Recurrent pregnancy loss -associated promoter polymorphisms affect ANXA5 ge ne expression via G -quadruplex propensity

最近的研究结果强调了膜联蛋白A5基因（ANXA 5）启动子内的多态性与各种产科并发症的病因学有关的可能性。然而，其潜在机制尚不清楚。在本研究中，我们在G-四链体形成的背景下检测了ANXA 5基因启动子的转录活性。启动子多态性的M2单倍型赋予了这些疾病的高发病风险，显示出较低的活性和较少的ANXA 5 mRNA表达。该基因启动子区有一个潜在的G-四链体结构的基序，M2等位基因具有比主要等位基因更低的潜力。荧光素酶报告基因分析测定的启动子活性与圆二色性测定的体外G-四链体倾向相关。用G-四链体配体处理抑制了这种启动子活性。综上所述，我们的数据表明，M2等位基因煽动G-四链体介导的转录调控，从而下调胎盘抗凝因子膜联蛋白A5的水平，导致产科疾病，我们的数据支持的发展模式，基因组变异影响基因表达水平通过DNA二级结构，导致疾病的易感性。

Recent findings have highlighted the possibility that polymorphismswithin the annexin A5 gene (ANXA5) promoter contribute to the etiology of various obstetriccomplications. However, the underlying mechanisms are unknown. In our present study, thetranscriptional activity of the ANXA5gene promoter was examined in the context of G-quadruplexformation. The M2 haplotype of the promoter polymorphisms that confers a high risk of onset forthese disorders shows lower activity and less expression of ANXA5 mRNA. This gene promoterregion has a motif that potentially forms a G-quadruplex structure, and the M2 allele possesses lesspotential than the major allele. The promoter activity determined by luciferase reporter analysiscorrelated with the in vitro G-quadruplex propensity estimated by circular dichroism. Treatmentwith a G-quadruplex ligand inhibited this promoter activity. Taken together, our data indicate thatthe M2 allele instigates G-quadruplex-mediated transcriptional regulation and consequentlydownregulates the placental anticoagulation factor annexin A5 levels, leading to obstetric disorders.Our data lend support to the developing paradigm that genomic variation affects gene expressionlevels via DNA secondary structures leading to the disease susceptibility.