Glucocorticoid-dependent induction of the mRNA coding for argininosuccinate lyase in cultured fetal rat hepatocytes.

Dexamethasone increased both argininosuccinate lyase (ASL) activity and specific mRNA level in cultured fetal hepatocytes. Addition of various inhibitors of RNA synthesis showed that the increase in ASL mRNA may be related to an enhancement of ASL gene transcription, but not to a specific messenger stabilization. An apparent half-life of about 12 h for ASL mRNA was found in both untreated and dexamethasone-treated hepatocytes. About 30 h were necessary to observe the maximal effect of dexamethasone, and, in addition, both puromycin and cycloheximide (two inhibitors of protein synthesis) blocked the inducing effect of the steroid. These results suggested the involvement of intermediary protein(s) in the mechanism of induction of ASL mRNA by glucocorticoids.