title: Expression of the plasmodial pfmdr1 gene in mammalian cells is associated with increased susceptibility to chloroquine.
abstract: Chloroquine (CQ)-resistant (CQR) Plasmodium falciparum malaria parasites show a strong decrease in CQ accumulation in comparison with chloroquine-sensitive parasites. Controversy exists over the role of the plasmodial pfmdr1 gene in the CQR phenotype. pfmdr1 is a member of the superfamily of ATP-binding cassette transporters. Other members of this family are the mammalian multidrug resistance genes and the CFTR gene. We have expressed the pfmdr1-encoded protein, Pgh1, in CHO cells and Xenopus oocytes. CHO cells expressing the Pgh1 protein demonstrated an increased, verapamil-insensitive susceptibility to CQ. Conversely, no increase in drug susceptibility to primaquine, quinine, adriamycin, or colchicine was observed in Pgh1-expressing cells. CQ uptake experiments revealed an increased, ATP-dependent accumulation of CQ in Pgh1-expressing cells over the level in nonexpressing control cells. The increased CQ accumulation in Pgh1-expressing cells coincided with an enhanced in vivo inhibition of lysosomal alpha-galactosidase by CQ. CHO cells expressing Pgh1 carrying two of the CQR-associated Pgh1 amino acid changes (S1034C and N1042D) did not display an increased CQ sensitivity. Immunofluorescence experiments revealed an intracellular localization of both mutant and wild-type forms of Pgh1. We conclude from our results that wild-type Pgh1 protein can mediate an increased intracellular accumulation of CQ and that this function is impaired in CQR-associated mutant forms of the protein. We speculate that the Pgh1 protein plays an important role in CQ import in CQ-sensitive malaria parasites.
authors.affiliation: Department of Medicine, McGill University, Montréal, Québec, Canada.
authors.forename: H H
authors.initials: HH
authors.lastname: van Es
authors.forename: S
authors.initials: S
authors.lastname: Karcz
authors.forename: F
authors.initials: F
authors.lastname: Chu
authors.forename: A F
authors.initials: AF
authors.lastname: Cowman
authors.forename: S
authors.initials: S
authors.lastname: Vidal
authors.forename: P
authors.initials: P
authors.lastname: Gros
authors.forename: E
authors.initials: E
authors.lastname: Schurr
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000378:metabolism / Q000633:toxicity*; D003078:Colchicine / Q000633:toxicity; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D016054:DNA, Protozoan / Q000235:genetics / Q000378:metabolism; D004317:Doxorubicin / Q000633:toxicity; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D017125:Genes, Protozoan; D008565:Membrane Proteins / Q000235:genetics; D016376:Oligonucleotides, Antisense; D009865:Oocytes / Q000378:metabolism; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics*; D011319:Primaquine / Q000633:toxicity; D015800:Protozoan Proteins / Q000096:biosynthesis* / Q000378:metabolism; D011803:Quinine / Q000633:toxicity; D015183:Restriction Mapping; D014700:Verapamil / Q000494:pharmacology; D014747:Vinblastine / Q000633:toxicity; D014982:Xenopus laevis
chemical_list: D018528:ATP-Binding Cassette Transporters; D016054:DNA, Protozoan; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D015800:Protozoan Proteins; C059987:mdr gene protein, Plasmodium; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D014747:Vinblastine; D004317:Doxorubicin; D002738:Chloroquine; D000255:Adenosine Triphosphate; D011803:Quinine; D014700:Verapamil; D011319:Primaquine; D003078:Colchicine