Wang Hongyan, Ogawa Masaki, Wood Jennifer R, Bartolomei Marisa S, Sammel Mary D, Kusanovic Juan Pedro, Walsh Scott W, Romero Roberto, Strauss Jerome F
State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University School of Life Science, Shanghai 200433, China.
Hum Mol Genet. 2008 Apr 15;17(8):1087-96. doi: 10.1093/hmg/ddm381. Epub 2008 Jan 4.
Degradation of fibrillar collagens is believed to be involved in the rupture of the fetal membranes during normal parturition and when the membranes rupture prematurely. Matrix metalloproteinase 1 (MMP1) is a key enzyme involved in extracellular matrix turnover, and genetic variation in the MMP1 promoter is associated with the risk of preterm premature rupture of membranes (PPROM). We determined whether epigenetic factors contribute to the control of MMP1 expression in the human amnion. Inhibition of DNA methylation with 5-aza-2'-deoxycytidine in amnion fibroblasts resulted in significantly increased MMP1 gene transcription, and an associated significant increase in MMP1 production. These effects were correlated with reduced DNA methylation at a particular site (-1538) in the MMP1 promoter. DNA methylation at this site in amnion was reduced in a larger percentage of fetal membranes that ruptured prematurely. A new T > C single nucleotide polymorphism (SNP) [AF007878.1 (MMP1):g.3447T>C] in the MMP1 promoter was also identified. The minor C allele was always methylated in vivo, and when methylated, resulted in increased affinity for a nuclear protein in amnion fibroblasts. The minor C allele had reduced promoter activity as assessed by plasmid transfection studies and chromatin immunoprecipitation assays using amnion fibroblasts heterozygous for the T > C SNP. In a case-control study, the minor C allele was found to be protective against PPROM, consistent with its reduced promoter function. We conclude that in addition to genetic variation, DNA methylation plays a role in controlling MMP1 expression and risk of an adverse obstetrical outcome.
人们认为，在正常分娩以及胎膜过早破裂时，纤维状胶原蛋白的降解与胎膜破裂有关。基质金属蛋白酶1（MMP1）是参与细胞外基质周转的关键酶，MMP1启动子的基因变异与早产胎膜早破（PPROM）的风险相关。我们确定了表观遗传因素是否有助于控制人羊膜中MMP1的表达。用5-氮杂-2'-脱氧胞苷抑制羊膜成纤维细胞中的DNA甲基化，导致MMP1基因转录显著增加，同时MMP1产生也显著增加。这些效应与MMP1启动子中特定位点（-1538）的DNA甲基化减少相关。在更大比例的过早破裂的胎膜中，羊膜中该位点的DNA甲基化减少。还在MMP1启动子中鉴定出一个新的T > C单核苷酸多态性（SNP）[AF007878.1（MMP1）：g.3447T>C]。次要的C等位基因在体内总是甲基化的，甲基化时会导致羊膜成纤维细胞中对一种核蛋白的亲和力增加。通过质粒转染研究以及使用T > C SNP杂合的羊膜成纤维细胞进行的染色质免疫沉淀分析评估，次要的C等位基因具有降低的启动子活性。在一项病例对照研究中，发现次要的C等位基因对PPROM具有保护作用，与其降低的启动子功能一致。我们得出结论，除了基因变异外，DNA甲基化在控制MMP1表达和不良产科结局风险方面发挥作用。
