Polymorphisms in the osteopontin promoter affect its transcriptional activity
Polymorphisms in the osteopontin promoter affect its transcriptional activity
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DOI：
10.1152/physiolgenomics.00138.2004
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发表时间：
2004-12-15
影响因子：
4.6
通讯作者：
Ravazzolo, R
中科院分区：
文献类型：
--
作者：
Giacopelli, F;Marciano, R;Ravazzolo, R
了解人骨桥蛋白编码基因（OPN）转录调控的分子机制可能有助于阐明几个过程，如器官损伤的纤维化演变、肿瘤发生和转移以及免疫反应，在这些过程中观察到OPN过表达。为了评估对转录有功能影响的变体，我们分析了启动子区域，并重点研究了转录起始位点上游前500 bp的三个常见变体。在一组不同的细胞系中，将携带四种最常见的单倍型（相对于- 66、- 156和- 443变体）的构建体与荧光素酶报告基因融合，结果表明，一种单倍型在所有测试细胞系中都显著降低了报告基因的表达水平。我们描述了- 66多态性改变了SP1/SP3转录因子的结合亲和力，- 156多态性包含在一个尚未表征的RUNX2结合位点，- 443多态性导致未知因子的差异结合。单倍型中不同变异组合的差异效应的发现可能有助于解释一些已经发表的文章中报道的关联研究数据。未来使用单倍型而不是单一OPN变异的关联研究将能够获得更准确的结果，可参考几种常见疾病中OPN的差异表达，其中OPN被认为是候选易感基因。
Understanding the molecular mechanisms that underlie regulation of transcription of the human osteopontin encoding gene (OPN) may help to clarify several processes, such as fibrotic evolution of organ damage, tumorigenesis and metastasis, and immune response, in which OPN overexpression is observed. With the aim to evaluate variants with functional effect on transcription, we have analyzed the promoter region and focused our investigation on three common variants present in the first 500 bp upstream of the transcription start site. Transfection of constructs carrying the four most frequent haplotypes relative to variants at - 66, - 156, and - 443 fused to the luciferase reporter gene in a panel of different cell lines showed that one haplotype conferred a significantly reduced level of reporter gene expression in all tested cell lines. We describe that the - 66 polymorphism modifies the binding affinity for the SP1/SP3 transcription factors, the - 156 polymorphism is included in a yet uncharacterized RUNX2 binding site, and the - 443 polymorphism causes differential binding of an unknown factor. The finding of differential effects of various combination of variants in haplotypes may contribute to explain data of association studies reported in several already published articles. Future association studies using haplotypes instead of single OPN variants will allow to achieve more accurate results referable to differential expression of OPN in several common diseases, in which OPN is considered a candidate susceptibility gene.