title: Gene expression profiling and molecular characterization of antimony resistance in Leishmania amazonensis.
abstract: BACKGROUND
  Drug resistance is a major problem in leishmaniasis chemotherapy. RNA expression profiling using DNA microarrays is a suitable approach to study simultaneous events leading to a drug-resistance phenotype. Genomic analysis has been performed primarily with Old World Leishmania species and here we investigate molecular alterations in antimony resistance in the New World species L. amazonensis.
  
  
  RESULTS
  We selected populations of L. amazonensis promastigotes for resistance to antimony by step-wise drug pressure. Gene expression of highly resistant mutants was studied using DNA microarrays. RNA expression profiling of antimony-resistant L. amazonensis revealed the overexpression of genes involved in drug resistance including the ABC transporter MRPA and several genes related to thiol metabolism. The MRPA overexpression was validated by quantitative real-time RT-PCR and further analysis revealed that this increased expression was correlated to gene amplification as part of extrachromosomal linear amplicons in some mutants and as part of supernumerary chromosomes in other mutants. The expression of several other genes encoding hypothetical proteins but also nucleobase and glucose transporter encoding genes were found to be modulated.
  
  
  CONCLUSIONS
  Mechanisms classically found in Old World antimony resistant Leishmania were also highlighted in New World antimony-resistant L. amazonensis. These studies were useful to the identification of resistance molecular markers.
authors.affiliation: Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil.
authors.forename: Rubens L
authors.initials: RL
authors.lastname: do Monte-Neto
authors.forename: Adriano C
authors.initials: AC
authors.lastname: Coelho
authors.forename: Frédéric
authors.initials: F
authors.lastname: Raymond
authors.forename: Danielle
authors.initials: D
authors.lastname: Légaré
authors.forename: Jacques
authors.initials: J
authors.lastname: Corbeil
authors.forename: Maria N
authors.initials: MN
authors.lastname: Melo
authors.forename: Frédéric
authors.initials: F
authors.lastname: Frézard
authors.forename: Marc
authors.initials: M
authors.lastname: Ouellette
mesh_terms: D000818:Animals; D000965:Antimony / Q000633:toxicity*; D000981:Antiprotozoal Agents / Q000633:toxicity*; D004351:Drug Resistance; D020869:Gene Expression Profiling; D006801:Humans; D007894:Leishmania mexicana / Q000187:drug effects* / Q000235:genetics*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D046228:Microarray Analysis
chemical_list: D000981:Antiprotozoal Agents; D000965:Antimony