| Autor: |
Czuwara-Ladykowska, Joanna, Shirasaki, Fumiaki, Jackers, Pascale, Watson, Dennis K., Trojanowska, Maria |
| Zdroj: |
Journal of Biological Chemistry; June 2001, Vol. 276 Issue: 24 p20839-20848, 10p |
| Abstrakt: |
Fibrosis is characterized by the excessive deposition of extracellular matrix (ECM), especially collagen. Because Ets factors are implicated in physiological and pathological ECM remodeling, the aim of this study was to investigate the role of Ets factors in collagen production. We demonstrate that the expression of collagenous proteins and collagen α2(I) (COL1A2) mRNA was inhibited following stable transfection of Fli-1 in dermal fibroblasts. Subsequent analysis of the COL1A2promoter identified a critical Ets binding site that mediates Fli-1 inhibition. In contrast, Ets-1 stimulates COL1A2promoter activity. In vitrobinding assays demonstrate that both Fli-1 and Ets-1 form DNA-protein complexes with sequences present in COL1A2 promoter. Furthermore, Fli-1 binding to the COL1A2is enhanced via Sp1-dependent interaction. Studies using Fli-1 dominant interference and DNA binding mutants indicate that Fli-1 inhibition is mediated by both direct (DNA binding) and indirect (via protein-protein interaction) mechanisms and that Sp1 is an important mediator of the Fli-1 function. Furthermore, experiments using the Gal4 system in the context of different cell types as well as experiments with theCOL1A2promoter in different cell lines demonstrate that the direction and magnitude of the effect of Fli-1 is promoter- and cell context-specific. We propose that Fli-1 inhibitsCOL1A2promoter activity by competition with Ets-1. In addition, we postulate that another factor (co-repressor) may be required for maximal inhibition after recruitment to the Fli-1-Sp1 complex. We conclude that the ratio of Fli-1 to Ets-1 and the presence of co-regulatory proteins ultimately control ECM production in fibroblasts. |
| Databáze: |
Supplemental Index |
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