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Inhibition of the malate-aspartate shuttle in mouse pancreatic islets abolishes glucagon secretion without affecting insulin secretion

Stamenkovic, Jelena LU ; Andersson, Lotta LU ; Adriaenssens, Alice E.; Bagge, Annika LU ; Sharoyko, Vladimir LU ; Gribble, Fiona; Reimann, Frank; Wollheim, Claes LU ; Mulder, Hindrik LU and Spégel, Peter LU (2015) In Biochemical Journal 468. p.49-63
Abstract
Altered secretion of insulin as well as glucagon has been implicated in the pathogenesis of Type 2 diabetes (T2D), but the mechanisms controlling glucagon secretion from alpha-cells largely remain unresolved. Therefore, we studied the regulation of glucagon secretion from alpha TC1-6 (alpha TC1 clone 6) cells and compared it with insulin release from INS-1 832/13 cells. We found that INS-1 832/13 and alpha TC1-6 cells respectively secreted insulin and glucagon concentration-dependently in response to glucose. In contrast, tight coupling of glycolytic and mitochondrial metabolism was observed only in INS-1 832/13 cells. Although glycolytic metabolism was similar in the two cell lines, TCA (tricarboxylic acid) cycle metabolism, respiration... (More)
Altered secretion of insulin as well as glucagon has been implicated in the pathogenesis of Type 2 diabetes (T2D), but the mechanisms controlling glucagon secretion from alpha-cells largely remain unresolved. Therefore, we studied the regulation of glucagon secretion from alpha TC1-6 (alpha TC1 clone 6) cells and compared it with insulin release from INS-1 832/13 cells. We found that INS-1 832/13 and alpha TC1-6 cells respectively secreted insulin and glucagon concentration-dependently in response to glucose. In contrast, tight coupling of glycolytic and mitochondrial metabolism was observed only in INS-1 832/13 cells. Although glycolytic metabolism was similar in the two cell lines, TCA (tricarboxylic acid) cycle metabolism, respiration and ATP levels were less glucose-responsive in alpha TC1-6 cells. Inhibition of the malate-aspartate shuttle, using phenyl succinate (PhS), abolished glucose-provoked ATP production and hormone secretion from alpha TC1-6 but not INS-1 832/13 cells. Blocking the malate-aspartate shuttle increased levels of glycerol 3-phosphate only in INS-1 832/13 cells. Accordingly, relative expression of constituents in the glycerol phosphate shuttle compared with malate-aspartate shuttle was lower in alpha TC1-6 cells. Our data suggest that the glycerol phosphate shuttle augments the malate-aspartate shuttle in INS-1 832/13 but not alpha TC1-6 cells. These results were confirmed in mouse islets, where PhS abrogated secretion of glucagon but not insulin. Furthermore, expression of the rate-limiting enzyme of the glycerol phosphate shuttle was higher in sorted primary beta-than in alpha-cells. Thus, suppressed glycerol phosphate shuttle activity in the alpha-cell may prevent a high rate of glycolysis and consequently glucagon secretion in response to glucose. Accordingly, pyruvate-and lactate-elicited glucagon secretion remains unaffected since their signalling is independent of mitochondrial shuttles. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
coupling factors, glucose metabolism, mitochondrial transport, islets, insulin, glucagon
in
Biochemical Journal
volume
468
pages
49 - 63
publisher
Portland Press Limited
external identifiers
  • wos:000353895700005
  • scopus:84935009831
ISSN
0264-6021
DOI
10.1042/BJ20140697
language
English
LU publication?
yes
id
be6c2aba-8b8b-4b50-aad4-a22ea306509b (old id 7425444)
date added to LUP
2015-07-03 07:07:34
date last changed
2017-10-29 04:05:29
@article{be6c2aba-8b8b-4b50-aad4-a22ea306509b,
  abstract     = {Altered secretion of insulin as well as glucagon has been implicated in the pathogenesis of Type 2 diabetes (T2D), but the mechanisms controlling glucagon secretion from alpha-cells largely remain unresolved. Therefore, we studied the regulation of glucagon secretion from alpha TC1-6 (alpha TC1 clone 6) cells and compared it with insulin release from INS-1 832/13 cells. We found that INS-1 832/13 and alpha TC1-6 cells respectively secreted insulin and glucagon concentration-dependently in response to glucose. In contrast, tight coupling of glycolytic and mitochondrial metabolism was observed only in INS-1 832/13 cells. Although glycolytic metabolism was similar in the two cell lines, TCA (tricarboxylic acid) cycle metabolism, respiration and ATP levels were less glucose-responsive in alpha TC1-6 cells. Inhibition of the malate-aspartate shuttle, using phenyl succinate (PhS), abolished glucose-provoked ATP production and hormone secretion from alpha TC1-6 but not INS-1 832/13 cells. Blocking the malate-aspartate shuttle increased levels of glycerol 3-phosphate only in INS-1 832/13 cells. Accordingly, relative expression of constituents in the glycerol phosphate shuttle compared with malate-aspartate shuttle was lower in alpha TC1-6 cells. Our data suggest that the glycerol phosphate shuttle augments the malate-aspartate shuttle in INS-1 832/13 but not alpha TC1-6 cells. These results were confirmed in mouse islets, where PhS abrogated secretion of glucagon but not insulin. Furthermore, expression of the rate-limiting enzyme of the glycerol phosphate shuttle was higher in sorted primary beta-than in alpha-cells. Thus, suppressed glycerol phosphate shuttle activity in the alpha-cell may prevent a high rate of glycolysis and consequently glucagon secretion in response to glucose. Accordingly, pyruvate-and lactate-elicited glucagon secretion remains unaffected since their signalling is independent of mitochondrial shuttles.},
  author       = {Stamenkovic, Jelena and Andersson, Lotta and Adriaenssens, Alice E. and Bagge, Annika and Sharoyko, Vladimir and Gribble, Fiona and Reimann, Frank and Wollheim, Claes and Mulder, Hindrik and Spégel, Peter},
  issn         = {0264-6021},
  keyword      = {coupling factors,glucose metabolism,mitochondrial transport,islets,insulin,glucagon},
  language     = {eng},
  pages        = {49--63},
  publisher    = {Portland Press Limited},
  series       = {Biochemical Journal},
  title        = {Inhibition of the malate-aspartate shuttle in mouse pancreatic islets abolishes glucagon secretion without affecting insulin secretion},
  url          = {http://dx.doi.org/10.1042/BJ20140697},
  volume       = {468},
  year         = {2015},
}