title: Gene expression modulation is associated with gene amplification, supernumerary chromosomes and chromosome loss in antimony-resistant Leishmania infantum.
abstract: Antimonials remain the first line drug against the protozoan parasite Leishmania but their efficacy is threatened by resistance. We carried out a RNA expression profiling analysis comparing an antimony-sensitive and -resistant (Sb2000.1) strain of Leishmania infantum using whole-genome 70-mer oligonucleotide microarrays. Several genes were differentially expressed between the two strains, several of which were found to be physically linked in the genome. MRPA, an ATP-binding cassette (ABC) gene known to be involved in antimony resistance, was overexpressed in the antimony-resistant mutant along with three other tandemly linked genes on chromosome 23. This four gene locus was flanked by 1.4 kb repeated sequences from which an extrachromosomal circular amplicon was generated in the resistant cells. Interestingly, gene expression modulation of entire chromosomes occurred in the antimony-resistant mutant. Southern blots analyses and comparative genomic hybridizations revealed that this was either due to the presence of supernumerary chromosomes or to the loss of one chromosome. Leishmania parasites with haploid chromosomes were viable. Changes in copy number for some of these chromosomes were confirmed in another antimony-resistant strain. Selection of a partial revertant line correlated antimomy resistance levels and the copy number of aneuploid chromosomes, suggesting a putative link between aneuploidy and drug resistance in Leishmania.
authors.affiliation: Centre de Recherche en Infectiologie et Division de Microbiologie, Université Laval, Québec, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Leprohon
authors.forename: Danielle
authors.initials: D
authors.lastname: Légaré
authors.forename: Frédéric
authors.initials: F
authors.lastname: Raymond
authors.forename: Eric
authors.initials: E
authors.lastname: Madore
authors.forename: Gary
authors.initials: G
authors.lastname: Hardiman
authors.forename: Jacques
authors.initials: J
authors.lastname: Corbeil
authors.forename: Marc
authors.initials: M
authors.lastname: Ouellette
mesh_terms: D000782:Aneuploidy; D000818:Animals; D000965:Antimony / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics; D005784:Gene Amplification; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D018314:Leishmania infantum / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D009006:Monosomy; D009154:Mutation; D014344:Trypanocidal Agents / Q000494:pharmacology*
chemical_list: D014344:Trypanocidal Agents; D000965:Antimony