Glucocorticoid-regulated expression from the 5'-flanking region of the rat alpha 1-acid glycoprotein gene. Requirement for ongoing protein synthesis.
The induction of alpha 1-acid glycoprotein (AGP) mRNA by glucocorticoids in rat hepatoma cells requires ongoing protein synthesis. Here we show that the 5'-flanking region of the AGP gene confers glucocorticoid responsiveness on the expression of heterologous coding sequences. Moreover, the induction of beta-globin mRNA directed by the AGP promoter is inhibited by concurrent treatment with cycloheximide, thereby suggesting that the requirement for protein synthesis is mediated through 5'-flanking sequences. Analysis of the effects of varying durations of cycloheximide treatment indicates that both the endogenous AGP gene and the transfected AGP-beta-globin chimeric gene are induced normally by dexamethasone during the first 1-2h of concurrent treatment. In addition, pretreatment with cycloheximide yields a decrease in the subsequent induction of both beta-globin and AGP RNAs. These data support the notion that a pre-existing and labile protein, perhaps in concert with the glucocorticoid receptor, acts through the 5'-flanking region of the AGP gene to stimulate transcription from the AGP promoter.
D000818:Animals; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D005796:Genes / Q000187:drug effects*; D005914:Globins / Q000096:biosynthesis / Q000235:genetics; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D009961:Orosomucoid / Q000096:biosynthesis / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects*
D009961:Orosomucoid; D012333:RNA, Messenger; D003907:Dexamethasone; D005914:Globins; D003513:Cycloheximide