The cAMP Response Element Binding Protein Synergizes with Other Transcription Factors to Mediate cAMP Responsiveness (∗)

• Published in: The Journal of biological chemistry Vol. 270; no. 14; pp. 8225 - 8232
• Main Authors: Roesler, William J., Graham, Janet G., Kolen, Richard, Klemm, Dwight J., McFie, Pamela J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07-04-1995; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Cell Line; Cyclic AMP - metabolism; Cyclic AMP Response Element-Binding Protein - genetics; Cyclic AMP Response Element-Binding Protein - metabolism; DNA-Binding Proteins; Fungal Proteins - genetics; Fungal Proteins - metabolism; Humans; Liver - metabolism; Molecular Sequence Data; Phosphoenolpyruvate Carboxykinase (GTP) - genetics; Promoter Regions, Genetic; Saccharomyces cerevisiae Proteins; Sequence Alignment; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.14.8225

The cAMP responsiveness of the promoter for phosphoenolpyruvate carboxykinase (EC 4.1.1.32) is mediated by a synergistic interaction between a complex regulatory region, which binds liver-enriched transcription factors, and a typical cAMP response element (CRE). Although a role for the CRE-binding protein (CREB) in the cAMP-responsiveness of this promoter has been generally assumed, some uncertainty remains due to the observations that several C/EBP-related proteins bind with near equal affinity, relative to CREB, to this particular CRE. Thus, a detailed analysis of the involvement of CREB in this synergism was undertaken in HepG2 cells. Gel mobility shift assays demonstrate that a CRE probe is bound by CREB present in HepG2 cells. Furthermore, we show that a dominant repressor of CREB is able to significantly reduce the cAMP responsiveness of the PEPCK promoter in HepG2 cells. Finally, we demonstrate using a GAL4-CREB fusion protein that CREB is able to synergize with the liver-enriched factors bound upstream on the PEPCK promoter to mediate a liver-specific response to cAMP. Examination of several mutant forms of CREB allow us to conclude that the “synergy” domain of CREB resides within amino acid residues 83-203, and that residues 83-145 can mediate a partial synergistic response. This study establishes that CREB is able to synergize with liver-enriched transcription factors to mediate a tissue-specific response to cAMP.