Article: article from journal or magazin.
Epidermal growth factor (EGF) stimulation of cultured brain cells. II. Increased production of extracellular soluble proteins.
Developmental Brain Research
The production of extracellular soluble proteins was studied in serum-free aggregating cell cultures of fetal rat telencephalon labeled on culture day 7 with a mixture of radioactive amino acid precursors. Cultures treated continuously with epidermal growth factor (EGF; 20 ng/ml) showed a generally increased protein secretion and a particularly enhanced production of a few distinct extracellular proteins. The time lag of this response after an initial dose of EGF (25 ng/ml) on day 7 was 48 h. The total macromolecular radioactivity that accumulated within 96 h of labeling in the media of EGF-treated cultures was 175% of untreated controls, whereas no difference was found in the proportions of intracellular amino acid incorporation. Cultures which received a single dose of EGF (25 ng/ml) on day 1 showed still a greatly increased protein secretion on day 7. Prevention of extracellular protein accumulation by reducing the initial cell number and increasing the rate of media changes did not affect the EGF-induced stimulation of the two glial enzymes, glutamine synthetase and 2',3'-cyclic nucleotide 3'-phosphohydrolase. The results suggest that both the increased production of extracellular proteins and the enhanced development of glial enzymatic activities reflect the stimulated phenotypic expression of EGF-sensitive brain cells.
2',3'-Cyclic Nucleotide 3'-Phosphodiesterase, 2',3'-Cyclic-Nucleotide Phosphodiesterases/metabolism, Animals, Cell Aggregation, Cells, Cultured, Epidermal Growth Factor/pharmacology, Fetus, Glutamate-Ammonia Ligase/metabolism, Nerve Tissue Proteins/biosynthesis, Neuroglia/enzymology, Phosphoric Diester Hydrolases, Rats, Rats, Inbred Strains, Telencephalon/metabolism
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