A new player in placental dysfunction: mir210

描述(申请人提供)：医学和科学中一个令人兴奋的新领域是microRNAs的发现。MicroRNAs(MiRNAs)是高度保守的单链非编码小RNA分子，在转录后基因调控中起着关键作用。在许多不同的生物学领域，新出现的证据已经确定miRNAs是疾病状态中的关键角色。MicroRNA210(miR-210)是一种独特的低氧诱导的miRNA，可在多种细胞中诱导表达。MiR-210的表达是否增强或保护了对低氧的病理反应似乎是一个细胞、组织和疾病特有的事件。MiR-210在滋养细胞和胎盘功能中的作用仍有待发现，这也是本研究的重点。对该R21的新假设是，miR-210在妊娠早期的滋养细胞功能中起关键作用，miR-210的异常表达导致胎盘功能障碍。我们假设miR-210是不良妊娠结局(APO)的重要介质，不良妊娠结局源于胎盘功能障碍，如先兆子痫、宫内发育受限和胎儿死亡。在正常妊娠中，胎盘是在相对低氧的条件下发育的。我们认为，在一些妇女中，这段缺氧期更严重和/或更长时间；反过来，这种缺氧导致滋养层细胞侵袭和功能异常，导致胎盘功能障碍，最终发展为APOS。我们的初步数据支持我们的假设，即miR-210是胎盘功能障碍的关键调节因子。利用原代绒毛外滋养层细胞，我们发现：1)在低氧环境下，绒毛外滋养层细胞miR-210的表达显著增加；2)miR-210在绒毛外滋养层细胞中的过度表达导致滋养层细胞的侵袭显著减弱；以及3)内源性miR-210的阻断增加了滋养层的侵袭。这些数据支持miR-210在调节滋养细胞侵袭中的重要作用，并提示miR-210的表达增加促进了一种病理状态。此外，使用现有临床试验中的生物样品，我们已经证明，与没有这些不良后果的妇女相比，在诊断为APO时，母亲血液中miR-210的含量增加。重要的是，我们还证明，在此类APOS临床发病前几个月，母亲血液中miR-210水平也会升高。这些数据表明，miR-210可能不仅是APOS的潜在生物标志物，而且可能在机制上参与了胎盘功能障碍的发展。为了进一步探讨miR-210在滋养细胞功能中的作用，我们建立了一种局部宫内缺氧的小鼠模型，以探索更长时间的宫内缺氧如何改变胎盘功能。在这个模型中，只有在胎盘中有胎儿丢失和与持续低氧途径相一致的分子表型。虽然其他用于研究低氧诱导的滋养层功能障碍的啮齿动物模型利用全身低氧，但我们的模型仅在胎儿-胎盘单位的水平上创造了低氧环境。利用体外和体内模型，我们将探索miR-210是否是胎盘功能障碍的重要和新的介体。

DESCRIPTION (provided by applicant): An exciting new field in medicine and science is the discovery of microRNAs. MicroRNAs (miRNAs) are small highly conserved single-stranded non-coding RNA molecules that play a critical role in post transcriptional gene regulation. Emerging evidence, in many different biological arenas, has identified miRNAs as critical players in diseases states. MicroRNA 210 (miR-210) has emerged as a unique hypoxia-induced miRNA that is induced in many cell types. Whether miR-210 expression serves to augment or protect the pathologic response to hypoxia appears to be a cell, tissue and disease specific event. The role of miR-210 in trophoblast and placental function remains to be discovered and is the focus of this proposal. The novel hypothesis for this R21 is that miR-210 plays a critical role in trophoblast function early in pregnancy and aberrant expression of miR-210 results in placental dysfunction. We hypothesize that miR-210 is an important mediator of adverse pregnancy outcomes (APO)-which originate from placental dysfunction-such as preeclampsia, intrauterine growth restriction and fetal demise. In normal pregnancy, the placenta develops in relatively hypoxic conditions. We propose that, in some women, this period of hypoxia is more severe and/or prolonged; in turn, this hypoxia leads to aberrations in trophoblast invasion and function resulting in placental dysfunction with the eventual development of APOs. Our preliminary data support our hypothesis that miR-210 is a critical mediator of placental dysfunction. Using primary extravillous trophoblasts (EVTs), we have demonstrated the following: 1) miR-210 is significantly increased in EVTs exposed to hypoxia; 2) over-expression of miR-210 in EVTs results in significantly impaired trophoblast invasion; and 3) blocking of endogenous miR-210 increases trophoblast invasion. These data support an essential role of miR-210 in regulation of trophoblast invasion and suggest that increased expression of miR-210 promotes a pathological state. Furthermore, using biospecimens from existing clinical trials, we have demonstrated that miR-210 is increased in maternal blood at the time of diagnosis of an APO compared to women without these adverse outcomes. Importantly, we have also demonstrated that miR-210 levels are also increased in maternal blood months prior to the clinical onset of such APOs. These data suggest that miR-210 may not just a potential biomarker of APOs but also may be mechanistically involved in the development of the placental dysfunction. To further explore the role of miR- 210 in trophoblast function, we have created a mouse model of local intrauterine hypoxia to explore how a more prolonged period of intrauterine hypoxia alters placental function. In this model, there is fetal loss and a molecular phenotype consistent with persistent hypoxic pathways only in the placenta. While other rodent models used to study hypoxia-induced trophoblast dysfunction utilize systemic hypoxia, our model creates a hypoxic environment only at the level of the feto-placental unit. Using both in vitro (EVTs) and in vivo models, we will explore if miR-210 is an important and novel mediator of placental dysfunction.