Insulin stimulates glucose metabolism via the pentose phosphate pathway in Drosophila Kc cells

FEBS Lett. 2003 Dec 4;555(2):307-10. doi: 10.1016/s0014-5793(03)01261-4.

Abstract

Drosophila melanogaster has become a prominent and convenient model for analysis of insulin action. However, to date very little is known regarding the effect of insulin on glucose uptake and metabolism in Drosophila. Here we show that, in contrast to effects seen in mammals, insulin did not alter [(3)H]2-deoxyglucose uptake and in fact decreased glycogen synthesis ( approximately 30%) in embryonic Drosophila Kc cells. Insulin significantly increased ( approximately 1.5-fold) the production of (14)CO(2) from D-[1-(14)C]glucose while the production of (14)CO(2) from D-[6-(14)C]glucose was not altered. Thus, insulin-stimulated glucose oxidation did not occur via increasing Krebs cycle activity but rather by stimulating the pentose phosphate pathway. Indeed, inhibition of the oxidative pentose phosphate pathway by 6-aminonicotinamide abolished the effect of insulin on (14)CO(2) from D-[U-(14)C]glucose. A corresponding increase in lactate production but no change in incorporation of D-[U-(14)C]glucose into total lipids was observed in response to insulin. Glucose metabolism via the pentose phosphate pathway may provide an important source of 5'-phosphate for DNA synthesis and cell replication. This novel observation correlates well with the fact that control of growth and development is the major role of insulin-like peptides in Drosophila. Thus, although intracellular signaling is well conserved, the metabolic effects of insulin are dramatically different between Drosophila and mammals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Aminonicotinamide / pharmacology
  • Animals
  • Carbon Dioxide / analysis
  • Carbon Dioxide / metabolism
  • Carbon Radioisotopes
  • Cell Line
  • Deoxyglucose / analogs & derivatives
  • Deoxyglucose / metabolism
  • Drosophila melanogaster / metabolism*
  • Glucose / analogs & derivatives
  • Glucose / metabolism*
  • Glycogen / biosynthesis
  • Insulin / pharmacology*
  • Lactic Acid / analysis
  • Lactic Acid / biosynthesis
  • Pentose Phosphate Pathway / drug effects
  • Pentose Phosphate Pathway / physiology*
  • Tritium

Substances

  • Carbon Radioisotopes
  • Insulin
  • Tritium
  • Carbon Dioxide
  • 6-Aminonicotinamide
  • Lactic Acid
  • Glycogen
  • Deoxyglucose
  • Glucose