AMNION STRUCTURAL INTEGRITY--ONTOGENY AND REGULATION

羊膜结构完整性——个体发生和调节

• 批准号: 6301864
• 负责人: PAUL C. MACDONALD
• 金额: $ 25.1万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6301864
• 关键词: amine oxidoreductase; amnion; cadmium; chickens; collagen; crosslink; embryo /fetus cell /tissue; enzyme activity; gestational age; human tissue; mesenchyme; metallothionein; northern blottings; pregnancy; premature labor; procollagen; protein biosynthesis; smoking; tobacco abuse; western blottings

The long-range goals are to (i) define the ontogeny and regulation of interstitial collagen formation in the amnion, (ii) explore the relationship between the regulation of amnion mesenchymal cell replication and the capacity for interstitial pro-collagen synthesis/processing in these unique cells, (iii) define selected collagen-related characteristics of the "dependent" portion of the fetal membranes; and (iv) explore the cause of increased risk for pre-term premature rupture of the fetal membranes in pregnancies of women who smoke cigarettes. It has been established that the interstitial collagens of the amnion zona compacta (the principal source of fetal membrane tensile strength) are synthesized exclusively in the widely dispersed mesenchymal cells of this avascular tissue. The greatest apparent capacity for interstitial collagen synthesis in amnion occurs early in pregnancy; beginning as early as 12-14 weeks gestation, the apparent capacity for pro-collagen synthesis/processing in amnion declines abruptly, perhaps in parallel with the decrease in the density of mesenchymal cells in this tissue. Studies are described to ascertain if the decline in the apparent capacity for interstitial collagen formation in amnion is related to a decreasing density of amnion mesenchymal or, rather, is the result of a decreased in the capacity for collagen formation in the mesenchymal cells per se. The final step in collagen formation involves the cross-linking of collagen fibrils which establish tensile strength and resistance to degradation by non-specific proteases. The initial reaction in collagen cross-linking is catalyzed by lysyl oxidase (LOX), a copper (Cu/2+)-dependent enzymes. The specific activity of LOX in amnion also declines strikingly after 12-14 weeks gestation. In approximately 25% of amnions examined during the third trimester, LOX enzyme activity is very low or undetectable, much lower than would be expected from the level of immunoreactive LOS protein in the same tissue. This finding of low LOX activity/per unit LOX protein is suggestive of an amnion mesenchymal cell-specific Cu/2+ deficiency. Studies are described to evaluate the hypothesis that cadmium in amniotic fluid (AF) (from maternal blood in women who smoke) acts upon amnion epithelial cells to induce the formation of metallothioneins (MT), which are metal binding proteins. Increased levels of MT in AF/amnion epithelial cells could sequester Cu?2+ and prevent its transfer to the mesenchymal cells, the site of LOX enzyme synthesis, creating a mesenchymal cell- specific Cu/2+ deficiency in pregnancies of women who, themselves, are not Cu/2+ deficient.

长期目标是（i）定义个体发育和调节 羊膜间质胶原蛋白的形成，（ii）探索 羊膜间质细胞复制调控的关系 以及间质原胶原合成/加工的能力 这些独特的细胞，(iii) 定义了选定的胶原蛋白相关特征 胎膜的“依赖”部分； (iv) 探索 胎儿早产破裂风险增加的原因 吸烟女性怀孕期间的胎膜。它一直 确定羊膜致密带间质胶原蛋白 （胎膜拉伸强度的主要来源）合成 仅存在于这种无血管的广泛分散的间充质细胞中 组织。间质胶原合成的最大表观能力 羊膜中发生在怀孕早期；最早从 12-14 周开始 妊娠期，前胶原蛋白合成/加工的表观能力 羊膜突然下降，可能与羊膜减少同时发生。 该组织中间充质细胞的密度。研究描述为 确定间质的表观容量是否下降 羊膜中胶原蛋白的形成与羊膜密度降低有关 间充质，或者更确切地说，是能力下降的结果 间充质细胞本身形成胶原蛋白。最后一步进入 胶原蛋白的形成涉及胶原纤维的交联， 通过非特异性建立拉伸强度和抗降解性 蛋白酶。胶原交联的初始反应是由以下物质催化的 赖氨酰氧化酶 (LOX)，一种铜 (Cu/2+) 依赖性酶。具体的 12-14 周后羊膜中 LOX 的活性也显着下降 妊娠。在第三次检查中大约 25% 的羊膜中 妊娠三个月，LOX酶活性非常低或检测不到，低得多 高于免疫反应性 LOS 蛋白水平的预期 相同的组织。每单位 LOX 蛋白的 LOX 活性较低的这一发现是 提示羊膜间充质细胞特异性 Cu/2+ 缺乏。 研究旨在评估羊膜中镉的假设 液体 (AF)（来自吸烟女性的母血）作用于羊膜 上皮细胞诱导金属硫蛋白（MT）的形成， 是金属结合蛋白。 AF/羊膜上皮中 MT 水平升高 细胞可以隔离 Cu?2+ 并阻止其转移到间充质 细胞，LOX酶合成的场所，产生间充质细胞- 女性怀孕期间特定的 Cu/2+ 缺乏症，而这些女性本身并不 缺乏 Cu/2+。