%0 Journal Article
%T Glucose-Induced O2 Consumption Activates Hypoxia Inducible Factors 1 and 2 in Rat Insulin-Secreting Pancreatic Beta-Cells
%A Mohammed Bensellam
%A Bertrand Duvilli¨¦
%A Galyna Rybachuk
%A D. Ross Laybutt
%A Christophe Magnan
%A Yves Guiot
%A Jacques Pouyss¨¦gur
%A Jean-Christophe Jonas
%J PLOS ONE
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0029807
%X Background Glucose increases the expression of glycolytic enzymes and other hypoxia-response genes in pancreatic beta-cells. Here, we tested whether this effect results from the activation of Hypoxia-Inducible-factors (HIF) 1 and 2 in a hypoxia-dependent manner. Methodology/Principal Findings Isolated rat islets and insulin-secreting INS-1E cells were stimulated with nutrients at various pO2 values or treated with the HIF activator CoCl2. HIF-target gene mRNA levels and HIF subunit protein levels were measured by real-time RT-PCR, Western Blot and immunohistochemistry. The formation of pimonidazole-protein adducts was used as an indicator of hypoxia. In INS-1E and islet beta-cells, glucose concentration-dependently stimulated formation of pimonidazole-protein adducts, HIF1 and HIF2 nuclear expression and HIF-target gene mRNA levels to a lesser extent than CoCl2 or a four-fold reduction in pO2. Islets also showed signs of HIF activation in diabetic Leprdb/db but not non-diabetic Leprdb/+ mice. In vitro, these glucose effects were reproduced by nutrient secretagogues that bypass glycolysis, and were inhibited by a three-fold increase in pO2 or by inhibitors of Ca2+ influx and insulin secretion. In INS-1E cells, small interfering RNA-mediated knockdown of Hif1¦Á and Hif2¦Á, alone or in combination, indicated that the stimulation of glycolytic enzyme mRNA levels depended on both HIF isoforms while the vasodilating peptide adrenomedullin was a HIF2-specific target gene. Conclusions/Significance Glucose-induced O2 consumption creates an intracellular hypoxia that activates HIF1 and HIF2 in rat beta-cells, and this glucose effect contributes, together with the activation of other transcription factors, to the glucose stimulation of expression of some glycolytic enzymes and other hypoxia response genes.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029807