title: Transport of antiviral 3'-deoxy-nucleoside drugs by recombinant human and rat equilibrative, nitrobenzylthioinosine (NBMPR)-insensitive (ENT2) nucleoside transporter proteins produced in Xenopus oocytes.
abstract: In the present study, one has determined the relative role of plasma membrane equilibrative (Na+-independent) ENT nucleoside transport proteins (particularly ENT2) in the uptake of antiviral nucleoside analogues for comparison with the previously reported drug transport properties of concentrative (Na+-dependent) CNT nucleoside transport proteins. The human and rat nucleoside transport proteins hENT1, rENT1, hENT2 and rENT2 were produced in Xenopus oocytes and investigated for their ability to transport three 3'-deoxy-nucleoside analogues, ddC (2'3'-dideoxycytidine), AZT (3'-azido-3'-deoxythymidine) and ddI (2'3'-dideoxyinosine), used in human immunodeficiency virus (HIV) therapy. The results show, for the first time, that the ENT2 transporter isoform represents a mechanism for cellular uptake of these clinically important nucleoside drugs. Recombinant h/rENT2 transported ddC, ddI and AZT, whilst h/rENT1 transported only ddC and ddI. Relative to uridine, h/rENT2 mediated substantially larger fluxes of ddC and ddI than h/rENT1. Transplanting the amino-terminal half of rENT2 into rENT1 rendered rENT1 transport-positive for AZT and enhanced the uptake of both ddC and ddI, identifying this region as a major site of 3'-deoxy-nucleoside drug interaction.
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Canada.
authors.forename: S Y
authors.initials: SY
authors.lastname: Yao
authors.forename: A M
authors.initials: AM
authors.lastname: Ng
authors.forename: M
authors.initials: M
authors.lastname: Sundaram
authors.forename: C E
authors.initials: CE
authors.lastname: Cass
authors.forename: S A
authors.initials: SA
authors.lastname: Baldwin
authors.forename: J D
authors.initials: JD
authors.lastname: Young
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019380:Anti-HIV Agents / Q000378:metabolism*; D001692:Biological Transport; D016049:Didanosine / Q000378:metabolism*; D033721:Equilibrative Nucleoside Transporter 1; D033722:Equilibrative-Nucleoside Transporter 2; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors / Q000378:metabolism*; D014982:Xenopus laevis; D016047:Zalcitabine / Q000378:metabolism*; D015215:Zidovudine / Q000378:metabolism*
chemical_list: D019380:Anti-HIV Agents; D033721:Equilibrative Nucleoside Transporter 1; D033722:Equilibrative-Nucleoside Transporter 2; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D018894:Reverse Transcriptase Inhibitors; C438649:SLC29A1 protein, human; C438654:SLC29A2 protein, human; C438652:Slc29a1 protein, rat; C438655:Slc29a2 protein, rat; D015215:Zidovudine; D016047:Zalcitabine; D016049:Didanosine