Novel Negative Regulatory Element in the Platelet-derived Growth Factor B Chain Promoter That Mediates ERK-dependent Transcriptional Repression

• Published in: The Journal of biological chemistry Vol. 275; no. 15; pp. 11478 - 11483
• Main Authors: Rafty, Louise A., Khachigian, Levon M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 14.04.2000; American Society for Biochemistry and Molecular Biology
• Subjects: Base Sequence; Cells, Cultured; ERK1 protein; Mitogen-Activated Protein Kinases - physiology; Molecular Sequence Data; Muscle, Smooth, Vascular - cytology; Platelet-Derived Growth Factor - genetics; Promoter Regions, Genetic; Repressor Proteins - physiology
• DOI: 10.1074/jbc.275.15.11478
• ISSN: 0021-9258

Platelet-derived growth factor (PDGF), which consists of an A and/or B chain, stimulates migration and proliferation in vascular smooth muscle cells as well as a large number of other cell types. Investigations over recent years have defined roles for several positive regulatory transcription factors in the PDGF-B promoter. However, little is known about the transcriptional mechanisms that negatively regulate this gene. Here, we used transient transfection and 5′ deletion analysis to define a specific region in the PDGF-B promoter-mediating repression in vascular smooth muscle cells. Gel retardation assays revealed this region is bound by nuclear protein(s) in a specific manner. Supershift assays excluded the direct association of Sp1, Sp3, and Egr-1. Mutation of the negative regulatory element no longer supported nucleoprotein complex formation and, when introduced into the PDGF-B promoter, rescued the promoter from repression. Promoter activity was also restored by transfection of oligonucleotide decoys bearing the repressor binding site. The MEK1/2 inhibitor, PD98059, and a dominant negative construct generating inactive ERK1 increased reporter expression driven by the PDGF-B promoter. In contrast, the MEK inhibitor had no effect on the activity of the mutant PDGF-B promoter. These effects were cell type-specific, since neither suppression of the PDGF-B promoter nor nucleoprotein complex formation was observed in vascular endothelial cells. These findings define a distinct negative regulatory element in the PDGF-B promoter that interacts with nuclear protein(s) and inhibits PDGF-B promoter-dependent gene expression in an ERK-dependent manner.