Mechanisms of Fetal Membrane Rupture

描述(申请人提供)：早产胎膜早破(PPROM)是产妇发病率和早产的主要原因。在当前支持期间进行的研究表明，编码基质金属蛋白酶(MMPs)的基因多态性导致非计划性胎膜破裂的风险。我们现在建议1)确定参与胶原合成和翻译后修饰的编码蛋白的基因变异，包括编码调节胶原合成的伴侣蛋白的SERPINH1基因和催化胶原交联的赖氨酰氧化酶(LOX)基因家族是否增加了PPROM的风险。要检验的假设是：1)SERPINH1基因的656 T等位基因是导致非裔美国人早产的种族选择因素；2)656 T SNP附近的12个碱基缺失与656 T等位基因对胎盘早产的不利影响相反；3)12个碱基缺失增加了SERPINH1启动子的活性，缓解了656 T等位基因的影响；4)携带656 T等位基因的羊膜成纤维细胞胶原合成减少，但在存在12个碱基缺失的情况下，656 T等位基因不影响羊膜成纤维细胞的胶原合成；5)656 T等位基因携带者羊膜原纤维胶原含量降低，但当存在12个碱基缺失时不会减少；6)656 T等位基因的剂量与羊膜成纤维细胞胶原合成、羊膜胶原含量以及PPROM的风险相关；7)LOX基因家族存在功能多态，导致基因表达或酶活性改变，并与PPROM的风险相关；8)这些变异影响羊膜胶原的交联。根据初步数据，注意力将集中在LOXL1基因上。一项基于双胞胎的早产遗传学研究将被纳入，作为确定遗传性和基因发现的新方法。2)确定表观遗传因素是否影响PPROM候选基因的表达。需要检验的假设是：1)基质金属蛋白酶和胶原合成基因启动子中CpG岛的甲基化变化调节基因表达；2)某些甲基化标记导致等位基因特异性转录；3)羊膜型PPROM候选基因的甲基化状态因个体而异；4)这些影响转录的基因的甲基化模式与PPROM的风险相关；5)表观遗传标记修改遗传变异的影响。这一假设将以MMP1启动子930T/C SNP为样本进行验证。拟议的研究代表了临床和实验室研究的综合，这些研究将包括与正在研究的遗传变异相关的分子和生化分析。这些研究将揭示导致PPROM的遗传和表观遗传因素，包括早产的种族/民族差异，允许识别PPROM的风险妇女，并确定预测PPROM的遗传标记。拟议中的研究将确定参与胶原合成的蛋白质编码基因中的变异或表观遗传因素是否会增加PPROM的风险。

DESCRIPTION (provided by applicant): Preterm premature rupture of the fetal membranes (PPROM) is a major cause of maternal morbidity and premature birth. Studies conducted during the current period of support revealed that polymorphisms in genes encoding matrix metalloproteinases (MMPs) contribute to risk of unscheduled membrane rupture. We now propose to 1) determine whether variants in genes encoding proteins involved in collagen synthesis and posttranslational modification, including the SERPINH1 gene, which encodes a chaperone that regulates collagen synthesis, and the lysyl oxidase (LOX) gene family which catalyze collagen cross- linking, confer risk of PPROM. The hypotheses to be tested are that: 1) the 656 T allele of the SERPINH1 gene is an ethnic-selective factor contributing to preterm birth in African-Americans; 2) a 12 bp deletion adjacent to the 656 T SNP opposes the adverse effect of the 656 T allele on PPROM; 3) the 12 bp deletion increases SERPINH1 promoter activity mitigating the effect of the 656 T allele; 4) collagen synthesis is reduced in amnion fibroblasts carrying the 656 T allele, but not the 656 T allele in the presence of the 12 bp deletion; 5) the fibrillar collagen content of the amnion is reduced in carriers of the 656 T allele, but not when the 12 bp deletion is present; 6) the 656 T allele dose is correlated with amnion fibroblast collagen synthesis and amnion collagen content, as well as risk of PPROM; 7) that functional polymorphisms exist in the LOX gene family that result in altered gene expression or enzymatic activity and are associated with risk of PPROM; and 8) that these variants affect amnion collagen cross-linking. Based on preliminary data, attention will be focused on the LOXL1 gene. A twin-based study of the genetics of preterm birth will be incorporated as a new approach to establish heritability and gene finding. 2) determine if epigenetic factors contribute to expression of PPROM candidate genes. The hypotheses to be tested are: 1) that variation in methylation of CpG islands in the promoters of MMP and collagen synthesis genes regulate gene expression; 2) that certain metyhylation marks result in allele-specific transcription; 3) that methylation status of amnion PPROM candidate genes varies among individuals; 4) that methylation patterns of these genes that influence transcription are associated with risk of PPROM; 5) that epigenetic marks modify the impact of genetic variation. This hypothesis will be tested using the MMP1 promoter 930 T/C SNP as an exemplar. The proposed studies represent a synthesis of clinical and laboratory research that will encompass molecular and biochemical analyses that relate to the genetic variants under investigation. These studies will disclose genetic and epigenetic factors that contribute to PPROM including racial/ethnic disparity in preterm birth, allow the identification of women at risk of PPROM, and identify genetic markers predicting PPROM.Preterm premature rupture of the fetal membranes (PPROM) is a major cause of maternal morbidity and premature birth. The proposed studies will determine whether variants or epigenetic factors in genes encoding proteins involved in collagen synthesis confer risk of PPROM.