title: The role of Trypanosoma brucei MRPA in melarsoprol susceptibility.
abstract: We previously showed that over-expression of Trypanosoma brucei MRPA, a member of the multidrug resistance protein family in T. brucei, reproducibly resulted in resistance to the anti-trypanosomal drug melarsoprol in vitro. MRPA is predicted to mediate efflux of melarsoprol as a conjugate with trypanothione, a glutathione-spermidine conjugate which is the major small thiol in trypanosomes. Here, we show that depletion of MRPA by RNA interference resulted in moderate hypersensitivity to both melarsoprol and melarsen oxide. Over-expression of MRPA alone is not sufficient to cause melarsoprol resistance in vivo, although it is sufficient in vitro. This discrepancy is not an effect of drug metabolism since over-expression of MRPA alone conferred resistance to melarsoprol and its principle metabolite, melarsen oxide, in vitro. Over-expression of MRPA was not detected in four melarsoprol-resistant trypanosome isolates from sleeping sickness patients.
authors.affiliation: Universitat Heidelberg, Zentrum fur Molekulare Biologie (ZMBH), Im Neuenheimer Feld 282, D69120 Heidelberg, Germany.
authors.forename: Vincent P
authors.initials: VP
authors.lastname: Alibu
authors.forename: Christina
authors.initials: C
authors.lastname: Richter
authors.forename: Frank
authors.initials: F
authors.lastname: Voncken
authors.forename: Gabriela
authors.initials: G
authors.lastname: Marti
authors.forename: Sanjay
authors.initials: S
authors.lastname: Shahi
authors.forename: Christina Kunz
authors.initials: CK
authors.lastname: Renggli
authors.forename: Thomas
authors.initials: T
authors.lastname: Seebeck
authors.forename: Reto
authors.initials: R
authors.lastname: Brun
authors.forename: Christine
authors.initials: C
authors.lastname: Clayton
mesh_terms: D000818:Animals; D001152:Arsenicals / Q000494:pharmacology; D015153:Blotting, Western / Q000379:methods; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015870:Gene Expression; D006801:Humans; D008549:Melarsoprol / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D026901:Membrane Transport Proteins / Q000032:analysis / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000032:analysis / Q000096:biosynthesis / Q000502:physiology*; D021261:Parasitic Sensitivity Tests / Q000379:methods; D015800:Protozoan Proteins / Q000032:analysis / Q000096:biosynthesis / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017211:Treatment Failure; D014344:Trypanocidal Agents / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D014346:Trypanosoma brucei brucei / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014353:Trypanosomiasis, African / Q000188:drug therapy / Q000469:parasitology*
chemical_list: D001152:Arsenicals; D008549:Melarsoprol; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D015800:Protozoan Proteins; D014344:Trypanocidal Agents; C461386:MRPA protein, Trypanosoma brucei; C044719:melarsen oxide