Glucocorticoid-mediated down regulation of c-fos mRNA in C6 glioma cells: lack of correlation with proenkephalin mRNA.
We investigate the linkage between the transcriptional factor, c-fos, and expression of proenkephalin in rat C6 glioma cells. C6 cells contained abundant levels of c-fos mRNA. Treatment of cells with dexamethasone resulted in a 10-fold decline in c-fos transcripts and a small increase in proenkephalin mRNA. Combined exposure to dexamethasone and isoproterenol also induced a decrease in c-fos mRNA while proenkephalin mRNA increased 8-fold. Treatment of the C6 cells with phorbol 12-myristate 13-acetate caused a 13-fold increase in c-fos expression 0.5 h after administration and a decrease in proenkephalin mRNA. These data indicate that c-fos and proenkephalin mRNA are not regulated in a sequential, parallel manner, that newly synthesized c-fos is not the determining factor controlling proenkephalin gene regulation, and that c-fos expression is under negative control by glucocorticoids.
Yin
J
J
Department of Biochemistry and Molecular Biology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark 07103.
Howells
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RD
D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000502:physiology; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004745:Enkephalins / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016762:Genes, fos / Q000187:drug effects*; D005910:Glioma; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004745:Enkephalins; D011498:Protein Precursors; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; C029992:proenkephalin; D003907:Dexamethasone; D007545:Isoproterenol; D013755:Tetradecanoylphorbol Acetate