| Rat gonadotropin-releasing hormone receptor expressed in insect cells induces activation of adenylyl cyclase. | |
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MedLine Citation:
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PMID: 9484907 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Increasing evidence exist that multiple G proteins mediate the effects of gonadotropin-releasing hormone (GnRH) on the synthesis and release of pituitary gonadotropins. In the present study, we have expressed the rat GnRH receptor (GnRH-R) in insect cells, by infection with a recombinant baculovirus. Under the conditions used, insect cells expressed, 48 h post-infection, a maximum of 7800 +/- 650 receptors/cell which bound GnRH agonist [D-Trp6]GnRH with a Kd = 0.52 +/- 0.06 nM indicating characteristics similar to those of the natural receptor. No binding was observed in non-infected cells or cells infected with wild-type baculovirus. In presence of GnRH, GnRH-R expressing cells elicited a time- and dose-dependent production of inositol trisphosphate, with a maximum level reached within 30 min and an EC50 = 5 nM. These recombinant insect cells also produced cAMP in response to GnRH. However, in contrast to other heterologous systems, or rat pituitary gonadotropes wherein GnRH induced a weak and delayed elevation of cAMP, in insect cells the rise of cAMP was comparatively rapid, attaining a maximum level after 2 h, and the EC50 was 5 nM. Finally, a clear activation of adenylyl cyclase (AC) in response to GnRH was shown for the first time by measuring the conversion of [alpha-32P]ATP into labeled cAMP, using membrane preparations from GnRH-R expressing insect cells. These data demonstrate that rat GnRH-R has the potential for dual coupling to both phosphoinositidase C and AC and suggest a major influence of the host cell for this coupling and/or its expression, probably in relation with the G protein repertoire and preference. This notion could be extended to several target cells other than pituitary gonadotropes that normally express the GnRH-R in mammals, including hippocampal, Leydig, granulosa, placental and GnRH-secreting hypothalamic cells. |
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Authors:
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R Delahaye; P R Manna; A Bérault; J Berreur-Bonnenfant; P Berreur; R Counis |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Molecular and cellular endocrinology Volume: 135 ISSN: 0303-7207 ISO Abbreviation: Mol. Cell. Endocrinol. Publication Date: 1997 Dec |
Date Detail:
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Created Date: 1998-04-08 Completed Date: 1998-04-08 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 7500844 Medline TA: Mol Cell Endocrinol Country: IRELAND |
Other Details:
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Languages: eng Pagination: 119-27 Citation Subset: IM |
Affiliation:
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Endocrinologie Cellulaire et Moléculaire de la Reproduction, Université P. & M. Curie, URA CNRS 1449, Paris, France. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adenylate Cyclase
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metabolism* Animals Cell Line Clone Cells / cytology, metabolism Cyclic AMP / metabolism Enzyme Activation / drug effects, physiology Gene Expression / genetics, physiology Inositol 1,4,5-Trisphosphate / metabolism Insects / cytology, genetics, metabolism Protein Binding Rats Receptors, LHRH / genetics*, metabolism, physiology Recombinant Proteins / genetics, metabolism, pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Receptors, LHRH; 0/Recombinant Proteins; 60-92-4/Cyclic AMP; 85166-31-0/Inositol 1,4,5-Trisphosphate; EC 4.6.1.1/Adenylate Cyclase |
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