title: Changes in amount of hypo-modified tRNA having guanine in place of queuine during erythroid differentiation of murine erythroleukemia cells.
abstract: The amounts of hypo-modified tRNAs having guanine in place of queuine in murine erythroleukemic cells decreased markedly when the cells differentiated into mature erythroid cells. The amounts of these hypo-modified tRNAs can be determined easily by measuring incorporation of labeled guanine into tRNA with Escherichia coli tRNA--guanine transglycosylase. The decrease was detected at on early stage of erythroid differentiation: namely, before any detectable increase in the percentage of cells containing hemoglobin. The amount of guanine-accepting tRNA species was nearly proportional to the percentage of undifferentiated cells in the population, regardless of the type of inducer used. Decrease in the amounts of hypo-modified tRNAs in the cells was effectively blocked by 12-O-tetradecanoylphorbol 13-acetate, which inhibits differentiation of these cells. 8-Azaguanine, which is known to be substrate of tRNA--guanine transglycosylase, was incorporated almost exclusively into the first position of hypo-modified tRNA in murine erythroleukemic cells when they were pulse-labeled in culture with 8-azaguanine, suggesting strongly that tRNA-guanine transglycosylase in the cells is actually involved in incorporation of 8-azaguanine into tRNA in vivo. The amount of 8-azaguanine incorporated into tRNA in differentiated cells was one third of that in undifferentiated cells, the decrease being parallel with that in the amount of guanine-accepting tRNA in these cells. The results suggest that the appearance of hypo-modified tRNAs in the transformed cells was due to lack of substrate for queuosine biosynthesis in tRNA.
mesh_terms: D000818:Animals; D001375:Azaguanine / Q000378:metabolism; D002454:Cell Differentiation; D006147:Guanine / Q000031:analogs & derivatives* / Q000032:analysis*; D007942:Leukemia, Experimental / Q000503:physiopathology*; D051379:Mice; D012343:RNA, Transfer / Q000096:biosynthesis / Q000302:isolation & purification*
chemical_list: D006147:Guanine; C019549:queuine; D012343:RNA, Transfer; D001375:Azaguanine