Reynaud C, Gleyzal C, Jourdan-Le Saux C, Sommer P
Institut de Biologie et Chimie des Protéines, Centre National de la Recherche Scientifique, Lyon, France.
Cell Mol Biol (Noisy-le-grand). 1999 Dec;45(8):1237-47.
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.
赖氨酰氧化酶（LOX）是一种参与胶原蛋白和弹性蛋白交联以及肿瘤抑制的酶，我们比较了其在细胞外基质产生细胞和致瘤性c-Ha-ras-NIH-3T3成纤维细胞（RS485）中的启动子活性。完整的2kb小鼠LOX启动子在3T6-5肌成纤维细胞样细胞（MFLC）和血管平滑肌细胞（SMC）中非常活跃，而在ras转化的成纤维细胞中受到抑制。正向顺式作用元件位于MFLC和SMC的转录起始位点周围，但在RS485成纤维细胞及其未转化的对应细胞中均未发现。主要的正向顺式作用片段位于-808至-585位，在所有细胞中均有活性，在MFLC和SMC中活性最强，而位于-758至-726位的一个片段允许与所有细胞的核因子形成一种主要的DNA-蛋白质复合物。主要的抑制区域位于-1362至-1176位，在所有成纤维细胞中均有活性，但在SMC中无活性，无论是在上游位置还是在增强子/沉默子位置。该区域有两个片段，因其与COL1A1和COL1A2启动子序列相似而被称为LOcoll和LOcol2，它们参与与所有细胞的核因子形成一个大型多因子DNA复合物，不过对SMC来说作用稍弱。另一个区域在-898至-886位携带一个假定的干扰素反应元件（IRF），对每种细胞类型都有负向作用。总之，LOX启动子受正向和负向顺式作用区域之间的相互作用控制，这些区域在不同细胞中具有不同的活性。-758至-726区域及其假定的C/EBP位点以及转录起始区域可能在激活有纤维生成能力的MFLC和SMC中的LOX启动子方面起主要作用。而具有假定B-Myb结合位点的LOcol1/2片段以及携带IRF的区域在转化细胞中对LOX启动子起负向作用。
