The Role of microRNA-210 in the Hypoxia Response of Cardiomyocytes

描述（由申请人提供）：缺氧是心肌缺血时心肌细胞所承受的一种关键环境应激源。MicroRNAs是一类抑制编码蛋白质的信使RNA的翻译的小RNA分子。它们在心脏发育和功能中起着至关重要的作用。然而，microrna在心肌细胞缺氧反应中的作用尚不清楚。当新生大鼠心肌细胞（nrcm）暴露于缺氧时，MicroRNA-210 （miR-210）显著上调。我们假设miR-210的上调对心肌细胞的氧化应激具有细胞保护作用。我们进一步假设miR-210的假设靶点包括缺氧诱导因子3- α (HIF-3a)， HIF-1a的负调节因子，以及铁硫簇支架同源物（IscU），一种参与铁硫蛋白合成的高度保守蛋白。铁硫蛋白是电子传递链和氧化磷酸化的重要组成部分。这些假定的靶点可能在缺氧信号传导中起着重要作用。我们将通过追求3个具体目标来检验这些假设：确定miR-210过表达是否能减少氧化诱导的细胞死亡。2. 确定miR-210敲低是否会降低缺氧情况下的生存率。3. 识别和验证miR-210在缺氧信号传导中的潜在作用，包括HIF-3a和IscU。该项目的主要目标是阐明miR-210在氧化应激下心肌细胞存活中的作用。本研究的长期目标是确定心肌缺血期间细胞保护的新治疗靶点。这个项目与公共卫生高度相关。心肌梗死是由于流向心脏的血液突然停止而导致的心脏组织死亡，是美国死亡和残疾的首要原因之一。然而，细胞死亡不会立即发生，因此，在血流恢复之前保护细胞免于死亡可能是一种有用的策略。在这个项目中，我们探索一种新的分子，microRNA-210，在保护心脏细胞免于死亡中可能发挥的作用以及这种作用的可能机制。

DESCRIPTION (provided by applicant): Hypoxia is a critical environmental stressor to which cardiomybcytesare subjected during myocardial ischemia. MicroRNAs are a class of small RNA molecules which inhibit translation of protein-encoding messenger RNAs. They play critical roles in cardiac development and function. Yet the role of microRNAsin the hypoxia response of cardiomyocytes remains unknown. MicroRNA-210 (miR-210) is profoundly upregulated when neonatal rat cardiomyocytes (NRCMs) are exposed to hypoxia. We hypothesize that this upregulation of miR-210 is cytoprotective against oxidative stress in cardiomyocytes. We further hypothesize that putative targets of miR-210 include hypoxia-inducible factor 3-alpha (HIF-3a), a negative regulator of HIF-1a, and iron-sulfur cluster scaffold homolog (IscU), a very highly conserved protein involved in iron-sulfur protein synthesis. Iron-sulfur proteins constitute an integral part of the electron transport chain and oxidative phosphorylation. These putative targets may play fundamental roles in hypoxia signaling. We will test these hypotheses by pursuing 3 specific aims: 1. To determine whether miR-210 overexpression reduces oxidant-induced cell death. 2. To determine whether miR-210 knockdown reduces survival in the presence of hypoxia. 3. To identify and validate putative targets of miR-210 with potential roles in hypoxia signaling, including HIF-3a and IscU. The major goal of this project is to elucidate the role of miR-210 in cardiomyocyte survival during oxidative stress. The long-term objective of this research is to identify novel therapeutic targets for cytoprotection during myocardial ischemia. This project is highly relevant to public health. Myocardial infarction, the death of heart tissue because of a sudden cessation of blood flow to the heart, is one of the top causes of death and disability in the United States. Cell death does not happen immediately, however, and protecting cells from dying until blood flow is restored may therefore be a useful strategy. In this project, we explore the role that a new molecule, microRNA-210, may play in protecting heart cells from death as well as possible mechanisms for this effect.