Mechanisms of newborn pulmonary hypertension caused by chronic intrauterine hypoxia

项目总结 慢性宫内缺氧不仅在中国的1.4亿人中很常见 世界生活在高海拔地区，但也有许多妊娠并发症，如先兆子痫， 吸烟和胎盘功能不全。胎儿对慢性缺氧结果的适应 在许多不利的发育结果中，包括新生儿的肺动脉高压。 BKCa通道对新生儿肺血管系统的松弛起关键作用 出生。我们已建立的慢性缺氧胎羊模型的最新结果 妊娠表明BKCa通道功能障碍是肺动脉高压的一个原因。这个 这项提案的工作将研究细胞缺氧和BKCa之间的机制联系 渠道功能障碍。其他人最近的研究表明，“主要的次氧核糖核酸”miR210，一个 被HIF-1上调的Micro-RNA通过抑制 铁-硫簇组装蛋白ISCU的翻译。由此导致的铁硫缺乏 集群会导致线粒体功能障碍。我们假设慢性宫内缺氧 通过激活HIF-1？→miR210→ISCU轴而导致肺动脉高压， 导致线粒体衍生的活性氧增加，从而导致BKCa通道 功能障碍。 我们提出了三个具体目标。每个特定的目标都被设计成在体外和在 体内方法，以便更好地确定体外结果与肺组织的相关性 完好的动物的功能。目标1将侧重于确定BKCA的机制 通道功能障碍，以及确定BKCa通道功能丧失是否单独 足以导致完整羔羊的肺动脉高压。目标2将重点放在 缺氧诱导的miR210对ISCU活性、铁-硫簇水平和 线粒体功能和活性氧的产生。在完好无损的羔羊中，我们将 确定在没有缺氧的情况下，该通路的激活是否会导致肺 高血压，以及在低氧情况下抑制这一途径是否能阻止BKCa 经络功能与肺动脉高压。目标3将调查增加的 慢性低氧反应中的活性氧水平在BKCA中起致病作用 经络功能与肺动脉高压。使用体外和体内方法，我们将 确定全球抗氧化剂维生素C或线粒体特异性抗氧化剂MitoQ 可预防慢性宫内缺氧引起的肺动脉高压。

PROJECT SUMMARY Chronic intrauterine hypoxia is common amongst not only the 140 million people in the world living at high altitudes but also in many complications of pregnancy such as preeclampsia, cigarette smoking, and placental insufficiency. Adaptation of the fetus to chronic hypoxia results in many adverse developmental outcomes, including pulmonary hypertension of the newborn. The BKCa channel is critical to the relaxation of the pulmonary vasculature of the newborn at birth. Recent results from our well-established fetal lamb model of chronic hypoxia during pregnancy points to BKCa channel dysfunction as a causal factor in pulmonary hypertension. The work in this proposal will investigate the mechanistic link between cellular hypoxia and BKCa channel dysfunction. Recent work by others indicates that the ‘master hypoxamir’ miR210, a micro-RNA that is upregulated by HIF-1?, orchestrates pulmonary hypertension by suppressing translation of the iron-sulfur cluster assembly protein ISCU. The resulting lack of iron-sulfur clusters results in mitochondrial dysfunction. We hypothesize that chronic intrauterine hypoxia leads to pulmonary hypertension by activation of the HIF-1? → miR210 → ISCU axis, resulting in increased mitochondrial-derived reactive oxygen species that lead to BKCa channel dysfunction. We propose three specific aims. Each specific aim is designed to integrate in vitro and in vivo approaches in order to better ascertain the relevance of the in vitro results to pulmonary function of the intact animal. Aim 1 will focus on determining the mechanism underlying BKCa channel dysfunction, and on establishing whether loss of BKCa channel function alone is adequate to result in pulmonary hypertension in intact lambs. Aim 2 will focus on the effects of hypoxia-induced increases in miR210 on ISCU activity, iron-sulfur cluster levels, and mitochondrial function and reactive oxygen species production. In intact lambs, we will establish whether activation of this pathway in the absence of hypoxia results in pulmonary hypertension, and whether suppression of this pathway in the presence of hypoxia prevents BKCa channel function and pulmonary hypertension. Aim 3 will investigate whether the increased reactive oxygen species levels in response to chronic hypoxia play a causative role in BKCa channel function and pulmonary hypertension. Using both in vitro and in vivo methods, we will determine whether the global antioxidant Vitamin C or mitochondria-specific antioxidant MitoQ will prevent pulmonary hypertension caused by chronic intrauterine hypoxia.