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Chronic high glucose and pyruvate levels differentially affect mitochondrial bioenergetics and fuel-stimulated insulin secretion from clonal INS-1 832/13 cells.

  • Isabel Göhring
  • Vladimir Sharoyko
  • Siri Malmgren
  • Lotta Andersson
  • Peter Spégel
  • David Nicholls
  • Hindrik Mulder
Publishing year: 2014
Language: English
Pages: 3786-3798
Publication/Series: Journal of Biological Chemistry
Volume: 289
Issue: 6
Document type: Journal article
Publisher: ASBMB

Abstract english

Glucotoxicity in pancreatic β-cells is a well-established pathogenetic process in Type 2 Diabetes. It has been suggested that metabolism-derived reactive oxygen species perturb the β-cell transcriptional machi-nery. Less is known about altered mitochondrial function in this condition. We used INS-1 832/13 cells cultured for 48 h in 2.8 mM glucose (low-G), 16.7 mM glucose (high-G) or 2.8 mM glucose plus 13.7 mM pyruvate (high-P) to identify metabolic perturbations. High-G cells showed decreased responsiveness, relative to low-G cells, with respect to mitochondrial membrane hyperpolarization, plasma membrane depolarization and insulin secretion, when stimulated acutely with 16.7 mM glucose or 10 mM pyruvate. In contrast, high-P cells were functionally unimpaired, eliminating chronic provision of saturating mitochondrial substrate as a cause of glucotoxicity. Although cellular insulin content was depleted in high-G cells, relative to low-G and high-P cells, cellular functions were largely recovered following a further 24 h culture in low-G medium. After 2 h at 2.8 mM glucose, high-G cells did not retain increased levels of glycolytic or TCA-cycle intermediates, but nevertheless displayed increased glycolysis, increased respiration and an increased mitochondrial proton leak relative to low-G and high-P cells. This notwithstanding, titration of low-G cells with low protonophore concen-trations, monitoring respiration and insulin secretion in parallel, showed that the perturbed insulin secretion of high-G cells could not be accounted for by increased proton leak. The present study supports the idea that glucose-induced disturbances of stimulus-secretion coupling by extra-mitochondrial metabolism upstream of pyruvate, rather than exhaustion from metabolic overload, underlie glucotoxicity in insulin-producing cells.


  • Endocrinology and Diabetes


  • Molecular Metabolism
  • Diabetes and Endocrinology
  • ISSN: 1083-351X
Peter Spegel
E-mail: peter [dot] spegel [at] chem [dot] lu [dot] se


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