13C NMR isotopomer analysis of anaplerotic pathways in INS-1 cells

Gary W. Cline, Rebecca L. LePine, Klearchos K. Papas, Richard G. Kibbey, Gerald I. Shulman

Research output: Contribution to journalArticle

99 Scopus citations

Abstract

Anaplerotic flux into the Kreb's cycle is crucial for glucose-stimulated insulin secretion from pancreatic β-cells. However, the regulation of flux through various anaplerotic pathways in response to combinations of physiologically relevant substrates and its impact on glucose-stimulated insulin secretion is unclear. Because different pathways of anaplerosis generate distinct products, they may differentially modulate the insulin secretory response. To examine this question, we applied 13C-isotopomer analysis to quantify flux through three anaplerotic pathways: 1) pyruvate carboxylase of pyruvate derived from glycolytic sources; 2) pyruvate carboxylase of pyruvate derived from nonglycolytic sources; and 3) glutamate dehydrogenase (GDH). At substimulatory glucose, anaplerotic flux rate in the clonal INS-1 832/13 cells was ∼40% of Kreb's cycle flux, with similar contributions from each pathway. Increasing glucose to 15 mM stimulated insulin secretion ∼4-fold, and was associated with a ∼4-fold increase in anaplerotic flux that could mostly be attributed to an increase in PC flux. In contrast, the addition of glutamine to the perfusion media stimulated GDH flux ∼6-fold at both glucose concentrations without affecting insulin secretion rates. In conclusion, these data support the hypothesis that a signal generated by anaplerosis from, increased pyruvate carboxylase flux is essential for glucose-stimulated insulin secretion in β-cells and that anaplerosis through GDH does not play a major role in this process.

Original languageEnglish (US)
Pages (from-to)44370-44375
Number of pages6
JournalJournal of Biological Chemistry
Volume279
Issue number43
DOIs
StatePublished - Oct 22 2004
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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