The functional role of microRNAs in the normal mammary gland

MicroRNAs(MiRNAs)是一种小的(19-25个核苷酸)未翻译的RNA，起着调节 信使RNA表达。在大多数情况下，miRNAs与3‘端的互补区结合 靶mRNA的非翻译区(UTRs)，并导致信使核糖核酸降解或阻止翻译。 已经发现miRNAs在特定的发育阶段以细胞特有的方式表达 在疾病状态下有不同的表达。出生后小鼠乳腺中的miRNA图谱 揭示了不同关键发育阶段(处女期、妊娠期、哺乳期)miRNA表达的变化 和内陷)，强烈表明miRNA在乳腺发育中发挥调节作用。 然而，miRNAs在乳腺中的调节机制及其特定的功能 在发展的关键阶段发挥的作用仍未得到探索。因此，这个项目的总体目标是 确定小鼠体内分泌激活过程中miRNAs的激素调节和功能作用 乳腺。由于怀孕和哺乳期之间发生了戏剧性的新陈代谢变化， 乳腺是研究miRNA对新陈代谢基因影响的独特模型。我们的特定 AIMS将检验miRNAs代表调节分泌激活的重要机制的假设 通过影响编码葡萄糖转运蛋白、脂肪合成酶和乳蛋白的基因的翻译。 我们已经观察到，在怀孕中期和哺乳期之间减少的特定miRNAs，靶基因 参与脂肪酸合成的编码酶、葡萄糖摄取的转运体和翻译启动 因子，elF4e。这些miRNAs的减少缓解了抑制，增加了目标基因的翻译。 此外，由于在怀孕期间，孕酮及其受体抑制终末分化和 分泌激活直到分娩发生，我们将确定配体激活的PR是否起作用 通过miRNAs介导这种抑制。我们将探索孕激素受体是否调节 MiRNAs的表达，反过来，miRNAs是否介导孕酮的下调 感受器。在3D之前，我们将通过慢病毒转导到原代微血管内皮细胞来操纵miRNAs 体内培养，用腺病毒导管内注射到小鼠乳腺内，并经乳腺 使用Cre重组酶特异性缺失感兴趣的miRNA。这些研究将直接提供 MiRNAs在调节乳腺新陈代谢中作用的证据。 相关性(请参阅说明)： 在乳腺中，哺乳需要一种被称为“分泌性”的深刻而快速的发育开关。 在我们的研究中，我们研究了microRNAs(小的非编码RNA，即 同时控制许多编码RNA的翻译)是戏剧性新陈代谢的主要调节器 在怀孕和哺乳期之间发生的变化。这个项目的目标是定义荷尔蒙 乳腺分泌物激活过程中microRNAs的调节和功能作用。

MicroRNAs (miRNAs) are small (19-25 nucleotides) untranslated RNAs that serve as regulators of messenger RNA expression. For the most part, miRNAs bind to complementary regions in the 3' untranslated regions (UTRs) of target mRNA, and either cause mRNA degradation or prevent translation. MiRNAs have been found to be expressed in cell-specific manner, at specific developmental stages, as well as differentially expressed in disease states. MiRNA profiling in the post-natal mouse mammary gland has revealed alterations in miRNA expression at different key developmental stages (virgin, pregnancy, lactation and involution), strongly suggesting that miRNA play a regulatory role in mammary gland development. However, mechanisms by which miRNAs are regulated in the mammary gland and their specific functional roles at critical stages of development remain unexplored. Therefore, the overall goal of this project is to determine the hormonal regulation and functional roles of miRNAs during secretory activation in the mammary gland. Because of the dramatic metabolic changes occurring between pregnancy and lactation, the mammary gland is a unique model to study the Impact of miRNA on metabolism genes. Our specific aims will test the hypothesis that miRNAs represent an important mechanism regulating secretory activation by influencing translation of genes encoding glucose transporters, lipid synthetic enzymes and milk proteins. We have observed that specific miRNAs that decrease between mid-pregnancy and lactation, target genes encoding enzymes involved in fatty acid synthesis, transporters for glucose uptake and a translation initiation factor, elF4e. A decline in these miRNAs relieves repression and increases translation of target genes. Additionally, since during pregnancy, progesterone and its receptors inhibit terminal differentiation and secretory activation until parturition has occurred, we will determine whether ligand activated PR acts through miRNAs to mediate this inhibition. We will explore whether progesterone receptors regulate expression of miRNAs and, conversely, whether miRNAs mediate down regulation of progesterone receptors. We will manipulate miRNAs in vitro via lentiviral transduction into primary MECs prior to 3D culture, in vivo using adenovirus injected intraductally into the mammary glands of mice, and by mammary gland-specific deletion of miRNA of interest using Cre recombinase. These studies will provide direct evidence for the role of miRNAs in modulating metabolism in the mammary gland. RELEVANCE (See instructions): In the mammary gland, lactation requires a profound and rapid developmental switch termed "secretory activation." In our study we investigate the hypothesis that microRNAs (small non-coding RNAs that simultaneously control translation of many coding RNAs) are master regulators of the dramatic metabolic changes that occur between pregnancy and lactation. The goal of this project is to define the hormonal regulation and functional roles of microRNAs during secretorv activation in the mammary aland.