EFFECT OF L-ASPARAGINASE AND ASPARAGINE DEPRIVATION ON RNA-METABOLISM IN MOUSE LEUKEMIA L5178Y CELLS IN SUSPENSION CULTURE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 36  (10) , 3616-3621
Abstract
The effect of asparagine starvation and L-asparaginase on RNA metabolism of mouse leukemia cell lines L5178Y, whose growth is dependent on the presence of asparagine, and L5178Y-R, whose growth is independent of the presence of asparagine was analyzed. The deprivation of asparagine from the medium inhibited cellular protein synthesis by 30-40% of the control value in L5178Y cells, but not in L5178Y-R cells, whereas L-asparaginase inhibited synthesis by more than 80% in L5178Y and L5178-R cells. The decrease in protein synthesis caused by asparagine starvation in L5178Y cells was accompanied by a decrease in rRNA synthesis. The synthesis of rRNA was also blocked when L5178Y and L5178-R cells were exposed to L-asparaginase. The rate of synthesis of pulse labeled RNA decreased significantly in cells treated with L-asparaginase, and smaller pieces of polyadenylate containing pulse labeled RNA (presumptive mRNA) appeared among monosomes and polysomes. The rate of mRNA synthesis was constant during asparagine starvation, and a marked accumulation of monosome was observed.