title: Adenosine 5'-monophosphate-activated protein kinase and p38 mitogen-activated protein kinase participate in the stimulation of glucose uptake by dinitrophenol in adult cardiomyocytes.
abstract: During metabolic stress, such as ischemia or hypoxia, glucose becomes the principal energy source for the heart. It has been shown that increased cardiac glucose uptake during metabolic stress has a protective effect on cell survival and heart function. Despite its physiological importance, only limited data are available on the molecular mechanisms regulating glucose uptake under these conditions. We used 2,4-dinitrophenol (DNP), an uncoupler of oxidative phosphorylation, as a model to mimic hypoxia and gain insight into the signaling pathway underlying metabolic stress-induced glucose uptake in primary cultures of rat adult cardiomyocytes. The results demonstrate that 0.1 mM DNP induces 2.2- and 9-fold increases in AMP-activated protein kinase (AMPK) and p38 MAPK phosphorylation, respectively. This is associated with a 2.3-fold increase in glucose uptake in these cells. To further delineate the role of AMPK in the regulation of glucose uptake, we used two complementary approaches: pharmacological inhibition of the enzyme with adenine 9-beta-D arabinofuranoside and adenoviral infection with a dominant-negative AMPK (DN-AMPK) mutant. Our results show that overexpression of DN-AMPK completely suppressed DNP-mediated phosphorylation of acetyl coenzyme A carboxylase, a downstream target of AMPK. Inhibition of AMPK with either 9-beta-D arabinofuranoside or DN-AMPK also abolished DNP-mediated p38 MAPK phosphorylation. Importantly, AMPK inhibition only partially decreased DNP-stimulated glucose uptake in cardiomyocytes. Inhibition of p38 MAPK with the pharmacological agent PD169316 also partially reduced (70%) glucose uptake in response to DNP. In conclusion, our results indicate that p38 MAPK acts downstream of AMPK in cardiomyocytes and that activation of the AMPK/p38 MAPK signaling cascade is essential for maximal stimulation of glucose uptake in response to DNP in adult cardiomyocytes.
authors.affiliation: Montreal Diabetes Research Centre, Centre Hospitalier de l'Université de Montréal and the Department of Medicine, Université de Montréal, Montréal, Québec, Canada H2W 1T7.
authors.forename: Amélie
authors.initials: A
authors.lastname: Pelletier
authors.forename: Erik
authors.initials: E
authors.lastname: Joly
authors.forename: Marc
authors.initials: M
authors.lastname: Prentki
authors.forename: Lise
authors.initials: L
authors.lastname: Coderre
mesh_terms: D019297:2,4-Dinitrophenol / Q000494:pharmacology*; D055372:AMP-Activated Protein Kinases; D000818:Animals; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000032:analysis; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D009124:Muscle Proteins / Q000032:analysis; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D014162:Transfection; D014475:Uncoupling Agents / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009097:Multienzyme Complexes; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D014475:Uncoupling Agents; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D055372:AMP-Activated Protein Kinases; D005947:Glucose; D019297:2,4-Dinitrophenol