Deoxyadenosine-resistant human T lymphoblasts with elevated 5'-nucleotidase activity.
Although several different enzymes with 5'-nucleotidase activity have been described in mammalian cells, their functions in nucleotide metabolism have not been clearly distinguished. In the present experiments, a mutant human T lymphoblastoid cell line (CEM-dAdoR) was selected specifically for resistance to deoxyadenosine toxicity. Compared to parental CEM cells, the variant had 4-fold elevated ATP-activated cytosolic 5'-nucleotidase activity. Other enzymes of potential importance for deoxyadenosine metabolism were indistinguishable in the two cell types. In medium supplemented with the adenosine deaminase inhibitor deoxycoformycin, the T cells with increased 5'-nucleotidase accumulated less nucleotides from exogenously added deoxyadenosine, or 9-beta-D-arabinofuranosyladenine, than did parental T lymphocytes. These metabolic changes were associated with resistance to the growth inhibitory effects of these nucleosides, and also to deoxyguanosine and to 9-beta-D-arabinofuranosylguanine. The T cells with elevated 5'-nucleotidase activity formed more 2',3'-dideoxyadenosine than did parental cells, in deoxycoformycin-supplemented medium. The accumulation of 2',3'-dideoxyadenosine 5'-triphosphate from 2',3'-dideoxyinosine was similarly augmented in the mutant. These data establish the importance of the cytosolic 5'-nucleotidase for the metabolism of purine 2'-deoxyribonucleosides, arabinonucleosides and 2',3'-dideoxyribonucleosides in T lymphoblasts.
Carson
D A
DA
Department of Medicine, University of California, San Diego, La Jolla.
Carrera
C J
CJ
Wasson
D B
DB
Iizasa
T
T
D015720:5'-Nucleotidase / Q000032:analysis*; D000255:Adenosine Triphosphate / Q000502:physiology; D000998:Antiviral Agents / Q000378:metabolism; D001087:Arabinonucleosides / Q000378:metabolism; D002460:Cell Line; D003839:Deoxyadenosines / Q000494:pharmacology* / Q000633:toxicity; D015224:Dideoxynucleosides / Q000378:metabolism / Q000494:pharmacology; D004351:Drug Resistance; D004789:Enzyme Activation; D006678:HIV / Q000187:drug effects; D006801:Humans; D011684:Purine Nucleosides / Q000378:metabolism / Q000494:pharmacology; D011685:Purine Nucleotides / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology*
D000998:Antiviral Agents; D001087:Arabinonucleosides; D003839:Deoxyadenosines; D015224:Dideoxynucleosides; D011684:Purine Nucleosides; D011685:Purine Nucleotides; D000255:Adenosine Triphosphate; D015720:5'-Nucleotidase