| Molecular and functional studies of inhibitory G protein in RINm5F cells. | |
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MedLine Citation:
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PMID: 7526047 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Inhibitory G proteins (Gi) play an important role in cell proliferation. In order to characterize Gi proteins in RINm5F (RIN) cells, we first established RIN cells in cell culture. Immunoblot analysis was performed on extracted G proteins using Western blot techniques and a Gi-specific antibody. We identified three prominent bands consistent with three distinct inhibitory alpha subunits of membrane-bound G protein (Gi) in RIN cells. In contrast, we identified only one prominent distinct inhibitory alpha subunit of G protein in an equal quantity of membrane-protein in our control (normal rat pancreas). In several cell types, Gi is known to mediate the inhibitory action of somatostatin on intracellular cyclic AMP (cAMP) accumulation. Therefore, we studied the action of the long-acting analogue of somatostatin, octreotide (SMS), on basal and 3-isobutyl-1-methylxanthine-stimulated cAMP accumulation in RIN cells. SMS did not inhibit cAMP accumulation or tritiated thymidine incorporation into DNA (TTID) in RIN cells. However, when treatment with SMS is supplemented with the nonhydrolyzable analogue of guanine nucleotide, Gpp(NH)p (Gpp), which is known to dissociate G proteins into its constitutive subunits, then SMS+Gpp induced an inhibitory action and significantly reduced cAMP accumulation and TTID. These data are consistent with the concept of qualitatively and functionally altered inhibitory G protein expression in the insulin-producing, islet cell (RINm5F) rat insulinoma tumor cell line. Further study of human tumors will lead to new insights into the clinical implications of G protein-mediated signal transduction in insulinoma. |
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Authors:
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M K McLeod; P C Kothary; C M Farrell |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of surgical research Volume: 57 ISSN: 0022-4804 ISO Abbreviation: J. Surg. Res. Publication Date: 1994 Nov |
Date Detail:
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Created Date: 1994-12-08 Completed Date: 1994-12-08 Revised Date: 2003-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0376340 Medline TA: J Surg Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 619-24 Citation Subset: IM |
Affiliation:
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Department of Surgery, University of Michigan Medical Center, Ann Arbor 48109. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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1-Methyl-3-isobutylxanthine
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pharmacology Animals Cyclic AMP / metabolism DNA, Neoplasm / biosynthesis Drug Combinations GTP-Binding Proteins / metabolism* Guanylyl Imidodiphosphate / pharmacology Insulinoma / drug therapy, metabolism* Octreotide / pharmacology Pancreas / metabolism Pancreatic Neoplasms / drug therapy, metabolism* Rats Tumor Cells, Cultured |
| Chemical | |
Reg. No./Substance:
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0/DNA, Neoplasm; 0/Drug Combinations; 28822-58-4/1-Methyl-3-isobutylxanthine; 34273-04-6/Guanylyl Imidodiphosphate; 60-92-4/Cyclic AMP; 83150-76-9/Octreotide; EC 3.6.1.-/GTP-Binding Proteins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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