Nicotine-induced gene expression of proenkephalin in bovine chromaffin cells

✍ Scribed by Wang, X. ;Bacher, B. ;H�llt, V.

• Publisher: Springer-Verlag
• Year: 1994
• Tongue: English
• Weight: 596 KB
• Volume: 72
• Category: Article
• ISSN: 1432-1440
• DOI: 10.1007/bf00190754

✦ Synopsis

The induction of the proenkephalin gene by nicotine has been characterized in bovine adrenal medullary chromaffin cells. Nicotine (10 gM) caused an approximately fourfold increase in the proenkephalin m R N A levels within 24 h. The half-life of the proenkephalin m R N A in nicotine-stimulated cells was similar to that in control cells (about 13 h), indicating that nicotine does not affect m R N A stability but acts at the levels of proenkephalin gene transcription. This was also supported by experiments showing that the expression of a proenkephalin chloramphenicol acetyl transferase reporter gene (PENKCAT-153/+50) containing 153 nucleotides of upstream promoter sequences is increased (about twofold) by nicotine after transient transfection in the chromaffin cells. In addition, nicotine induced a marked elevation of the immediate early gene mRNAs c-fos, c-jun, and jun-B. Maximally increased levels for c-fos m R N A (about 100-fold) were obtained after 20 rain. c-jun and jun-B were increased three-to fivefold 60 min after nicotine addition. The expression of PENKCAT-153/+ 53 and of a proenkephalin gene reporter plasmid which contains a dimer of the enkephalin cAMP responsive element 2 (ENKCRE-2) in front of a minimal promoter was increased by cotransfection of a c-fos expression plasmid, indicating that nicotine may induce the proenkephalin gene in chromaffin cells via c-Fos which binds to the ENKCRE-2 element.