| Metabolism of pro-luteinizing hormone-releasing hormone in immortalized hypothalamic neurons. | |
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MedLine Citation:
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PMID: 1714837 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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An immortalized hypothalamic neuronal cell line was recently developed by genetically targeting the expression of the simian virus-40 large T-antigen in LHRH neurons. These GT1 cells were subcloned to GT1-1, GT1-3, and GT1-7 cells, and they have been shown to express the mRNA for pro-LHRH and secrete LHRH-like immunoreactive (IR) materials into the media. The purpose of our study was to biochemically and immunologically characterize the IR materials within and secreted from these cells. Both LHRH- and GnRH-associated peptide (GAP)-like IR materials were present and were secreted from these four cell lines. Up to 3% of the total cellular protein was composed of LHRH and GAP materials. When materials from the cell lysate and media were separated according to mol wt (Mr), at least three different pro-LHRH species were detected. These precursors contained both LHRH- and GAP-like IR determinants, and they eluted in the void volume and at approximately 10,000-12,000 and 8,400-8,500 Mr. A material that contained GAP-like IR eluted at approximately 6,500-6,800 Mr. This species is probably mouse GAP-(1-56) because it eluted on a reverse phase column in the approximate position of rat GAP-(1-56). Cell lysates contained a single LHRH-like IR form which coeluted on a size-exclusion column with synthetic LHRH. This material stimulated secretion of LH from anterior pituitary cells in a dose-response manner. By comparison, two different molecular forms of LHRH were detected in media at approximately 1,500 and 540 Mr. HPLC analyses revealed these peaks to be heterogeneous and to contain at least (Gln1)LHRH-(Gly11,Lys12,Arg13), (Gln1)LHRH-(Gly1,Lys12), LHRH-(Gly11), and LHRH. These experiments demonstrate that the cells contain and secrete multiple molecular forms of the pro-LHRH and that processing of the prohormone must involve 1) cleavage by an endopeptidase to give GAP-(1-56) and a C-terminally extended LHRH, 2) removal of C-terminal basic amino acids by a carboxypeptidase, 3) amidation of LHRH-(Gly11) to LHRH, and 4) cyclization of glutamine to pyroglutamate at the N-terminal of LHRH. These results provide the first evidence for intermediates in the metabolic pathway of pro-LHRH to LHRH. |
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Authors:
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W C Wetsel; P L Mellon; R I Weiner; A Negro-Vilar |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Endocrinology Volume: 129 ISSN: 0013-7227 ISO Abbreviation: Endocrinology Publication Date: 1991 Sep |
Date Detail:
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Created Date: 1991-09-20 Completed Date: 1991-09-20 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0375040 Medline TA: Endocrinology Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1584-95 Citation Subset: AIM; IM |
Affiliation:
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Reproductive Neuroendocrinology Section, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acid Sequence Animals Antigens, Polyomavirus Transforming / genetics Cell Line Clone Cells Epitopes / genetics Gene Expression Gonadotropin-Releasing Hormone / biosynthesis, genetics, isolation & purification, metabolism* Humans Hypothalamus / metabolism* Mice Molecular Sequence Data Neurons / metabolism* Protein Precursors / genetics, metabolism* RNA, Messenger / genetics, metabolism Rats Sequence Homology, Nucleic Acid Simian virus 40 / genetics, immunology Transfection |
| Grant Support | |
ID/Acronym/Agency:
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HD-08924/HD/NICHD NIH HHS; HD-20377/HD/NICHD NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Antigens, Polyomavirus Transforming; 0/Epitopes; 0/Protein Precursors; 0/RNA, Messenger; 0/progonadoliberin I; 33515-09-2/Gonadotropin-Releasing Hormone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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