title: Substrate preferences and glucose uptake in glibenclamide-resistant Leishmania parasites.
abstract: Several drug-resistant mammalian cell types exhibit increased glycolytic rates, preferential synthesis of ATP through oxidative phosphorylation, and altered glucose transport. Herein we analyzed the influence of parasite growth phase on energy substrate uptake and use in a Leishmania strain [NR(Gr)] selected for resistance against glibenclamide. Glibenclamide is an ABC-transporter blocker which modulates the function of glucose transporters in some mammalian cells. Our results demonstrate for the first time that compared to glibenclamide-sensitive Leishmania, exponential phase glibenclamide-resistant parasites exhibit decreased use of glucose as energy substrate, decreased glucose uptake and decreased glucose transporter expression. However, compared to glibenclamide-sensitive cells, stationary phase resistant parasites display an increased use of amino acids as energy substrate and an increased activity of the enzymes hexokinase, phosphoglucose isomerase, and especially NAD(+)-linked glutamate dehydrogenase. These results suggest that drug resistance in Leishmania involves a metabolic adaptation that promotes a stage dependent modulation of energy substrate uptake and use as a physiological response to the challenge imposed by drug pressure.
authors.affiliation: Laboratorio de Fisiología Molecular, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela.
authors.forename: Nestor Luis
authors.initials: NL
authors.lastname: Uzcategui
authors.forename: Katherine
authors.initials: K
authors.lastname: Figarella
authors.forename: Natacha
authors.initials: N
authors.lastname: Camacho
authors.forename: Alicia
authors.initials: A
authors.lastname: Ponte-Sucre
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D003571:Cytochalasin B / Q000494:pharmacology; D004351:Drug Resistance; D005947:Glucose / Q000378:metabolism*; D005956:Glucose-6-Phosphate Isomerase / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D005905:Glyburide / Q000494:pharmacology*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007891:Leishmania / Q000187:drug effects* / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D009004:Monosaccharide Transport Proteins; D003571:Cytochalasin B; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005969:Glutamate Dehydrogenase; D000410:Alanine Transaminase; D006593:Hexokinase; D005956:Glucose-6-Phosphate Isomerase; D005947:Glucose; D005905:Glyburide