title: Activation of general control nonderepressible 2 kinase protects human glomerular endothelial cells from harmful high-glucose-induced molecular pathways.
abstract: OBJECTIVE
  Considering the referred beneficial effects of protein restriction on diabetic nephropathy (DN) and the role of renal endothelium in its pathogenesis, we evaluated the effect of general control nonderepressible 2 (GCN2) kinase activation, a sensor of amino acid deprivation, on known detrimental molecular pathways in primary human glomerular endothelial cells (GEnC).
  
  
  METHODS
  GEnC were cultured under normal or high-glucose conditions in the presence or not of the GCN2 kinase activator, tryptophanol. Glucose transporter 1 (GLUT1) expression was assessed by western blotting and reactive oxygen species (ROS) using a fluorogenic probe. Activities of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and protein kinase C (PKC) were assessed by commercial activity assays, sorbitol colorimetrically, methylglyoxal by ELISA and O-linked β-N-acetyl glucosamine (O-GlcNAc)-modified proteins by western blotting.
  
  
  RESULTS
  High glucose induced GLUT1 expression, increased ROS and inhibited GAPDH. Also it increased the polyol pathway product sorbitol, PKC activity, the level of the O-GlcNAc-modified proteins that produced by the hexosamine pathway and the advanced glycation endproducts' precursor methylglyoxal. Co-treatment of GEnC with tryptophanol restored the above high-glucose-induced alterations.
  
  
  CONCLUSIONS
  Activation of GCN2 kinase protects GEnC from high-glucose-induced harmful molecular pathways. By inhibiting concurrently many pathways involved in DN pathogenesis, GCN2 kinase may serve as a pharmaceutical target for the treatment of DN.
authors.affiliation: Department of Nephrology, Medical School, University of Thessaly, Neo Ktirio, Mezourlo Hill, 41110, Larissa, Greece. teleftheriadis@yahoo.com.
authors.forename: Theodoros
authors.identifier: http://orcid.org/0000-0001-9302-1633
authors.initials: T
authors.lastname: Eleftheriadis
authors.affiliation: Department of Nephrology, Medical School, University of Thessaly, Neo Ktirio, Mezourlo Hill, 41110, Larissa, Greece.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Tsogka
authors.affiliation: Department of Nephrology, Medical School, University of Thessaly, Neo Ktirio, Mezourlo Hill, 41110, Larissa, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Pissas
authors.affiliation: Department of Nephrology, Medical School, University of Thessaly, Neo Ktirio, Mezourlo Hill, 41110, Larissa, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Antoniadi
authors.affiliation: Department of Nephrology, Medical School, University of Thessaly, Neo Ktirio, Mezourlo Hill, 41110, Larissa, Greece.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Liakopoulos
authors.affiliation: Department of Nephrology, Medical School, University of Thessaly, Neo Ktirio, Mezourlo Hill, 41110, Larissa, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Stefanidis
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D002478:Cells, Cultured; D003928:Diabetic Nephropathies / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D051272:Glucose Transporter Type 1 / Q000378:metabolism*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D006801:Humans; D010446:Peptide Fragments / Q000378:metabolism*; D065840:Protective Factors; D011493:Protein Kinase C / Q000378:metabolism*; D014364:Tryptophan / Q000031:analogs & derivatives / Q000494:pharmacology; D019459:Urothelium / Q000187:drug effects / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D051272:Glucose Transporter Type 1; D010446:Peptide Fragments; C068142:glyceraldehyde 3-phosphate dehydrogenase (304-313); C069544:tryptophanol; D014364:Tryptophan; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D011493:Protein Kinase C
keywords: AGEs; Aldose reductase; Diabetic nephropathy; Endothelium; GCN2 kinase; Hexosamine; PKC; ROS