The functional role of microRNAs in the normal mammary gland

微小RNA（miRNAs）是小的（19-25个核苷酸）非翻译RNA，其作为转录因子的调节因子。 信使RNA表达。在大多数情况下，miRNAs结合到3'端的互补区域， 靶mRNA的非翻译区（UTR），并导致mRNA降解或阻止翻译。 miRNAs在特定的发育阶段以细胞特异性的方式表达， 在疾病状态下的差异表达。出生后小鼠乳腺中的miRNA谱 揭示了在不同的关键发育阶段（处女、妊娠、哺乳）miRNA表达的变化 和退化），强烈表明miRNA在乳腺发育中起调节作用。 然而，miRNAs在乳腺中的调节机制及其特定的功能性调控机制尚不清楚。 在发展的关键阶段的作用仍未得到探讨。因此，本项目的总体目标是 确定激素调节和功能作用的miRNAs在分泌激活过程中， 乳腺由于在怀孕和哺乳之间发生的剧烈的代谢变化， 乳腺是研究miRNA对代谢基因影响的独特模型。我们的具体 目的是验证miRNAs是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、脂质合成酶和乳蛋白的基因的翻译。 我们已经观察到，在妊娠中期和哺乳期减少的特定miRNA，靶基因 编码参与脂肪酸合成、葡萄糖摄取转运蛋白和翻译起始的酶 因子，elF 4 e。这些miRNAs的减少解除了抑制并增加了靶基因的翻译。 此外，由于在妊娠期间，孕酮及其受体抑制终末分化， 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介导这种抑制作用。我们将探讨孕酮受体是否调节 miRNAs的表达，反之，miRNAs是否介导孕酮的下调， 受体。我们将在体外通过慢病毒转导将miRNAs导入原发性MEC，然后进行3D转染。 培养，在体内使用腺病毒导管内注射到小鼠的乳腺中，和通过乳腺 使用Cre重组酶的目的miRNA的腺特异性缺失。这些研究将提供直接 miRNA在调节乳腺代谢中的作用的证据。 相关性（参见说明）： 在乳腺中，泌乳需要一个深刻而快速的发育转换，称为“分泌型”。 activation.“在我们的研究中，我们调查了一个假设，即microRNA（小的非编码RNA， 同时控制许多编码RNA的翻译）是戏剧性的代谢的主要调节因子。 怀孕和哺乳之间发生的变化。这个项目的目标是定义荷尔蒙 在乳腺腺分泌激活过程中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.