title: NADPH oxidase activation by hyperglycaemia in cardiomyocytes is independent of glucose metabolism but requires SGLT1.
abstract: OBJECTIVE
  Exposure to high glucose (HG) stimulates reactive oxygen species (ROS) production by NADPH oxidase in cardiomyocytes, but the underlying mechanism remains elusive. In this study, we have dissected the link between glucose transport and metabolism and NADPH oxidase activation under hyperglycaemic conditions.
  
  
  RESULTS
  Primary cultures of adult rat cardiomyocytes were exposed to HG concentration (HG, 21 mM) and compared with the normal glucose level (LG, 5 mM). HG exposure activated Rac1GTP and induced p47phox translocation to the plasma membrane, resulting in NADPH oxidase (NOX2) activation, increased ROS production, insulin resistance, and eventually cell death. Comparison of the level of O-linked N-acetylglucosamine (O-GlcNAc) residues in LG- and HG-treated cells did not reveal any significant difference. Inhibition of the pentose phosphate pathway (PPP) by 6-aminonicotinamide counteracted ROS production in response to HG but did not prevent Rac-1 upregulation and p47phox translocation leading to NOX2 activation. Modulation of glucose uptake barely affected oxidative stress and toxicity induced by HG. More interestingly, non-metabolizable glucose analogues (i.e. 3-O-methyl-D-glucopyranoside and α-methyl-D-glucopyranoside) reproduced the toxic effect of HG. Inhibition of the sodium/glucose cotransporter SGLT1 by phlorizin counteracted HG-induced NOX2 activation and ROS production.
  
  
  CONCLUSIONS
  Increased glucose metabolism by itself does not trigger NADPH oxidase activation, although PPP is required to provide NOX2 with NADPH and to produce ROS. NOX2 activation results from glucose transport through SGLT1, suggesting that an extracellular metabolic signal transduces into an intracellular ionic signal.
authors.affiliation: Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, 10, Avenue Hippocrate, 1200 Brussels,  Belgium.
authors.forename: Magali
authors.initials: M
authors.lastname: Balteau
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tajeddine
authors.forename: Carole
authors.initials: C
authors.lastname: de Meester
authors.forename: Audrey
authors.initials: A
authors.lastname: Ginion
authors.forename: Christine
authors.initials: C
authors.lastname: Des Rosiers
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Brady
authors.forename: Caroline
authors.initials: C
authors.lastname: Sommereyns
authors.forename: Sandrine
authors.initials: S
authors.lastname: Horman
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Vanoverschelde
authors.forename: Philippe
authors.initials: P
authors.lastname: Gailly
authors.forename: Louis
authors.initials: L
authors.lastname: Hue
authors.forename: Luc
authors.initials: L
authors.lastname: Bertrand
authors.forename: Christophe
authors.initials: C
authors.lastname: Beauloye
mesh_terms: D015120:6-Aminonicotinamide / Q000494:pharmacology; D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005947:Glucose / Q000031:analogs & derivatives / Q000378:metabolism*; D006031:Glycosylation; D006943:Hyperglycemia / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D007333:Insulin Resistance; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D010695:Phlorhizin / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D051269:Sodium-Glucose Transporter 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; C495676:Slc5a1 protein, rat; D051269:Sodium-Glucose Transporter 1; D015120:6-Aminonicotinamide; D010695:Phlorhizin; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein; D005947:Glucose; D000117:Acetylglucosamine