TY - JOUR
T1 - Role of AMP-activated protein kinase in the regulation by glucose of islet beta cell gene expression
AU - Da Silva Xavier, Gabriela
AU - Leclerc, Isabelle
AU - Salt, Ian P.
AU - Doiron, Bruno
AU - Hardie, D. Grahame
AU - Kahn, Axel
AU - Rutter, Guy A.
PY - 2000/4/11
Y1 - 2000/4/11
N2 - Elevated glucose concentrations stimulate the transcription of the pre- proinsulin (PPI), L-type pyruvate kinase (L-PK), and other genes in islet beta cells. In liver cells, pharmacological activation by 5-amino-4- imidazolecarboxamide riboside (AlCAR) of AMP-activated protein kinase (AMPK), the mammalian homologue of the yeast SNF1 kinase complex, inhibits the effects of glucose, suggesting a key signaling role for this kinase. Here, we demonstrate that AMPK activity is inhibited by elevated glucose concentrations in MlN6 beta cells and that activation of the enzyme with AlCAR prevents the activation of the L-PK gene by elevated glucose. Furthermore, microinjection of antibodies to the α2(catalytic) or β2- subunits of AMPK complex, but not to the α1-subunit or extracellular stimulus-regulated kinase, mimics the effects of elevated glucose on the L-PK and PPI promoter activities as assessed by single-cell imaging of promoter luciferase constructs. In each case, injection of antibodies into the nucleus and cytosol, but not the nucleus alone, was necessary, indicating the importance of either a cytosolic phosphorylation event or the subcellular localization of the α2-subunits. Incubation with AlCAR diminished, but did not abolish, the effect of glucose on PPI transcription. These data suggest that glucose-induced changes in AMPK activity are necessary and sufficient for the regulation of the L-PK gene by the sugar and also play an important role in the regulation of the PPI promoter.
AB - Elevated glucose concentrations stimulate the transcription of the pre- proinsulin (PPI), L-type pyruvate kinase (L-PK), and other genes in islet beta cells. In liver cells, pharmacological activation by 5-amino-4- imidazolecarboxamide riboside (AlCAR) of AMP-activated protein kinase (AMPK), the mammalian homologue of the yeast SNF1 kinase complex, inhibits the effects of glucose, suggesting a key signaling role for this kinase. Here, we demonstrate that AMPK activity is inhibited by elevated glucose concentrations in MlN6 beta cells and that activation of the enzyme with AlCAR prevents the activation of the L-PK gene by elevated glucose. Furthermore, microinjection of antibodies to the α2(catalytic) or β2- subunits of AMPK complex, but not to the α1-subunit or extracellular stimulus-regulated kinase, mimics the effects of elevated glucose on the L-PK and PPI promoter activities as assessed by single-cell imaging of promoter luciferase constructs. In each case, injection of antibodies into the nucleus and cytosol, but not the nucleus alone, was necessary, indicating the importance of either a cytosolic phosphorylation event or the subcellular localization of the α2-subunits. Incubation with AlCAR diminished, but did not abolish, the effect of glucose on PPI transcription. These data suggest that glucose-induced changes in AMPK activity are necessary and sufficient for the regulation of the L-PK gene by the sugar and also play an important role in the regulation of the PPI promoter.
KW - Insulin
KW - L-type pyruvate kinase
KW - Promoter
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U2 - 10.1073/pnas.97.8.4023
DO - 10.1073/pnas.97.8.4023
M3 - Article
C2 - 10760274
AN - SCOPUS:0034636006
SN - 0027-8424
VL - 97
SP - 4023
EP - 4028
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 8
ER -