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Full-Text Articles in Cell and Developmental Biology
Hypoxanthine-Induced Differentiation Of Cultured Human Leukemia Cells, Gayle Jennette Singleton
Hypoxanthine-Induced Differentiation Of Cultured Human Leukemia Cells, Gayle Jennette Singleton
Chemistry & Biochemistry Theses & Dissertations
Human cultured leukemia cells appear to have a decreased amount of inosine in their tRNA. When cells with inosine deficient tRNA are placed in a hypoxanthine fortified media, they incorporate hypoxanthine into their tRNA by the action of the enzyme tRNA-hypoxanthine ribosyl transferase. This generates the nucleoside inosine in the tRNA. The cultured human leukemia cell lines, CCRF-CEM, HL-60, and HGPRT(-) HL- 60, incorporate hypoxanthine into their tRNA, as determined by tRNA isolation, hydrolysis, and HPLC analysis. Hypoxanthine treatment dramatically inhibited cell growth in conjunction with partial induction of differentiation in the CCRF-CEM, HL-60, and HGPRT ( - ) HL-60 …
Modulation Of Queuine Uptake In Cultured Human Fibroblasts By Phorbol Esters And Interferons, Debra L. Crane
Modulation Of Queuine Uptake In Cultured Human Fibroblasts By Phorbol Esters And Interferons, Debra L. Crane
Chemistry & Biochemistry Theses & Dissertations
Queuosine, a nucleoside found exclusively in the first position of the anticodon of transfer RNA (tRNA), is generated post-transcriptionally in an exchange of guanine for queuine by the modifying enzyme tRNA-guanine ribosyltransferase. Phorbol ester tumor promoters were shown to induce queuine hypomodified tRNA, and that phorbol ester action was due, in part, to inhibition of queuine transport across the cell membrane. An unidentified protein designated conditioned medium factor (CMF) that potentiated a phorbol-induced inhibition of queuine uptake was also documented. We suggest here that phorbol ester-induced inhibition of queuine uptake is not a significant factor in inducing queuine-deficient tRNA although …