Transcriptional regulation of corticotropin-releasing hormone-binding protein gene expression in astrocyte cultures.
The molecular mechanisms involved in regulation of CRH-binding protein (CRH-BP) gene expression were examined using primary rat astrocyte cultures. The cells were treated with various regulators, and CRH-BP messenger RNA (mRNA) levels were determined using ribonuclease protection assays. Forskolin (Fsk, 10 microM) or 12-O-tetradecanoyl-phorbol 13-acetate (TPA, 100 nM) increases CRH-BP mRNA levels up to 30 times control level, and together they act synergistically to increase CRH-BP gene expression up to 100 times control levels. CRH can also positively regulate CRH-BP gene expression to 6.1 times control levels. All of these increases in steady-state CRH-BP mRNA levels can be repressed by dexamethasone, a synthetic glucocorticoid. To determine whether these changes in steady-state CRH-BP mRNA levels are caused by altered transcription or RNA stability, heteronuclear (hn) CRH-BP species were examined using ribonuclease protection assays. CRH-BP hnRNA transcripts can be detected transiently after the addition of Fsk or TPA, and dexamethasone can repress Fsk- or TPA-induced CRH-BP hnRNA levels in this assay. These results demonstrate that CRH, glucocorticoids, and the protein kinase A and protein kinase C signaling pathways are involved in regulation of CRH-BP gene expression in astrocyte cultures, and that this regulation is caused, at least in part, by altered transcription of the gene.
McClennen
S J
SJ
Department of Biological Chemistry, The University of Michigan, Ann Arbor 48109, USA.
Seasholtz
A F
AF
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology*; D005938:Glucocorticoids / Q000494:pharmacology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000502:physiology*
D002352:Carrier Proteins; D005938:Glucocorticoids; D012333:RNA, Messenger; C067133:corticotropin releasing factor-binding protein; D005576:Colforsin; D003907:Dexamethasone; D013755:Tetradecanoylphorbol Acetate