Role of 5'-AMP-activated protein kinase in stimulation of glucose transport in response to inhibition of oxidative phosphorylation.
Glucose transport is stimulated in a variety of cells and tissues in response to inhibition of oxidative phosphorylation. However, the underlying mechanisms and mediating steps remain largely unknown. In the present study we first tested whether a decrease in the redox state of the cell per se and the resultant increase in generation of reactive oxygen species (ROS) lead to stimulation of glucose transport. Clone 9 cells (expressing the Glut1 isoform of facilitative glucose transporters) were exposed to azide, lactate, and ethanol for 1 h. Although all three agents stimulated glucose transport and increased cell NADH-to-NAD(+) ratio and phospho-ERK1/2, signifying increased ROS generation, the response to the stimuli was not blocked by N-acetyl-l-cysteine (an agent that counteracts ROS); moreover, the response to azide was not blocked by diamide (an intracellular sulfhydryl oxidizing agent). We then found that cell AMP-to-ATP and ADP-to-ATP ratios were increased and 5'-AMP-activated protein kinase (AMPK) was stimulated by all three agents, as evidenced by increased phosphorylation of AMPK and acetyl-CoA carboxylase. We conclude that although azide, lactate, and ethanol increase NADH-to-NAD(+) ratios and ROS production, their stimulatory effect on glucose transport is not mediated by increased ROS generation. However, all three agents increased cell AMP-to-ATP ratio and stimulated AMPK, making it likely that the latter pathway plays an important role in the glucose transport response.
Jing
Ming
M
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4951, USA.
Ismail-Beigi
Faramarz
F
D055372:AMP-Activated Protein Kinases; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D001386:Azides / Q000378:metabolism; D002460:Cell Line; D000431:Ethanol / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007004:Hypoglycemic Agents / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010085:Oxidative Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism
D001386:Azides; D007004:Hypoglycemic Agents; D007773:Lactates; D009097:Multienzyme Complexes; D017382:Reactive Oxygen Species; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D000431:Ethanol; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose