Characterization of three different elements in the 5'-flanking region of the fibronectin gene which mediate a transcriptional response to cAMP.
A cAMP regulatory element (CRE) at nucleotide position -170 of the fibronectin gene was characterized previously (Dean, D. C., Blakeley, M. S., Newby, R. F., Ghazal, P., Hennighausen, L., and Bourgeois, S. (1989) Mol. Cell. Biol. 9, 1498-1506). Here we identify two additional low affinity CREs at nucleotide positions -260 and -415 which differ in sequence by 1 base pair. Interestingly, these CREs did not compete for binding of nuclear proteins in gel retardation assays and partial tryptic digestion of protein-DNA complexes produced a different pattern with each CRE, indicating that they bind different proteins. CRE (-170) competed for binding of proteins to both CREs, suggesting that it may represent a composite of the two elements. CRE (-415) competed effectively for binding of nuclear proteins to the somatostatin gene CRE, suggesting that, like the somatostatin CRE, it binds the nuclear protein CREB. On the other hand, CRE (-260) appears to bind the nuclear protein PEA-2, which also binds a site in the polyoma virus enhancer. In summary, disruption of dyad symmetry in the 3' region of the CRE, as occurs with CRE (-260) and CRE (-415), results in a lower affinity site and may also change the specificity for different nuclear proteins.
Bowlus
C L
CL
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
McQuillan
J J
JJ
Dean
D C
DC
D001483:Base Sequence; D001667:Binding, Competitive; D000242:Cyclic AMP / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics*; D005809:Genes, Regulator; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D010449:Peptide Mapping; D010957:Plasmids; D014158:Transcription, Genetic; D014357:Trypsin
D005353:Fibronectins; D009687:Nuclear Proteins; D000242:Cyclic AMP; D014357:Trypsin