0 avis
Comparative functional study of the lysyl oxidase promoter in fibroblasts, Ras-transformed fibroblasts, myofibroblasts and smooth muscle cells.
Archive ouverte
Edité par CCSD ; CMB Association -
International audience. The promoter activity of lysyl oxidase (LOX), the enzyme involved in collagen and elastin cross-linking and in tumor suppression, was compared in extracellular matrix producing cells and in tumorigenic c-Ha-ras-NIH-3T3 fibroblasts (RS485). The full 2 kb murine LOX promoter was very active in 3T6-5 myofibroblast-like cells (MFLC) and vascular smooth muscle cells (SMC) and was inhibited in ras-transformed fibroblasts. Positive cis-acting elements were located around sites of transcription initiation in MFLC and SMC, but neither in RS485 fibroblasts nor in their non-transformed counterparts. The main positive cis-acting segment, at positions -808 to -585, was active in all cells, with the strongest activity in MFLC and SMC, and one segment, at positions -758 to -726, allowed the formation of one master DNA-protein complex with nuclear factors from all cells. The main inhibiting region, at positions -1,362 to -1,176, was active in all fibroblasts, but not in SMC, in an upstream position or in an enhancer/silencer position. This region carries two segments, called LOcoll and LOcol2 for their similarity to COL1A1 and COL1A2 promoter sequences, that were involved in the formation of a large multifactorial DNA complex with nuclear factors from all cells, though slightly for SMC. Another region, carrying a putative interferon response element (IRF) at positions -898 to -886, acted negatively on each type of cells. In conclusion, the LOX promoter is controlled by cross-talk between positive and negative cis-acting regions that are differentially active in various cells. The -758 to -726 region, with its putative C/EBP site, and the transcription initiation region are likely to play a master role in activating the LOX promoter in fibrocompetent MFLC and SMC. While the LOcol1/2 segment, with putative B-Myb binding sites, and the IRF carrying region, work negatively on the LOX promoter in transformed cells.The promoter activity of lysyl oxidase (LOX), the enzyme involved in collagen and elastin cross-linking and in tumor suppression, was compared in extracellular matrix producing cells and in tumorigenic c-Ha-ras-NIH-3T3 fibroblasts (RS485). The full 2 kb murine LOX promoter was very active in 3T6-5 myofibroblast-like cells (MFLC) and vascular smooth muscle cells (SMC) and was inhibited in ras-transformed fibroblasts. Positive cis-acting elements were located around sites of transcription initiation in MFLC and SMC, but neither in RS485 fibroblasts nor in their non-transformed counterparts. The main positive cis-acting segment, at positions -808 to -585, was active in all cells, with the strongest activity in MFLC and SMC, and one segment, at positions -758 to -726, allowed the formation of one master DNA-protein complex with nuclear factors from all cells. The main inhibiting region, at positions -1,362 to -1,176, was active in all fibroblasts, but not in SMC, in an upstream position or in an enhancer/silencer position. This region carries two segments, called LOcoll and LOcol2 for their similarity to COL1A1 and COL1A2 promoter sequences, that were involved in the formation of a large multifactorial DNA complex with nuclear factors from all cells, though slightly for SMC. Another region, carrying a putative interferon response element (IRF) at positions -898 to -886, acted negatively on each type of cells. In conclusion, the LOX promoter is controlled by cross-talk between positive and negative cis-acting regions that are differentially active in various cells. The -758 to -726 region, with its putative C/EBP site, and the transcription initiation region are likely to play a master role in activating the LOX promoter in fibrocompetent MFLC and SMC. While the LOcol1/2 segment, with putative B-Myb binding sites, and the IRF carrying region, work negatively on the LOX promoter in transformed cells.
Consulter en ligne
Suggestions
Du même auteur
