Molecular mechanisms involved in gastrin-mediated regulation of cAMP-responsive promoter elements.
In the present study, we explore the role of cAMP-responsive (CRE) promoter elements in gastrin-mediated gene activation. By using the minimal CRE promoter reporter plasmid, pCRELuc, we show that gastrin can activate CRE. This activation is blocked by H-89 and GF 109203x, which inhibit protein kinases A and C, respectively. Moreover, Ca(2+)-activated pathways seem to be involved, because the calmodulin inhibitor W-7 reduced gastrin-mediated activation of pCRELuc. Deletion of CRE from the c-fos promoter rendered this promoter completely unresponsive to gastrin, indicating that CRE plays a central role in c-fos transactivation. Interestingly, gastrin-induced expression of the inducible cAMP early repressor (ICER), a gene that is known to be regulated by CRE promoter elements, was not reduced by H-89, W-7, or GF 109203x. Furthermore, bandshift analyses indicated that the region of the ICER promoter containing the CRE-like elements CARE 3-4 binds transcription factors that are not members of the CRE-binding protein-CRE modulator protein-activating transcription factor, or CREB/CREM/ATF-1, family. Our results underline the significance of the CRE promoter element in gastrin-mediated gene regulation and indicate that a variety of signaling mechanisms are involved, depending on the CRE promoter context.
Thommesen
L
L
Department of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, N-7489 Trondheim, Norway.
Hofsli
E
E
Paulssen
R H
RH
Anthonsen
M W
MW
Laegreid
A
A
D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005755:Gastrins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D017930:Genes, Reporter / Q000235:genetics; D016762:Genes, fos / Q000235:genetics; D008156:Luciferases / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D020218:Response Elements / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation; D014162:Transfection
D005755:Gastrins; D014157:Transcription Factors; D000242:Cyclic AMP; D008156:Luciferases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate