Comparative functional study of the lysyl oxidase promoter in fibroblasts, Ras-transformed fibroblasts, myofibroblasts and smooth muscle 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.
Reynaud
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C
Institut de Biologie et Chimie des Protéines, Centre National de la Recherche Scientifique, Lyon, France.
Gleyzal
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Jourdan-Le Saux
C
C
Sommer
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P
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D004742:Enhancer Elements, Genetic; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter / Q000235:genetics; D011905:Genes, ras; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics* / Q000378:metabolism; D051381:Rats
D008156:Luciferases; D008249:Protein-Lysine 6-Oxidase