MicroRNA in Liver Development and Disease

描述（由申请人提供）： 基因表达的调控是生物发育和体内平衡的核心。在 近年来，人们发现了一种意想不到的基因调控形式，其中小RNA 被称为microRNA（miRNAs）的分子通过RNA抑制靶基因的表达， 干扰在人类基因组中有超过500种miRNAs，它们可以共同 控制着20-30%的基因事实上，关于miRNA在肝脏中的功能， 发展和疾病。 为了解决这个问题，我们已经定量了小鼠肝脏发育过程中所有miRNA的表达。我们已经确定了一组miRNAs的表达显着上升期间的肝胆分化和形态发生，我们已经开始本地化其表达的原位杂交。这种方法已经产生了胚胎肝脏中发育调节的miRNA的第一个例子。一种miRNA（miR-30 a）在胆管板和胆管中表达。我们对miR-30 a的初步研究首次证明了胆道发育需要miRNA。将在肝分化的细胞培养模型中评估miR-30 a和其他肝miRNA的功能（Aim 1A）。该系统还将用于鉴定肝脏miRNA的分子靶标（Aim 1A）。小鼠遗传模型将用于测试miR-30 a和选定的miRNA在体内的发育功能（Aim 1B）。 许多疾病是由正常发育途径的畸变引起的。胆道闭锁是小儿肝移植的主要指征，与发育异常有关。尽管作出了相当大的努力，但其原因尚不清楚。尽管我们发现miR-30 a在胆道闭锁的增殖胆管中高度表达，但miRNA在胆道闭锁中的作用从未被探索过。我们将利用作为胆道闭锁研究联盟临床研究的一部分收集的标本来表征胆道闭锁组织和对照中所有miRNA的表达（目的2A）。这将通过使用胆道闭锁小鼠模型的平行研究进行补充。然后通过在小鼠模型中抑制miRNA来测试miRNA的致病作用（Aim 2B）。这些研究有可能揭示胆道闭锁的发病机制，并可能导致新的治疗方法。 这项研究是重要的，因为它将揭示新的调节途径，在正常的肝脏发育和胆道闭锁。它直接解决了NIH肝脏研究行动计划关于肝脏发育和确定胆道闭锁原因的目标。

DESCRIPTION (provided by applicant): The control of gene expression is at the core of biological development and homeostasis. In recent years, an unexpected form of gene regulation has been discovered in which small RNA molecules known as microRNAs (miRNAs) repress the expression of target genes through RNA interference. There are over 500 miRNAs in the human genome, and collectively they may regulate 20-30% of all genes. Virtually nothing is known regarding the function of miRNA in liver development and disease. To address this, we have quantified the expression of all miRNAs during mouse liver development. We have identified a set of miRNAs whose expression rises significantly during the period of hepatobiliary differentiation and morphogenesis, and we have begun to localize their expression by in situ hybridization. This approach has yielded the first examples of developmentally regulated miRNAs in the embryonic liver. One miRNA (miR-30a) is expressed in the ductal plate and bile ducts. Our preliminary work on miR-30a has resulted in the first evidence of a requirement for a miRNA in biliary development. The function of miR-30a and other hepatic miRNAs will be assessed in a cell culture model of liver differentiation (Aim 1A). This system will be also be used to identify the molecular targets of hepatic miRNAs (Aim 1A). The mouse genetic model will be used to test the developmental function of miR-30a and selected miRNAs in vivo (Aim 1B). Many diseases are caused by aberrations in normal developmental pathways. Biliary atresia, the leading indication for pediatric liver transplantation, is associated with developmental anomalies. Despite considerable efforts, its cause is unknown. The role of miRNA in biliary atresia has never been explored, although we have found that miR-30a is highly expressed in the proliferating bile ducts characteristic of biliary atresia. We will utilize specimens collected as part of the Biliary Atresia Resarch Consortium clinical study to characterize the expression of all miRNA in biliary atresia tissue and controls (Aim 2A). This will be complemented by a parallel study using a mouse model of biliary atresia. The pathogenic role of miRNA will then be tested by inhibition of miRNAs in the mouse model (Aim 2B). These studies have the potential to shed light on biliary atresia pathogenesis and may result in new treatments. The research proposed is significant because it will reveal novel regulatory pathways in normal liver development and in biliary atresia. It directly addresses goals of the NIH Action Plan for Liver Research regarding liver development and identification of the cause of biliary atresia.