Structural insertion/deletion variation in IRF5 is associated with a risk haplotype and defines the precise IRF5 isoforms expressed in systemic lupus erythematosus
Structural insertion/deletion variation in IRF5 is associated with a risk haplotype and defines the precise IRF5 isoforms expressed in systemic lupus erythematosus
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DOI：
10.1002/art.22497
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发表时间：
2007-04-01
影响因子：
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通讯作者：
Alarcon-Riquelme, Marta E.
中科院分区：
文献类型：
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作者：
Kozyrev, Sergey V.;Lewen, Susanna;Alarcon-Riquelme, Marta E.
Objective.目的探讨系统性红斑狼疮（SLE）患者是否存在IRF 5的特异性亚型转录，这些患者在外显子113供体剪接位点的单核苷酸多态性（SNP）rs 2004640处具有风险基因型。外周血单核细胞来自阿根廷、西班牙和德国的SLE患者和健康对照以及来自西班牙和丹麦的三个家庭。使用报告基因测定来研究SNP号rs 2004640的作用。使用定量聚合酶链反应分析IRF 5表达与功能性SNP基因型的关系。对IRF 5基因进行测序和基因分型。不同基因型个体的互补DNA测序显示，从所有5 '-非翻译区（5'-UTR）转录的4种基本异构体，表明没有基于rs 2004640基因型的优先异构体转录。翻译效率的分析表明，外显子1A是最有效的启动蛋白质合成。我们确定了一种新的多态性插入/缺失，定义了IRF 5亚型的表达模式。插入由外显子6中的4个重复组成，影响蛋白质相互作用结构域。插入在风险单倍型中分离，其具有多聚（A）位点SNP号rs 10954213的高表达等位基因和5 '-UTR SNP号rs 2004640的外显子1B供体剪接等位基因。poly（A）多态性与干扰素-α刺激的细胞中IRF 5的水平相关。与SLE相关性最强的SNP是SNP编号rs 2070197（P = 5.2 x 10（-11）），它是风险单倍型的代表，但似乎没有功能。在这项研究中，没有一个功能变异与SLE密切相关，除了外显子1B供体剪接位点，其功能的重要性似乎很小。我们的研究结果表明，可能有其他功能的多态性，尚未确定，在IRF 5。我们没有观察到功能SNP之间上位相互作用的证据。
Objective. To determine whether specific isoforms of IRF5 are transcribed in patients with systemic lupus erythematosus (SLE) who have risk genotypes in the exon 113 donor splice site at single-nucleotide polymorphism (SNP) no. rs2004640.Methods. Peripheral blood mononuclear cells were obtained from SLE patients and healthy controls from Argentina, Spain, and Germany and from trio families from Spain and Denmark. A reporter assay was used to investigate the role of SNP no. rs2004640. IRF5 expression in relation to the genotypes of functional SNPs was analyzed using quantitative polymerase chain reaction. Sequencing and genotyping of the IRF5 gene was performed.Results. Sequencing of complementary DNA from individuals with different genotypes showed 4 basic isoforms transcribed from all 5'-untranslated regions (5'-UTRs), suggesting no preferential isoform transcription based on rs2004640 genotypes. Analysis of translation efficiency showed that exon 1A was the most efficient in initiating protein synthesis. We identified a novel polymorphic insertion/deletion that defines the pattern of expression of isoforms of IRF5. The insertion consists of 4 repeats in exon 6 affecting the protein interaction domain. The insertion segregates in the risk haplotype with the high expression allele of a poly(A) site SNP no. rs10954213 and the exon 1B donor splice allele of the 5'-UTR SNP no. rs2004640. The poly(A) polymorphism correlated with levels of IRF5 in cells stimulated with interferon-alpha. The SNP most strongly associated with SLE was SNP no. rs2070197 (P = 5.2 x 10(-11)), which is a proxy of the risk haplotype, but does not appear to be functional.Conclusion. None of the functional variants investigated in this study is strongly associated with SLE, with the exception of the exon 1B donor splice site, and its functional importance appears to be small. Our results suggest that there may be other functional polymorphisms, yet to be identified, in IRF5. We did not observe evidence of epistatic interaction between the functional SNPs.