title: Inability to maintain GSH pool in G6PD-deficient red cells causes futile AMPK activation and irreversible metabolic disturbance.
abstract: OBJECTIVE
  Glucose 6-phosphate dehydrogenase (G6PD) is essential for maintenance of nicotinamide dinucleotide hydrogen phosphate (NADPH) levels and redox homeostasis. A number of drugs, such as antimalarial drugs, act to induce reactive oxygen species and hemolytic crisis in G6PD-deficient patients. We used diamide (DIA) to mimic drug-induced oxidative stress and studied how these drugs affect cellular metabolism using a metabolomic approach.
  
  
  RESULTS
  There are a few differences in metabolome between red blood cells (RBCs) from normal and G6PD-deficient individuals. DIA causes modest changes in normal RBC metabolism. In contrast, there are significant changes in various biochemical pathways, namely glutathione (GSH) metabolism, purine metabolism, and glycolysis, in G6PD-deficient cells. GSH depletion is concomitant with a shift in energy metabolism. Adenosine monophosphate (AMP) and adenosine diphosphate (ADP) accumulation activates AMP protein kinase (AMPK) and increases entry of glucose into glycolysis. However, inhibition of pyruvate kinase (PK) reduces the efficacy of energy production. Metabolic changes and protein oxidation occurs to a greater extent in G6PD-deficient RBCs than in normal cells, leading to severe irreversible loss of deformability of the former.
  
  
  CONCLUSIONS
  Normal and G6PD-deficient RBCs differ in their responses to oxidants. Normal cells have adequate NADPH regeneration for maintenance of GSH pool. In contrast, G6PD-deficient cells are unable to regenerate enough NADPH under a stressful situation, and switch to biosynthetic pathway for GSH supply. Rapid GSH exhaustion causes energy crisis and futile AMPK activation. Our findings suggest that drug-induced oxidative stress differentially affects metabolism and metabolite signaling in normal and G6PD-deficient cells. It also provides an insight into the pathophysiology of acute hemolytic anemia in G6PD-deficient patients.
authors.affiliation: 1 Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Tao-yuan, Taiwan .
authors.forename: Hsiang-Yu
authors.initials: HY
authors.lastname: Tang
authors.forename: Hung-Yao
authors.initials: HY
authors.lastname: Ho
authors.forename: Pei-Ru
authors.initials: PR
authors.lastname: Wu
authors.forename: Shih-Hsiang
authors.initials: SH
authors.lastname: Chen
authors.forename: Frans A
authors.initials: FA
authors.lastname: Kuypers
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Cheng
authors.forename: Daniel Tsun-Yee
authors.initials: DT
authors.lastname: Chiu
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000743:Anemia, Hemolytic / Q000378:metabolism; D003958:Diamide / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000378:metabolism* / Q000473:pathology*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D008715:Methionine / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010427:Pentose Phosphate Pathway; D011770:Pyruvate Kinase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects*; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D013439:Sulfhydryl Reagents; D003958:Diamide; D009249:NADP; D000255:Adenosine Triphosphate; D008715:Methionine; D011770:Pyruvate Kinase; D055372:AMP-Activated Protein Kinases; D005978:Glutathione