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Byambaragchaa M, Joo HE, Kim SG, Kim YJ, Park GE, Min KS. Signal Transduction of C-Terminal Phosphorylation Regions for Equine Luteinizing Hormone/Chorionic Gonadotropin Receptor (eLH/CGR). Dev Reprod 2022; 26:1-12. [PMID: 35528321 PMCID: PMC9042392 DOI: 10.12717/dr.2022.26.1.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/04/2022] [Accepted: 02/12/2022] [Indexed: 12/05/2022]
Abstract
This study aimed to investigate the signal transduction of phosphorylation sites
at the carboxyl (C)-terminal region of equine luteinizing hormone/chorionic
gonadotropin receptor (eLH/ CGR). The eLH/CGR has a large extracellular domain
of glycoprotein hormone receptors within the G protein-coupled receptors. We
constructed a mutant (eLH/CGR-t656) of eLH/ CGR, in which the C-terminal
cytoplasmic tail was truncated at the Phe656 residue, through polymerase chain
reaction. The eLH/CGR-t656 removed 14 potential phosphorylation sites in the
intracellular C-terminal region. The plasmids were transfected into Chinese
hamster ovary (CHO)-K1 and PathHunter Parental cells expressing
β-arrestin, and agonist-induced cAMP responsiveness was analyzed. In
CHO-K1 cells, those expressing eLH/CGR-t656 were lower than those expressing
eLH/CGR wild-type (eLH/CGR-wt). The EC50 of the eLH/ CGR-t656 mutant
was approximately 72.2% of the expression observed in eLH/CGR-wt. The maximal
response in eLH/CGR-t656 also decreased to approximately 43% of that observed in
eLH/CGR-wt. However, in PathHunter Parental cells, cAMP activity and maximal
response of the eLH/CGR-t656 mutant were approximately 173.5% and 100.8%,
respectively, of that of eLH/CGR-wt. These results provide evidence that the
signal transduction of C-terminal phosphorylation in eLH/CGR plays a pivotal
role in CHO-K1 cells. The cAMP level was recovered in PathHunter Parental cells
expressing β-arrestin. We suggest that the signal transduction of the
C-terminal region phosphorylation sites is remarkably different depending on the
cells expressing β-arrestin in CHO-K1 cells.
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Affiliation(s)
| | - Hyo-Eun Joo
- Division of Animal Science, School of Animal Life Convergence Sciences, Hankyong National University, Anseong 17579, Korea
| | - Sang-Gwon Kim
- Division of Animal Science, School of Animal Life Convergence Sciences, Hankyong National University, Anseong 17579, Korea
| | - Yean-Ji Kim
- Division of Animal Science, School of Animal Life Convergence Sciences, Hankyong National University, Anseong 17579, Korea
| | - Gyeong-Eun Park
- Division of Animal Science, School of Animal Life Convergence Sciences, Hankyong National University, Anseong 17579, Korea
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Anseong 17579, Korea.,Division of Animal Science, School of Animal Life Convergence Sciences, Hankyong National University, Anseong 17579, Korea
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Kim JM, Byambaragchaa M, Kang MH, Min KS. The C-terminal Phosphorylation Sites of eel Follicle-Stimulating Hormone Receptor are Important Role in the Signal Transduction. Dev Reprod 2018; 22:143-153. [PMID: 30023464 PMCID: PMC6048309 DOI: 10.12717/dr.2018.22.2.143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 06/14/2018] [Accepted: 06/22/2018] [Indexed: 11/17/2022]
Abstract
The large extracellular domain of glycoprotein hormone receptors is a unique feature within the G protein-coupled receptors (GPCRs) family. After interaction with the hormone, the receptor becomes coupled to Gs, which, in turn stimulates adenylyl cyclase and the production of cAMP. Potential phosphorylation sites exist in the C-terminal region of GPCRs. The experiments described herein represent attempts to determine the functions of the eel follicle-stimulating hormone receptor (eelFSHR). We constructed a mutant of eelFSHR, in which the C-terminal cytoplasmic tail was truncated at residue 614 (eelFSHR-t614). The eelFSHR-t614 lacked all potential phosphorylation sites present in the C-terminal region of eelFSHR. In order to obtain the eelFSHR ligand, we produced recombinant follicle-stimulating hormone (rec-eelFSHβ/α) in the CHO-suspension cells. The expression level was 2-3 times higher than that of the transient expression of eelFSH in attached CHO-K1 cells. The molecular weight of the rec-eelFSHβ/α protein was identified to be approximately 34 kDa. The cells expressing eelFSHR-t614 showed an increase in agonist-induced cAMP responsiveness. The maximal cAMP responses of cells expressing eelFSHR-t614 were lower than those of cells expressing eelFSHR-wild type (eelFSHR-WT). The EC50 following C-terminal deletion in CHO-K1 cells was approximately 60.4% of that of eelFSHR-WT. The maximal response in eelFSHR-t614 cells was also drastically lower than that of eelFSHR-WT. We also found similar results in PathHunter Parental cells expressing β-arrestin. Thus, these data provide evidence that the truncation of the C-terminal cytoplasmic tail phosphorylation sites in the eelFSHR greatly decreased cAMP responsiveness and maximal response in both CHO-K1 cells and PathHunter Parental cells expressing β-arrestin.
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Affiliation(s)
- Jeong-Min Kim
- Animal Biotechnology, Graduate School of Future Convergence Technology, Dept. of Animal Life Science, Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Munkhzaya Byambaragchaa
- Animal Biotechnology, Graduate School of Future Convergence Technology, Dept. of Animal Life Science, Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Myung-Hwa Kang
- Dept. of Food Science and Nutrition, Hoseo University, Asan 31499, Korea
| | - Kwan-Sik Min
- Animal Biotechnology, Graduate School of Future Convergence Technology, Dept. of Animal Life Science, Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
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Ohkubo M, Yabu T, Yamashita M, Shimizu A. Molecular cloning of two gonadotropin receptors in mummichog Fundulus heteroclitus and their gene expression during follicular development and maturation. Gen Comp Endocrinol 2013; 184:75-86. [PMID: 23337032 DOI: 10.1016/j.ygcen.2012.12.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 12/13/2012] [Accepted: 12/18/2012] [Indexed: 10/27/2022]
Abstract
Two cDNAs encoding gonadotropin receptors, follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) were cloned from mummichog (Fundulus heteroclitus) ovary. Deduced amino acid sequences of the mummichog FSHR (fhFSHR) and LHR (fhLHR) showed high homologies to teleost FSHRs (77-53%) and teleost LHRs (76-62%), respectively. Both the fhFSHR and fhLHR are composed of a typical structural architecture of glycoprotein hormone receptors consisting of the large N-terminal extracellular domain, the transmembrane domain containing seven cell surface membrane-spanning regions, and the intracellular domain. Functional analysis using HEK293 cells stably expressing the fhFSHR or fhLHR demonstrated that both the receptors are specifically activated by mummichog FSH or LH, respectively. Reverse transcription-polymerase chain reaction revealed that both the fhFSHR and fhLHR were expressed in the ovary, testis, and pituitary, and the fhLHR was also expressed in several extra-gonadal tissues. Real-time quantitative-PCR analysis revealed that the fhFSHR gene was abundantly expressed in developing follicles whereas expression of the fhLHR gene markedly increased in follicles of the final maturational stage. These results indicate that gonadotropin stimulation on follicles is regulated by the two distinct pathways via their cognate receptors.
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Affiliation(s)
- Makoto Ohkubo
- National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama, Kanagawa 236-8648, Japan
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Casas-González P, Scaglia HE, Pérez-Solís MA, Durand G, Scaglia J, Zariñán T, Dias JA, Reiter E, Ulloa-Aguirre A. Normal testicular function without detectable follicle-stimulating hormone. A novel mutation in the follicle-stimulating hormone receptor gene leading to apparent constitutive activity and impaired agonist-induced desensitization and internalization. Mol Cell Endocrinol 2012; 364:71-82. [PMID: 22954680 DOI: 10.1016/j.mce.2012.08.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/15/2012] [Accepted: 08/16/2012] [Indexed: 11/15/2022]
Abstract
Activating mutations in the follicle-stimulating hormone (FSH) receptor (FSHR) gene are rarely detected due to the absence of a clearly defined phenotype, particularly in men. We here report the biochemical features of a novel mutation in the first extracellular loop of the FSHR. The mutation (N431I) was detected in an asymptomatic man exhibiting normal spermatogenesis, suppressed serum FSH, and normal or elevated levels of biochemical markers of FSH action. Employing different experimental strategies on HEK-293 cells transiently expressing the N431I FSHR mutant, we found that the mutation led to decreased cell surface plasma membrane expression of the receptor protein, but conferred a low level of constitutive activity associated with markedly altered agonist-stimulated desensitization and internalization. These latter features may contribute and/or amplify the persistent activation of the receptor in both absence and presence of agonist and provide new insights into opportunities for adjuvant therapies based on disruption of these processes.
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Affiliation(s)
- Patricia Casas-González
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia Luis Castelazo Ayala, Instituto Mexicano del Seguro Social, Mexico 01090, DF, Mexico.
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5
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Kluetzman KS, Thomas RM, Nechamen CA, Dias JA. Decreased degradation of internalized follicle-stimulating hormone caused by mutation of aspartic acid 6.30(550) in a protein kinase-CK2 consensus sequence in the third intracellular loop of human follicle-stimulating hormone receptor. Biol Reprod 2011; 84:1154-63. [PMID: 21270425 DOI: 10.1095/biolreprod.110.087965] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A naturally occurring mutation in follicle-stimulating hormone receptor (FSHR) gene has been reported: an amino acid change to glycine occurs at a conserved aspartic acid 550 (D550, D567, D6.30(567)). This residue is contained in a protein kinase-CK2 consensus site present in human FSHR (hFSHR) intracellular loop 3 (iL3). Because CK2 has been reported to play a role in trafficking of some receptors, the potential roles for CK2 and D550 in FSHR function were evaluated by generating a D550A mutation in the hFSHR. The hFSHR-D550A binds hormone similarly to WT-hFSHR when expressed in HEK293T cells. Western blot analyses showed lower levels of mature hFSHR-D550A. Maximal cAMP production of both hFSHR-D550A as well as the naturally occurring mutation hFSHR-D550G was diminished, but constitutive activity was not observed. Unexpectedly, when (125)I-hFSH bound to hFSHR-D550A or hFSHR-D550G, intracellular accumulation of radiolabeled FSH was observed. Both sucrose and dominant-negative dynamin blocked internalization of radiolabeled FSH and its commensurate intracellular accumulation. Accumulation of radiolabeled FSH in cells transfected with hFSHR-D550A is due to a defect in degradation of hFSH as measured in pulse chase studies, and confocal microscopy imaging revealed that FSH accumulated in large intracellular structures. CK2 kinase activity is not required for proper degradation of internalized FSH because inhibition of CK2 kinase activity in cells expressing hFSHR did not uncouple degradation of internalized radiolabeled FSH. Additionally, the CK2 consensus site in FSHR iL3 is not required for binding because CK2alpha coimmunoprecipitated with hFSHR-D550A. Thus, mutation of D550 uncouples the link between internalization and degradation of hFSH.
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Hirsh L, Ben-Ami I, Freimann S, Dantes A, Tajima K, Kotsuji F, Amsterdam A. Desensitization to gonadotropic hormones: a model system for the regulation of a G-protein-coupled receptor with 7-transmembrane spanning regions. Biochem Biophys Res Commun 2004; 326:1-6. [PMID: 15567144 DOI: 10.1016/j.bbrc.2004.10.168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Indexed: 11/24/2022]
Abstract
Gonadotropic hormone, luteinizing hormone, and follicle-stimulating hormone exert their effect via activation of G-coupled receptors, which activate the hormone sensitive adenylyl cyclase, protein kinase A, and cyclic AMP responsive elements. This activation leads to specific de novo synthesis of steroidogenic factors and steroidogenic enzymes. In normal cells and following activation of this signaling pathway, desensitization period will be followed. This down-regulation, which was studied in detail for the last three decays, was found to take place at various steps of these signal transduction pathways as well as at different kinetics. A common and diverse feature of the mechanism of desensitization in other G-coupled-7-transmembrane receptor system is also discussed.
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Affiliation(s)
- Liron Hirsh
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel
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Cohen BD, Bariteau JT, Magenis LM, Dias JA. Regulation of follitropin receptor cell surface residency by the ubiquitin-proteasome pathway. Endocrinology 2003; 144:4393-402. [PMID: 12960054 DOI: 10.1210/en.2002-0063] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Little is known of the normal physiological processes that govern the cell surface residency of the human follitropin receptor (hFSHR), a G protein-coupled receptor expressed in the ovary and testis. In the hFSHR, the third intracellular (3i) loop is considered to be pivotal in attenuation of ligand activation, particularly internalization. To gain a better understanding of these processes, we used a yeast-based interaction trap to identify cytoplasmic proteins in a human ovarian cDNA library that interacted with the hFSHR 3i loop. Among the cDNA identified, four encoded isoforms of ubiquitin. Immunoprecipitated hFSHR probed with an antiubiquitin antibody revealed that the receptor is ubiquitinated, although not exclusively on the 3i loop. Cell-surface hFSHR levels increased when expressed at nonpermissive temperature in a temperature-sensitive, ubiquitination-defective cell line. Similarly, after treatment with proteasome inhibitors, HEK293 cells stably transfected with an hFSHR expression plasmid showed an increase in follitropin binding. Proteasome inhibitors did not affect the rate of FSH internalization when receptors were saturated before internalization was measured. In contrast, internalization decreased when binding experiments were performed under nonequilibrium conditions. A mutant hFSHR-K555R, which removes the only lysine in the 3i loop available for ubiquitination, was still ubiquitinated, illustrating that, although the third loop enables and interaction with ubiquitin, it is not the sole site of ubiquitination. These observations are consistent with a role for ubiquitination in the regulation of hFSHR cell surface residency. Additionally, it can be inferred that a sequence in the 3i loop is involved in regulating receptor ubiquitination and internalization.
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Affiliation(s)
- Brian D Cohen
- Laboratory of Clinical and Experimental Endocrinology and Immunology, Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, New York 12208, USA
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8
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Sartor O, Dineen MK, Perez-Marreno R, Chu FM, Carron GJ, Tyler RC. An eight-month clinical study of LA-2575 30.0 mg: a new 4-month, subcutaneous delivery system for leuprolide acetate in the treatment of prostate cancer. Urology 2003; 62:319-23. [PMID: 12893343 DOI: 10.1016/s0090-4295(03)00330-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To investigate the safety, efficacy, and pharmacokinetics of a new 4-month subcutaneous depot of leuprolide acetate in patients with prostate cancer. METHODS Ninety patients diagnosed with adenocarcinoma of the prostate were enrolled in an open-label, multicenter study. LA-2575 30.0 mg was administered subcutaneously once every 4 months for 8 months. The primary efficacy parameter was a serum testosterone level of 50 ng/dL or less. The pharmacokinetics of leuprolide acetate were analyzed in the first 24 enrolled patients. The values are reported as the mean +/- standard error. RESULTS Of 90 enrolled patients, 82 (91%) completed the 8-month study. Eight patients voluntarily withdrew from the study for the following reasons: nonmedical reasons (n = 3), treatment-related adverse events (n = 3), disease progression (n = 1), and cardiovascular disease (n = 1). By day 28, 85 (94%) of the 90 patients had achieved a serum testosterone level less than 50 ng/dL. At study completion, 88 (98%) of the 90 patients had a testosterone value less than the castrate level (mean 12.4 +/- 0.8 ng/dL), with 81 (90%) at less than 20 ng/dL. From baseline to month 6, the mean luteinizing hormone level had decreased from 7.51 +/- 0.69 mIU/mL to 0.12 +/- 0.02 mIU/mL. The mean prostate-specific antigen level had decreased 90% from 13.2 +/- 2.0 ng/mL at baseline to 1.3 +/- 0.3 ng/mL at 8 months. No clinically significant flare reactions were observed. The most common treatment-related adverse event was mild hot flashes. CONCLUSIONS LA-2575 30.0-mg depot consistently produced and maintained safe and effective suppression of serum testosterone, with total serum testosterone concentrations well below the medical castrate level of less than 50 ng/dL.
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Affiliation(s)
- Oliver Sartor
- Louisiana State University School of Medicine, New Orleans, Louisiana, USA
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Chu FM, Jayson M, Dineen MK, Perez R, Harkaway R, Tyler RC. A clinical study of 22.5 mg. La-2550: A new subcutaneous depot delivery system for leuprolide acetate for the treatment of prostate cancer. J Urol 2002; 168:1199-203. [PMID: 12187267 DOI: 10.1016/s0022-5347(05)64625-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE The safety, efficacy and pharmacokinetics of a unique 3-month subcutaneous depot of leuprolide acetate were investigated in patients with prostate cancer. MATERIALS AND METHODS This open label, noncomparative, 6-month multicenter study enrolled 117 patients diagnosed with adenocarcinoma of the prostate. LA-2550 (22.5 mg. depot) (Atrix Laboratories, Fort Collins, Colorado) was administered subcutaneously once every 3 months. The primary efficacy parameter was serum testosterone 50 ng./dl. or less. Pharmacokinetics were analyzed in a subset of 22 patients. RESULTS Of the 117 enrolled patients 111 (98%) completed the 6-month study. Five patients withdrew for nontreatment related events and 1 was withdrawn because he received less than a full dose of the study drug. By day 28, 98% of patients had serum testosterone 50 ng./dl. or less and 84% had achieved 20 ng./dl. or less. By day 35 all patients had 50 ng./dl. or less testosterone. A patient with a breakthrough response after testosterone suppression on day 49 (112 ng./dl.) regained suppression (27 ng./dl.) 14 days after the second injection (day 98). At study completion all patients had 50 ng./dl. or less testosterone (mean plus or minus standard error of mean 10.1 +/- 0.07) and 104 of the 111 (94%) had 20 ng./dl. or less. From baseline to month 6 mean luteinizing hormone decreased from 9.2 +/- 1.1 to 0.08 +/- 0.01 mIU/ml. and mean prostate specific antigen decreased more than 98%. No flare reactions were observed and patient assessments of bone pain and urinary symptoms were unchanged. The most common treatment related adverse event was hot flashes, which were mild in 57% of cases, moderate in 12% and severe in 0%. CONCLUSIONS LA-2550 (22.5 mg. depot) produced and maintained safe and effective suppression of serum testosterone to well below the medical castrate level of 50 ng./dl. or less.
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Affiliation(s)
- Franklin M Chu
- San Bernardino Urological Associates, San Bernardino, California, USA
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10
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A Clinical Study Of 22.5 mg. La-2550: A New Subcutaneous Depot Delivery System For Leuprolide Acetate For The Treatment Of Prostate Cancer. J Urol 2002. [DOI: 10.1097/00005392-200209000-00088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
The gonadotropic hormones, FSH and LH exert a major effect on ovarian and testicular function through interaction with specific seven-transmembrane domain glycoprotein receptors. Desensitization to the hormones, which can occur both in vivo and in vitro, is essential for prevention of overstimulation of the gonadal cells. The long-term process of desensitization to the gonadotropic hormones is probably mediated, in part, by extensive clustering and internalization of the hormone-receptor complex. Short-term desensitization may occur as a result of phosphorylation of serine or threonine residues on the receptor molecules, although a specific receptor kinase has not yet been identified. Recently, we have discovered a novel mechanism of gonadotropin desensitization, which is exerted by down-regulation of StAR expression and steroidogenesis mediated by MAPK activation as a result of hormone-receptor interaction, cAMP accumulation and PKA activation. Thus, PKA not only mediates gonadotropin-induced steroidogenesis, it also activates the down-regulation mechanism that can silence steroidogenesis under certain conditions. Moreover, our findings raise the possibility that activation or inhibition of ERK by other pathways could be an important mechanism for diminution or amplification of gonadotropin-stimulated steroidogenesis. This could contribute to functional luteolysis, a process in which luteinized granulosa cells show reduced sensitivity to LH despite maintenance of LH receptors, or to up-regulation of the steroidogenic machinery during luteinization of granulosa cells.
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Affiliation(s)
- Abraham Amsterdam
- Department of Molecular Cell Biology, The Weizmann Institute of Science, 76100, Rehovot, Israel.
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12
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Affiliation(s)
- Jennifer R Wood
- Center for Research on Reproduction and Women's Health, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA
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Clément F, Monniaux D, Stark J, Hardy K, Thalabard JC, Franks S, Claude D. Mathematical model of FSH-induced cAMP production in ovarian follicles. Am J Physiol Endocrinol Metab 2001; 281:E35-53. [PMID: 11404221 DOI: 10.1152/ajpendo.2001.281.1.e35] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the terminal part of their development, ovarian follicles become totally dependent on gonadotropin supply to pursue their growth and maturation. Both gonadotropins, follicle-stimulating hormone (FSH) and luteining hormone (LH), operate mainly through stimulatory G protein-coupled receptors, their signal being transduced by the activation of the enzyme adenylyl cyclase and the production of second-messenger cAMP. In this paper, we develop a mathematical model of the dynamics of the coupling between FSH receptor stimulation and cAMP synthesis. This model takes the form of a set of nonlinear, ordinary differential equations that describe the changes in the different states of FSH receptors (free, bound, phosphorylated, and internalized), coupling efficiency (activated adenylyl cyclase), and cAMP response. Classical analysis shows that, in the case of constant FSH signal input, the system converges to a unique, stable equilibrium state, whose properties are here investigated. The system also appears to be robust to nonconstant input. Particular attention is given to the influence of biologically relevant parameters on cAMP dynamics.
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Affiliation(s)
- F Clément
- Institut National de Recherche en Informatique et Automatique, Unité de Recherche de Rocquencourt, Domaine de Voluceau, Rocquencourt, 78153 Le Chesnay Cedex, France.
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14
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Babu PS, Krishnamurthy H, Chedrese PJ, Sairam MR. Activation of extracellular-regulated kinase pathways in ovarian granulosa cells by the novel growth factor type 1 follicle-stimulating hormone receptor. Role in hormone signaling and cell proliferation. J Biol Chem 2000; 275:27615-26. [PMID: 10869352 DOI: 10.1074/jbc.m003206200] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Follicle-stimulating hormone (FSH) regulated growth and function of the ovarian follicle was previously thought to be mediated solely through activation of G(s)-coupled receptors. In this study, we show for the first time that this function is predominantly mediated through the alternatively spliced and novel growth factor type 1 receptor (oFSH-R3) that is also present in the ovary. Immortalized granulosa cells lacking endogenous FSH receptors, when transfected with either oFSH-R3 cDNA (JC-R3) or the G(s)-coupled oFSH-R1 (JC-R1), expressed the corresponding glycosylated receptor. In JC-R3 or JC-R1 cells labeled with bromodeoxyuridine or [(3)H]thymidine, FSH stimulated the cells to progress through S-phase and divide. The growth promoting effect of recombinant FSH in JC-R3 cells was preceded by the rapid activation of ERK1 and ERK2. This effect was hormone-specific and transient. In JC-R3 cells inhibitors like calphostin C, PD98059, Ag 18, or calcium chelators EGTA or 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/AM inhibited both mitogen-activated protein kinase activation and bromodeoxyuridine incorporation. FSH induced phosphorylation of the FSH-R3 receptor was blocked by pretreating cells with calphostin C. There was no cAMP induction by FSH in JC-R3 cells. The cAMP independent growth promoting effect of FSH is mediated by activation of Ca(2+) and mitogen-activated protein kinase-dependent pathways. Thus, alternative splicing of a G-protein coupled receptor creates the expression of a novel receptor motif that can mediate a widely recognized function of the glycoprotein hormone.
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Affiliation(s)
- P S Babu
- Molecular Reproduction Research Laboratory, Clinical Research Institute of Montreal, Montreal, Québec H2W 1R7, Canada
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15
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Oki N, Takahashi SI, Hidaka H, Conti M. Short term feedback regulation of cAMP in FRTL-5 thyroid cells. Role of PDE4D3 phosphodiesterase activation. J Biol Chem 2000; 275:10831-7. [PMID: 10753877 DOI: 10.1074/jbc.275.15.10831] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Together with a transient accumulation of intracellular cAMP, thyrotropin (TSH) stimulation of the FRTL-5 thyroid cell induces phosphorylation and activation of a cAMP-specific phosphodiesterase (PDE4D3). Here we have investigated the impact of PDE4D3 activation on hormone responsiveness. Stimulation of FRTL-5 cells with TSH caused an increase in PDE activity within 3 min, with a maximal stimulation reached after 5 min. Preincubation with the protein kinase A (PKA) inhibitor H89 or (R(p))-cAMPS, but not with the inactive isomer H85, blocked this activation. Preincubation with PKA inhibitors also blocked the shift in mobility of the PDE4D3 protein. Under these conditions, H89, but not H85, potentiated the cAMP accumulation induced by TSH. Incubation of FRTL-5 cells with the PKA activator 8-(4-chlorophenylthio)adenosine-cAMP caused an increase in PDE activity and a decrease in the endogenous cAMP, confirming the presence of a PKA-PDE feedback loop. MA-10 Leydig tumor cells stably transfected with either a wild type PDE4D3 or a PDE4D3 with mutations in the PKA phosphorylation sites showed an increase in PDE activity when compared with control cells. Human choriogonadotropin or Bt(2)cAMP treatment induced a stimulation of PDE activity in cells transfected with wild type PDE4D3, whereas the activation was absent in mutant- and control-transfected cells. The increase in cAMP accumulation elicited by human choriogonadotropin was reduced in cells transfected with the wild type PDE4D3, but not in cells transfected with the mutant PDE. Rolipram, a specific inhibitor of PDE4, restored the cAMP accumulation in the PDE4D3-transfected cells. These data provide evidence that a rapid activation of PDE4D3 is one of the mechanisms determining the intensity of the cAMP signal.
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Affiliation(s)
- N Oki
- Division of Reproductive Biology, Department of Gynecology, Stanford University School of Medicine, Stanford, California 94305-5317, USA
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Larrea F, Sánchez-González S, Méndez I, García-Becerra R, Cabrera V, Ulloa-Aguirre A. G protein-coupled receptors as targets for prolactin actions. Arch Med Res 1999; 30:532-43. [PMID: 10714368 DOI: 10.1016/s0188-0128(99)00056-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Prolactin (PRL) is known to be involved in a wide range of biological functions including osmoregulation, lactation, reproduction, and immunomodulation. The first step in PRL action involves its interaction with a specific membrane receptor that belongs to the cytokine receptor superfamily. In spite of the lack of a kinase domain, receptors of the cytokine superfamily induce tyrosine phosphorylation of cellular substrates including the receptors. The role of PRL in female reproductive functions is well known and a direct effect on ovarian and testicular steroidogenesis has been established. In the ovary, PRL binds to a specific membrane receptor and exerts an inhibitory effect on follicular steroidogenesis. This effect is the result of an impairment involving FSH stimulation of G protein-coupled receptors (GPCR) and cyclic AMP-mediated activation of aromatase cytochrome P450 gene expression. This observation may indicate a direct connection between tyrosine phosphorylation and follicle-stimulating hormone (FSH) receptor (FSHR) transduction pathways, as is the case for growth factor receptors with intrinsic tyrosine kinase activity, which share several downstream signaling elements with GPCRs. Some studies leading to our understanding of these pathways are reviewed.
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Affiliation(s)
- F Larrea
- Departamento de Biología de la Reproducción, Instituto Nacional de la Nutrición Salvador Zubirán, México, D.F., Mexico.
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Troispoux C, Guillou F, Elalouf JM, Firsov D, Iacovelli L, De Blasi A, Combarnous Y, Reiter E. Involvement of G protein-coupled receptor kinases and arrestins in desensitization to follicle-stimulating hormone action. Mol Endocrinol 1999; 13:1599-614. [PMID: 10478849 DOI: 10.1210/mend.13.9.0342] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
FSH rapidly desensitizes the FSH-receptor (FSH-R) upon binding. Very little information is available concerning the regulatory proteins involved in this process. In the present study, we investigated whether G protein-coupled receptor kinases (GRKs) and arrestins have a role in FSH-R desensitization, using a mouse Ltk 7/12 cell line stably overexpressing the rat FSH-R as a model. We found that these cells, which express GRK2, GRK3, GRK5, and GRK6 as well as beta-arrestins 1 and 2 as detected by RT-PCR and by Western blotting, were rapidly desensitized in the presence of FSH. Overexpression of GRKs and/or beta-arrestins in Ltk 7/12 cells allowed us to demonstrate 1) that GRK2, -3, -5, -6a, and -6b inhibit the FSH-R-mediated signaling (from 71% to 96% of maximal inhibition depending on the kinase, P < 0.001); 2) that beta-arrestins 1 or 2 also decrease the FSH action when overexpressed (80% of maximal inhibition, P < 0.01) whereas dominant negative beta-arrestin 2 [319-418] potentiates it 8-fold (P < 0.001); 3) that beta-arrestins and GRKs (except GRK6a) exert additive inhibition on FSH-induced response; and 4) that FSH-R desensitization depends upon the endogenous expression of GRKs, since there is potentiation of the FSH response (2- to 3-fold, P < 0.05) with antisenses cDNAs for GRK2, -5, and -6, but not GRK3. Our results show that the desensitization of the FSH-induced response involves the GRK/arrestin system.
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Affiliation(s)
- C Troispoux
- INRA/CNRS URA 1291, Station de Physiologie de la Reproduction des Mammifères Domestiques, Nouzilly, France
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Nakamura K, Hipkin RW, Ascoli M. The agonist-induced phosphorylation of the rat follitropin receptor maps to the first and third intracellular loops. Mol Endocrinol 1998; 12:580-91. [PMID: 9544993 DOI: 10.1210/mend.12.4.0087] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Previous results from this laboratory have shown that the rat FSH receptor (rFSHR) becomes phosphorylated on S/T residues upon stimulation of transfected cells with human (h)FSH and that a truncation of the C-terminal tail that removes 12 of the 25 intracellular S/T residues does not affect phosphorylation. Based on the results of phosphopeptide-mapping experiments we analyzed three new mutants. rFSHR-1L and rFSHR-3L were constructed by mutating the S/T residues in the first intracellular loop or the third intracellular loop, respectively. rFSHR-(3L+CT) was constructed by mutating all the S/T residues in the third loop as well as S624, the only C-terminal tail residue that was not previously eliminated as a potential phosphorylation site. All mutants were biologically active. The agonist-induced phosphorylation of rFSHR-3L and rFSHR-(3L+CT) were partially reduced, while that of rFSHR-1L was almost completely lost. The agonist-induced uncoupling of rFSHR-1L and rFSHR-3L are retarded to about the same extent, while the agonist-induced internalization is retarded only in rFSHR-1L. Four major conclusions can be made from the present studies: 1) the phosphorylated rFSHR is a common molecular intermediate in agonist-induced uncoupling and internalization; 2) agonist-induced phosphorylation of the rFSHR maps to the first and third intracellular loops; 3) the phosphorylation of the third intracellular loop facilitates agonist-induced uncoupling but is not necessary for agonist-induced internalization; 4) agonist-induced internalization is facilitated by phosphorylation but it is not known if only the first loop, only the third loop, or both the first and third loops need to be phosphorylated for this response.
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Affiliation(s)
- K Nakamura
- Department of Pharmacology, The University of Iowa College of Medicine, Iowa City 52242, USA
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Simoni M, Gromoll J, Nieschlag E. The follicle-stimulating hormone receptor: biochemistry, molecular biology, physiology, and pathophysiology. Endocr Rev 1997; 18:739-73. [PMID: 9408742 DOI: 10.1210/edrv.18.6.0320] [Citation(s) in RCA: 178] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M Simoni
- Institute of Reproductive Medicine of the University, Münster, Germany
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