FGF-1-induced platelet-derived growth factor-A chain gene expression in endothelial cells involves transcriptional activation by early growth response factor-1.
Fibroblast growth factor-1 (FGF-1), a prototype member of the heparin-binding growth factor family, is a potent mitogen for vascular endothelial cells and a variety of other cell types. FGF-1 can induce the expression of the platelet-derived growth factor-A chain (PDGF-A) gene in endothelial cells; however, the underlying transcriptional mechanisms are not known. We used serial 5' deletion and transient transfection analysis of the human PDGF-A promoter to demonstrate that a 16-bp element, located 55 to 71 bp upstream of the transcriptional start site, is required for FGF-1-inducible promoter-dependent expression. This region contains nucleotide recognition elements for the early growth response gene product, early growth response factor-1 (Egr-1), and the related zinc-finger transcription factor, Sp1. Reverse-transcription polymerase chain reaction revealed that FGF-1 induced Egr-1 mRNA expression within 30 minutes. Electrophoretic mobility shift, supershift, and Western blot analysis demonstrated that Egr-1 protein accumulated in the nuclei of endothelial cells exposed to the growth factor, whereas levels of Sp1 did not change. Egr-1 bound to the FGF-1 response element in the proximal PDGF-A promoter in a specific and time-dependent manner. These findings indicate that Egr-1 plays a key regulatory role in FGF-1-inducible endothelial PDGF-A expression and implicate this transcription factor in pathological settings in which these mitogens are both expressed.
Delbridge
G J
GJ
Centre for Thrombosis and Vascular Research, University of New South Wales, Sydney, Australia.
Khachigian
L M
LM
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D051766:Early Growth Response Protein 1; D004730:Endothelium, Vascular / Q000378:metabolism*; D016220:Fibroblast Growth Factor 1 / Q000494:pharmacology*; D006801:Humans; D017874:Immediate-Early Proteins; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis / Q000235:genetics*; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D010982:Platelet-Derived Growth Factor; D014157:Transcription Factors; C075278:platelet-derived growth factor A; D016220:Fibroblast Growth Factor 1