Glucocorticoid induction of CRE-binding protein isoform mRNAs in rat C6 glioma cells.

Mammalian cells express several distinct isoforms of transcription factor CREB (cAMP-responsive element binding protein). At least two forms, alpha- and delta CREB, arise through alternative splicing of the CREB gene transcript. In this communication we demonstrate that the mRNAs of several CREB isoforms are expressed in rat C6 glioma cells and that the intracellular levels of these mRNAs are markedly induced by the synthetic glucocorticoid dexamethasone. Nuclear run-off assays show that the induction occurs, at least in part, through a transcriptional mechanism. The enhanced cellular levels of CREB mRNAs are accompanied by increased CREB protein and CRE-binding activity of nuclear extracts as evaluated by immunoblot and Southwestern blot assays.