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

描述(申请人提供)：缺氧是心肌细胞在心肌缺血期间受到的一种关键环境应激源。MicroRNAs是一类抑制蛋白质编码信使RNAs翻译的小RNA分子。它们在心脏发育和功能中起着关键作用。然而，microRNAs在心肌细胞缺氧反应中的作用尚不清楚。新生大鼠心肌细胞缺氧时，microRNA-210(miR-210)表达显著上调。我们假设miR-210的这种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的可能靶点包括缺氧诱导因子3-α(HIF-3a)，它是HIF-1a的负调控因子，以及铁-硫簇支架同源物(IscU)，它是一种参与铁-硫蛋白合成的高度保守的蛋白质。铁硫蛋白是电子传递链和氧化磷酸化的重要组成部分。这些可能的靶点可能在低氧信号转导中发挥重要作用。我们将通过追求三个特定的目标来验证这些假说：1.确定miR-210的过表达是否减少了氧化剂诱导的细胞死亡。2.确定miR-210基因敲除是否降低了低氧条件下的存活率。3.确定并验证miR-210在低氧信号转导中的潜在作用靶点，包括HIF-3a和IscU。本项目的主要目的是阐明miR-210在氧化应激期间心肌细胞存活中的作用。这项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。这个项目与公众健康高度相关。心肌梗死是由于流向心脏的血液突然停止而导致心脏组织死亡，是美国死亡和残疾的主要原因之一。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不死亡可能是一个有用的策略。在这个项目中，我们探索了一种新的分子，microRNA-210，可能在保护心脏细胞免于死亡方面发挥作用，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.