; Fax: +82-31-670-5417
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Byambaragchaa M, Ahn TY, Choi SH, Kang MH, Min KS. Functional characterization of naturally-occurring constitutively activating/inactivating mutations in equine follicle-stimulating hormone receptor (eFSHR). Anim Biosci 2021; 35:399-409. [PMID: 34474536 PMCID: PMC8902225 DOI: 10.5713/ab.21.0246] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/12/2021] [Indexed: 11/27/2022] Open
Abstract
Objective Follicle-stimulating hormone (FSH) is the central hormone involved in mammalian reproduction, maturation at puberty, and gamete production that mediates its function by control of follicle growth and function. The present study investigated the mutations involved in the regulation of FSH receptor (FSHR) activation. Methods We analyzed seven naturally-occurring mutations that were previously reported in human FSHR (hFSHR), in the context of equine FSHR (eFSHR); these include one constitutively activation variant, one allelic variant, and five inactivating variants. These mutations were introduced into wild-type eFSHR (eFSHR-wt) sequence to generate mutants that were designated as eFSHR-D566G, -A306T, -A189V, -N191I, -R572C, -A574V, and -R633H. Mutants were transfected into PathHunter EA-parental CHO-K1 cells expressing β-arrestin. The biological function of mutants was analyzed by quantitating cAMP accumulation in cells incubated with increasing concentrations of FSH. Results Cells expressing eFSHR-D566G exhibited an 8.6-fold increase in basal cAMP response, as compared to that in eFSHR-wt. The allelic variation mutant eFSHR-A306T was not found to affect the basal cAMP response or EC50 levels. On the other hand, eFSHR-D566G and eFSHR-A306T displayed a 1.5- and 1.4-fold increase in the maximal response, respectively. Signal transduction was found to be completely impaired in case of the inactivating mutants eFSHR-A189V, -R572C, and -A574V. When compared with eFSHR-wt, eFSHR-N191I displayed a 5.4-fold decrease in the EC50 levels (3910 ng/mL) and a 2.3-fold decrease in the maximal response. In contrast, cells expressing eFSHR-R633H displayed in a similar manner to that of the cells expressing the eFSHR-wt on signal transduction and maximal response. Conclusion The activating mutant eFSHR-D566G greatly enhanced the signal transduction in response to FSH, in the absence of agonist treatment. We suggest that the state of activation of the eFSHR can modulate its basal cAMP accumulation.
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Affiliation(s)
- Munkhzaya Byambaragchaa
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea
| | - Tae-Young Ahn
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea
| | - Seung-Hee Choi
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan 31499, Korea
| | - Kwan-Sik Min
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea.,School of Animal Life Convergence Science, Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
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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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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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Senniappan S, Wood D, Hakeem V, Stoneham S, Freeman A, Dattani M. Gonadotrophin-independent precocious puberty associated with later diagnosis of testicular embryonal carcinoma. Horm Res Paediatr 2015; 82:272-7. [PMID: 25012595 DOI: 10.1159/000362187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 03/04/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Testicular tumours are very rare in children. Germ cell tumours (GCTs) account for the majority of testicular tumours in young people, and embryonal carcinomas are a common component of GCTs in adolescents. CASE PRESENTATION A 9.8-year-old boy presented with the development of pubic and facial hair over a period of 2 years. He had a growth spurt and examination revealed pubertal staging of G4 P4 A2 with a 6-mls testis on the right and a 4-mls testis on the left. Investigations revealed suppressed gonadotrophins, a testosterone concentration of 10.3 nmol/l and normal 17-hydroxyprogesterone and adrenal androgen levels. Tumour markers were negative. Following treatment with anastrazole, his height velocity slowed down. At the age of 13.7 years, his treatment was stopped. At the age of 14.8 years, he presented with a grossly enlarged right testis and elevated beta human chorionic gonadotrophin (>1,400 IU/l). He underwent right orchidectomy and histology revealed an embryonal carcinoma with no vascular invasion. Analysis of luteinizing hormone/choriogonadotrophin receptor revealed no mutation. CONCLUSION We present a case of testicular embryonal carcinoma in a boy who had presented 5 years before with features suggestive of gonadotrophin-independent precocious puberty.
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Affiliation(s)
- Senthil Senniappan
- Developmental Endocrinology Research Group, Clinical and Molecular Genetics Unit, Institute of Child Health, University College London, London, UK
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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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Choi D. The consequences of mutations in the reproductive endocrine system. Dev Reprod 2012; 16:235-51. [PMID: 25949097 PMCID: PMC4282240 DOI: 10.12717/dr.2012.16.4.235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 12/01/2012] [Accepted: 12/10/2012] [Indexed: 01/03/2023]
Abstract
The reproductive activity in male mammals is well known to be regulated by the hypothalamus-pituitary- gonad axis. The hypothalamic neurons secreting gonadotropin releasing hormone (GnRH) govern the reproductive neuroendocrine system by integrating all the exogenous information impinging on themselves. The GnRH synthesized and released from the hypothalamus arrives at the anterior pituitary through the portal vessels, provoking the production of the gonadotropins(follicle-stimulating hormone (FSH) and luteinizing hormone (LH)) at the same time. The gonadotropins affect the gonads to promote spermatogenesis and to secret testosterone. Testosterone acts on the GnRH neurons by a feedback loop through the circulatory system, resulting in the balance of all the hormones by regulating reproductive activities. These hormones exert their effects by acting on their own receptors, which are included in the signal transduction pathways as well. Unexpected aberrants are arised during this course of action of each hormone. This review summarizes these abnormal phenomena, including various mutations of molecules and their actions related to the reproductive function.
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Affiliation(s)
- Donchan Choi
- Dept. of Life Science, College of Environmental Sciences, Yong-In University, Yongin 449-714, Korea
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Bonde MM, Yao R, Ma JN, Madabushi S, Haunsø S, Burstein ES, Whistler JL, Sheikh SP, Lichtarge O, Hansen JL. An angiotensin II type 1 receptor activation switch patch revealed through evolutionary trace analysis. Biochem Pharmacol 2010; 80:86-94. [PMID: 20227396 DOI: 10.1016/j.bcp.2010.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 02/08/2010] [Accepted: 03/04/2010] [Indexed: 12/21/2022]
Abstract
Seven transmembrane (7TM) or G protein-coupled receptors constitute a large superfamily of cell surface receptors sharing a structural motif of seven transmembrane spanning alpha helices. Their activation mechanism most likely involves concerted movements of the transmembrane helices, but remains to be completely resolved. Evolutionary Trace (ET) analysis is a computational method, which identifies clusters of functionally important residues by integrating information on evolutionary important residue variations with receptor structure. Combined with known mutational data, ET predicted a patch of residues in the cytoplasmic parts of TM2, TM3, and TM6 to form an activation switch that is common to all family A 7TM receptors. We tested this hypothesis in the rat Angiotensin II (Ang II) type 1a (AT1a) receptor. The receptor has important roles in the cardiovascular system, but has also frequently been applied as a model for 7TM receptor activation and signaling. Six mutations: F66A, L67R, L70R, L119R, D125A, and I245F were targeted to the putative switch and assayed for changes in activation state by their ligand binding, signaling, and trafficking properties. All but one receptor mutant (that was not expressed well) displayed phenotypes associated with changed activation state, such as increased agonist affinity or basal activity, promiscuous activation, or constitutive internalization highlighting the importance of testing different signaling pathways. We conclude that this evolutionary important patch mediates interactions important for maintaining the inactive state. More broadly, these observations in the AT1 receptor are consistent with computational predictions of a generic role for this patch in 7TM receptor activation.
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Affiliation(s)
- Marie Mi Bonde
- Laboratory for Molecular Cardiology, The Danish National Research Foundation Centre for Cardiac Arrhythmia, The Heart Centre, Copenhagen University Hospital, Rigshospitalet, Juliane Mariesvej 20, section 9312, DK-2100 Copenhagen, Denmark
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Kuijper TM, Ruigrok-Ritstier K, Verhoef-Post M, Piersma D, Bruysters MW, Berns EM, Themmen AP. LH receptor gene expression is essentially absent in breast tumor tissue: implications for treatment. Mol Cell Endocrinol 2009; 302:58-64. [PMID: 19356624 PMCID: PMC2692988 DOI: 10.1016/j.mce.2008.12.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/08/2008] [Accepted: 12/20/2008] [Indexed: 12/21/2022]
Abstract
Worldwide, breast cancer is the most frequently occurring malignancy in women. Early age at full term pregnancy has a protective effect against breast cancer. Evidence coming from a rat breast cancer model suggests a possible role for the pregnancy hormone hCG, a ligand of the LH receptor, as a mediator for this effect. In a previous study, we found that a common polymorphism in the LH receptor associates with tumor progression in premenopausal breast cancer patients, as carriers of the variant receptor showed a shorter disease free survival compared to non-carriers. How hCG and its receptor exert their effects on breast cancer, however, is unclear. One possibility is that these effects take place through LH receptors present in the ovaries, thereby influencing steroid hormone production. Another possibility is that the effects take place through LH receptors present in breast tumor cells themselves, as some studies have detected the receptor in both normal and neoplastic breast tissues and in breast cancer cell lines. To investigate whether a direct effect of LH signaling in breast cancer is likely, we measured LH receptor mRNA expression levels in 1551 breast tumors and 42 different human breast cancer cell lines using a qRT-PCR with a wide dynamic range. In addition, associations between LH receptor expression and clinico-pathologic factors were investigated. Assay validation showed that as little as ?10 copies per reaction volume of LH receptor cDNA could still be detected by our assay. We show that LH receptors are undetectable in 62% of breast tumor samples and 41 of 42 breast cancer cell lines. For the remaining samples we found expression levels to be very low. Although low, expression of the LH receptor appears to be associated with normal breast cells, favorable tumor characteristics and low tumor percentage. Since expression of the LH receptor in breast cancer cells is very low, it almost excludes the possibility of direct signaling effects. We therefore conclude that signaling effects of the LH receptor on breast cancer most likely take place by an indirect pathway through the ovaries.
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Affiliation(s)
- T. Martijn Kuijper
- Department of Internal Medicine, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | | | - Miriam Verhoef-Post
- Department of Internal Medicine, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Djura Piersma
- Department of Internal Medicine, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Martijn W.P. Bruysters
- Department of Internal Medicine, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Els M.J.J. Berns
- Department of Medical Oncology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Axel P.N. Themmen
- Department of Internal Medicine, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
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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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Bruysters M, Verhoef-Post M, Themmen APN. Asp330 and Tyr331 in the C-terminal cysteine-rich region of the luteinizing hormone receptor are key residues in hormone-induced receptor activation. J Biol Chem 2008; 283:25821-8. [PMID: 18641392 DOI: 10.1074/jbc.m804395200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The luteinizing hormone (LH) receptor plays an essential role in male and female gonadal function. Together with the follicle-stimulating hormone (FSH) and thyroid stimulating hormone (TSH) receptors, the LH receptor forms the family of glycoprotein hormone receptors. All glycoprotein hormone receptors share a common modular topography, with an N-terminal extracellular ligand binding domain and a C-terminal seven-transmembrane transduction domain. The ligand binding domain consists of 9 leucine-rich repeats, flanked by N- and C-terminal cysteine-rich regions. Recently, crystal structures have been published of the extracellular domains of the FSH and TSH receptors. However, the C-terminal cysteine-rich region (CCR), also referred to as the "hinge region," was not included in these structures. Both structure and function of the CCR therefore remain unknown. In this study we set out to characterize important domains within the CCR of the LH receptor. First, we mutated all cysteines and combinations of cysteines in the CCR to identify the most probable disulfide bridges. Second, we exchanged large parts of the LH receptor CCR by its FSH receptor counterparts, and characterized the mutant receptors in transiently transfected HEK 293 cells. We zoomed in on important regions by focused exchange and deletion mutagenesis followed by alanine scanning. Mutations in the CCR specifically decreased the potencies of LH and hCG, because the potency of the low molecular weight agonist Org 41841 was unaffected. Using this unbiased approach, we identified Asp(330) and Tyr(331) as key amino acids in LH/hCG mediated signaling.
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Affiliation(s)
- Martijn Bruysters
- Department of Internal Medicine, Erasmus MC, P. O. Box 2040, 3000 CA Rotterdam, The Netherlands
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Bruysters M, Christin-Maitre S, Verhoef-Post M, Sultan C, Auger J, Faugeron I, Larue L, Lumbroso S, Themmen APN, Bouchard P. A new LH receptor splice mutation responsible for male hypogonadism with subnormal sperm production in the propositus, and infertility with regular cycles in an affected sister. Hum Reprod 2008; 23:1917-23. [PMID: 18508780 DOI: 10.1093/humrep/den180] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Inactivating LH receptor (LHR) mutations have been described so far in men as well as in women. Phenotypes in men have been variable with in nearly all cases impairment of sex differentiation or azoospermia. We report a milder reproductive phenotype both in a male patient and his sister. METHODS AND RESULTS We describe a family that carries a homozygous mutation G-->A at position -1 at the intron 10-exon 11 boundary of the LHR gene. The male patient presented with delayed puberty, micropenis and oligospermia. Two of his sisters were homozygous for the same mutation and were infertile. Surprisingly, one of them was found to have had regular ovarian cycles for years and showed normal LH values (6.5 and 10.6 mIU/ml for LH and FSH, respectively). In vitro analysis showed that this altered splicing resulted in an LHR from which eight amino acids are deleted from the extracellular domain (Delta Tyr(317)-Ser(324)). In vitro expression has shown that the receptor was expressed and capable of LH-induced signaling, albeit with reduced potency (P < 0.001). CONCLUSIONS LHR mutations may represent an underestimated cause of infertility in women, in addition to being responsible for male hypogonadism with reduced spermatogenesis.
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Affiliation(s)
- M Bruysters
- Department of Internal Medicine, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
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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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