Premium
Regulation of the preprotachykinin‐I gene promoter through a protein kinase A‐dependent, cyclic AMP response element‐binding protein‐independent mechanism
Author(s) -
CalinJageman Irina E.,
Wang Jun,
Ban Michael J.
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.03738.x
Subject(s) - mechanism (biology) , protein kinase a , gene , microbiology and biotechnology , response element , chemistry , biology , kinase , biochemistry , promoter , gene expression , philosophy , epistemology
Preprotachykinin‐I ( PPT ) gene expression is regulated by a number of stimuli that signal through cyclic AMP (cAMP)‐mediated pathways. In the present study, forskolin, an adenylyl cyclase stimulator, significantly increased PPT mRNA levels in PPT‐expressing RINm5F cells, an effect paralleled by an increase in PPT promoter‐luciferase reporter construct activity. The forskolin‐induced stimulation of PPT transcription was protein kinase A dependent (PKA), as shown by blockade with the PKA inhibitor N ‐[2‐( p ‐bromocinnamylamino) ethyl]‐5‐isoquinolinesulfonamide. We found that the activation protein 1/cAMP response element (AP1/CRE) site centered at − 196 relative to the transcription start site was important for basal and forskolin‐induced PPT promoter activity. Because of the involvement of PKA and the similarity of the AP1/CRE element to consensus CRE sequences, we investigated the role of CRE‐binding protein (CREB) in the regulation of the PPT promoter. Surprisingly, overexpression of a dominant‐negative CREB (i.e. CREB‐A) did not affect basal or forskolin‐induced PPT promoter activity. Furthermore, binding of CREB to the PPT promoter AP1/CRE site was not demonstrable in electrophoretic mobility shift assays. Rather, our experiments suggested that c‐Jun is a member of the complex that binds to this site. We conclude that, at least in RINm5F cells, cAMP‐mediated up‐regulation of PPT gene expression does not involve CREB or CREB‐related transcription factor recruitment to the AP1/CRE site.