| Author/Editor | Chen, Shu-Jen; Ning, Hongyan; Ishida, Wataru; Sodin-Šemrl, Snežna; Takagawa, Shinsuke; Mori, Yasuji; Varga, John | |
| Title | The early-immediate gene EGR-1 is induced by transforming growth factor-beta and mediates stimulation of collagen gene expression | |
| Type | članek | |
| Source | J Biol Chem | |
| Vol. and No. | Letnik 281, št. 30 | |
| Publication year | 2006 | |
| Volume | str. 21183-97 | |
| Language | eng | |
| Abstract | Transforming growth factor-beta (TGF-I3) stimulates collagen synthesis and accumulation, and aberrant TGF-13 signaling is implicated in pathological organ fibrosis. Regulation of Type I procollagen gene (COL1A2) transcription by TGF-beta involves the canonical Smad signaling pathway as well as additional protein and lipid kinases, coactivators and DNA-binding transcription factors that constitute alternate non-Smad pathways. Using Affymetrix microarrays to detect cellular genes whose expression is regulated by Smad3, we identified early growth response factor-1 (Egr-1) as a novel Smad3-inducible gene. Previous studies implicated Egr-1 in cell growth, differentiation and survival. We found that TGF-beta induced rapid and transient accumulation of Egr-1 protein and mRNA in human skin fibroblasts. In transient transfection assays, TGF-beta stimulated the activity of the Egr-1 gene promoter, as well as that of a minimal Egr-1responsive reporter construct. Furthermore, TGF-beta enhanced endogenous Egr-1 interaction with a consensus Egr-1 binding site element, and with GC-rich DNA sequences of the human COL1A2 promoter in vitro and in vivo. Forced expression of Egr-1 by itself caused doseIependent up-regulation of COL1A2 promoter activity, and further enhanced the stimulation nduced by TGF-beta. In contrast, the TGF-beta Response was abrogated when the Egr-1 Binding sites of the COL1A2 promoter were nutated or deleted. Furthermore, Egr-1leficient embryonic mouse fibroblasts showed attenuated TGF-beta responses despite intact Smad activation, and forced expression of ectopic Egr-1 in these cells could restore COL1A2 stimulation in a dose-dependent manner. Taken together, these findings identify Egr-1 as a novel intracellular TGF-beta target that is necessary for maximal stimulation of collagen gene expression in fibroblasts. (Abstract truncated at 2000 characters) | |
| Descriptors | TRANSFORMING GROWTH FACTOR BETA COLLAGEN GENE EXPRESSION REGULATION FIBROBLASTS SIGNAL TRANSDUCTION BASE SEQUENCE MOLECULAR SEQUENCE DATA OLIGONUCLEOTIDE PROBES MICE |