Tight coupling between cytosolic and mitochondrial metabolism is key for GSIS (glucose-stimulated insulin secretion). In the present study we examined the regulatory contribution of PDH (pyruvate dehydrogenase) kinase 1, a negative regulator of PDH, to metabolic coupling in 832/13 clonal β-cells. Knockdown of PDH kinase 1 with siRNA (small interfering RNA) reduced its mRNA (>80%) and protein level (>40%) after 72 h. PDH activity, glucose-stimulated cellular oxygen consumption and pyruvate-stimulated mitochondrial oxygen consumption increased 1.7- (P<0.05), 1.6- (P<0.05) and 1.6-fold (P<0.05) respectively. Gas chromatography/MS revealed an altered metabolite profile upon silencing of PDH kinase 1, determined by increased levels of the tricarboxylic acid cycle intermediates malate, fumarate and α-ketoglutarate. These metabolic alterations were associated with exaggerated GSIS (5-fold compared with 3.1-fold in control cells; P<0.01). Insulin secretion, provoked by leucine and dimethylsuccinate, which feed into the tricarboxylic acid cycle bypassing PDH, was unaffected. The oxygen consumption and metabolic data strongly suggest that knockdown of PDH kinase 1 in β-cells permits increased metabolic flux of glucose-derived carbons into the tricarboxylic acid cycle via PDH. Enhanced insulin secretion is probably caused by increased generation of tricarboxylic acid cycle-derived reducing equivalents for mitochondrial electron transport to generate ATP and/or stimulatory metabolic intermediates. On the basis of these findings, we suggest that PDH kinase 1 is an important regulator of PDH in clonal β-cells and that PDH kinase 1 and PDH are important for efficient metabolic coupling. Maintaining low PDH kinase 1 expression/activity, keeping PDH in a dephosphorylated and active state, may be important for β-cells to achieve the metabolic flux rates necessary for maximal GSIS.
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Research Article|
June 14 2010
Pyruvate dehydrogenase kinase 1 controls mitochondrial metabolism and insulin secretion in INS-1 832/13 clonal β-cells Available to Purchase
Ulrika Krus;
Ulrika Krus
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Olga Kotova;
Olga Kotova
1
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
1To whom correspondence should be addressed (email [email protected]).
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Peter Spégel;
Peter Spégel
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Elna Hallgard;
Elna Hallgard
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Vladimir V. Sharoyko;
Vladimir V. Sharoyko
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Anna Vedin;
Anna Vedin
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Thomas Moritz;
Thomas Moritz
†Umeå Plant Science Center, Swedish University of Agricultural Sciences, 90187 Umeå, Sweden
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Mary C. Sugden;
Mary C. Sugden
‡Queen Mary University of London, Centre for Diabetes and Metabolic Medicine, Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, 4 Newark Street, London E1 2AT, U.K.
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Thomas Koeck;
Thomas Koeck
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Hindrik Mulder
Hindrik Mulder
*Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö University Hospital, 20502 Malmö, Sweden
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Publisher: Portland Press Ltd
Received:
January 25 2010
Revision Received:
March 29 2010
Accepted:
April 23 2010
Accepted Manuscript online:
April 23 2010
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2010 Biochemical Society
2010
Biochem J (2010) 429 (1): 205–213.
Article history
Received:
January 25 2010
Revision Received:
March 29 2010
Accepted:
April 23 2010
Accepted Manuscript online:
April 23 2010
Citation
Ulrika Krus, Olga Kotova, Peter Spégel, Elna Hallgard, Vladimir V. Sharoyko, Anna Vedin, Thomas Moritz, Mary C. Sugden, Thomas Koeck, Hindrik Mulder; Pyruvate dehydrogenase kinase 1 controls mitochondrial metabolism and insulin secretion in INS-1 832/13 clonal β-cells. Biochem J 1 July 2010; 429 (1): 205–213. doi: https://doi.org/10.1042/BJ20100142
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