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Pyruvate dehydrogenase kinase 1 controls mitochondrial metabolism and insulin secretion in INS-1 832/13 clonal beta-cells

Krus, Ulrika LU ; Kotova, Olga LU ; Spégel, Peter LU ; Hallgard, Elna; Sharoyko, Vladimir LU ; Vedin, Anna LU ; Moritz, Thomas; Sugden, Mary C.; Köck, Thomas LU and Mulder, Hindrik LU (2010) In Biochemical Journal 429. p.205-213
Abstract
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 beta-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... (More)
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 beta-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 alpha-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 beta-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 beta-cells and that PDH kinase 1 and PDH are important for efficient metabolic coupling. Maintaining low PDH kinase I expression/activity, keeping PDH in a dephosphorylated and active state, may be important for beta-cells to achieve the metabolic flux rates necessary for maximal GSIS. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
pyruvate dehydrogenase kinase 1, oxygen, mitochondria, insulin secretion, beta-cell, electron transport, stimulus-secretion coupling
in
Biochemical Journal
volume
429
pages
205 - 213
publisher
Portland Press Limited
external identifiers
  • wos:000279418500020
  • scopus:77954524639
ISSN
0264-6021
DOI
10.1042/BJ20100142
language
English
LU publication?
yes
id
2dc3b368-04b2-4131-b6b1-02888c906fff (old id 1629344)
date added to LUP
2010-07-22 10:57:24
date last changed
2018-05-29 11:05:05
@article{2dc3b368-04b2-4131-b6b1-02888c906fff,
  abstract     = {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 beta-cells. Knockdown of PDH kinase 1 with siRNA (small interfering RNA) reduced its mRNA (&gt;80 %) and protein level (&gt;40 %) after 72 h. PDH activity, glucose-stimulated cellular oxygen consumption and pyruvate-stimulated mitochondrial oxygen consumption increased 1.7- (P &lt; 0.05), 1.6- (P &lt; 0.05) and 1.6-fold (P &lt; 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 alpha-ketoglutarate. These metabolic alterations were associated with exaggerated GSIS (5-fold compared with 3.1-fold in control cells; P &lt; 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 beta-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 beta-cells and that PDH kinase 1 and PDH are important for efficient metabolic coupling. Maintaining low PDH kinase I expression/activity, keeping PDH in a dephosphorylated and active state, may be important for beta-cells to achieve the metabolic flux rates necessary for maximal GSIS.},
  author       = {Krus, Ulrika and Kotova, Olga and Spégel, Peter and Hallgard, Elna and Sharoyko, Vladimir and Vedin, Anna and Moritz, Thomas and Sugden, Mary C. and Köck, Thomas and Mulder, Hindrik},
  issn         = {0264-6021},
  keyword      = {pyruvate dehydrogenase kinase 1,oxygen,mitochondria,insulin secretion,beta-cell,electron transport,stimulus-secretion coupling},
  language     = {eng},
  pages        = {205--213},
  publisher    = {Portland Press Limited},
  series       = {Biochemical Journal},
  title        = {Pyruvate dehydrogenase kinase 1 controls mitochondrial metabolism and insulin secretion in INS-1 832/13 clonal beta-cells},
  url          = {http://dx.doi.org/10.1042/BJ20100142},
  volume       = {429},
  year         = {2010},
}