The role of microRNA in cardiac cell death

microRNA在心肌细胞死亡中的作用

基本信息

批准号：
7948531
负责人：
Maha Abdellatif
金额：
$ 39万
依托单位：
UNIV OF MED/DENT OF NJ-NJ MEDICAL SCHOOL
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-15 至 2014-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7948531
关键词：
3&apos Untranslated Regions AKT inhibition Apoptosis Apoptosis Inhibitor Binding Cancerous Cardiac Cardiac Myocytes Cell Death Cells Chromosomes, Human, Pair 10 Chronic Coronary artery Dilatation - action Down-Regulation Feedback Fibrosis Gene Targeting Genes Heart Homologous Gene Hypoxia Infarction Injury Ischemia Knowledge MicroRNAs Mus Muscle Cells Myocardial Ischemia Organogenesis Pathogenesis Pathway interactions Phenotype Phosphoric Monoester Hydrolases Process Proteins Proto-Oncogene Proteins c-akt RNA-Binding Proteins Regulation Relative (related person)Role Signal Pathway Signal Transduction Therapeutic Transgenic Mice Transgenic Organisms Translations Tumor Necrosis Factor Ligand Superfamily Member 6 Up-Regulation Wild Type Mouse artery occlusion cell growth in vivo mouse model preconditioning public health relevance tensin therapeutic target

项目摘要

DESCRIPTION (provided by applicant): MicroRNA are major posttranscriptional regulatory molecules that mainly suppress protein translation through binding their 3'UTR. MicroRNA-21 (miR-21) is highly upregulated during hypertrophic or cancerous cell growth. In contrast, we found that it declines upon exposure of cardiac myocytes to prolonged hypoxia. Thus, our main objective is to investigate the signaling pathway that regulates miR-21, its targets, and their role in myocyte survival during hypoxia or ischemia. Our preliminary results show that miR-21 not only regulates phosphatase and tensin homologue deleted on chromosome 10 (PTEN), but also directly targets Fas Ligand (FasL). During hypoxia, downregulation of miR-21 is necessary and sufficient for enhancing the expression of both proteins. Consequently, supplementing the cells with exogenous miR-21 during hypoxia is an effective inhibitor of apoptosis. We also observed that activated AKT suppresses the expression of PTEN and FasL in myocytes and induces upregulation of miR-21. To explore the function of miR-21 in the heart in vivo, we generated a cardiac-specific miR-21 transgenic mouse model. These mice have no overt cardiac phenotype, however, following chronic coronary artery occlusion there was complete suppression of PTEN and FasL expression, smaller infarct size, and less fibrosis and chamber dilatation, in the miR-21 transgenic versus the wild type mice. Accordingly, cardiac functions were better preserved. Thus, our hypotheses are: 1) AKT is activated by brief hypoxic episodes [hypoxia preconditioning (HPC)] and induces upregulation of miR-21 in cardiac myocytes or the heart. Conversely, prolonged hypoxia is associated with inhibition of AKT, which results in downregulation of miR-21. 2) AKT phosphorylates the RNA-binding protein CUGBP1, which binds the loop region of primary miR-21 and enhances its processing, thus, increasing mature miR-21 levels. 3) MiR-21 directly targets and regulates translation of PTEN and FasL. Thus, downregulation of miR-21 during hypoxia is required and sufficient for enhancing their translation. 4) Modulation of PTEN levels by the AKT- miR-21 pathway inversely regulates AKT activity and, thus, creates a feedback loop that perpetuates signaling through this pathway. 5) FasL is strictly localized to the interface between myocytes and relays apoptosis signals between cells. Thus, suppression of FasL by miR-21 limits the spread of apoptosis. 6) Supplementing cells with exogenous miR-21 suppresses the expression of these targets and reduces myocyte apoptosis during hypoxia or ischemia. Thus, the aims are to: 1) Delineate the upstream pathways and mechanisms involved in the regulation of miR-21 and its functional signficance. 2) Examine the mechanisms of function of miR-21 and its target genes, FasL and PTEN, in cardiac myocytes. 3) Study the function of miR-21 and its regulation in vivo. PUBLIC HEALTH RELEVANCE: MicroRNA are posttranscriptional regulators that have proven critical for organogenesis and pathogenesis. But until now we have very little knowledge of the their targets and mechanism of function. A single miRNA has the capacity to target multiple functionally- related genes, which is why we think they would be more effective therapeutic targets relative to a single gene approach. For example, miR-21 upregulation would not only target and inhibit PTEN, but would also inhibit FasL, which equally contributes to the demise of myocytes during ischemic injury. Our proposal involves investigating the full range of the antiapoptotic function of miR-21 in the heart. This would be the first step to exploit it for a therapeutic cardioprotective effect during ischemic heart disease.

描述（由申请人提供）：microRNA是主要的后调节分子，主要通过结合其3'UTR抑制蛋白质翻译。在肥厚或癌细胞生长过程中，microRNA-21（miR-21）高度上调。相比之下，我们发现它会在心肌细胞暴露于长时间缺氧时下降。因此，我们的主要目标是研究调节miR-21，其靶标的信号传导途径及其在低氧或缺血期间其在肌细胞生存中的作用。我们的初步结果表明，miR-21不仅调节在10（PTEN）上删除的磷酸酶和Tensin同源物，而且还直接靶向FAS配体（FASL）。在缺氧期间，MiR-21的下调是必要的，足以增强两种蛋白质的表达。因此，在缺氧期间补充外源性miR-21的细胞是凋亡的有效抑制剂。我们还观察到激活的AKT抑制了肌细胞中PTEN和FASL的表达，并诱导miR-21的上调。为了探索miR-21在体内心脏中的功能，我们产生了心脏特异性miR-21转基因小鼠模型。这些小鼠没有明显的心脏表型，但是，在慢性冠状动脉闭塞后，在miR-21转基因中，PTEN和FASL表达完全抑制了PTEN和FASL表达，较小的梗塞大小以及纤维化和室内扩张较少，而野生型小鼠则完全抑制。因此，心脏功能得到了更好的保存。因此，我们的假设是：1）AKT通过简短的低氧发作[缺氧预处理（HPC）]激活，并在心肌细胞或心脏中诱导miR-21的上调。相反，长时间的缺氧与抑制AKT有关，这导致miR-21的下调。 2）AKT磷酸化RNA结合蛋白CUGBP1，该蛋白CUGBP1结合了初级miR-21的环区并增强其加工，从而增加了成熟的miR-21水平。 3）miR-21直接靶向并调节PTEN和FASL的翻译。因此，需要在缺氧期间miR-21的下调，足以增强其翻译。 4）Akt-miR-21途径对PTEN水平的调节反向调节AKT活动，因此创建了一个反馈回路，该反馈使通过该途径发出信号。 5）FASL严格定位于细胞之间的肌细胞和继电器凋亡信号之间的界面。因此，通过miR-21对FASL的抑制限制了凋亡的扩散。 6）补充外源性miR-21的细胞抑制这些靶标的表达，并减少缺氧或缺血期间的心肌细胞凋亡。因此，目的是：1）描述MIR-21调节及其功能标志性的上游途径和机制。 2）检查心肌细胞中miR-21及其靶基因FASL和PTEN功能的功能机理。 3）研究miR-21及其在体内调节的功能。公共卫生相关性：microRNA是已证明对器官发生和发病机理至关重要的转录后调节剂。但是直到现在，我们对它们的目标和功能机理的了解很少。单个miRNA具有靶向多个功能相关的基因的能力，这就是为什么我们认为它们相对于单个基因方法将是更有效的治疗靶标。例如，miR-21上调不仅会靶向和抑制PTEN，而且还会抑制FASL，这同样有助于缺血性损伤期间肌细胞的灭亡。我们的建议涉及研究miR-21在心脏中的全部抗凋亡功能。这将是在缺血性心脏病期间利用它来利用它的治疗性心脏保护作用的第一步。