| Elimination of KATP channels in mouse islets results in elevated [U-13C]glucose metabolism, glutaminolysis, and pyruvate cycling but a decreased gamma-aminobutyric acid shunt. | |
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MedLine Citation:
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PMID: 18445600 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Pancreatic beta cells are hyper-responsive to amino acids but have decreased glucose sensitivity after deletion of the sulfonylurea receptor 1 (SUR1) both in man and mouse. It was hypothesized that these defects are the consequence of impaired integration of amino acid, glucose, and energy metabolism in beta cells. We used gas chromatography-mass spectrometry methodology to study intermediary metabolism of SUR1 knock-out (SUR1(-/-)) and control mouse islets with d-[U-(13)C]glucose as substrate and related the results to insulin secretion. The levels and isotope labeling of alanine, aspartate, glutamate, glutamine, and gamma-aminobutyric acid (GABA) served as indicators of intermediary metabolism. We found that the GABA shunt of SUR1(-/-) islets is blocked by about 75% and showed that this defect is due to decreased glutamate decarboxylase synthesis, probably caused by elevated free intracellular calcium. Glutaminolysis stimulated by the leucine analogue d,l-beta-2-amino-2-norbornane-carboxylic acid was, however, enhanced in SUR1(-/-) and glyburide-treated SUR1(+/+) islets. Glucose oxidation and pyruvate cycling was increased in SUR1(-/-) islets at low glucose but was the same as in controls at high glucose. Malic enzyme isoforms 1, 2, and 3, involved in pyruvate cycling, were all expressed in islets. High glucose lowered aspartate and stimulated glutamine synthesis similarly in controls and SUR1(-/-) islets. The data suggest that the interruption of the GABA shunt and the lack of glucose regulation of pyruvate cycling may cause the glucose insensitivity of the SUR1(-/-) islets but that enhanced basal pyruvate cycling, lowered GABA shunt flux, and enhanced glutaminolytic capacity may sensitize the beta cells to amino acid stimulation. |
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Authors:
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Changhong Li; Itzhak Nissim; Pan Chen; Carol Buettger; Habiba Najafi; Yevgeny Daikhin; Ilana Nissim; Heather W Collins; Marc Yudkoff; Charles A Stanley; Franz M Matschinsky |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2008-04-29 |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 283 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 2008 Jun |
Date Detail:
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Created Date: 2008-06-16 Completed Date: 2008-07-25 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: United States |
Other Details:
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Languages: eng Pagination: 17238-49 Citation Subset: IM |
Affiliation:
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Division of Endocrinology, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Triphosphate
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chemistry* Amino Acids / chemistry Animals Gas Chromatography-Mass Spectrometry / methods Genotype Glucose / metabolism* Glutamate Decarboxylase / metabolism Glutamine / chemistry* Mice Mice, Transgenic Models, Biological Oxygen / metabolism Potassium / chemistry* Pyruvates / chemistry* gamma-Aminobutyric Acid / metabolism* |
| Grant Support | |
ID/Acronym/Agency:
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DK 53012/DK/NIDDK NIH HHS; DK 53761/DK/NIDDK NIH HHS; DK 56268/DK/NIDDK NIH HHS; DK22122/DK/NIDDK NIH HHS; HD 26979/HD/NICHD NIH HHS; NS 37915/NS/NINDS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Amino Acids; 0/Pyruvates; 50-99-7/Glucose; 56-12-2/gamma-Aminobutyric Acid; 56-65-5/Adenosine Triphosphate; 56-85-9/Glutamine; 7440-09-7/Potassium; 7782-44-7/Oxygen; EC 4.1.1.15/Glutamate Decarboxylase |
| Comments/Corrections | |
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