MicroRNAs, cardiac development and function

描述(申请人提供)：microRNAs(MiRNAs)是最近发现的一类小的调节性RNA分子，在大多数生物体中发现，包括人类。MiRNAs由基因组编码并加工成~22个核苷酸产物，主要通过降解靶信使RNA(MRNAs)和/或抑制编码蛋白质的mRNAs的翻译而发挥重要的调节作用。有趣的是，许多miRNAs是以组织特异性的方式表达的，这表明它们在调节组织特异性基因表达方面具有潜在的作用。然而，由于在哺乳动物中发现了400多个miRNAs，大多数miRNAs的分子机制和体内功能仍不清楚。在我们的初步研究中，我们发现miR-1、miR-133、miR-206和miR-208是肌肉特异表达的(因此被称为肌肉miRNAs)。MiR-1和miR-133在成肌细胞中的异位表达或下调调控其增殖和分化过程，表明miRNAs对动物的发育和功能具有重要作用。我们研究的长期目标是了解控制心肌发育和功能的分子机制。MiRNAs的发现为研究miRNAs如何参与“经典”基因表达途径开辟了一个全新的领域。我们的中心假设是miRNAs是控制哺乳动物心脏发育和功能的分子电路的组成部分。这项建议的总体目标是以心肌作为我们的模型系统，探索miRNA功能的分子机制。特别是，我们将研究心脏特异性miR-208的体外和体内功能，并确定其参与心肌分化和发育的调控靶点。此外，我们将使用DICER条件基因敲除小鼠来评估miRNAs在心脏发育中的全球作用。目的1.研究miR-208在体外和体内对心脏发育和心脏基因表达的影响。目的#2.利用DICER条件性基因敲除小鼠，确定miRNA介导的心肌调节的全球作用。目的#3.确定并实验测试心脏中miRNAs的调控靶点。确定心脏中miRNAs调控的mRNA靶点将是理解miRNA功能分子机制的关键。我们将使用计算预测和实验验证相结合的方法来研究心脏中被miRNAs抑制的调控靶点。我们的研究将为控制哺乳动物心脏发育和心脏基因表达的miRNAs背后的分子机制提供重要的见解。这些研究中揭示的分子策略可能适用于与病理生理相关的心肌事件，如人类先天性心脏病(CHD)、心力衰竭和心肌肥厚。

DESCRIPTION (provided by applicant): MicroRNAs (miRNAs) are a recently identified class of small regulatory RNA molecules found in most organisms, including human. miRNAs are encoded by the genomes and processed into ~ 22-nucleotide products which are thought to play important regulatory role, mainly through degrading target messenger RNAs (mRNAs) and/or inhibiting translation of protein-coding mRNAs. Interestingly, many miRNAs are expressed in a tissue-specific manner, suggesting their potential roles in regulating tissue-specific gene expression. However, given more than 400 miRNAs identified in mammals, the molecular mechanisms and the in vivo functions of most miRNAs remain unknown. In our preliminary studies, we found that miR-1, miR- 133, miR-206 and miR-208 are muscle-specifically expressed (and therefore referred to as "muscle miRNAs"). Ectopic expression or knockdown of miR-1 and miR-133 in myoblasts modulates their proliferation and differentiation processes, indicating that miRNAs are importance for animal development and function. The long-term goal of our research is to understand the molecular mechanisms that control development and function of cardiac muscle. The discovery of miRNAs opened a completely new field to investigate how miRNAs may participate in "classical" gene expression pathways. Our central hypothesis is that miRNAs are components of the molecular circuitry that controls mammalian cardiac development and function. The overall goal of this proposal is to explore the molecular mechanisms of miRNA function, using cardiac muscle as our model system. In particular, we will study the in vitro and in vivo function of cardiac- specific miR-208 and identify its regulatory targets which are involved in cardiac muscle differentiation and development. In addition, we will assess the global role of miRNAs in heart development, using Dicer conditional knockout mice. The specific aims are: Aim #1. To study the in vitro and in vivo role of miR- 208 in heart development and cardiac gene expression. Aim #2. To define the global role of miRNA- mediated regulation in cardiac muscle using Dicer conditional knock-out mice. Aim #3. To identify and experimentally test the regulatory targets of miRNAs in the heart. Identification of the regulatory mRNA targets of miRNAs in the heart will be the key to the understanding of the molecular mechanisms of miRNA function. We will use a combination of computational prediction and experimental confirmation to study the regulatory targets repressed by miRNAs in the heart. Our studies will provide important insights into the molecular mechanisms behind miRNAs that control mammalian heart development and cardiac gene expression. The molecular strategies revealed in these studies may apply to pathophysiologically- related cardiac muscle events such as human congenital heart defects (CHD), cardiac failure and cardiac hypertrophy.