Localization and activity of multidrug resistance protein 1 in the secretory pathway of Leishmania parasites.
Upregulation of the multidrug resistance protein 1 (LeMDR1) in the protozoan parasite, Leishmania enriettii, confers resistance to hydrophobic drugs such as vinblastine, but increases the sensitivity of these parasites to the mitochondrial drug, rhodamine 123. In order to investigate the mechanism of action of LeMDR1, the subcellular localization of green fluorescent protein (GFP)-tagged versions of LeMDR1 and the fate of the traceable-fluorescent LeMDR1 substrate calcein AM were examined in both Leishmania mexicana and L. enriettii LeMDR1 -/- and overexpressing cell lines. The LeMDR1-GFP chimera was localized by fluorescence microscopy to a number of secretory and endocytic compartments, including the Golgi apparatus, endoplasmic reticulum (ER) and a multivesicular tubule (MVT)-lysosome. Pulse-chase labelling experiments with calcein AM suggested that the Golgi and ER pools, but not the MVT-lysosome pool, of LeMDR1 were active in pumping calcein AM out of the cell. Cells labelled with calcein AM under conditions that slow vesicular transport (low temperature and stationary growth) inhibited export and resulted in the accumulation of fluorescent calcein in both the Golgi and the mitochondria. We propose that LeMDR1 substrates are pumped into secretory compartments and exported from the parasite by exocytosis. Accumulation of MDR substrates in the ER can result in alternative transport to the mitochondrion, explaining the reciprocal sensitivity of drug-resistant Leishmania to vinblastine and rhodamine 123.
Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
Matthew A
MA
Dodge
Ross F
RF
Waller
Larry M C
LM
Chow
Muhammad M
MM
Zaman
Leanne M
LM
Cotton
Malcolm J
MJ
McConville
Dyann F
DF
Wirth
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology; D001692:Biological Transport; D002460:Cell Line; D018432:Drug Resistance, Multiple / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005452:Fluoresceins / Q000494:pharmacology; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins; D018313:Leishmania enriettii / Q000187:drug effects / Q000378:metabolism*; D007894:Leishmania mexicana / Q000187:drug effects / Q000378:metabolism*; D007896:Leishmaniasis / Q000188:drug therapy*; D008164:Luminescent Proteins / Q000378:metabolism; D015800:Protozoan Proteins / Q000032:analysis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020112:Rhodamine 123 / Q000494:pharmacology; D014747:Vinblastine / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000981:Antiprotozoal Agents; D005452:Fluoresceins; D008164:Luminescent Proteins; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C085925:calcein AM; D020112:Rhodamine 123; D014747:Vinblastine