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Identification of a novel point mutation in ENT1 that confers resistance to Ara‐C in human T cell leukemia CCRF‐CEM cells
Author(s) -
Zimmerman Eric I.,
Huang Min,
Leisewitz Andrea V.,
Wang Yanhong,
Yang Jing,
Graves Lee M.
Publication year - 2009
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2008.12.041
Subject(s) - nucleoside , missense mutation , mutant , point mutation , mutation , chemistry , arginine , biochemistry , microbiology and biotechnology , biology , gene , amino acid
The genetic basis for the Ara‐C resistance of CCRF‐CEM Ara‐C/8C leukemia cells was investigated. DNA sequencing revealed that these cells expressed an equilibrative nucleoside transporter 1 (ENT1) with a single missense mutation resulting in glycine to arginine replacement (G24R). To test the importance of this residue, additional G24 mutants were created and examined for [3H]‐uridine and [3H]‐Ara‐C uptake. Both a G24E and G24A mutant showed reduced ENT1‐dependent activity. An EGFP‐tagged G24R ENT1 displayed plasma membrane localization even though it was unable to bind [3H]‐NBMPR, an ENT1‐specific inhibitor. These results define G24 as critical amino acid for ENT1 nucleoside uptake and suggest that mutations in TM1 may provide a mechanism for Ara‐C resistance in CCRF‐CEM Ara‐C/8C cells.