Identification of a bimodal regulatory element encompassing a canonical AP-1 binding site in the proximal promoter region of the human decorin gene.
We have previously described a tumor necrosis factor alpha (TNF-alpha) response element, located between residues -188 and -140 of the human decorin promoter, that mediates the inhibitory effect of TNF-alpha on decorin gene expression (Mauviel, A., Santra, M., Chen, Y.-Q., Uitto, J., and Iozzo, R. V. (1995) J. Biol. Chem. 270, 11692-11700). In this report, we demonstrate that interleukin 1 (IL-1), a pleiotropic cytokine that shares a wide variety of biological properties with TNF-alpha, uses the same cis element to up-regulate decorin gene expression. Specifically, IL-1 enhances the expression of the human decorin gene, and this effect is mediated by activation of the corresponding promoter, as shown in transient cell transfection experiments using decorin promoter-chloramphenicol acetyl transferase reporter gene constructs. Additional transfection experiments with various 5'-deletion promoter-chloramphenicol acetyltransferase constructs demonstrate that both the inhibitory effect of TNF-alpha and the stimulatory effect of IL-1 are mediated by a 48-base pair segment of the promoter, between residues -188 and -140. This region, which contains a canonical AP-1 binding site, TGAGTCA, allows an antagonistic effect of these two cytokines on the decorin promoter activity. When cloned upstream of the thymidine kinase promoter, this promoter fragment requires the AP-1 sequence to be responsive to IL-1. Supershift assays with various AP-1 antibodies identified c-Jun, Jun-B, and Fra-1 as components of the complex binding to the decorin promoter. Overexpression of c-jun, an oncogene encoding the c-Jun/AP-1 transcription factor, reduces the basal activity of both decorin and -188/-140 thymidine kinase promoter constructs. In contrast, blockage of c-jun expression with an antisense c-jun construct potentiates the stimulatory effect of IL-1 and reverses the response to TNF-alpha. These data indicate that the region between residues -188 and -140 of the human decorin promoter functions as a bimodal regulatory element and allows transcriptional repression by c-Jun/AP-1 complexes.
Mauviel
A
A
Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Korang
K
K
Santra
M
M
Tewari
D
D
Uitto
J
J
Iozzo
R V
RV
D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D058575:Decorin; D016326:Extracellular Matrix Proteins; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011509:Proteoglycans / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D012867:Skin / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013937:Thymidine Kinase / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
C546878:DCN protein, human; D058575:Decorin; D016326:Extracellular Matrix Proteins; D007375:Interleukin-1; D011509:Proteoglycans; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D013937:Thymidine Kinase