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Derepression of the Glutamine Synthetase in Neuroblastoma Cells at Low Concentrations of Glutamine
Author(s) -
Lacoste Lucille,
Chaudhary Kapil Dev,
Lapointe Jacques
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb04703.x
Subject(s) - glutamine synthetase , glutamine , cycloheximide , derepression , biochemistry , enzyme , biology , microbiology and biotechnology , protein biosynthesis , amino acid , gene expression , gene , psychological repression
Regulation of the biosynthesis of glutamine synthetase was studied in neuroblastoma cells (Neuro‐2A) by use of a recently developed, sensitive radioisotopic assay. The removal of glutamine from the culture medium of these cells for 24 h resulted in a 10‐fold increase in glutamine synthetase specific activity (15‐fold after 2 weeks) compared with the basal level found in cells grown in the presence of 2 m M glutamine. Following the growth of these cells for 2 weeks in the presence of various concentrations of glutamine, a negative linear correlation was observed between the specific activity of glutamine synthetase (from 1.7 to 0.14 unit/mg) and the concentration of glutamine in the growth medium (from 0.5 to 2 m M ). Cycloheximide or actinomycin D blocked the increase in glutamine synthetase activity observed in the absence of glutamine. These results suggest that the removal of glutamine led to the induction of glutamine synthetase by stimulating new enzyme synthesis. The enzyme was not degraded, but only diluted, by growth upon readdition of glutamine to the medium. The influence of glutamine depletion is also reported for C‐6 glioma cells and glial cells in primary cultures.